Skip to content

stream: settle pending stream iter reads on return #63521

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
trivikr wants to merge 1 commit into
base: main
Choose a base branch
from
+35 −0
Draft

stream: settle pending stream iter reads on return #63521

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions lib/internal/streams/iter/broadcast.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,7 @@ class BroadcastImpl {

function detach() {
state.detached = true;
state.resolve?.({ __proto__: null, done: true, value: undefined });
state.resolve = null;
state.reject = null;
if (self.#deleteConsumer(state)) {
Expand Down
8 changes: 8 additions & 0 deletions lib/internal/streams/iter/push.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -423,6 +423,7 @@ class PushQueue {
if (this.#consumerState !== 'active') return;
this.#consumerState = 'returned';
this.#cleanup();
this.#resolvePendingReadsDone();
this.#rejectPendingWrites(
new ERR_INVALID_STATE.TypeError('Stream closed by consumer'));
// If closing, reject the pending end promise
Expand Down Expand Up @@ -526,6 +527,13 @@ class PushQueue {
}
}

#resolvePendingReadsDone() {
while (this.#pendingReads.length > 0) {
this.#pendingReads.shift().resolve(
{ __proto__: null, value: undefined, done: true });
Copy link
Copy Markdown
Member

@jasnell jasnell May 23, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
{ __proto__: null, value: undefined, done: true });
{ __proto__: null, done: true, value: undefined });

Super minor nit... just keeping the shape the same.

Copy link
Copy Markdown
Member Author

@trivikr trivikr May 24, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The value comes before done in rest of push.js.
And done comes before value in rest of broadcast.js.

I'll make the change in a separate PR after this one is merged. It can happen in parallel.

Copy link
Copy Markdown
Member Author

@trivikr trivikr May 24, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Do you have a specific preference for the order?

In lib/**/*.js source files, excluding tests, docs, and deps:

  • done before value: 30
  • value before done: 20

In Iteration protocols for MDN, done appears before value.

Copy link
Copy Markdown
Member Author

@trivikr trivikr May 24, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I submitted a PR to enforce done before value in iterator result object in #63526

}
}

#rejectPendingWrites(error) {
while (this.#pendingWrites.length > 0) {
this.#pendingWrites.shift().reject(error);
Expand Down
13 changes: 13 additions & 0 deletions test/parallel/test-stream-iter-broadcast-basic.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -161,6 +161,18 @@ async function testCancelWithReason() {
assert.strictEqual(result.message, 'cancelled');
}

async function testPendingNextSettlesAfterReturn() {
const { broadcast: bc } = broadcast();
const iter = bc.push()[Symbol.asyncIterator]();

const pendingNext = iter.next();
await iter.return();

const result = await pendingNext;
assert.strictEqual(result.done, true);
assert.strictEqual(result.value, undefined);
}

// =============================================================================
// Writer fail detaches consumers
// =============================================================================
Expand Down Expand Up @@ -254,6 +266,7 @@ Promise.all([
testCancelWithoutReason(),
testCancelWithReason(),
testCancelWithFalsyReason(),
testPendingNextSettlesAfterReturn(),
testFailDetachesConsumers(),
testWriterFailIdempotent(),
testLateJoinerSeesBufferedData(),
Expand Down
13 changes: 13 additions & 0 deletions test/parallel/test-stream-iter-push-basic.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,18 @@ async function testConsumerBreakWriteSyncReturnsFalse() {
assert.strictEqual(writer.desiredSize, null);
}

async function testPendingNextSettlesAfterReturn() {
const { readable } = push();
const iter = readable[Symbol.asyncIterator]();

const pendingNext = iter.next();
await iter.return();

const result = await pendingNext;
assert.strictEqual(result.done, true);
assert.strictEqual(result.value, undefined);
}

async function testPushWithTransforms() {
const upper = (chunks) => {
if (chunks === null) return null;
Expand Down Expand Up @@ -177,6 +189,7 @@ Promise.all([
testAbortSignal(),
testPreAbortedSignal(),
testConsumerBreakWriteSyncReturnsFalse(),
testPendingNextSettlesAfterReturn(),
testPushWithTransforms(),
testInvalidBackpressure(),
]).then(common.mustCall());
Loading