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ronag wants to merge 5 commits into from
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stream: async iterator improvements #31316

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711997e
stream: add async iterator support for v1 streams
ronag Jan 11, 2020
7f8d7da
stream: normalize async iterator stream destroy
ronag Jan 11, 2020
0620728
stream: implement throw for async iterator
ronag Jan 11, 2020
0ea887c
stream: simplify pipeline
ronag Jan 18, 2020
3201faa
stream: re-use legacy destroyer
ronag Jan 21, 2020
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stream: implement throw for async iterator
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@ronag
ronag committed Jan 18, 2020
commit 0620728a9a53b0daf1b068a0cdc41ecfe200d8c4
49 changes: 29 additions & 20 deletions lib/internal/streams/async_iterator.js
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,31 @@ function wrapForNext(lastPromise, iter) {
const AsyncIteratorPrototype = ObjectGetPrototypeOf(
ObjectGetPrototypeOf(async function* () {}).prototype);

function finish(self, err) {
return new Promise((resolve, reject) => {
const stream = self[kStream];

// TODO(ronag): Remove this check once finished() handles
// already ended and/or destroyed streams.
const ended = stream.destroyed || stream.readableEnded ||
(stream._readableState && stream._readableState.endEmitted);

if (ended) {
resolve(createIterResult(undefined, true));
return;
}

finished(stream, (err) => {
if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
reject(err);
} else {
resolve(createIterResult(undefined, true));
}
});
destroy(stream, err);
});
}

const ReadableStreamAsyncIteratorPrototype = ObjectSetPrototypeOf({
get stream() {
return this[kStream];
Expand Down Expand Up @@ -131,27 +156,11 @@ const ReadableStreamAsyncIteratorPrototype = ObjectSetPrototypeOf({
},

return() {
return new Promise((resolve, reject) => {
const stream = this[kStream];

// TODO(ronag): Remove this check once finished() handles
// already ended and/or destroyed streams.
const ended = stream.destroyed || stream.readableEnded ||
(stream._readableState && stream._readableState.endEmitted);
if (ended) {
resolve(createIterResult(undefined, true));
return;
}
return finish(this);
},

finished(stream, (err) => {
if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
reject(err);
} else {
resolve(createIterResult(undefined, true));
}
});
destroy(stream);
});
throw(err) {
return finish(this, err);
},
}, AsyncIteratorPrototype);

Expand Down
22 changes: 22 additions & 0 deletions test/parallel/test-stream-readable-async-iterators.js
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Expand Up @@ -282,6 +282,28 @@ async function tests() {
assert.strictEqual(received, 1);
}

{
// Iterator throw.

const readable = new Readable({
objectMode: true,
read() {
this.push('hello');
}
});

readable.on('error', common.mustCall((err) => {
assert.strictEqual(err.message, 'kaboom');
}));

const it = readable[Symbol.asyncIterator]();
it.throw(new Error('kaboom')).catch(common.mustCall((err) => {
assert.strictEqual(err.message, 'kaboom');
}));

assert.strictEqual(readable.destroyed, true);
}

{
console.log('destroyed by throw');
const readable = new Readable({
Expand Down