stream: drain pending writes before broadcast end#65334

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Merged
trivikr merged 1 commit into from
Aug 23, 2026
+258 −50
Merged

stream: drain pending writes before broadcast end #65334

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10 changes: 6 additions & 4 deletions doc/api/stream_iter.md
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down
126 changes: 92 additions & 34 deletions lib/internal/streams/iter/broadcast.js
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
PromiseReject,
PromiseResolve,
PromiseWithResolvers,
SafePromisePrototypeFinally,
SafePromiseRace,
SafeSet,
Symbol,
SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
if (!signal) return promise;

const { promise: aborted, reject } = PromiseWithResolvers();
const onAbort = () => reject(signal.reason);
signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
if (signal.aborted) onAbort();

return SafePromisePrototypeFinally(
SafePromiseRace([promise, aborted]),
() => signal.removeEventListener('abort', onAbort),
);
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
constructor(options) {
this.#options = options;
this[kOnBufferDrained] = null;
this[kOnEndDrained] = null;
}

setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
if (self.#deleteConsumer(state)) {
self.#tryTrimBuffer();
}
self.#notifyEndDrained();
}

return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
}
}
}
this.#notifyEndDrained();
}

[kAbort](reason) {
if (this.#ended || this.#error !== undefined) return;
if (this.#error !== undefined) return;
this.#error = reason;
this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

// Private methods

#notifyEndDrained() {
if (this.#ended && this.#consumers.size === 0) {
this[kOnEndDrained]?.();
}
}

#recomputeMinCursor() {
const { minCursor, minCursorConsumers } = getMinCursor(
this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
#broadcast;
#totalBytes = 0;
#closed;
#aborted = false;
#state = 'open';
#error;
#pendingEnd;
#pendingWrites = new RingBuffer();
#pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

this.#broadcast[kOnBufferDrained] = () => {
this.#resolvePendingWrites();
this.#resolvePendingDrains(true);
if (this.#state === 'open') {
this.#resolvePendingDrains(true);
}
};
this.#broadcast[kOnEndDrained] = () => this.#endDrained();
}

// The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
return promise;
}

#isClosed() {
return this.#closed !== undefined;
}

#isClosedOrAborted() {
return this.#isClosed() || this.#aborted;
}

get canWrite() {
return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
}

#canUseWriteFastPath(signal) {
return !signal && !this.#isClosed() && !this.#aborted &&
return !signal && this.#state === 'open' &&
this.#broadcast[kCanWrite]();
}

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
}

async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
throw this.#error;
}
if (this.#state !== 'open') {
throw new ERR_INVALID_STATE.TypeError('Writer is closed');
}

signal?.throwIfAborted();

const converted = convertChunks(chunks);

if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
}

writeSync(chunk) {
if (this.#isClosedOrAborted()) return false;
if (this.#state !== 'open') return false;
if (!this.#broadcast[kCanWrite]()) return false;
const converted =
toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

writevSync(chunks) {
validateArray(chunks, 'chunks');
if (this.#isClosedOrAborted()) return false;
if (this.#state !== 'open') return false;
if (!this.#broadcast[kCanWrite]()) return false;
const converted = convertChunks(chunks);
if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

end(options) {
const signal = getWriterSignal(options);
if (this.#state === 'errored') return PromiseReject(this.#error);
if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
if (signal?.aborted) return PromiseReject(signal.reason);

if (this.#isClosed()) return this.#closed;
this.#closed = PromiseResolve(this.#totalBytes);
this.#broadcast[kEnd]();
this.#resolvePendingDrains(false);
return this.#closed;
const endPromise = this.#getEndPromise();
if (this.#state === 'open') {
this.#state = 'closing';
this.#resolvePendingDrains(false);
this.#finishEndIfReady();
}

return raceEndWithSignal(endPromise, signal);
}

endSync() {
if (this.#closed) return this.#totalBytes;
this.#closed = PromiseResolve(this.#totalBytes);
this.#broadcast[kEnd]();
if (this.#state === 'closed') return this.#totalBytes;
if (this.#state === 'errored' || this.#state === 'closing') return -1;

