lts/lib/_stream_readable.js
// 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.
'use strict';
const {
ArrayIsArray,
NumberIsInteger,
NumberIsNaN,
ObjectDefineProperties,
ObjectSetPrototypeOf,
Set,
SymbolAsyncIterator,
Symbol
} = primordials;
module.exports = Readable;
Readable.ReadableState = ReadableState;
const EE = require('events');
const Stream = require('stream');
const { Buffer } = require('buffer');
const debug = require('internal/util/debuglog').debuglog('stream');
const BufferList = require('internal/streams/buffer_list');
const destroyImpl = require('internal/streams/destroy');
const {
getHighWaterMark,
getDefaultHighWaterMark
} = require('internal/streams/state');
const {
ERR_INVALID_ARG_TYPE,
ERR_STREAM_PUSH_AFTER_EOF,
ERR_METHOD_NOT_IMPLEMENTED,
ERR_STREAM_UNSHIFT_AFTER_END_EVENT
} = require('internal/errors').codes;
const kPaused = Symbol('kPaused');
// Lazy loaded to improve the startup performance.
let StringDecoder;
let createReadableStreamAsyncIterator;
let from;
ObjectSetPrototypeOf(Readable.prototype, Stream.prototype);
ObjectSetPrototypeOf(Readable, Stream);
const { errorOrDestroy } = destroyImpl;
const kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];
function prependListener(emitter, event, fn) {
// Sadly this is not cacheable as some libraries bundle their own
// event emitter implementation with them.
if (typeof emitter.prependListener === 'function')
return emitter.prependListener(event, fn);
// This is a hack to make sure that our error handler is attached before any
// userland ones. NEVER DO THIS. This is here only because this code needs
// to continue to work with older versions of Node.js that do not include
// the prependListener() method. The goal is to eventually remove this hack.
if (!emitter._events || !emitter._events[event])
emitter.on(event, fn);
else if (ArrayIsArray(emitter._events[event]))
emitter._events[event].unshift(fn);
else
emitter._events[event] = [fn, emitter._events[event]];
}
function ReadableState(options, stream, isDuplex) {
// Duplex streams are both readable and writable, but share
// the same options object.
// However, some cases require setting options to different
// values for the readable and the writable sides of the duplex stream.
// These options can be provided separately as readableXXX and writableXXX.
if (typeof isDuplex !== 'boolean')
isDuplex = stream instanceof Stream.Duplex;
// 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 && options.objectMode);
if (isDuplex)
this.objectMode = this.objectMode ||
!!(options && options.readableObjectMode);
// 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"
this.highWaterMark = options ?
getHighWaterMark(this, options, 'readableHighWaterMark', isDuplex) :
getDefaultHighWaterMark(false);
// A linked list is used to store data chunks instead of an array because the
// linked list can remove elements from the beginning faster than
// array.shift()
this.buffer = new BufferList();
this.length = 0;
this.pipes = null;
this.pipesCount = 0;
this.flowing = null;
this.ended = false;
this.endEmitted = false;
this.reading = false;
// A flag to be able to tell if the event 'readable'/'data' is emitted
// immediately, or on a later tick. We set this to true at first, because
// any actions that shouldn't happen until "later" should generally also
// not happen before the first read 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;
this.resumeScheduled = false;
this[kPaused] = null;
// Should close be emitted on destroy. Defaults to true.
