[temporalio#1962] Add newCallbackExecutor to interceptors and override for OpenTracing

This change adds newCallbackExecutor to the OutboundInterceptor interface,
overriding the OpenTracing behavior. This allows the OpenTracing interceptor
to transfer any active trace/span from the point of creation to the point of
deferred execution, thus preserving the span within the callback.

Without this, spans become disjoint across Promise.thenCompose, due to the
nature of the deferring the execution of the .thenCompose to a callback thread.

Fixes temporalio#1962

Signed-off-by: Greg Haskins <greg@manetu.com>

Author: ghaskins

temporal-opentracing/src/main/java/io/temporal/opentracing/internal/OpenTracingWorkflowOutboundCallsInterceptor.java

@@ -30,13 +30,38 @@
 import io.temporal.workflow.Workflow;
 import io.temporal.workflow.WorkflowInfo;
 import io.temporal.workflow.unsafe.WorkflowUnsafe;
+import java.util.concurrent.Executor;
 
 public class OpenTracingWorkflowOutboundCallsInterceptor
     extends WorkflowOutboundCallsInterceptorBase {
   private final SpanFactory spanFactory;
   private final Tracer tracer;
   private final ContextAccessor contextAccessor;
 
+  private class SpanTransferringExecutor implements Executor {
+    private final Executor passthrough;
+    private final Span capturedSpan;
+
+    public SpanTransferringExecutor(Executor passthrough) {
+      this.passthrough = passthrough;
+      capturedSpan = tracer.scopeManager().activeSpan();
+    }
+
+    public void execute(Runnable r) {
+      Span activeSpan = tracer.scopeManager().activeSpan();
+
+      if (activeSpan == null && capturedSpan != null) {
+        // if there is no activeSpan AND we captured a span during construction,
+        // we should transfer it to the calling context as the new activespan
+        try (Scope ignored = tracer.scopeManager().activate(capturedSpan)) {
+          passthrough.execute(r);
+        }
+      } else {
+        passthrough.execute(r);
+      }
+    }
+  }
+
   public OpenTracingWorkflowOutboundCallsInterceptor(
       WorkflowOutboundCallsInterceptor next,
       OpenTracingOptions options,
@@ -178,6 +203,12 @@ public Object newChildThread(Runnable runnable, boolean detached, String name) {
     return super.newChildThread(wrappedRunnable, detached, name);
   }
 
+  @Override
+  public Executor newCallbackExecutor() {
+    Executor passthrough = super.newCallbackExecutor();
+    return new SpanTransferringExecutor(passthrough);
+  }
+
   private Tracer.SpanBuilder createActivityStartSpanBuilder(String activityName) {
     WorkflowInfo workflowInfo = Workflow.getInfo();
     return spanFactory.createActivityStartSpan(

temporal-opentracing/src/test/java/io/temporal/opentracing/CallbackContextTest.java

