ModernUO/Projects/Server/Utilities/RefPool.cs
2020-02-20 09:45:55 -08:00

114 lines
4.5 KiB
C#

using System;
using System.Collections.Generic;
namespace Server.Utilities
{
/// <summary> A resource reference object that can be disposed. </summary>
/// <remarks>
/// Disposing the reference is expected to return itself back into the
/// original pool that created it.
/// </remarks>
public interface IRef : IDisposable { }
/// <summary>
/// Base implementation of the <see cref="IRef"/> interface.
/// </summary>
/// <remarks>
/// New implementations of <see cref="IRef"/> should either derive from, or mirror
/// the functionality of this base implementation.
/// </remarks>
/// <typeparam name="TDerived"></typeparam>
public abstract class BaseRef<TDerived> : IRef where TDerived : IRef
{
private RefPool<TDerived> m_Pool;
public BaseRef(RefPool<TDerived> pool)
{
m_Pool = pool;
}
protected abstract void OnDispose();
public void Dispose()
{
OnDispose();
m_Pool.Return((TDerived)(object)this);
}
}
/// <summary>
/// A resource reference pool that manages a collection of reusable resources.
/// </summary>
/// <typeparam name="TRef">The <see cref="IRef"/> resource type the pool will contain.</typeparam>
public class RefPool<TRef> where TRef : IRef
{
public delegate TRef Generator(RefPool<TRef> targetPool);
public const int DEFAULT_RESOURCE_RETENTION = 10;
private Stack<TRef> m_Resources = new Stack<TRef>();
private Generator m_Generator;
private int m_MaxRefrenceRetention;
/// <summary>
/// The maximum number of unused resources to hold in the pool.
/// </summary>
public int MaxRefrenceRetention
{
get => m_MaxRefrenceRetention;
set
{
m_MaxRefrenceRetention = value;
while (m_Resources.Count > value) m_Resources.Pop();
}
}
/// <param name="generator">The generator function for creating new resources.</param>
/// <param name="preGenerateCount">An amount of resources that should be pre-generated during initialization of the resource pool.</param>
public RefPool(Generator generator, int preGenerateCount = 0, int maxRefrenceRetention = DEFAULT_RESOURCE_RETENTION)
{
if (generator == null)
throw new ArgumentNullException(nameof(generator));
if (preGenerateCount > maxRefrenceRetention)
throw new IndexOutOfRangeException($"{nameof(preGenerateCount)} greater than {nameof(maxRefrenceRetention)}");
m_Generator = generator;
m_MaxRefrenceRetention = maxRefrenceRetention;
while (--preGenerateCount >= 0) m_Resources.Push(generator(this));
}
/// <summary>
/// Retrieves a resource reference that is managed by this <see cref="RefPool{TRef}"/>. If the pool is has unused resources,
/// it will remove one from the pool and return it; otherwise, a new resource will be generated.
/// </summary>
/// <returns>Unused resource, or a new resource if no unused resources available.</returns>
public TRef Get() => m_Resources.TryPop(out TRef item) ? item : m_Generator(this);
/// <summary>
/// Returns a resource reference to the pool of unused resources.
/// </summary>
/// <param name="queueRef">Resource to be returned.</param>
public void Return(TRef queueRef)
{
if (m_Resources.Count < MaxRefrenceRetention)
m_Resources.Push(queueRef);
}
}
/// <inheritdoc/>
public class QueueRef<T> : Queue<T>, IRef
{
private RefPool<QueueRef<T>> m_Pool;
private QueueRef(RefPool<QueueRef<T>> pool) { m_Pool = pool; }
/// <summary>Clears the queue and returns this resource to its parent resource pool.</summary>
public void Dispose() { Clear(); m_Pool.Return(this); }
/// <summary>
/// Generator function for creating instances of the <see cref="QueueRef{T}"/> resource.
/// </summary>
public static RefPool<QueueRef<T>>.Generator Generate = (targetPool) => new QueueRef<T>(targetPool);
}
/// <inheritdoc/>
public class StackRef<T> : Stack<T>, IRef
{
private RefPool<StackRef<T>> m_Pool;
private StackRef(RefPool<StackRef<T>> pool) { m_Pool = pool; }
/// <summary>Clears the stack and returns this resource to its parent resource pool.</summary>
public void Dispose() { Clear(); m_Pool.Return(this); }
/// <summary>
/// Generator function for creating instances of the <see cref="StackRef{T}"/> resource.
/// </summary>
public static RefPool<StackRef<T>>.Generator Generate = (targetPool) => new StackRef<T>(targetPool);
}
}