fix: telemetry dropped by user callbacks and by validation is now counted in client reports

src/Sentry/Internal/DefaultSentryMetricEmitter.cs

@@ -27,12 +27,14 @@ private protected override void CaptureMetric<T>(SentryMetricType type, string n
     {
         if (!SentryMetric.IsSupported(typeof(T)))
         {
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
             _options.DiagnosticLogger?.LogWarning("{0} is unsupported type for Sentry Metrics. The only supported types are byte, short, int, long, float, and double.", typeof(T));
             return;
         }
 
         if (string.IsNullOrEmpty(name))
         {
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
             _options.DiagnosticLogger?.LogWarning("Name of metrics cannot be null or empty. Metric-Type: {0}; Value-Type: {1}", type.ToString(), typeof(T));
             return;
         }
@@ -46,12 +48,14 @@ private protected override void CaptureMetric<T>(SentryMetricType type, string n
     {
         if (!SentryMetric.IsSupported(typeof(T)))
         {
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
             _options.DiagnosticLogger?.LogWarning("{0} is unsupported type for Sentry Metrics. The only supported types are byte, short, int, long, float, and double.", typeof(T));
             return;
         }
 
         if (string.IsNullOrEmpty(name))
         {
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
             _options.DiagnosticLogger?.LogWarning("Name of metrics cannot be null or empty. Metric-Type: {0}; Value-Type: {1}", type.ToString(), typeof(T));
             return;
         }
@@ -76,15 +80,20 @@ private protected override void CaptureMetric<T>(SentryMetric<T> metric) where T
             }
             catch (Exception e)
             {
+                _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.TraceMetric);
                 _options.DiagnosticLogger?.LogError(e, "The BeforeSendMetric callback threw an exception. The Metric will be dropped.");
                 return;
             }
         }
 
-        if (configuredMetric is not null)
+        if (configuredMetric is null)
         {
-            _batchProcessor.Enqueue(configuredMetric);
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.TraceMetric);
+            _options.DiagnosticLogger?.LogInfo("Metric dropped by BeforeSendMetric callback.");
+            return;
         }
+
+        _batchProcessor.Enqueue(configuredMetric);
     }
 
     /// <inheritdoc />

src/Sentry/Internal/DefaultSentryStructuredLogger.cs

@@ -39,6 +39,7 @@ private protected override void CaptureLog(SentryLogLevel level, string template
             }
             catch (FormatException e)
             {
+                _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.LogItem);
                 _options.DiagnosticLogger?.LogError(e, "Template string does not match the provided argument. The Log will be dropped.");
                 return;
             }
@@ -70,6 +71,7 @@ private protected override void CaptureLog(SentryLogLevel level, string template
         }
         catch (Exception e)
         {
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.LogItem);
             _options.DiagnosticLogger?.LogError(e, "The configureLog callback threw an exception. The Log will be dropped.");
             return;
         }
@@ -93,15 +95,20 @@ protected internal override void CaptureLog(SentryLog log)
             }
             catch (Exception e)
             {
+                _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.LogItem);
                 _options.DiagnosticLogger?.LogError(e, "The BeforeSendLog callback threw an exception. The Log will be dropped.");
                 return;
             }
         }
 
-        if (configuredLog is not null)
+        if (configuredLog is null)
         {
-            _batchProcessor.Enqueue(configuredLog);
+            _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.LogItem);
+            _options.DiagnosticLogger?.LogInfo("Log dropped by BeforeSendLog callback.");
+            return;
         }
+
+        _batchProcessor.Enqueue(configuredLog);
     }
 
