Unit tests

src/Sentry.AspNetCore/SentryTracingMiddleware.cs

@@ -146,7 +146,11 @@ public async Task InvokeAsync(HttpContext context)
         }
         finally
         {
-            if (transaction is not null)
+            if (transaction is UnsampledTransaction)
+            {
+                transaction.Finish();
+            }
+            else if (transaction is TransactionTracer tracer)
             {
                 // The Transaction name was altered during the pipeline execution,
                 // That could be done by user interference or by some Event Capture
@@ -183,15 +187,15 @@ public async Task InvokeAsync(HttpContext context)
                     if (!string.IsNullOrEmpty(customTransactionName))
                     {
                         transaction.Name = $"{method} {customTransactionName}";
-                        ((TransactionTracer)transaction).NameSource = TransactionNameSource.Custom;
+                        tracer.NameSource = TransactionNameSource.Custom;
                     }
                     else
                     {
                         // Finally, fallback to using the URL path.
                         // e.g. "GET /pets/1"
                         var path = context.Request.Path;
                         transaction.Name = $"{method} {path}";
-                        ((TransactionTracer)transaction).NameSource = TransactionNameSource.Url;
+                        tracer.NameSource = TransactionNameSource.Url;
                     }
                 }
 
@@ -200,7 +204,7 @@ public async Task InvokeAsync(HttpContext context)
                     transaction.Finish(status);
                 }
                 // Status code not yet changed to 500 but an exception does exist
-                // so lets avoid passing the misleading 200 down and close only with
+                // so let's avoid passing the misleading 200 down and close only with
                 // the exception instance that will be inferred as errored.
                 else if (status == SpanStatus.Ok)
                 {

src/Sentry.Azure.Functions.Worker/SentryFunctionsWorkerMiddleware.cs

@@ -92,7 +92,7 @@ private async Task<TransactionContext> StartOrContinueTraceAsync(FunctionContext
         if (requestData is null)
         {
             // not an HTTP trigger
-            return SentrySdk.ContinueTrace((SentryTraceHeader?)null, (BaggageHeader?)null, transactionName, Operation);
+            return _hub.ContinueTrace((SentryTraceHeader?)null, (BaggageHeader?)null, transactionName, Operation);
         }
 
         var httpMethod = requestData.Method.ToUpperInvariant();

src/Sentry/Internal/Hub.cs

@@ -136,6 +136,7 @@ internal ITransactionTracer StartTransaction(
             return NoOpTransaction.Instance;
         }
 
+        bool? isSampled = null;
         double? sampleRate = null;
         var sampleRand = dynamicSamplingContext?.Items.TryGetValue("sample_rand", out var dscsampleRand) ?? false
             ? double.Parse(dscsampleRand, NumberStyles.Float, CultureInfo.InvariantCulture)
@@ -155,17 +156,20 @@ internal ITransactionTracer StartTransaction(
             if (tracesSampler(samplingContext) is { } samplerSampleRate)
             {
                 sampleRate = samplerSampleRate;
+                // The TracesSampler trumps all other sampling decisions (even the trace header)
+                isSampled = SampleRandHelper.IsSampled(sampleRand, sampleRate.Value);
             }
         }
 
-        // If the sampling decision isn't made by a trace sampler then fallback to Random sampling
+        // If the sampling decision isn't made by a trace sampler we check the trace header first (from the context) or
+        // finally fallback to Random sampling if the decision has been made by no other means
         sampleRate ??= _options.TracesSampleRate ?? 0.0;
-        var isSampled = SampleRandHelper.IsSampled(sampleRand, sampleRate.Value);
+        isSampled ??= context.IsSampled ?? SampleRandHelper.IsSampled(sampleRand, sampleRate.Value);
 
         // Make sure there is a replayId (if available) on the provided DSC (if any).
         dynamicSamplingContext = dynamicSamplingContext?.WithReplayId(_replaySession);
 
-        if (!isSampled)
+        if (isSampled is false)
         {
             var unsampledTransaction = new UnsampledTransaction(this, context)
             {
@@ -181,7 +185,6 @@ internal ITransactionTracer StartTransaction(
 
         var transaction = new TransactionTracer(this, context)
         {
-            IsSampled = true,
             SampleRate = sampleRate,
             SampleRand = sampleRand,
             DynamicSamplingContext = dynamicSamplingContext // Default to the provided DSC

src/Sentry/Internal/NoOpSpan.cs

@@ -21,8 +21,8 @@ protected NoOpSpan()
     public IReadOnlyDictionary<string, object?> Extra => ImmutableDictionary<string, object?>.Empty;
     public IReadOnlyDictionary<string, object?> Data => ImmutableDictionary<string, object?>.Empty;
     public DateTimeOffset StartTimestamp => default;
-    public DateTimeOffset? EndTimestamp => default;
-    public bool IsFinished => default;
+    public DateTimeOffset? EndTimestamp => null;
+    public virtual bool IsFinished => false;
 
