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Fix SSE client cancellation #9503

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Merged
michaelstaib merged 2 commits into from
Apr 3, 2026
+10 −5
Merged

Fix SSE client cancellation #9503

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7caa01d
Fix SSE client cancellation
michaelstaib Apr 2, 2026
b947c77
Update src/HotChocolate/AspNetCore/src/Transport.Http/Sse/SseReader.cs
michaelstaib Apr 3, 2026
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2 changes: 1 addition & 1 deletion src/HotChocolate/AspNetCore/src/Transport.Http/GraphQLHttpResponse.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,7 @@ public IAsyncEnumerable<OperationResult> ReadAsResultStreamAsync(CancellationTok

if (contentType?.MediaType.EqualsOrdinal(ContentType.EventStream) ?? false)
{
return new SseReader(_message);
return new SseReader(_message, cancellationToken);
}
Comment on lines 166 to 169
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Copilot AI Apr 2, 2026

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ReadAsResultStreamAsync now forwards the provided cancellationToken into SseReader, but SseReader currently treats a canceled PipeReader read as a normal end of stream (yield break) rather than propagating an OperationCanceledException. That makes cancellation behavior inconsistent with the non-SSE paths (which throw when the token is canceled) and makes it hard for callers to distinguish cancellation vs completion. Consider updating the SSE reader to throw when cancellation is requested (e.g., when the read is canceled) so this token has the expected observable effect.

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// The server supports the newer graphql-response+json media type and users are free
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11 changes: 8 additions & 3 deletions src/HotChocolate/AspNetCore/src/Transport.Http/Sse/SseReader.cs
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Expand Up @@ -6,7 +6,9 @@

namespace HotChocolate.Transport.Http;

internal class SseReader(HttpResponseMessage message) : IAsyncEnumerable<OperationResult>
internal class SseReader(
HttpResponseMessage message,
CancellationToken requestCancellationToken = default) : IAsyncEnumerable<OperationResult>
{
private static readonly StreamPipeReaderOptions s_options = new(
pool: MemoryPool<byte>.Shared,
Expand All @@ -18,8 +20,11 @@ internal class SseReader(HttpResponseMessage message) : IAsyncEnumerable<Operati
public async IAsyncEnumerator<OperationResult> GetAsyncEnumerator(
CancellationToken cancellationToken = default)
{
using var cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
await using var stream = await message.Content.ReadAsStreamAsync(cts.Token);
using var cts = CancellationTokenSource.CreateLinkedTokenSource(
requestCancellationToken,
cancellationToken);
await using var stream =
await message.Content.ReadAsStreamAsync(cts.Token).ConfigureAwait(false);
using var eventBuffer = new PooledArrayWriter();
var reader = PipeReader.Create(stream, s_options);

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2 changes: 1 addition & 1 deletion src/HotChocolate/AspNetCore/test/Transport.Http.Tests/GraphQLHttpClientTests.cs
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Expand Up @@ -713,7 +713,7 @@ mutation CreateReviewForEpisode(
var canceled = false;
try
{
await foreach (var result in subscriptionResponse.ReadAsResultStreamAsync().WithCancellation(cts.Token))
await foreach (var result in subscriptionResponse.ReadAsResultStreamAsync(cts.Token))
{
result.MatchInlineSnapshot(
"""
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