60 lines
1.6 KiB
JavaScript
60 lines
1.6 KiB
JavaScript
/*!
|
|
* ws: a node.js websocket client
|
|
* Copyright(c) 2011 Einar Otto Stangvik <einaros@gmail.com>
|
|
* MIT Licensed
|
|
*/
|
|
|
|
var util = require('util');
|
|
|
|
function BufferPool(initialSize, growStrategy, shrinkStrategy) {
|
|
if (typeof initialSize === 'function') {
|
|
shrinkStrategy = growStrategy;
|
|
growStrategy = initialSize;
|
|
initialSize = 0;
|
|
}
|
|
else if (typeof initialSize === 'undefined') {
|
|
initialSize = 0;
|
|
}
|
|
this._growStrategy = (growStrategy || function(db, size) {
|
|
return db.used + size;
|
|
}).bind(null, this);
|
|
this._shrinkStrategy = (shrinkStrategy || function(db) {
|
|
return initialSize;
|
|
}).bind(null, this);
|
|
this._buffer = initialSize ? new Buffer(initialSize) : null;
|
|
this._offset = 0;
|
|
this._used = 0;
|
|
this._changeFactor = 0;
|
|
this.__defineGetter__('size', function(){
|
|
return this._buffer == null ? 0 : this._buffer.length;
|
|
});
|
|
this.__defineGetter__('used', function(){
|
|
return this._used;
|
|
});
|
|
}
|
|
|
|
BufferPool.prototype.get = function(length) {
|
|
if (this._buffer == null || this._offset + length > this._buffer.length) {
|
|
var newBuf = new Buffer(this._growStrategy(length));
|
|
this._buffer = newBuf;
|
|
this._offset = 0;
|
|
}
|
|
this._used += length;
|
|
var buf = this._buffer.slice(this._offset, this._offset + length);
|
|
this._offset += length;
|
|
return buf;
|
|
}
|
|
|
|
BufferPool.prototype.reset = function(forceNewBuffer) {
|
|
var len = this._shrinkStrategy();
|
|
if (len < this.size) this._changeFactor -= 1;
|
|
if (forceNewBuffer || this._changeFactor < -2) {
|
|
this._changeFactor = 0;
|
|
this._buffer = len ? new Buffer(len) : null;
|
|
}
|
|
this._offset = 0;
|
|
this._used = 0;
|
|
}
|
|
|
|
module.exports = BufferPool;
|