Add isRemote check for context propagation

src/OpenTelemetry/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+* `TracerProviderSDK` modified for spans with remote parent. For such spans
+  activity will be created irrespective of SamplingResult, to maintain context
+  propagation.
+  ([#3329](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3329))
+
 * Fix issue where a measurement would be dropped when recording it with a
   null-valued tag.
   ([#3325](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3325))

src/OpenTelemetry/Trace/TracerProviderSdk.cs

@@ -199,7 +199,7 @@ internal sealed class TracerProviderSdk : TracerProvider
             else if (sampler is AlwaysOffSampler)
             {
                 listener.Sample = (ref ActivityCreationOptions<ActivityContext> options) =>
-                    !Sdk.SuppressInstrumentation ? PropagateOrIgnoreData(options.Parent.TraceId) : ActivitySamplingResult.None;
+                    !Sdk.SuppressInstrumentation ? PropagateOrIgnoreData(options.Parent) : ActivitySamplingResult.None;
                 this.getRequestedDataAction = this.RunGetRequestedDataAlwaysOffSampler;
             }
             else
@@ -393,17 +393,17 @@ protected override void Dispose(bool disposing)
                 return activitySamplingResult;
             }
 
-            return PropagateOrIgnoreData(options.Parent.TraceId);
+            return PropagateOrIgnoreData(options.Parent);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static ActivitySamplingResult PropagateOrIgnoreData(ActivityTraceId traceId)
+        private static ActivitySamplingResult PropagateOrIgnoreData(in ActivityContext parentContext)
         {
-            var isRootSpan = traceId == default;
+            var isRootSpan = parentContext.TraceId == default;
 
-            // If it is the root span select PropagationData so the trace ID is preserved
+            // If it is the root span or the parent is remote select PropagationData so the trace ID is preserved
             // even if no activity of the trace is recorded (sampled per OpenTelemetry parlance).
-            return isRootSpan
+            return (isRootSpan || parentContext.IsRemote)
                 ? ActivitySamplingResult.PropagationData
                 : ActivitySamplingResult.None;
         }

test/OpenTelemetry.Tests/Trace/TracerProviderSdkTest.cs

@@ -222,7 +222,7 @@ public void TracerProviderSdkSamplerAttributesAreAppliedToActivity(SamplingDecis
             }
         }
 
-        [Fact(Skip = "https://github.com/open-telemetry/opentelemetry-dotnet/issues/3315")]
+        [Fact]
         public void TracerSdkSetsActivitySamplingResultAsPropagationWhenParentIsRemote()
         {
             var testSampler = new TestSampler();