name : _stream_writable.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. // A bit simpler than readable streams. // Implement an async ._write(chunk, encoding, cb), and it'll handle all // the drain event emission and buffering. 'use strict'; module.exports = Writable; /* <replacement> */ function WriteReq(chunk, encoding, cb) { this.chunk = chunk; this.encoding = encoding; this.callback = cb; this.next = null; } // It seems a linked list but it is not // there will be only 2 of these for each stream function CorkedRequest(state) { var _this = this; this.next = null; this.entry = null; this.finish = function () { onCorkedFinish(_this, state); }; } /* </replacement> */ /*<replacement>*/ var Duplex; /*</replacement>*/ Writable.WritableState = WritableState; /*<replacement>*/ var internalUtil = { deprecate: require('util-deprecate') }; /*</replacement>*/ /*<replacement>*/ var Stream = require('./internal/streams/stream'); /*</replacement>*/ var Buffer = require('buffer').Buffer; var OurUint8Array = (typeof global !== 'undefined' ? global : typeof window !== 'undefined' ? window : typeof self !== 'undefined' ? self : {}).Uint8Array || function () {}; function _uint8ArrayToBuffer(chunk) { return Buffer.from(chunk); } function _isUint8Array(obj) { return Buffer.isBuffer(obj) || obj instanceof OurUint8Array; } var destroyImpl = require('./internal/streams/destroy'); var _require = require('./internal/streams/state'), getHighWaterMark = _require.getHighWaterMark; var _require$codes = require('../errors').codes, ERR_INVALID_ARG_TYPE = _require$codes.ERR_INVALID_ARG_TYPE, ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED, ERR_MULTIPLE_CALLBACK = _require$codes.ERR_MULTIPLE_CALLBACK, ERR_STREAM_CANNOT_PIPE = _require$codes.ERR_STREAM_CANNOT_PIPE, ERR_STREAM_DESTROYED = _require$codes.ERR_STREAM_DESTROYED, ERR_STREAM_NULL_VALUES = _require$codes.ERR_STREAM_NULL_VALUES, ERR_STREAM_WRITE_AFTER_END = _require$codes.ERR_STREAM_WRITE_AFTER_END, ERR_UNKNOWN_ENCODING = _require$codes.ERR_UNKNOWN_ENCODING; var errorOrDestroy = destroyImpl.errorOrDestroy; require('inherits')(Writable, Stream); function nop() {} function WritableState(options, stream, isDuplex) { Duplex = Duplex || require('./_stream_duplex'); options = options || {}; // 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, // e.g. options.readableObjectMode vs. options.writableObjectMode, etc. if (typeof isDuplex !== 'boolean') isDuplex = stream instanceof Duplex; // object stream flag to indicate whether or not this stream // contains buffers or objects. this.objectMode = !!options.objectMode; if (isDuplex) this.objectMode = this.objectMode || !!options.writableObjectMode; // the point at which write() starts returning false // Note: 0 is a valid value, means that we always return false if // the entire buffer is not flushed immediately on write() this.highWaterMark = getHighWaterMark(this, options, 'writableHighWaterMark', isDuplex); // if _final has been called this.finalCalled = false; // drain event flag. this.needDrain = false; // at the start of calling end() this.ending = false; // when end() has been called, and returned this.ended = false; // when 'finish' is emitted this.finished = false; // has it been destroyed this.destroyed = false; // should we decode strings into buffers before passing to _write? // this is here so that some node-core streams can optimize string // handling at a lower level. var noDecode = options.decodeStrings === false; this.decodeStrings = !noDecode; // 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'; // not an actual buffer we keep track of, but a measurement // of how much we're waiting to get pushed to some underlying // socket or file. this.length = 0; // a flag to see when we're in the middle of a write. this.writing = false; // when true all writes will be buffered until .uncork() call this.corked = 0; // 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, because any // actions that shouldn't happen until "later" should generally also // not happen before the first write call. this.sync = true; // a flag to know if we're processing previously buffered items, which // may call the _write() callback in the same tick, so that we don't // end up in an overlapped onwrite situation. this.bufferProcessing = false; // the callback that's passed to _write(chunk,cb) this.onwrite = function (er) { onwrite(stream, er); }; // the callback that the user supplies to write(chunk,encoding,cb) this.writecb = null; // the amount that is being written when _write is called. this.writelen = 0; this.bufferedRequest = null; this.lastBufferedRequest = null; // number of pending user-supplied write callbacks // this must be 0 before 'finish' can be emitted this.pendingcb = 0; // emit prefinish if the only thing we're waiting for is _write cbs // This is relevant for synchronous Transform streams this.prefinished = false; // 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.emitClose !