From 00b04ac41d748c0d3d1f732c06330f832fc61186 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Wed, 20 Dec 2023 22:40:37 +0100
Subject: [PATCH 01/18] add Swoole backend

---
 .github/workflows/ci.yml      |  2 +-
 src/Backends/Swoole.php       | 92 +++++++++++++++++++++++++++++++++++
 tests/Backends/SwooleTest.php | 81 ++++++++++++++++++++++++++++++
 3 files changed, 174 insertions(+), 1 deletion(-)
 create mode 100644 src/Backends/Swoole.php
 create mode 100644 tests/Backends/SwooleTest.php

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b992d288c..84e25068b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,7 +20,7 @@ jobs:
         with:
           php-version: ${{ matrix.php-versions }}
           tools: composer, pecl
-          extensions: svm, mbstring, gd, fileinfo
+          extensions: svm, mbstring, gd, fileinfo, swoole
           ini-values: memory_limit=-1
 
       - name: Validate composer.json
diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
new file mode 100644
index 000000000..3f11a4893
--- /dev/null
+++ b/src/Backends/Swoole.php
@@ -0,0 +1,92 @@
+<?php
+
+namespace Rubix\ML\Backends;
+
+use Rubix\ML\Backends\Tasks\Task;
+
+use function Swoole\Coroutine\batch;
+
+/**
+ * Swoole
+ *
+ * Works both with Swoole and OpenSwoole.
+ *
+ * @category    Machine Learning
+ * @package     Rubix/ML
+ */
+class Swoole implements Backend
+{
+    /**
+     * The queue of tasks to be processed in parallel.
+     *
+     * @var list<array{Task,callable(mixed,mixed):void|null,mixed|null}>
+     */
+    protected array $queue = [
+        //
+    ];
+
+    protected float $timeout;
+
+    public function __construct(float $timeout = -1)
+    {
+        $this->timeout = $timeout;
+    }
+
+    /**
+     * Queue up a deferred task for backend processing.
+     *
+     * @internal
+     *
+     * @param \Rubix\ML\Backends\Tasks\Task $task
+     * @param callable(mixed,mixed):void $after
+     * @param mixed $context
+     */
+    public function enqueue(Task $task, ?callable $after = null, $context = null) : void
+    {
+        $this->queue[] = function () use ($task, $after, $context) {
+            $result = $task();
+
+            if ($after) {
+                $after($result, $context);
+            }
+
+            return $result;
+        };
+    }
+
+    /**
+     * Process the queue and return the results.
+     *
+     * @internal
+     *
+     * @return mixed[]
+     */
+    public function process() : array
+    {
+        $results = batch($this->queue, $this->timeout);
+
+        $this->queue = [];
+
+        return $results;
+    }
+
+    /**
+     * Flush the queue
+     */
+    public function flush() : void
+    {
+        $this->queue = [];
+    }
+
+    /**
+     * Return the string representation of the object.
+     *
+     * @internal
+     *
+     * @return string
+     */
+    public function __toString() : string
+    {
+        return 'Swoole';
+    }
+}
diff --git a/tests/Backends/SwooleTest.php b/tests/Backends/SwooleTest.php
new file mode 100644
index 000000000..2736b41d2
--- /dev/null
+++ b/tests/Backends/SwooleTest.php
@@ -0,0 +1,81 @@
+<?php
+
+namespace Rubix\ML\Tests\Backends;
+
+use Rubix\ML\Backends\Swoole;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Tasks\Task;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @group Backends
+ * @group Swoole
+ * @covers \Rubix\ML\Backends\Swoole
+ */
+class SwooleTest extends TestCase
+{
+    /**
+     * @var \Rubix\ML\Backends\Swoole
+     */
+    protected $backend;
+
+    /**
+     * @param int $i
+     * @return int
+     */
+    public static function foo(int $i) : int
+    {
+        return $i * 2;
+    }
+
+    /**
+     * @before
+     */
+    protected function setUp() : void
+    {
+        if (!extension_loaded('openswoole') && !extension_loaded('swoole')) {
+            $this->markTestSkipped(
+                'Swoole/OpenSwoole extension is not available.'
+            );
+
+            return;
+        }
+
+        $this->backend = new Swoole();
+    }
+
+    /**
+     * @test
+     */
+    public function build() : void
+    {
+        $this->assertInstanceOf(Swoole::class, $this->backend);
+        $this->assertInstanceOf(Backend::class, $this->backend);
+    }
+
+    /**
+     * @test
+     */
+    public function enqueueProcess() : void
+    {
+        for ($i = 0; $i < 10; ++$i) {
+            $this->backend->enqueue(new Task([self::class, 'foo'], [$i]));
+        }
+
+        $results = $this->backend->process();
+
+        $this->assertCount(10, $results);
+        $this->assertEquals([
+            0,
+            2,
+            4,
+            6,
+            8,
+            10,
+            12,
+            14,
+            16,
+            18,
+        ], $results);
+    }
+}

From 946cab891e4b44d387ad34d245df3ca2cc790ac8 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Wed, 20 Dec 2023 22:53:49 +0100
Subject: [PATCH 02/18] phpstan: ignore swoole

---
 phpstan.neon                  | 1 +
 src/Backends/Swoole.php       | 2 +-
 tests/Backends/SwooleTest.php | 2 --
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/phpstan.neon b/phpstan.neon
index 90d5425c3..4d1ae5782 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -6,3 +6,4 @@ parameters:
         - 'benchmarks'
     excludePaths:
         - src/Backends/Amp.php
+        - src/Backends/Swoole.php
diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 3f11a4893..01cdf65ec 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -19,7 +19,7 @@ class Swoole implements Backend
     /**
      * The queue of tasks to be processed in parallel.
      *
-     * @var list<array{Task,callable(mixed,mixed):void|null,mixed|null}>
+     * @var list<callable>
      */
     protected array $queue = [
         //
diff --git a/tests/Backends/SwooleTest.php b/tests/Backends/SwooleTest.php
index 2736b41d2..6a1bbc594 100644
--- a/tests/Backends/SwooleTest.php
+++ b/tests/Backends/SwooleTest.php
@@ -37,8 +37,6 @@ protected function setUp() : void
             $this->markTestSkipped(
                 'Swoole/OpenSwoole extension is not available.'
             );
-
-            return;
         }
 
         $this->backend = new Swoole();

From 606363369efc0ea71bd6a66e320c909acc0b0156 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Sat, 6 Jan 2024 09:09:51 +0100
Subject: [PATCH 03/18] feat: swoole process scheduler

---
 .../{Swoole.php => Swoole/Coroutine.php}      |   7 +-
 src/Backends/Swoole/Process.php               | 127 ++++++++++++++++++
 .../CoroutineTest.php}                        |  21 ++-
 tests/SwooleProcessBackend.php                |  24 ++++
 4 files changed, 170 insertions(+), 9 deletions(-)
 rename src/Backends/{Swoole.php => Swoole/Coroutine.php} (92%)
 create mode 100644 src/Backends/Swoole/Process.php
 rename tests/Backends/{SwooleTest.php => Swoole/CoroutineTest.php} (74%)
 create mode 100644 tests/SwooleProcessBackend.php

diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole/Coroutine.php
similarity index 92%
rename from src/Backends/Swoole.php
rename to src/Backends/Swoole/Coroutine.php
index 01cdf65ec..bf9341124 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole/Coroutine.php
@@ -1,7 +1,8 @@
 <?php
 
-namespace Rubix\ML\Backends;
+namespace Rubix\ML\Backends\Swoole;
 
+use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Tasks\Task;
 
 use function Swoole\Coroutine\batch;
@@ -14,7 +15,7 @@
  * @category    Machine Learning
  * @package     Rubix/ML
  */
-class Swoole implements Backend
+class Coroutine implements Backend
 {
     /**
      * The queue of tasks to be processed in parallel.
@@ -87,6 +88,6 @@ public function flush() : void
      */
     public function __toString() : string
     {
-        return 'Swoole';
+        return 'Swoole\\Coroutine';
     }
 }
diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
new file mode 100644
index 000000000..b464ac9f8
--- /dev/null
+++ b/src/Backends/Swoole/Process.php
@@ -0,0 +1,127 @@
+<?php
+
+namespace Rubix\ML\Backends\Swoole;
+
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Tasks\Task;
+use RuntimeException;
+use Swoole\Process\Pool;
+use Swoole\Table;
+
+/**
+ * Swoole
+ *
+ * Works both with Swoole and OpenSwoole.
+ *
+ * @category    Machine Learning
+ * @package     Rubix/ML
+ */
+class Process implements Backend
+{
+    /**
+     * The queue of tasks to be processed in parallel.
+     */
+    protected array $queue = [];
+
+    private $cpus;
+
+    public function __construct()
+    {
+        $this->cpus = swoole_cpu_num();
+    }
+
+    /**
+     * Queue up a deferred task for backend processing.
+     *
+     * @internal
+     *
+     * @param \Rubix\ML\Backends\Tasks\Task $task
+     * @param callable(mixed,mixed):void $after
+     * @param mixed $context
+     */
+    public function enqueue(Task $task, ?callable $after = null, $context = null) : void
+    {
+        $this->queue[] = function () use ($task, $after, $context) {
+            $result = $task();
+
+            if ($after) {
+                $after($result, $context);
+            }
+
+            return $result;
+        };
+    }
+
+    /**
+     * Process the queue and return the results.
+     *
+     * @internal
+     *
+     * @return mixed[]
+     */
+    public function process() : array
+    {
+        $resultsTable = new Table(count($this->queue) * 2);
+        $resultsTable->column('result', Table::TYPE_FLOAT);
+        $resultsTable->create();
+
+        $workersTable = new Table($this->cpus);
+        $workersTable->column('working', Table::TYPE_INT);
+        $workersTable->create();
+
+        $pool = new Pool($this->cpus);
+        $pool->on('WorkerStart', function (Pool $pool, $workerId) use ($resultsTable, $workersTable) {
+            try {
+                if (!$workersTable->exist($workerId)) {
+                    $workersTable->set($workerId, [
+                        'working' => 1,
+                    ]);
+
+                    for ($i = $workerId; $i < count($this->queue); $i += $this->cpus) {
+                        if (!$resultsTable->exist($i)) {
+                            $resultsTable->set($i, [
+                                'result' => $this->queue[$i](),
+                            ]);
+                        }
+                    }
+                }
+            } finally {
+                $pool->shutdown();
+            }
+        });
+        $pool->start();
+
+        $results = [];
+
+        for ($i = 0; $i < count($this->queue); $i += 1) {
+            $results[] = $resultsTable->get($i, 'result');
+        }
+
+        return $results;
+    }
+
+    /**
+     * Flush the queue
+     */
+    public function flush() : void
+    {
+        $this->queue = [];
+    }
+
+    /**
+     * Return the string representation of the object.
+     *
+     * @internal
+     *
+     * @return string
+     */
+    public function __toString() : string
+    {
+        return 'Swoole\\Process';
+    }
+
+    private static function nextPowerOf2($number)
+    {
+        return pow(2, ceil(log($number,2)));
+    }
+}
diff --git a/tests/Backends/SwooleTest.php b/tests/Backends/Swoole/CoroutineTest.php
similarity index 74%
rename from tests/Backends/SwooleTest.php
rename to tests/Backends/Swoole/CoroutineTest.php
index 6a1bbc594..f8ab50dd7 100644
--- a/tests/Backends/SwooleTest.php
+++ b/tests/Backends/Swoole/CoroutineTest.php
@@ -1,21 +1,22 @@
 <?php
 
-namespace Rubix\ML\Tests\Backends;
+namespace Rubix\ML\Tests\Backends\Swoole;
 
-use Rubix\ML\Backends\Swoole;
+use Rubix\ML\Backends\Swoole\Coroutine as SwooleCoroutineBackend;
 use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Tasks\Task;
 use PHPUnit\Framework\TestCase;
+use Swoole\Event;
 
 /**
  * @group Backends
  * @group Swoole
  * @covers \Rubix\ML\Backends\Swoole
  */
-class SwooleTest extends TestCase
+class CoroutineTest extends TestCase
 {
     /**
-     * @var \Rubix\ML\Backends\Swoole
+     * @var \Rubix\ML\Backends\Swoole\Coroutine
      */
     protected $backend;
 
@@ -39,7 +40,15 @@ protected function setUp() : void
             );
         }
 
-        $this->backend = new Swoole();
+        $this->backend = new SwooleCoroutineBackend();
+    }
+
+    /**
+     * @after
+     */
+    protected function tearDown(): void
+    {
+        Event::wait();
     }
 
     /**
@@ -47,7 +56,7 @@ protected function setUp() : void
      */
     public function build() : void
     {
-        $this->assertInstanceOf(Swoole::class, $this->backend);
+        $this->assertInstanceOf(SwooleCoroutineBackend::class, $this->backend);
         $this->assertInstanceOf(Backend::class, $this->backend);
     }
 
diff --git a/tests/SwooleProcessBackend.php b/tests/SwooleProcessBackend.php
new file mode 100644
index 000000000..f2d1653d8
--- /dev/null
+++ b/tests/SwooleProcessBackend.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Rubix\ML\Tests\Backends\Swoole;
+
+require_once __DIR__.'/../vendor/autoload.php';
+
+use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Tasks\Task;
+use PHPUnit\Framework\TestCase;
+use Swoole\Event;
+
+$backend = new SwooleProcessBackend();
+
+for ($i = 0; $i < 1000; ++$i) {
+    $backend->enqueue(new Task(function ($input) {
+        return $input * 2;
+    }, [$i]));
+}
+
+$results = $backend->process();
+
+var_dump(count($results));
+var_dump($results);

From d812f8f9afbb7413047798334ee34b21e03230d3 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 16:14:13 +0100
Subject: [PATCH 04/18] fix(swoole): redo tasks when hash collision happens

---
 composer.json                               |  3 +-
 phpunit.xml                                 | 15 +++-
 src/Backends/Swoole/Process.php             | 70 +++++++++++-----
 tests/Backends/Swoole/CoroutineTest.php     |  2 +-
 tests/Backends/Swoole/ProcessTest.php       | 88 +++++++++++++++++++++
 tests/BootstrapAggregatorTest.php           | 11 ++-
 tests/Classifiers/OneVsRestTest.php         | 13 ++-
 tests/Classifiers/RandomForestTest.php      | 13 ++-
 tests/CommitteeMachineTest.php              | 11 ++-
 tests/CrossValidation/KFoldTest.php         | 13 ++-
 tests/CrossValidation/LeavePOutTest.php     | 13 ++-
 tests/CrossValidation/MonteCarloTest.php    | 13 ++-
 tests/DataProvider/BackendProviderTrait.php | 36 +++++++++
 tests/GridSearchTest.php                    | 11 ++-
 tests/SwooleProcessBackend.php              | 24 ------
 15 files changed, 260 insertions(+), 76 deletions(-)
 create mode 100644 tests/Backends/Swoole/ProcessTest.php
 create mode 100644 tests/DataProvider/BackendProviderTrait.php
 delete mode 100644 tests/SwooleProcessBackend.php

diff --git a/composer.json b/composer.json
index 8cb313510..0f34eedb4 100644
--- a/composer.json
+++ b/composer.json
@@ -49,7 +49,8 @@
         "phpstan/extension-installer": "^1.0",
         "phpstan/phpstan": "^1.0",
         "phpstan/phpstan-phpunit": "^1.0",
-        "phpunit/phpunit": "^9.0"
+        "phpunit/phpunit": "^9.0",
+        "swoole/ide-helper": "^5.1"
     },
     "suggest": {
         "ext-tensor": "For fast Matrix/Vector computing",
diff --git a/phpunit.xml b/phpunit.xml
index 33e100832..54289bc72 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,5 +1,18 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" backupGlobals="false" backupStaticAttributes="false" bootstrap="vendor/autoload.php" colors="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" forceCoversAnnotation="true" processIsolation="false" stopOnFailure="false" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+<phpunit
+  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  backupGlobals="false"
+  backupStaticAttributes="false"
+  bootstrap="vendor/autoload.php"
+  colors="true"
+  convertErrorsToExceptions="true"
+  convertNoticesToExceptions="true"
+  convertWarningsToExceptions="true"
+  forceCoversAnnotation="true"
+  processIsolation="false"
+  stopOnFailure="false"
+  xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+>
   <coverage processUncoveredFiles="true">
     <include>
       <directory suffix=".php">src</directory>
diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
index b464ac9f8..c0979cb77 100644
--- a/src/Backends/Swoole/Process.php
+++ b/src/Backends/Swoole/Process.php
@@ -18,16 +18,26 @@
  */
 class Process implements Backend
 {
+    /**
+     * Swoole accepts values between 0.2 and 1
+     */
+    const HASH_COLLISIONS_ALLOWED = 0.25;
+
     /**
      * The queue of tasks to be processed in parallel.
      */
     protected array $queue = [];
 
-    private $cpus;
+    private int $serialiedRowLength;
 
-    public function __construct()
-    {
-        $this->cpus = swoole_cpu_num();
+    private int $workersCount;
+
+    public function __construct(
+        int $serialiedRowLength = 65536,
+        ?int $workersCount = null,
+    ) {
+        $this->serialiedRowLength = $serialiedRowLength;
+        $this->workersCount = $workersCount ?? swoole_cpu_num();
     }
 
     /**
@@ -61,40 +71,65 @@ public function enqueue(Task $task, ?callable $after = null, $context = null) :
      */
     public function process() : array
     {
-        $resultsTable = new Table(count($this->queue) * 2);
-        $resultsTable->column('result', Table::TYPE_FLOAT);
+        $resultsTable = new Table(count($this->queue), self::HASH_COLLISIONS_ALLOWED);
+        $resultsTable->column('result', Table::TYPE_STRING, $this->serialiedRowLength);
         $resultsTable->create();
 
-        $workersTable = new Table($this->cpus);
+        $workersTable = new Table($this->workersCount, self::HASH_COLLISIONS_ALLOWED);
         $workersTable->column('working', Table::TYPE_INT);
         $workersTable->create();
 
-        $pool = new Pool($this->cpus);
+        $pool = new Pool($this->workersCount);
+
         $pool->on('WorkerStart', function (Pool $pool, $workerId) use ($resultsTable, $workersTable) {
             try {
                 if (!$workersTable->exist($workerId)) {
-                    $workersTable->set($workerId, [
+                    if (!$workersTable->set($workerId, [
                         'working' => 1,
-                    ]);
+                    ])) {
+                        throw new RuntimeException('Unable to store worker status in the shared memory table');
+                    }
 
-                    for ($i = $workerId; $i < count($this->queue); $i += $this->cpus) {
+                    for ($i = $workerId; $i < count($this->queue); $i += $this->workersCount) {
                         if (!$resultsTable->exist($i)) {
-                            $resultsTable->set($i, [
-                                'result' => $this->queue[$i](),
-                            ]);
+                            $result = $this->queue[$i]();
+
+                            if (!$resultsTable->set($i, [
+                                'result' => serialize($result),
+                            ])) {
+                                throw new RuntimeException('Unable to store task result in the shared memory table');
+                            }
                         }
                     }
                 }
             } finally {
+                // Shuts down only the current worker. Tells Pool to not
+                // create a new worker
                 $pool->shutdown();
             }
         });
+
+        // This is blocking, waits until all processes finish.
         $pool->start();
 