this.emitClose = !options || options.emitClose !== false;
// Should .destroy() be called after 'end' (and potentially 'finish')
this.autoDestroy = !!(options && options.autoDestroy);
// Has it been destroyed
this.destroyed = false;
// 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 && options.defaultEncoding) || 'utf8';
// Ref the piped dest which we need a drain event on it
// type: null | Writable | Set<Writable>
this.awaitDrainWriters = null;
this.multiAwaitDrain = false;
// If true, a maybeReadMore has been scheduled
this.readingMore = false;
this.decoder = null;
this.encoding = null;
if (options && 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);
// Checking for a Stream.Duplex instance is faster here instead of inside
// the ReadableState constructor, at least with V8 6.5
const isDuplex = this instanceof Stream.Duplex;
this._readableState = new ReadableState(options, this, isDuplex);
// legacy
this.readable = true;
if (options) {
if (typeof options.read === 'function')
this._read = options.read;
if (typeof options.destroy === 'function')
this._destroy = options.destroy;
}
Stream.call(this, options);
}
Readable.prototype.destroy = destroyImpl.destroy;
Readable.prototype._undestroy = destroyImpl.undestroy;
Readable.prototype._destroy = function(err, cb) {
cb(err);
};
Readable.prototype[EE.captureRejectionSymbol] = function(err) {
// TODO(mcollina): remove the destroyed if once errorEmitted lands in
// Readable.
if (!this.destroyed) {
this.destroy(err);
}
};
// 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) {
return readableAddChunk(this, chunk, encoding, false);
};
// Unshift should *always* be something directly out of read()
Readable.prototype.unshift = function(chunk, encoding) {
return readableAddChunk(this, chunk, encoding, true);
};
function readableAddChunk(stream, chunk, encoding, addToFront) {
debug('readableAddChunk', chunk);
const state = stream._readableState;
let err;
if (!state.objectMode) {
if (typeof chunk === 'string') {
encoding = encoding || state.defaultEncoding;
if (addToFront && state.encoding && state.encoding !== encoding) {
// When unshifting, if state.encoding is set, we have to save
// the string in the BufferList with the state encoding
chunk = Buffer.from(chunk, encoding).toString(state.encoding);
} else if (encoding !== state.encoding) {
chunk = Buffer.from(chunk, encoding);
encoding = '';
}
} else if (chunk instanceof Buffer) {
encoding = '';
} else if (Stream._isUint8Array(chunk)) {
chunk = Stream._uint8ArrayToBuffer(chunk);
encoding = '';
} else if (chunk != null) {
err = new ERR_INVALID_ARG_TYPE(
'chunk', ['string', 'Buffer', 'Uint8Array'], chunk);
}
}
if (err) {
errorOrDestroy(stream, err);
} else if (chunk === null) {
state.reading = false;
onEofChunk(stream, state);
} else if (state.objectMode || (chunk && chunk.length > 0)) {
if (addToFront) {
if (state.endEmitted)
errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
else
addChunk(stream, state, chunk, true);
} else if (state.ended) {
errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
} else if (state.destroyed) {
return false;
} else {
state.reading = false;
if (state.decoder && !encoding) {
chunk = state.decoder.write(chunk);
if (state.objectMode || chunk.length !== 0)
addChunk(stream, state, chunk, false);
else
maybeReadMore(stream, state);
} else {
addChunk(stream, state, chunk, false);
}
}
} else if (!addToFront) {
state.reading = false;
maybeReadMore(stream, state);
}
// We can push more data if we are below the highWaterMark.
// 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.
return !state.ended &&
(state.length < state.highWaterMark || state.length === 0);
}
function addChunk(stream, state, chunk, addToFront) {
if (state.flowing && state.length === 0 && !state.sync) {
// Use the guard to avoid creating `Set()` repeatedly
// when we have multiple pipes.
if (state.multiAwaitDrain) {
state.awaitDrainWriters.clear();
} else {
state.awaitDrainWriters = null;
}
stream.emit('data', chunk);
} else {
// Update the buffer info.
state.length += state.objectMode ? 1 : chunk.length;
if (addToFront)
state.buffer.unshift(chunk);
else
state.buffer.push(chunk);
if (state.needReadable)
emitReadable(stream);
}
maybeReadMore(stream, state);
}
Readable.prototype.isPaused = function() {
const state = this._readableState;
return state[kPaused] === true || state.flowing === false;
};
// Backwards compatibility.
