Merge pull request #19 from felixlehmann/sighup-handling

Add SIGHUP handling for graceful exit of worker

Author: lorenzo

README.md

@@ -161,3 +161,9 @@ messages are received from a set of queues in CakeSQS. This is an example
 The functions registered to handle jobs will receive the message body from the queue after decoding it using `json_decode`.
 
 IMPORTANT: return true to delete the message upon processing, false to leave the message in the queue and re - process later
+
+## Kill worker softly with SIGHUP
+
+To kill a long lived worker shell in the middle of the iterations loop, you can send SIGHUP by calling `kill -1 PID` on the commandline (PID is the process Id of your running worker shell).
+
+This will cause the current iteration to finish and stop the worker afterwards.

src/Shell/Task/QueueWorkerTask.php

@@ -34,6 +34,13 @@ class QueueWorkerTask extends Shell
      */
     protected $callbacks = [];
 
+    /**
+     * Exit signal
+     *
+     * @var bool
+     */
+    private $exit = false;
+
     /**
      * Read the queue and process messages, this work process will block for a number of
      * iterations, so can set this work process to last forever setting the $iterations param
@@ -48,6 +55,13 @@ class QueueWorkerTask extends Shell
     public function work($name = 'default', $iterations = self::MAX_MESSAGES_PROCESSED)
     {
         $this->log(sprintf("Starting %s worker", $name), 'info', 'sqs');
+
+        if (function_exists('pcntl_signal')) {
+            pcntl_signal(SIGHUP, function () {
+                $this->exit = true;
+            });
+        }
+
         $simpleQueue = $this->getSimpleQueue();
         $i = 0;
         $infinite_loop = ($iterations == -1);
@@ -69,6 +83,15 @@ public function work($name = 'default', $iterations = self::MAX_MESSAGES_PROCESS
             if ($iterations > -1) {
                 $i++;
             }
+
+            if (function_exists('pcntl_signal_dispatch')) {
+                pcntl_signal_dispatch();
+            }
+
+            if ($this->exit == true) {
+                $this->log(sprintf("SIGHUP Received in iteration %d of %d", $i, $iterations), 'info', 'sqs');
+                break 1;
+            }
         }
         $this->log(sprintf("Finished %s worker", $name), 'info', 'sqs');
     }