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stream: enable usage of webstreams on compose()
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Refs: #39316
PR-URL: #46675
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
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debadree25 committed Feb 27, 2023
1 parent 176227f commit 8f10c66
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Showing 4 changed files with 619 additions and 52 deletions.
7 changes: 6 additions & 1 deletion doc/api/stream.md
Original file line number Diff line number Diff line change
Expand Up @@ -2774,11 +2774,16 @@ const server = http.createServer((req, res) => {

<!-- YAML
added: v16.9.0
changes:
- version: REPLACEME
pr-url: https://github.com/nodejs/node/pull/46675
description: Added support for webstreams.
-->

> Stability: 1 - `stream.compose` is experimental.
* `streams` {Stream\[]|Iterable\[]|AsyncIterable\[]|Function\[]}
* `streams` {Stream\[]|Iterable\[]|AsyncIterable\[]|Function\[]|
ReadableStream\[]|WritableStream\[]|TransformStream\[]}
* Returns: {stream.Duplex}

Combines two or more streams into a `Duplex` stream that writes to the
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178 changes: 128 additions & 50 deletions lib/internal/streams/compose.js
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@ const {
isNodeStream,
isReadable,
isWritable,
isWebStream,
isTransformStream,
isWritableStream,
isReadableStream,
} = require('internal/streams/utils');
const {
AbortError,
Expand All @@ -15,6 +19,7 @@ const {
ERR_MISSING_ARGS,
},
} = require('internal/errors');
const eos = require('internal/streams/end-of-stream');

module.exports = function compose(...streams) {
if (streams.length === 0) {
Expand All @@ -37,18 +42,32 @@ module.exports = function compose(...streams) {
}

for (let n = 0; n < streams.length; ++n) {
if (!isNodeStream(streams[n])) {
if (!isNodeStream(streams[n]) && !isWebStream(streams[n])) {
// TODO(ronag): Add checks for non streams.
continue;
}
if (n < streams.length - 1 && !isReadable(streams[n])) {
if (
n < streams.length - 1 &&
!(
isReadable(streams[n]) ||
isReadableStream(streams[n]) ||
isTransformStream(streams[n])
)
) {
throw new ERR_INVALID_ARG_VALUE(
`streams[${n}]`,
orgStreams[n],
'must be readable'
);
}
if (n > 0 && !isWritable(streams[n])) {
if (
n > 0 &&
!(
isWritable(streams[n]) ||
isWritableStream(streams[n]) ||
isTransformStream(streams[n])
)
) {
throw new ERR_INVALID_ARG_VALUE(
`streams[${n}]`,
orgStreams[n],
Expand Down Expand Up @@ -79,8 +98,16 @@ module.exports = function compose(...streams) {
const head = streams[0];
const tail = pipeline(streams, onfinished);

const writable = !!isWritable(head);
const readable = !!isReadable(tail);
const writable = !!(
isWritable(head) ||
isWritableStream(head) ||
isTransformStream(head)
);
const readable = !!(
isReadable(tail) ||
isReadableStream(tail) ||
isTransformStream(tail)
);

// TODO(ronag): Avoid double buffering.
// Implement Writable/Readable/Duplex traits.
Expand All @@ -94,28 +121,55 @@ module.exports = function compose(...streams) {
});

if (writable) {
d._write = function(chunk, encoding, callback) {
if (head.write(chunk, encoding)) {
callback();
} else {
ondrain = callback;
}
};

d._final = function(callback) {
head.end();
onfinish = callback;
};
if (isNodeStream(head)) {
d._write = function(chunk, encoding, callback) {
if (head.write(chunk, encoding)) {
callback();
} else {
ondrain = callback;
}
};

d._final = function(callback) {
head.end();
onfinish = callback;
};

head.on('drain', function() {
if (ondrain) {
const cb = ondrain;
ondrain = null;
cb();
}
});
} else if (isWebStream(head)) {
const writable = isTransformStream(head) ? head.writable : head;
const writer = writable.getWriter();

d._write = async function(chunk, encoding, callback) {
try {
await writer.ready;
writer.write(chunk).catch(() => {});
callback();
} catch (err) {
callback(err);
}
};

d._final = async function(callback) {
try {
await writer.ready;
writer.close().catch(() => {});
onfinish = callback;
} catch (err) {
callback(err);
}
};
}

head.on('drain', function() {
if (ondrain) {
const cb = ondrain;
ondrain = null;
cb();
}
});
const toRead = isTransformStream(tail) ? tail.readable : tail;

tail.on('finish', function() {
eos(toRead, () => {
if (onfinish) {
const cb = onfinish;
onfinish = null;
Expand All @@ -125,32 +179,54 @@ module.exports = function compose(...streams) {
}

if (readable) {
tail.on('readable', function() {
if (onreadable) {
const cb = onreadable;
onreadable = null;
cb();
}
});

tail.on('end', function() {
d.push(null);
});

d._read = function() {
while (true) {
const buf = tail.read();

if (buf === null) {
onreadable = d._read;
return;
if (isNodeStream(tail)) {
tail.on('readable', function() {
if (onreadable) {
const cb = onreadable;
onreadable = null;
cb();
}

if (!d.push(buf)) {
return;
});

tail.on('end', function() {
d.push(null);
});

d._read = function() {
while (true) {
const buf = tail.read();
if (buf === null) {
onreadable = d._read;
return;
}

if (!d.push(buf)) {
return;
}
}
}
};
};
} else if (isWebStream(tail)) {
const readable = isTransformStream(tail) ? tail.readable : tail;
const reader = readable.getReader();
d._read = async function() {
while (true) {
try {
const { value, done } = await reader.read();

if (!d.push(value)) {
return;
}

if (done) {
d.push(null);
return;
}
} catch {
return;
}
}
};
}
}

d._destroy = function(err, callback) {
Expand All @@ -166,7 +242,9 @@ module.exports = function compose(...streams) {
callback(err);
} else {
onclose = callback;
destroyer(tail, err);
if (isNodeStream(tail)) {
destroyer(tail, err);
}
}
};

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3 changes: 2 additions & 1 deletion lib/internal/streams/pipeline.js
Original file line number Diff line number Diff line change
Expand Up @@ -286,7 +286,7 @@ function pipelineImpl(streams, callback, opts) {
throw new ERR_INVALID_RETURN_VALUE(
'Iterable, AsyncIterable or Stream', 'source', ret);
}
} else if (isIterable(stream) || isReadableNodeStream(stream)) {
} else if (isIterable(stream) || isReadableNodeStream(stream) || isTransformStream(stream)) {
ret = stream;
} else {
ret = Duplex.from(stream);
Expand Down Expand Up @@ -385,6 +385,7 @@ function pipelineImpl(streams, callback, opts) {
finishCount++;
pumpToWeb(ret, stream, finish, { end });
} else if (isTransformStream(ret)) {
finishCount++;
pumpToWeb(ret.readable, stream, finish, { end });
} else {
throw new ERR_INVALID_ARG_TYPE(
Expand Down
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