Readable.prototype.setEncoding = function(enc) {
if (!StringDecoder)
StringDecoder = require('string_decoder').StringDecoder;
const decoder = new StringDecoder(enc);
this._readableState.decoder = decoder;
// If setEncoding(null), decoder.encoding equals utf8
this._readableState.encoding = this._readableState.decoder.encoding;
const buffer = this._readableState.buffer;
// Iterate over current buffer to convert already stored Buffers:
let content = '';
for (const data of buffer) {
content += decoder.write(data);
}
buffer.clear();
if (content !== '')
buffer.push(content);
this._readableState.length = content.length;
return this;
};
// Don't raise the hwm > 1GB
const MAX_HWM = 0x40000000;
function computeNewHighWaterMark(n) {
if (n >= MAX_HWM) {
// TODO(ronag): Throw ERR_VALUE_OUT_OF_RANGE.
n = MAX_HWM;
} else {
// Get the next highest power of 2 to prevent increasing hwm excessively in
// tiny amounts
n--;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
n++;
}
return n;
}
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function howMuchToRead(n, state) {
if (n <= 0 || (state.length === 0 && state.ended))
return 0;
if (state.objectMode)
return 1;
if (NumberIsNaN(n)) {
// Only flow one buffer at a time
if (state.flowing && state.length)
return state.buffer.first().length;
return state.length;
}
if (n <= state.length)
return n;
return state.ended ? state.length : 0;
}
// You can override either this method, or the async _read(n) below.
Readable.prototype.read = function(n) {
debug('read', n);
// Same as parseInt(undefined, 10), however V8 7.3 performance regressed
// in this scenario, so we are doing it manually.
if (n === undefined) {
n = NaN;
} else if (!NumberIsInteger(n)) {
n = parseInt(n, 10);
}
const state = this._readableState;
const nOrig = n;
// If we're asking for more than the current hwm, then raise the hwm.
if (n > state.highWaterMark)
state.highWaterMark = computeNewHighWaterMark(n);
if (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.highWaterMark !== 0 ?
state.length >= state.highWaterMark :
state.length > 0) ||
state.ended)) {
debug('read: emitReadable', state.length, state.ended);
if (state.length === 0 && state.ended)
endReadable(this);
else
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;
debug('need readable', doRead);
// If we currently have less than the highWaterMark, then also read some
if (state.length === 0 || state.length - n < state.highWaterMark) {
doRead = true;
debug('length less than watermark', doRead);
}
// However, if we've ended, then there's no point, if we're already
// reading, then it's unnecessary, and if we're destroyed, then it's
// not allowed.
if (state.ended || state.reading || state.destroyed) {
doRead = false;
debug('reading or ended', doRead);
} else if (doRead) {
debug('do read');
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 pushed data synchronously, then `reading` will be false,
// and we need to re-evaluate how much data we can return to the user.
if (!state.reading)
n = howMuchToRead(nOrig, state);
}
var ret;
if (n > 0)
ret = fromList(n, state);
else
ret = null;
if (ret === null) {
state.needReadable = state.length <= state.highWaterMark;
n = 0;
} else {
state.length -= n;
if (state.multiAwaitDrain) {
state.awaitDrainWriters.clear();
} else {
state.awaitDrainWriters = null;
}
}
if (state.length === 0) {
// If we have nothing in the buffer, then we want to know
// as soon as we *do* get something into the buffer.
if (!state.ended)
state.needReadable = true;
// If we tried to read() past the EOF, then emit end on the next tick.
if (nOrig !== n && state.ended)
endReadable(this);
}
if (ret !== null)
this.emit('data', ret);
return ret;
};
function onEofChunk(stream, state) {
debug('onEofChunk');
if (state.ended) return;
if (state.decoder) {
var chunk = state.decoder.end();
if (chunk && chunk.length) {
state.buffer.push(chunk);
state.length += state.objectMode ? 1 : chunk.length;
}
}
state.ended = true;
if (state.sync) {
// If we are sync, wait until next tick to emit the data.
