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477 lines
13 KiB
477 lines
13 KiB
// Copyright Joyent, Inc. and other Node contributors. |
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// |
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// Permission is hereby granted, free of charge, to any person obtaining a |
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// copy of this software and associated documentation files (the |
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// "Software"), to deal in the Software without restriction, including |
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// without limitation the rights to use, copy, modify, merge, publish, |
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// distribute, sublicense, and/or sell copies of the Software, and to permit |
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// persons to whom the Software is furnished to do so, subject to the |
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// following conditions: |
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// |
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// The above copyright notice and this permission notice shall be included |
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// in all copies or substantial portions of the Software. |
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// |
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN |
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// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, |
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// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE |
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// USE OR OTHER DEALINGS IN THE SOFTWARE. |
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// A bit simpler than readable streams. |
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// Implement an async ._write(chunk, cb), and it'll handle all |
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// the drain event emission and buffering. |
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module.exports = Writable; |
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/*<replacement>*/ |
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var Buffer = require('buffer').Buffer; |
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/*</replacement>*/ |
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Writable.WritableState = WritableState; |
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/*<replacement>*/ |
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var util = require('core-util-is'); |
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util.inherits = require('inherits'); |
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/*</replacement>*/ |
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var Stream = require('stream'); |
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util.inherits(Writable, Stream); |
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function WriteReq(chunk, encoding, cb) { |
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this.chunk = chunk; |
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this.encoding = encoding; |
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this.callback = cb; |
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} |
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function WritableState(options, stream) { |
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var Duplex = require('./_stream_duplex'); |
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options = options || {}; |
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// the point at which write() starts returning false |
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// Note: 0 is a valid value, means that we always return false if |
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// the entire buffer is not flushed immediately on write() |
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var hwm = options.highWaterMark; |
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var defaultHwm = options.objectMode ? 16 : 16 * 1024; |
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this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm; |
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// object stream flag to indicate whether or not this stream |
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// contains buffers or objects. |
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this.objectMode = !!options.objectMode; |
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if (stream instanceof Duplex) |
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this.objectMode = this.objectMode || !!options.writableObjectMode; |
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// cast to ints. |
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this.highWaterMark = ~~this.highWaterMark; |
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this.needDrain = false; |
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// at the start of calling end() |
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this.ending = false; |
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// when end() has been called, and returned |
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this.ended = false; |
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// when 'finish' is emitted |
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this.finished = false; |
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// should we decode strings into buffers before passing to _write? |
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// this is here so that some node-core streams can optimize string |
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// handling at a lower level. |
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var noDecode = options.decodeStrings === false; |
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this.decodeStrings = !noDecode; |
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// Crypto is kind of old and crusty. Historically, its default string |
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// encoding is 'binary' so we have to make this configurable. |
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// Everything else in the universe uses 'utf8', though. |
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this.defaultEncoding = options.defaultEncoding || 'utf8'; |
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// not an actual buffer we keep track of, but a measurement |
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// of how much we're waiting to get pushed to some underlying |
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// socket or file. |
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this.length = 0; |
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// a flag to see when we're in the middle of a write. |
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this.writing = false; |
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// when true all writes will be buffered until .uncork() call |
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this.corked = 0; |
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// a flag to be able to tell if the onwrite cb is called immediately, |
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// or on a later tick. We set this to true at first, because any |
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// actions that shouldn't happen until "later" should generally also |
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// not happen before the first write call. |
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this.sync = true; |
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// a flag to know if we're processing previously buffered items, which |
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// may call the _write() callback in the same tick, so that we don't |
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// end up in an overlapped onwrite situation. |
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this.bufferProcessing = false; |
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// the callback that's passed to _write(chunk,cb) |
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this.onwrite = function(er) { |
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onwrite(stream, er); |
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}; |
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// the callback that the user supplies to write(chunk,encoding,cb) |
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this.writecb = null; |
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// the amount that is being written when _write is called. |
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this.writelen = 0; |
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this.buffer = []; |
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// number of pending user-supplied write callbacks |
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// this must be 0 before 'finish' can be emitted |
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this.pendingcb = 0; |
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// emit prefinish if the only thing we're waiting for is _write cbs |
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// This is relevant for synchronous Transform streams |
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this.prefinished = false; |
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// True if the error was already emitted and should not be thrown again |
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this.errorEmitted = false; |
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} |
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function Writable(options) { |
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var Duplex = require('./_stream_duplex'); |
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// Writable ctor is applied to Duplexes, though they're not |
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// instanceof Writable, they're instanceof Readable. |
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if (!(this instanceof Writable) && !(this instanceof Duplex)) |
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return new Writable(options); |
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this._writableState = new WritableState(options, this); |
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// legacy. |
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this.writable = true; |
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Stream.call(this); |
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} |
