node/lib/freelist.js

// 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.

// This is a free list to avoid creating so many of the same object.
exports.FreeList = function(name, max, constructor) {
  this.name = name;
  this.constructor = constructor;
  this.max = max;
  this.list = [];
};


exports.FreeList.prototype.alloc = function() {
  //debug("alloc " + this.name + " " + this.list.length);
  return this.list.length ? this.list.shift() :
                            this.constructor.apply(this, arguments);
};


exports.FreeList.prototype.free = function(obj) {
  //debug("free " + this.name + " " + this.list.length);
  if (this.list.length < this.max) {
    this.list.push(obj);
    return true;
  }
  return false;
};