Redesign of Collector architecture (#901).

Signed-off-by: Marcin Kielar <[email protected]>

examples/example-exporter-multi-target/src/main/java/io/prometheus/metrics/examples/multitarget/Main.java

@@ -12,7 +12,7 @@ public class Main {
 
     public static void main(String[] args) throws IOException, InterruptedException {
 
-        SampleMultiCollector xmc = new SampleMultiCollector();
+        SampleCollector xmc = new SampleCollector();
         PrometheusRegistry.defaultRegistry.register(xmc);
         HTTPServer server = HTTPServer.builder()
                 .port(9401)

examples/example-exporter-multi-target/src/main/java/io/prometheus/metrics/examples/multitarget/SampleMultiCollector.java → examples/example-exporter-multi-target/src/main/java/io/prometheus/metrics/examples/multitarget/SampleCollector.java

@@ -1,37 +1,23 @@
 package io.prometheus.metrics.examples.multitarget;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
+import java.util.function.Predicate;
 
-import io.prometheus.metrics.model.registry.MultiCollector;
+import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.PrometheusScrapeRequest;
 import io.prometheus.metrics.model.snapshots.CounterSnapshot;
 import io.prometheus.metrics.model.snapshots.CounterSnapshot.CounterDataPointSnapshot.Builder;
 import io.prometheus.metrics.model.snapshots.GaugeSnapshot;
 import io.prometheus.metrics.model.snapshots.Labels;
-import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
 import io.prometheus.metrics.model.snapshots.PrometheusNaming;
 
-public class SampleMultiCollector implements MultiCollector {
-
-	public SampleMultiCollector() {
-		super();
-	}
-
-	@Override
-	public MetricSnapshots collect() {
-		return new MetricSnapshots();
-	}
-
+public class SampleCollector implements Collector {
 	@Override
-	public MetricSnapshots collect(PrometheusScrapeRequest scrapeRequest) {
-		return collectMetricSnapshots(scrapeRequest);
+	public MetricSnapshots collect(Predicate<String> nameFilter, PrometheusScrapeRequest scrapeRequest) {
+		return collectMetricSnapshots(scrapeRequest).filter(nameFilter);
 	}
 
 	protected MetricSnapshots collectMetricSnapshots(PrometheusScrapeRequest scrapeRequest) {
-
 		GaugeSnapshot.Builder gaugeBuilder = GaugeSnapshot.builder();
 		gaugeBuilder.name("x_load").help("process load");
 
@@ -71,18 +57,7 @@ protected MetricSnapshots collectMetricSnapshots(PrometheusScrapeRequest scrapeR
 				gaugeBuilder.dataPoint(gaugeDataPointBuilder.build());
 			}
 		}
-		Collection<MetricSnapshot> snaps = new ArrayList<MetricSnapshot>();
-		snaps.add(counterBuilder.build());
-		snaps.add(gaugeBuilder.build());
-		MetricSnapshots msnaps = new MetricSnapshots(snaps);
+		MetricSnapshots msnaps = new MetricSnapshots(counterBuilder.build(), gaugeBuilder.build());
 		return msnaps;
 	}
-
-	public List<String> getPrometheusNames() {
-		List<String> names = new ArrayList<String>();
-		names.add("x_calls_total");
-		names.add("x_load");
-		return names;
-	}
-
 }

integration-tests/it-exporter/it-exporter-httpserver-sample/src/main/java/io/prometheus/metrics/it/exporter/httpserver/HTTPServerSample.java

@@ -4,9 +4,9 @@
 import io.prometheus.metrics.core.metrics.Gauge;
 import io.prometheus.metrics.core.metrics.Info;
 import io.prometheus.metrics.exporter.httpserver.HTTPServer;
+import io.prometheus.metrics.model.registry.CollectorBuilder;
 import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
-import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.Unit;
 
 import java.io.IOException;
@@ -53,9 +53,9 @@ public static void main(String[] args) throws IOException, InterruptedException
         gauge.labelValues("outside").set(27.0);
 
         if (mode == Mode.error) {
-            Collector failingCollector = () -> {
+            Collector failingCollector = CollectorBuilder.fromMetric(() -> {
                 throw new RuntimeException("Simulating an error.");
-            };
+            });
 