== false; // Should .destroy() be called after 'finish' (and potentially 'end') this.autoDestroy = !!options.autoDestroy; // count buffered requests this.bufferedRequestCount = 0; // allocate the first CorkedRequest, there is always // one allocated and free to use, and we maintain at most two this.corkedRequestsFree = new CorkedRequest(this); } WritableState.prototype.getBuffer = function getBuffer() { var current = this.bufferedRequest; var out = []; while (current) { out.push(current); current = current.next; } return out; }; (function () { try { Object.defineProperty(WritableState.prototype, 'buffer', { get: internalUtil.deprecate(function writableStateBufferGetter() { return this.getBuffer(); }, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' + 'instead.', 'DEP0003') }); } catch (_) {} })(); // Test _writableState for inheritance to account for Duplex streams, // whose prototype chain only points to Readable. var realHasInstance; if (typeof Symbol === 'function' && Symbol.hasInstance && typeof Function.prototype[Symbol.hasInstance] === 'function') { realHasInstance = Function.prototype[Symbol.hasInstance]; Object.defineProperty(Writable, Symbol.hasInstance, { value: function value(object) { if (realHasInstance.call(this, object)) return true; if (this !== Writable) return false; return object && object._writableState instanceof WritableState; } }); } else { realHasInstance = function realHasInstance(object) { return object instanceof this; }; } function Writable(options) { Duplex = Duplex || require('./_stream_duplex'); // Writable ctor is applied to Duplexes, too. // `realHasInstance` is necessary because using plain `instanceof` // would return false, as no `_writableState` property is attached. // Trying to use the custom `instanceof` for Writable here will also break the // Node.js LazyTransform implementation, which has a non-trivial getter for // `_writableState` that would lead to infinite recursion. // Checking for a Stream.Duplex instance is faster here instead of inside // the WritableState constructor, at least with V8 6.5 var isDuplex = this instanceof Duplex; if (!isDuplex && !realHasInstance.call(Writable, this)) return new Writable(options); this._writableState = new WritableState(options, this, isDuplex); // legacy. this.writable = true; if (options) { if (typeof options.write === 'function') this._write = options.write; if (typeof options.writev === 'function') this._writev = options.writev; if (typeof options.destroy === 'function') this._destroy = options.destroy; if (typeof options.final === 'function') this._final = options.final; } Stream.call(this); } // Otherwise people can pipe Writable streams, which is just wrong. Writable.prototype.pipe = function () { errorOrDestroy(this, new ERR_STREAM_CANNOT_PIPE()); }; function writeAfterEnd(stream, cb) { var er = new ERR_STREAM_WRITE_AFTER_END(); // TODO: defer error events consistently everywhere, not just the cb errorOrDestroy(stream, er); process.nextTick(cb, er); } // Checks that a user-supplied chunk is valid, especially for the particular // mode the stream is in. Currently this means that `null` is never accepted // and undefined/non-string values are only allowed in object mode. function validChunk(stream, state, chunk, cb) { var er; if (chunk === null) { er = new ERR_STREAM_NULL_VALUES(); } else if (typeof chunk !== 'string' && !state.objectMode) { er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer'], chunk); } if (er) { errorOrDestroy(stream, er); process.nextTick(cb, er); return false; } return true; } Writable.prototype.write = function (chunk, encoding, cb) { var state = this._writableState; var ret = false; var isBuf = !state.objectMode && _isUint8Array(chunk); if (isBuf && !Buffer.isBuffer(chunk)) { chunk = _uint8ArrayToBuffer(chunk); } if (typeof encoding === 'function') { cb = encoding; encoding = null; } if (isBuf) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding; if (typeof cb !