     public virtual string Operation
     {

src/Sentry/Internal/UnsampledTransaction.cs

@@ -27,10 +27,15 @@ public UnsampledTransaction(IHub hub, ITransactionContext context)
 
     internal DynamicSamplingContext? DynamicSamplingContext { get; set; }
 
+    private bool _isFinished;
+    public override bool IsFinished => _isFinished;
+
     public override IReadOnlyCollection<ISpan> Spans => _spans;
 
     public override SpanId SpanId => _context.SpanId;
+
     public override SentryId TraceId => _context.TraceId;
+
     public override bool? IsSampled => false;
 
     public double? SampleRate { get; set; }
@@ -53,8 +58,17 @@ public override void Finish()
     {
         _options?.LogDebug("Finishing unsampled transaction");
 
-        // Clear the transaction from the scope
-        _hub.ConfigureScope(scope => scope.ResetTransaction(this));
+        // Ensure the transaction is really cleared from the scope
+        // See: https://github.com/getsentry/sentry-dotnet/issues/4198
+        _isFinished = true;
+
+        // Clear the transaction from the scope and regenerate the Propagation Context, so new events don't have a
+        // trace context that is "older" than the transaction that just finished
+        _hub.ConfigureScope(scope =>
+        {
+            scope.ResetTransaction(this);
+            scope.SetPropagationContext(new SentryPropagationContext());
+        });
 
         // Record the discarded events
         var spanCount = Spans.Count + 1; // 1 for each span + 1 for the transaction itself
@@ -83,5 +97,7 @@ public override ISpan StartChild(string operation)
     private class UnsampledSpan(UnsampledTransaction transaction) : NoOpSpan
     {
         public override ISpan StartChild(string operation) => transaction.StartChild(operation);
+
+        public override bool? IsSampled => false;
     }
 }

src/Sentry/TransactionTracer.cs

@@ -85,15 +85,7 @@ public SpanStatus? Status
     }
 
     /// <inheritdoc />
-    public bool? IsSampled
-    {
-        get => Contexts.Trace.IsSampled;
-        internal set
-        {
-            Contexts.Trace.IsSampled = value;
-            SampleRate ??= value == null ? null : value.Value ? 1.0 : 0.0;
-        }
-    }
+    public bool? IsSampled => true; // Implicitly if we instantiate this class then the transaction is sampled in
 
     /// <summary>
     /// The sample rate used for this transaction.
@@ -234,6 +226,7 @@ internal TransactionTracer(IHub hub, string name, string operation, TransactionN
     /// </summary>
     internal TransactionTracer(IHub hub, ITransactionContext context, TimeSpan? idleTimeout = null)
     {
+        Debug.Assert(context.IsSampled ?? true, "context.IsSampled should always be true when creating a TransactionTracer");
         _hub = hub;
         _options = _hub.GetSentryOptions();
         Name = context.Name;
@@ -244,7 +237,6 @@ internal TransactionTracer(IHub hub, ITransactionContext context, TimeSpan? idle
         TraceId = context.TraceId;
         Description = context.Description;
         Status = context.Status;
-        IsSampled = context.IsSampled;
         StartTimestamp = _stopwatch.StartDateTimeOffset;
 
         if (context is TransactionContext transactionContext)

test/Sentry.AspNet.Tests/HttpContextExtensionsTests.cs

@@ -11,7 +11,8 @@ public void StartSentryTransaction_CreatesValidTransaction()
         using var _ = SentrySdk.UseHub(new Hub(
             new SentryOptions
             {
-                Dsn = ValidDsn
+                Dsn = ValidDsn,
+                TracesSampleRate = 1.0
             },
             Substitute.For<ISentryClient>()
         ));
@@ -57,7 +58,8 @@ public void FinishSentryTransaction_FinishesTransaction()
         using var _ = SentrySdk.UseHub(new Hub(
             new SentryOptions
             {
-                Dsn = ValidDsn
+                Dsn = ValidDsn,
+                TracesSampleRate = 1.0
             },
             Substitute.For<ISentryClient>()
         ));
@@ -81,6 +83,7 @@ public void StartSentryTransaction_SendDefaultPii_set_to_true_sets_cookies()
             new SentryOptions
             {
                 Dsn = ValidDsn,
+                TracesSampleRate = 1.0,
                 SendDefaultPii = true
             },
             Substitute.For<ISentryClient>()
@@ -102,6 +105,7 @@ public void StartSentryTransaction_SendDefaultPii_set_to_true_does_not_set_cooki
             new SentryOptions
             {
                 Dsn = ValidDsn,
+                TracesSampleRate = 1.0,
                 SendDefaultPii = true
             },
             Substitute.For<ISentryClient>()

test/Sentry.AspNetCore.Tests/SentryTracingMiddlewareTests.cs

@@ -68,7 +68,7 @@ public async Task Transaction_is_bound_on_the_scope_automatically()
 
         var sentryClient = Substitute.For<ISentryClient>();
 
