Don't create continuations when async propagation is off

dd-java-agent/instrumentation/java-concurrent/akka-testing/src/main/scala/AkkaActors.scala

@@ -33,21 +33,21 @@ class AkkaActors {
 
   @Trace
   def basicTell() : Unit = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     howdyGreeter ! WhoToGreet("Akka")
     howdyGreeter ! Greet
   }
 
   @Trace
   def basicAsk() : Unit = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     howdyGreeter ! WhoToGreet("Akka")
     howdyGreeter ? Greet
   }
 
   @Trace
   def basicForward() : Unit = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     helloGreeter ! WhoToGreet("Akka")
     helloGreeter ? Greet
   }

dd-java-agent/instrumentation/java-concurrent/scala-testing/src/test/scala/ScalaConcurrentTests.scala

@@ -13,7 +13,7 @@ class ScalaConcurrentTests {
     */
   @Trace
   def traceWithFutureAndCallbacks() : Integer = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     val goodFuture: Future[Integer] = Future {
       tracedChild("goodFuture")
       1
@@ -34,7 +34,7 @@ class ScalaConcurrentTests {
 
   @Trace
   def tracedAcrossThreadsWithNoTrace() :Integer = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     val goodFuture: Future[Integer] = Future {
       1
     }
@@ -54,7 +54,7 @@ class ScalaConcurrentTests {
     */
   @Trace
   def traceWithPromises() : Integer = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     val keptPromise = Promise[Boolean]()
     val brokenPromise = Promise[Boolean]()
     val afterPromise = keptPromise.future
@@ -87,7 +87,7 @@ class ScalaConcurrentTests {
     */
   @Trace
   def tracedWithFutureFirstCompletions() :Integer = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     val completedVal = Future.firstCompletedOf(
       List(
         Future {
@@ -111,7 +111,7 @@ class ScalaConcurrentTests {
     */
   @Trace
   def tracedTimeout(): Integer = {
-    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncLinking(true)
+    GlobalTracer.get().scopeManager().active().asInstanceOf[TraceScope].setAsyncPropagation(true)
     val f: Future[String] = Future {
       tracedChild("timeoutChild")
       while(true) {

dd-java-agent/instrumentation/java-concurrent/src/main/java/datadog/trace/instrumentation/java/concurrent/ExecutorInstrumentation.java

@@ -141,7 +141,7 @@ public final class ExecutorInstrumentation extends Instrumenter.Configurable {
         @Advice.Argument(value = 0, readOnly = false) Runnable task) {
       final Scope scope = GlobalTracer.get().scopeManager().active();
       if (scope instanceof TraceScope
-          && ((TraceScope) scope).isAsyncLinking()
+          && ((TraceScope) scope).isAsyncPropagating()
           && task != null
           && !(task instanceof DatadogWrapper)) {
         task = new RunnableWrapper(task, (TraceScope) scope);
@@ -165,7 +165,7 @@ public final class ExecutorInstrumentation extends Instrumenter.Configurable {
         @Advice.Argument(value = 0, readOnly = false) Callable task) {
       final Scope scope = GlobalTracer.get().scopeManager().active();
       if (scope instanceof TraceScope
-          && ((TraceScope) scope).isAsyncLinking()
+          && ((TraceScope) scope).isAsyncPropagating()
           && task != null
           && !(task instanceof DatadogWrapper)) {
         task = new CallableWrapper(task, (TraceScope) scope);
@@ -188,7 +188,7 @@ public final class ExecutorInstrumentation extends Instrumenter.Configurable {
     public static Collection<?> wrapJob(
         @Advice.Argument(value = 0, readOnly = false) Collection<? extends Callable<?>> tasks) {
       final Scope scope = GlobalTracer.get().scopeManager().active();
-      if (scope instanceof TraceScope && ((TraceScope) scope).isAsyncLinking()) {
+      if (scope instanceof TraceScope && ((TraceScope) scope).isAsyncPropagating()) {
         Collection<Callable<?>> wrappedTasks = new ArrayList<>(tasks.size());
         for (Callable task : tasks) {
           if (task != null) {
@@ -247,7 +247,7 @@ public final class ExecutorInstrumentation extends Instrumenter.Configurable {
     @Override
     public void run() {
       final TraceScope context = continuation.activate();
-      context.setAsyncLinking(true);
+      context.setAsyncPropagation(true);
       try {
         delegatee.run();
       } finally {
@@ -268,7 +268,7 @@ public final class ExecutorInstrumentation extends Instrumenter.Configurable {
     @Override
     public T call() throws Exception {
       final TraceScope context = continuation.activate();
-      context.setAsyncLinking(true);
+      context.setAsyncPropagation(true);
       try {
         return delegatee.call();
       } finally {

