115 lines
2.7 KiB
JavaScript
115 lines
2.7 KiB
JavaScript
'use strict';
|
|
|
|
var stream = require('stream');
|
|
var constants = require('./constants');
|
|
var util = require('util');
|
|
|
|
var ReadableStreamBuffer = module.exports = function(opts) {
|
|
var that = this;
|
|
opts = opts || {};
|
|
|
|
stream.Readable.call(this, opts);
|
|
|
|
this.stopped = false;
|
|
|
|
var frequency = opts.hasOwnProperty('frequency') ? opts.frequency : constants.DEFAULT_FREQUENCY;
|
|
var chunkSize = opts.chunkSize || constants.DEFAULT_CHUNK_SIZE;
|
|
var initialSize = opts.initialSize || constants.DEFAULT_INITIAL_SIZE;
|
|
var incrementAmount = opts.incrementAmount || constants.DEFAULT_INCREMENT_AMOUNT;
|
|
|
|
var size = 0;
|
|
var buffer = new Buffer(initialSize);
|
|
var allowPush = false;
|
|
|
|
var sendData = function() {
|
|
var amount = Math.min(chunkSize, size);
|
|
var sendMore = false;
|
|
|
|
if (amount > 0) {
|
|
var chunk = null;
|
|
chunk = new Buffer(amount);
|
|
buffer.copy(chunk, 0, 0, amount);
|
|
|
|
sendMore = that.push(chunk) !== false;
|
|
allowPush = sendMore;
|
|
|
|
buffer.copy(buffer, 0, amount, size);
|
|
size -= amount;
|
|
}
|
|
|
|
if(size === 0 && that.stopped) {
|
|
that.push(null);
|
|
}
|
|
|
|
if (sendMore) {
|
|
sendData.timeout = setTimeout(sendData, frequency);
|
|
}
|
|
else {
|
|
sendData.timeout = null;
|
|
}
|
|
};
|
|
|
|
this.stop = function() {
|
|
if (this.stopped) {
|
|
throw new Error('stop() called on already stopped ReadableStreamBuffer');
|
|
}
|
|
this.stopped = true;
|
|
|
|
if (size === 0) {
|
|
this.push(null);
|
|
}
|
|
};
|
|
|
|
this.size = function() {
|
|
return size;
|
|
};
|
|
|
|
this.maxSize = function() {
|
|
return buffer.length;
|
|
};
|
|
|
|
var increaseBufferIfNecessary = function(incomingDataSize) {
|
|
if((buffer.length - size) < incomingDataSize) {
|
|
var factor = Math.ceil((incomingDataSize - (buffer.length - size)) / incrementAmount);
|
|
|
|
var newBuffer = new Buffer(buffer.length + (incrementAmount * factor));
|
|
buffer.copy(newBuffer, 0, 0, size);
|
|
buffer = newBuffer;
|
|
}
|
|
};
|
|
|
|
var kickSendDataTask = function () {
|
|
if (!sendData.timeout && allowPush) {
|
|
sendData.timeout = setTimeout(sendData, frequency);
|
|
}
|
|
}
|
|
|
|
this.put = function(data, encoding) {
|
|
if (that.stopped) {
|
|
throw new Error('Tried to write data to a stopped ReadableStreamBuffer');
|
|
}
|
|
|
|
if(Buffer.isBuffer(data)) {
|
|
increaseBufferIfNecessary(data.length);
|
|
data.copy(buffer, size, 0);
|
|
size += data.length;
|
|
}
|
|
else {
|
|
data = data + '';
|
|
var dataSizeInBytes = Buffer.byteLength(data);
|
|
increaseBufferIfNecessary(dataSizeInBytes);
|
|
buffer.write(data, size, encoding || 'utf8');
|
|
size += dataSizeInBytes;
|
|
}
|
|
|
|
kickSendDataTask();
|
|
};
|
|
|
|
this._read = function() {
|
|
allowPush = true;
|
|
kickSendDataTask();
|
|
};
|
|
};
|
|
|
|
util.inherits(ReadableStreamBuffer, stream.Readable);
|