fix: clear pending stream I/O tasks on cancellation#94
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richard-ramos
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vladopajic
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June 18, 2026 19:24
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
gmelodie
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Jun 18, 2026
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| proc clearPendingRead( | ||
| stream: Stream, doneFut: Future[int].Raising([CancelledError, StreamError]) | ||
| ) {.raises: [].} = | ||
| let task = stream.toRead.valueOr: | ||
| return | ||
| if task.doneFut != doneFut: | ||
| return | ||
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| stream.toRead = Opt.none(ReadTask) | ||
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| if stream.closedByEngine or stream.quicStream.isNil: | ||
| return | ||
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| if lsquic_stream_wantread(stream.quicStream, 0) == -1: | ||
| error "could not set stream wantread", | ||
| streamId = lsquic_stream_id(stream.quicStream) | ||
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| proc clearPendingWrite( | ||
| stream: Stream, doneFut: Future[void].Raising([CancelledError, StreamError]) | ||
| ) {.raises: [].} = | ||
| let task = stream.toWrite.valueOr: | ||
| return | ||
| if task.doneFut != doneFut: | ||
| return | ||
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| stream.toWrite = Opt.none(WriteTask) | ||
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| if stream.closedByEngine or stream.quicStream.isNil: | ||
| return | ||
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| if lsquic_stream_wantwrite(stream.quicStream, 0) == -1: | ||
| error "could not set stream wantwrite", | ||
| streamId = lsquic_stream_id(stream.quicStream) |
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Probably a nit but i feel like these two could be only one template
vladopajic
approved these changes
Jun 23, 2026
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Summary
Cancelling a pending
Stream.readOnceorStream.writeclears the registered stream task and disables the corresponding lsquic read/write interest. This prevents cancelled operations from leaving stale caller-owned buffers attached to future stream callbacks.Risk Assessment
The change is localized to stream read/write cancellation cleanup. The main risk is around stream close/reset timing while a pending operation is being cleared.