You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

915 lines
25 KiB

// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
module.exports = Readable;
Readable.ReadableState = ReadableState;
var EE = require('events').EventEmitter;
var Stream = require('stream');
var util = require('util');
var StringDecoder;
util.inherits(Readable, Stream);
function ReadableState(options, stream) {
options = options || {};
// the point at which it stops calling _read() to fill the buffer
// Note: 0 is a valid value, means "don't call _read preemptively ever"
var hwm = options.highWaterMark;
this.highWaterMark = (hwm || hwm === 0) ? hwm : 16 * 1024;
// cast to ints.
this.highWaterMark = ~~this.highWaterMark;
this.buffer = [];
this.length = 0;
this.pipes = null;
this.pipesCount = 0;
this.flowing = false;
this.ended = false;
this.endEmitted = false;
this.reading = false;
// In streams that never have any data, and do push(null) right away,
// the consumer can miss the 'end' event if they do some I/O before
// consuming the stream. So, we don't emit('end') until some reading
// happens.
this.calledRead = false;
// a flag to be able to tell if the onwrite cb is called immediately,
// or on a later tick. We set this to true at first, becuase any
// actions that shouldn't happen until "later" should generally also
// not happen before the first write call.
this.sync = true;
// whenever we return null, then we set a flag to say
// that we're awaiting a 'readable' event emission.
this.needReadable = false;
this.emittedReadable = false;
this.readableListening = false;
// object stream flag. Used to make read(n) ignore n and to
// make all the buffer merging and length checks go away
this.objectMode = !!options.objectMode;
// Crypto is kind of old and crusty. Historically, its default string
// encoding is 'binary' so we have to make this configurable.
// Everything else in the universe uses 'utf8', though.
this.defaultEncoding = options.defaultEncoding || 'utf8';
// when piping, we only care about 'readable' events that happen
// after read()ing all the bytes and not getting any pushback.
this.ranOut = false;
// the number of writers that are awaiting a drain event in .pipe()s
this.awaitDrain = 0;
// if true, a maybeReadMore has been scheduled
this.readingMore = false;
this.decoder = null;
this.encoding = null;
if (options.encoding) {
if (!StringDecoder)
StringDecoder = require('string_decoder').StringDecoder;
this.decoder = new StringDecoder(options.encoding);
this.encoding = options.encoding;
}
}
function Readable(options) {
if (!(this instanceof Readable))
return new Readable(options);
this._readableState = new ReadableState(options, this);
// legacy
this.readable = true;
Stream.call(this);
}
// Manually shove something into the read() buffer.
// This returns true if the highWaterMark has not been hit yet,
// similar to how Writable.write() returns true if you should
// write() some more.
Readable.prototype.push = function(chunk, encoding) {
var state = this._readableState;
if (typeof chunk === 'string' && !state.objectMode) {
encoding = encoding || state.defaultEncoding;
if (encoding !== state.encoding) {
chunk = new Buffer(chunk, encoding);
encoding = '';
}
}
return readableAddChunk(this, state, chunk, encoding, false);
};
// Unshift should *always* be something directly out of read()
Readable.prototype.unshift = function(chunk) {
var state = this._readableState;
return readableAddChunk(this, state, chunk, '', true);
};
function readableAddChunk(stream, state, chunk, encoding, addToFront) {
var er = chunkInvalid(state, chunk);
if (er) {
stream.emit('error', er);
} else if (chunk === null || chunk === undefined) {
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
state.reading = false;
if (!state.ended)
onEofChunk(stream, state);
} else if (state.objectMode || chunk && chunk.length > 0) {
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
if (state.ended && !addToFront) {
var e = new Error('stream.push() after EOF');
stream.emit('error', e);
} else if (state.endEmitted && addToFront) {
var e = new Error('stream.unshift() after end event');
stream.emit('error', e);
} else {
if (state.decoder && !addToFront && !encoding)
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
chunk = state.decoder.write(chunk);
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
// update the buffer info.