-        var hub = new Hub(new SentryOptions { Dsn = ValidDsn }, sentryClient);
+        var hub = new Hub(new SentryOptions { Dsn = ValidDsn, TracesSampleRate = 1.0 }, sentryClient);
 
         var server = new TestServer(new WebHostBuilder()
             .UseDefaultServiceProvider(di => di.EnableValidation())
@@ -105,8 +105,10 @@ public async Task Transaction_is_bound_on_the_scope_automatically()
         transaction.NameSource.Should().Be(TransactionNameSource.Route);
     }
 
-    [Fact]
-    public async Task Transaction_is_started_automatically_from_incoming_trace_header()
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task Transaction_is_started_automatically_from_incoming_trace_header(bool isSampled)
     {
         // Arrange
         var sentryClient = Substitute.For<ISentryClient>();
@@ -133,27 +135,41 @@ public async Task Transaction_is_started_automatically_from_incoming_trace_heade
         var client = server.CreateClient();
 
         // Act
+        var sentryTraceHeader = isSampled
+            ? "75302ac48a024bde9a3b3734a82e36c8-1000000000000000-1"
+            : "75302ac48a024bde9a3b3734a82e36c8-1000000000000000-0";
+
         using var request = new HttpRequestMessage(HttpMethod.Get, "/person/13")
         {
             Headers =
             {
-                {"sentry-trace", "75302ac48a024bde9a3b3734a82e36c8-1000000000000000-0"}
+                {"sentry-trace", sentryTraceHeader}
             }
         };
 
         await client.SendAsync(request);
 
         // Assert
-        sentryClient.Received(1).CaptureTransaction(Arg.Is<SentryTransaction>(t =>
-            t.Name == "GET /person/{id}" &&
-            t.NameSource == TransactionNameSource.Route &&
-            t.TraceId == SentryId.Parse("75302ac48a024bde9a3b3734a82e36c8") &&
-            t.ParentSpanId == SpanId.Parse("1000000000000000") &&
-            t.IsSampled == false
-        ),
-        Arg.Any<Scope>(),
-        Arg.Any<SentryHint>()
-        );
+        if (isSampled)
+        {
+            sentryClient.Received(1).CaptureTransaction(Arg.Is<SentryTransaction>(t =>
+                    t.Name == "GET /person/{id}" &&
+                    t.NameSource == TransactionNameSource.Route &&
+                    t.TraceId == SentryId.Parse("75302ac48a024bde9a3b3734a82e36c8") &&
+                    t.ParentSpanId == SpanId.Parse("1000000000000000") &&
+                    t.IsSampled == true
+                ),
+                Arg.Any<Scope>(),
+                Arg.Any<SentryHint>()
+            );
+        }
+        else
+        {
+            sentryClient.DidNotReceive().CaptureTransaction(Arg.Any<SentryTransaction>(),
+                Arg.Any<Scope>(),
+                Arg.Any<SentryHint>()
+            );
+        }
     }
 
     [Fact]

test/Sentry.Azure.Functions.Worker.Tests/SentryFunctionsWorkerMiddlewareTests.cs

@@ -65,17 +65,19 @@ public async Task Original_exception_rethrown()
     [Fact]
     public async Task Transaction_PropertiesAreSet()
     {
+        // Arrange
         var functionContext = Substitute.For<FunctionContext>();
         var functionDefinition = Substitute.For<FunctionDefinition>();
         functionContext.FunctionDefinition.Returns(functionDefinition);
         functionDefinition.Name.Returns(nameof(HttpFunction));
 
         var sut = _fixture.GetSut();
 
+        // Act
         await sut.Invoke(functionContext, context => HttpFunction(null, context));
 
+        // Assert
         var transaction = _fixture.Transaction;
-
         transaction.Should().NotBeNull();
         transaction.Name.Should().Be(functionDefinition.Name);
         transaction.Operation.Should().Be("function");

test/Sentry.DiagnosticSource.Tests/Integration/SQLite/SentryDiagnosticListenerTests.cs

@@ -50,10 +50,7 @@ public Fixture()
 
         public ITransactionTracer StartTransaction(IHub hub, ITransactionContext context)
         {
-            var transaction = new TransactionTracer(hub, context)
-            {
-                IsSampled = true
-            };
+            var transaction = new TransactionTracer(hub, context);
             var (currentScope, _) = ScopeManager.GetCurrent();
             currentScope.Transaction = transaction;
             return transaction;