387 lines
11 KiB
JavaScript
387 lines
11 KiB
JavaScript
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// 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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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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this.highWaterMark = (hwm || hwm === 0) ? hwm : 16 * 1024;
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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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// 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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// 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, becuase 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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// 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 (!Buffer.isBuffer(chunk) &&
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'string' !== typeof chunk &&
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chunk !== null &&
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chunk !== undefined &&
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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 (typeof encoding === 'function') {
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cb = encoding;
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encoding = null;
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}
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if (Buffer.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 (typeof cb !== 'function')
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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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ret = writeOrBuffer(this, state, chunk, encoding, cb);
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return ret;
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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 = 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 (Buffer.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)
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state.buffer.push(new WriteReq(chunk, encoding, cb));
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else
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doWrite(stream, state, len, chunk, encoding, cb);
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return ret;
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}
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function doWrite(stream, state, 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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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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cb(er);
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});
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else
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cb(er);
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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 && !state.bufferProcessing && state.buffer.length)
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clearBuffer(stream, state);
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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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cb();
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if (finished)
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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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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, 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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state.bufferProcessing = false;
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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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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.end = function(chunk, encoding, cb) {
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var state = this._writableState;
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if (typeof chunk === 'function') {
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cb = chunk;
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chunk = null;
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encoding = null;
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} else 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 (typeof chunk !== 'undefined' && chunk !== null)
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this.write(chunk, encoding);
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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 finishMaybe(stream, state) {
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var need = needFinish(stream, state);
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if (need) {
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state.finished = true;
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stream.emit('finish');
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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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