fix: Stopping the SDK from creating DynamicSamplingContext Exception

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - `Hints` now accept attachments provided as a file path via `AddAttachment` method ([#2585](https://github.com/getsentry/sentry-dotnet/pull/2585))
 
+### Fixes
+
+- Resolved an isse where the SDK would throw an exception while attempting to set the DynamicSamplingContext but the context exists already. ([#2592](https://github.com/getsentry/sentry-dotnet/pull/2592))
+
 ### Dependencies
 
 - Bump CLI from v2.20.5 to v2.20.6 ([#2590](https://github.com/getsentry/sentry-dotnet/pull/2590))

src/Sentry/Internal/Hub.cs

@@ -216,8 +216,7 @@ public BaggageHeader GetBaggage()
         }
 
         var propagationContext = ScopeManager.GetCurrent().Key.PropagationContext;
-        propagationContext.DynamicSamplingContext ??= propagationContext.CreateDynamicSamplingContext(_options);
-        return propagationContext.DynamicSamplingContext.ToBaggageHeader();
+        return propagationContext.GetOrCreateDynamicSamplingContext(_options).ToBaggageHeader();
     }
 
     public TransactionContext ContinueTrace(
@@ -352,9 +351,7 @@ private void ApplyTraceContextToEvent(SentryEvent evt, SentryPropagationContext
         evt.Contexts.Trace.TraceId = propagationContext.TraceId;
         evt.Contexts.Trace.SpanId = propagationContext.SpanId;
         evt.Contexts.Trace.ParentSpanId = propagationContext.ParentSpanId;
-
-        propagationContext.DynamicSamplingContext ??= propagationContext.CreateDynamicSamplingContext(_options);
-        evt.DynamicSamplingContext = propagationContext.DynamicSamplingContext;
+        evt.DynamicSamplingContext = propagationContext.GetOrCreateDynamicSamplingContext(_options);
     }
 
     public SentryId CaptureEvent(SentryEvent evt, Action<Scope> configureScope) =>

src/Sentry/Scope.cs

@@ -242,7 +242,7 @@ public Scope(SentryOptions? options)
     internal Scope(SentryOptions? options, SentryPropagationContext? propagationContext)
     {
         Options = options ?? new SentryOptions();
-        PropagationContext = propagationContext ?? new SentryPropagationContext();
+        PropagationContext = new SentryPropagationContext(propagationContext);
     }
 
     // For testing. Should explicitly require SentryOptions.

src/Sentry/SentryPropagationContext.cs

@@ -8,21 +8,17 @@ internal class SentryPropagationContext
     public SpanId SpanId { get; }
     public SpanId? ParentSpanId { get; }
 
-    private DynamicSamplingContext? _dynamicSamplingContext;
-    public DynamicSamplingContext? DynamicSamplingContext
+    internal DynamicSamplingContext? _dynamicSamplingContext;
+
+    public DynamicSamplingContext GetOrCreateDynamicSamplingContext(SentryOptions options)
     {
-        get => _dynamicSamplingContext;
-        set
+        if (_dynamicSamplingContext is null)
         {
-            if (_dynamicSamplingContext is null)
-            {
-                _dynamicSamplingContext = value;
-            }
-            else
-            {
-                throw new Exception("Attempted to set the DynamicSamplingContext but the context exists already.");
-            }
+            options.LogDebug("Creating the Dynamic Sampling Context from the Propagation Context");
+            _dynamicSamplingContext = this.CreateDynamicSamplingContext(options);
         }
+
+        return _dynamicSamplingContext;
     }
 
     internal SentryPropagationContext(
@@ -33,13 +29,19 @@ internal class SentryPropagationContext
         TraceId = traceId;
         SpanId = SpanId.Create();
         ParentSpanId = parentSpanId;
-        DynamicSamplingContext = dynamicSamplingContext;
+        _dynamicSamplingContext = dynamicSamplingContext;
     }
 