state.length += state.objectMode ? 1 : chunk.length;
if (addToFront) {
state.buffer.unshift(chunk);
} else {
state.reading = false;
state.buffer.push(chunk);
}
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
if (state.needReadable)
emitReadable(stream);
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a 'reading' flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it's safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before "putting back" some bit of previously consumed data (as in the case of Node's websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don't tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the 'end' event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the 'end' event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another 'readable' event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the 'end' event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the 'end' event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
maybeReadMore(stream, state);
}
} else {
state.reading = false;
}
return needMoreData(state);
}
// if it's past the high water mark, we can push in some more.
// Also, if we have no data yet, we can stand some
// more bytes. This is to work around cases where hwm=0,
// such as the repl. Also, if the push() triggered a
// readable event, and the user called read(largeNumber) such that
// needReadable was set, then we ought to push more, so that another
// 'readable' event will be triggered.
function needMoreData(state) {
return !state.ended &&
(state.needReadable ||
state.length < state.highWaterMark ||
state.length === 0);
}
// backwards compatibility.
Readable.prototype.setEncoding = function(enc) {
if (!StringDecoder)
StringDecoder = require('string_decoder').StringDecoder;
this._readableState.decoder = new StringDecoder(enc);
this._readableState.encoding = enc;
};
// Don't raise the hwm > 128MB
var MAX_HWM = 0x800000;
function roundUpToNextPowerOf2(n) {
if (n >= MAX_HWM) {
n = MAX_HWM;
} else {
// Get the next highest power of 2
n--;
for (var p = 1; p < 32; p <<= 1) n |= n >> p;
n++;
}
return n;
}
function howMuchToRead(n, state) {
if (state.length === 0 && state.ended)
return 0;
if (state.objectMode)
return n === 0 ? 0 : 1;
if (isNaN(n) || n === null) {
// only flow one buffer at a time
if (state.flowing && state.buffer.length)
return state.buffer[0].length;
else
return state.length;
}
if (n <= 0)
return 0;
// If we're asking for more than the target buffer level,
// then raise the water mark. Bump up to the next highest
// power of 2, to prevent increasing it excessively in tiny
// amounts.
if (n > state.highWaterMark)
state.highWaterMark = roundUpToNextPowerOf2(n);
// don't have that much. return null, unless we've ended.
if (n > state.length) {
if (!state.ended) {
state.needReadable = true;
return 0;
} else
return state.length;
}
return n;
}
// you can override either this method, or the async _read(n) below.
Readable.prototype.read = function(n) {
var state = this._readableState;
state.calledRead = true;
var nOrig = n;
if (typeof n !== 'number' || n > 0)
state.emittedReadable = false;
// if we're doing read(0) to trigger a readable event, but we
// already have a bunch of data in the buffer, then just trigger
// the 'readable' event and move on.
if (n === 0 &&
state.needReadable &&
(state.length >= state.highWaterMark || state.ended)) {
emitReadable(this);
return null;
}
n = howMuchToRead(n, state);
// if we've ended, and we're now clear, then finish it up.
if (n === 0 && state.ended) {
if (state.length === 0)
endReadable(this);
return null;
}
// All the actual chunk generation logic needs to be
// *below* the call to _read. The reason is that in certain
// synthetic stream cases, such as passthrough streams, _read
// may be a completely synchronous operation which may change
// the state of the read buffer, providing enough data when
// before there was *not* enough.
//
// So, the steps are:
// 1. Figure out what the state of things will be after we do
// a read from the buffer.
//
// 2. If that resulting state will trigger a _read, then call _read.
// Note that this may be asynchronous, or synchronous. Yes, it is
// deeply ugly to write APIs this way, but that still doesn't mean
// that the Readable class should behave improperly, as streams are
// designed to be sync/async agnostic.
// Take note if the _read call is sync or async (ie, if the read call
// has returned yet), so that we know whether or not it's safe to emit
// 'readable' etc.
//
// 3. Actually pull the requested chunks out of the buffer and return.
