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JavaScript

// 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);
};