             PrometheusRegistry.defaultRegistry.register(failingCollector);
         }

integration-tests/it-exporter/it-exporter-servlet-jetty-sample/src/main/java/io/prometheus/metrics/it/exporter/servlet/jetty/ExporterServletJettySample.java

@@ -4,9 +4,9 @@
 import io.prometheus.metrics.core.metrics.Gauge;
 import io.prometheus.metrics.core.metrics.Info;
 import io.prometheus.metrics.exporter.servlet.jakarta.PrometheusMetricsServlet;
+import io.prometheus.metrics.model.registry.CollectorBuilder;
 import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
-import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.Unit;
 import org.eclipse.jetty.server.Connector;
 import org.eclipse.jetty.server.Server;
@@ -57,9 +57,9 @@ public static void main(String[] args) throws Exception {
         gauge.labelValues("outside").set(27.0);
 
         if (mode == Mode.error) {
-            Collector failingCollector = () -> {
+            Collector failingCollector = CollectorBuilder.fromMetrics(() -> {
                 throw new RuntimeException("Simulating an error.");
-            };
+            });
 
             PrometheusRegistry.defaultRegistry.register(failingCollector);
         }

integration-tests/it-exporter/it-exporter-servlet-tomcat-sample/src/main/java/io/prometheus/metrics/it/exporter/servlet/tomcat/ExporterServletTomcatSample.java

@@ -4,9 +4,9 @@
 import io.prometheus.metrics.core.metrics.Gauge;
 import io.prometheus.metrics.core.metrics.Info;
 import io.prometheus.metrics.exporter.servlet.jakarta.PrometheusMetricsServlet;
+import io.prometheus.metrics.model.registry.CollectorBuilder;
 import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
-import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.Unit;
 import org.apache.catalina.Context;
 import org.apache.catalina.LifecycleException;
@@ -61,9 +61,9 @@ public static void main(String[] args) throws LifecycleException, IOException {
         gauge.labelValues("outside").set(27.0);
 
         if (mode == Mode.error) {
-            Collector failingCollector = () -> {
+            Collector failingCollector = CollectorBuilder.fromMetrics(() -> {
                 throw new RuntimeException("Simulating an error.");
-            };
+            });
 
             PrometheusRegistry.defaultRegistry.register(failingCollector);
         }

prometheus-metrics-core/pom.xml

@@ -19,6 +19,18 @@
     <properties>
         <automatic.module.name>io.prometheus.metrics.core</automatic.module.name>
     </properties>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>16</source>
+                    <target>16</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 
     <licenses>
         <license>

prometheus-metrics-core/src/main/java/io/prometheus/metrics/core/metrics/Metric.java

@@ -2,6 +2,7 @@
 
 import io.prometheus.metrics.config.PrometheusProperties;
 import io.prometheus.metrics.model.registry.Collector;
+import io.prometheus.metrics.model.registry.CollectorBuilder;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
 import io.prometheus.metrics.model.snapshots.Label;
 import io.prometheus.metrics.model.snapshots.Labels;
@@ -21,9 +22,6 @@ protected Metric(Builder<?, ?> builder) {
         this.constLabels = builder.constLabels;
     }
 
-    @Override
-    public abstract MetricSnapshot collect();
-
     protected static abstract class Builder<B extends Builder<B, M>, M extends Metric> {
 
         protected final List<String> illegalLabelNames;

prometheus-metrics-core/src/main/java/io/prometheus/metrics/core/metrics/MetricWithFixedMetadata.java