@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2022 Temporal Technologies, Inc. All Rights Reserved.
+ *
+ * Copyright (C) 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Modifications copyright (C) 2017 Uber Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this material except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.temporal.opentracing;
+
+import static org.junit.Assert.assertEquals;
+
+import io.opentracing.Scope;
+import io.opentracing.Span;
+import io.opentracing.mock.MockSpan;
+import io.opentracing.mock.MockTracer;
+import io.opentracing.util.ThreadLocalScopeManager;
+import io.temporal.activity.ActivityInterface;
+import io.temporal.activity.ActivityMethod;
+import io.temporal.activity.ActivityOptions;
+import io.temporal.client.WorkflowClient;
+import io.temporal.client.WorkflowClientOptions;
+import io.temporal.client.WorkflowOptions;
+import io.temporal.testing.internal.SDKTestWorkflowRule;
+import io.temporal.worker.WorkerFactoryOptions;
+import io.temporal.workflow.*;
+import java.time.Duration;
+import org.junit.After;
+import org.junit.Rule;
+import org.junit.Test;
+
+public class CallbackContextTest {
+
+  private static final MockTracer mockTracer =
+      new MockTracer(new ThreadLocalScopeManager(), MockTracer.Propagator.TEXT_MAP);
+
+  private final OpenTracingOptions OT_OPTIONS =
+      OpenTracingOptions.newBuilder().setTracer(mockTracer).build();
+
+  @Rule
+  public SDKTestWorkflowRule testWorkflowRule =
+      SDKTestWorkflowRule.newBuilder()
+          .setWorkflowClientOptions(
+              WorkflowClientOptions.newBuilder()
+                  .setInterceptors(new OpenTracingClientInterceptor(OT_OPTIONS))
+                  .validateAndBuildWithDefaults())
+          .setWorkerFactoryOptions(
+              WorkerFactoryOptions.newBuilder()
+                  .setWorkerInterceptors(new OpenTracingWorkerInterceptor(OT_OPTIONS))
+                  .validateAndBuildWithDefaults())
+          .setWorkflowTypes(WorkflowImpl.class)
+          .setActivityImplementations(new ActivityImpl())
+          .build();
+
+  @After
+  public void tearDown() {
+    mockTracer.reset();
+  }
+
+  @ActivityInterface
+  public interface TestActivity {
+    @ActivityMethod
+    boolean activity();
+  }
+
+  @WorkflowInterface
+  public interface TestWorkflow {
+    @WorkflowMethod
+    String workflow();
+  }
+
+  public static class ActivityImpl implements TestActivity {
+    @Override
+    public boolean activity() {
+      try {
+        Thread.sleep(1000);
+      } catch (InterruptedException e) {
+        throw new RuntimeException(e);
+      }
+      return true;
+    }
+  }
+
+  public static class WorkflowImpl implements TestWorkflow {
+    private final TestActivity activity =
+        Workflow.newActivityStub(
+            TestActivity.class,
+            ActivityOptions.newBuilder()
+                .setStartToCloseTimeout(Duration.ofMinutes(1))
+                .validateAndBuildWithDefaults());
+
+    @Override
+    public String workflow() {
+      return Async.function(activity::activity)
+          .thenCompose(
+              (r) -> {
+                Span activeSpan = mockTracer.activeSpan();
+                return Workflow.newPromise(
+                    activeSpan != null ? activeSpan.context().toTraceId() : "not-found");
+              })
+          .get();
+    }
+  }
+
+  @Test
+  public void testCallbackContext() {
+    MockSpan span = mockTracer.buildSpan("ClientFunction").start();
+
+    WorkflowClient client = testWorkflowRule.getWorkflowClient();
+    try (Scope scope = mockTracer.scopeManager().activate(span)) {
+      TestWorkflow workflow =
+          client.newWorkflowStub(
+              TestWorkflow.class,
+              WorkflowOptions.newBuilder()
+                  .setTaskQueue(testWorkflowRule.getTaskQueue())
+                  .validateBuildWithDefaults());
+      assertEquals(span.context().toTraceId(), workflow.workflow());
+    } finally {
+      span.finish();
+    }
+  }
+}

temporal-sdk/src/main/java/io/temporal/common/interceptors/WorkflowOutboundCallsInterceptor.java

@@ -31,6 +31,7 @@
 import java.lang.reflect.Type;
 import java.time.Duration;
 import java.util.*;
+import java.util.concurrent.Executor;
 import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -798,5 +799,17 @@ <R> R mutableSideEffect(
    */
   Object newChildThread(Runnable runnable, boolean detached, String name);
 
+  /**
+   * Intercepts the point where a new callback is being prepared for deferment and allows
+   * interceptors to provide a wrapped execution environment for running the callback at a later
+   * time.
+   *
+   * <p>The executor's execute() function _must_ fully execute the provided Runnable within the
+   * caller's thread or determinism guarantees could be violated.
+   *
+   * @return created Executor
+   */
+  Executor newCallbackExecutor();
+
   long currentTimeMillis();
 }

temporal-sdk/src/main/java/io/temporal/common/interceptors/WorkflowOutboundCallsInterceptorBase.java

@@ -30,6 +30,7 @@
 import java.util.Map;
 import java.util.Random;
 import java.util.UUID;
+import java.util.concurrent.Executor;
 import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 
@@ -184,6 +185,11 @@ public Object newChildThread(Runnable runnable, boolean detached, String name) {
     return next.newChildThread(runnable, detached, name);
   }
 
