Add instrumentation for RxJava 3

instrumentation/rxjava/rxjava-3.0/javaagent/rxjava-3.0-javaagent.gradle

@@ -0,0 +1,19 @@
+apply from: "$rootDir/gradle/instrumentation.gradle"
+
+muzzle {
+  pass {
+    group = "io.reactivex.rxjava3"
+    module = "rxjava"
+    versions = "[3.0.0,)"
+    assertInverse true
+  }
+}
+
+dependencies {
+  library group: 'io.reactivex.rxjava3', name: 'rxjava', version: "3.0.0"
+
+  implementation project(":instrumentation:rxjava:rxjava-3.0:library")
+
+  testImplementation deps.opentelemetryExtAnnotations
+  testImplementation project(':instrumentation:rxjava:rxjava-3.0:testing')
+}

instrumentation/rxjava/rxjava-3.0/javaagent/src/main/java/io/opentelemetry/instrumentation/rxjava3/RxJava3InstrumentationModule.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.rxjava3;
+
+import static net.bytebuddy.matcher.ElementMatchers.isMethod;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+
+import com.google.auto.service.AutoService;
+import io.opentelemetry.javaagent.tooling.InstrumentationModule;
+import io.opentelemetry.javaagent.tooling.TypeInstrumentation;
+import io.reactivex.rxjava3.plugins.RxJavaPlugins;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import net.bytebuddy.asm.Advice;
+import net.bytebuddy.description.method.MethodDescription;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.matcher.ElementMatcher;
+
+@AutoService(InstrumentationModule.class)
+public class RxJava3InstrumentationModule extends InstrumentationModule {
+
+  public RxJava3InstrumentationModule() {
+    super("rxjava3");
+  }
+
+  @Override
+  public List<TypeInstrumentation> typeInstrumentations() {
+    return Collections.singletonList(new PluginInstrumentation());
+  }
+
+  public static class PluginInstrumentation implements TypeInstrumentation {
+
+    @Override
+    public ElementMatcher<TypeDescription> typeMatcher() {
+      return named("io.reactivex.rxjava3.plugins.RxJavaPlugins");
+    }
+
+    @Override
+    public Map<? extends ElementMatcher<? super MethodDescription>, String> transformers() {
+      return Collections.singletonMap(
+          isMethod(), RxJava3InstrumentationModule.class.getName() + "$RxJavaPluginsAdvice");
+    }
+  }
+
+  public static class RxJavaPluginsAdvice {
+
+    // TODO(anuraaga): Replace with adding a type initializer to RxJavaPlugins
+    // https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/2685
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    public static void activateOncePerClassloader() {
+      TracingAssemblyActivation.activate(RxJavaPlugins.class);
+    }
+  }
+}

instrumentation/rxjava/rxjava-3.0/javaagent/src/main/java/io/opentelemetry/instrumentation/rxjava3/TracingAssemblyActivation.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.rxjava3;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public final class TracingAssemblyActivation {
+
+  private static final ClassValue<AtomicBoolean> activated =
+      new ClassValue<AtomicBoolean>() {
+        @Override
+        protected AtomicBoolean computeValue(Class<?> type) {
+          return new AtomicBoolean();
+        }
+      };
+
+  public static void activate(Class<?> clz) {
+    if (activated.get(clz).compareAndSet(false, true)) {
+      TracingAssembly.enable();
+    }
+  }
+
+  private TracingAssemblyActivation() {}
+}

instrumentation/rxjava/rxjava-3.0/javaagent/src/test/groovy/RxJava3SubscriptionTest.groovy

@@ -0,0 +1,11 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import io.opentelemetry.instrumentation.rxjava3.AbstractRxJava3SubscriptionTest
+import io.opentelemetry.instrumentation.test.AgentTestTrait
+
+class RxJava3SubscriptionTest extends AbstractRxJava3SubscriptionTest implements AgentTestTrait {
+
+}

instrumentation/rxjava/rxjava-3.0/javaagent/src/test/groovy/RxJava3Test.groovy

@@ -0,0 +1,10 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import io.opentelemetry.instrumentation.rxjava3.AbstractRxJava3Test
+import io.opentelemetry.instrumentation.test.AgentTestTrait
+
+class RxJava3Test extends AbstractRxJava3Test implements AgentTestTrait {
+}