// if we need a readable event, then we need to do some reading.
var doRead = state.needReadable;
// if we currently have less than the highWaterMark, then also read some
if (state.length - n <= state.highWaterMark)
doRead = true;
// however, if we've ended, then there's no point, and if we're already
// reading, then it's unnecessary.
if (state.ended || state.reading)
doRead = false;
if (doRead) {
state.reading = true;
state.sync = true;
// if the length is currently zero, then we *need* a readable event.
if (state.length === 0)
state.needReadable = true;
// call internal read method
this._read(state.highWaterMark);
state.sync = false;
}
// If _read called its callback synchronously, then `reading`
// will be false, and we need to re-evaluate how much data we
// can return to the user.
if (doRead && !state.reading)
n = howMuchToRead(nOrig, state);
var ret;
if (n > 0)
ret = fromList(n, state);
else
ret = null;
if (ret === null) {
state.needReadable = true;
n = 0;
}
state.length -= n;
// If we have nothing in the buffer, then we want to know
// as soon as we *do* get something into the buffer.
if (state.length === 0 && !state.ended)
state.needReadable = true;
// If we happened to read() exactly the remaining amount in the
// buffer, and the EOF has been seen at this point, then make sure
// that we emit 'end' on the very next tick.
if (state.ended && !state.endEmitted && state.length === 0)
endReadable(this);
return ret;
};
function chunkInvalid(state, chunk) {
var er = null;
if (!Buffer.isBuffer(chunk) &&
'string' !== typeof chunk &&
chunk !== null &&
chunk !== undefined &&
!state.objectMode &&
!er) {
er = new TypeError('Invalid non-string/buffer chunk');
}
return er;
}
function onEofChunk(stream, state) {
if (state.decoder && !state.ended) {
var chunk = state.decoder.end();
if (chunk && chunk.length) {
state.buffer.push(chunk);
state.length += state.objectMode ? 1 : chunk.length;
}
}
state.ended = true;
// if we've ended and we have some data left, then emit
// 'readable' now to make sure it gets picked up.
if (state.length > 0)
emitReadable(stream);
else
endReadable(stream);
}
// Don't emit readable right away in sync mode, because this can trigger
// another read() call => stack overflow. This way, it might trigger
// a nextTick recursion warning, but that's not so bad.
function emitReadable(stream) {
var state = stream._readableState;
state.needReadable = false;
if (state.emittedReadable)
return;
state.emittedReadable = true;
if (state.sync)
process.nextTick(function() {
emitReadable_(stream);
});
else
emitReadable_(stream);
}
function emitReadable_(stream) {
stream.emit('readable');
}
// at this point, the user has presumably seen the 'readable' event,
// and called read() to consume some data. that may have triggered
// in turn another _read(n) call, in which case reading = true if
// it's in progress.
// However, if we're not ended, or reading, and the length < hwm,
// then go ahead and try to read some more preemptively.
function maybeReadMore(stream, state) {
if (!state.readingMore) {
state.readingMore = true;
process.nextTick(function() {
maybeReadMore_(stream, state);
});
}
}
function maybeReadMore_(stream, state) {
var len = state.length;
while (!state.reading && !state.flowing && !state.ended &&
state.length < state.highWaterMark) {
stream.read(0);
if (len === state.length)
// didn't get any data, stop spinning.
break;
else
len = state.length;
}
state.readingMore = false;
}
// abstract method. to be overridden in specific implementation classes.
// call cb(er, data) where data is <= n in length.
// for virtual (non-string, non-buffer) streams, "length" is somewhat
// arbitrary, and perhaps not very meaningful.
