feat(streams): ReadableStream.read min option (#20849)

ext/web/06_streams.js

@@ -79,6 +79,7 @@ const {
  TypedArrayPrototypeGetBuffer,
  TypedArrayPrototypeGetByteLength,
  TypedArrayPrototypeGetByteOffset,
+ TypedArrayPrototypeGetLength,
  TypedArrayPrototypeGetSymbolToStringTag,
  TypedArrayPrototypeSet,
  TypedArrayPrototypeSlice,
@@ -1303,7 +1304,9 @@ function readableByteStreamControllerClose(controller) {
  }
  if (controller[_pendingPullIntos].length !== 0) {
  const firstPendingPullInto = controller[_pendingPullIntos][0];
- if (firstPendingPullInto.bytesFilled > 0) {
+ if (
+ firstPendingPullInto.bytesFilled % firstPendingPullInto.elementSize !== 0
+ ) {
  const e = new TypeError(
  "Insufficient bytes to fill elements in the given buffer",
  );
@@ -1847,10 +1850,11 @@ function readableStreamDefaultcontrollerShouldCallPull(controller) {
 /**
  * @param {ReadableStreamBYOBReader} reader
  * @param {ArrayBufferView} view
+ * @param {number} min
  * @param {ReadIntoRequest} readIntoRequest
  * @returns {void}
  */
-function readableStreamBYOBReaderRead(reader, view, readIntoRequest) {
+function readableStreamBYOBReaderRead(reader, view, min, readIntoRequest) {
  const stream = reader[_stream];
  assert(stream);
  stream[_disturbed] = true;
@@ -1860,6 +1864,7 @@ function readableStreamBYOBReaderRead(reader, view, readIntoRequest) {
  readableByteStreamControllerPullInto(
  stream[_controller],
  view,
+ min,
  readIntoRequest,
  );
  }
@@ -1935,12 +1940,14 @@ function readableByteStreamControllerProcessReadRequestsUsingQueue(
 /**
  * @param {ReadableByteStreamController} controller
  * @param {ArrayBufferView} view
+ * @param {number} min
  * @param {ReadIntoRequest} readIntoRequest
  * @returns {void}
  */
 function readableByteStreamControllerPullInto(
  controller,
  view,
+ min,
  readIntoRequest,
 ) {
  const stream = controller[_stream];
@@ -2010,6 +2017,10 @@ function readableByteStreamControllerPullInto(
  );
  }
 
+ const minimumFill = min * elementSize;
+ assert(minimumFill >= 0 && minimumFill <= byteLength);
+ assert(minimumFill % elementSize === 0);
+
  try {
  buffer = transferArrayBuffer(buffer);
  } catch (e) {
@@ -2024,6 +2035,7 @@ function readableByteStreamControllerPullInto(
  byteOffset,
  byteLength,
  bytesFilled: 0,
+ minimumFill,
  elementSize,
  viewConstructor: ctor,
  readerType: "byob",
@@ -2139,7 +2151,7 @@ function readableByteStreamControllerRespondInReadableState(
  );
  return;
  }
- if (pullIntoDescriptor.bytesFilled < pullIntoDescriptor.elementSize) {
+ if (pullIntoDescriptor.bytesFilled < pullIntoDescriptor.minimumFill) {
  return;
  }
  readableByteStreamControllerShiftPendingPullInto(controller);
@@ -2219,7 +2231,7 @@ function readableByteStreamControllerRespondInClosedState(
  controller,
  firstDescriptor,
 ) {
- assert(firstDescriptor.bytesFilled === 0);
+ assert(firstDescriptor.bytesFilled % firstDescriptor.elementSize === 0);
  if (firstDescriptor.readerType === "none") {
  readableByteStreamControllerShiftPendingPullInto(controller);
  }
@@ -2249,7 +2261,9 @@ function readableByteStreamControllerCommitPullIntoDescriptor(
  assert(pullIntoDescriptor.readerType !== "none");
  let done = false;
  if (stream[_state] === "closed") {
- assert(pullIntoDescriptor.bytesFilled === 0);
+ assert(
+ pullIntoDescriptor.bytesFilled % pullIntoDescriptor.elementSize === 0,
+ );
  done = true;
  }
  const filledView = readableByteStreamControllerConvertPullIntoDescriptor(
@@ -2340,19 +2354,18 @@ function readableByteStreamControllerFillPullIntoDescriptorFromQueue(
  controller,
  pullIntoDescriptor,
 ) {
- const elementSize = pullIntoDescriptor.elementSize;
- const currentAlignedBytes = pullIntoDescriptor.bytesFilled -
- (pullIntoDescriptor.bytesFilled % elementSize);
  const maxBytesToCopy = MathMin(
  controller[_queueTotalSize],
  // deno-lint-ignore prefer-primordials
  pullIntoDescriptor.byteLength - pullIntoDescriptor.bytesFilled,
  );
  const maxBytesFilled = pullIntoDescriptor.bytesFilled + maxBytesToCopy;
- const maxAlignedBytes = maxBytesFilled - (maxBytesFilled % elementSize);
  let totalBytesToCopyRemaining = maxBytesToCopy;
  let ready = false;
- if (maxAlignedBytes > currentAlignedBytes) {
+ assert(pullIntoDescriptor.bytesFilled < pullIntoDescriptor.minimumFill);
+ const maxAlignedBytes = maxBytesFilled -
+ (maxBytesFilled % pullIntoDescriptor.elementSize);
+ if (maxAlignedBytes >= pullIntoDescriptor.minimumFill) {
  totalBytesToCopyRemaining = maxAlignedBytes -
  pullIntoDescriptor.bytesFilled;
  ready = true;
@@ -2402,7 +2415,7 @@ function readableByteStreamControllerFillPullIntoDescriptorFromQueue(
  if (!ready) {
  assert(controller[_queueTotalSize] === 0);
  assert(pullIntoDescriptor.bytesFilled > 0);
- assert(pullIntoDescriptor.bytesFilled < pullIntoDescriptor.elementSize);
+ assert(pullIntoDescriptor.bytesFilled < pullIntoDescriptor.minimumFill);
  }
  return ready;
 }
@@ -3375,7 +3388,7 @@ function readableByteStreamTee(stream) {
  reading = false;
  },
  };
- readableStreamBYOBReaderRead(reader, view, readIntoRequest);
+ readableStreamBYOBReaderRead(reader, view, 1, readIntoRequest);
  }
 