         $results = [];
 
         for ($i = 0; $i < count($this->queue); $i += 1) {
-            $results[] = $resultsTable->get($i, 'result');
+            $serialized = $resultsTable->get($i, 'result');
+            $unserialized = unserialize($serialized);
+
+            if (false === $unserialized) {
+                // Task needs to be repeated due to hash collision in the Table
+                // That should be at most HASH_COLLISIONS_ALLOWED, usually less
+                //
+                // If 'false' was serialized, then the task will be redone
+                // unnecessarily. That is the price we have to pay for the lack
+                // of proper error handling in 'unserialize'. If you disagree
+                // or have some better idea, please open an issue on GitHub. ;)
+                $results[] = $this->queue[$i]();
+            } else {
+                $results[] = $unserialized;
+            }
         }
 
         return $results;
@@ -119,9 +154,4 @@ public function __toString() : string
     {
         return 'Swoole\\Process';
     }
-
-    private static function nextPowerOf2($number)
-    {
-        return pow(2, ceil(log($number,2)));
-    }
 }
diff --git a/tests/Backends/Swoole/CoroutineTest.php b/tests/Backends/Swoole/CoroutineTest.php
index f8ab50dd7..c3cb1ab7a 100644
--- a/tests/Backends/Swoole/CoroutineTest.php
+++ b/tests/Backends/Swoole/CoroutineTest.php
@@ -46,7 +46,7 @@ protected function setUp() : void
     /**
      * @after
      */
-    protected function tearDown(): void
+    protected function tearDown() : void
     {
         Event::wait();
     }
diff --git a/tests/Backends/Swoole/ProcessTest.php b/tests/Backends/Swoole/ProcessTest.php
new file mode 100644
index 000000000..cc80b012c
--- /dev/null
+++ b/tests/Backends/Swoole/ProcessTest.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace Rubix\ML\Tests\Backends\Swoole;
+
+use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Tasks\Task;
+use PHPUnit\Framework\TestCase;
+use Swoole\Event;
+
+/**
+ * @group Backends
+ * @group Swoole
+ * @covers \Rubix\ML\Backends\Swoole
+ */
+class ProcessTest extends TestCase
+{
+    /**
+     * @var \Rubix\ML\Backends\Swoole\Process
+     */
+    protected $backend;
+
+    /**
+     * @param int $i
+     * @return int
+     */
+    public static function foo(int $i) : int
+    {
+        return $i * 2;
+    }
+
+    /**
+     * @before
+     */
+    protected function setUp() : void
+    {
+        if (!extension_loaded('openswoole') && !extension_loaded('swoole')) {
+            $this->markTestSkipped(
+                'Swoole/OpenSwoole extension is not available.'
+            );
+        }
+
+        $this->backend = new SwooleProcessBackend();
+    }
+
+    /**
+     * @after
+     */
+    protected function tearDown() : void
+    {
+        Event::wait();
+    }
+
+    /**
+     * @test
+     */
+    public function build() : void
+    {
+        $this->assertInstanceOf(SwooleProcessBackend::class, $this->backend);
+        $this->assertInstanceOf(Backend::class, $this->backend);
+    }
+
+    /**
+     * @test
+     */
+    public function enqueueProcess() : void
+    {
+        for ($i = 0; $i < 10; ++$i) {
+            $this->backend->enqueue(new Task([self::class, 'foo'], [$i]));
+        }
+
+        $results = $this->backend->process();
+
+        $this->assertCount(10, $results);
+        $this->assertEquals([
+            0,
+            2,
+            4,
+            6,
+            8,
+            10,
+            12,
+            14,
+            16,
+            18,
+        ], $results);
+    }
+}
diff --git a/tests/BootstrapAggregatorTest.php b/tests/BootstrapAggregatorTest.php
index 2a17276a7..d3cf83cb9 100644
--- a/tests/BootstrapAggregatorTest.php
+++ b/tests/BootstrapAggregatorTest.php
@@ -7,7 +7,6 @@
 use Rubix\ML\Estimator;
 use Rubix\ML\Persistable;
 use Rubix\ML\EstimatorType;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Datasets\Unlabeled;
 use Rubix\ML\BootstrapAggregator;
 use Rubix\ML\Regressors\RegressionTree;
@@ -15,6 +14,8 @@
 use Rubix\ML\CrossValidation\Metrics\RSquared;
 use Rubix\ML\Exceptions\RuntimeException;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group MetaEstimators
@@ -22,6 +23,8 @@
  */
 class BootstrapAggregatorTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const TRAIN_SIZE = 512;
 
     protected const TEST_SIZE = 256;
@@ -111,11 +114,13 @@ public function params() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function trainPredict() : void
+    public function trainPredict(Backend $backend) : void
     {
-        $this->estimator->setBackend(new Serial());
+        $this->estimator->setBackend($backend);
 
         $training = $this->generator->generate(self::TRAIN_SIZE);
         $testing = $this->generator->generate(self::TEST_SIZE);
diff --git a/tests/Classifiers/OneVsRestTest.php b/tests/Classifiers/OneVsRestTest.php
index 271e44c52..9b3353218 100644
--- a/tests/Classifiers/OneVsRestTest.php
+++ b/tests/Classifiers/OneVsRestTest.php
@@ -9,7 +9,6 @@
 use Rubix\ML\Persistable;
 use Rubix\ML\Probabilistic;
 use Rubix\ML\EstimatorType;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Datasets\Unlabeled;
 use Rubix\ML\Classifiers\OneVsRest;
 use Rubix\ML\Classifiers\GaussianNB;
@@ -18,6 +17,8 @@
 use Rubix\ML\Datasets\Generators\Agglomerate;
 use Rubix\ML\Exceptions\RuntimeException;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group Classifiers
@@ -25,6 +26,8 @@
  */
 class OneVsRestTest extends TestCase
 {
+    use BackendProviderTrait;
+
     /**
      * The number of samples in the training set.
      *
@@ -81,8 +84,6 @@ protected function setUp() : void
 
         $this->estimator = new OneVsRest(new GaussianNB());
 
-        $this->estimator->setBackend(new Serial());
-
         $this->metric = new FBeta();
 
         srand(self::RANDOM_SEED);
@@ -139,10 +140,14 @@ public function params() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function trainPredictProba() : void
+    public function trainPredictProba(Backend $backend) : void
     {
+        $this->estimator->setBackend($backend);
+
         $training = $this->generator->generate(self::TRAIN_SIZE);
         $testing = $this->generator->generate(self::TEST_SIZE);
 
diff --git a/tests/Classifiers/RandomForestTest.php b/tests/Classifiers/RandomForestTest.php
index c1caf5358..34d5c4d68 100644
--- a/tests/Classifiers/RandomForestTest.php
+++ b/tests/Classifiers/RandomForestTest.php
@@ -9,7 +9,6 @@
 use Rubix\ML\Probabilistic;
 use Rubix\ML\RanksFeatures;
 use Rubix\ML\EstimatorType;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Datasets\Unlabeled;
 use Rubix\ML\Classifiers\RandomForest;
 use Rubix\ML\Datasets\Generators\Blob;
@@ -19,6 +18,8 @@
 use Rubix\ML\Exceptions\InvalidArgumentException;
 use Rubix\ML\Exceptions\RuntimeException;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group Classifiers
@@ -26,6 +27,8 @@
  */
 class RandomForestTest extends TestCase
 {
+    use BackendProviderTrait;
+
     /**
      * The number of samples in the training set.
      *
@@ -82,8 +85,6 @@ protected function setUp() : void
 
         $this->estimator = new RandomForest(new ClassificationTree(3), 50, 0.2, true);
 
-        $this->estimator->setBackend(new Serial());
-
         $this->metric = new FBeta();
 
         srand(self::RANDOM_SEED);
@@ -154,10 +155,14 @@ public function params() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function trainPredictImportances() : void
+    public function trainPredictImportances(Backend $backend) : void
     {
+        $this->estimator->setBackend($backend);
+
         $training = $this->generator->generate(self::TRAIN_SIZE);
         $testing = $this->generator->generate(self::TEST_SIZE);
 
diff --git a/tests/CommitteeMachineTest.php b/tests/CommitteeMachineTest.php
index a9330c86f..fde97ec7f 100644
--- a/tests/CommitteeMachineTest.php
+++ b/tests/CommitteeMachineTest.php
@@ -8,7 +8,6 @@
 use Rubix\ML\Estimator;
 use Rubix\ML\Persistable;
 use Rubix\ML\EstimatorType;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\CommitteeMachine;
 use Rubix\ML\Datasets\Unlabeled;
 use Rubix\ML\Classifiers\GaussianNB;
@@ -20,6 +19,8 @@
 use Rubix\ML\Exceptions\InvalidArgumentException;
 use Rubix\ML\Exceptions\RuntimeException;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group MetaEstimators
@@ -27,6 +28,8 @@
  */
 class CommitteeMachineTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const TRAIN_SIZE = 512;
 
     protected const TEST_SIZE = 256;
@@ -131,11 +134,13 @@ public function params() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function trainPredict() : void
+    public function trainPredict(Backend $backend) : void
     {
-        $this->estimator->setBackend(new Serial());
+        $this->estimator->setBackend($backend);
 
         $training = $this->generator->generate(self::TRAIN_SIZE);
         $testing = $this->generator->generate(self::TEST_SIZE);
diff --git a/tests/CrossValidation/KFoldTest.php b/tests/CrossValidation/KFoldTest.php
index 7d917fd7b..496e8d1e9 100644
--- a/tests/CrossValidation/KFoldTest.php
+++ b/tests/CrossValidation/KFoldTest.php
@@ -3,7 +3,6 @@
 namespace Rubix\ML\Tests\CrossValidation;
 
 use Rubix\ML\Parallel;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\CrossValidation\KFold;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\CrossValidation\Validator;
@@ -11,6 +10,8 @@
 use Rubix\ML\Datasets\Generators\Agglomerate;
 use Rubix\ML\CrossValidation\Metrics\Accuracy;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group Validators
@@ -18,6 +19,8 @@
  */
 class KFoldTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const DATASET_SIZE = 50;
 
     /**
@@ -54,8 +57,6 @@ protected function setUp() : void
 
         $this->validator = new KFold(10);
 
-        $this->validator->setBackend(new Serial());
-
         $this->metric = new Accuracy();
     }
 
@@ -70,10 +71,14 @@ public function build() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function test() : void
+    public function test(Backend $backend) : void
     {
+        $this->validator->setBackend($backend);
+
         [$min, $max] = $this->metric->range()->list();
 
         $dataset = $this->generator->generate(self::DATASET_SIZE);
diff --git a/tests/CrossValidation/LeavePOutTest.php b/tests/CrossValidation/LeavePOutTest.php
index afda69842..9f15d2f88 100644
--- a/tests/CrossValidation/LeavePOutTest.php
+++ b/tests/CrossValidation/LeavePOutTest.php
@@ -3,7 +3,6 @@
 namespace Rubix\ML\Tests\CrossValidation;
 
 use Rubix\ML\Parallel;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\CrossValidation\LeavePOut;
 use Rubix\ML\CrossValidation\Validator;
@@ -11,6 +10,8 @@
 use Rubix\ML\Datasets\Generators\Agglomerate;
 use Rubix\ML\CrossValidation\Metrics\Accuracy;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group Validators
@@ -18,6 +19,8 @@
  */
 class LeavePOutTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const DATASET_SIZE = 50;
 
     /**
@@ -54,8 +57,6 @@ protected function setUp() : void
 
         $this->validator = new LeavePOut(10);
 
-        $this->validator->setBackend(new Serial());
-
         $this->metric = new Accuracy();
     }
 
@@ -70,10 +71,14 @@ public function build() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function test() : void
+    public function test(Backend $backend) : void
     {
+        $this->validator->setBackend($backend);
+
         [$min, $max] = $this->metric->range()->list();
 
         $dataset = $this->generator->generate(self::DATASET_SIZE);
diff --git a/tests/CrossValidation/MonteCarloTest.php b/tests/CrossValidation/MonteCarloTest.php
index bc254b0b2..61a05ae6e 100644
--- a/tests/CrossValidation/MonteCarloTest.php
+++ b/tests/CrossValidation/MonteCarloTest.php
@@ -3,7 +3,6 @@
 namespace Rubix\ML\Tests\CrossValidation;
 
 use Rubix\ML\Parallel;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\CrossValidation\Validator;
 use Rubix\ML\CrossValidation\MonteCarlo;
@@ -11,6 +10,8 @@
 use Rubix\ML\Datasets\Generators\Agglomerate;
 use Rubix\ML\CrossValidation\Metrics\Accuracy;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group Validators
@@ -18,6 +19,8 @@
  */
 class MonteCarloTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const DATASET_SIZE = 50;
 
     /**
@@ -54,8 +57,6 @@ protected function setUp() : void
 
         $this->validator = new MonteCarlo(3, 0.2);
 
-        $this->validator->setBackend(new Serial());
-
         $this->metric = new Accuracy();
     }
 
@@ -70,10 +71,14 @@ public function build() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function test() : void
+    public function test(Backend $backend) : void
     {
+        $this->validator->setBackend($backend);
+
         [$min, $max] = $this->metric->range()->list();
 
         $dataset = $this->generator->generate(self::DATASET_SIZE);
diff --git a/tests/DataProvider/BackendProviderTrait.php b/tests/DataProvider/BackendProviderTrait.php
new file mode 100644
index 000000000..7207532df
--- /dev/null
+++ b/tests/DataProvider/BackendProviderTrait.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Rubix\ML\Tests\DataProvider;
+
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Serial;
+use Rubix\ML\Backends\Amp as AmpBackend;
+use Rubix\ML\Backends\Swoole\Coroutine as SwooleCoroutineBackend;
+use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+
+trait BackendProviderTrait
+{
+    /**
+     * @return array<Backend>
+     */
+    public static function provideBackends() : array
+    {
+        $backends = [];
+
+        $serialBackend = new Serial();
+        $backends[(string) $serialBackend] = [$serialBackend];
+
+        $ampBackend = new AmpBackend();
+        $backends[(string) $ampBackend] = [$ampBackend];
+
+        if (extension_loaded('swoole') || extension_loaded('openswoole')) {
+            $swooleCoroutineBackend = new SwooleCoroutineBackend();
+            $backends[(string) $swooleCoroutineBackend] = [$swooleCoroutineBackend];
+
+            $swooleProcessBackend = new SwooleProcessBackend();
+            $backends[(string) $swooleProcessBackend] = [$swooleProcessBackend];
+        }
+
+        return $backends;
+    }
+}
diff --git a/tests/GridSearchTest.php b/tests/GridSearchTest.php
index a2a2c736a..b67973062 100644
--- a/tests/GridSearchTest.php
+++ b/tests/GridSearchTest.php
@@ -9,7 +9,6 @@
 use Rubix\ML\GridSearch;
 use Rubix\ML\Persistable;
 use Rubix\ML\EstimatorType;
-use Rubix\ML\Backends\Serial;
 use Rubix\ML\Loggers\BlackHole;
 use Rubix\ML\CrossValidation\HoldOut;
 use Rubix\ML\Kernels\Distance\Euclidean;
@@ -20,6 +19,8 @@
 use Rubix\ML\Datasets\Generators\Agglomerate;
 use Rubix\ML\CrossValidation\Metrics\Accuracy;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @group MetaEstimators
@@ -27,6 +28,8 @@
  */
 class GridSearchTest extends TestCase
 {
+    use BackendProviderTrait;
+
     protected const TRAIN_SIZE = 512;
 
     protected const TEST_SIZE = 256;
@@ -121,12 +124,14 @@ public function params() : void
     }
 
     /**
+     * @dataProvider provideBackends
      * @test
+     * @param Backend $backend
      */
-    public function trainPredictBest() : void
+    public function trainPredictBest(Backend $backend) : void
     {
         $this->estimator->setLogger(new BlackHole());
-        $this->estimator->setBackend(new Serial());
+        $this->estimator->setBackend($backend);
 
         $training = $this->generator->generate(self::TRAIN_SIZE);
         $testing = $this->generator->generate(self::TEST_SIZE);
diff --git a/tests/SwooleProcessBackend.php b/tests/SwooleProcessBackend.php
deleted file mode 100644
index f2d1653d8..000000000
--- a/tests/SwooleProcessBackend.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-namespace Rubix\ML\Tests\Backends\Swoole;
-
-require_once __DIR__.'/../vendor/autoload.php';
-
-use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
-use Rubix\ML\Backends\Backend;
-use Rubix\ML\Backends\Tasks\Task;
-use PHPUnit\Framework\TestCase;
-use Swoole\Event;
-
-$backend = new SwooleProcessBackend();
-
-for ($i = 0; $i < 1000; ++$i) {
-    $backend->enqueue(new Task(function ($input) {
-        return $input * 2;
-    }, [$i]));
-}
-
-$results = $backend->process();
-
-var_dump(count($results));
-var_dump($results);

From d8fe0ed3b9603744ba447db5bc97a420d69130db Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 16:22:57 +0100
Subject: [PATCH 05/18] chore(swoole): make sure coroutines are at the root of
 the scheduler

---
 src/Backends/Swoole/Coroutine.php | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/src/Backends/Swoole/Coroutine.php b/src/Backends/Swoole/Coroutine.php
index bf9341124..18c25e188 100644
--- a/src/Backends/Swoole/Coroutine.php
+++ b/src/Backends/Swoole/Coroutine.php
@@ -4,8 +4,8 @@
 
 use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Tasks\Task;
-
-use function Swoole\Coroutine\batch;
+use RuntimeException;
+use Swoole\Coroutine\Scheduler;
 
 /**
  * Swoole
@@ -26,13 +26,6 @@ class Coroutine implements Backend
         //
     ];
 
-    protected float $timeout;
-
-    public function __construct(float $timeout = -1)
-    {
-        $this->timeout = $timeout;
-    }
-
     /**
      * Queue up a deferred task for backend processing.
      *
@@ -64,7 +57,23 @@ public function enqueue(Task $task, ?callable $after = null, $context = null) :
      */
     public function process() : array
     {
-        $results = batch($this->queue, $this->timeout);
+        /**
+         * Swoole promises that all the coroutines added to the root of the
+         * scheduler will be executed in parallel.
+         */
+        $scheduler = new Scheduler();
+
+        $results = [];
+
+        foreach ($this->queue as $callback) {
+            $scheduler->add(function () use ($callback, &$results) {
+                $results[] = $callback();
+            });
+        }
+
+        if (!$scheduler->start()) {
+            throw new RuntimeException('Not all coroutines finished successfully');
+        }
 
         $this->queue = [];
 

From 0c08ec51529c1a2a2bca99e129a675cfc18d0f9c Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 17:55:52 +0100
Subject: [PATCH 06/18] chore(swoole): set affinity / bind worker to a specific
 CPU core

---
 src/Backends/Swoole/Process.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
index c0979cb77..5275133d1 100644
--- a/src/Backends/Swoole/Process.php
+++ b/src/Backends/Swoole/Process.php
@@ -83,6 +83,9 @@ public function process() : array
 
         $pool->on('WorkerStart', function (Pool $pool, $workerId) use ($resultsTable, $workersTable) {
             try {
+                $process = $pool->getProcess();
+                $process->setAffinity([$workerId]);
+
                 if (!$workersTable->exist($workerId)) {
                     if (!$workersTable->set($workerId, [
                         'working' => 1,

From b69296abf9b8d126a73511a760c7c36221bddce1 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 18:46:42 +0100
Subject: [PATCH 07/18] chore(swoole): use igbinary if available

---
 benchmarks/Classifiers/RandomForestBench.php | 26 +++++++++++---------
 src/Backends/Swoole/IgbinarySerializer.php   | 16 ++++++++++++
 src/Backends/Swoole/PhpSerializer.php        | 16 ++++++++++++
 src/Backends/Swoole/Process.php              | 18 ++++++++++++--
 src/Backends/Swoole/Serializer.php           | 10 ++++++++
 5 files changed, 72 insertions(+), 14 deletions(-)
 create mode 100644 src/Backends/Swoole/IgbinarySerializer.php
 create mode 100644 src/Backends/Swoole/PhpSerializer.php
 create mode 100644 src/Backends/Swoole/Serializer.php

diff --git a/benchmarks/Classifiers/RandomForestBench.php b/benchmarks/Classifiers/RandomForestBench.php
index 1a03a9fc1..f7263ce3f 100644
--- a/benchmarks/Classifiers/RandomForestBench.php
+++ b/benchmarks/Classifiers/RandomForestBench.php
@@ -2,6 +2,7 @@
 
 namespace Rubix\ML\Benchmarks\Classifiers;
 