     /// <inheritdoc />

src/Sentry/Internal/DiscardReason.cs

@@ -4,9 +4,11 @@ namespace Sentry.Internal;
 {
     // See https://develop.sentry.dev/sdk/client-reports/ for list
     public static DiscardReason BeforeSend = new("before_send");
+    public static DiscardReason CallbackError = new("callback_error");
     public static DiscardReason BufferOverflow = new("buffer_overflow");
     public static DiscardReason CacheOverflow = new("cache_overflow");
     public static DiscardReason EventProcessor = new("event_processor");
+    public static DiscardReason Invalid = new("invalid");
     public static DiscardReason NetworkError = new("network_error");
     public static DiscardReason QueueOverflow = new("queue_overflow");
     public static DiscardReason SendError = new("send_error");

src/Sentry/Internal/SentryEventHelper.cs

@@ -17,7 +17,17 @@ internal static class SentryEventHelper
 
         foreach (var processor in processors)
         {
-            processedEvent = processor.DoProcessEvent(processedEvent, effectiveHint);
+            try
+            {
+                processedEvent = processor.DoProcessEvent(processedEvent, effectiveHint);
+            }
+            catch (Exception e)
+            {
+                options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, dataCategory);
+                options.LogError(e, "Event processor {0} threw an exception. The event will be dropped.", processor.GetType().Name);
+                return null;
+            }
+
             if (processedEvent == null)
             {
                 options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.EventProcessor, dataCategory);
@@ -94,7 +104,7 @@ internal static class SentryEventHelper
         }
         catch (Exception e)
         {
-            options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.Feedback);
+            options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.Feedback);
             options.LogError(e, "The BeforeSendFeedback callback threw an exception. The feedback will be dropped.");
             return null;
         }

src/Sentry/SentryClient.cs

@@ -212,7 +212,18 @@ public void CaptureTransaction(SentryTransaction transaction, Scope? scope, Sent
         var processedTransaction = transaction;
         foreach (var processor in scope.GetAllTransactionProcessors())
         {
-            processedTransaction = processor.DoProcessTransaction(transaction, hint);
+            try
+            {
+                processedTransaction = processor.DoProcessTransaction(transaction, hint);
+            }
+            catch (Exception e)
+            {
+                _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.Transaction);
+                _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.Span, spanCount);
+                _options.LogError(e, "Transaction processor {0} threw an exception. The transaction will be dropped.", processor.GetType().Name);
+                return;
+            }
+
             if (processedTransaction == null) // Rejected transaction
             {
                 _options.ClientReportRecorder.RecordDiscardedEvent(DiscardReason.EventProcessor, DataCategory.Transaction);

test/Sentry.Tests/SentryClientTests.cs

@@ -387,6 +387,23 @@ public void CaptureEvent_EventProcessor_RejectEvent_RecordsDiscard()
             .RecordDiscardedEvent(DiscardReason.EventProcessor, DataCategory.Error);
     }
 
+    [Fact]
+    public void CaptureEvent_EventProcessorThrows_DropsEventAndRecordsDiscard()
+    {
+        var processor = Substitute.For<ISentryEventProcessor>();
+        processor.Process(Arg.Any<SentryEvent>()).Throws(new InvalidOperationException());
+
+        _fixture.SentryOptions.AddEventProcessor(processor);
+
+        var sut = _fixture.GetSut();
+        var id = sut.CaptureEvent(new SentryEvent());
+
+        id.Should().Be(SentryId.Empty);
+        _fixture.BackgroundWorker.DidNotReceive().EnqueueEnvelope(Arg.Any<Envelope>());
+        _fixture.ClientReportRecorder.Received(1)
+            .RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.Error);
+    }
+
     [Fact]
     public void CaptureEvent_ExceptionFilter_RecordsDiscard()
     {
@@ -1126,7 +1143,7 @@ public void CaptureFeedback_BeforeSendFeedbackThrows_FeedbackDropped()
         result.Should().Be(CaptureFeedbackResult.DroppedByBeforeSendFeedback);
         id.Should().Be(SentryId.Empty);
         _ = sut.Worker.DidNotReceive().EnqueueEnvelope(Arg.Any<Envelope>());
-        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.Feedback);
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.Feedback);
     }
 
     [Fact]
@@ -1695,6 +1712,31 @@ public void CaptureTransaction_TransactionProcessorRejectsEvent_RecordDiscardedE
         _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(reason, DataCategory.Span, expectedDroppedSpanCount);
     }
 
