feat: Allow IScopeObserver to observe trace

src/Sentry/IScopeObserver.cs

@@ -29,4 +29,9 @@ public interface IScopeObserver
     /// Sets the user information.
     /// </summary>
     public void SetUser(SentryUser? user);
+
+    /// <summary>
+    /// Sets the current trace
+    /// </summary>
+    public void SetTrace(SentryId traceId, SpanId parentSpanId);
 }

src/Sentry/Internal/Hub.cs

@@ -255,7 +255,7 @@ public TransactionContext ContinueTrace(
         string? operation = null)
     {
         var propagationContext = SentryPropagationContext.CreateFromHeaders(_options.DiagnosticLogger, traceHeader, baggageHeader);
-        ConfigureScope(scope => scope.PropagationContext = propagationContext);
+        ConfigureScope(scope => scope.SetPropagationContext(propagationContext));
 
         return new TransactionContext(
             name: name ?? string.Empty,

src/Sentry/Internal/ScopeObserver.cs

@@ -84,4 +84,14 @@ public void SetUser(SentryUser? user)
     public abstract void SetUserImpl(SentryUser user);
 
     public abstract void UnsetUserImpl();
+
+    public void SetTrace(SentryId traceId, SpanId parentSpanId)
+    {
+        _options.DiagnosticLogger?.Log(
+            SentryLevel.Debug,"{0} Scope Sync - Setting Trace traceId:{1} parentSpanId:{2}", null,
+                _name, traceId, parentSpanId);
+        SetTraceImpl(traceId, parentSpanId);
+    }
+
+    public abstract void SetTraceImpl(SentryId traceId, SpanId parentSpanId);
 }

src/Sentry/InternalSentrySdk.cs

@@ -0,0 +1,14 @@
+namespace Sentry;
+
+/// <summary>
+/// Sentry SDK internal API methods meant for being used by the Sentry Unity SDK
+/// </summary>
+public static class InternalSentrySdk
+{
+    /// <summary>
+    /// Allows to set the trace
+    /// </summary>
+    public static void SetTrace(SentryId traceId, SpanId parentSpanId) =>
+        SentrySdk.CurrentHub.ConfigureScope(scope =>
+            scope.SetPropagationContext(new SentryPropagationContext(traceId, parentSpanId)));
+}

src/Sentry/Platforms/Android/AndroidScopeObserver.cs

@@ -99,4 +99,9 @@ public void SetUser(SentryUser? user)
             _innerObserver?.SetUser(user);
         }
     }
+
+    public void SetTrace(SentryId traceId, SpanId parentSpanId)
+    {
+        // TODO: This requires sentry-java 8.4.0
+    }
 }

src/Sentry/Platforms/Cocoa/CocoaScopeObserver.cs

@@ -107,4 +107,9 @@ public void SetUser(SentryUser? user)
             _innerObserver?.SetUser(user);
         }
     }
+
+    public void SetTrace(SentryId traceId, SpanId parentSpanId)
+    {
+        // TODO: Missing corresponding functionality on the Cocoa SDK
+    }
 }

src/Sentry/Platforms/Native/CFunctions.cs

@@ -241,6 +241,9 @@ internal static string GetCacheDirectory(SentryOptions options)
     [DllImport("sentry-native")]
     internal static extern void sentry_remove_extra(string key);
 
+    [DllImport("sentry-native")]
+    internal static extern void sentry_set_trace(string traceId, string parentSpanId);
+
     internal static Dictionary<long, DebugImage> LoadDebugImages(IDiagnosticLogger? logger)
     {
         // It only makes sense to load them once because they're cached on the native side anyway. We could force

src/Sentry/Platforms/Native/NativeScopeObserver.cs

@@ -40,6 +40,9 @@ public override void SetUserImpl(SentryUser user)
 
     public override void UnsetUserImpl() => C.sentry_remove_user();
 
+    public override void SetTraceImpl(SentryId traceId, SpanId parentSpanId) =>
+        C.sentry_set_trace(traceId.ToString(), parentSpanId.ToString());
+
     private static string GetTimestamp(DateTimeOffset timestamp) =>
         // "o": Using ISO 8601 to make sure the timestamp makes it to the bridge correctly.
         // https://docs.microsoft.com/en-gb/dotnet/standard/base-types/standard-date-and-time-format-strings#Roundtrip

src/Sentry/Scope.cs

@@ -233,7 +233,7 @@ public ITransactionTracer? Transaction
         }
     }
 
-    internal SentryPropagationContext PropagationContext { get; set; }
+    internal SentryPropagationContext PropagationContext { get; private set; }
 
     internal SessionUpdate? SessionUpdate { get; set; }
 
@@ -376,6 +376,15 @@ public void UnsetTag(string key)
     /// </summary>
     public void AddAttachment(SentryAttachment attachment) => _attachments.Add(attachment);
 