  function pull1Algorithm() {
@@ -5543,13 +5556,19 @@ class ReadableStreamBYOBReader {
 
  /**
  * @param {ArrayBufferView} view
+ * @param {ReadableStreamBYOBReaderReadOptions} options
  * @returns {Promise<ReadableStreamBYOBReadResult>}
  */
- read(view) {
+ read(view, options = {}) {
  try {
  webidl.assertBranded(this, ReadableStreamBYOBReaderPrototype);
  const prefix = "Failed to execute 'read' on 'ReadableStreamBYOBReader'";
  view = webidl.converters.ArrayBufferView(view, prefix, "Argument 1");
+ options = webidl.converters.ReadableStreamBYOBReaderReadOptions(
+ options,
+ prefix,
+ "Argument 2",
+ );
  } catch (err) {
  return PromiseReject(err);
  }
@@ -5584,6 +5603,23 @@ class ReadableStreamBYOBReader {
  );
  }
 
+ if (options.min === 0) {
+ return PromiseReject(new TypeError("options.min must be non-zero"));
+ }
+ if (TypedArrayPrototypeGetSymbolToStringTag(view) !== undefined) {
+ if (options.min > TypedArrayPrototypeGetLength(view)) {
+ return PromiseReject(
+ new RangeError("options.min must be smaller or equal to view's size"),
+ );
+ }
+ } else {
+ if (options.min > DataViewPrototypeGetByteLength(view)) {
+ return PromiseReject(
+ new RangeError("options.min must be smaller or equal to view's size"),
+ );
+ }
+ }
+
  if (this[_stream] === undefined) {
  return PromiseReject(
  new TypeError("Reader has no associated stream."),
@@ -5603,7 +5639,7 @@ class ReadableStreamBYOBReader {
  promise.reject(e);
  },
  };
- readableStreamBYOBReaderRead(this, view, readIntoRequest);
+ readableStreamBYOBReaderRead(this, view, options.min, readIntoRequest);
  return promise.promise;
  }
 
@@ -5929,6 +5965,7 @@ class ReadableByteStreamController {
  byteLength: autoAllocateChunkSize,
  bytesFilled: 0,
  elementSize: 1,
+ minimumFill: 1,
  viewConstructor: Uint8Array,
  readerType: "default",
  };
@@ -6799,6 +6836,17 @@ webidl.converters.ReadableStreamGetReaderOptions = webidl
  converter: webidl.converters.ReadableStreamReaderMode,
  }]);
 
+webidl.converters.ReadableStreamBYOBReaderReadOptions = webidl
+ .createDictionaryConverter("ReadableStreamBYOBReaderReadOptions", [{
+ key: "min",
+ converter: (V, prefix, context, opts) =>
+ webidl.converters["unsigned long long"](V, prefix, context, {
+ ...opts,
+ enforceRange: true,
+ }),
+ defaultValue: 1,
+ }]);
+
 webidl.converters.ReadableWritablePair = webidl
  .createDictionaryConverter("ReadableWritablePair", [
  {

ext/web/06_streams_types.d.ts

@@ -30,6 +30,7 @@ interface PullIntoDescriptor {
  byteOffset: number;
  byteLength: number;
  bytesFilled: number;
+ minimumFill: number;
  elementSize: number;
  // deno-lint-ignore no-explicit-any
  viewConstructor: any;

ext/web/lib.deno_web.d.ts

@@ -623,12 +623,18 @@ declare type ReadableStreamBYOBReadResult<V extends ArrayBufferView> =
  | ReadableStreamBYOBReadDoneResult<V>
  | ReadableStreamBYOBReadValueResult<V>;
 
+/** @category Streams API */
+declare interface ReadableStreamBYOBReaderReadOptions {
+ min?: number;
+}
+
 /** @category Streams API */
 declare interface ReadableStreamBYOBReader {
  readonly closed: Promise<void>;
  cancel(reason?: any): Promise<void>;
  read<V extends ArrayBufferView>(
  view: V,
+ options?: ReadableStreamBYOBReaderReadOptions,
  ): Promise<ReadableStreamBYOBReadResult<V>>;
  releaseLock(): void;
 }

tools/wpt/expectation.json

@@ -3204,7 +3204,9 @@
  "respond-after-enqueue.any.html": true,
  "respond-after-enqueue.any.worker.html": true,
  "enqueue-with-detached-buffer.any.html": true,
- "enqueue-with-detached-buffer.any.worker.html": true
+ "enqueue-with-detached-buffer.any.worker.html": true,
+ "read-min.any.html": true,
+ "read-min.any.worker.html": true
  },
  "readable-streams": {
  "async-iterator.any.html": true,