hObjectPool.cs

#region Copyright Notice & License Information
//
// hObjectPool.cs
//
// Author:
//       Matthew Davey <matthew.davey@dotbunny.com>
//
// Copyright (c) 2013 dotBunny Inc. (http://www.dotbunny.com)
//
// 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.
#endregion

using UnityEngine;

/// <summary>
/// A drop in implementation of the Hydrogen.Core.ObjectPool. This simply makes the class an accessible singleton 
/// with some very simple additional functionality.
/// </summary>
[AddComponentMenu ("Hydrogen/Singletons/Object Pool")]
public sealed class hObjectPool : Hydrogen.Core.ObjectPool
{
        /// <summary>
        /// Should this object pool survive scene switches?
        /// </summary>
        public bool Persistent = true;
        /// <summary>
        /// Internal fail safe to maintain instance across threads.
        /// </summary>
        /// <remarks>
        /// Multithreaded Safe Singleton Pattern.
        /// </remarks>
        /// <description>
        /// http://msdn.microsoft.com/en-us/library/ms998558.aspx
        /// </description>
        static readonly System.Object _syncRoot = new System.Object ();
        /// <summary>
        /// Internal reference to the static instance of the object pool.
        /// </summary>
        static volatile hObjectPool _staticInstance;

        /// <summary>
        /// Gets the object pool instance, creating one if none is found.
        /// </summary>
        /// <value>
        /// The Object Pool.
        /// </value>
        public static hObjectPool Instance {
                get {
                        if (_staticInstance == null) {
                                lock (_syncRoot) {
                                        _staticInstance = FindObjectOfType (typeof(hObjectPool)) as hObjectPool;

                                        // If we don't have it, lets make it!
                                        if (_staticInstance == null) {
                                                var go = GameObject.Find (Hydrogen.Components.DefaultSingletonName) ??
                                                         new GameObject (Hydrogen.Components.DefaultSingletonName);

                                                go.AddComponent<hObjectPool> ();
                                                _staticInstance = go.GetComponent<hObjectPool> ();  
                                        }
                                }
                        }
                        return _staticInstance;
                }
        }

        /// <summary>
        /// Does an Object Pool already exist?
        /// </summary>
        public static bool Exists ()
        {
                return _staticInstance != null;
        }

        /// <summary>
        /// Unity's Awake Event
        /// </summary>
        protected override void Awake ()
        {   
                // Make sure to do the object pools normal initialization
                base.Awake ();

                // Should this gameObject be kept around :) I think so.
                if (Persistent)
                        DontDestroyOnLoad (gameObject);

        }
}