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| // 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>*/
var processNextTick = require('process-nextick-args');
/*</replacement>*/
/*<replacement>*/
var asyncWrite = !process.browser && ['v0.10', 'v0.9.'].indexOf(process.version.slice(0, 5)) > -1 ? setImmediate : processNextTick;
/*</replacement>*/
Writable.WritableState = WritableState;
/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/
/*<replacement>*/
var internalUtil = {
deprecate: require('util-deprecate')
};
/*</replacement>*/
/*<replacement>*/
var Stream;
(function () {
try {
Stream = require('st' + 'ream');
} catch (_) {} finally {
Iif (!Stream) Stream = require('events').EventEmitter;
}
})();
/*</replacement>*/
var Buffer = require('buffer').Buffer;
/*<replacement>*/
var bufferShim = require('buffer-shims');
/*</replacement>*/
util.inherits(Writable, Stream);
function nop() {}
function WriteReq(chunk, encoding, cb) {
this.chunk = chunk;
this.encoding = encoding;
this.callback = cb;
this.next = null;
}
var Duplex;
function WritableState(options, stream) {
Duplex = Duplex || require('./_stream_duplex');
options = options || {};
// object stream flag to indicate whether or not this stream
// contains buffers or objects.
this.objectMode = !!options.objectMode;
if (stream instanceof Duplex) 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 defaultHwm = this.objectMode ? 16 : 16 * 1024;
this.highWaterMark = hwm || hwm === 0 ? hwm : defaultHwm;
// cast to ints.
this.highWaterMark = ~ ~this.highWaterMark;
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;
// 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 writableStateGetBuffer() {
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.')
});
} catch (_) {}
})();
var Duplex;
function Writable(options) {
Duplex = Duplex || require('./_stream_duplex');
// Writable ctor is applied to Duplexes, though they're not
// instanceof Writable, they're instanceof Readable.
if (!(this instanceof Writable) && !(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;
}
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);
processNextTick(cb, er);
}
// If we get something that is not a buffer, string, null, or undefined,
// and we're not in objectMode, then that's an error.
// Otherwise stream chunks are all considered to be of length=1, and the
// watermarks determine how many objects to keep in the buffer, rather than
// how many bytes or characters.
function validChunk(stream, state, chunk, cb) {
var valid = true;
var er = false;
// Always throw error if a null is written
// if we are not in object mode then throw
// if it is not a buffer, string, or undefined.
if (chunk === null) {
er = new TypeError('May not write null values to stream');
} else if (!Buffer.isBuffer(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
er = new TypeError('Invalid non-string/buffer chunk');
}
if (er) {
stream.emit('error', er);
processNextTick(cb, er);
valid = false;
}
return valid;
}
Writable.prototype.write = function (chunk, encoding, cb) {
var state = this._writableState;
var ret = false;
if (typeof encoding === 'function') {
cb = encoding;
encoding = null;
}
if (Buffer.isBuffer(chunk)) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding;
if (typeof cb !== 'function') cb = nop;
if (state.ended) writeAfterEnd(this, cb);else if (validChunk(this, state, chunk, cb)) {
state.pendingcb++;
ret = writeOrBuffer(this, state, chunk, encoding, cb);
}
return ret;
};
Writable.prototype.cork = function () {
var state = this._writableState;
state.corked++;
};
Writable.prototype.uncork = function () {
var state = this._writableState;
Eif (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 = bufferShim.from(chunk, encoding);
}
return chunk;
}
// 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, chunk, encoding, cb) {
chunk = decodeChunk(state, chunk, encoding);
if (Buffer.isBuffer(chunk)) encoding = 'buffer';
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 = new WriteReq(chunk, encoding, cb);
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) processNextTick(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);
Iif (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;
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;
Iif (holder.next) {
state.corkedRequestsFree = holder.next;
holder.next = null;
} else {
state.corkedRequestsFree = new CorkedRequest(state);
}
} 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('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) processNextTick(cb);else stream.once('finish', cb);
}
state.ended = true;
stream.writable = false;
}
// 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 (err) {
var entry = _this.entry;
_this.entry = null;
while (entry) {
var cb = entry.callback;
state.pendingcb--;
cb(err);
entry = entry.next;
}
Eif (state.corkedRequestsFree) {
state.corkedRequestsFree.next = _this;
} else {
state.corkedRequestsFree = _this;
}
};
} |