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stream: add AbortSignal to promisified pipeline
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add support for AbortSignal to promisified pipeline.

Resolves: #37321
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Nitzan Uziely committed Feb 14, 2021
1 parent 88d9268 commit dc74b35
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Showing 3 changed files with 145 additions and 2 deletions.
30 changes: 29 additions & 1 deletion doc/api/stream.md
Original file line number Diff line number Diff line change
Expand Up @@ -1719,7 +1719,11 @@ pipeline(
);
```

The `pipeline` API provides promise version:
The `pipeline` API provides a promise version, which can also
receive an options argument as the last parameter with a
`signal` {AbortSignal} property. When the signal is aborted,
`destroy` will be called on the underlying pipeline, with an
`AbortError`.

```js
const { pipeline } = require('stream/promises');
Expand All @@ -1736,6 +1740,30 @@ async function run() {
run().catch(console.error);
```

To use an `AbortSignal`, pass it inside an options object,
as the last argument:

```js
const { pipeline } = require('stream/promises');

async function run() {
const ac = new AbortController();
const options = {
signal: ac.signal,
};

setTimeout(() => ac.abort(), 1);
await pipeline(
fs.createReadStream('archive.tar'),
zlib.createGzip(),
fs.createWriteStream('archive.tar.gz'),
options,
);
}

run().catch(console.error); // AbortError
```

The `pipeline` API also supports async generators:

```js
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45 changes: 44 additions & 1 deletion lib/stream/promises.js
Original file line number Diff line number Diff line change
@@ -1,22 +1,65 @@
'use strict';

const {
ArrayPrototypePop,
Promise,
SymbolAsyncIterator,
SymbolIterator,
} = primordials;

const {
addAbortSignalNoValidate,
} = require('internal/streams/add-abort-signal');

const {
validateAbortSignal,
} = require('internal/validators');

let pl;
let eos;

function isReadable(obj) {
return !!(obj && typeof obj.pipe === 'function');
}

function isWritable(obj) {
return !!(obj && typeof obj.write === 'function');
}

function isStream(obj) {
return isReadable(obj) || isWritable(obj);
}

function isIterable(obj, isAsync) {
if (!obj) return false;
if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
if (isAsync === false) return typeof obj[SymbolIterator] === 'function';
return typeof obj[SymbolAsyncIterator] === 'function' ||
typeof obj[SymbolIterator] === 'function';
}

function pipeline(...streams) {
if (!pl) pl = require('internal/streams/pipeline');
return new Promise((resolve, reject) => {
pl(...streams, (err, value) => {
let signal;
const lastArg = streams[streams.length - 1];
if (lastArg && typeof lastArg === 'object' &&
!isStream(lastArg) && !isIterable(lastArg)) {
const options = ArrayPrototypePop(streams);
signal = options.signal;
validateAbortSignal(signal, 'options.signal');
}

const pipe = pl(...streams, (err, value) => {
if (err) {
reject(err);
} else {
resolve(value);
}
});
if (signal) {
addAbortSignalNoValidate(signal, pipe);
}
});
}

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72 changes: 72 additions & 0 deletions test/parallel/test-stream-pipeline.js
Original file line number Diff line number Diff line change
Expand Up @@ -469,6 +469,78 @@ const net = require('net');
run();
}

{
// Check aborted signal without values
const pipelinePromise = promisify(pipeline);
async function run() {
const ac = new AbortController();
const { signal } = ac;
async function* producer() {
ac.abort();
await Promise.resolve();
yield '8';
}

const w = new Writable({
write(chunk, encoding, callback) {
callback();
}
});
await pipelinePromise(producer, w, { signal });
}

assert.rejects(run, { name: 'AbortError' }).then(common.mustCall());
}

{
// Check aborted signal after init.
const pipelinePromise = promisify(pipeline);
async function run() {
const ac = new AbortController();
const { signal } = ac;
async function* producer() {
yield '5';
await Promise.resolve();
ac.abort();
await Promise.resolve();
yield '8';
}

const w = new Writable({
write(chunk, encoding, callback) {
callback();
}
});
await pipelinePromise(producer, w, { signal });
}

assert.rejects(run, { name: 'AbortError' }).then(common.mustCall());
}

{
// Check pre-aborted signal
const pipelinePromise = promisify(pipeline);
async function run() {
const ac = new AbortController();
const { signal } = ac;
ac.abort();
async function* producer() {
yield '5';
await Promise.resolve();
yield '8';
}

const w = new Writable({
write(chunk, encoding, callback) {
callback();
}
});
await pipelinePromise(producer, w, { signal });
}

assert.rejects(run, { name: 'AbortError' }).then(common.mustCall());
}

{
const read = new Readable({
read() {}
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