+    [Fact]
+    public void CaptureTransaction_TransactionProcessorThrows_DropsTransactionAndRecordsDiscard()
+    {
+        // Arrange
+        var processor = Substitute.For<ISentryTransactionProcessorWithHint>();
+        processor.Process(Arg.Any<SentryTransaction>(), Arg.Any<SentryHint>()).Throws(new InvalidOperationException());
+        _fixture.SentryOptions.AddTransactionProcessor(processor);
+
+        var hub = Substitute.For<IHub>();
+        var transaction = new TransactionTracer(hub, "test name", "test operation");
+        transaction.StartChild("span1");
+        transaction.StartChild("span2");
+        transaction.EndTimestamp = DateTimeOffset.Now; // finished
+
+        // Act
+        _fixture.GetSut().CaptureTransaction(new SentryTransaction(transaction));
+
+        // Assert
+        _fixture.BackgroundWorker.DidNotReceive().EnqueueEnvelope(Arg.Any<Envelope>());
+        var reason = DiscardReason.CallbackError;
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(reason, DataCategory.Transaction);
+        var expectedDroppedSpanCount = transaction.Spans.Count + 1;
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(reason, DataCategory.Span, expectedDroppedSpanCount);
+    }
+
     [Fact]
     public void CaptureTransaction_BeforeSendTransaction_GetsHint()
     {

test/Sentry.Tests/SentryMetricEmitterTests.Types.cs

@@ -163,6 +163,7 @@ public void Emit_Decimal_DoesNotCaptureEnvelope(SentryMetricType type)
         var entry = _fixture.DiagnosticLogger.Dequeue();
         entry.Level.Should().Be(SentryLevel.Warning);
         entry.Message.Should().Be("{0} is unsupported type for Sentry Metrics. The only supported types are byte, short, int, long, float, and double.");
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
         entry.Exception.Should().BeNull();
         entry.Args.Should().BeEquivalentTo([typeof(decimal)]);
     }
@@ -183,6 +184,7 @@ public void Emit_Half_DoesNotCaptureEnvelope(SentryMetricType type)
         var entry = _fixture.DiagnosticLogger.Dequeue();
         entry.Level.Should().Be(SentryLevel.Warning);
         entry.Message.Should().Be("{0} is unsupported type for Sentry Metrics. The only supported types are byte, short, int, long, float, and double.");
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
         entry.Exception.Should().BeNull();
         entry.Args.Should().BeEquivalentTo([typeof(Half)]);
     }
@@ -203,6 +205,7 @@ public void Emit_Enum_DoesNotCaptureEnvelope(SentryMetricType type)
         var entry = _fixture.DiagnosticLogger.Dequeue();
         entry.Level.Should().Be(SentryLevel.Warning);
         entry.Message.Should().Be("{0} is unsupported type for Sentry Metrics. The only supported types are byte, short, int, long, float, and double.");
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
         entry.Exception.Should().BeNull();
         entry.Args.Should().BeEquivalentTo([typeof(StringComparison)]);
     }
@@ -222,6 +225,7 @@ public void Emit_Name_Null_DoesNotCaptureEnvelope(SentryMetricType type, string
         var entry = _fixture.DiagnosticLogger.Dequeue();
         entry.Level.Should().Be(SentryLevel.Warning);
         entry.Message.Should().Be("Name of metrics cannot be null or empty. Metric-Type: {0}; Value-Type: {1}");
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
         entry.Exception.Should().BeNull();
         entry.Args.Should().BeEquivalentTo<object>([arg0, arg1]);
     }
@@ -241,6 +245,7 @@ public void Emit_Name_Empty_DoesNotCaptureEnvelope(SentryMetricType type, string
         var entry = _fixture.DiagnosticLogger.Dequeue();
         entry.Level.Should().Be(SentryLevel.Warning);
         entry.Message.Should().Be("Name of metrics cannot be null or empty. Metric-Type: {0}; Value-Type: {1}");
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.Invalid, DataCategory.TraceMetric);
         entry.Exception.Should().BeNull();
         entry.Args.Should().BeEquivalentTo<object>([arg0, arg1]);
     }