this.#state = 'closing';
this.#resolvePendingDrains(false);
return this.#totalBytes;
this.#finishEndIfReady();
return this.#state === 'closed' ? this.#totalBytes : -1;
}

fail(reason) {
if (this.#isClosedOrAborted()) return;
this.#aborted = true;
this.#closed = PromiseResolve(this.#totalBytes);
if (this.#state === 'errored' || this.#state === 'closed') return;
this.#state = 'errored';
const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
this.#error = error;
this.#rejectPendingWrites(error);
this.#rejectPendingDrains(error);
this.#pendingEnd?.reject(error);
this.#broadcast[kAbort](error);
}

[SymbolAsyncDispose]() {
if (this.#state === 'closing') return this.#getEndPromise();
this.fail();
return PromiseResolve();
}
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
}

[kCancelWriter]() {
if (this.#isClosed()) return;
this.#closed = PromiseResolve(this.#totalBytes);
if (this.#state === 'closed' || this.#state === 'errored') return;
this.#state = 'closed';
this.#rejectPendingWrites(
lazyDOMException('Broadcast cancelled', 'AbortError'));
this.#resolvePendingDrains(false);
this.#pendingEnd?.resolve(this.#totalBytes);
}

#getEndPromise() {
this.#pendingEnd ??= PromiseWithResolvers();
return this.#pendingEnd.promise;
}

#finishEndIfReady() {
if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
this.#broadcast[kEnd]();
}
}

#endDrained() {
if (this.#state !== 'closing') return;
this.#state = 'closed';
this.#pendingEnd?.resolve(this.#totalBytes);
}

[kPendingWriteRemoved]() {
this.#finishEndIfReady();
}

/**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
break;
}
}
this.#finishEndIfReady();
}

#rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
if (idx !== -1) pendingWrites.removeAt(idx);
entry.chunk = null;
reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
if (idx !== -1) self[kPendingWriteRemoved]();
};
entry.resolve = function() {
signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
stream: drain pending writes before broadcast end#65334

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to your account

 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

 Merged


stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
stream: drain pending writes before broadcast end#65334

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 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

 Merged


stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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stream: drain pending writes before broadcast end#65334

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 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

 Merged


stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
stream: drain pending writes before broadcast end#65334

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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

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privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

 Merged


stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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trivikr
merged 1 commit into

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Aug 23, 2026

+258

−50

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stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
Loading
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
stream: drain pending writes before broadcast end#65334

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

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privacy statement. We’ll occasionally send you account related emails.

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to your account

 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

 Merged


stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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 Merged

trivikr
merged 1 commit into

from

Aug 23, 2026

+258

−50

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stream: drain pending writes before broadcast end
#65334
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10 changes: 6 additions & 4 deletions
doc/api/stream_iter.md

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -431,14 +431,16 @@ the write. Use [`ondrain()`][] to wait for capacity rather than polling.
 the pending `end()` call; it does not fail the writer itself.
* Returns: {Promise} Fulfills with the total number of bytes written.

Signal that no more data will be written.
Signals that no more data will be written and waits for buffered data to drain.

#### `writer.endSync()`

* Returns: {number} Total bytes written, or `-1` if the writer is not open.
* Returns: {number} Total bytes written, or `-1` if ending cannot complete
 synchronously.