+use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
 use Rubix\ML\Classifiers\RandomForest;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\Classifiers\ClassificationTree;
@@ -45,6 +46,7 @@ public function setUpContinuous() : void
         $this->testing = $generator->generate(self::TESTING_SIZE);
 
         $this->estimator = new RandomForest(new ClassificationTree(30));
+        // $this->estimator->setBackend(new SwooleProcessBackend());
     }
 
     public function setUpCategorical() : void
@@ -78,16 +80,16 @@ public function continuous() : void
         $this->estimator->predict($this->testing);
     }
 
-    /**
-     * @Subject
-     * @Iterations(5)
-     * @BeforeMethods({"setUpCategorical"})
-     * @OutputTimeUnit("seconds", precision=3)
-     */
-    public function categorical() : void
-    {
-        $this->estimator->train($this->training);
-
-        $this->estimator->predict($this->testing);
-    }
+    // /**
+    //  * @Subject
+    //  * @Iterations(5)
+    //  * @BeforeMethods({"setUpCategorical"})
+    //  * @OutputTimeUnit("seconds", precision=3)
+    //  */
+    // public function categorical() : void
+    // {
+    //     $this->estimator->train($this->training);
+
+    //     $this->estimator->predict($this->testing);
+    // }
 }
diff --git a/src/Backends/Swoole/IgbinarySerializer.php b/src/Backends/Swoole/IgbinarySerializer.php
new file mode 100644
index 000000000..6bdcf01d4
--- /dev/null
+++ b/src/Backends/Swoole/IgbinarySerializer.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Rubix\ML\Backends\Swoole;
+
+class IgbinarySerializer implements Serializer
+{
+    public function serialize(mixed $value) : string
+    {
+        return igbinary_serialize($value);
+    }
+
+    public function unserialize(string $data) : mixed
+    {
+        return igbinary_unserialize($data);
+    }
+}
diff --git a/src/Backends/Swoole/PhpSerializer.php b/src/Backends/Swoole/PhpSerializer.php
new file mode 100644
index 000000000..79bdc074d
--- /dev/null
+++ b/src/Backends/Swoole/PhpSerializer.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Rubix\ML\Backends\Swoole;
+
+class PhpSerializer implements Serializer
+{
+    public function serialize(mixed $value) : string
+    {
+        return serialize($value);
+    }
+
+    public function unserialize(string $data) : mixed
+    {
+        return unserialize($data);
+    }
+}
diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
index 5275133d1..b97b5a85e 100644
--- a/src/Backends/Swoole/Process.php
+++ b/src/Backends/Swoole/Process.php
@@ -32,10 +32,23 @@ class Process implements Backend
 
     private int $workersCount;
 
+    private Serializer $serializer;
+
     public function __construct(
         int $serialiedRowLength = 65536,
         ?int $workersCount = null,
+        ?Serializer $serializer = null,
     ) {
+        if ($serializer) {
+            $this->serializer = $serializer;
+        } else {
+            if (extension_loaded('igbinary')) {
+                $this->serializer = new IgbinarySerializer();
+            } else {
+                $this->serializer = new PhpSerializer();
+            }
+        }
+
         $this->serialiedRowLength = $serialiedRowLength;
         $this->workersCount = $workersCount ?? swoole_cpu_num();
     }
@@ -96,9 +109,10 @@ public function process() : array
                     for ($i = $workerId; $i < count($this->queue); $i += $this->workersCount) {
                         if (!$resultsTable->exist($i)) {
                             $result = $this->queue[$i]();
+                            $serialized = $this->serializer->serialize($result);
 
                             if (!$resultsTable->set($i, [
-                                'result' => serialize($result),
+                                'result' => $serialized,
                             ])) {
                                 throw new RuntimeException('Unable to store task result in the shared memory table');
                             }
@@ -119,7 +133,7 @@ public function process() : array
 
         for ($i = 0; $i < count($this->queue); $i += 1) {
             $serialized = $resultsTable->get($i, 'result');
-            $unserialized = unserialize($serialized);
+            $unserialized = $this->serializer->unserialize($serialized);
 
             if (false === $unserialized) {
                 // Task needs to be repeated due to hash collision in the Table
diff --git a/src/Backends/Swoole/Serializer.php b/src/Backends/Swoole/Serializer.php
new file mode 100644
index 000000000..711dead90
--- /dev/null
+++ b/src/Backends/Swoole/Serializer.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Rubix\ML\Backends\Swoole;
+
+interface Serializer
+{
+    public function serialize(mixed $value) : string;
+
+    public function unserialize(string $data) : mixed;
+}

From 26959637944bf1b3243dcc88dfd7e99e52b3bbc4 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 18:47:02 +0100
Subject: [PATCH 08/18] fix: remove comment

---
 benchmarks/Classifiers/RandomForestBench.php | 24 ++++++++++----------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/benchmarks/Classifiers/RandomForestBench.php b/benchmarks/Classifiers/RandomForestBench.php
index f7263ce3f..4d524cd73 100644
--- a/benchmarks/Classifiers/RandomForestBench.php
+++ b/benchmarks/Classifiers/RandomForestBench.php
@@ -80,16 +80,16 @@ public function continuous() : void
         $this->estimator->predict($this->testing);
     }
 
-    // /**
-    //  * @Subject
-    //  * @Iterations(5)
-    //  * @BeforeMethods({"setUpCategorical"})
-    //  * @OutputTimeUnit("seconds", precision=3)
-    //  */
-    // public function categorical() : void
-    // {
-    //     $this->estimator->train($this->training);
-
-    //     $this->estimator->predict($this->testing);
-    // }
+    /**
+     * @Subject
+     * @Iterations(5)
+     * @BeforeMethods({"setUpCategorical"})
+     * @OutputTimeUnit("seconds", precision=3)
+     */
+    public function categorical() : void
+    {
+        $this->estimator->train($this->training);
+
+        $this->estimator->predict($this->testing);
+    }
 }

From d4666f50497fdd360566836fbb9b28ad4d8a5ead Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 18:52:22 +0100
Subject: [PATCH 09/18] fix(swoole): worker cpu affinity

---
 src/Backends/Swoole/Process.php | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
index b97b5a85e..3e58e086e 100644
--- a/src/Backends/Swoole/Process.php
+++ b/src/Backends/Swoole/Process.php
@@ -28,15 +28,14 @@ class Process implements Backend
      */
     protected array $queue = [];
 
-    private int $serialiedRowLength;
+    private int $cpus;
 
-    private int $workersCount;
+    private int $serialiedRowLength;
 
     private Serializer $serializer;
 
     public function __construct(
         int $serialiedRowLength = 65536,
-        ?int $workersCount = null,
         ?Serializer $serializer = null,
     ) {
         if ($serializer) {
@@ -50,7 +49,6 @@ public function __construct(
         }
 
         $this->serialiedRowLength = $serialiedRowLength;
-        $this->workersCount = $workersCount ?? swoole_cpu_num();
     }
 
     /**
@@ -88,15 +86,19 @@ public function process() : array
         $resultsTable->column('result', Table::TYPE_STRING, $this->serialiedRowLength);
         $resultsTable->create();
 
-        $workersTable = new Table($this->workersCount, self::HASH_COLLISIONS_ALLOWED);
+        $workersTable = new Table($this->cpus, self::HASH_COLLISIONS_ALLOWED);
         $workersTable->column('working', Table::TYPE_INT);
         $workersTable->create();
 
-        $pool = new Pool($this->workersCount);
+        $pool = new Pool($this->cpus);
 
         $pool->on('WorkerStart', function (Pool $pool, $workerId) use ($resultsTable, $workersTable) {
             try {
                 $process = $pool->getProcess();
+
+                // Worker id is an integer that goes from 0 to the number of
+                // workers. There are "$this->cpu" workers spawned, so worker
+                // id should correspond to a specific core.
                 $process->setAffinity([$workerId]);
 
                 if (!$workersTable->exist($workerId)) {
@@ -106,7 +108,7 @@ public function process() : array
                         throw new RuntimeException('Unable to store worker status in the shared memory table');
                     }
 
-                    for ($i = $workerId; $i < count($this->queue); $i += $this->workersCount) {
+                    for ($i = $workerId; $i < count($this->queue); $i += $this->cpus) {
                         if (!$resultsTable->exist($i)) {
                             $result = $this->queue[$i]();
                             $serialized = $this->serializer->serialize($result);

From bfa97d1342bc0dd14549c423cc062cb9da9d184d Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 8 Jan 2024 18:53:14 +0100
Subject: [PATCH 10/18] fix(swoole): cpu num

---
 src/Backends/Swoole/Process.php | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
index 3e58e086e..bb0419827 100644
--- a/src/Backends/Swoole/Process.php
+++ b/src/Backends/Swoole/Process.php
@@ -38,6 +38,8 @@ public function __construct(
         int $serialiedRowLength = 65536,
         ?Serializer $serializer = null,
     ) {
+        $this->cpus = swoole_cpu_num();
+
         if ($serializer) {
             $this->serializer = $serializer;
         } else {

From 6c267bcec14dc6fee02df27db3ef97a0c7909747 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Fri, 12 Jan 2024 16:29:11 +0100
Subject: [PATCH 11/18] feat: scheduler improvements

---
 benchmarks/Classifiers/RandomForestBench.php  |  30 +--
 src/Backends/Swoole.php                       | 162 ++++++++++++++++
 src/Backends/Swoole/Coroutine.php             | 102 ----------
 src/Backends/Swoole/IgbinarySerializer.php    |  16 --
 src/Backends/Swoole/PhpSerializer.php         |  16 --
 src/Backends/Swoole/Process.php               | 178 ------------------
 src/Backends/Swoole/Serializer.php            |  10 -
 src/Serializers/Igbinary.php                  |  87 +++++++++
 .../SwooleExtensionIsLoaded.php               |  31 +++
 tests/Backends/Swoole/CoroutineTest.php       |  88 ---------
 .../ProcessTest.php => SwooleTest.php}        |  13 +-
 tests/DataProvider/BackendProviderTrait.php   |  15 +-
 12 files changed, 309 insertions(+), 439 deletions(-)
 create mode 100644 src/Backends/Swoole.php
 delete mode 100644 src/Backends/Swoole/Coroutine.php
 delete mode 100644 src/Backends/Swoole/IgbinarySerializer.php
 delete mode 100644 src/Backends/Swoole/PhpSerializer.php
 delete mode 100644 src/Backends/Swoole/Process.php
 delete mode 100644 src/Backends/Swoole/Serializer.php
 create mode 100644 src/Serializers/Igbinary.php
 create mode 100644 src/Specifications/SwooleExtensionIsLoaded.php
 delete mode 100644 tests/Backends/Swoole/CoroutineTest.php
 rename tests/Backends/{Swoole/ProcessTest.php => SwooleTest.php} (80%)

diff --git a/benchmarks/Classifiers/RandomForestBench.php b/benchmarks/Classifiers/RandomForestBench.php
index 4d524cd73..c1b02b817 100644
--- a/benchmarks/Classifiers/RandomForestBench.php
+++ b/benchmarks/Classifiers/RandomForestBench.php
@@ -2,7 +2,8 @@
 
 namespace Rubix\ML\Benchmarks\Classifiers;
 
-use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+use Rubix\ML\Backends\Amp;
+use Rubix\ML\Backends\Swoole as SwooleBackend;
 use Rubix\ML\Classifiers\RandomForest;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\Classifiers\ClassificationTree;
@@ -46,7 +47,8 @@ public function setUpContinuous() : void
         $this->testing = $generator->generate(self::TESTING_SIZE);
 
         $this->estimator = new RandomForest(new ClassificationTree(30));
-        // $this->estimator->setBackend(new SwooleProcessBackend());
+        $this->estimator->setBackend(new SwooleBackend());
+        // $this->estimator->setBackend(new Amp());
     }
 
     public function setUpCategorical() : void
@@ -80,16 +82,16 @@ public function continuous() : void
         $this->estimator->predict($this->testing);
     }
 