Readable.prototype._read = function(n) {
this.emit('error', new Error('not implemented'));
};
Readable.prototype.pipe = function(dest, pipeOpts) {
var src = this;
var state = this._readableState;
switch (state.pipesCount) {
case 0:
state.pipes = dest;
break;
case 1:
12 years ago
state.pipes = [state.pipes, dest];
break;
default:
state.pipes.push(dest);
break;
}
state.pipesCount += 1;
var doEnd = (!pipeOpts || pipeOpts.end !== false) &&
dest !== process.stdout &&
dest !== process.stderr;
var endFn = doEnd ? onend : cleanup;
if (state.endEmitted)
process.nextTick(endFn);
else
src.once('end', endFn);
dest.on('unpipe', onunpipe);
function onunpipe(readable) {
if (readable !== src) return;
cleanup();
}
function onend() {
dest.end();
}
// when the dest drains, it reduces the awaitDrain counter
// on the source. This would be more elegant with a .once()
// handler in flow(), but adding and removing repeatedly is
// too slow.
var ondrain = pipeOnDrain(src);
dest.on('drain', ondrain);
function cleanup() {
// cleanup event handlers once the pipe is broken
dest.removeListener('close', onclose);
dest.removeListener('finish', onfinish);
dest.removeListener('drain', ondrain);
dest.removeListener('error', onerror);
dest.removeListener('unpipe', onunpipe);
src.removeListener('end', onend);
src.removeListener('end', cleanup);
// if the reader is waiting for a drain event from this
// specific writer, then it would cause it to never start
// flowing again.
// So, if this is awaiting a drain, then we just call it now.
// If we don't know, then assume that we are waiting for one.
if (!dest._writableState || dest._writableState.needDrain)
ondrain();
}
// if the dest has an error, then stop piping into it.
// however, don't suppress the throwing behavior for this.
function onerror(er) {
unpipe();
if (EE.listenerCount(dest, 'error') === 0)
dest.emit('error', er);
}
dest.once('error', onerror);
// Both close and finish should trigger unpipe, but only once.
function onclose() {
dest.removeListener('finish', onfinish);
unpipe();
}
dest.once('close', onclose);
function onfinish() {
dest.removeListener('close', onclose);
unpipe();
}
dest.once('finish', onfinish);
function unpipe() {
src.unpipe(dest);
}
// tell the dest that it's being piped to
dest.emit('pipe', src);
// start the flow if it hasn't been started already.
if (!state.flowing) {
// the handler that waits for readable events after all
// the data gets sucked out in flow.
// This would be easier to follow with a .once() handler
// in flow(), but that is too slow.
this.on('readable', pipeOnReadable);
state.flowing = true;
process.nextTick(function() {
flow(src);
});
}
return dest;
};
function pipeOnDrain(src) {
return function() {
var dest = this;
var state = src._readableState;
12 years ago
state.awaitDrain--;
if (state.awaitDrain === 0)
flow(src);
};
}
function flow(src) {
var state = src._readableState;
var chunk;
state.awaitDrain = 0;
function write(dest, i, list) {
var written = dest.write(chunk);
if (false === written) {
state.awaitDrain++;
}
}
while (state.pipesCount && null !== (chunk = src.read())) {
if (state.pipesCount === 1)
write(state.pipes, 0, null);
else
state.pipes.forEach(write);
src.emit('data', chunk);
// if anyone needs a drain, then we have to wait for that.
if (state.awaitDrain > 0)
return;
}
// if every destination was unpiped, either before entering this
// function, or in the while loop, then stop flowing.
//
// NB: This is a pretty rare edge case.
if (state.pipesCount === 0) {
state.flowing = false;
// if there were data event listeners added, then switch to old mode.
if (EE.listenerCount(src, 'data') > 0)
emitDataEvents(src);
return;
}
// at this point, no one needed a drain, so we just ran out of data
// on the next readable event, start it over again.
state.ranOut = true;
}
function pipeOnReadable() {
if (this._readableState.ranOut) {
this._readableState.ranOut = false;
flow(this);
}
}
Readable.prototype.unpipe = function(dest) {
var state = this._readableState;
// if we're not piping anywhere, then do nothing.
if (state.pipesCount === 0)
return this;
// just one destination. most common case.
if (state.pipesCount === 1) {
// passed in one, but it's not the right one.
