Don't create handler activity when incoming message activity isn't set (

#6582) (#6586)
Particular · Nov 3, 2022 · 89fd67b · 89fd67b
1 parent 49d6733
commit 89fd67b
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Showing 2 changed files with 22 additions and 0 deletions.
diff --git a/src/NServiceBus.Core.Tests/OpenTelemetry/ActivityFactoryTests.cs b/src/NServiceBus.Core.Tests/OpenTelemetry/ActivityFactoryTests.cs
@@ -221,10 +221,23 @@ public void Should_set_activity_in_context()
 
     class StartHandlerActivity : ActivityFactoryTests
     {
+        [Test]
+        public void Should_not_start_activity_when_no_parent_activity_exists()
+        {
+            Type handlerType = typeof(StartHandlerActivity);
+            var activity = activityFactory.StartHandlerActivity(new MessageHandler((_, _, _) => Task.CompletedTask, handlerType), null);
+
+            Assert.IsNull(activity, "should not start handler activity when no parent activity exists");
+        }
+
         [Test]
         public void Should_set_handler_type_as_tag()
         {
             Type handlerType = typeof(StartHandlerActivity);
+
+            using var ambientActivity = new Activity("ambient activity");
+            ambientActivity.Start();
+
             var activity = activityFactory.StartHandlerActivity(new MessageHandler((_, _, _) => Task.CompletedTask, handlerType), null);
 
             Assert.IsNotNull(activity);
@@ -237,6 +250,9 @@ public void Should_set_saga_id_when_saga()
         {
             var sagaInstance = new ActiveSagaInstance(null, null, () => DateTimeOffset.UtcNow) { SagaId = Guid.NewGuid().ToString() };
 
+            using var ambientActivity = new Activity("ambient activity");
+            ambientActivity.Start();
+
             var activity = activityFactory.StartHandlerActivity(new MessageHandler((_, _, _) => Task.CompletedTask, typeof(StartHandlerActivity)), sagaInstance);
 
             Assert.IsNotNull(activity);

diff --git a/src/NServiceBus.Core/OpenTelemetry/Tracing/ActivityFactory.cs b/src/NServiceBus.Core/OpenTelemetry/Tracing/ActivityFactory.cs
@@ -70,6 +70,12 @@ public Activity StartOutgoingPipelineActivity(string activityName, string displa
 
     public Activity StartHandlerActivity(MessageHandler messageHandler, ActiveSagaInstance saga)
     {
+        if (Activity.Current == null)
+        {
+            // don't call StartActivity if we haven't started an activity from the incoming pipeline to avoid the handlers being sampled although the incoming message isn't.
+            return null;
+        }
+
         var activity = ActivitySources.Main.StartActivity(ActivityNames.InvokeHandlerActivityName);
 
         if (activity != null)