-    /**
-     * @Subject
-     * @Iterations(5)
-     * @BeforeMethods({"setUpCategorical"})
-     * @OutputTimeUnit("seconds", precision=3)
-     */
-    public function categorical() : void
-    {
-        $this->estimator->train($this->training);
-
-        $this->estimator->predict($this->testing);
-    }
+    // /**
+    //  * @Subject
+    //  * @Iterations(5)
+    //  * @BeforeMethods({"setUpCategorical"})
+    //  * @OutputTimeUnit("seconds", precision=3)
+    //  */
+    // public function categorical() : void
+    // {
+    //     $this->estimator->train($this->training);
+
+    //     $this->estimator->predict($this->testing);
+    // }
 }
diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
new file mode 100644
index 000000000..36946e593
--- /dev/null
+++ b/src/Backends/Swoole.php
@@ -0,0 +1,162 @@
+<?php
+
+namespace Rubix\ML\Backends;
+
+use Rubix\ML\Backends\Backend;
+use Rubix\ML\Backends\Tasks\Task;
+use Rubix\ML\Encoding;
+use Rubix\ML\Serializers\Serializer;
+use Rubix\ML\Serializers\Igbinary;
+use Rubix\ML\Serializers\Native;
+use Rubix\ML\Specifications\ExtensionIsLoaded;
+use RuntimeException;
+use Swoole\Atomic;
+use Swoole\Process;
+use Swoole\Process\Pool;
+use Swoole\Table;
+
+use function Swoole\Coroutine\run;
+
+/**
+ * Swoole
+ *
+ * Works both with Swoole and OpenSwoole.
+ *
+ * @category    Machine Learning
+ * @package     Rubix/ML
+ */
+class Swoole implements Backend
+{
+    /**
+     * Swoole accepts values between 0.2 and 1
+     */
+    const CONFLICT_PROPORTION = 0.25;
+
+    /**
+     * The queue of tasks to be processed in parallel.
+     */
+    protected array $queue = [];
+
+    private int $cpus;
+
+    private Serializer $serializer;
+
+    public function __construct(?Serializer $serializer = null)
+    {
+        $this->cpus = swoole_cpu_num();
+
+        if ($serializer) {
+            $this->serializer = $serializer;
+        } else {
+            if (ExtensionIsLoaded::with('igbinary')->passes()) {
+                $this->serializer = new Igbinary();
+            } else {
+                $this->serializer = new Native();
+            }
+        }
+    }
+
+    /**
+     * Queue up a deferred task for backend processing.
+     *
+     * @internal
+     *
+     * @param \Rubix\ML\Backends\Tasks\Task $task
+     * @param callable(mixed,mixed):void $after
+     * @param mixed $context
+     */
+    public function enqueue(Task $task, ?callable $after = null, $context = null) : void
+    {
+        $this->queue[] = function () use ($task, $after, $context) {
+            $result = $task();
+
+            if ($after) {
+                $after($result, $context);
+            }
+
+            return $result;
+        };
+    }
+
+    /**
+     * Process the queue and return the results.
+     *
+     * @internal
+     *
+     * @return mixed[]
+     */
+    public function process() : array
+    {
+        $results = [];
+
+        $finishedTasksAtomic = new Atomic();
+        $waitingAtomic = new Atomic();
+
+        $scheduledTasksTotal = count($this->queue);
+        $workerProcesses = [];
+
+        $currentCpu = 0;
+
+        while (($queueItem = array_shift($this->queue))) {
+            $workerProcess = new Process(
+                callback: function (Process $worker) use ($finishedTasksAtomic, $queueItem, $scheduledTasksTotal, $waitingAtomic) {
+                    try {
+                        $worker->exportSocket()->send(igbinary_serialize($queueItem()));
+                    } finally {
+                        $finishedTasksAtomic->add(1);
+
+                        if ($scheduledTasksTotal <= $finishedTasksAtomic->get()) {
+                            $waitingAtomic->wakeup();
+                        }
+                    }
+                },
+                enable_coroutine: true,
+                pipe_type: 1,
+                redirect_stdin_and_stdout: false,
+            );
+
+            $workerProcess->setAffinity([
+                $currentCpu,
+            ]);
+            $workerProcess->setBlocking(false);
+            $workerProcess->start();
+
+            $workerProcesses[] = $workerProcess;
+
+            $currentCpu = ($currentCpu + 1) % $this->cpus;
+        }
+
+        $waitingAtomic->wait(-1);
+
+        run(function () use (&$results, $workerProcesses) {
+            foreach ($workerProcesses as $workerProcess) {
+                $receivedData = $workerProcess->exportSocket()->recv();
+                $unserialized = igbinary_unserialize($receivedData);
+
+                $results[] = $unserialized;
+            }
+        });
+
+        return $results;
+    }
+
+    /**
+     * Flush the queue
+     */
+    public function flush() : void
+    {
+        $this->queue = [];
+    }
+
+    /**
+     * Return the string representation of the object.
+     *
+     * @internal
+     *
+     * @return string
+     */
+    public function __toString() : string
+    {
+        return 'Swoole\\Process';
+    }
+}
diff --git a/src/Backends/Swoole/Coroutine.php b/src/Backends/Swoole/Coroutine.php
deleted file mode 100644
index 18c25e188..000000000
--- a/src/Backends/Swoole/Coroutine.php
+++ /dev/null
@@ -1,102 +0,0 @@
-<?php
-
-namespace Rubix\ML\Backends\Swoole;
-
-use Rubix\ML\Backends\Backend;
-use Rubix\ML\Backends\Tasks\Task;
-use RuntimeException;
-use Swoole\Coroutine\Scheduler;
-
-/**
- * Swoole
- *
- * Works both with Swoole and OpenSwoole.
- *
- * @category    Machine Learning
- * @package     Rubix/ML
- */
-class Coroutine implements Backend
-{
-    /**
-     * The queue of tasks to be processed in parallel.
-     *
-     * @var list<callable>
-     */
-    protected array $queue = [
-        //
-    ];
-
-    /**
-     * Queue up a deferred task for backend processing.
-     *
-     * @internal
-     *
-     * @param \Rubix\ML\Backends\Tasks\Task $task
-     * @param callable(mixed,mixed):void $after
-     * @param mixed $context
-     */
-    public function enqueue(Task $task, ?callable $after = null, $context = null) : void
-    {
-        $this->queue[] = function () use ($task, $after, $context) {
-            $result = $task();
-
-            if ($after) {
-                $after($result, $context);
-            }
-
-            return $result;
-        };
-    }
-
-    /**
-     * Process the queue and return the results.
-     *
-     * @internal
-     *
-     * @return mixed[]
-     */
-    public function process() : array
-    {
-        /**
-         * Swoole promises that all the coroutines added to the root of the
-         * scheduler will be executed in parallel.
-         */
-        $scheduler = new Scheduler();
-
-        $results = [];
-
-        foreach ($this->queue as $callback) {
-            $scheduler->add(function () use ($callback, &$results) {
-                $results[] = $callback();
-            });
-        }
-
-        if (!$scheduler->start()) {
-            throw new RuntimeException('Not all coroutines finished successfully');
-        }
-
-        $this->queue = [];
-
-        return $results;
-    }
-
-    /**
-     * Flush the queue
-     */
-    public function flush() : void
-    {
-        $this->queue = [];
-    }
-
-    /**
-     * Return the string representation of the object.
-     *
-     * @internal
-     *
-     * @return string
-     */
-    public function __toString() : string
-    {
-        return 'Swoole\\Coroutine';
-    }
-}
diff --git a/src/Backends/Swoole/IgbinarySerializer.php b/src/Backends/Swoole/IgbinarySerializer.php
deleted file mode 100644
index 6bdcf01d4..000000000
--- a/src/Backends/Swoole/IgbinarySerializer.php
+++ /dev/null
@@ -1,16 +0,0 @@
-<?php
-
-namespace Rubix\ML\Backends\Swoole;
-
-class IgbinarySerializer implements Serializer
-{
-    public function serialize(mixed $value) : string
-    {
-        return igbinary_serialize($value);
-    }
-
-    public function unserialize(string $data) : mixed
-    {
-        return igbinary_unserialize($data);
-    }
-}
diff --git a/src/Backends/Swoole/PhpSerializer.php b/src/Backends/Swoole/PhpSerializer.php
deleted file mode 100644
index 79bdc074d..000000000
--- a/src/Backends/Swoole/PhpSerializer.php
+++ /dev/null
@@ -1,16 +0,0 @@
-<?php
-
-namespace Rubix\ML\Backends\Swoole;
-
-class PhpSerializer implements Serializer
-{
-    public function serialize(mixed $value) : string
-    {
-        return serialize($value);
-    }
-
-    public function unserialize(string $data) : mixed
-    {
-        return unserialize($data);
-    }
-}
diff --git a/src/Backends/Swoole/Process.php b/src/Backends/Swoole/Process.php
deleted file mode 100644
index bb0419827..000000000
--- a/src/Backends/Swoole/Process.php
+++ /dev/null
@@ -1,178 +0,0 @@
-<?php
-
-namespace Rubix\ML\Backends\Swoole;
-
-use Rubix\ML\Backends\Backend;
-use Rubix\ML\Backends\Tasks\Task;
-use RuntimeException;
-use Swoole\Process\Pool;
-use Swoole\Table;
-
-/**
- * Swoole
- *
- * Works both with Swoole and OpenSwoole.
- *
- * @category    Machine Learning
- * @package     Rubix/ML
- */
-class Process implements Backend
-{
-    /**
-     * Swoole accepts values between 0.2 and 1
-     */
-    const HASH_COLLISIONS_ALLOWED = 0.25;
-
-    /**
-     * The queue of tasks to be processed in parallel.
-     */
-    protected array $queue = [];
-
-    private int $cpus;
-
-    private int $serialiedRowLength;
-
-    private Serializer $serializer;
-
-    public function __construct(
-        int $serialiedRowLength = 65536,
-        ?Serializer $serializer = null,
-    ) {
-        $this->cpus = swoole_cpu_num();
-
-        if ($serializer) {
-            $this->serializer = $serializer;
-        } else {
-            if (extension_loaded('igbinary')) {
-                $this->serializer = new IgbinarySerializer();
-            } else {
-                $this->serializer = new PhpSerializer();
-            }
-        }
-
-        $this->serialiedRowLength = $serialiedRowLength;
-    }
-
-    /**
-     * Queue up a deferred task for backend processing.
-     *
-     * @internal
-     *
-     * @param \Rubix\ML\Backends\Tasks\Task $task
-     * @param callable(mixed,mixed):void $after
-     * @param mixed $context
-     */
-    public function enqueue(Task $task, ?callable $after = null, $context = null) : void
-    {
-        $this->queue[] = function () use ($task, $after, $context) {
-            $result = $task();
-
-            if ($after) {
-                $after($result, $context);
-            }
-
-            return $result;
-        };
-    }
-
-    /**
-     * Process the queue and return the results.
-     *
-     * @internal
-     *
-     * @return mixed[]
-     */
-    public function process() : array
-    {
-        $resultsTable = new Table(count($this->queue), self::HASH_COLLISIONS_ALLOWED);
-        $resultsTable->column('result', Table::TYPE_STRING, $this->serialiedRowLength);
-        $resultsTable->create();
-
-        $workersTable = new Table($this->cpus, self::HASH_COLLISIONS_ALLOWED);
-        $workersTable->column('working', Table::TYPE_INT);
-        $workersTable->create();
-
-        $pool = new Pool($this->cpus);
-
-        $pool->on('WorkerStart', function (Pool $pool, $workerId) use ($resultsTable, $workersTable) {
-            try {
-                $process = $pool->getProcess();
-
-                // Worker id is an integer that goes from 0 to the number of
-                // workers. There are "$this->cpu" workers spawned, so worker
-                // id should correspond to a specific core.
-                $process->setAffinity([$workerId]);
-
-                if (!$workersTable->exist($workerId)) {
-                    if (!$workersTable->set($workerId, [
-                        'working' => 1,
-                    ])) {
-                        throw new RuntimeException('Unable to store worker status in the shared memory table');
-                    }
-
-                    for ($i = $workerId; $i < count($this->queue); $i += $this->cpus) {
-                        if (!$resultsTable->exist($i)) {
-                            $result = $this->queue[$i]();
-                            $serialized = $this->serializer->serialize($result);
-
-                            if (!$resultsTable->set($i, [
-                                'result' => $serialized,
-                            ])) {
-                                throw new RuntimeException('Unable to store task result in the shared memory table');
-                            }
-                        }
-                    }
-                }
-            } finally {
-                // Shuts down only the current worker. Tells Pool to not
-                // create a new worker
-                $pool->shutdown();
-            }
-        });
-
-        // This is blocking, waits until all processes finish.
-        $pool->start();
-
-        $results = [];
-
-        for ($i = 0; $i < count($this->queue); $i += 1) {
-            $serialized = $resultsTable->get($i, 'result');
-            $unserialized = $this->serializer->unserialize($serialized);
-
-            if (false === $unserialized) {
-                // Task needs to be repeated due to hash collision in the Table
-                // That should be at most HASH_COLLISIONS_ALLOWED, usually less
-                //
-                // If 'false' was serialized, then the task will be redone
-                // unnecessarily. That is the price we have to pay for the lack
-                // of proper error handling in 'unserialize'. If you disagree
-                // or have some better idea, please open an issue on GitHub. ;)
-                $results[] = $this->queue[$i]();
-            } else {
-                $results[] = $unserialized;
-            }
-        }
-
-        return $results;
-    }
-
-    /**
-     * Flush the queue
-     */
-    public function flush() : void
-    {
-        $this->queue = [];
-    }
-
-    /**
-     * Return the string representation of the object.
-     *
-     * @internal
-     *
-     * @return string
-     */
-    public function __toString() : string
-    {
-        return 'Swoole\\Process';
-    }
-}
diff --git a/src/Backends/Swoole/Serializer.php b/src/Backends/Swoole/Serializer.php
deleted file mode 100644
index 711dead90..000000000
--- a/src/Backends/Swoole/Serializer.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-namespace Rubix\ML\Backends\Swoole;
-
-interface Serializer
-{
-    public function serialize(mixed $value) : string;
-
-    public function unserialize(string $data) : mixed;
-}
diff --git a/src/Serializers/Igbinary.php b/src/Serializers/Igbinary.php
new file mode 100644
index 000000000..7439b965c
--- /dev/null
+++ b/src/Serializers/Igbinary.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Rubix\ML\Serializers;
+
+use Rubix\ML\Encoding;
+use Rubix\ML\Persistable;
+use Rubix\ML\Exceptions\RuntimeException;
+use Rubix\ML\Specifications\ExtensionIsLoaded;
+use __PHP_Incomplete_Class;
+
+use function is_object;
+
+/**
+ * Igbinary
+ *
+ * Igbinary is a compact binary format that serves as a drop-in replacement for the native PHP serializer.
+ *
+ * @category    Machine Learning
+ * @package     Rubix/ML
+ * @author      Andrew DalPino
+ */
+class Igbinary implements Serializer
+{
+    public function __construct()
+    {
+        ExtensionIsLoaded::with('igbinary')->check();
+    }
+
+    /**
+     * Serialize a persistable object and return the data.
+     *
+     * @internal
+     *
+     * @param \Rubix\ML\Persistable $persistable
+     * @throws \Rubix\ML\Exceptions\RuntimeException
+     * @return \Rubix\ML\Encoding
+     */
+    public function serialize(Persistable $persistable) : Encoding
+    {
+        $data = igbinary_serialize($persistable);
+
+        if (!$data) {
+            throw new RuntimeException('Could not serialize data.');
+        }
+
+        return new Encoding($data);
+    }
+
+    /**
+     * Deserialize a persistable object and return it.
+     *
+     * @internal
+     *
+     * @param \Rubix\ML\Encoding $encoding
+     * @throws \Rubix\ML\Exceptions\RuntimeException
+     * @return \Rubix\ML\Persistable
+     */
+    public function deserialize(Encoding $encoding) : Persistable
+    {
+        $persistable = igbinary_unserialize($encoding);
+
+        if (!is_object($persistable)) {
+            throw new RuntimeException('deserialized data must be an object.');
+        }
+
+        if ($persistable instanceof __PHP_Incomplete_Class) {
+            throw new RuntimeException('Missing class for object data.');
+        }
+
+        if (!$persistable instanceof Persistable) {
+            throw new RuntimeException('deserialized object must'
+                . ' implement the Persistable interface.');
+        }
+
+        return $persistable;
+    }
+
+    /**
+     * Return the string representation of the object.
+     *
+     * @return string
+     */
+    public function __toString() : string
+    {
+        return 'Igbinary';
+    }
+}
\ No newline at end of file
diff --git a/src/Specifications/SwooleExtensionIsLoaded.php b/src/Specifications/SwooleExtensionIsLoaded.php
new file mode 100644
index 000000000..d2179ef51
--- /dev/null
+++ b/src/Specifications/SwooleExtensionIsLoaded.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Rubix\ML\Specifications;
+
+use Rubix\ML\Exceptions\MissingExtension;
+
+/**
+ * @internal
+ */
+class SwooleExtensionIsLoaded extends Specification
+{
+    public static function create() : self
+    {
+        return new self();
+    }
+
+    /**
+     * @throws \Rubix\ML\Exceptions\MissingExtension
+     */
+    public function check() : void
+    {
+        if (
+            ExtensionIsLoaded::with('swoole')->passes()
+            || ExtensionIsLoaded::with('openswoole')->passes()
+        ) {
+            return;
+        }
+
+        throw new MissingExtension('swoole');
+    }
+}
diff --git a/tests/Backends/Swoole/CoroutineTest.php b/tests/Backends/Swoole/CoroutineTest.php
deleted file mode 100644
index c3cb1ab7a..000000000
--- a/tests/Backends/Swoole/CoroutineTest.php
+++ /dev/null
@@ -1,88 +0,0 @@
-<?php
-
-namespace Rubix\ML\Tests\Backends\Swoole;
-
-use Rubix\ML\Backends\Swoole\Coroutine as SwooleCoroutineBackend;
-use Rubix\ML\Backends\Backend;
-use Rubix\ML\Backends\Tasks\Task;
-use PHPUnit\Framework\TestCase;
-use Swoole\Event;
-
-/**
- * @group Backends
- * @group Swoole
- * @covers \Rubix\ML\Backends\Swoole
- */
-class CoroutineTest extends TestCase
-{
-    /**
-     * @var \Rubix\ML\Backends\Swoole\Coroutine
-     */
-    protected $backend;
-
-    /**
-     * @param int $i
-     * @return int
-     */
-    public static function foo(int $i) : int
-    {
-        return $i * 2;
-    }
-
-    /**
-     * @before
-     */
-    protected function setUp() : void
-    {
-        if (!extension_loaded('openswoole') && !extension_loaded('swoole')) {
-            $this->markTestSkipped(
-                'Swoole/OpenSwoole extension is not available.'
-            );
-        }
-
-        $this->backend = new SwooleCoroutineBackend();
-    }
-
-    /**
-     * @after
-     */
-    protected function tearDown() : void
-    {
-        Event::wait();
-    }
-
-    /**
-     * @test
-     */
-    public function build() : void
-    {
-        $this->assertInstanceOf(SwooleCoroutineBackend::class, $this->backend);
-        $this->assertInstanceOf(Backend::class, $this->backend);
-    }
-
-    /**
-     * @test
-     */
-    public function enqueueProcess() : void
-    {
-        for ($i = 0; $i < 10; ++$i) {
-            $this->backend->enqueue(new Task([self::class, 'foo'], [$i]));
-        }
-
-        $results = $this->backend->process();
-
-        $this->assertCount(10, $results);
-        $this->assertEquals([
-            0,
-            2,
-            4,
-            6,
-            8,
-            10,
-            12,
-            14,
-            16,
-            18,
-        ], $results);
-    }
-}
diff --git a/tests/Backends/Swoole/ProcessTest.php b/tests/Backends/SwooleTest.php
similarity index 80%
rename from tests/Backends/Swoole/ProcessTest.php
rename to tests/Backends/SwooleTest.php
index cc80b012c..ece9e41a6 100644
--- a/tests/Backends/Swoole/ProcessTest.php
+++ b/tests/Backends/SwooleTest.php
@@ -1,11 +1,12 @@
 <?php
 
-namespace Rubix\ML\Tests\Backends\Swoole;
+namespace Rubix\ML\Tests\Backends;
 
-use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+use Rubix\ML\Backends\Swoole as SwooleBackend;
 use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Tasks\Task;
 use PHPUnit\Framework\TestCase;
+use Rubix\ML\Specifications\SwooleExtensionIsLoaded;
 use Swoole\Event;
 
 /**
@@ -13,7 +14,7 @@
  * @group Swoole
  * @covers \Rubix\ML\Backends\Swoole
  */
-class ProcessTest extends TestCase
+class SwooleTest extends TestCase
 {
     /**
      * @var \Rubix\ML\Backends\Swoole\Process
@@ -34,13 +35,13 @@ public static function foo(int $i) : int
      */
     protected function setUp() : void
     {
-        if (!extension_loaded('openswoole') && !extension_loaded('swoole')) {
+        if (!SwooleExtensionIsLoaded::create()->passes()) {
             $this->markTestSkipped(
                 'Swoole/OpenSwoole extension is not available.'
             );
         }
 
-        $this->backend = new SwooleProcessBackend();
+        $this->backend = new SwooleBackend();
     }
 
     /**
@@ -56,7 +57,7 @@ protected function tearDown() : void
      */
     public function build() : void
     {
-        $this->assertInstanceOf(SwooleProcessBackend::class, $this->backend);
+        $this->assertInstanceOf(SwooleBackend::class, $this->backend);
         $this->assertInstanceOf(Backend::class, $this->backend);
     }
 
diff --git a/tests/DataProvider/BackendProviderTrait.php b/tests/DataProvider/BackendProviderTrait.php
index 7207532df..f33d72a6a 100644
--- a/tests/DataProvider/BackendProviderTrait.php
+++ b/tests/DataProvider/BackendProviderTrait.php
@@ -4,9 +4,9 @@
 
 use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Serial;
-use Rubix\ML\Backends\Amp as AmpBackend;
-use Rubix\ML\Backends\Swoole\Coroutine as SwooleCoroutineBackend;
-use Rubix\ML\Backends\Swoole\Process as SwooleProcessBackend;
+use Rubix\ML\Backends\Amp;
+use Rubix\ML\Backends\Swoole;
+use Rubix\ML\Specifications\SwooleExtensionIsLoaded;
 
 trait BackendProviderTrait
 {
@@ -20,14 +20,11 @@ public static function provideBackends() : array
         $serialBackend = new Serial();
         $backends[(string) $serialBackend] = [$serialBackend];
 
-        $ampBackend = new AmpBackend();
+        $ampBackend = new Amp();
         $backends[(string) $ampBackend] = [$ampBackend];
 
-        if (extension_loaded('swoole') || extension_loaded('openswoole')) {
-            $swooleCoroutineBackend = new SwooleCoroutineBackend();
-            $backends[(string) $swooleCoroutineBackend] = [$swooleCoroutineBackend];
-
-            $swooleProcessBackend = new SwooleProcessBackend();
+        if (SwooleExtensionIsLoaded::create()->passes()) {
+            $swooleProcessBackend = new Swoole();
             $backends[(string) $swooleProcessBackend] = [$swooleProcessBackend];
         }
 

From 7b200f594422396781d699de0dd5f59e800b2ead Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Fri, 12 Jan 2024 16:36:39 +0100
Subject: [PATCH 12/18] style

---
 src/Backends/Swoole.php      | 5 -----
 src/Serializers/Igbinary.php | 2 +-
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 36946e593..8c528a183 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -2,18 +2,13 @@
 
 namespace Rubix\ML\Backends;
 
-use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Tasks\Task;
-use Rubix\ML\Encoding;
 use Rubix\ML\Serializers\Serializer;
 use Rubix\ML\Serializers\Igbinary;
 use Rubix\ML\Serializers\Native;
 use Rubix\ML\Specifications\ExtensionIsLoaded;
-use RuntimeException;
 use Swoole\Atomic;
 use Swoole\Process;
-use Swoole\Process\Pool;
-use Swoole\Table;
 
 use function Swoole\Coroutine\run;
 
diff --git a/src/Serializers/Igbinary.php b/src/Serializers/Igbinary.php
index 7439b965c..2c18ec348 100644
--- a/src/Serializers/Igbinary.php
+++ b/src/Serializers/Igbinary.php
@@ -84,4 +84,4 @@ public function __toString() : string
     {
         return 'Igbinary';
     }
-}
\ No newline at end of file
+}

From 1d75ce9a8ca418018fe70d7a3c32b237cd9e6826 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Fri, 12 Jan 2024 16:42:58 +0100
Subject: [PATCH 13/18] chore(swoole): remove unnecessary atomics

---
 src/Backends/Swoole.php | 24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 8c528a183..0c27bcb94 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -7,7 +7,6 @@
 use Rubix\ML\Serializers\Igbinary;
 use Rubix\ML\Serializers\Native;
 use Rubix\ML\Specifications\ExtensionIsLoaded;
-use Swoole\Atomic;
 use Swoole\Process;
 
 use function Swoole\Coroutine\run;
@@ -22,11 +21,6 @@
  */
 class Swoole implements Backend
 {
-    /**
-     * Swoole accepts values between 0.2 and 1
-     */
-    const CONFLICT_PROPORTION = 0.25;
-
     /**
      * The queue of tasks to be processed in parallel.
      */
@@ -84,26 +78,14 @@ public function process() : array
     {
         $results = [];
 
-        $finishedTasksAtomic = new Atomic();
-        $waitingAtomic = new Atomic();
-
-        $scheduledTasksTotal = count($this->queue);
         $workerProcesses = [];
 
         $currentCpu = 0;
 
         while (($queueItem = array_shift($this->queue))) {
             $workerProcess = new Process(
-                callback: function (Process $worker) use ($finishedTasksAtomic, $queueItem, $scheduledTasksTotal, $waitingAtomic) {
-                    try {
-                        $worker->exportSocket()->send(igbinary_serialize($queueItem()));
-                    } finally {
-                        $finishedTasksAtomic->add(1);
-
-                        if ($scheduledTasksTotal <= $finishedTasksAtomic->get()) {
-                            $waitingAtomic->wakeup();
-                        }
-                    }
+                callback: function (Process $worker) use ($queueItem) {
+                    $worker->exportSocket()->send(igbinary_serialize($queueItem()));
                 },
                 enable_coroutine: true,
                 pipe_type: 1,
@@ -121,8 +103,6 @@ public function process() : array
             $currentCpu = ($currentCpu + 1) % $this->cpus;
         }
 
-        $waitingAtomic->wait(-1);
-
         run(function () use (&$results, $workerProcesses) {
             foreach ($workerProcesses as $workerProcess) {
                 $receivedData = $workerProcess->exportSocket()->recv();

From f2d829a313a1d32df3ef27c3f33319a08324a269 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Fri, 12 Jan 2024 16:46:46 +0100
Subject: [PATCH 14/18] chore(swoole): php backwards compatibility

