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stream: Fix readableState.awaitDrain mechanism

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In 68990948fe4 (https://github.com/nodejs/node/pull/2325),
the conditions for increasing `readableState.awaitDrain` when
writing to a piping destination returns false were changed so
that they could not actually be met, effectively leaving
`readableState.awaitDrain` with a constant value of 0.

This patch changes the conditions to testing whether the
stream for which `.write()` returned false is still a piping
destination, which was likely the intention of the original
patch.

Fixes: https://github.com/nodejs/node/issues/5820
Fixes: https://github.com/nodejs/node/issues/5257
PR-URL: https://github.com/nodejs/node/pull/6023
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
This commit is contained in:
Anna Henningsen 2016-04-03 00:37:49 +02:00 committed by James M Snell
parent 5dafb435d8
commit 819b2d36bc
2 changed files with 43 additions and 3 deletions
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6
lib/_stream_readable.js
View File

@ -538,9 +538,9 @@ Readable.prototype.pipe = function(dest, pipeOpts) {
// If the user unpiped during `dest.write()`, it is possible
// to get stuck in a permanently paused state if that write
// also returned false.
if (state.pipesCount === 1 &&
state.pipes[0] === dest &&
src.listenerCount('data') === 1 &&
// => Check whether `dest` is still a piping destination.
if (((state.pipesCount === 1 && state.pipes === dest) ||
(state.pipesCount > 1 && state.pipes.indexOf(dest) !== -1)) &&
!cleanedUp) {
debug('false write response, pause', src._readableState.awaitDrain);
src._readableState.awaitDrain++;

40
test/parallel/test-stream-pipe-await-drain.js Normal file
View File

@ -0,0 +1,40 @@
'use strict';
const common = require('../common');
const stream = require('stream');
// This is very similar to test-stream-pipe-cleanup-pause.js.
const reader = new stream.Readable();
const writer1 = new stream.Writable();
const writer2 = new stream.Writable();
// 560000 is chosen here because it is larger than the (default) highWaterMark
// and will cause `.write()` to return false
// See: https://github.com/nodejs/node/issues/5820
const buffer = Buffer.allocUnsafe(560000);
reader._read = function(n) {};
writer1._write = common.mustCall(function(chunk, encoding, cb) {
this.emit('chunk-received');
cb();
}, 1);
writer1.once('chunk-received', function() {
setImmediate(function() {
// This one should *not* get through to writer1 because writer2 is not
// "done" processing.
reader.push(buffer);
});
});
// A "slow" consumer:
writer2._write = common.mustCall(function(chunk, encoding, cb) {
// Not calling cb here to "simulate" slow stream.
// This should be called exactly once, since the first .write() call
// will return false.
}, 1);
reader.pipe(writer1);
reader.pipe(writer2);
reader.push(buffer);