ObjectPool`1.cs

instructions.md

Usage

Instantiation

var objectPool = new ObjectPool<MyObject>(poolSize: 10);

Renting

MyObject obj = objectPool.Rent();

Recycling

objectPool.Return(obj);

ObjectPool`1.cs

    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Threading;

    namespace GameServ
    {
        public class ObjectPool<TObject>
        {
            private int maxPoolSize;
            private Stack<TObject> poolCache;
            private Func<TObject> factory;

            public ObjectPool(int poolSize)
            {
                this.maxPoolSize = poolSize;
                this.poolCache = new Stack<TObject>();
            }

            public ObjectPool(int poolSize, Func<TObject> factory) : this(poolSize)
            {
                this.factory = factory;
            }

            public TObject Rent()
            {
                TObject instance = default(TObject);
                Monitor.Enter(this.poolCache);
                if (this.poolCache.Count > 0)
                {
                    instance = this.poolCache.Pop();
                }

                Monitor.Exit(this.poolCache);

                if (instance != null)
                {
                    return instance;
                }

                // New instances don't need to be prepared for re-use, so we just return it.
                if (this.factory == null)
                {
                    return (TObject)Activator.CreateInstance(typeof(TObject));
                }
                else
                {
                    return this.factory();
                }
            }

            public void Return(TObject instanceObject)
            {
                Monitor.Enter(poolCache);
                if (this.poolCache.Count >= this.maxPoolSize)
                {
                    return;
                }

                // TODO: Convert Stack into an array.
                // We'll track the current index by decrementing the index in Rent, and incrementing in Return
                // Upon Renting, we'll set pool[index] to null, then reduce index by 1. This lets us manage an
                // array and have zero lookup costs.
                this.poolCache.Push(instanceObject);
                Monitor.Exit(poolCache);
            }
        }
    }