---
 src/Backends/Swoole.php | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 0c27bcb94..358e3a17e 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -84,17 +84,18 @@ public function process() : array
 
         while (($queueItem = array_shift($this->queue))) {
             $workerProcess = new Process(
-                callback: function (Process $worker) use ($queueItem) {
+                function (Process $worker) use ($queueItem) {
                     $worker->exportSocket()->send(igbinary_serialize($queueItem()));
                 },
-                enable_coroutine: true,
-                pipe_type: 1,
-                redirect_stdin_and_stdout: false,
+                // redirect_stdin_and_stdout
+                false,
+                // pipe_type
+                SOCK_STREAM,
+                // enable_coroutine
+                true,
             );
 
-            $workerProcess->setAffinity([
-                $currentCpu,
-            ]);
+            $workerProcess->setAffinity([$currentCpu]);
             $workerProcess->setBlocking(false);
             $workerProcess->start();
 

From cfd31fb2e68225bf4217e3bda67f28c35a0233c4 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 15 Jan 2024 20:25:49 +0100
Subject: [PATCH 15/18] fix: phpstan, socket message size

---
 benchmarks/Classifiers/OneVsRestBench.php     | 10 ++-
 benchmarks/Classifiers/RandomForestBench.php  | 42 +++++----
 phpunit.xml                                   |  2 +-
 src/Backends/Swoole.php                       | 85 ++++++++++++------
 src/Classifiers/LogisticRegression.php        | 16 ++++
 src/Serializers/Igbinary.php                  | 87 -------------------
 tests/Backends/SwooleTest.php                 |  2 +-
 tests/Classifiers/OneVsRestTest.php           | 18 ++--
 tests/DataProvider/BackendProviderTrait.php   | 32 ++++---
 .../{SQTableTest.php => SQLTableTest.php}     |  0
 tests/Transformers/ImageRotatorTest.php       |  2 +-
 11 files changed, 143 insertions(+), 153 deletions(-)
 delete mode 100644 src/Serializers/Igbinary.php
 rename tests/Extractors/{SQTableTest.php => SQLTableTest.php} (100%)

diff --git a/benchmarks/Classifiers/OneVsRestBench.php b/benchmarks/Classifiers/OneVsRestBench.php
index 2bb8bc319..86fb1de06 100644
--- a/benchmarks/Classifiers/OneVsRestBench.php
+++ b/benchmarks/Classifiers/OneVsRestBench.php
@@ -2,11 +2,13 @@
 
 namespace Rubix\ML\Benchmarks\Classifiers;
 
+use Rubix\ML\Backends\Backend;
 use Rubix\ML\Classifiers\OneVsRest;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\Classifiers\LogisticRegression;
 use Rubix\ML\NeuralNet\Optimizers\Stochastic;
 use Rubix\ML\Datasets\Generators\Agglomerate;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 
 /**
  * @Groups({"Classifiers"})
@@ -14,6 +16,8 @@
  */
 class OneVsRestBench
 {
+    use BackendProviderTrait;
+
     protected const TRAINING_SIZE = 10000;
 
     protected const TESTING_SIZE = 10000;
@@ -52,9 +56,13 @@ public function setUp() : void
      * @Subject
      * @Iterations(5)
      * @OutputTimeUnit("seconds", precision=3)
+     * @ParamProviders("provideBackends")
+     * @param array{ backend: Backend } $params
      */
-    public function trainPredict() : void
+    public function trainPredict(array $params) : void
     {
+        $this->estimator->setBackend($params['backend']);
+
         $this->estimator->train($this->training);
 
         $this->estimator->predict($this->testing);
diff --git a/benchmarks/Classifiers/RandomForestBench.php b/benchmarks/Classifiers/RandomForestBench.php
index c1b02b817..95713bfe2 100644
--- a/benchmarks/Classifiers/RandomForestBench.php
+++ b/benchmarks/Classifiers/RandomForestBench.php
@@ -2,12 +2,12 @@
 
 namespace Rubix\ML\Benchmarks\Classifiers;
 
-use Rubix\ML\Backends\Amp;
-use Rubix\ML\Backends\Swoole as SwooleBackend;
+use Rubix\ML\Backends\Backend;
 use Rubix\ML\Classifiers\RandomForest;
 use Rubix\ML\Datasets\Generators\Blob;
 use Rubix\ML\Classifiers\ClassificationTree;
 use Rubix\ML\Datasets\Generators\Agglomerate;
+use Rubix\ML\Tests\DataProvider\BackendProviderTrait;
 use Rubix\ML\Transformers\IntervalDiscretizer;
 
 /**
@@ -15,6 +15,8 @@
  */
 class RandomForestBench
 {
+    use BackendProviderTrait;
+
     protected const TRAINING_SIZE = 10000;
 
     protected const TESTING_SIZE = 10000;
@@ -47,8 +49,6 @@ public function setUpContinuous() : void
         $this->testing = $generator->generate(self::TESTING_SIZE);
 
         $this->estimator = new RandomForest(new ClassificationTree(30));
-        $this->estimator->setBackend(new SwooleBackend());
-        // $this->estimator->setBackend(new Amp());
     }
 
     public function setUpCategorical() : void
@@ -74,24 +74,32 @@ public function setUpCategorical() : void
      * @Iterations(5)
      * @BeforeMethods({"setUpContinuous"})
      * @OutputTimeUnit("seconds", precision=3)
+     * @ParamProviders("provideBackends")
+     * @param array{ backend: Backend } $params
      */
-    public function continuous() : void
+    public function continuous(array $params) : void
     {
+        $this->estimator->setBackend($params['backend']);
+
         $this->estimator->train($this->training);
 
         $this->estimator->predict($this->testing);
     }
 
-    // /**
-    //  * @Subject
-    //  * @Iterations(5)
-    //  * @BeforeMethods({"setUpCategorical"})
-    //  * @OutputTimeUnit("seconds", precision=3)
-    //  */
-    // public function categorical() : void
-    // {
-    //     $this->estimator->train($this->training);
-
-    //     $this->estimator->predict($this->testing);
-    // }
+    /**
+     * @Subject
+     * @Iterations(5)
+     * @BeforeMethods({"setUpCategorical"})
+     * @OutputTimeUnit("seconds", precision=3)
+     * @ParamProviders("provideBackends")
+     * @param array{ backend: Backend } $params
+     */
+    public function categorical(array $params) : void
+    {
+        $this->estimator->setBackend($params['backend']);
+
+        $this->estimator->train($this->training);
+
+        $this->estimator->predict($this->testing);
+    }
 }
diff --git a/phpunit.xml b/phpunit.xml
index 54289bc72..f2656a836 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -9,7 +9,7 @@
   convertNoticesToExceptions="true"
   convertWarningsToExceptions="true"
   forceCoversAnnotation="true"
-  processIsolation="false"
+  processIsolation="true"
   stopOnFailure="false"
   xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
 >
diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 358e3a17e..65a5ca56a 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -3,10 +3,10 @@
 namespace Rubix\ML\Backends;
 
 use Rubix\ML\Backends\Tasks\Task;
-use Rubix\ML\Serializers\Serializer;
-use Rubix\ML\Serializers\Igbinary;
-use Rubix\ML\Serializers\Native;
 use Rubix\ML\Specifications\ExtensionIsLoaded;
+use Rubix\ML\Specifications\SwooleExtensionIsLoaded;
+use RuntimeException;
+use Swoole\Atomic;
 use Swoole\Process;
 
 use function Swoole\Coroutine\run;
@@ -28,21 +28,14 @@ class Swoole implements Backend
 
     private int $cpus;
 
-    private Serializer $serializer;
+    private int $hasIgbinary;
 
-    public function __construct(?Serializer $serializer = null)
+    public function __construct()
     {
-        $this->cpus = swoole_cpu_num();
+        SwooleExtensionIsLoaded::create()->check();
 
-        if ($serializer) {
-            $this->serializer = $serializer;
-        } else {
-            if (ExtensionIsLoaded::with('igbinary')->passes()) {
-                $this->serializer = new Igbinary();
-            } else {
-                $this->serializer = new Native();
-            }
-        }
+        $this->cpus = swoole_cpu_num();
+        $this->hasIgbinary = ExtensionIsLoaded::with('igbinary')->passes();
     }
 
     /**
@@ -78,19 +71,29 @@ public function process() : array
     {
         $results = [];
 
+        $maxMessageLength = new Atomic(0);
         $workerProcesses = [];
 
         $currentCpu = 0;
 
-        while (($queueItem = array_shift($this->queue))) {
+        foreach ($this->queue as $index => $queueItem) {
             $workerProcess = new Process(
-                function (Process $worker) use ($queueItem) {
-                    $worker->exportSocket()->send(igbinary_serialize($queueItem()));
+                function (Process $worker) use ($maxMessageLength, $queueItem) {
+                    $serialized = $this->serialize($queueItem());
+
+                    $serializedLength = strlen($serialized);
+                    $currentMaxSerializedLength = $maxMessageLength->get();
+
+                    if ($serializedLength > $currentMaxSerializedLength) {
+                        $maxMessageLength->set($serializedLength);
+                    }
+
+                    $worker->exportSocket()->send($serialized);
                 },
                 // redirect_stdin_and_stdout
                 false,
                 // pipe_type
-                SOCK_STREAM,
+                SOCK_DGRAM,
                 // enable_coroutine
                 true,
             );
@@ -99,15 +102,29 @@ function (Process $worker) use ($queueItem) {
             $workerProcess->setBlocking(false);
             $workerProcess->start();
 
-            $workerProcesses[] = $workerProcess;
+            $workerProcesses[$index] = $workerProcess;
 
             $currentCpu = ($currentCpu + 1) % $this->cpus;
         }
 
-        run(function () use (&$results, $workerProcesses) {
-            foreach ($workerProcesses as $workerProcess) {
-                $receivedData = $workerProcess->exportSocket()->recv();
-                $unserialized = igbinary_unserialize($receivedData);
+        run(function () use ($maxMessageLength, &$results, $workerProcesses) {
+            foreach ($workerProcesses as $index => $workerProcess) {
+                $status = $workerProcess->wait();
+
+                if (0 !== $status['code']) {
+                    throw new RuntimeException('Worker process exited with an error');
+                }
+
+                $socket = $workerProcess->exportSocket();
+
+                if ($socket->isClosed()) {
+                    throw new RuntimeException('Coroutine socket is closed');
+                }
+
+                $maxMessageLengthValue = $maxMessageLength->get();
+
+                $receivedData = $socket->recv($maxMessageLengthValue);
+                $unserialized = $this->unserialize($receivedData);
 
                 $results[] = $unserialized;
             }
@@ -124,6 +141,24 @@ public function flush() : void
         $this->queue = [];
     }
 
+    private function serialize(mixed $data) : string
+    {
+        if ($this->hasIgbinary) {
+            return igbinary_serialize($data);
+        }
+
+        return serialize($data);
+    }
+
+    private function unserialize(string $serialized) : mixed
+    {
+        if ($this->hasIgbinary) {
+            return igbinary_unserialize($serialized);
+        }
+
+        return unserialize($serialized);
+    }
+
     /**
      * Return the string representation of the object.
      *
@@ -133,6 +168,6 @@ public function flush() : void
      */
     public function __toString() : string
     {
-        return 'Swoole\\Process';
+        return 'Swoole';
     }
 }
diff --git a/src/Classifiers/LogisticRegression.php b/src/Classifiers/LogisticRegression.php
index 1626fbb57..d0cac23a8 100644
--- a/src/Classifiers/LogisticRegression.php
+++ b/src/Classifiers/LogisticRegression.php
@@ -491,4 +491,20 @@ public function __toString() : string
     {
         return 'Logistic Regression (' . Params::stringify($this->params()) . ')';
     }
+
+    /**
+     * Without this method, causes errors with Swoole backend + Igbinary
+     * serialization.
+     *
+     * Can be removed if it's no longer the case.
+     *
+     * @internal
+     * @param array<string,mixed> $data
+     */
+    public function __unserialize(array $data) : void
+    {
+        foreach ($data as $propertyName => $propertyValue) {
+            $this->{$propertyName} = $propertyValue;
+        }
+    }
 }
diff --git a/src/Serializers/Igbinary.php b/src/Serializers/Igbinary.php
deleted file mode 100644
index 2c18ec348..000000000
--- a/src/Serializers/Igbinary.php
+++ /dev/null
@@ -1,87 +0,0 @@
-<?php
-
-namespace Rubix\ML\Serializers;
-
-use Rubix\ML\Encoding;
-use Rubix\ML\Persistable;
-use Rubix\ML\Exceptions\RuntimeException;
-use Rubix\ML\Specifications\ExtensionIsLoaded;
-use __PHP_Incomplete_Class;
-
-use function is_object;
-
-/**
- * Igbinary
- *
- * Igbinary is a compact binary format that serves as a drop-in replacement for the native PHP serializer.
- *
- * @category    Machine Learning
- * @package     Rubix/ML
- * @author      Andrew DalPino
- */
-class Igbinary implements Serializer
-{
-    public function __construct()
-    {
-        ExtensionIsLoaded::with('igbinary')->check();
-    }
-
-    /**
-     * Serialize a persistable object and return the data.
-     *
-     * @internal
-     *
-     * @param \Rubix\ML\Persistable $persistable
-     * @throws \Rubix\ML\Exceptions\RuntimeException
-     * @return \Rubix\ML\Encoding
-     */
-    public function serialize(Persistable $persistable) : Encoding
-    {
-        $data = igbinary_serialize($persistable);
-
-        if (!$data) {
-            throw new RuntimeException('Could not serialize data.');
-        }
-
-        return new Encoding($data);
-    }
-
-    /**
-     * Deserialize a persistable object and return it.
-     *
-     * @internal
-     *
-     * @param \Rubix\ML\Encoding $encoding
-     * @throws \Rubix\ML\Exceptions\RuntimeException
-     * @return \Rubix\ML\Persistable
-     */
-    public function deserialize(Encoding $encoding) : Persistable
-    {
-        $persistable = igbinary_unserialize($encoding);
-
-        if (!is_object($persistable)) {
-            throw new RuntimeException('deserialized data must be an object.');
-        }
-
-        if ($persistable instanceof __PHP_Incomplete_Class) {
-            throw new RuntimeException('Missing class for object data.');
-        }
-
-        if (!$persistable instanceof Persistable) {
-            throw new RuntimeException('deserialized object must'
-                . ' implement the Persistable interface.');
-        }
-
-        return $persistable;
-    }
-
-    /**
-     * Return the string representation of the object.
-     *
-     * @return string
-     */
-    public function __toString() : string
-    {
-        return 'Igbinary';
-    }
-}
diff --git a/tests/Backends/SwooleTest.php b/tests/Backends/SwooleTest.php
index ece9e41a6..60cbf526f 100644
--- a/tests/Backends/SwooleTest.php
+++ b/tests/Backends/SwooleTest.php
@@ -17,7 +17,7 @@
 class SwooleTest extends TestCase
 {
     /**
-     * @var \Rubix\ML\Backends\Swoole\Process
+     * @var \Rubix\ML\Backends\Swoole
      */
     protected $backend;
 
diff --git a/tests/Classifiers/OneVsRestTest.php b/tests/Classifiers/OneVsRestTest.php
index 9b3353218..f52b5066b 100644
--- a/tests/Classifiers/OneVsRestTest.php
+++ b/tests/Classifiers/OneVsRestTest.php
@@ -162,13 +162,13 @@ public function trainPredictProba(Backend $backend) : void
         $this->assertGreaterThanOrEqual(self::MIN_SCORE, $score);
     }
 
-    /**
-     * @test
-     */
-    public function predictUntrained() : void
-    {
-        $this->expectException(RuntimeException::class);
-
-        $this->estimator->predict(Unlabeled::quick());
-    }
+    // /**
+    //  * @test
+    //  */
+    // public function predictUntrained() : void
+    // {
+    //     $this->expectException(RuntimeException::class);
+
+    //     $this->estimator->predict(Unlabeled::quick());
+    // }
 }
diff --git a/tests/DataProvider/BackendProviderTrait.php b/tests/DataProvider/BackendProviderTrait.php
index f33d72a6a..08851742f 100644
--- a/tests/DataProvider/BackendProviderTrait.php
+++ b/tests/DataProvider/BackendProviderTrait.php
@@ -2,32 +2,42 @@
 
 namespace Rubix\ML\Tests\DataProvider;
 
+use Generator;
 use Rubix\ML\Backends\Backend;
 use Rubix\ML\Backends\Serial;
 use Rubix\ML\Backends\Amp;
 use Rubix\ML\Backends\Swoole;
+use Rubix\ML\Specifications\ExtensionIsLoaded;
 use Rubix\ML\Specifications\SwooleExtensionIsLoaded;
 
 trait BackendProviderTrait
 {
     /**
-     * @return array<Backend>
+     * @return Generator<string,array<Backend>>
      */
-    public static function provideBackends() : array
+    public static function provideBackends() : Generator
     {
-        $backends = [];
-
         $serialBackend = new Serial();
-        $backends[(string) $serialBackend] = [$serialBackend];
 
-        $ampBackend = new Amp();
-        $backends[(string) $ampBackend] = [$ampBackend];
+        yield (string) $serialBackend => [
+            'backend' => $serialBackend,
+        ];
+
+        // $ampBackend = new Amp();
+
+        // yield (string) $ampBackend => [
+        //     'backend' => $ampBackend,
+        // ];
 
-        if (SwooleExtensionIsLoaded::create()->passes()) {
+        if (
+            SwooleExtensionIsLoaded::create()->passes()
+            && ExtensionIsLoaded::with('igbinary')->passes()
+        ) {
             $swooleProcessBackend = new Swoole();
-            $backends[(string) $swooleProcessBackend] = [$swooleProcessBackend];
-        }
 
-        return $backends;
+            yield (string) $swooleProcessBackend => [
+                'backend' => $swooleProcessBackend,
+            ];
+        }
     }
 }
diff --git a/tests/Extractors/SQTableTest.php b/tests/Extractors/SQLTableTest.php
similarity index 100%
rename from tests/Extractors/SQTableTest.php
rename to tests/Extractors/SQLTableTest.php
diff --git a/tests/Transformers/ImageRotatorTest.php b/tests/Transformers/ImageRotatorTest.php
index ef63b5d68..2ea9004ac 100644
--- a/tests/Transformers/ImageRotatorTest.php
+++ b/tests/Transformers/ImageRotatorTest.php
@@ -12,7 +12,7 @@
  * @requires extension gd
  * @covers \Rubix\ML\Transformers\ImageRotator
  */
-class RandomizedImageRotatorTest extends TestCase
+class ImageRotatorTest extends TestCase
 {
     /**
      * @var \Rubix\ML\Transformers\ImageRotator

From 703404b979215273cfca2de6f67da735a6883ed7 Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Mon, 15 Jan 2024 20:27:25 +0100
Subject: [PATCH 16/18] fix: uncomment test

---
 tests/Classifiers/OneVsRestTest.php | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tests/Classifiers/OneVsRestTest.php b/tests/Classifiers/OneVsRestTest.php
index f52b5066b..9b3353218 100644
--- a/tests/Classifiers/OneVsRestTest.php
+++ b/tests/Classifiers/OneVsRestTest.php
@@ -162,13 +162,13 @@ public function trainPredictProba(Backend $backend) : void
         $this->assertGreaterThanOrEqual(self::MIN_SCORE, $score);
     }
 
-    // /**
-    //  * @test
-    //  */
-    // public function predictUntrained() : void
-    // {
-    //     $this->expectException(RuntimeException::class);
-
-    //     $this->estimator->predict(Unlabeled::quick());
-    // }
+    /**
+     * @test
+     */
+    public function predictUntrained() : void
+    {
+        $this->expectException(RuntimeException::class);
+
+        $this->estimator->predict(Unlabeled::quick());
+    }
 }

