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Fix ensure ordered chunks not dropping controller #2167

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1egoman merged 4 commits into from
Oct 21, 2026
+114 −0
Merged

Fix ensure ordered chunks not dropping controller #2167

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480c709
fix: ensure text/byte stream controller(s) are dropped when the strea…
1egoman Oct 20, 2026
08dfcbe
fix: add tests to assert stream controllers are dropped from maps
1egoman Oct 20, 2026
323677b
fix: add changeset
1egoman Oct 20, 2026
27aa5b8
fix: add regression test for exact specific issue
1egoman Oct 20, 2026
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5 changes: 5 additions & 0 deletions .changeset/olive-cities-enjoy.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'livekit-client': patch
---

Fixes an issue where if a data stream runs into a terminal error, any packets delivered afterwards will be treated as if the stream doesn't exist (and not throw a sync error)
89 changes: 89 additions & 0 deletions src/room/data-stream/incoming/IncomingDataStreamManager.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1262,6 +1262,18 @@ describe('IncomingDataStreamManager', () => {

const reader = await readerPromise;
await expect(reader.readAll()).rejects.toThrow('Missing chunk(s)');

// The errored stream must be unregistered, so packets still in flight for it are dropped
// instead of throwing on a closed controller (#2166).
expect(() =>
manager.handleDataStreamPacket(
chunkPacket(streamId, 3, new Uint8Array([1])),
Encryption_Type.NONE,
),
).not.toThrow();
expect(() =>
manager.handleDataStreamPacket(trailerPacket(streamId), Encryption_Type.NONE),
).not.toThrow();
});

it('should error on a gap in chunk indices on an uncompressed text stream', async () => {
Expand Down Expand Up @@ -1296,6 +1308,18 @@ describe('IncomingDataStreamManager', () => {

const reader = await readerPromise;
await expect(reader.readAll()).rejects.toThrow('Missing chunk(s)');

// The errored stream must be unregistered, so packets still in flight for it are dropped
// instead of throwing on a closed controller (#2166).
expect(() =>
manager.handleDataStreamPacket(
chunkPacket(streamId, 3, new Uint8Array([1])),
Encryption_Type.NONE,
),
).not.toThrow();
expect(() =>
manager.handleDataStreamPacket(trailerPacket(streamId), Encryption_Type.NONE),
).not.toThrow();
});

it('should error on a gap in chunk indices on an uncompressed byte stream', async () => {
Expand Down Expand Up @@ -1329,6 +1353,18 @@ describe('IncomingDataStreamManager', () => {

const reader = await readerPromise;
await expect(reader.readAll()).rejects.toThrow('Missing chunk(s)');

// The errored stream must be unregistered, so packets still in flight for it are dropped
// instead of throwing on a closed controller (#2166).
expect(() =>
manager.handleDataStreamPacket(
chunkPacket(streamId, 3, new Uint8Array([1])),
Encryption_Type.NONE,
),
).not.toThrow();
expect(() =>
manager.handleDataStreamPacket(trailerPacket(streamId), Encryption_Type.NONE),
).not.toThrow();
});

it('should drop a duplicate chunk index on an uncompressed text stream and still decode', async () => {
Expand Down Expand Up @@ -1795,5 +1831,58 @@ describe('IncomingDataStreamManager', () => {
const reader = await readerPromise;
await expect(reader.readAll()).rejects.toThrow('Encryption type mismatch');
});

it('should treat packets for a stream that errored on a chunk index gap as an unknown stream (#2166)', async () => {
const manager = new IncomingDataStreamManager();
manager.setConnected(true);

const readers: Array<TextStreamReader> = [];
manager.registerTextStreamHandler('my-topic', (reader) => readers.push(reader));

const streamId = crypto.randomUUID();
manager.handleDataStreamPacket(
headerPacket(streamId, 'textHeader', { compression: DataStream_CompressionType.NONE }),
Encryption_Type.NONE,
);
manager.handleDataStreamPacket(
chunkPacket(streamId, 0, new TextEncoder().encode('first')),
Encryption_Type.NONE,
);
// Skip chunk index 1, which errors the stream.
manager.handleDataStreamPacket(
chunkPacket(streamId, 2, new TextEncoder().encode('third')),
Encryption_Type.NONE,
);
expect(readers).toHaveLength(1);
await expect(readers[0].readAll()).rejects.toThrow('Missing chunk(s)');