if (dest && dest !== state.pipes)
return this;
if (!dest)
dest = state.pipes;
// got a match.
state.pipes = null;
state.pipesCount = 0;
this.removeListener('readable', pipeOnReadable);
state.flowing = false;
if (dest)
dest.emit('unpipe', this);
return this;
}
// slow case. multiple pipe destinations.
if (!dest) {
// remove all.
var dests = state.pipes;
var len = state.pipesCount;
state.pipes = null;
state.pipesCount = 0;
this.removeListener('readable', pipeOnReadable);
state.flowing = false;
for (var i = 0; i < len; i++)
dests[i].emit('unpipe', this);
return this;
}
// try to find the right one.
var i = state.pipes.indexOf(dest);
if (i === -1)
return this;
state.pipes.splice(i, 1);
state.pipesCount -= 1;
if (state.pipesCount === 1)
state.pipes = state.pipes[0];
dest.emit('unpipe', this);
return this;
};
// set up data events if they are asked for
// Ensure readable listeners eventually get something
Readable.prototype.on = function(ev, fn) {
var res = Stream.prototype.on.call(this, ev, fn);
if (ev === 'data' && !this._readableState.flowing)
emitDataEvents(this);
if (ev === 'readable' && this.readable) {
var state = this._readableState;
if (!state.readableListening) {
state.readableListening = true;
state.emittedReadable = false;
state.needReadable = true;
if (!state.reading) {
this.read(0);
} else if (state.length) {
emitReadable(this, state);
}
}
}
return res;
};
Readable.prototype.addListener = Readable.prototype.on;
// pause() and resume() are remnants of the legacy readable stream API
// If the user uses them, then switch into old mode.
Readable.prototype.resume = function() {
emitDataEvents(this);
this.read(0);
this.emit('resume');
};
Readable.prototype.pause = function() {
emitDataEvents(this, true);
this.emit('pause');
};
function emitDataEvents(stream, startPaused) {
var state = stream._readableState;
if (state.flowing) {
// https://github.com/isaacs/readable-stream/issues/16
throw new Error('Cannot switch to old mode now.');
}
var paused = startPaused || false;
var readable = false;
// convert to an old-style stream.
stream.readable = true;
stream.pipe = Stream.prototype.pipe;
stream.on = stream.addListener = Stream.prototype.on;
stream.on('readable', function() {
readable = true;
var c;
while (!paused && (null !== (c = stream.read())))
stream.emit('data', c);
if (c === null) {
readable = false;
stream._readableState.needReadable = true;
}
});
stream.pause = function() {
paused = true;
this.emit('pause');
};
stream.resume = function() {
paused = false;
if (readable)
process.nextTick(function() {
stream.emit('readable');
});
else
this.read(0);
this.emit('resume');
};
// now make it start, just in case it hadn't already.
stream.emit('readable');
}
// wrap an old-style stream as the async data source.
// This is *not* part of the readable stream interface.
// It is an ugly unfortunate mess of history.
Readable.prototype.wrap = function(stream) {
var state = this._readableState;
var paused = false;
var self = this;
stream.on('end', function() {
if (state.decoder && !state.ended) {
var chunk = state.decoder.end();
if (chunk && chunk.length)
self.push(chunk);
}
self.push(null);
});
stream.on('data', function(chunk) {
if (state.decoder)
chunk = state.decoder.write(chunk);
if (!chunk || !state.objectMode && !chunk.length)
return;
var ret = self.push(chunk);
if (!ret) {
paused = true;
stream.pause();
}
});
// proxy all the other methods.
// important when wrapping filters and duplexes.
for (var i in stream) {
if (typeof stream[i] === 'function' &&
typeof this[i] === 'undefined') {
this[i] = function(method) { return function() {
return stream[method].apply(stream, arguments);
}}(i);
}
}
// proxy certain important events.
var events = ['error', 'close', 'destroy', 'pause', 'resume'];
events.forEach(function(ev) {
stream.on(ev, self.emit.bind(self, ev));
});
// when we try to consume some more bytes, simply unpause the
// underlying stream.
self._read = function(n) {
if (paused) {
paused = false;
stream.resume();
}
};
return self;
};
// exposed for testing purposes only.