From cb1ee71360ba19c85b7e0509bd85204f39977dff Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Wed, 24 Jan 2024 19:44:59 +0100
Subject: [PATCH 17/18] style: composer fix

---
 src/AnomalyDetectors/LocalOutlierFactor.php            |  2 +-
 src/AnomalyDetectors/Loda.php                          |  2 +-
 src/AnomalyDetectors/OneClassSVM.php                   |  4 ++--
 src/Backends/Swoole.php                                |  2 +-
 src/BootstrapAggregator.php                            |  2 +-
 src/Classifiers/AdaBoost.php                           |  2 +-
 src/Classifiers/KDNeighbors.php                        |  2 +-
 src/Classifiers/KNearestNeighbors.php                  |  2 +-
 src/Classifiers/LogisticRegression.php                 |  6 +++---
 src/Classifiers/LogitBoost.php                         |  4 ++--
 src/Classifiers/MultilayerPerceptron.php               |  8 ++++----
 src/Classifiers/OneVsRest.php                          |  2 +-
 src/Classifiers/RadiusNeighbors.php                    |  2 +-
 src/Classifiers/RandomForest.php                       |  2 +-
 src/Classifiers/SoftmaxClassifier.php                  |  6 +++---
 src/Clusterers/DBSCAN.php                              |  2 +-
 src/Clusterers/FuzzyCMeans.php                         |  4 ++--
 src/Clusterers/GaussianMixture.php                     |  2 +-
 src/Clusterers/KMeans.php                              |  4 ++--
 src/Clusterers/MeanShift.php                           |  4 ++--
 src/Clusterers/Seeders/KMC2.php                        |  2 +-
 src/Clusterers/Seeders/PlusPlus.php                    |  2 +-
 src/Datasets/Generators/Blob.php                       |  2 +-
 src/Datasets/Generators/Circle.php                     |  2 +-
 src/Datasets/Generators/HalfMoon.php                   |  2 +-
 src/Datasets/Generators/Hyperplane.php                 |  2 +-
 src/Datasets/Generators/SwissRoll.php                  |  2 +-
 src/Extractors/SQLTable.php                            |  2 +-
 src/Graph/Nodes/Clique.php                             |  2 +-
 src/Graph/Nodes/Neighborhood.php                       |  2 +-
 src/Graph/Nodes/Traits/HasBinaryChildrenTrait.php      |  4 ++--
 src/Graph/Trees/BallTree.php                           |  4 ++--
 src/Graph/Trees/DecisionTree.php                       |  2 +-
 src/Graph/Trees/ITree.php                              |  2 +-
 src/Graph/Trees/KDTree.php                             |  4 ++--
 src/GridSearch.php                                     |  6 +++---
 src/NeuralNet/FeedForward.php                          |  6 +++---
 src/NeuralNet/Layers/Activation.php                    |  6 +++---
 src/NeuralNet/Layers/BatchNorm.php                     | 10 +++++-----
 src/NeuralNet/Layers/Binary.php                        |  8 ++++----
 src/NeuralNet/Layers/Continuous.php                    |  4 ++--
 src/NeuralNet/Layers/Dense.php                         | 10 +++++-----
 src/NeuralNet/Layers/Dropout.php                       |  2 +-
 src/NeuralNet/Layers/Multiclass.php                    |  8 ++++----
 src/NeuralNet/Layers/PReLU.php                         |  6 +++---
 src/NeuralNet/Layers/Swish.php                         | 10 +++++-----
 src/NeuralNet/Parameter.php                            |  2 +-
 src/PersistentModel.php                                |  6 +++---
 src/Pipeline.php                                       |  2 +-
 src/Regressors/Adaline.php                             |  6 +++---
 src/Regressors/GradientBoost.php                       |  4 ++--
 src/Regressors/KDNeighborsRegressor.php                |  2 +-
 src/Regressors/KNNRegressor.php                        |  2 +-
 src/Regressors/MLPRegressor.php                        |  8 ++++----
 src/Regressors/RadiusNeighborsRegressor.php            |  2 +-
 src/Regressors/Ridge.php                               |  2 +-
 src/Regressors/SVR.php                                 |  4 ++--
 src/Serializers/GzipNative.php                         |  2 +-
 src/Serializers/RBX.php                                |  2 +-
 src/Specifications/DatasetHasDimensionality.php        |  2 +-
 src/Specifications/DatasetIsLabeled.php                |  2 +-
 src/Specifications/DatasetIsNotEmpty.php               |  2 +-
 src/Specifications/EstimatorIsCompatibleWithMetric.php |  4 ++--
 src/Specifications/LabelsAreCompatibleWithLearner.php  |  4 ++--
 .../SamplesAreCompatibleWithDistance.php               |  4 ++--
 .../SamplesAreCompatibleWithEstimator.php              |  4 ++--
 .../SamplesAreCompatibleWithTransformer.php            |  4 ++--
 src/Specifications/SwooleExtensionIsLoaded.php         |  2 +-
 src/Tokenizers/KSkipNGram.php                          |  4 ++--
 src/Tokenizers/NGram.php                               |  4 ++--
 src/Traits/LoggerAware.php                             |  2 +-
 src/Traits/Multiprocessing.php                         |  2 +-
 src/Transformers/GaussianRandomProjector.php           |  2 +-
 src/Transformers/HotDeckImputer.php                    |  2 +-
 src/Transformers/KNNImputer.php                        |  2 +-
 src/Transformers/LinearDiscriminantAnalysis.php        |  2 +-
 src/Transformers/MissingDataImputer.php                |  4 ++--
 src/Transformers/PrincipalComponentAnalysis.php        |  2 +-
 src/Transformers/TSNE.php                              |  2 +-
 src/Transformers/TokenHashingVectorizer.php            |  2 +-
 src/Transformers/TruncatedSVD.php                      |  2 +-
 src/Transformers/WordCountVectorizer.php               |  2 +-
 tests/Backends/SwooleTest.php                          |  2 +-
 tests/Graph/Nodes/NeighborhoodTest.php                 |  2 +-
 tests/NeuralNet/ParameterTest.php                      |  2 +-
 tests/Transformers/ImageRotatorTest.php                |  2 +-
 86 files changed, 145 insertions(+), 145 deletions(-)

diff --git a/src/AnomalyDetectors/LocalOutlierFactor.php b/src/AnomalyDetectors/LocalOutlierFactor.php
index 4ebda0f00..5c798b4b6 100644
--- a/src/AnomalyDetectors/LocalOutlierFactor.php
+++ b/src/AnomalyDetectors/LocalOutlierFactor.php
@@ -67,7 +67,7 @@ class LocalOutlierFactor implements Estimator, Learner, Scoring, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The precomputed k distances between each training sample and its k'th nearest neighbor.
diff --git a/src/AnomalyDetectors/Loda.php b/src/AnomalyDetectors/Loda.php
index f06b9a4a7..cf76762e3 100644
--- a/src/AnomalyDetectors/Loda.php
+++ b/src/AnomalyDetectors/Loda.php
@@ -100,7 +100,7 @@ class Loda implements Estimator, Learner, Online, Scoring, Persistable
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $r = null;
+    protected ?Matrix $r = null;
 
     /**
      * The edges and bin counts of each histogram.
diff --git a/src/AnomalyDetectors/OneClassSVM.php b/src/AnomalyDetectors/OneClassSVM.php
index faf1111be..10969ab6f 100644
--- a/src/AnomalyDetectors/OneClassSVM.php
+++ b/src/AnomalyDetectors/OneClassSVM.php
@@ -44,7 +44,7 @@ class OneClassSVM implements Estimator, Learner
      *
      * @var svm
      */
-    protected \svm $svm;
+    protected svm $svm;
 
     /**
      * The hyper-parameters of the model.
@@ -58,7 +58,7 @@ class OneClassSVM implements Estimator, Learner
      *
      * @var \svmmodel|null
      */
-    protected ?\svmmodel $model = null;
+    protected ?svmmodel $model = null;
 
     /**
      * @param float $nu
diff --git a/src/Backends/Swoole.php b/src/Backends/Swoole.php
index 65a5ca56a..34eb894b8 100644
--- a/src/Backends/Swoole.php
+++ b/src/Backends/Swoole.php
@@ -43,7 +43,7 @@ public function __construct()
      *
      * @internal
      *
-     * @param \Rubix\ML\Backends\Tasks\Task $task
+     * @param Task $task
      * @param callable(mixed,mixed):void $after
      * @param mixed $context
      */
diff --git a/src/BootstrapAggregator.php b/src/BootstrapAggregator.php
index 742dcc6ab..fc30cc882 100644
--- a/src/BootstrapAggregator.php
+++ b/src/BootstrapAggregator.php
@@ -64,7 +64,7 @@ class BootstrapAggregator implements Estimator, Learner, Parallel, Persistable
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * The number of base learners to train in the ensemble.
diff --git a/src/Classifiers/AdaBoost.php b/src/Classifiers/AdaBoost.php
index 4f428c5f4..9c74fbd7a 100644
--- a/src/Classifiers/AdaBoost.php
+++ b/src/Classifiers/AdaBoost.php
@@ -72,7 +72,7 @@ class AdaBoost implements Estimator, Learner, Probabilistic, Verbose, Persistabl
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * The learning rate of the ensemble i.e. the *shrinkage* applied to each step.
diff --git a/src/Classifiers/KDNeighbors.php b/src/Classifiers/KDNeighbors.php
index 642b64e16..4ef9f5864 100644
--- a/src/Classifiers/KDNeighbors.php
+++ b/src/Classifiers/KDNeighbors.php
@@ -60,7 +60,7 @@ class KDNeighbors implements Estimator, Learner, Probabilistic, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The zero vector for the possible class outcomes.
diff --git a/src/Classifiers/KNearestNeighbors.php b/src/Classifiers/KNearestNeighbors.php
index d5293c932..ee5c4b39b 100644
--- a/src/Classifiers/KNearestNeighbors.php
+++ b/src/Classifiers/KNearestNeighbors.php
@@ -62,7 +62,7 @@ class KNearestNeighbors implements Estimator, Learner, Online, Probabilistic, Pe
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The zero vector for the possible class outcomes.
diff --git a/src/Classifiers/LogisticRegression.php b/src/Classifiers/LogisticRegression.php
index ffa291a84..81eef3ac3 100644
--- a/src/Classifiers/LogisticRegression.php
+++ b/src/Classifiers/LogisticRegression.php
@@ -67,7 +67,7 @@ class LogisticRegression implements Estimator, Learner, Online, Probabilistic, R
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * The amount of L2 regularization applied to the weights of the output layer.
@@ -103,14 +103,14 @@ class LogisticRegression implements Estimator, Learner, Online, Probabilistic, R
      *
      * @var ClassificationLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\ClassificationLoss $costFn;
+    protected ClassificationLoss $costFn;
 
     /**
      * The underlying neural network instance.
      *
      * @var \Rubix\ML\NeuralNet\FeedForward|null
      */
-    protected ?\Rubix\ML\NeuralNet\FeedForward $network = null;
+    protected ?FeedForward $network = null;
 
     /**
      * The unique class labels.
diff --git a/src/Classifiers/LogitBoost.php b/src/Classifiers/LogitBoost.php
index 071dfed39..f12588cfb 100644
--- a/src/Classifiers/LogitBoost.php
+++ b/src/Classifiers/LogitBoost.php
@@ -89,7 +89,7 @@ class LogitBoost implements Estimator, Learner, Probabilistic, RanksFeatures, Ve
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $booster;
+    protected Learner $booster;
 
     /**
      * The learning rate of the ensemble i.e. the *shrinkage* applied to each step.
@@ -138,7 +138,7 @@ class LogitBoost implements Estimator, Learner, Probabilistic, RanksFeatures, Ve
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * The ensemble of boosters.
diff --git a/src/Classifiers/MultilayerPerceptron.php b/src/Classifiers/MultilayerPerceptron.php
index 1018d10c4..233c8b1eb 100644
--- a/src/Classifiers/MultilayerPerceptron.php
+++ b/src/Classifiers/MultilayerPerceptron.php
@@ -85,7 +85,7 @@ class MultilayerPerceptron implements Estimator, Learner, Online, Probabilistic,
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * The amount of L2 regularization applied to the weights of the output layer.
@@ -127,21 +127,21 @@ class MultilayerPerceptron implements Estimator, Learner, Online, Probabilistic,
      *
      * @var ClassificationLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\ClassificationLoss $costFn;
+    protected ClassificationLoss $costFn;
 
     /**
      * The validation metric used to score the generalization performance of the model during training.
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * The underlying neural network instance.
      *
      * @var \Rubix\ML\NeuralNet\FeedForward|null
      */
-    protected ?\Rubix\ML\NeuralNet\FeedForward $network = null;
+    protected ?FeedForward $network = null;
 
     /**
      * The unique class labels.
diff --git a/src/Classifiers/OneVsRest.php b/src/Classifiers/OneVsRest.php
index 7c07e2627..841fb2751 100644
--- a/src/Classifiers/OneVsRest.php
+++ b/src/Classifiers/OneVsRest.php
@@ -51,7 +51,7 @@ class OneVsRest implements Estimator, Learner, Probabilistic, Parallel, Persista
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * A map of each class to its binary classifier.
diff --git a/src/Classifiers/RadiusNeighbors.php b/src/Classifiers/RadiusNeighbors.php
index b1e3544c9..1dc670186 100644
--- a/src/Classifiers/RadiusNeighbors.php
+++ b/src/Classifiers/RadiusNeighbors.php
@@ -60,7 +60,7 @@ class RadiusNeighbors implements Estimator, Learner, Probabilistic, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The class label for any samples that have 0 neighbors within the specified radius.
diff --git a/src/Classifiers/RandomForest.php b/src/Classifiers/RandomForest.php
index 5d2b8d5cb..eb62f5e32 100644
--- a/src/Classifiers/RandomForest.php
+++ b/src/Classifiers/RandomForest.php
@@ -73,7 +73,7 @@ class RandomForest implements Estimator, Learner, Probabilistic, Parallel, Ranks
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * The number of learners to train in the ensemble.
diff --git a/src/Classifiers/SoftmaxClassifier.php b/src/Classifiers/SoftmaxClassifier.php
index 998035701..3038c04a3 100644
--- a/src/Classifiers/SoftmaxClassifier.php
+++ b/src/Classifiers/SoftmaxClassifier.php
@@ -64,7 +64,7 @@ class SoftmaxClassifier implements Estimator, Learner, Online, Probabilistic, Ve
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * The amount of L2 regularization applied to the weights of the output layer.
@@ -99,14 +99,14 @@ class SoftmaxClassifier implements Estimator, Learner, Online, Probabilistic, Ve
      *
      * @var ClassificationLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\ClassificationLoss $costFn;
+    protected ClassificationLoss $costFn;
 
     /**
      * The underlying neural network instance.
      *
      * @var \Rubix\ML\NeuralNet\FeedForward|null
      */
-    protected ?\Rubix\ML\NeuralNet\FeedForward $network = null;
+    protected ?FeedForward $network = null;
 
     /**
      * The unique class labels.
diff --git a/src/Clusterers/DBSCAN.php b/src/Clusterers/DBSCAN.php
index 44112e02a..c24546d37 100644
--- a/src/Clusterers/DBSCAN.php
+++ b/src/Clusterers/DBSCAN.php
@@ -73,7 +73,7 @@ class DBSCAN implements Estimator
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * @param float $radius
diff --git a/src/Clusterers/FuzzyCMeans.php b/src/Clusterers/FuzzyCMeans.php
index 49d5716ff..dd3b27b84 100644
--- a/src/Clusterers/FuzzyCMeans.php
+++ b/src/Clusterers/FuzzyCMeans.php
@@ -92,14 +92,14 @@ class FuzzyCMeans implements Estimator, Learner, Probabilistic, Verbose, Persist
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The cluster centroid seeder.
      *
      * @var Seeder
      */
-    protected \Rubix\ML\Clusterers\Seeders\Seeder $seeder;
+    protected Seeder $seeder;
 
     /**
      * The computed centroid vectors of the training data.
diff --git a/src/Clusterers/GaussianMixture.php b/src/Clusterers/GaussianMixture.php
index 4445d0422..68338cfd9 100644
--- a/src/Clusterers/GaussianMixture.php
+++ b/src/Clusterers/GaussianMixture.php
@@ -97,7 +97,7 @@ class GaussianMixture implements Estimator, Learner, Probabilistic, Verbose, Per
      *
      * @var Seeder
      */
-    protected \Rubix\ML\Clusterers\Seeders\Seeder $seeder;
+    protected Seeder $seeder;
 
     /**
      * The precomputed log prior probabilities of each cluster.
diff --git a/src/Clusterers/KMeans.php b/src/Clusterers/KMeans.php
index 852b178c4..280e70922 100644
--- a/src/Clusterers/KMeans.php
+++ b/src/Clusterers/KMeans.php
@@ -96,14 +96,14 @@ class KMeans implements Estimator, Learner, Online, Probabilistic, Verbose, Pers
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The cluster centroid seeder.
      *
      * @var Seeder
      */
-    protected \Rubix\ML\Clusterers\Seeders\Seeder $seeder;
+    protected Seeder $seeder;
 
     /**
      * The computed centroid vectors of the training data.
diff --git a/src/Clusterers/MeanShift.php b/src/Clusterers/MeanShift.php
index 0d89ce00f..97af51353 100644
--- a/src/Clusterers/MeanShift.php
+++ b/src/Clusterers/MeanShift.php
@@ -104,14 +104,14 @@ class MeanShift implements Estimator, Learner, Probabilistic, Verbose, Persistab
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The cluster centroid seeder.
      *
      * @var Seeder
      */
-    protected \Rubix\ML\Clusterers\Seeders\Seeder $seeder;
+    protected Seeder $seeder;
 
     /**
      * The computed centroid vectors of the training data.
diff --git a/src/Clusterers/Seeders/KMC2.php b/src/Clusterers/Seeders/KMC2.php
index d4e155e5e..717a29426 100644
--- a/src/Clusterers/Seeders/KMC2.php
+++ b/src/Clusterers/Seeders/KMC2.php
@@ -39,7 +39,7 @@ class KMC2 implements Seeder
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * @param int $m
diff --git a/src/Clusterers/Seeders/PlusPlus.php b/src/Clusterers/Seeders/PlusPlus.php
index ad4f82e24..4a59d98b4 100644
--- a/src/Clusterers/Seeders/PlusPlus.php
+++ b/src/Clusterers/Seeders/PlusPlus.php
@@ -32,7 +32,7 @@ class PlusPlus implements Seeder
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * @param \Rubix\ML\Kernels\Distance\Distance|null $kernel
diff --git a/src/Datasets/Generators/Blob.php b/src/Datasets/Generators/Blob.php
index 994d6fa52..62f703ae6 100644
--- a/src/Datasets/Generators/Blob.php
+++ b/src/Datasets/Generators/Blob.php
@@ -32,7 +32,7 @@ class Blob implements Generator
      *
      * @var Vector
      */
-    protected \Tensor\Vector $center;
+    protected Vector $center;
 
     /**
      * The standard deviation of the blob.
diff --git a/src/Datasets/Generators/Circle.php b/src/Datasets/Generators/Circle.php
index d0a5ee14c..aed785d65 100644
--- a/src/Datasets/Generators/Circle.php
+++ b/src/Datasets/Generators/Circle.php
@@ -27,7 +27,7 @@ class Circle implements Generator
      *
      * @var Vector
      */
-    protected \Tensor\Vector $center;
+    protected Vector $center;
 