+  @Override
+  public Executor newCallbackExecutor() {
+    return next.newCallbackExecutor();
+  }
+
   @Override
   public long currentTimeMillis() {
     return next.currentTimeMillis();

temporal-sdk/src/main/java/io/temporal/internal/sync/CompletablePromiseImpl.java

@@ -29,6 +29,7 @@
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -40,6 +41,7 @@ class CompletablePromiseImpl<V> implements CompletablePromise<V> {
   private final List<Functions.Proc> handlers = new ArrayList<>();
   private final DeterministicRunnerImpl runner;
   private boolean registeredWithRunner;
+  private Executor callbackExecutor;
 
   @SuppressWarnings("unchecked")
   static Promise<Object> promiseAnyOf(Promise<?>[] promises) {
@@ -62,7 +64,10 @@ static <V> Promise<V> promiseAnyOf(Iterable<Promise<V>> promises) {
   }
 
   CompletablePromiseImpl() {
-    runner = DeterministicRunnerImpl.currentThreadInternal().getRunner();
+    WorkflowThread workflowThread = DeterministicRunnerImpl.currentThreadInternal();
+    runner = workflowThread.getRunner();
+    callbackExecutor =
+        workflowThread.getWorkflowContext().getWorkflowOutboundInterceptor().newCallbackExecutor();
   }
 
   @Override
@@ -275,9 +280,14 @@ private <U> Promise<U> then(Functions.Proc1<CompletablePromise<U>> proc) {
    * @return true if there were any handlers invoked
    */
   private boolean invokeHandlers() {
-    for (Functions.Proc handler : handlers) {
-      handler.apply();
-    }
+    // execute synchronously to this thread, but under the context established in the constructor
+    callbackExecutor.execute(
+        () -> {
+          for (Functions.Proc handler : handlers) {
+            handler.apply();
+          }
+        });
+
     return !handlers.isEmpty();
   }
 }

temporal-sdk/src/main/java/io/temporal/internal/sync/SyncWorkflowContext.java

@@ -78,6 +78,7 @@
 import java.time.Duration;
 import java.time.Instant;
 import java.util.*;
+import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.BiPredicate;
@@ -412,6 +413,12 @@ public WorkflowMetadata getWorkflowMetadata() {
     return workflowMetadata.build();
   }
 
+  private class DirectExecutor implements Executor {
+    public void execute(Runnable r) {
+      r.run();
+    }
+  }
+
   private class ActivityCallback {
     private final CompletablePromise<Optional<Payloads>> result = Workflow.newPromise();
 
@@ -1419,6 +1426,11 @@ public Object newChildThread(Runnable runnable, boolean detached, String name) {
     return runner.newWorkflowThread(runnable, detached, name);
   }
 
+  @Override
+  public Executor newCallbackExecutor() {
+    return new DirectExecutor();
+  }
+
   @Override
   public long currentTimeMillis() {
     return replayContext.currentTimeMillis();

temporal-testing/src/main/java/io/temporal/testing/TestActivityEnvironmentInternal.java

@@ -497,6 +497,11 @@ public Object newChildThread(Runnable runnable, boolean detached, String name) {
       throw new UnsupportedOperationException("not implemented");
     }
 
+    @Override
+    public Executor newCallbackExecutor() {
+      throw new UnsupportedOperationException("not implemented");
+    }
+
     @Override
     public long currentTimeMillis() {
       throw new UnsupportedOperationException("not implemented");

temporal-testing/src/main/java/io/temporal/testing/internal/TracingWorkerInterceptor.java

@@ -36,6 +36,7 @@
 import java.lang.reflect.Type;
 import java.time.Duration;
 import java.util.*;
+import java.util.concurrent.Executor;
 import java.util.function.BiPredicate;
 import java.util.function.Supplier;
 import javax.annotation.Nonnull;
@@ -433,6 +434,15 @@ public Object newChildThread(Runnable runnable, boolean detached, String name) {
       return next.newChildThread(runnable, detached, name);
     }
 
+    @Override
+    public Executor newCallbackExecutor() {
+      if (!WorkflowUnsafe.isReplaying()) {
+        trace.add("newCallbackExecutor ");
+      }
+
+      return next.newCallbackExecutor();
+    }
+
     @Override
     public long currentTimeMillis() {
       if (!WorkflowUnsafe.isReplaying()) {