dd-java-agent/instrumentation/java-concurrent/src/test/groovy/ExecutorInstrumentationTest.groovy

@@ -50,7 +50,7 @@ class ExecutorInstrumentationTest extends AgentTestRunner {
       @Override
       @Trace(operationName = "parent")
       void run() {
-        ((ContinuableScope) GlobalTracer.get().scopeManager().active()).setAsyncLinking(true)
+        ((ContinuableScope) GlobalTracer.get().scopeManager().active()).setAsyncPropagation(true)
         // this child will have a span
         m.invoke(pool, new AsyncChild())
         // this child won't
@@ -95,7 +95,7 @@ class ExecutorInstrumentationTest extends AgentTestRunner {
       @Override
       @Trace(operationName = "parent")
       void run() {
-        ((ContinuableScope) GlobalTracer.get().scopeManager().active()).setAsyncLinking(true)
+        ((ContinuableScope) GlobalTracer.get().scopeManager().active()).setAsyncPropagation(true)
         try {
           for (int i = 0; i < 20; ++ i) {
             Future f = pool.submit((Callable)child)

dd-java-agent/instrumentation/play-2.4/src/main/java/datadog/trace/instrumentation/play/PlayInstrumentation.java

@@ -99,7 +99,7 @@ public final class PlayInstrumentation extends Instrumenter.Configurable {
       }
 
       if (GlobalTracer.get().scopeManager().active() instanceof TraceScope) {
-        ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncLinking(true);
+        ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncPropagation(true);
       }
       return scope;
     }
@@ -175,7 +175,7 @@ public final class PlayInstrumentation extends Instrumenter.Configurable {
     public Object apply(Throwable t, boolean isCheck) throws Exception {
       try {
         if (GlobalTracer.get().scopeManager().active() instanceof TraceScope) {
-          ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncLinking(false);
+          ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncPropagation(false);
         }
         onError(span, t);
       } catch (Throwable t2) {
@@ -202,7 +202,7 @@ public final class PlayInstrumentation extends Instrumenter.Configurable {
 
     public Result apply(Result result) {
       if (GlobalTracer.get().scopeManager().active() instanceof TraceScope) {
-        ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncLinking(false);
+        ((TraceScope) GlobalTracer.get().scopeManager().active()).setAsyncPropagation(false);
       }
       try {
         Tags.HTTP_STATUS.set(span, result.header().status());

dd-trace-api/src/main/java/datadog/trace/context/TraceScope.java

@@ -14,10 +14,14 @@ public interface TraceScope {
   void close();
 
   /** If true, this context will propagate across async boundaries. */
-  boolean isAsyncLinking();
+  boolean isAsyncPropagating();
 
-  /** Set context's async propagation value. */
+  /**
-  void setAsyncLinking(boolean value);
+   * Enable or disable async propagation. Async propagation is initially set to false.
+   *
+   * @param value The new propagation value. True == propagate. False == don't propagate.
+   */
+  void setAsyncPropagation(boolean value);
 
   /** Used to pass async context between workers. */
   interface Continuation {

dd-trace-ot/src/main/java/datadog/opentracing/scopemanager/ContinuableScope.java

@@ -28,7 +28,7 @@ public class ContinuableScope implements Scope, TraceScope {
   /** Continuation that created this scope. May be null. */
   private final Continuation continuation;
   /** Flag to propagate this scope across async boundaries. */
-  private final AtomicBoolean isAsyncLinking = new AtomicBoolean(false);
+  private final AtomicBoolean isAsyncPropagating = new AtomicBoolean(false);
 