+    internal void SetPropagationContext(SentryPropagationContext propagationContext)
+    {
+        PropagationContext = propagationContext;
+        if (Options.EnableScopeSync)
+        {
+            Options.ScopeObserver?.SetTrace(propagationContext.TraceId, propagationContext.SpanId);
+        }
+    }
+
     /// <summary>
     /// Resets all the properties and collections within the scope to their default values.
     /// </summary>

test/Sentry.Tests/HubTests.cs

@@ -1013,7 +1013,7 @@ public void GetTraceHeader_NoSpanActive_ReturnsHeaderFromPropagationContext()
         var propagationContext = new SentryPropagationContext(
             SentryId.Parse("75302ac48a024bde9a3b3734a82e36c8"),
             SpanId.Parse("2000000000000000"));
-        hub.ConfigureScope(scope => scope.PropagationContext = propagationContext);
+        hub.ConfigureScope(scope => scope.SetPropagationContext(propagationContext));
 
         // Act
         var header = hub.GetTraceHeader();
@@ -1052,7 +1052,7 @@ public void GetBaggage_NoSpanActive_ReturnsBaggageFromPropagationContext()
         var hub = _fixture.GetSut();
         var propagationContext = new SentryPropagationContext(
             SentryId.Parse("43365712692146d08ee11a729dfbcaca"), SpanId.Parse("1000000000000000"));
-        hub.ConfigureScope(scope => scope.PropagationContext = propagationContext);
+        hub.ConfigureScope(scope => scope.SetPropagationContext(propagationContext));
 
         // Act
         var baggage = hub.GetBaggage();
@@ -1069,7 +1069,7 @@ public void ContinueTrace_SetsPropagationContextAndReturnsTransactionContext()
         var hub = _fixture.GetSut();
         var propagationContext = new SentryPropagationContext(
             SentryId.Parse("43365712692146d08ee11a729dfbcaca"), SpanId.Parse("1000000000000000"));
-        hub.ConfigureScope(scope => scope.PropagationContext = propagationContext);
+        hub.ConfigureScope(scope => scope.SetPropagationContext(propagationContext));
 
         var traceHeader = new SentryTraceHeader(SentryId.Parse("5bd5f6d346b442dd9177dce9302fd737"),
             SpanId.Parse("2000000000000000"), null);
@@ -1104,7 +1104,7 @@ public void ContinueTrace_ReceivesHeadersAsStrings_SetsPropagationContextAndRetu
         var hub = _fixture.GetSut();
         var propagationContext = new SentryPropagationContext(
             SentryId.Parse("43365712692146d08ee11a729dfbcaca"), SpanId.Parse("1000000000000000"));
-        hub.ConfigureScope(scope => scope.PropagationContext = propagationContext);
+        hub.ConfigureScope(scope => scope.SetPropagationContext(propagationContext));
         var traceHeader = "5bd5f6d346b442dd9177dce9302fd737-2000000000000000";
         var baggageHeader = "sentry-trace_id=5bd5f6d346b442dd9177dce9302fd737, sentry-public_key=49d0f7386ad645858ae85020e393bef3, sentry-sample_rate=1.0";
 

test/Sentry.Tests/ScopeTests.cs

@@ -633,6 +633,31 @@ public void SetTag_NullValue_DoesNotThrowArgumentNullException()
 
         Assert.Null(exception);
     }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public void SetPropagationContext_ObserverExist_ObserverSetsTraceIfEnabled(bool enableScopeSync)
+    {
+        // Arrange
+        var observer = Substitute.For<IScopeObserver>();
+        var scope = new Scope(new SentryOptions
+        {
+            ScopeObserver = observer,
+            EnableScopeSync = enableScopeSync
+        });
+        var propagationContext = new SentryPropagationContext();
+        var expectedTraceId = propagationContext.TraceId;
+        var expectedSpanId = propagationContext.SpanId;
+        var expectedCount = enableScopeSync ? 1 : 0;
+
+        // Act
+        scope.SetPropagationContext(propagationContext);
+
+        // Assert
+        scope.PropagationContext.Should().Be(propagationContext);
+        observer.Received(expectedCount).SetTrace(Arg.Is(expectedTraceId), Arg.Is(expectedSpanId));
+    }
 }
 
 public static class ScopeTestExtensions