Only set activity custom property when sampling AllData

This optimization means we don't pay the extra allocation and cost unnecessarily unless someone is actually requesting all data from activities. See open-telemetry/opentelemetry-dotnet#1397
devlooped · Jul 13, 2023 · 1567989 · 1567989
1 parent 7f7cd7b
commit 1567989
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Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/src/Merq.Core/Telemetry.cs b/src/Merq.Core/Telemetry.cs
@@ -71,8 +71,11 @@ static Telemetry()
             ?.SetTag("messaging.protocol.name", type.Assembly.GetName().Name)
             ?.SetTag("messaging.protocol.version", type.Assembly.GetName().Version?.ToString() ?? "unknown");
 
-        if (property != null && value != null)
-            activity?.SetCustomProperty(property, value);
+        if (property != null && value != null &&
+            // Additional optimization so we don't incur allocation of activity custom props storage 
+            // unless someone is actually requesting the data. See https://github.com/open-telemetry/opentelemetry-dotnet/issues/1397 
+            activity?.IsAllDataRequested == true)
+            activity.SetCustomProperty(property, value);
 
         activity?.Start();
 

diff --git a/src/Merq.Tests/MessageBusSpec.cs b/src/Merq.Tests/MessageBusSpec.cs
@@ -478,7 +478,7 @@ public void when_executing_can_access_command_from_activity_started()
                 if (a.GetTagItem("messaging.destination.name") is "Merq.CommandWithResult")
                     activity = a;
             },
-            Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllData,
+            Sample = (ref ActivityCreationOptions<ActivityContext> _) => _.Source.Name == "Merq" ? ActivitySamplingResult.AllData : ActivitySamplingResult.None,
             ShouldListenTo = source => source.Name == "Merq",
         };
 
@@ -497,7 +497,7 @@ public void when_execute_throws_activity_has_error_status()
         using var listener = new ActivityListener
         {
             ActivityStarted = x => activity = x,
-            Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllData,
+            Sample = (ref ActivityCreationOptions<ActivityContext> _) => _.Source.Name == "Merq" ? ActivitySamplingResult.AllData : ActivitySamplingResult.None,
             ShouldListenTo = source => source.Name == "Merq",
         };