// Packets still in flight for the errored stream are dropped, just like packets for a stream
// that was never opened, rather than throwing on a closed controller.
expect(() =>
manager.handleDataStreamPacket(
chunkPacket(streamId, 3, new TextEncoder().encode('fourth')),
Encryption_Type.NONE,
),
).not.toThrow();
expect(() =>
manager.handleDataStreamPacket(trailerPacket(streamId), Encryption_Type.NONE),
).not.toThrow();
expect(readers).toHaveLength(1);

// No state is left behind for the stream id: a header reusing it opens a brand new stream
// instead of failing with `AlreadyOpened`, and that stream reads cleanly from chunk 0.
manager.handleDataStreamPacket(
headerPacket(streamId, 'textHeader', { compression: DataStream_CompressionType.NONE }),
Encryption_Type.NONE,
);
manager.handleDataStreamPacket(
chunkPacket(streamId, 0, new TextEncoder().encode('fresh stream')),
Encryption_Type.NONE,
);
manager.handleDataStreamPacket(trailerPacket(streamId), Encryption_Type.NONE);

expect(readers).toHaveLength(2);
expect(await readers[1].readAll()).toEqual('fresh stream');
});
});
});
20 changes: 20 additions & 0 deletions src/room/data-stream/incoming/IncomingDataStreamManager.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,16 @@ export default class IncomingDataStreamManager {
sendingParticipantIdentity: participantIdentity,
});
},
cancel: () => {
// The consumer side of the pipe chain errored (e.g. `ensureOrderedChunks` saw a gap) or
// was cancelled, which cancels this source stream. Unregister it so later chunks and the
// trailer for this stream are dropped rather than hitting a closed controller.
if (
this.byteStreamControllers.get(streamHeader.streamId)?.controller === streamController
) {
this.byteStreamControllers.delete(streamHeader.streamId);
}
},
});
streamHandlerCallback(
new ByteStreamReader(
Expand Down Expand Up @@ -349,6 +359,16 @@ export default class IncomingDataStreamManager {
sendingParticipantIdentity: participantIdentity,
});
},
cancel: () => {
// The consumer side of the pipe chain errored (e.g. `ensureOrderedChunks` saw a gap) or
// was cancelled, which cancels this source stream. Unregister it so later chunks and the
// trailer for this stream are dropped rather than hitting a closed controller.
if (
this.textStreamControllers.get(streamHeader.streamId)?.controller === streamController
) {
this.textStreamControllers.delete(streamHeader.streamId);
Comment on lines +362 to +369

@devin-ai-integration devin-ai-integration Bot Oct 20, 2026

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🟡 Aborted reads keep receiving chunks

When readAll({ signal }) aborts, cancel never runs because reader cleanup only releases the lock. Both stream controllers keep accepting chunks into an unread queue until the trailer arrives.

Learn more

The manager registers an incoming stream until its source ReadableStream is canceled or a trailer arrives. The new source cancel hook unregisters it when cancellation propagates through the pipe. However, TextStreamReader and ByteStreamReader only release their reader locks when an abort or premature iteration ends. Releasing a lock does not cancel the stream, so its source remains registered and continues buffering incoming packets despite the caller having stopped reading. The same omission affects both new cancellation hooks.

Example: A client aborts reader.readAll({ signal }) during a large text transfer. The promise rejects, but later chunks continue to enter the text stream's unread queue until a trailer arrives; the byte reader behaves the same way.

Recommended fix: On abort or early iteration exit, cancel the underlying reader before releasing its lock, and test that both text and byte controllers drop subsequent packets immediately. Preserve the existing error propagation for failed reads.

Devin Review

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@1egoman 1egoman Oct 20, 2026 •
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I think this is outside the scope of this fix, and I will make a follow up pull request fixing this: #2168

}
},
});
streamHandlerCallback(
new TextStreamReader(
Expand Down
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