| // 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, cb), and it'll handle all |
| // the drain event emission and buffering. |
| |
| module.exports = Writable; |
| Writable.WritableState = WritableState; |
| |
| var util = require('util'); |
| var assert = require('assert'); |
| var Stream = require('stream'); |
| |
| util.inherits(Writable, Stream); |
| |
| function WriteReq(chunk, encoding, cb) { |
| this.chunk = chunk; |
| this.encoding = encoding; |
| this.callback = cb; |
| } |
| |
| function WritableState(options, stream) { |
| options = options || {}; |
| |
| // 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; |
| this.highWaterMark = (hwm || hwm === 0) ? hwm : 16 * 1024; |
| |
| // object stream flag to indicate whether or not this stream |
| // contains buffers or objects. |
| this.objectMode = !!options.objectMode; |
| |
| // 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; |
| |
| // 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, becuase 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.buffer = []; |
| } |
| |
| function Writable(options) { |
| // Writable ctor is applied to Duplexes, though they're not |
| // instanceof Writable, they're instanceof Readable. |
| if (!(this instanceof Writable) && !(this instanceof Stream.Duplex)) |
| return new Writable(options); |
| |
| this._writableState = new WritableState(options, this); |
| |
| // legacy. |
| this.writable = true; |
| |
| 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, state, cb) { |
| var er = new Error('write after end'); |
| // TODO: defer error events consistently everywhere, not just the cb |
| stream.emit('error', er); |
| process.nextTick(function() { |
| 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; |
| if (!Buffer.isBuffer(chunk) && |
| 'string' !== typeof chunk && |
| chunk !== null && |
| chunk !== undefined && |
| !state.objectMode) { |
| var er = new TypeError('Invalid non-string/buffer chunk'); |
| stream.emit('error', er); |
| process.nextTick(function() { |
| 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 = function() {}; |
| |
| if (state.ended) |
| writeAfterEnd(this, state, cb); |
| else if (validChunk(this, state, chunk, cb)) |
| ret = writeOrBuffer(this, state, chunk, encoding, cb); |
| |
| return ret; |
| }; |
| |
| function decodeChunk(state, chunk, encoding) { |
| if (!state.objectMode && |
| state.decodeStrings !== false && |
| typeof chunk === 'string') { |
| chunk = new Buffer(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; |
| state.needDrain = !ret; |
| |
| if (state.writing) |
| state.buffer.push(new WriteReq(chunk, encoding, cb)); |
| else |
| doWrite(stream, state, len, chunk, encoding, cb); |
| |
| return ret; |
| } |
| |
| function doWrite(stream, state, len, chunk, encoding, cb) { |
| state.writelen = len; |
| state.writecb = cb; |
| state.writing = true; |
| state.sync = true; |
| stream._write(chunk, encoding, state.onwrite); |
| state.sync = false; |
| } |
| |
| function onwriteError(stream, state, sync, er, cb) { |
| if (sync) |
| process.nextTick(function() { |
| cb(er); |
| }); |
| else |
| cb(er); |
| |
| 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(stream, state); |
| |
| if (!finished && !state.bufferProcessing && state.buffer.length) |
| clearBuffer(stream, state); |
| |
| if (sync) { |
| process.nextTick(function() { |
| afterWrite(stream, state, finished, cb); |
| }); |
| } else { |
| afterWrite(stream, state, finished, cb); |
| } |
| } |
| } |
| |
| function afterWrite(stream, state, finished, cb) { |
| if (!finished) |
| onwriteDrain(stream, state); |
| cb(); |
| if (finished) |
| 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; |
| |
| for (var c = 0; c < state.buffer.length; c++) { |
| var entry = state.buffer[c]; |
| var chunk = entry.chunk; |
| var encoding = entry.encoding; |
| var cb = entry.callback; |
| var len = state.objectMode ? 1 : chunk.length; |
| |
| doWrite(stream, state, len, chunk, encoding, cb); |
| |
| // 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) { |
| c++; |
| break; |
| } |
| } |
| |
| state.bufferProcessing = false; |
| if (c < state.buffer.length) |
| state.buffer = state.buffer.slice(c); |
| else |
| state.buffer.length = 0; |
| } |
| |
| Writable.prototype._write = function(chunk, encoding, cb) { |
| cb(new Error('not implemented')); |
| }; |
| |
| 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 (typeof chunk !== 'undefined' && chunk !== null) |
| this.write(chunk, encoding); |
| |
| // ignore unnecessary end() calls. |
| if (!state.ending && !state.finished) |
| endWritable(this, state, cb); |
| }; |
| |
| |
| function needFinish(stream, state) { |
| return (state.ending && |
| state.length === 0 && |
| !state.finished && |
| !state.writing); |
| } |
| |
| function finishMaybe(stream, state) { |
| var need = needFinish(stream, state); |
| if (need) { |
| state.finished = true; |
| stream.emit('finish'); |
| } |
| 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; |
| } |