   ContinuableScope(
       final ContextualScopeManager scopeManager,
@@ -73,23 +73,26 @@ public class ContinuableScope implements Scope, TraceScope {
   }
 
   @Override
-  public void setAsyncLinking(boolean value) {
+  public boolean isAsyncPropagating() {
-    isAsyncLinking.set(value);
+    return isAsyncPropagating.get();
   }
 
   @Override
-  public boolean isAsyncLinking() {
+  public void setAsyncPropagation(boolean value) {
-    return isAsyncLinking.get();
+    isAsyncPropagating.set(value);
   }
 
   /**
-   * The continuation returned should be closed after the associa
+   * The continuation returned must be closed or activated or the trace will not finish.
    *
-   * @param finishOnClose
+   * @return The new continuation, or null if this scope is not async propagating.
-   * @return
    */
   public Continuation capture() {
-    return new Continuation();
+    if (isAsyncPropagating()) {
+      return new Continuation();
+    } else {
+      return null;
+    }
   }
 
   public class Continuation implements Closeable, TraceScope.Continuation {

dd-trace-ot/src/test/groovy/datadog/opentracing/scopemanager/ScopeManagerTest.groovy

@@ -92,10 +92,30 @@ class ScopeManagerTest extends Specification {
     finishSpan << [true, false]
   }
 
+  def "ContinuableScope only creates continuations when propagation is set"() {
+    setup:
+    def builder = tracer.buildSpan("test")
+    def scope = (ContinuableScope) builder.startActive(true)
+    def continuation = scope.capture()
+
+    expect:
+    continuation == null
+
+    when:
+    scope.setAsyncPropagation(true)
+    continuation = scope.capture()
+    then:
+    continuation != null
+
+    cleanup:
+    continuation.close()
+  }
+
   def "ContinuableScope doesn't close if non-zero"() {
     setup:
     def builder = tracer.buildSpan("test")
     def scope = (ContinuableScope) builder.startActive(true)
+    scope.setAsyncPropagation(true)
     def continuation = scope.capture()
 
     expect:
@@ -149,6 +169,7 @@ class ScopeManagerTest extends Specification {
     def builder = tracer.buildSpan("test")
     def scope = (ContinuableScope) builder.startActive(false)
     def span = scope.span()
+    scope.setAsyncPropagation(true)
     def continuation = scope.capture()
     scope.close()
     span.finish()
@@ -186,6 +207,7 @@ class ScopeManagerTest extends Specification {
     def parentScope = tracer.buildSpan("parent").startActive(true)
     def parentSpan = parentScope.span()
     ContinuableScope childScope = (ContinuableScope) tracer.buildSpan("parent").startActive(true)
+    childScope.setAsyncPropagation(true)
     def childSpan = childScope.span()
 
     def continuation = childScope.capture()
@@ -209,6 +231,7 @@ class ScopeManagerTest extends Specification {
 
     when:
     def newScope = continuation.activate()
+    newScope.setAsyncPropagation(true)
     def newContinuation = newScope.capture()
 
     then:
@@ -236,6 +259,7 @@ class ScopeManagerTest extends Specification {
     def builder = tracer.buildSpan("test")
     def scope = (ContinuableScope) builder.startActive(false)
     def span = scope.span()
+    scope.setAsyncPropagation(true)
     def continuation = scope.capture()
     scope.close()
     span.finish()
@@ -313,6 +337,7 @@ class ScopeManagerTest extends Specification {
   def "ContinuableScope put in threadLocal after continuation activation"() {
     setup:
     ContinuableScope scope = (ContinuableScope) tracer.buildSpan("parent").startActive(true)
+    scope.setAsyncPropagation(true)
 
     expect:
     scopeManager.tlsScope.get() == scope