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// A bit simpler than readable streams.
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// Implement an async ._write(chunk, encoding, cb), and it'll handle all
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// the drain event emission and buffering.
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'use strict';
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module.exports = Writable;
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Writable.WritableState = WritableState;
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const util = require('util');
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const internalUtil = require('internal/util');
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const Stream = require('stream');
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const Buffer = require('buffer').Buffer;
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util.inherits(Writable, Stream);
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function nop() {}
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function WritableState(options, stream) {
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options = options || {};
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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 Stream.Duplex)
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this.objectMode = this.objectMode || !!options.writableObjectMode;
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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 = this.objectMode ? 16 : 16 * 1024;
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this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;
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// cast to ints.
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this.highWaterMark = ~~this.highWaterMark;
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// drain event flag.
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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 = onwrite.bind(undefined, stream);
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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.bufferedRequest = null;
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this.lastBufferedRequest = null;
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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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// count buffered requests
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this.bufferedRequestCount = 0;
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// allocate the first CorkedRequest, there is always
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|
// one allocated and free to use, and we maintain at most two
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|
var corkReq = { next: null, entry: null, finish: undefined };
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|
corkReq.finish = onCorkedFinish.bind(undefined, corkReq, this);
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|
this.corkedRequestsFree = corkReq;
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}
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|
WritableState.prototype.getBuffer = function getBuffer() {
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|
var current = this.bufferedRequest;
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|
var out = [];
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|
while (current) {
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out.push(current);
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current = current.next;
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}
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return out;
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};
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Object.defineProperty(WritableState.prototype, 'buffer', {
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get: internalUtil.deprecate(function() {
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|
return this.getBuffer();
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|
}, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' +
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|
'instead.', 'DEP0003')
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|
});
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|
// Test _writableState for inheritance to account for Duplex streams,
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|
// whose prototype chain only points to Readable.
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|
var realHasInstance;
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|
if (typeof Symbol === 'function' && Symbol.hasInstance) {
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|
realHasInstance = Function.prototype[Symbol.hasInstance];
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Object.defineProperty(Writable, Symbol.hasInstance, {
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value: function(object) {
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|
if (realHasInstance.call(this, object))
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return true;
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|
return object && object._writableState instanceof WritableState;
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}
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});
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} else {
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|
realHasInstance = function(object) {
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|
return object instanceof this;
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|
};
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|
}
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|
function Writable(options) {
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|
// Writable ctor is applied to Duplexes, too.
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|
// `realHasInstance` is necessary because using plain `instanceof`
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|
// would return false, as no `_writableState` property is attached.
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|
// Trying to use the custom `instanceof` for Writable here will also break the
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|
|
// Node.js LazyTransform implementation, which has a non-trivial getter for
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|
|
// `_writableState` that would lead to infinite recursion.
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|
if (!(realHasInstance.call(Writable, this)) &&
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|
!(this instanceof Stream.Duplex)) {
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|
return new Writable(options);
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|
}
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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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if (options) {
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|
if (typeof options.write === 'function')
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this._write = options.write;
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|
if (typeof options.writev === 'function')
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|
this._writev = options.writev;
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}
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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, 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(cb, er);
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|
}
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|
// Checks that a user-supplied chunk is valid, especially for the particular
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|
// mode the stream is in. Currently this means that `null` is never accepted
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|
// and undefined/non-string values are only allowed in object mode.
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|
function validChunk(stream, state, chunk, cb) {
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|
var valid = true;
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|
var er = false;
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if (chunk === null) {
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|
er = new TypeError('May not write null values to stream');
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|
} else if (typeof chunk !== 'string' &&
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|
chunk !== undefined &&
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|
!state.objectMode) {
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|
er = new TypeError('Invalid non-string/buffer chunk');
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|
}
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|
if (er) {
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|
stream.emit('error', er);
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|
process.nextTick(cb, er);
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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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|
var isBuf = (chunk instanceof Buffer);
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if (typeof encoding === 'function') {
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cb = encoding;
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|
encoding = null;
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|
}
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|
if (isBuf)
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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 (typeof cb !== 'function')
|
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|
cb = nop;
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|
if (state.ended)
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|
writeAfterEnd(this, cb);
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|
else if (isBuf || validChunk(this, state, chunk, cb)) {
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|
|
state.pendingcb++;
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|
ret = writeOrBuffer(this, state, isBuf, 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.bufferedRequest)
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|
|
clearBuffer(this, state);
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|
|
}
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|
|
};
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|
|
Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
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|
|
// node::ParseEncoding() requires lower case.
