time-to-botec

_stream_writable.js (20317B)

---

 // 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';
 
 /*<replacement>*/
 
 var pna = require('process-nextick-args');
 /*</replacement>*/
 
 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 asyncWrite = !process.browser && ['v0.10', 'v0.9.'].indexOf(process.version.slice(0, 5)) > -1 ? setImmediate : pna.nextTick;
 /*</replacement>*/
 
 /*<replacement>*/
 var Duplex;
 /*</replacement>*/
 
 Writable.WritableState = WritableState;
 
 /*<replacement>*/
 var util = Object.create(require('core-util-is'));
 util.inherits = require('inherits');
 /*</replacement>*/
 
 /*<replacement>*/
 var internalUtil = {
   deprecate: require('util-deprecate')
 };
 /*</replacement>*/
 
 /*<replacement>*/
 var Stream = require('./internal/streams/stream');
 /*</replacement>*/
 
 /*<replacement>*/
 
 var Buffer = require('safe-buffer').Buffer;
 var OurUint8Array = global.Uint8Array || function () {};
 function _uint8ArrayToBuffer(chunk) {
   return Buffer.from(chunk);
 }
 function _isUint8Array(obj) {
   return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
 }
 
 /*</replacement>*/
 
 var destroyImpl = require('./internal/streams/destroy');
 
 util.inherits(Writable, Stream);
 
 function nop() {}
 
 function WritableState(options, stream) {
   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.
   // These options can be provided separately as readableXXX and writableXXX.
   var 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()
   var hwm = options.highWaterMark;
   var writableHwm = options.writableHighWaterMark;
   var defaultHwm = this.objectMode ? 16 : 16 * 1024;
 
   if (hwm || hwm === 0) this.highWaterMark = hwm;else if (isDuplex && (writableHwm || writableHwm === 0)) this.highWaterMark = writableHwm;else this.highWaterMark = defaultHwm;
 
   // cast to ints.
   this.highWaterMark = Math.floor(this.highWaterMark);
 
   // 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;
 
   // 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 () {
         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 (object) {
       if (realHasInstance.call(this, object)) return true;
       if (this !== Writable) return false;
 
       return object && object._writableState instanceof WritableState;
     }
   });
 } else {
   realHasInstance = function (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.
   if (!realHasInstance.call(Writable, this) && !(this instanceof Duplex)) {
     return new Writable(options);
   }
 
   this._writableState = new WritableState(options, this);
 
   // 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 () {
   this.emit('error', new Error('Cannot pipe, not readable'));
 };
 
 function writeAfterEnd(stream, cb) {
   var er = new Error('write after end');
   // TODO: defer error events consistently everywhere, not just the cb
   stream.emit('error', er);
   pna.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 valid = true;
   var er = false;
 
   if (chunk === null) {
     er = new TypeError('May not write null values to stream');
   } else if (typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
     er = new TypeError('Invalid non-string/buffer chunk');
   }
   if (er) {
     stream.emit('error', er);
     pna.nextTick(cb, er);
     valid = false;
   }
   return valid;
 }
 
 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.ended) 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 () {
   var state = this._writableState;
 
   state.corked++;
 };
 
 Writable.prototype.uncork = function () {
   var state = this._writableState;
 
   if (state.corked) {
     state.corked--;
 
     if (!state.writing && !state.corked && !state.finished && !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 TypeError('Unknown encoding: ' + encoding);
   this._writableState.defaultEncoding = encoding;
   return this;
 };
 
 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 () {
     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 (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
     pna.nextTick(cb, er);
     // this can emit finish, and it will always happen
     // after error
     pna.nextTick(finishMaybe, stream, state);
     stream._writableState.errorEmitted = true;
     stream.emit('error', er);
   } else {
     // the caller expect this to happen before if
     // it is async
     cb(er);
     stream._writableState.errorEmitted = true;
     stream.emit('error', 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;
 
   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);
 
     if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) {
       clearBuffer(stream, state);
     }
 
     if (sync) {
       /*<replacement>*/
       asyncWrite(afterWrite, stream, state, finished, cb);
       /*</replacement>*/
     } 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 Error('_write() is not implemented'));
 };
 
 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 && !state.finished) endWritable(this, state, cb);
 };
 
 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) {
       stream.emit('error', 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.pendingcb++;
       state.finalCalled = true;
       pna.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');
     }
   }
   return need;
 }
 
 function endWritable(stream, state, cb) {
   state.ending = true;
   finishMaybe(stream, state);
   if (cb) {
     if (state.finished) pna.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;
   }
   if (state.corkedRequestsFree) {
     state.corkedRequestsFree.next = corkReq;
   } else {
     state.corkedRequestsFree = corkReq;
   }
 }
 
 Object.defineProperty(Writable.prototype, 'destroyed', {
   get: function () {
     if (this._writableState === undefined) {
       return false;
     }
     return this._writableState.destroyed;
   },
   set: function (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) {
   this.end();
   cb(err);
 };