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// Otherwise people can pipe Writable streams, which is just wrong. |
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Writable.prototype.pipe = function() { |
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this.emit('error', new Error('Cannot pipe. Not readable.')); |
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}; |
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function writeAfterEnd(stream, state, cb) { |
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var er = new Error('write after end'); |
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// TODO: defer error events consistently everywhere, not just the cb |
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stream.emit('error', er); |
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process.nextTick(function() { |
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cb(er); |
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}); |
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} |
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// If we get something that is not a buffer, string, null, or undefined, |
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// and we're not in objectMode, then that's an error. |
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// Otherwise stream chunks are all considered to be of length=1, and the |
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// watermarks determine how many objects to keep in the buffer, rather than |
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// how many bytes or characters. |
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function validChunk(stream, state, chunk, cb) { |
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var valid = true; |
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if (!util.isBuffer(chunk) && |
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!util.isString(chunk) && |
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!util.isNullOrUndefined(chunk) && |
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!state.objectMode) { |
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var er = new TypeError('Invalid non-string/buffer chunk'); |
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stream.emit('error', er); |
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process.nextTick(function() { |
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cb(er); |
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}); |
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valid = false; |
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} |
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return valid; |
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} |
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Writable.prototype.write = function(chunk, encoding, cb) { |
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var state = this._writableState; |
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var ret = false; |
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if (util.isFunction(encoding)) { |
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cb = encoding; |
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encoding = null; |
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} |
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if (util.isBuffer(chunk)) |
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encoding = 'buffer'; |
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else if (!encoding) |
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encoding = state.defaultEncoding; |
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if (!util.isFunction(cb)) |
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cb = function() {}; |
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if (state.ended) |
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writeAfterEnd(this, state, cb); |
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else if (validChunk(this, state, chunk, cb)) { |
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state.pendingcb++; |
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ret = writeOrBuffer(this, state, chunk, encoding, cb); |
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} |
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return ret; |
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}; |
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Writable.prototype.cork = function() { |
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var state = this._writableState; |
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state.corked++; |
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}; |
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Writable.prototype.uncork = function() { |
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var state = this._writableState; |
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if (state.corked) { |
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state.corked--; |
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if (!state.writing && |
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!state.corked && |
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!state.finished && |
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!state.bufferProcessing && |
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state.buffer.length) |
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clearBuffer(this, state); |
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} |
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}; |
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function decodeChunk(state, chunk, encoding) { |
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if (!state.objectMode && |
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state.decodeStrings !== false && |
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util.isString(chunk)) { |
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chunk = new Buffer(chunk, encoding); |
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} |
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return chunk; |
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} |
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// if we're already writing something, then just put this |
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// in the queue, and wait our turn. Otherwise, call _write |
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// If we return false, then we need a drain event, so set that flag. |
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function writeOrBuffer(stream, state, chunk, encoding, cb) { |
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chunk = decodeChunk(state, chunk, encoding); |
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if (util.isBuffer(chunk)) |
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encoding = 'buffer'; |
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var len = state.objectMode ? 1 : chunk.length; |
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state.length += len; |
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var ret = state.length < state.highWaterMark; |
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// we must ensure that previous needDrain will not be reset to false. |
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if (!ret) |
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state.needDrain = true; |
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if (state.writing || state.corked) |
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state.buffer.push(new WriteReq(chunk, encoding, cb)); |
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else |
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doWrite(stream, state, false, len, chunk, encoding, cb); |
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return ret; |
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} |
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function doWrite(stream, state, writev, len, chunk, encoding, cb) { |
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state.writelen = len; |
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state.writecb = cb; |
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state.writing = true; |
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state.sync = true; |
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if (writev) |
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stream._writev(chunk, state.onwrite); |
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else |
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stream._write(chunk, encoding, state.onwrite); |
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state.sync = false; |
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} |
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function onwriteError(stream, state, sync, er, cb) { |
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if (sync) |
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process.nextTick(function() { |
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state.pendingcb--; |
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cb(er); |
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}); |
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else { |
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state.pendingcb--; |
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cb(er); |
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} |
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stream._writableState.errorEmitted = true; |
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stream.emit('error', er); |
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} |
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function onwriteStateUpdate(state) { |
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state.writing = false; |
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state.writecb = null; |
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state.length -= state.writelen; |
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state.writelen = 0; |
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} |
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function onwrite(stream, er) { |
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var state = stream._writableState; |
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var sync = state.sync; |
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var cb = state.writecb; |
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onwriteStateUpdate(state); |
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if (er) |
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onwriteError(stream, state, sync, er, cb); |
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else { |