|
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|
|
if (typeof encoding === 'string')
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|
|
encoding = encoding.toLowerCase();
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|
|
if (!Buffer.isEncoding(encoding))
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|
|
throw new TypeError('Unknown encoding: ' + encoding);
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|
|
this._writableState.defaultEncoding = encoding;
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|
|
return this;
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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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|
|
typeof chunk === 'string') {
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|
|
chunk = Buffer.from(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, isBuf, chunk, encoding, cb) {
|
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|
|
if (!isBuf) {
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|
|
var newChunk = decodeChunk(state, chunk, encoding);
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|
|
if (chunk !== newChunk) {
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|
|
encoding = 'buffer';
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|
|
chunk = newChunk;
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|
}
|
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|
|
}
|
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|
|
var len = state.objectMode ? 1 : chunk.length;
|
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|
|
|
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|
|
state.length += len;
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|
|
|
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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.
|
|
|
|
if (!ret)
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|
|
state.needDrain = true;
|
|
|
|
|
|
|
|
if (state.writing || state.corked) {
|
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|
|
var last = state.lastBufferedRequest;
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|
|
state.lastBufferedRequest = { chunk, encoding, callback: cb, next: null };
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|
|
if (last) {
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|
|
last.next = state.lastBufferedRequest;
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|
|
} else {
|
|
|
|
state.bufferedRequest = state.lastBufferedRequest;
|
|
|
|
}
|
|
|
|
state.bufferedRequestCount += 1;
|
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|
|
} else {
|
|
|
|
doWrite(stream, state, false, len, chunk, encoding, cb);
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|
|
}
|
|
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|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
function doWrite(stream, state, writev, len, chunk, encoding, cb) {
|
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|
|
state.writelen = len;
|
|
|
|
state.writecb = cb;
|
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|
|
state.writing = true;
|
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|
|
state.sync = true;
|
|
|
|
if (writev)
|
|
|
|
stream._writev(chunk, state.onwrite);
|
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|
|
else
|
|
|
|
stream._write(chunk, encoding, state.onwrite);
|
|
|
|
state.sync = false;
|
|
|
|
}
|
|
|
|
|
|
|
|
function onwriteError(stream, state, sync, er, cb) {
|
|
|
|
--state.pendingcb;
|
|
|
|
if (sync)
|
|
|
|
process.nextTick(cb, er);
|
|
|
|
else
|
|
|
|
cb(er);
|
|
|
|
|
|
|
|
stream._writableState.errorEmitted = true;
|
|
|
|
stream.emit('error', er);
|
|
|
|
}
|
|
|
|
|
|
|
|
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) {
|
|
|
|
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;
|
|
|
|
while (entry) {
|
|
|
|
buffer[count] = entry;
|
|
|
|
entry = entry.next;
|
|
|
|
count += 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
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 {
|
|
|
|
var corkReq = { next: null, entry: null, finish: undefined };
|
|
|
|
corkReq.finish = onCorkedFinish.bind(undefined, corkReq, state);
|
|
|
|
state.corkedRequestsFree = corkReq;
|
|
|
|
}
|
|
|
|
} 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;
|
|
|
|
// 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.bufferedRequestCount = 0;
|
|
|
|
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 prefinish(stream, state) {
|
|
|
|
if (!state.prefinished) {
|
|
|
|
state.prefinished = true;
|
|
|
|
stream.emit('prefinish');
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
function finishMaybe(stream, state) {
|
|
|
|
var need = needFinish(state);
|
|
|
|
if (need) {
|
|
|
|
if (state.pendingcb === 0) {
|
|
|
|
prefinish(stream, state);
|
|
|
|
state.finished = true;
|
|
|
|
stream.emit('finish');
|
|
|
|
} else {
|
|
|
|
prefinish(stream, state);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
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;
|
|
|
|
}
|
|
|
|
if (state.corkedRequestsFree) {
|
|
|
|
state.corkedRequestsFree.next = corkReq;
|
|
|
|
} else {
|
|
|
|
state.corkedRequestsFree = corkReq;
|
|
|
|
}
|
|
|
|
}
|