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/*!
* 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;
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