// Otherwise we risk emitting data in the flow()
// the readable code triggers during a read() call
emitReadable(stream);
} else {
// Emit 'readable' now to make sure it gets picked up.
state.needReadable = false;
state.emittedReadable = true;
// We have to emit readable now that we are EOF. Modules
// in the ecosystem (e.g. dicer) rely on this event being sync.
emitReadable_(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) {
const state = stream._readableState;
debug('emitReadable', state.needReadable, state.emittedReadable);
state.needReadable = false;
if (!state.emittedReadable) {
debug('emitReadable', state.flowing);
state.emittedReadable = true;
process.nextTick(emitReadable_, stream);
}
}
function emitReadable_(stream) {
const state = stream._readableState;
debug('emitReadable_', state.destroyed, state.length, state.ended);
if (!state.destroyed && (state.length || state.ended)) {
stream.emit('readable');
state.emittedReadable = false;
}
// The stream needs another readable event if
// 1. It is not flowing, as the flow mechanism will take
// care of it.
// 2. It is not ended.
// 3. It is below the highWaterMark, so we can schedule
// another readable later.
state.needReadable =
!state.flowing &&
!state.ended &&
state.length <= state.highWaterMark;
flow(stream);
}
// 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(maybeReadMore_, stream, state);
}
}
function maybeReadMore_(stream, state) {
// Attempt to read more data if we should.
//
// The conditions for reading more data are (one of):
// - Not enough data buffered (state.length < state.highWaterMark). The loop
// is responsible for filling the buffer with enough data if such data
// is available. If highWaterMark is 0 and we are not in the flowing mode
// we should _not_ attempt to buffer any extra data. We'll get more data
// when the stream consumer calls read() instead.
// - No data in the buffer, and the stream is in flowing mode. In this mode
// the loop below is responsible for ensuring read() is called. Failing to
// call read here would abort the flow and there's no other mechanism for
// continuing the flow if the stream consumer has just subscribed to the
// 'data' event.
//
// In addition to the above conditions to keep reading data, the following
// conditions prevent the data from being read:
// - The stream has ended (state.ended).
// - There is already a pending 'read' operation (state.reading). This is a
// case where the the stream has called the implementation defined _read()
// method, but they are processing the call asynchronously and have _not_
// called push() with new data. In this case we skip performing more
// read()s. The execution ends in this method again after the _read() ends
// up calling push() with more data.
while (!state.reading && !state.ended &&
(state.length < state.highWaterMark ||
(state.flowing && state.length === 0))) {
const len = state.length;
debug('maybeReadMore read 0');
stream.read(0);
if (len === state.length)
// Didn't get any data, stop spinning.
break;
}
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) {
errorOrDestroy(this, new ERR_METHOD_NOT_IMPLEMENTED('_read()'));
};
Readable.prototype.pipe = function(dest, pipeOpts) {
const src = this;
const state = this._readableState;
if (state.pipesCount === 1) {
if (!state.multiAwaitDrain) {
state.multiAwaitDrain = true;
state.awaitDrainWriters = new Set(
state.awaitDrainWriters ? [state.awaitDrainWriters] : []
);
}
}
switch (state.pipesCount) {
case 0:
state.pipes = dest;
break;
case 1:
state.pipes = [state.pipes, dest];
break;
default:
state.pipes.push(dest);
break;
}
state.pipesCount += 1;
debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);
const doEnd = (!pipeOpts || pipeOpts.end !== false) &&
dest !== process.stdout &&
dest !== process.stderr;
const endFn = doEnd ? onend : unpipe;
if (state.endEmitted)
process.nextTick(endFn);
else
src.once('end', endFn);
dest.on('unpipe', onunpipe);
function onunpipe(readable, unpipeInfo) {
debug('onunpipe');
if (readable === src) {
if (unpipeInfo && unpipeInfo.hasUnpiped === false) {
unpipeInfo.hasUnpiped = true;
cleanup();
}
}
}
function onend() {
debug('onend');
dest.end();
}
let ondrain;
var cleanedUp = false;
function cleanup() {
debug('cleanup');
// Cleanup event handlers once the pipe is broken
dest.removeListener('close', onclose);
dest.removeListener('finish', onfinish);
if (ondrain) {
dest.removeListener('drain', ondrain);
}
dest.removeListener('error', onerror);
dest.removeListener('unpipe', onunpipe);
src.removeListener('end', onend);
src.removeListener('end', unpipe);
src.removeListener('data', ondata);
cleanedUp = true;
// 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 (ondrain && state.awaitDrainWriters &&
(!dest._writableState || dest._writableState.needDrain))
ondrain();
}
src.on('data', ondata);
function ondata(chunk) {
debug('ondata');
const ret = dest.write(chunk);
debug('dest.write', ret);
if (ret === false) {
// If the user unpiped during `dest.write()`, it is possible
// to get stuck in a permanently paused state if that write
// also returned false.