test/Sentry.Tests/SentryMetricEmitterTests.Values.cs

@@ -131,6 +131,7 @@ private void AssertEmittedUnit(MeasurementUnit unit, string expected)
 
         captured.Should().NotBeNull();
         captured.Unit.Should().Be(expected);
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -148,6 +149,7 @@ public void Emit_Unit_MeasurementUnit_None()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().Be("none");
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -165,6 +167,7 @@ public void Emit_Unit_MeasurementUnit_Custom()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().Be("custom_unit");
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -182,6 +185,7 @@ public void Emit_Unit_MeasurementUnit_Empty()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().BeEmpty();
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -199,6 +203,7 @@ public void Emit_Unit_MeasurementUnit_Null()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().BeNull();
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -216,6 +221,7 @@ public void Emit_Unit_MeasurementUnit_Default()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().BeNull();
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -234,6 +240,7 @@ public void Emit_Unit_String_Custom()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().Be("custom_unit");
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -252,6 +259,7 @@ public void Emit_Unit_String_Empty()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().BeEmpty();
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [Fact]
@@ -270,6 +278,7 @@ public void Emit_Unit_String_Null()
 
         captured.Should().NotBeNull();
         captured.Unit.Should().BeNull();
+        _fixture.DiagnosticLogger.Dequeue().Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
     }
 
     [SuppressMessage("Performance", "CA1859:Use concrete types when possible for improved performance", Justification = "The generic SentryMetric type is internal. Testing via the public abstract base type.")]

test/Sentry.Tests/SentryMetricEmitterTests.cs

@@ -13,10 +13,12 @@ public Fixture()
         {
             DiagnosticLogger = new InMemoryDiagnosticLogger();
             Hub = Substitute.For<IHub>();
+            ClientReportRecorder = Substitute.For<IClientReportRecorder>();
             Options = new SentryOptions
             {
                 Debug = true,
                 DiagnosticLogger = DiagnosticLogger,
+                ClientReportRecorder = ClientReportRecorder,
             };
             Clock = new MockClock(new DateTimeOffset(2025, 04, 22, 14, 51, 00, 789, TimeSpan.FromHours(2)));
             BatchSize = 2;
@@ -39,6 +41,7 @@ public Fixture()
 
         public InMemoryDiagnosticLogger DiagnosticLogger { get; }
         public IHub Hub { get; }
+        public IClientReportRecorder ClientReportRecorder { get; }
         public SentryOptions Options { get; }
         public ISystemClock Clock { get; }
         public int BatchSize { get; set; }
@@ -137,6 +140,12 @@ public void Emit_WhenBeforeSendMetricReturnsNull_DoesNotCaptureEnvelope()
 
         _fixture.Hub.Received(0).CaptureEnvelope(Arg.Any<Envelope>());
         invocations.Should().Be(1);
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.BeforeSend, DataCategory.TraceMetric);
+        var entry = _fixture.DiagnosticLogger.Dequeue();
+        entry.Level.Should().Be(SentryLevel.Info);
+        entry.Message.Should().Be("Metric dropped by BeforeSendMetric callback.");
+        entry.Exception.Should().BeNull();
+        entry.Args.Should().BeEmpty();
     }
 
     [Fact]
@@ -153,6 +162,7 @@ public void Emit_InvalidBeforeSendMetric_DoesNotCaptureEnvelope()
         entry.Message.Should().Be("The BeforeSendMetric callback threw an exception. The Metric will be dropped.");
         entry.Exception.Should().BeOfType<InvalidOperationException>();
         entry.Args.Should().BeEmpty();
+        _fixture.ClientReportRecorder.Received(1).RecordDiscardedEvent(DiscardReason.CallbackError, DataCategory.TraceMetric);
     }
 
     [Fact]