@@ -1,13 +1,15 @@
 package io.prometheus.metrics.core.metrics;
 
 import io.prometheus.metrics.config.PrometheusProperties;
-import io.prometheus.metrics.model.snapshots.Labels;
-import io.prometheus.metrics.model.snapshots.MetricMetadata;
-import io.prometheus.metrics.model.snapshots.PrometheusNaming;
-import io.prometheus.metrics.model.snapshots.Unit;
+import io.prometheus.metrics.model.registry.Collector;
+import io.prometheus.metrics.model.registry.CollectorBuilder;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
+import io.prometheus.metrics.model.registry.PrometheusScrapeRequest;
+import io.prometheus.metrics.model.snapshots.*;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Predicate;
 
 /**
  * Almost all metrics have fixed metadata, i.e. the metric name is known when the metric is created.
@@ -30,6 +32,15 @@ protected MetricMetadata getMetadata() {
         return metadata;
     }
 
+    protected abstract MetricSnapshot collect();
+
+    public MetricSnapshots collect(Predicate<String> includedNames, PrometheusScrapeRequest scrapeRequest) {
+        if(includedNames.test(this.metadata.getPrometheusName()))
+            return MetricSnapshots.of(collect());
+        else
+            return MetricSnapshots.empty();
+    }
+
     private String makeName(String name, Unit unit) {
         if (unit != null) {
             if (!name.endsWith(unit.toString())) {
@@ -39,11 +50,6 @@ private String makeName(String name, Unit unit) {
         return name;
     }
 
-    @Override
-    public String getPrometheusName() {
-        return metadata.getPrometheusName();
-    }
-
     public static abstract class Builder<B extends Builder<B, M>, M extends MetricWithFixedMetadata> extends Metric.Builder<B, M> {
 
         protected String name;

prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/NameFilterTest.java

@@ -0,0 +1,61 @@
+package io.prometheus.metrics.core.metrics;
+
+import io.prometheus.metrics.model.registry.MetricNameFilter;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class NameFilterTest {
+    @Test
+    public void testCounterWithCallback() {
+        AtomicInteger accessCount = new AtomicInteger();
+        CounterWithCallback metrics = CounterWithCallback.builder()
+                .name("my_counter")
+                .callback(cb -> {
+                    accessCount.incrementAndGet();
+                    cb.call(1.0);
+                })
+                .build();
+
+
+        PrometheusRegistry registry = new PrometheusRegistry();
+        registry.register(metrics);
+
+        var result1 = registry.scrape(MetricNameFilter.builder().nameMustBeEqualTo("XXX").build());
+        Assert.assertEquals(accessCount.get(), 0);
+        Assert.assertTrue(result1.stream().toList().isEmpty());
+
+        var result2 = registry.scrape(MetricNameFilter.builder().nameMustBeEqualTo("my_counter").build());
+        Assert.assertEquals(accessCount.get(), 1);
+        Assert.assertEquals(result2.stream().toList().size(), 1);
+        Assert.assertEquals(result2.get(0).getMetadata().getPrometheusName(), "my_counter");
+    }
+
+    @Test
+    public void testGaugeWithCallback() {
+        AtomicInteger accessCount = new AtomicInteger();
+        GaugeWithCallback metrics = GaugeWithCallback.builder()
+                .name("my_gauge")
+                .callback(cb -> {
+                    accessCount.incrementAndGet();
+                    cb.call(1.0);
+                })
+                .build();
+
+
+        PrometheusRegistry registry = new PrometheusRegistry();
+        registry.register(metrics);
+
+        var result1 = registry.scrape(MetricNameFilter.builder().nameMustBeEqualTo("XXX").build());
+        Assert.assertEquals(accessCount.get(), 0);
+        Assert.assertTrue(result1.stream().toList().isEmpty());
+
+        var result2 = registry.scrape(MetricNameFilter.builder().nameMustBeEqualTo("my_gauge").build());
+        Assert.assertEquals(accessCount.get(), 1);
+        Assert.assertEquals(result2.stream().toList().size(), 1);
+        Assert.assertEquals(result2.get(0).getMetadata().getPrometheusName(), "my_gauge");
+    }
+
+}

prometheus-metrics-exporter-common/src/main/java/io/prometheus/metrics/exporter/common/PrometheusScrapeHandler.java

