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CrowdControl/Assets/Plugins/UniTask/Runtime/Internal/ArrayPool.cs

151 lines
4.0 KiB
C#

#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
using System;
using System.Threading;
namespace Cysharp.Threading.Tasks.Internal
{
// Same interface as System.Buffers.ArrayPool<T> but only provides Shared.
internal sealed class ArrayPool<T>
{
// Same size as System.Buffers.DefaultArrayPool<T>
const int DefaultMaxNumberOfArraysPerBucket = 50;
static readonly T[] EmptyArray = new T[0];
public static readonly ArrayPool<T> Shared = new ArrayPool<T>();
readonly MinimumQueue<T[]>[] buckets;
readonly SpinLock[] locks;
ArrayPool()
{
// see: GetQueueIndex
buckets = new MinimumQueue<T[]>[18];
locks = new SpinLock[18];
for (int i = 0; i < buckets.Length; i++)
{
buckets[i] = new MinimumQueue<T[]>(4);
locks[i] = new SpinLock(false);
}
}
public T[] Rent(int minimumLength)
{
if (minimumLength < 0)
{
throw new ArgumentOutOfRangeException("minimumLength");
}
else if (minimumLength == 0)
{
return EmptyArray;
}
var size = CalculateSize(minimumLength);
var index = GetQueueIndex(size);
if (index != -1)
{
var q = buckets[index];
var lockTaken = false;
try
{
locks[index].Enter(ref lockTaken);
if (q.Count != 0)
{
return q.Dequeue();
}
}
finally
{
if (lockTaken) locks[index].Exit(false);
}
}
return new T[size];
}
public void Return(T[] array, bool clearArray = false)
{
if (array == null || array.Length == 0)
{
return;
}
var index = GetQueueIndex(array.Length);
if (index != -1)
{
if (clearArray)
{
Array.Clear(array, 0, array.Length);
}
var q = buckets[index];
var lockTaken = false;
try
{
locks[index].Enter(ref lockTaken);
if (q.Count > DefaultMaxNumberOfArraysPerBucket)
{
return;
}
q.Enqueue(array);
}
finally
{
if (lockTaken) locks[index].Exit(false);
}
}
}
static int CalculateSize(int size)
{
size--;
size |= size >> 1;
size |= size >> 2;
size |= size >> 4;
size |= size >> 8;
size |= size >> 16;
size += 1;
if (size < 8)
{
size = 8;
}
return size;
}
static int GetQueueIndex(int size)
{
switch (size)
{
case 8: return 0;
case 16: return 1;
case 32: return 2;
case 64: return 3;
case 128: return 4;
case 256: return 5;
case 512: return 6;
case 1024: return 7;
case 2048: return 8;
case 4096: return 9;
case 8192: return 10;
case 16384: return 11;
case 32768: return 12;
case 65536: return 13;
case 131072: return 14;
case 262144: return 15;
case 524288: return 16;
case 1048576: return 17; // max array length
default:
return -1;
}
}
}
}