Implement C3P0 connection pool metrics

instrumentation/c3p0-0.9/javaagent/build.gradle.kts

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+plugins {
+  id("otel.javaagent-instrumentation")
+}
+
+muzzle {
+  pass {
+    group.set("com.mchange")
+    module.set("c3p0")
+    versions.set("[0.9.2,)")
+    assertInverse.set(true)
+    // these versions have missing dependencies in maven central
+    skip("0.9.2-pre2-RELEASE", "0.9.2-pre3")
+  }
+}
+
+dependencies {
+  library("com.mchange:c3p0:0.9.2")
+
+  implementation(project(":instrumentation:c3p0-0.9:library"))
+
+  testImplementation(project(":instrumentation:c3p0-0.9:testing"))
+}

instrumentation/c3p0-0.9/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/c3p0/AbstractPoolBackedDataSourceInstrumentation.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.c3p0;
+
+import static io.opentelemetry.javaagent.instrumentation.c3p0.C3p0Singletons.telemetry;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+
+import com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource;
+import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
+import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
+import net.bytebuddy.asm.Advice;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.matcher.ElementMatcher;
+
+final class AbstractPoolBackedDataSourceInstrumentation implements TypeInstrumentation {
+
+  @Override
+  public ElementMatcher<TypeDescription> typeMatcher() {
+    return named("com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource");
+  }
+
+  @Override
+  public void transform(TypeTransformer transformer) {
+    transformer.applyAdviceToMethod(
+        named("resetPoolManager"), this.getClass().getName() + "$ResetPoolManagerAdvice");
+    transformer.applyAdviceToMethod(named("close"), this.getClass().getName() + "$CloseAdvice");
+  }
+
+  @SuppressWarnings("unused")
+  public static class ResetPoolManagerAdvice {
+
+    @Advice.OnMethodExit(suppress = Throwable.class)
+    public static void onExit(@Advice.This AbstractPoolBackedDataSource dataSource) {
+      telemetry().registerMetrics(dataSource);
+    }
+  }
+
+  @SuppressWarnings("unused")
+  public static class CloseAdvice {
+
+    @Advice.OnMethodExit(suppress = Throwable.class, onThrowable = Throwable.class)
+    public static void onExit(@Advice.This AbstractPoolBackedDataSource dataSource) {
+      telemetry().unregisterMetrics(dataSource);
+    }
+  }
+}

instrumentation/c3p0-0.9/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/c3p0/C3p0InstrumentationModule.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.c3p0;
+
+import com.google.auto.service.AutoService;
+import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
+import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
+import java.util.Collections;
+import java.util.List;
+
+@AutoService(InstrumentationModule.class)
+public class C3p0InstrumentationModule extends InstrumentationModule {
+
+  public C3p0InstrumentationModule() {
+    super("c3p0", "c3p0-0.9");
+  }
+
+  @Override
+  public List<TypeInstrumentation> typeInstrumentations() {
+    return Collections.singletonList(new AbstractPoolBackedDataSourceInstrumentation());
+  }
+}

instrumentation/c3p0-0.9/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/c3p0/C3p0Singletons.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.c3p0;
+
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.instrumentation.c3p0.C3p0Telemetry;
+
+public final class C3p0Singletons {
+
+  private static final C3p0Telemetry c3p0Telemetry =
+      C3p0Telemetry.create(GlobalOpenTelemetry.get());
+
+  public static C3p0Telemetry telemetry() {
+    return c3p0Telemetry;
+  }
+
+  private C3p0Singletons() {}
+}

instrumentation/c3p0-0.9/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/c3p0/C3p0InstrumentationTest.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.c3p0;
+
+import com.mchange.v2.c3p0.PooledDataSource;
+import io.opentelemetry.instrumentation.c3p0.AbstractC3p0InstrumentationTest;
+import io.opentelemetry.instrumentation.testing.junit.AgentInstrumentationExtension;
+import io.opentelemetry.instrumentation.testing.junit.InstrumentationExtension;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+public class C3p0InstrumentationTest extends AbstractC3p0InstrumentationTest {
+
+  @RegisterExtension
+  static final InstrumentationExtension testing = AgentInstrumentationExtension.create();
+
+  @Override
+  protected InstrumentationExtension testing() {
+    return testing;
+  }
+
+  @Override
+  protected void configure(PooledDataSource dataSource) {}
+
+  @Override
+  protected void shutdown(PooledDataSource dataSource) {}
+}