Synchronous variant of `writer.end()`. Returns `-1` if the writer is already
closed or errored. Can be used as a try-fallback pattern:
Synchronous variant of `writer.end()`. A return value of `-1` means closing has
started but requires asynchronous draining. Use the try-fallback pattern to
await completion:

```cjs
const result = writer.endSync();
Expand Down

126 changes: 92 additions & 34 deletions
lib/internal/streams/iter/broadcast.js

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const {
 PromiseReject,
 PromiseResolve,
 PromiseWithResolvers,
 SafePromisePrototypeFinally,
 SafePromiseRace,
 SafeSet,
 Symbol,
 SymbolAsyncDispose,
Expand DownExpand Up@@ -77,6 +79,22 @@ const kEnd = Symbol('kEnd');
const kAbort = Symbol('kAbort');
const kCanWrite = Symbol('kCanWrite');
const kOnBufferDrained = Symbol('kOnBufferDrained');
const kOnEndDrained = Symbol('kOnEndDrained');
const kPendingWriteRemoved = Symbol('kPendingWriteRemoved');

function raceEndWithSignal(promise, signal) {
 if (!signal) return promise;

 const { promise: aborted, reject } = PromiseWithResolvers();
 const onAbort = () => reject(signal.reason);
 signal.addEventListener('abort', onAbort, { __proto__: null, once: true });
 if (signal.aborted) onAbort();

 return SafePromisePrototypeFinally(
 SafePromiseRace([promise, aborted]),
 () => signal.removeEventListener('abort', onAbort),
 );
}

// =============================================================================
// Broadcast Implementation
Expand All@@ -100,6 +118,7 @@ class BroadcastImpl {
 constructor(options) {
 this.#options = options;
 this[kOnBufferDrained] = null;
 this[kOnEndDrained] = null;
 }

 setWriter(writer) {
Expand DownExpand Up@@ -183,6 +202,7 @@ class BroadcastImpl {
 if (self.#deleteConsumer(state)) {
 self.#tryTrimBuffer();
 }
 self.#notifyEndDrained();
 }

 return {
Expand DownExpand Up@@ -358,10 +378,11 @@ class BroadcastImpl {
 }
 }
 }
 this.#notifyEndDrained();
 }

 [kAbort](reason) {
 if (this.#ended || this.#error !== undefined) return;
 if (this.#error !== undefined) return;
 this.#error = reason;
 this.#ended = true;

Expand DownExpand Up@@ -396,6 +417,12 @@ class BroadcastImpl {

 // Private methods

 #notifyEndDrained() {
 if (this.#ended && this.#consumers.size === 0) {
 this[kOnEndDrained]?.();
 }
 }

 #recomputeMinCursor() {
 const { minCursor, minCursorConsumers } = getMinCursor(
 this.#consumers, this.#bufferStart + this.#buffer.length);
Expand DownExpand Up@@ -516,8 +543,9 @@ let getBroadcastPendingWrites;
class BroadcastWriter {
 #broadcast;
 #totalBytes = 0;
 #closed;
 #aborted = false;
 #state = 'open';
 #error;
 #pendingEnd;
 #pendingWrites = new RingBuffer();
 #pendingDrains = [];

Expand All@@ -532,8 +560,11 @@ class BroadcastWriter {

 this.#broadcast[kOnBufferDrained] = () => {
 this.#resolvePendingWrites();
 this.#resolvePendingDrains(true);
 if (this.#state === 'open') {
 this.#resolvePendingDrains(true);
 }
 };
 this.#broadcast[kOnEndDrained] = () => this.#endDrained();
 }

 // The drainable protocol works with Stream.ondrain to provide a notification
Expand All@@ -547,20 +578,12 @@ class BroadcastWriter {
 return promise;
 }

 #isClosed() {
 return this.#closed !== undefined;
 }

 #isClosedOrAborted() {
 return this.#isClosed() || this.#aborted;
 }

 get canWrite() {
 return this.#isClosedOrAborted() ? null : this.#broadcast[kCanWrite]();
 return this.#state === 'open' ? this.#broadcast[kCanWrite]() : null;
 }

 #canUseWriteFastPath(signal) {
 return !signal && !this.#isClosed() && !this.#aborted &&
 return !signal && this.#state === 'open' &&
 this.#broadcast[kCanWrite]();
 }

Expand DownExpand Up@@ -592,13 +615,15 @@ class BroadcastWriter {
 }

 async #writevSlow(chunks, signal) {
// Check for pre-aborted
signal?.throwIfAborted();

 if (this.#isClosedOrAborted()) {
if (this.#state === 'errored') {