Readable._fromList = fromList;
// Pluck off n bytes from an array of buffers.
// Length is the combined lengths of all the buffers in the list.
function fromList(n, state) {
var list = state.buffer;
var length = state.length;
var stringMode = !!state.decoder;
var objectMode = !!state.objectMode;
var ret;
// nothing in the list, definitely empty.
if (list.length === 0)
return null;
if (length === 0)
ret = null;
else if (objectMode)
ret = list.shift();
else if (!n || n >= length) {
// read it all, truncate the array.
if (stringMode)
ret = list.join('');
else
ret = Buffer.concat(list, length);
list.length = 0;
} else {
// read just some of it.
if (n < list[0].length) {
// just take a part of the first list item.
// slice is the same for buffers and strings.
var buf = list[0];
ret = buf.slice(0, n);
list[0] = buf.slice(n);
} else if (n === list[0].length) {
// first list is a perfect match
ret = list.shift();
} else {
// complex case.
// we have enough to cover it, but it spans past the first buffer.
if (stringMode)
ret = '';
else
ret = new Buffer(n);
var c = 0;
for (var i = 0, l = list.length; i < l && c < n; i++) {
var buf = list[0];
var cpy = Math.min(n - c, buf.length);
if (stringMode)
ret += buf.slice(0, cpy);
else
buf.copy(ret, c, 0, cpy);
if (cpy < buf.length)
list[0] = buf.slice(cpy);
else
list.shift();
c += cpy;
}
}
}
return ret;
}
function endReadable(stream) {
var state = stream._readableState;
// If we get here before consuming all the bytes, then that is a
// bug in node. Should never happen.
if (state.length > 0)
throw new Error('endReadable called on non-empty stream');
if (!state.endEmitted && state.calledRead) {
state.ended = true;
process.nextTick(function() {
stream: Fix unshift() race conditions Fix #5272 The consumption of a readable stream is a dance with 3 partners. 1. The specific stream Author (A) 2. The Stream Base class (B), and 3. The Consumer of the stream (C) When B calls the _read() method that A implements, it sets a &#39;reading&#39; flag, so that parallel calls to _read() can be avoided. When A calls stream.push(), B knows that it&#39;s safe to start calling _read() again. If the consumer C is some kind of parser that wants in some cases to pass the source stream off to some other party, but not before &#34;putting back&#34; some bit of previously consumed data (as in the case of Node&#39;s websocket http upgrade implementation). So, stream.unshift() will generally *never* be called by A, but *only* called by C. Prior to this patch, stream.unshift() *also* unset the state.reading flag, meaning that C could indicate the end of a read, and B would dutifully fire off another _read() call to A. This is inappropriate. In the case of fs streams, and other variably-laggy streams that don&#39;t tolerate overlapped _read() calls, this causes big problems. Also, calling stream.shift() after the &#39;end&#39; event did not raise any kind of error, but would cause very strange behavior indeed. Calling it after the EOF chunk was seen, but before the &#39;end&#39; event was fired would also cause weird behavior, and could lead to data being lost, since it would not emit another &#39;readable&#39; event. This change makes it so that: 1. stream.unshift() does *not* set state.reading = false 2. stream.unshift() is allowed up until the &#39;end&#39; event. 3. unshifting onto a EOF-encountered and zero-length (but not yet end-emitted) stream will defer the &#39;end&#39; event until the new data is consumed. 4. pushing onto a EOF-encountered stream is now an error. So, if you read(), you have that single tick to safely unshift() data back into the stream, even if the null chunk was pushed, and the length was 0.
12 years ago
// Check that we didn't get one last unshift.
if (!state.endEmitted && state.length === 0) {
state.endEmitted = true;
stream.readable = false;
stream.emit('end');
}
});
}
}