instrumentation/c3p0-0.9/library/README.md

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+# Manual Instrumentation for C3P0
+
+Provides OpenTelemetry instrumentation for [C3P0](https://www.mchange.com/projects/c3p0/).
+
+## Quickstart
+
+### Add these dependencies to your project:
+
+Replace `OPENTELEMETRY_VERSION` with the latest stable
+[release](https://mvnrepository.com/artifact/io.opentelemetry). `Minimum version: 1.15.0`
+
+For Maven, add to your `pom.xml` dependencies:
+
+```xml
+
+<dependencies>
+  <dependency>
+    <groupId>io.opentelemetry.instrumentation</groupId>
+    <artifactId>opentelemetry-c3p0-0.9</artifactId>
+    <version>OPENTELEMETRY_VERSION</version>
+  </dependency>
+</dependencies>
+```
+
+For Gradle, add to your dependencies:
+
+```groovy
+implementation("io.opentelemetry.instrumentation:opentelemetry-c3p0-0.9:OPENTELEMETRY_VERSION")
+```
+
+### Usage
+
+The instrumentation library allows registering `PooledDataSource` instances for
+collecting OpenTelemetry-based metrics.
+
+```java
+C3p0Telemetry c3p0Telemetry;
+
+void configure(OpenTelemetry openTelemetry, PooledDataSource dataSource) {
+  c3p0Telemetry = C3p0Telemetry.create(openTelemetry);
+  c3p0Telemetry.registerMetrics(dataSource);
+}
+
+void destroy(PooledDataSource dataSource) {
+  c3p0Telemetry.unregisterMetrics(dataSource);
+}
+```

instrumentation/c3p0-0.9/library/build.gradle.kts

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+plugins {
+  id("otel.library-instrumentation")
+  id("otel.nullaway-conventions")
+}
+
+dependencies {
+  library("com.mchange:c3p0:0.9.2")
+
+  testImplementation(project(":instrumentation:c3p0-0.9:testing"))
+}

instrumentation/c3p0-0.9/library/src/main/java/io/opentelemetry/instrumentation/c3p0/C3p0Telemetry.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.c3p0;
+
+import com.mchange.v2.c3p0.PooledDataSource;
+import io.opentelemetry.api.OpenTelemetry;
+
+public final class C3p0Telemetry {
+  /** Returns a new {@link C3p0Telemetry} configured with the given {@link OpenTelemetry}. */
+  public static C3p0Telemetry create(OpenTelemetry openTelemetry) {
+    return new C3p0Telemetry(openTelemetry);
+  }
+
+  private final OpenTelemetry openTelemetry;
+
+  private C3p0Telemetry(OpenTelemetry openTelemetry) {
+    this.openTelemetry = openTelemetry;
+  }
+
+  /** Start collecting metrics for given connection pool. */
+  public void registerMetrics(PooledDataSource dataSource) {
+    ConnectionPoolMetrics.registerMetrics(openTelemetry, dataSource);
+  }
+
+  /** Stop collecting metrics for given connection pool. */
+  public void unregisterMetrics(PooledDataSource dataSource) {
+    ConnectionPoolMetrics.unregisterMetrics(dataSource);
+  }
+}

instrumentation/c3p0-0.9/library/src/main/java/io/opentelemetry/instrumentation/c3p0/ConnectionPoolMetrics.java