 throw this.#error;
 }
 if (this.#state !== 'open') {
 throw new ERR_INVALID_STATE.TypeError('Writer is closed');
 }

 signal?.throwIfAborted();

 const converted = convertChunks(chunks);

 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -624,7 +649,7 @@ class BroadcastWriter {
 }

 writeSync(chunk) {
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted =
 toUint8Array(chunk);
Expand All@@ -637,7 +662,7 @@ class BroadcastWriter {

 writevSync(chunks) {
 validateArray(chunks, 'chunks');
 if (this.#isClosedOrAborted()) return false;
 if (this.#state !== 'open') return false;
 if (!this.#broadcast[kCanWrite]()) return false;
 const converted = convertChunks(chunks);
 if (this.#broadcast[kWrite](converted)) {
Expand All@@ -651,34 +676,43 @@ class BroadcastWriter {

 end(options) {
 const signal = getWriterSignal(options);
 if (this.#state === 'errored') return PromiseReject(this.#error);
 if (this.#state === 'closed') return PromiseResolve(this.#totalBytes);
 if (signal?.aborted) return PromiseReject(signal.reason);

 if (this.#isClosed()) return this.#closed;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 this.#resolvePendingDrains(false);
 return this.#closed;
 const endPromise = this.#getEndPromise();
 if (this.#state === 'open') {
 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 this.#finishEndIfReady();
 }

 return raceEndWithSignal(endPromise, signal);
 }

 endSync() {
 if (this.#closed) return this.#totalBytes;
 this.#closed = PromiseResolve(this.#totalBytes);
 this.#broadcast[kEnd]();
 if (this.#state === 'closed') return this.#totalBytes;
 if (this.#state === 'errored' || this.#state === 'closing') return -1;

 this.#state = 'closing';
 this.#resolvePendingDrains(false);
 return this.#totalBytes;
 this.#finishEndIfReady();
 return this.#state === 'closed' ? this.#totalBytes : -1;
 }

 fail(reason) {
 if (this.#isClosedOrAborted()) return;
 this.#aborted = true;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'errored' || this.#state === 'closed') return;
 this.#state = 'errored';
 const error = reason ?? new ERR_INVALID_STATE.TypeError('Failed');
 this.#error = error;
 this.#rejectPendingWrites(error);
 this.#rejectPendingDrains(error);
 this.#pendingEnd?.reject(error);
 this.#broadcast[kAbort](error);
 }

 [SymbolAsyncDispose]() {
 if (this.#state === 'closing') return this.#getEndPromise();
 this.fail();
 return PromiseResolve();
 }
Expand All@@ -688,11 +722,33 @@ class BroadcastWriter {
 }

 [kCancelWriter]() {
 if (this.#isClosed()) return;
 this.#closed = PromiseResolve(this.#totalBytes);
 if (this.#state === 'closed' || this.#state === 'errored') return;
 this.#state = 'closed';
 this.#rejectPendingWrites(
 lazyDOMException('Broadcast cancelled', 'AbortError'));
 this.#resolvePendingDrains(false);
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 #getEndPromise() {
 this.#pendingEnd ??= PromiseWithResolvers();
 return this.#pendingEnd.promise;
 }

 #finishEndIfReady() {
 if (this.#state === 'closing' && this.#pendingWrites.length === 0) {
 this.#broadcast[kEnd]();
 }
 }

 #endDrained() {
 if (this.#state !== 'closing') return;
 this.#state = 'closed';
 this.#pendingEnd?.resolve(this.#totalBytes);
 }

 [kPendingWriteRemoved]() {
 this.#finishEndIfReady();
 }

 /**
Expand DownExpand Up@@ -724,6 +780,7 @@ class BroadcastWriter {
 break;
 }
 }
 this.#finishEndIfReady();
 }

 #rejectPendingWrites(error) {
Expand DownExpand Up@@ -756,6 +813,7 @@ function wireBroadcastWriteSignal(entry, signal, resolve, reject, self) {
 if (idx !== -1) pendingWrites.removeAt(idx);
 entry.chunk = null;
 reject(signal.reason ?? lazyDOMException('Aborted', 'AbortError'));
 if (idx !== -1) self[kPendingWriteRemoved]();
 };
 entry.resolve = function() {
 signal.removeEventListener('abort', onAbort);
Expand Down
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