     /**
      * The scaling factor of the circle.
diff --git a/src/Datasets/Generators/HalfMoon.php b/src/Datasets/Generators/HalfMoon.php
index 26486240e..e41a4a265 100644
--- a/src/Datasets/Generators/HalfMoon.php
+++ b/src/Datasets/Generators/HalfMoon.php
@@ -26,7 +26,7 @@ class HalfMoon implements Generator
      *
      * @var Vector
      */
-    protected \Tensor\Vector $center;
+    protected Vector $center;
 
     /**
      * The scaling factor of the half moon.
diff --git a/src/Datasets/Generators/Hyperplane.php b/src/Datasets/Generators/Hyperplane.php
index 8afa59934..a5ae532bc 100644
--- a/src/Datasets/Generators/Hyperplane.php
+++ b/src/Datasets/Generators/Hyperplane.php
@@ -27,7 +27,7 @@ class Hyperplane implements Generator
      *
      * @var Vector
      */
-    protected \Tensor\Vector $coefficients;
+    protected Vector $coefficients;
 
     /**
      * The y intercept term.
diff --git a/src/Datasets/Generators/SwissRoll.php b/src/Datasets/Generators/SwissRoll.php
index 8cd017ffa..f0899a284 100644
--- a/src/Datasets/Generators/SwissRoll.php
+++ b/src/Datasets/Generators/SwissRoll.php
@@ -33,7 +33,7 @@ class SwissRoll implements Generator
      *
      * @var Vector
      */
-    protected \Tensor\Vector $center;
+    protected Vector $center;
 
     /**
      * The scaling factor of the swiss roll.
diff --git a/src/Extractors/SQLTable.php b/src/Extractors/SQLTable.php
index 4d2b8ed5f..50359addf 100644
--- a/src/Extractors/SQLTable.php
+++ b/src/Extractors/SQLTable.php
@@ -30,7 +30,7 @@ class SQLTable implements Extractor
      *
      * @var PDO
      */
-    protected \PDO $connection;
+    protected PDO $connection;
 
     /**
      * The name of the table to select from.
diff --git a/src/Graph/Nodes/Clique.php b/src/Graph/Nodes/Clique.php
index 8b6dedd45..169c023a0 100644
--- a/src/Graph/Nodes/Clique.php
+++ b/src/Graph/Nodes/Clique.php
@@ -26,7 +26,7 @@ class Clique implements Hypersphere, BinaryNode
      *
      * @var Labeled
      */
-    protected \Rubix\ML\Datasets\Labeled $dataset;
+    protected Labeled $dataset;
 
     /**
      * The centroid or multivariate mean of the cluster.
diff --git a/src/Graph/Nodes/Neighborhood.php b/src/Graph/Nodes/Neighborhood.php
index 9fce001f2..688f892fd 100644
--- a/src/Graph/Nodes/Neighborhood.php
+++ b/src/Graph/Nodes/Neighborhood.php
@@ -24,7 +24,7 @@ class Neighborhood implements Hypercube, BinaryNode
      *
      * @var Labeled
      */
-    protected \Rubix\ML\Datasets\Labeled $dataset;
+    protected Labeled $dataset;
 
     /**
      * The multivariate minimum of the bounding box.
diff --git a/src/Graph/Nodes/Traits/HasBinaryChildrenTrait.php b/src/Graph/Nodes/Traits/HasBinaryChildrenTrait.php
index a0c08a4c4..76aa8f484 100644
--- a/src/Graph/Nodes/Traits/HasBinaryChildrenTrait.php
+++ b/src/Graph/Nodes/Traits/HasBinaryChildrenTrait.php
@@ -23,14 +23,14 @@ trait HasBinaryChildrenTrait
      *
      * @var \Rubix\ML\Graph\Nodes\BinaryNode|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\BinaryNode $left = null;
+    protected ?BinaryNode $left = null;
 
     /**
      * The right child node.
      *
      * @var \Rubix\ML\Graph\Nodes\BinaryNode|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\BinaryNode $right = null;
+    protected ?BinaryNode $right = null;
 
     /**
      * Return the children of this node in a generator.
diff --git a/src/Graph/Trees/BallTree.php b/src/Graph/Trees/BallTree.php
index f6e02d029..8194e779a 100644
--- a/src/Graph/Trees/BallTree.php
+++ b/src/Graph/Trees/BallTree.php
@@ -47,14 +47,14 @@ class BallTree implements BinaryTree, Spatial
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The root node of the tree.
      *
      * @var \Rubix\ML\Graph\Nodes\Ball|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\Ball $root = null;
+    protected ?Ball $root = null;
 
     /**
      * @param int $maxLeafSize
diff --git a/src/Graph/Trees/DecisionTree.php b/src/Graph/Trees/DecisionTree.php
index 5c98f0e44..63be69730 100644
--- a/src/Graph/Trees/DecisionTree.php
+++ b/src/Graph/Trees/DecisionTree.php
@@ -67,7 +67,7 @@ abstract class DecisionTree implements BinaryTree, IteratorAggregate
      *
      * @var \Rubix\ML\Graph\Nodes\Split|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\Split $root = null;
+    protected ?Split $root = null;
 
     /**
      * The number of feature columns in the training set.
diff --git a/src/Graph/Trees/ITree.php b/src/Graph/Trees/ITree.php
index d44883033..23df4e8d7 100644
--- a/src/Graph/Trees/ITree.php
+++ b/src/Graph/Trees/ITree.php
@@ -43,7 +43,7 @@ class ITree implements BinaryTree
      *
      * @var \Rubix\ML\Graph\Nodes\Isolator|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\Isolator $root = null;
+    protected ?Isolator $root = null;
 
     /**
      * @param int $maxHeight
diff --git a/src/Graph/Trees/KDTree.php b/src/Graph/Trees/KDTree.php
index 20174695d..737b075be 100644
--- a/src/Graph/Trees/KDTree.php
+++ b/src/Graph/Trees/KDTree.php
@@ -46,14 +46,14 @@ class KDTree implements BinaryTree, Spatial
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The root node of the tree.
      *
      * @var \Rubix\ML\Graph\Nodes\Box|null
      */
-    protected ?\Rubix\ML\Graph\Nodes\Box $root = null;
+    protected ?Box $root = null;
 
     /**
      * @param int $maxLeafSize
diff --git a/src/GridSearch.php b/src/GridSearch.php
index 42ab7f3a3..71adcb361 100644
--- a/src/GridSearch.php
+++ b/src/GridSearch.php
@@ -62,21 +62,21 @@ class GridSearch implements Estimator, Learner, Parallel, Verbose, Persistable
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * The validator used to test the estimator.
      *
      * @var Validator
      */
-    protected \Rubix\ML\CrossValidation\Validator $validator;
+    protected Validator $validator;
 
     /**
      * The base estimator instance.
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * The validation scores obtained from the last search.
diff --git a/src/NeuralNet/FeedForward.php b/src/NeuralNet/FeedForward.php
index 957824c8c..af12139d7 100644
--- a/src/NeuralNet/FeedForward.php
+++ b/src/NeuralNet/FeedForward.php
@@ -34,7 +34,7 @@ class FeedForward implements Network
      *
      * @var Input
      */
-    protected \Rubix\ML\NeuralNet\Layers\Input $input;
+    protected Input $input;
 
     /**
      * The hidden layers of the network.
@@ -59,14 +59,14 @@ class FeedForward implements Network
      *
      * @var Output
      */
-    protected \Rubix\ML\NeuralNet\Layers\Output $output;
+    protected Output $output;
 
     /**
      * The gradient descent optimizer used to train the network.
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * @param Input $input
diff --git a/src/NeuralNet/Layers/Activation.php b/src/NeuralNet/Layers/Activation.php
index f0370f49e..29b5f37c2 100644
--- a/src/NeuralNet/Layers/Activation.php
+++ b/src/NeuralNet/Layers/Activation.php
@@ -25,7 +25,7 @@ class Activation implements Hidden
      *
      * @var ActivationFunction
      */
-    protected \Rubix\ML\NeuralNet\ActivationFunctions\ActivationFunction $activationFn;
+    protected ActivationFunction $activationFn;
 
     /**
      * The width of the layer.
@@ -39,14 +39,14 @@ class Activation implements Hidden
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * The memorized activation matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $output = null;
+    protected ?Matrix $output = null;
 
     /**
      * @param ActivationFunction $activationFn
diff --git a/src/NeuralNet/Layers/BatchNorm.php b/src/NeuralNet/Layers/BatchNorm.php
index bc720dc68..d1a8e8631 100644
--- a/src/NeuralNet/Layers/BatchNorm.php
+++ b/src/NeuralNet/Layers/BatchNorm.php
@@ -45,14 +45,14 @@ class BatchNorm implements Hidden, Parametric
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $betaInitializer;
+    protected Initializer $betaInitializer;
 
     /**
      * The initializer for the gamma parameter.
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $gammaInitializer;
+    protected Initializer $gammaInitializer;
 
     /**
      * The width of the layer. i.e. the number of neurons.
@@ -66,14 +66,14 @@ class BatchNorm implements Hidden, Parametric
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $beta = null;
+    protected ?Parameter $beta = null;
 
     /**
      * The learnable scaling parameter.
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $gamma = null;
+    protected ?Parameter $gamma = null;
 
     /**
      * The running mean of each input dimension.
@@ -101,7 +101,7 @@ class BatchNorm implements Hidden, Parametric
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $xHat = null;
+    protected ?Matrix $xHat = null;
 
     /**
      * @param float $decay
diff --git a/src/NeuralNet/Layers/Binary.php b/src/NeuralNet/Layers/Binary.php
index fdd3d9807..109231823 100644
--- a/src/NeuralNet/Layers/Binary.php
+++ b/src/NeuralNet/Layers/Binary.php
@@ -41,28 +41,28 @@ class Binary implements Output
      *
      * @var ClassificationLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\ClassificationLoss $costFn;
+    protected ClassificationLoss $costFn;
 
     /**
      * The sigmoid activation function.
      *
      * @var Sigmoid
      */
-    protected \Rubix\ML\NeuralNet\ActivationFunctions\Sigmoid $sigmoid;
+    protected Sigmoid $sigmoid;
 
     /**
      * The memorized input matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * The memorized activation matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $output = null;
+    protected ?Matrix $output = null;
 
     /**
      * @param string[] $classes
diff --git a/src/NeuralNet/Layers/Continuous.php b/src/NeuralNet/Layers/Continuous.php
index b5be4fe29..938c0900a 100644
--- a/src/NeuralNet/Layers/Continuous.php
+++ b/src/NeuralNet/Layers/Continuous.php
@@ -28,14 +28,14 @@ class Continuous implements Output
      *
      * @var RegressionLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\RegressionLoss $costFn;
+    protected RegressionLoss $costFn;
 
     /**
      * The memorized input matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * @param \Rubix\ML\NeuralNet\CostFunctions\RegressionLoss|null $costFn
diff --git a/src/NeuralNet/Layers/Dense.php b/src/NeuralNet/Layers/Dense.php
index 677e1f942..4bcfcb0bb 100644
--- a/src/NeuralNet/Layers/Dense.php
+++ b/src/NeuralNet/Layers/Dense.php
@@ -54,35 +54,35 @@ class Dense implements Hidden, Parametric
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $weightInitializer;
+    protected Initializer $weightInitializer;
 
     /**
      * The bias initializer.
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $biasInitializer;
+    protected Initializer $biasInitializer;
 
     /**
      * The weights.
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $weights = null;
+    protected ?Parameter $weights = null;
 
     /**
      * The biases.
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $biases = null;
+    protected ?Parameter $biases = null;
 
     /**
      * The memorized inputs to the layer.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * @param int $neurons
diff --git a/src/NeuralNet/Layers/Dropout.php b/src/NeuralNet/Layers/Dropout.php
index ee8a9585c..3f888dbda 100644
--- a/src/NeuralNet/Layers/Dropout.php
+++ b/src/NeuralNet/Layers/Dropout.php
@@ -52,7 +52,7 @@ class Dropout implements Hidden
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $mask = null;
+    protected ?Matrix $mask = null;
 
     /**
      * @param float $ratio
diff --git a/src/NeuralNet/Layers/Multiclass.php b/src/NeuralNet/Layers/Multiclass.php
index 9415e7e08..f5073d2e9 100644
--- a/src/NeuralNet/Layers/Multiclass.php
+++ b/src/NeuralNet/Layers/Multiclass.php
@@ -41,28 +41,28 @@ class Multiclass implements Output
      *
      * @var ClassificationLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\ClassificationLoss $costFn;
+    protected ClassificationLoss $costFn;
 
     /**
      * The softmax activation function.
      *
      * @var Softmax
      */
-    protected \Rubix\ML\NeuralNet\ActivationFunctions\Softmax $softmax;
+    protected Softmax $softmax;
 
     /**
      * The memorized input matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * The memorized activation matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $output = null;
+    protected ?Matrix $output = null;
 
     /**
      * @param string[] $classes
diff --git a/src/NeuralNet/Layers/PReLU.php b/src/NeuralNet/Layers/PReLU.php
index e208703c9..c90eda9d9 100644
--- a/src/NeuralNet/Layers/PReLU.php
+++ b/src/NeuralNet/Layers/PReLU.php
@@ -32,7 +32,7 @@ class PReLU implements Hidden, Parametric
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $initializer;
+    protected Initializer $initializer;
 
     /**
      * The width of the layer.
@@ -46,14 +46,14 @@ class PReLU implements Hidden, Parametric
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $alpha = null;
+    protected ?Parameter $alpha = null;
 
     /**
      * The memoized input matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * @param \Rubix\ML\NeuralNet\Initializers\Initializer|null $initializer
diff --git a/src/NeuralNet/Layers/Swish.php b/src/NeuralNet/Layers/Swish.php
index 3a85e8c50..4ad02959d 100644
--- a/src/NeuralNet/Layers/Swish.php
+++ b/src/NeuralNet/Layers/Swish.php
@@ -33,14 +33,14 @@ class Swish implements Hidden, Parametric
      *
      * @var Initializer
      */
-    protected \Rubix\ML\NeuralNet\Initializers\Initializer $initializer;
+    protected Initializer $initializer;
 
     /**
      * The sigmoid activation function.
      *
      * @var Sigmoid
      */
-    protected \Rubix\ML\NeuralNet\ActivationFunctions\Sigmoid $sigmoid;
+    protected Sigmoid $sigmoid;
 
     /**
      * The width of the layer.
@@ -54,21 +54,21 @@ class Swish implements Hidden, Parametric
      *
      * @var \Rubix\ML\NeuralNet\Parameter|null
      */
-    protected ?\Rubix\ML\NeuralNet\Parameter $beta = null;
+    protected ?Parameter $beta = null;
 
     /**
      * The memoized input matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $input = null;
+    protected ?Matrix $input = null;
 
     /**
      * The memorized activation matrix.
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $output = null;
+    protected ?Matrix $output = null;
 
     /**
      * @param \Rubix\ML\NeuralNet\Initializers\Initializer|null $initializer
diff --git a/src/NeuralNet/Parameter.php b/src/NeuralNet/Parameter.php
index 202aa1e5b..39fc34c9a 100644
--- a/src/NeuralNet/Parameter.php
+++ b/src/NeuralNet/Parameter.php
@@ -35,7 +35,7 @@ class Parameter
      *
      * @var Tensor
      */
-    protected \Tensor\Tensor $param;
+    protected Tensor $param;
 
     /**
      * @param Tensor $param
diff --git a/src/PersistentModel.php b/src/PersistentModel.php
index a7964a8a7..ceb3880bc 100644
--- a/src/PersistentModel.php
+++ b/src/PersistentModel.php
@@ -28,21 +28,21 @@ class PersistentModel implements Estimator, Learner, Probabilistic, Scoring
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $base;
+    protected Learner $base;
 
     /**
      * The persister used to interface with the storage layer.
      *
      * @var Persister
      */
-    protected \Rubix\ML\Persisters\Persister $persister;
+    protected Persister $persister;
 
     /**
      * The object serializer.
      *
      * @var Serializer
      */
-    protected \Rubix\ML\Serializers\Serializer $serializer;
+    protected Serializer $serializer;
 
     /**
      * Factory method to restore the model from persistence.
diff --git a/src/Pipeline.php b/src/Pipeline.php
index 7a04e080c..62abc5c9b 100644
--- a/src/Pipeline.php
+++ b/src/Pipeline.php
@@ -43,7 +43,7 @@ class Pipeline implements Online, Probabilistic, Scoring, Persistable
      *
      * @var Estimator
      */
-    protected \Rubix\ML\Estimator $base;
+    protected Estimator $base;
 
     /**
      * Should we update the elastic transformers during partial train?
diff --git a/src/Regressors/Adaline.php b/src/Regressors/Adaline.php
index 605484353..fa29764a9 100644
--- a/src/Regressors/Adaline.php
+++ b/src/Regressors/Adaline.php
@@ -68,7 +68,7 @@ class Adaline implements Estimator, Learner, Online, RanksFeatures, Verbose, Per
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * The amount of L2 regularization applied to the weights of the output layer.
@@ -104,14 +104,14 @@ class Adaline implements Estimator, Learner, Online, RanksFeatures, Verbose, Per
      *
      * @var RegressionLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\RegressionLoss $costFn;
+    protected RegressionLoss $costFn;
 
     /**
      * The underlying neural network instance.
      *
      * @var \Rubix\ML\NeuralNet\FeedForward|null
      */
-    protected ?\Rubix\ML\NeuralNet\FeedForward $network = null;
+    protected ?FeedForward $network = null;
 
     /**
      * The loss at each epoch from the last training session.
diff --git a/src/Regressors/GradientBoost.php b/src/Regressors/GradientBoost.php
index 979812c8b..c7d78e913 100644
--- a/src/Regressors/GradientBoost.php
+++ b/src/Regressors/GradientBoost.php
@@ -85,7 +85,7 @@ class GradientBoost implements Estimator, Learner, RanksFeatures, Verbose, Persi
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $booster;
+    protected Learner $booster;
 
     /**
      * The learning rate of the ensemble i.e. the *shrinkage* applied to each step.
@@ -135,7 +135,7 @@ class GradientBoost implements Estimator, Learner, RanksFeatures, Verbose, Persi
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * An ensemble of weak regressors.
diff --git a/src/Regressors/KDNeighborsRegressor.php b/src/Regressors/KDNeighborsRegressor.php
index 1c2ec75da..7324002ce 100644
--- a/src/Regressors/KDNeighborsRegressor.php
+++ b/src/Regressors/KDNeighborsRegressor.php
@@ -58,7 +58,7 @@ class KDNeighborsRegressor implements Estimator, Learner, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The dimensionality of the training set.
diff --git a/src/Regressors/KNNRegressor.php b/src/Regressors/KNNRegressor.php
index be9390e6e..aeaaabe5c 100644
--- a/src/Regressors/KNNRegressor.php
+++ b/src/Regressors/KNNRegressor.php
@@ -62,7 +62,7 @@ class KNNRegressor implements Estimator, Learner, Online, Persistable
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The training samples.
diff --git a/src/Regressors/MLPRegressor.php b/src/Regressors/MLPRegressor.php
index 57cf7be97..426cbd754 100644
--- a/src/Regressors/MLPRegressor.php
+++ b/src/Regressors/MLPRegressor.php
@@ -84,7 +84,7 @@ class MLPRegressor implements Estimator, Learner, Online, Verbose, Persistable
      *
      * @var Optimizer
      */
-    protected \Rubix\ML\NeuralNet\Optimizers\Optimizer $optimizer;
+    protected Optimizer $optimizer;
 
     /**
      * The amount of L2 regularization applied to the weights of the output layer.
@@ -126,21 +126,21 @@ class MLPRegressor implements Estimator, Learner, Online, Verbose, Persistable
      *
      * @var RegressionLoss
      */
-    protected \Rubix\ML\NeuralNet\CostFunctions\RegressionLoss $costFn;
+    protected RegressionLoss $costFn;
 