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+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.c3p0;
+
+import com.mchange.v2.c3p0.PooledDataSource;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.metrics.ObservableLongUpDownCounter;
+import io.opentelemetry.instrumentation.api.metrics.db.DbConnectionPoolMetrics;
+import java.sql.SQLException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.LongSupplier;
+import javax.annotation.Nullable;
+
+final class ConnectionPoolMetrics {
+  private static final String INSTRUMENTATION_NAME = "io.opentelemetry.c3p0-0.9";
+
+  // a weak map does not make sense here because each Meter holds a reference to the dataSource
+  // PooledDataSource implements equals() & hashCode() in IdentityTokenResolvable,
+  // that's why we wrap it with IdentityDataSourceKey that uses identity comparison instead
+  private static final Map<IdentityDataSourceKey, List<ObservableLongUpDownCounter>>
+      dataSourceMetrics = new ConcurrentHashMap<>();
+
+  public static void registerMetrics(OpenTelemetry openTelemetry, PooledDataSource dataSource) {
+    dataSourceMetrics.compute(
+        new IdentityDataSourceKey(dataSource),
+        (key, existingCounters) ->
+            ConnectionPoolMetrics.createMeters(openTelemetry, key, existingCounters));
+  }
+
+  private static List<ObservableLongUpDownCounter> createMeters(
+      OpenTelemetry openTelemetry,
+      IdentityDataSourceKey key,
+      List<ObservableLongUpDownCounter> existingCounters) {
+    // remove old counters from the registry in case they were already there
+    removeMetersFromRegistry(existingCounters);
+
+    PooledDataSource dataSource = key.dataSource;
+
+    DbConnectionPoolMetrics metrics =
+        DbConnectionPoolMetrics.create(
+            openTelemetry, INSTRUMENTATION_NAME, dataSource.getDataSourceName());
+
+    return Arrays.asList(
+        metrics.usedConnections(wrapThrowingSupplier(dataSource::getNumBusyConnectionsDefaultUser)),
+        metrics.idleConnections(wrapThrowingSupplier(dataSource::getNumIdleConnectionsDefaultUser)),
+        metrics.pendingRequestsForConnection(
+            wrapThrowingSupplier(dataSource::getNumThreadsAwaitingCheckoutDefaultUser)));
+  }
+
+  public static void unregisterMetrics(PooledDataSource dataSource) {
+    List<ObservableLongUpDownCounter> meters =
+        dataSourceMetrics.remove(new IdentityDataSourceKey(dataSource));
+    removeMetersFromRegistry(meters);
+  }
+
+  private static void removeMetersFromRegistry(
+      @Nullable List<ObservableLongUpDownCounter> observableInstruments) {
+    if (observableInstruments != null) {
+      for (ObservableLongUpDownCounter observable : observableInstruments) {
+        observable.close();
+      }
+    }
+  }
+
+  /**
+   * A wrapper over {@link PooledDataSource} that implements identity comparison in its {@link
+   * #equals(Object)} and {@link #hashCode()} methods.
+   */
+  static final class IdentityDataSourceKey {
+    final PooledDataSource dataSource;
+
+    IdentityDataSourceKey(PooledDataSource dataSource) {
+      this.dataSource = dataSource;
+    }
+
+    @Override
+    @SuppressWarnings("ReferenceEquality")
+    public boolean equals(@Nullable Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (o == null || getClass() != o.getClass()) {
+        return false;
+      }
+      IdentityDataSourceKey that = (IdentityDataSourceKey) o;
+      return dataSource == that.dataSource;
+    }
+
+    @Override
+    public int hashCode() {
+      return System.identityHashCode(dataSource);
+    }
+
+    @Override
+    public String toString() {
+      return dataSource.toString();
+    }
+  }
+
+  static LongSupplier wrapThrowingSupplier(DataSourceIntSupplier supplier) {
+    return () -> {
+      try {
+        return supplier.getAsInt();
+      } catch (SQLException e) {
+        throw new IllegalStateException("Failed to get C3P0 datasource metric", e);
+      }
+    };
+  }
+
+  @FunctionalInterface
+  interface DataSourceIntSupplier {
+    int getAsInt() throws SQLException;
+  }
+
+  private ConnectionPoolMetrics() {}
+}