// => Check whether `dest` is still a piping destination.
if (!cleanedUp) {
if (state.pipesCount === 1 && state.pipes === dest) {
debug('false write response, pause', 0);
state.awaitDrainWriters = dest;
state.multiAwaitDrain = false;
} else if (state.pipesCount > 1 && state.pipes.includes(dest)) {
debug('false write response, pause', state.awaitDrainWriters.size);
state.awaitDrainWriters.add(dest);
}
src.pause();
}
if (!ondrain) {
// 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.
ondrain = pipeOnDrain(src, dest);
dest.on('drain', ondrain);
}
}
}
// If the dest has an error, then stop piping into it.
// However, don't suppress the throwing behavior for this.
function onerror(er) {
debug('onerror', er);
unpipe();
dest.removeListener('error', onerror);
if (EE.listenerCount(dest, 'error') === 0)
errorOrDestroy(dest, er);
}
// Make sure our error handler is attached before userland ones.
prependListener(dest, '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() {
debug('onfinish');
dest.removeListener('close', onclose);
unpipe();
}
dest.once('finish', onfinish);
function unpipe() {
debug('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) {
debug('pipe resume');
src.resume();
}
return dest;
};
function pipeOnDrain(src, dest) {
return function pipeOnDrainFunctionResult() {
const state = src._readableState;
// `ondrain` will call directly,
// `this` maybe not a reference to dest,
// so we use the real dest here.
if (state.awaitDrainWriters === dest) {
debug('pipeOnDrain', 1);
state.awaitDrainWriters = null;
} else if (state.multiAwaitDrain) {
debug('pipeOnDrain', state.awaitDrainWriters.size);
state.awaitDrainWriters.delete(dest);
}
if ((!state.awaitDrainWriters || state.awaitDrainWriters.size === 0) &&
EE.listenerCount(src, 'data')) {
state.flowing = true;
flow(src);
}
};
}
Readable.prototype.unpipe = function(dest) {
const state = this._readableState;
const unpipeInfo = { hasUnpiped: false };
// 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;
state.flowing = false;
if (dest)
dest.emit('unpipe', this, unpipeInfo);
return this;
}
// Slow case with multiple pipe destinations.
if (!dest) {
// remove all.
var dests = state.pipes;
var len = state.pipesCount;
state.pipes = null;
state.pipesCount = 0;
state.flowing = false;
for (var i = 0; i < len; i++)
dests[i].emit('unpipe', this, { hasUnpiped: false });
return this;
}
// Try to find the right one.
const index = state.pipes.indexOf(dest);
if (index === -1)
return this;
state.pipes.splice(index, 1);
state.pipesCount -= 1;
if (state.pipesCount === 1)
state.pipes = state.pipes[0];
dest.emit('unpipe', this, unpipeInfo);
return this;
};
// Set up data events if they are asked for
// Ensure readable listeners eventually get something
Readable.prototype.on = function(ev, fn) {
const res = Stream.prototype.on.call(this, ev, fn);
const state = this._readableState;
if (ev === 'data') {
// Update readableListening so that resume() may be a no-op
// a few lines down. This is needed to support once('readable').