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// Check if we're actually ready to finish, but don't emit yet |
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var finished = needFinish(stream, state); |
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if (!finished && |
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!state.corked && |
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!state.bufferProcessing && |
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state.buffer.length) { |
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clearBuffer(stream, state); |
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} |
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if (sync) { |
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process.nextTick(function() { |
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afterWrite(stream, state, finished, cb); |
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}); |
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} else { |
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afterWrite(stream, state, finished, cb); |
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} |
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} |
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} |
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function afterWrite(stream, state, finished, cb) { |
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if (!finished) |
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onwriteDrain(stream, state); |
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state.pendingcb--; |
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cb(); |
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finishMaybe(stream, state); |
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} |
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// Must force callback to be called on nextTick, so that we don't |
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// emit 'drain' before the write() consumer gets the 'false' return |
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// value, and has a chance to attach a 'drain' listener. |
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function onwriteDrain(stream, state) { |
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if (state.length === 0 && state.needDrain) { |
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state.needDrain = false; |
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stream.emit('drain'); |
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} |
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} |
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// if there's something in the buffer waiting, then process it |
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function clearBuffer(stream, state) { |
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state.bufferProcessing = true; |
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if (stream._writev && state.buffer.length > 1) { |
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// Fast case, write everything using _writev() |
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var cbs = []; |
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for (var c = 0; c < state.buffer.length; c++) |
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cbs.push(state.buffer[c].callback); |
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// count the one we are adding, as well. |
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// TODO(isaacs) clean this up |
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state.pendingcb++; |
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doWrite(stream, state, true, state.length, state.buffer, '', function(err) { |
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for (var i = 0; i < cbs.length; i++) { |
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state.pendingcb--; |
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cbs[i](err); |
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} |
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}); |
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// Clear buffer |
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state.buffer = []; |
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} else { |
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// Slow case, write chunks one-by-one |
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for (var c = 0; c < state.buffer.length; c++) { |
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var entry = state.buffer[c]; |
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var chunk = entry.chunk; |
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var encoding = entry.encoding; |
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var cb = entry.callback; |
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var len = state.objectMode ? 1 : chunk.length; |
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doWrite(stream, state, false, len, chunk, encoding, cb); |
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// if we didn't call the onwrite immediately, then |
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// it means that we need to wait until it does. |
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// also, that means that the chunk and cb are currently |
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// being processed, so move the buffer counter past them. |
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if (state.writing) { |
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c++; |
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break; |
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} |
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} |
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if (c < state.buffer.length) |
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state.buffer = state.buffer.slice(c); |
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else |
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state.buffer.length = 0; |
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} |
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state.bufferProcessing = false; |
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} |
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Writable.prototype._write = function(chunk, encoding, cb) { |
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cb(new Error('not implemented')); |
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}; |
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Writable.prototype._writev = null; |
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Writable.prototype.end = function(chunk, encoding, cb) { |
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var state = this._writableState; |
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if (util.isFunction(chunk)) { |
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cb = chunk; |
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chunk = null; |
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encoding = null; |
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} else if (util.isFunction(encoding)) { |
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cb = encoding; |
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encoding = null; |
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} |
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if (!util.isNullOrUndefined(chunk)) |
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this.write(chunk, encoding); |
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// .end() fully uncorks |
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if (state.corked) { |
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state.corked = 1; |
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this.uncork(); |
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} |
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// ignore unnecessary end() calls. |
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if (!state.ending && !state.finished) |
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endWritable(this, state, cb); |
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}; |
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function needFinish(stream, state) { |
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return (state.ending && |
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state.length === 0 && |
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!state.finished && |
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!state.writing); |
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} |
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function prefinish(stream, state) { |
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if (!state.prefinished) { |
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state.prefinished = true; |
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stream.emit('prefinish'); |
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} |
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} |
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function finishMaybe(stream, state) { |
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var need = needFinish(stream, state); |
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if (need) { |
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if (state.pendingcb === 0) { |
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prefinish(stream, state); |
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state.finished = true; |
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stream.emit('finish'); |
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} else |
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prefinish(stream, state); |
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} |
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return need; |
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} |
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function endWritable(stream, state, cb) { |
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state.ending = true; |
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finishMaybe(stream, state); |
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if (cb) { |
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if (state.finished) |
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process.nextTick(cb); |
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else |
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stream.once('finish', cb); |
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} |
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state.ended = true; |
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}
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