foo.cs

//
// CollectionCache.cs
//
// Author:
//       Mike Krüger <mikkrg@microsoft.com>
//
// Copyright (c) 2019 Microsoft Corporation. All rights reserved.
//
// 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.

using System;
using System.Collections.Generic;
using Microsoft.Extensions.ObjectPool;

namespace MonoDevelop.Core
{
	public static class CollectionCache
	{
		public static List<T> AllocateList<T> () => Pool<T, List<T>>.Allocate ();

		public static void Free<T> (List<T> obj) => Pool<T, List<T>>.Deallocate (obj);

		public static HashSet<T> AllocateHashSet<T> () => Pool<T, HashSet<T>>.Allocate ();

		public static void Free<T> (HashSet<T> obj) => Pool<T, HashSet<T>>.Deallocate (obj);

		public static Dictionary<T, U> AllocateDictionary<T, U> () => Pool<KeyValuePair<T, U>, Dictionary<T, U>>.Allocate ();

		public static void Free<T, U> (Dictionary<T, U> obj) => Pool<KeyValuePair<T, U>, Dictionary<T, U>>.Deallocate (obj);

		static class Pool<T, U> where U : class, ICollection<T>, new()
		{
			static readonly ObjectPool<U> pool = new DefaultObjectPoolProvider ().Create (new PooledObjectPolicy ());

			internal static U Allocate () => pool.Get ();

			internal static void Deallocate (U collection)
			{
				if (collection == null)
					throw new ArgumentNullException (nameof (collection));
				pool.Return (collection);
			}

			class PooledObjectPolicy : PooledObjectPolicy<U>
			{
				public override U Create () => new U ();

				public override bool Return (U obj)
				{
					obj.Clear ();

					return true;
				}

			}
		}

		public static Stack<T> AllocateStack<T> () => StackPool<T>.Allocate ();

		public static void Free<T> (Stack<T> obj) => StackPool<T>.Deallocate (obj);

		static class StackPool<T>
		{
			static readonly ObjectPool<Stack<T>> pool = new DefaultObjectPoolProvider ().Create (new PooledObjectPolicy ());

			internal static Stack<T> Allocate () => pool.Get ();

			internal static void Deallocate (Stack<T> stack)
			{
				if (stack == null)
					throw new ArgumentNullException (nameof (stack));
				pool.Return (stack);
			}

			class PooledObjectPolicy : PooledObjectPolicy<Stack<T>>
			{
				public override Stack<T> Create () => new Stack<T> ();

				public override bool Return (Stack<T> obj)
				{
					obj.Clear ();

					return true;
				}

			}
		}

		public static Queue<T> AllocateQueue<T> () => QueuePool<T>.Allocate ();

		public static void Free<T> (Queue<T> obj) => QueuePool<T>.Deallocate (obj);

		static class QueuePool<T>
		{
			static readonly ObjectPool<Queue<T>> pool = new DefaultObjectPoolProvider ().Create (new PooledObjectPolicy ());

			internal static Queue<T> Allocate () => pool.Get ();

			internal static void Deallocate (Queue<T> queue)
			{
				if (queue == null)
					throw new ArgumentNullException (nameof (queue));
				pool.Return (queue);
			}

			class PooledObjectPolicy : PooledObjectPolicy<Queue<T>>
			{
				public override Queue<T> Create () => new Queue<T> ();

				public override bool Return (Queue<T> obj)
				{
					obj.Clear ();

					return true;
				}

			}
		}
	}
}