state.readableListening = this.listenerCount('readable') > 0;
// Try start flowing on next tick if stream isn't explicitly paused
if (state.flowing !== false)
this.resume();
} else if (ev === 'readable') {
if (!state.endEmitted && !state.readableListening) {
state.readableListening = state.needReadable = true;
state.flowing = false;
state.emittedReadable = false;
debug('on readable', state.length, state.reading);
if (state.length) {
emitReadable(this);
} else if (!state.reading) {
process.nextTick(nReadingNextTick, this);
}
}
}
return res;
};
Readable.prototype.addListener = Readable.prototype.on;
Readable.prototype.removeListener = function(ev, fn) {
const res = Stream.prototype.removeListener.call(this, ev, fn);
if (ev === 'readable') {
// We need to check if there is someone still listening to
// readable and reset the state. However this needs to happen
// after readable has been emitted but before I/O (nextTick) to
// support once('readable', fn) cycles. This means that calling
// resume within the same tick will have no
// effect.
process.nextTick(updateReadableListening, this);
}
return res;
};
Readable.prototype.off = Readable.prototype.removeListener;
Readable.prototype.removeAllListeners = function(ev) {
const res = Stream.prototype.removeAllListeners.apply(this, arguments);
if (ev === 'readable' || ev === undefined) {
// We need to check if there is someone still listening to
// readable and reset the state. However this needs to happen
// after readable has been emitted but before I/O (nextTick) to
// support once('readable', fn) cycles. This means that calling
// resume within the same tick will have no
// effect.
process.nextTick(updateReadableListening, this);
}
return res;
};
function updateReadableListening(self) {
const state = self._readableState;
state.readableListening = self.listenerCount('readable') > 0;
if (state.resumeScheduled && state[kPaused] === false) {
// Flowing needs to be set to true now, otherwise
// the upcoming resume will not flow.
state.flowing = true;
// Crude way to check if we should resume
} else if (self.listenerCount('data') > 0) {
self.resume();
} else if (!state.readableListening) {
state.flowing = null;
}
}
function nReadingNextTick(self) {
debug('readable nexttick read 0');
self.read(0);
}
// 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() {
const state = this._readableState;
if (!state.flowing) {
debug('resume');
// We flow only if there is no one listening
// for readable, but we still have to call
// resume()
state.flowing = !state.readableListening;
resume(this, state);
}
state[kPaused] = false;
return this;
};
function resume(stream, state) {
if (!state.resumeScheduled) {
state.resumeScheduled = true;
process.nextTick(resume_, stream, state);
}
}
function resume_(stream, state) {
debug('resume', state.reading);
if (!state.reading) {
stream.read(0);
}
state.resumeScheduled = false;
stream.emit('resume');
flow(stream);
if (state.flowing && !state.reading)
stream.read(0);
}
Readable.prototype.pause = function() {
debug('call pause flowing=%j', this._readableState.flowing);
if (this._readableState.flowing !== false) {
debug('pause');
this._readableState.flowing = false;
this.emit('pause');
}
this._readableState[kPaused] = true;
return this;
};
function flow(stream) {
const state = stream._readableState;
debug('flow', state.flowing);
while (state.flowing && stream.read() !== null);
}
// 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) {
const state = this._readableState;
var paused = false;
stream.on('end', () => {
debug('wrapped end');
if (state.decoder && !state.ended) {
var chunk = state.decoder.end();
if (chunk && chunk.length)
this.push(chunk);
}
this.push(null);
});
stream.on('data', (chunk) => {
debug('wrapped data');
if (state.decoder)
chunk = state.decoder.write(chunk);
// Don't skip over falsy values in objectMode
if (state.objectMode && (chunk === null || chunk === undefined))
return;
else if (!state.objectMode && (!chunk || !chunk.length))
return;
const ret = this.push(chunk);
if (!ret) {
paused = true;
stream.pause();
}
});
// Proxy all the other methods. Important when wrapping filters and duplexes.