     /**
      * The metric used to score the generalization performance of the model during training.
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * The underlying neural network instance.
      *
      * @var \Rubix\ML\NeuralNet\FeedForward|null
      */
-    protected ?\Rubix\ML\NeuralNet\FeedForward $network = null;
+    protected ?FeedForward $network = null;
 
     /**
      * The validation scores at each epoch from the last training session.
diff --git a/src/Regressors/RadiusNeighborsRegressor.php b/src/Regressors/RadiusNeighborsRegressor.php
index 4748acfc6..2075e7b2e 100644
--- a/src/Regressors/RadiusNeighborsRegressor.php
+++ b/src/Regressors/RadiusNeighborsRegressor.php
@@ -66,7 +66,7 @@ class RadiusNeighborsRegressor implements Estimator, Learner, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The dimensionality of the training set.
diff --git a/src/Regressors/Ridge.php b/src/Regressors/Ridge.php
index 329b3935c..999d3afd5 100644
--- a/src/Regressors/Ridge.php
+++ b/src/Regressors/Ridge.php
@@ -58,7 +58,7 @@ class Ridge implements Estimator, Learner, RanksFeatures, Persistable
      *
      * @var \Tensor\Vector|null
      */
-    protected ?\Tensor\Vector $coefficients = null;
+    protected ?Vector $coefficients = null;
 
     /**
      * @param float $l2Penalty
diff --git a/src/Regressors/SVR.php b/src/Regressors/SVR.php
index a289b1953..5967f6678 100644
--- a/src/Regressors/SVR.php
+++ b/src/Regressors/SVR.php
@@ -50,7 +50,7 @@ class SVR implements Estimator, Learner
      *
      * @var svm
      */
-    protected \svm $svm;
+    protected svm $svm;
 
     /**
      * The memoized hyper-parameters of the model.
@@ -64,7 +64,7 @@ class SVR implements Estimator, Learner
      *
      * @var \svmmodel|null
      */
-    protected ?\svmmodel $model = null;
+    protected ?svmmodel $model = null;
 
     /**
      * @param float $c
diff --git a/src/Serializers/GzipNative.php b/src/Serializers/GzipNative.php
index 24ae98585..f55134378 100644
--- a/src/Serializers/GzipNative.php
+++ b/src/Serializers/GzipNative.php
@@ -34,7 +34,7 @@ class GzipNative implements Serializer
      *
      * @var Native
      */
-    protected \Rubix\ML\Serializers\Native $base;
+    protected Native $base;
 
     /**
      * @param int $level
diff --git a/src/Serializers/RBX.php b/src/Serializers/RBX.php
index 5e9b9999b..4ba5d9e94 100644
--- a/src/Serializers/RBX.php
+++ b/src/Serializers/RBX.php
@@ -64,7 +64,7 @@ class RBX implements Serializer
      *
      * @var GzipNative
      */
-    protected \Rubix\ML\Serializers\GzipNative $base;
+    protected GzipNative $base;
 
     /**
      * @param int $level
diff --git a/src/Specifications/DatasetHasDimensionality.php b/src/Specifications/DatasetHasDimensionality.php
index bb71b086c..cf08ae837 100644
--- a/src/Specifications/DatasetHasDimensionality.php
+++ b/src/Specifications/DatasetHasDimensionality.php
@@ -16,7 +16,7 @@ class DatasetHasDimensionality extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * The target dimensionality.
diff --git a/src/Specifications/DatasetIsLabeled.php b/src/Specifications/DatasetIsLabeled.php
index 7ebf4e56d..55614bc99 100644
--- a/src/Specifications/DatasetIsLabeled.php
+++ b/src/Specifications/DatasetIsLabeled.php
@@ -16,7 +16,7 @@ class DatasetIsLabeled extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/DatasetIsNotEmpty.php b/src/Specifications/DatasetIsNotEmpty.php
index be7048efc..8e53ea129 100644
--- a/src/Specifications/DatasetIsNotEmpty.php
+++ b/src/Specifications/DatasetIsNotEmpty.php
@@ -15,7 +15,7 @@ class DatasetIsNotEmpty extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/EstimatorIsCompatibleWithMetric.php b/src/Specifications/EstimatorIsCompatibleWithMetric.php
index 16dd51b52..47a4db9de 100644
--- a/src/Specifications/EstimatorIsCompatibleWithMetric.php
+++ b/src/Specifications/EstimatorIsCompatibleWithMetric.php
@@ -18,14 +18,14 @@ class EstimatorIsCompatibleWithMetric extends Specification
      *
      * @var Estimator
      */
-    protected \Rubix\ML\Estimator $estimator;
+    protected Estimator $estimator;
 
     /**
      * The validation metric.
      *
      * @var Metric
      */
-    protected \Rubix\ML\CrossValidation\Metrics\Metric $metric;
+    protected Metric $metric;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/LabelsAreCompatibleWithLearner.php b/src/Specifications/LabelsAreCompatibleWithLearner.php
index d207a0577..23e8f70d5 100644
--- a/src/Specifications/LabelsAreCompatibleWithLearner.php
+++ b/src/Specifications/LabelsAreCompatibleWithLearner.php
@@ -18,14 +18,14 @@ class LabelsAreCompatibleWithLearner extends Specification
      *
      * @var Labeled
      */
-    protected \Rubix\ML\Datasets\Labeled $dataset;
+    protected Labeled $dataset;
 
     /**
      * The learner instance.
      *
      * @var Learner
      */
-    protected \Rubix\ML\Learner $estimator;
+    protected Learner $estimator;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/SamplesAreCompatibleWithDistance.php b/src/Specifications/SamplesAreCompatibleWithDistance.php
index 30af77575..047c34bb6 100644
--- a/src/Specifications/SamplesAreCompatibleWithDistance.php
+++ b/src/Specifications/SamplesAreCompatibleWithDistance.php
@@ -18,14 +18,14 @@ class SamplesAreCompatibleWithDistance extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * The distance kernel.
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/SamplesAreCompatibleWithEstimator.php b/src/Specifications/SamplesAreCompatibleWithEstimator.php
index 07d78a520..5383fbb4a 100644
--- a/src/Specifications/SamplesAreCompatibleWithEstimator.php
+++ b/src/Specifications/SamplesAreCompatibleWithEstimator.php
@@ -18,14 +18,14 @@ class SamplesAreCompatibleWithEstimator extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * The estimator.
      *
      * @var Estimator
      */
-    protected \Rubix\ML\Estimator $estimator;
+    protected Estimator $estimator;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/SamplesAreCompatibleWithTransformer.php b/src/Specifications/SamplesAreCompatibleWithTransformer.php
index 0396d491e..c5e601d07 100644
--- a/src/Specifications/SamplesAreCompatibleWithTransformer.php
+++ b/src/Specifications/SamplesAreCompatibleWithTransformer.php
@@ -18,14 +18,14 @@ class SamplesAreCompatibleWithTransformer extends Specification
      *
      * @var Dataset
      */
-    protected \Rubix\ML\Datasets\Dataset $dataset;
+    protected Dataset $dataset;
 
     /**
      * The transformer.
      *
      * @var Transformer
      */
-    protected \Rubix\ML\Transformers\Transformer $transformer;
+    protected Transformer $transformer;
 
     /**
      * Build a specification object with the given arguments.
diff --git a/src/Specifications/SwooleExtensionIsLoaded.php b/src/Specifications/SwooleExtensionIsLoaded.php
index d2179ef51..d15342649 100644
--- a/src/Specifications/SwooleExtensionIsLoaded.php
+++ b/src/Specifications/SwooleExtensionIsLoaded.php
@@ -15,7 +15,7 @@ public static function create() : self
     }
 
     /**
-     * @throws \Rubix\ML\Exceptions\MissingExtension
+     * @throws MissingExtension
      */
     public function check() : void
     {
diff --git a/src/Tokenizers/KSkipNGram.php b/src/Tokenizers/KSkipNGram.php
index d51f13529..e77884b97 100644
--- a/src/Tokenizers/KSkipNGram.php
+++ b/src/Tokenizers/KSkipNGram.php
@@ -57,14 +57,14 @@ class KSkipNGram implements Tokenizer
      *
      * @var Word
      */
-    protected \Rubix\ML\Tokenizers\Word $wordTokenizer;
+    protected Word $wordTokenizer;
 
     /**
      * The sentence tokenizer.
      *
      * @var Sentence
      */
-    protected \Rubix\ML\Tokenizers\Sentence $sentenceTokenizer;
+    protected Sentence $sentenceTokenizer;
 
     /**
      * @param int $min
diff --git a/src/Tokenizers/NGram.php b/src/Tokenizers/NGram.php
index 92becb5d9..744959029 100644
--- a/src/Tokenizers/NGram.php
+++ b/src/Tokenizers/NGram.php
@@ -46,14 +46,14 @@ class NGram implements Tokenizer
      *
      * @var Word
      */
-    protected \Rubix\ML\Tokenizers\Word $wordTokenizer;
+    protected Word $wordTokenizer;
 
     /**
      * The sentence tokenizer.
      *
      * @var Sentence
      */
-    protected \Rubix\ML\Tokenizers\Sentence $sentenceTokenizer;
+    protected Sentence $sentenceTokenizer;
 
     /**
      * @param int $min
diff --git a/src/Traits/LoggerAware.php b/src/Traits/LoggerAware.php
index 371da7271..b08e30219 100644
--- a/src/Traits/LoggerAware.php
+++ b/src/Traits/LoggerAware.php
@@ -20,7 +20,7 @@ trait LoggerAware
      *
      * @var \Psr\Log\LoggerInterface|null
      */
-    protected ?\Psr\Log\LoggerInterface $logger = null;
+    protected ?LoggerInterface $logger = null;
 
     /**
      * Sets a PSR-3 logger instance.
diff --git a/src/Traits/Multiprocessing.php b/src/Traits/Multiprocessing.php
index a9d1b9b28..de1e862ee 100644
--- a/src/Traits/Multiprocessing.php
+++ b/src/Traits/Multiprocessing.php
@@ -27,7 +27,7 @@ trait Multiprocessing
      *
      * @var Backend
      */
-    protected \Rubix\ML\Backends\Backend $backend;
+    protected Backend $backend;
 
     /**
      * Set the parallel processing backend.
diff --git a/src/Transformers/GaussianRandomProjector.php b/src/Transformers/GaussianRandomProjector.php
index 9af543c8f..ae383213b 100644
--- a/src/Transformers/GaussianRandomProjector.php
+++ b/src/Transformers/GaussianRandomProjector.php
@@ -41,7 +41,7 @@ class GaussianRandomProjector implements Transformer, Stateful, Persistable
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $r = null;
+    protected ?Matrix $r = null;
 
     /**
      * Estimate the minimum dimensionality needed to satisfy a *max distortion* constraint with *n*
diff --git a/src/Transformers/HotDeckImputer.php b/src/Transformers/HotDeckImputer.php
index 8d1c3183d..9d6633815 100644
--- a/src/Transformers/HotDeckImputer.php
+++ b/src/Transformers/HotDeckImputer.php
@@ -73,7 +73,7 @@ class HotDeckImputer implements Transformer, Stateful, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * @param int $k
diff --git a/src/Transformers/KNNImputer.php b/src/Transformers/KNNImputer.php
index 9415940cb..8bac119ab 100644
--- a/src/Transformers/KNNImputer.php
+++ b/src/Transformers/KNNImputer.php
@@ -73,7 +73,7 @@ class KNNImputer implements Transformer, Stateful, Persistable
      *
      * @var Spatial
      */
-    protected \Rubix\ML\Graph\Trees\Spatial $tree;
+    protected Spatial $tree;
 
     /**
      * The data types of the fitted feature columns.
diff --git a/src/Transformers/LinearDiscriminantAnalysis.php b/src/Transformers/LinearDiscriminantAnalysis.php
index dc024fad2..1a1164d66 100644
--- a/src/Transformers/LinearDiscriminantAnalysis.php
+++ b/src/Transformers/LinearDiscriminantAnalysis.php
@@ -49,7 +49,7 @@ class LinearDiscriminantAnalysis implements Transformer, Stateful, Persistable
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $eigenvectors = null;
+    protected ?Matrix $eigenvectors = null;
 
     /**
      * The percentage of information lost due to the transformation.
diff --git a/src/Transformers/MissingDataImputer.php b/src/Transformers/MissingDataImputer.php
index 5175ed0f4..71b4cb337 100644
--- a/src/Transformers/MissingDataImputer.php
+++ b/src/Transformers/MissingDataImputer.php
@@ -34,14 +34,14 @@ class MissingDataImputer implements Transformer, Stateful, Persistable
      *
      * @var Strategy
      */
-    protected \Rubix\ML\Strategies\Strategy $continuous;
+    protected Strategy $continuous;
 
     /**
      * The guessing strategy to use when imputing categorical values.
      *
      * @var Strategy
      */
-    protected \Rubix\ML\Strategies\Strategy $categorical;
+    protected Strategy $categorical;
 
     /**
      * The placeholder category that denotes missing values.
diff --git a/src/Transformers/PrincipalComponentAnalysis.php b/src/Transformers/PrincipalComponentAnalysis.php
index aeabdbc2d..896795d86 100644
--- a/src/Transformers/PrincipalComponentAnalysis.php
+++ b/src/Transformers/PrincipalComponentAnalysis.php
@@ -53,7 +53,7 @@ class PrincipalComponentAnalysis implements Transformer, Stateful, Persistable
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $eigenvectors = null;
+    protected ?Matrix $eigenvectors = null;
 
     /**
      * The percentage of information lost due to the transformation.
diff --git a/src/Transformers/TSNE.php b/src/Transformers/TSNE.php
index b12407e4f..dc39961fb 100644
--- a/src/Transformers/TSNE.php
+++ b/src/Transformers/TSNE.php
@@ -190,7 +190,7 @@ class TSNE implements Transformer, Verbose
      *
      * @var Distance
      */
-    protected \Rubix\ML\Kernels\Distance\Distance $kernel;
+    protected Distance $kernel;
 
     /**
      * The loss at each epoch from the last embedding.
diff --git a/src/Transformers/TokenHashingVectorizer.php b/src/Transformers/TokenHashingVectorizer.php
index ca8f7c56a..a0eb0d45b 100644
--- a/src/Transformers/TokenHashingVectorizer.php
+++ b/src/Transformers/TokenHashingVectorizer.php
@@ -70,7 +70,7 @@ class TokenHashingVectorizer implements Transformer
      *
      * @var Tokenizer
      */
-    protected \Rubix\ML\Tokenizers\Tokenizer $tokenizer;
+    protected Tokenizer $tokenizer;
 
     /**
      * The hash function that accepts a string token and returns an integer.
diff --git a/src/Transformers/TruncatedSVD.php b/src/Transformers/TruncatedSVD.php
index 399bf7f05..143f570be 100644
--- a/src/Transformers/TruncatedSVD.php
+++ b/src/Transformers/TruncatedSVD.php
@@ -49,7 +49,7 @@ class TruncatedSVD implements Transformer, Stateful, Persistable
      *
      * @var \Tensor\Matrix|null
      */
-    protected ?\Tensor\Matrix $components = null;
+    protected ?Matrix $components = null;
 
     /**
      * The proportion of information lost due to the transformation.
diff --git a/src/Transformers/WordCountVectorizer.php b/src/Transformers/WordCountVectorizer.php
index 3c79c9a7f..9545f560b 100644
--- a/src/Transformers/WordCountVectorizer.php
+++ b/src/Transformers/WordCountVectorizer.php
@@ -62,7 +62,7 @@ class WordCountVectorizer implements Transformer, Stateful, Persistable
      *
      * @var Tokenizer
      */
-    protected \Rubix\ML\Tokenizers\Tokenizer $tokenizer;
+    protected Tokenizer $tokenizer;
 
     /**
      * The vocabularies of each categorical feature column of the fitted dataset.
diff --git a/tests/Backends/SwooleTest.php b/tests/Backends/SwooleTest.php
index 60cbf526f..ab6ac6cb1 100644
--- a/tests/Backends/SwooleTest.php
+++ b/tests/Backends/SwooleTest.php
@@ -17,7 +17,7 @@
 class SwooleTest extends TestCase
 {
     /**
-     * @var \Rubix\ML\Backends\Swoole
+     * @var SwooleBackend
      */
     protected $backend;
 
diff --git a/tests/Graph/Nodes/NeighborhoodTest.php b/tests/Graph/Nodes/NeighborhoodTest.php
index d2f17fb91..755957c2f 100644
--- a/tests/Graph/Nodes/NeighborhoodTest.php
+++ b/tests/Graph/Nodes/NeighborhoodTest.php
@@ -63,7 +63,7 @@ public function terminate() : void
     {
         $node = Neighborhood::terminate(Labeled::quick(self::SAMPLES, self::LABELS));
 
-        $this->assertInstanceOf(NeighborHood::class, $node);
+        $this->assertInstanceOf(Neighborhood::class, $node);
         $this->assertInstanceOf(Labeled::class, $node->dataset());
         $this->assertEquals(self::BOX, iterator_to_array($node->sides()));
     }
diff --git a/tests/NeuralNet/ParameterTest.php b/tests/NeuralNet/ParameterTest.php
index 80fc03603..ec54adc51 100644
--- a/tests/NeuralNet/ParameterTest.php
+++ b/tests/NeuralNet/ParameterTest.php
@@ -16,7 +16,7 @@ class ParameterTest extends TestCase
     /**
      * @var Parameter
      */
-    protected \Rubix\ML\NeuralNet\Parameter $param;
+    protected Parameter $param;
 
     /**
      * @var \Rubix\ML\NeuralNet\Optimizers\Optimizer
diff --git a/tests/Transformers/ImageRotatorTest.php b/tests/Transformers/ImageRotatorTest.php
index 13772f54e..10ccd5bef 100644
--- a/tests/Transformers/ImageRotatorTest.php
+++ b/tests/Transformers/ImageRotatorTest.php
@@ -17,7 +17,7 @@ class ImageRotatorTest extends TestCase
     /**
      * @var ImageRotator
      */
-    protected \Rubix\ML\Transformers\ImageRotator $transformer;
+    protected ImageRotator $transformer;
 
     /**
      * @before

From 251a1b46693939d26b24d86360f8fc630261bfec Mon Sep 17 00:00:00 2001
From: Mateusz Charytoniuk <mateusz.charytoniuk@protonmail.com>
Date: Sat, 16 Mar 2024 15:58:51 +0100
Subject: [PATCH 18/18] docs: Swoole backend

---
 docs/backends/swoole.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 docs/backends/swoole.md

diff --git a/docs/backends/swoole.md b/docs/backends/swoole.md
new file mode 100644
index 000000000..b49b09e78
--- /dev/null
+++ b/docs/backends/swoole.md
@@ -0,0 +1,18 @@
+<span style="float:right;"><a href="https://github.com/RubixML/ML/blob/master/src/Backends/Swoole.php">[source]</a></span>
+
+# Swoole
+[Swoole](https://swoole.com)/[OpenSwoole](https://openswoole.com/) is an async PHP extension that also supports multiprocessing.
+
+!!! tip
+    Swoole backend makes use of [Igbinary](https://www.php.net/manual/en/intro.igbinary.php) serializer. If you need to
+    optimize the memory usage (or getting out-of-memory errors) consider installing [Igbinary](https://www.php.net/manual/en/intro.igbinary.php).
+
+## Example
+
+No parameters are required. It's a drop-in replacement for the [Serial](backends/serial.md) backend.
+
+```php
+use Rubix\ML\Backends\Swoole;
+
+$backend = new Swoole();
+```
\ No newline at end of file