| // 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, |
| Boolean, |
| 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 = []; |
| 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; |
| |
| // True if the error was already emitted and should not be thrown again |
| this.errorEmitted = false; |
| |
| // 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 !== false; |
| |
| // Has it been destroyed |
| this.destroyed = false; |
| |
| // Indicates whether the stream has errored. |
| this.errored = false; |
| |
| // Indicates whether the stream has finished destroying. |
| this.closed = 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); |
| |
| 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) { |
| 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; |
| else |
| 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.pipes.length === 1) { |
| if (!state.multiAwaitDrain) { |
| state.multiAwaitDrain = true; |
| state.awaitDrainWriters = new Set( |
| state.awaitDrainWriters ? [state.awaitDrainWriters] : [] |
| ); |
| } |
| } |
| |
| state.pipes.push(dest); |
| debug('pipe count=%d opts=%j', state.pipes.length, 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.pipes.length === 1 && state.pipes[0] === dest) { |
| debug('false write response, pause', 0); |
| state.awaitDrainWriters = dest; |
| state.multiAwaitDrain = false; |
| } else if (state.pipes.length > 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) { |
| const s = dest._writableState || dest._readableState; |
| if (s && !s.errorEmitted) { |
| // User incorrectly emitted 'error' directly on the stream. |
| errorOrDestroy(dest, er); |
| } else { |
| dest.emit('error', 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.pipes.length === 0) |
| return this; |
| |
| if (!dest) { |
| // remove all. |
| var dests = state.pipes; |
| state.pipes = []; |
| state.flowing = false; |
| |
| for (const dest of dests) |
| dest.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); |
| if (state.pipes.length === 0) |
| state.flowing = false; |
| |
| 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, { |
| readable: { |
| get() { |
| const r = this._readableState; |
| if (!r) return false; |
| if (r.readable !== undefined) return r.readable && !r.endEmitted; |
| return Boolean(!r.destroyed && !r.errorEmitted && !r.endEmitted); |
| }, |
| set(val) { |
| // Backwards compat. |
| if (this._readableState) { |
| this._readableState.readable = !!val; |
| } |
| } |
| }, |
| |
| 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; |
| } |
| }, |
| |
| // Legacy getter for `pipesCount` |
| pipesCount: { |
| get() { |
| return this.pipes.length; |
| } |
| }, |
| |
| 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.errorEmitted && !state.endEmitted && state.length === 0) { |
| state.endEmitted = true; |
| 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); |
| }; |