for (const i in stream) {
if (this[i] === undefined && typeof stream[i] === 'function') {
this[i] = function methodWrap(method) {
return function methodWrapReturnFunction() {
return stream[method].apply(stream, arguments);
};
}(i);
}
}
// Proxy certain important events.
for (const kProxyEvent of kProxyEvents) {
stream.on(kProxyEvent, this.emit.bind(this, kProxyEvent));
}
// When we try to consume some more bytes, simply unpause the
// underlying stream.
this._read = (n) => {
debug('wrapped _read', n);
if (paused) {
paused = false;
stream.resume();
}
};
return this;
};
Readable.prototype[SymbolAsyncIterator] = function() {
if (createReadableStreamAsyncIterator === undefined) {
createReadableStreamAsyncIterator =
require('internal/streams/async_iterator');
}
return createReadableStreamAsyncIterator(this);
};
// Making it explicit these properties are not enumerable
// because otherwise some prototype manipulation in
// userland will fail
ObjectDefineProperties(Readable.prototype, {
readableHighWaterMark: {
enumerable: false,
get: function() {
return this._readableState.highWaterMark;
}
},
readableBuffer: {
enumerable: false,
get: function() {
return this._readableState && this._readableState.buffer;
}
},
readableFlowing: {
enumerable: false,
get: function() {
return this._readableState.flowing;
},
set: function(state) {
if (this._readableState) {
this._readableState.flowing = state;
}
}
},
readableLength: {
enumerable: false,
get() {
return this._readableState.length;
}
},
readableObjectMode: {
enumerable: false,
get() {
return this._readableState ? this._readableState.objectMode : false;
}
},
readableEncoding: {
enumerable: false,
get() {
return this._readableState ? this._readableState.encoding : null;
}
},
destroyed: {
enumerable: false,
get() {
if (this._readableState === undefined) {
return false;
}
return this._readableState.destroyed;
},
set(value) {
// We ignore the value if the stream
// has not been initialized yet
if (!this._readableState) {
return;
}
// Backward compatibility, the user is explicitly
// managing destroyed
this._readableState.destroyed = value;
}
},
readableEnded: {
enumerable: false,
get() {
return this._readableState ? this._readableState.endEmitted : false;
}
},
paused: {
get() {
return this[kPaused] !== false;
},
set(value) {
this[kPaused] = !!value;
}
}
});
// 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.
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function fromList(n, state) {
// nothing buffered
if (state.length === 0)
return null;
var ret;
if (state.objectMode)
ret = state.buffer.shift();
else if (!n || n >= state.length) {
// Read it all, truncate the list
if (state.decoder)
ret = state.buffer.join('');
else if (state.buffer.length === 1)
ret = state.buffer.first();
else
ret = state.buffer.concat(state.length);
state.buffer.clear();
} else {
// read part of list
ret = state.buffer.consume(n, state.decoder);
}
return ret;
}
function endReadable(stream) {
const state = stream._readableState;
debug('endReadable', state.endEmitted);
if (!state.endEmitted) {
state.ended = true;
process.nextTick(endReadableNT, state, stream);
}
}
function endReadableNT(state, stream) {
debug('endReadableNT', state.endEmitted, state.length);
// Check that we didn't get one last unshift.
if (!state.endEmitted && state.length === 0) {
state.endEmitted = true;
stream.readable = false;
stream.emit('end');
if (state.autoDestroy) {
// In case of duplex streams we need a way to detect
// if the writable side is ready for autoDestroy as well
const wState = stream._writableState;
if (!wState || (wState.autoDestroy && wState.finished)) {
stream.destroy();
}
}
}
}
Readable.from = function(iterable, opts) {
if (from === undefined) {
from = require('internal/streams/from');
}
return from(Readable, iterable, opts);
};