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stream: add readableDidRead if has been read from · nodejs/node@a62d4d6 · GitHub

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stream: add readableDidRead if has been read from
Adds did read accessor used to determine whether a readable has been read from. PR-URL: #39589 Refs: nodejs/undici#907 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
1 parent 989c204 commit a62d4d6

3 files changed

Lines changed: 133 additions & 1 deletion

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‎doc/api/stream.md‎

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@@ -1211,6 +1211,17 @@ added: v11.4.0
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Is `true` if it is safe to call [`readable.read()`][stream-read], which means
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the stream has not been destroyed or emitted `'error'` or `'end'`.
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##### `readable.readableDidRead`
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<!-- YAML
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added: REPLACEME
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-->
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* {boolean}
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Allows determining if the stream has been or is about to be read.
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Returns true if `'data'`, `'end'`, `'error'` or `'close'` has been
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emitted.
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##### `readable.readableEncoding`
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<!-- YAML
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added: v12.7.0

‎lib/internal/streams/readable.js‎

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@@ -154,6 +154,8 @@ function ReadableState(options, stream, isDuplex) {
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// If true, a maybeReadMore has been scheduled.
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this.readingMore = false;
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this.dataEmitted = false;
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this.decoder = null;
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this.encoding = null;
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if (options && options.encoding) {
@@ -287,6 +289,7 @@ function addChunk(stream, state, chunk, addToFront) {
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} else {
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state.awaitDrainWriters = null;
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}
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state.dataEmitted = true;
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stream.emit('data', chunk);
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} else {
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// Update the buffer info.
@@ -496,8 +499,10 @@ Readable.prototype.read = function(n) {
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endReadable(this);
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}
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if (ret !== null)
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if (ret !== null) {
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state.dataEmitted = true;
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this.emit('data', ret);
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}
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return ret;
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};
@@ -1169,6 +1174,18 @@ ObjectDefineProperties(Readable.prototype, {
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}
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},
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readableDidRead: {
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enumerable: false,
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get: function() {
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return (
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this._readableState.dataEmitted ||
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this._readableState.endEmitted ||
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this._readableState.errorEmitted ||
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this._readableState.closeEmitted
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);
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}
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},
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readableHighWaterMark: {
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enumerable: false,
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get: function() {

‎test/parallel/test-stream-readable-didRead.js‎

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@@ -0,0 +1,104 @@
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'use strict';
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const common = require('../common');
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const assert = require('assert');
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const Readable = require('stream').Readable;
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function noop() {}
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function check(readable, data, fn) {
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assert.strictEqual(readable.readableDidRead, false);
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if (data === -1) {
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readable.on('error', common.mustCall());
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readable.on('data', common.mustNotCall());
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readable.on('end', common.mustNotCall());
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} else {
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readable.on('error', common.mustNotCall());
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if (data === -2) {
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readable.on('end', common.mustNotCall());
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} else {
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readable.on('end', common.mustCall());
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}
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if (data > 0) {
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readable.on('data', common.mustCallAtLeast(data));
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} else {
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readable.on('data', common.mustNotCall());
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}
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}
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readable.on('close', common.mustCall());
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fn();
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setImmediate(() => {
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assert.strictEqual(readable.readableDidRead, true);
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push(null);
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}
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});
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check(readable, 0, () => {
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readable.read();
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push(null);
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}
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});
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check(readable, 0, () => {
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readable.resume();
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push(null);
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}
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});
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check(readable, -2, () => {
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readable.destroy();
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push(null);
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}
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});
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check(readable, -1, () => {
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readable.destroy(new Error());
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push('data');
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this.push(null);
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}
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});
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check(readable, 1, () => {
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readable.on('data', noop);
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});
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}
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{
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const readable = new Readable({
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read() {
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this.push('data');
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this.push(null);
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}
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});
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check(readable, 1, () => {
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readable.on('data', noop);
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readable.off('data', noop);
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});
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}

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