-    public SentryPropagationContext()
+    public SentryPropagationContext() : this(null)
+    { }
+
+    public SentryPropagationContext(SentryPropagationContext? other)
     {
-        TraceId = SentryId.Create();
-        SpanId = SpanId.Create();
+        TraceId = other?.TraceId ?? SentryId.Create();
+        SpanId = other?.SpanId ?? SpanId.Create();
+        ParentSpanId = other?.ParentSpanId;
+
+        _dynamicSamplingContext = other?._dynamicSamplingContext;
     }
 
     public static SentryPropagationContext CreateFromHeaders(IDiagnosticLogger? logger, SentryTraceHeader? traceHeader, BaggageHeader? baggageHeader)

test/Sentry.Tests/ScopeTests.cs

@@ -98,7 +98,8 @@ public void Clone_NewScope_IncludesPropagationContext()
 
         var clone = sut.Clone();
 
-        Assert.Same(propagationContext, clone.PropagationContext);
+        Assert.Equal(propagationContext.TraceId, clone.PropagationContext.TraceId);
+        Assert.Equal(propagationContext.SpanId, clone.PropagationContext.SpanId);
     }
 
     [Fact]

test/Sentry.Tests/SentryPropagationContextTests.cs

@@ -2,6 +2,43 @@ namespace Sentry.Tests;
 
 public class SentryPropagationContextTests
 {
+    [Fact]
+    public void CopyConstructor_CreatesCopy()
+    {
+        var original = new SentryPropagationContext();
+        original.GetOrCreateDynamicSamplingContext(new SentryOptions {Dsn = ValidDsn});
+
+        var copy = new SentryPropagationContext(original);
+
+        Assert.Equal(original.TraceId, copy.TraceId);
+        Assert.Equal(original.SpanId, copy.SpanId);
+        Assert.Equal(original._dynamicSamplingContext, copy._dynamicSamplingContext);
+    }
+
+    [Fact]
+    public void GetOrCreateDynamicSamplingContext_DynamicSamplingContextIsNull_CreatesDynamicSamplingContext()
+    {
+        var options = new SentryOptions { Dsn = ValidDsn };
+        var propagationContext = new SentryPropagationContext();
+
+        Assert.Null(propagationContext._dynamicSamplingContext); // Sanity check
+        _ = propagationContext.GetOrCreateDynamicSamplingContext(options);
+
+        Assert.NotNull(propagationContext._dynamicSamplingContext);
+    }
+
+    [Fact]
+    public void GetOrCreateDynamicSamplingContext_DynamicSamplingContextIsNotNull_ReturnsSameDynamicSamplingContext()
+    {
+        var options = new SentryOptions { Dsn = ValidDsn };
+        var propagationContext = new SentryPropagationContext();
+        var firstDynamicSamplingContext = propagationContext.GetOrCreateDynamicSamplingContext(options);
+
+        var secondDynamicSamplingContext = propagationContext.GetOrCreateDynamicSamplingContext(options);
+
+        Assert.Same(firstDynamicSamplingContext, secondDynamicSamplingContext);
+    }
+
     [Fact]
     public void CreateFromHeaders_TraceHeaderNullButBaggageExists_CreatesPropagationContextWithoutDynamicSamplingContext()
     {
@@ -15,7 +52,7 @@ public void CreateFromHeaders_TraceHeaderNullButBaggageExists_CreatesPropagation
 
         var propagationContext = SentryPropagationContext.CreateFromHeaders(null, null, baggageHeader);
 
-        Assert.Null(propagationContext.DynamicSamplingContext);
+        Assert.Null(propagationContext._dynamicSamplingContext);
     }
 
     [Fact]
@@ -32,7 +69,6 @@ public void CreateFromHeaders_BaggageHeaderNotNull_CreatesPropagationContextWith
 
         var propagationContext = SentryPropagationContext.CreateFromHeaders(null, traceHeader, baggageHeader);
 
-        Assert.NotNull(propagationContext.DynamicSamplingContext);
-        Assert.Equal(4, propagationContext.DynamicSamplingContext.Items.Count);
+        Assert.Equal(4, propagationContext.GetOrCreateDynamicSamplingContext(new SentryOptions()).Items.Count);
     }
 }