== 'function') cb = nop; if (state.ending) writeAfterEnd(this, cb);else if (isBuf || validChunk(this, state, chunk, cb)) { state.pendingcb++; ret = writeOrBuffer(this, state, isBuf, chunk, encoding, cb); } return ret; }; Writable.prototype.cork = function () { this._writableState.corked++; }; Writable.prototype.uncork = function () { var state = this._writableState; if (state.corked) { state.corked--; if (!state.writing && !state.corked && !state.bufferProcessing && state.bufferedRequest) clearBuffer(this, state); } }; Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) { // node::ParseEncoding() requires lower case. if (typeof encoding === 'string') encoding = encoding.toLowerCase(); if (!(['hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le', 'raw'].indexOf((encoding + '').toLowerCase()) > -1)) throw new ERR_UNKNOWN_ENCODING(encoding); this._writableState.defaultEncoding = encoding; return this; }; Object.defineProperty(Writable.prototype, 'writableBuffer', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._writableState && this._writableState.getBuffer(); } }); function decodeChunk(state, chunk, encoding) { if (!state.objectMode && state.decodeStrings !== false && typeof chunk === 'string') { chunk = Buffer.from(chunk, encoding); } return chunk; } Object.defineProperty(Writable.prototype, 'writableHighWaterMark', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._writableState.highWaterMark; } }); // if we're already writing something, then just put this // in the queue, and wait our turn. Otherwise, call _write // If we return false, then we need a drain event, so set that flag. function writeOrBuffer(stream, state, isBuf, chunk, encoding, cb) { if (!isBuf) { var newChunk = decodeChunk(state, chunk, encoding); if (chunk !== newChunk) { isBuf = true; encoding = 'buffer'; chunk = newChunk; } } var len = state.objectMode ? 1 : chunk.length; state.length += len; var ret = state.length < state.highWaterMark; // we must ensure that previous needDrain will not be reset to false. if (!ret) state.needDrain = true; if (state.writing || state.corked) { var last = state.lastBufferedRequest; state.lastBufferedRequest = { chunk: chunk, encoding: encoding, isBuf: isBuf, callback: cb, next: null }; if (last) { last.next = state.lastBufferedRequest; } else { state.bufferedRequest = state.lastBufferedRequest; } state.bufferedRequestCount += 1; } else { doWrite(stream, state, false, len, chunk, encoding, cb); } return ret; } function doWrite(stream, state, writev, len, chunk, encoding, cb) { state.writelen = len; state.writecb = cb; state.writing = true; state.sync = true; if (state.destroyed) state.onwrite(new ERR_STREAM_DESTROYED('write'));else if (writev) stream._writev(chunk, state.onwrite);else stream._write(chunk, encoding, state.onwrite); state.sync = false; } function onwriteError(stream, state, sync, er, cb) { --state.pendingcb; if (sync) { // defer the callback if we are being called synchronously // to avoid piling up things on the stack process.nextTick(cb, er); // this can emit finish, and it will always happen // after error process.nextTick(finishMaybe, stream, state); stream._writableState.errorEmitted = true; errorOrDestroy(stream, er); } else { // the caller expect this to happen before if // it is async cb(er); stream._writableState.errorEmitted = true; errorOrDestroy(stream, er); // this can emit finish, but finish must // always follow error finishMaybe(stream, state); } } function onwriteStateUpdate(state) { state.writing = false; state.writecb = null; state.length -= state.writelen; state.writelen = 0; } function onwrite(stream, er) { var state = stream._writableState; var sync = state.sync; var cb = state.writecb; if (typeof cb !== 'function') throw new ERR_MULTIPLE_CALLBACK(); onwriteStateUpdate(state); if (er) onwriteError(stream, state, sync, er, cb);else { // Check if we're actually ready to finish, but don't emit yet var finished = needFinish(state) || stream.destroyed; if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) { clearBuffer(stream, state); } if (sync) { process.nextTick(afterWrite, stream, state, finished, cb); } else { afterWrite(stream, state, finished, cb); } } } function afterWrite(stream, state, finished, cb) { if (!finished) onwriteDrain(stream, state); state.pendingcb--; cb(); finishMaybe(stream, state); } // Must force callback to be called on nextTick, so that we don't // emit 'drain' before the write() consumer gets the 'false' return // value, and has a chance to attach a 'drain' listener. function onwriteDrain(stream, state) { if (state.length === 0 && state.needDrain) { state.needDrain = false; stream.emit('drain'); } } // if there's something in the buffer waiting, then process it function clearBuffer(stream, state) { state.bufferProcessing = true; var entry = state.bufferedRequest; if (stream._writev && entry && entry.next) { // Fast case, write everything using _writev() var l = state.bufferedRequestCount; var buffer = new Array(l); var holder = state.corkedRequestsFree; holder.entry = entry; var count = 0; var allBuffers = true; while (entry) { buffer[count] = entry; if (!entry.isBuf) allBuffers = false; entry = entry.next; count += 1; } buffer.allBuffers = allBuffers; doWrite(stream, state, true, state.length, buffer, '', holder.finish); // doWrite is almost always async, defer these to save a bit of time // as the hot path ends with doWrite state.pendingcb++; state.lastBufferedRequest = null; if (holder.next) { state.corkedRequestsFree = holder.next; holder.next = null; } else { state.corkedRequestsFree = new CorkedRequest(state); } state.bufferedRequestCount = 0; } else { // Slow case, write chunks one-by-one while (entry) { var chunk = entry.chunk; var encoding = entry.encoding; var cb = entry.callback; var len = state.objectMode ? 1 : chunk.length; doWrite(stream, state, false, len, chunk, encoding, cb); entry = entry.next; state.bufferedRequestCount--; // if we didn't call the onwrite immediately, then // it means that we need to wait until it does. // also, that means that the chunk and cb are currently // being processed, so move the buffer counter past them. if (state.writing) { break; } } if (entry === null) state.lastBufferedRequest = null; } state.bufferedRequest = entry; state.bufferProcessing = false; } Writable.prototype._write = function (chunk, encoding, cb) { cb(new ERR_METHOD_NOT_IMPLEMENTED('_write()')); }; Writable.prototype._writev = null; Writable.prototype.end = function (chunk, encoding, cb) { var state = this._writableState; if (typeof chunk === 'function') { cb = chunk; chunk = null; encoding = null; } else if (typeof encoding === 'function') { cb = encoding; encoding = null; } if (chunk !== null && chunk !== undefined) this.write(chunk, encoding); // .end() fully uncorks if (state.corked) { state.corked = 1; this.uncork(); } // ignore unnecessary end() calls. if (!state.ending) endWritable(this, state, cb); return this; }; Object.defineProperty(Writable.prototype, 'writableLength', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { return this._writableState.length; } }); function needFinish(state) { return state.ending && state.length === 0 && state.bufferedRequest === null && !state.finished && !state.writing; } function callFinal(stream, state) { stream._final(function (err) { state.pendingcb--; if (err) { errorOrDestroy(stream, err); } state.prefinished = true; stream.emit('prefinish'); finishMaybe(stream, state); }); } function prefinish(stream, state) { if (!state.prefinished && !state.finalCalled) { if (typeof stream._final === 'function' && !state.destroyed) { state.pendingcb++; state.finalCalled = true; process.nextTick(callFinal, stream, state); } else { state.prefinished = true; stream.emit('prefinish'); } } } function finishMaybe(stream, state) { var need = needFinish(state); if (need) { prefinish(stream, state); if (state.pendingcb === 0) { state.finished = true; stream.emit('finish'); if (state.autoDestroy) { // In case of duplex streams we need a way to detect // if the readable side is ready for autoDestroy as well var rState = stream._readableState; if (!rState || rState.autoDestroy && rState.endEmitted) { stream.destroy(); } } } } return need; } function endWritable(stream, state, cb) { state.ending = true; finishMaybe(stream, state); if (cb) { if (state.finished) process.nextTick(cb);else stream.once('finish', cb); } state.ended = true; stream.writable = false; } function onCorkedFinish(corkReq, state, err) { var entry = corkReq.entry; corkReq.entry = null; while (entry) { var cb = entry.callback; state.pendingcb--; cb(err); entry = entry.next; } // reuse the free corkReq. state.corkedRequestsFree.next = corkReq; } Object.defineProperty(Writable.prototype, 'destroyed', { // making it explicit this property is not enumerable // because otherwise some prototype manipulation in // userland will fail enumerable: false, get: function get() { if (this._writableState === undefined) { return false; } return this._writableState.destroyed; }, set: function set(value) { // we ignore the value if the stream // has not been initialized yet if (!this._writableState) { return; } // backward compatibility, the user is explicitly // managing destroyed this._writableState.destroyed = value; } }); Writable.prototype.destroy = destroyImpl.destroy; Writable.prototype._undestroy = destroyImpl.undestroy; Writable.prototype._destroy = function (err, cb) { cb(err); };