@@ -4,6 +4,7 @@
 import io.prometheus.metrics.config.PrometheusProperties;
 import io.prometheus.metrics.expositionformats.ExpositionFormatWriter;
 import io.prometheus.metrics.expositionformats.ExpositionFormats;
+import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.MetricNameFilter;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
@@ -23,7 +24,7 @@
  */
 public class PrometheusScrapeHandler {
 
-    private final PrometheusRegistry registry;
+    private final Collector registry;
     private final ExpositionFormats expositionFormats;
     private final Predicate<String> nameFilter;
     private AtomicInteger lastResponseSize = new AtomicInteger(2 << 9); //  0.5 MB
@@ -32,15 +33,15 @@ public PrometheusScrapeHandler() {
         this(PrometheusProperties.get(), PrometheusRegistry.defaultRegistry);
     }
 
-    public PrometheusScrapeHandler(PrometheusRegistry registry) {
+    public PrometheusScrapeHandler(Collector registry) {
         this(PrometheusProperties.get(), registry);
     }
 
     public PrometheusScrapeHandler(PrometheusProperties config) {
         this(config, PrometheusRegistry.defaultRegistry);
     }
 
-    public PrometheusScrapeHandler(PrometheusProperties config, PrometheusRegistry registry) {
+    public PrometheusScrapeHandler(PrometheusProperties config, Collector registry) {
         this.expositionFormats = ExpositionFormats.init(config.getExporterProperties());
         this.registry = registry;
         this.nameFilter = makeNameFilter(config.getExporterFilterProperties());
@@ -106,15 +107,11 @@ private Predicate<String> makeNameFilter(ExporterFilterProperties props) {
     private MetricSnapshots scrape(PrometheusHttpRequest request) {
 
         Predicate<String> filter = makeNameFilter(request.getParameterValues("name[]"));
-        if (filter != null) {
-            return registry.scrape(filter, request);
-        } else {
-            return registry.scrape(request);
-        }
+        return registry.collect(filter, request);
     }
 
     private Predicate<String> makeNameFilter(String[] includedNames) {
-        Predicate<String> result = null;
+        Predicate<String> result = MetricNameFilter.ALLOW_ALL;
         if (includedNames != null && includedNames.length > 0) {
             result = MetricNameFilter.builder().nameMustBeEqualTo(includedNames).build();
         }

prometheus-metrics-exporter-httpserver/src/main/java/io/prometheus/metrics/exporter/httpserver/MetricsHandler.java

@@ -4,6 +4,7 @@
 import com.sun.net.httpserver.HttpHandler;
 import io.prometheus.metrics.config.PrometheusProperties;
 import io.prometheus.metrics.exporter.common.PrometheusScrapeHandler;
+import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.PrometheusRegistry;
 
 import java.io.ByteArrayOutputStream;
@@ -26,7 +27,7 @@ public MetricsHandler() {
         prometheusScrapeHandler = new PrometheusScrapeHandler();
     }
 
-    public MetricsHandler(PrometheusRegistry registry) {
+    public MetricsHandler(Collector registry) {
         prometheusScrapeHandler = new PrometheusScrapeHandler(registry);
     }
 

prometheus-metrics-instrumentation-jvm/pom.xml

@@ -19,6 +19,18 @@
     <properties>
         <automatic.module.name>io.prometheus.metrics.instrumentation.jvm</automatic.module.name>
     </properties>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>10</source>
+                    <target>10</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 
     <licenses>
         <license>