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/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Data.Caching.ObjectCache
* File: BlobCacheBucket.cs
*
* BlobCacheBucket.cs is part of VNLib.Data.Caching.ObjectCache which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Data.Caching.ObjectCache is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Data.Caching.ObjectCache is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System.Threading;
using System.Threading.Tasks;
using VNLib.Utils.Memory;
namespace VNLib.Data.Caching.ObjectCache
{
/// <summary>
/// A concrete implementation of an <see cref="IBlobCacheBucket"/>
/// </summary>
public sealed class BlobCacheBucket : IBlobCacheBucket
{
private readonly IBlobCache _cacheTable;
private readonly SemaphoreSlim _lock;
///<inheritdoc/>
public uint Id { get; }
/// <summary>
/// Initialzies a new <see cref="BlobCacheBucket"/> and its underlying
/// <see cref="IBlobCache"/>
/// </summary>
/// <param name="bucketCapacity">
/// The maxium number of entries allowed in the LRU cache
/// before LRU overflow happens.
/// </param>
/// <param name="bucketId">The unique id of the new bucket</param>
/// <param name="heap">The heap to allocate object cache buffers</param>
/// <param name="persistantCache">An optional <see cref="IPersistantCacheStore"/> for cache persistance</param>
public BlobCacheBucket(uint bucketId, int bucketCapacity, IUnmangedHeap heap, IPersistantCacheStore? persistantCache)
{
Id = bucketId;
_lock = new(1, 1);
_cacheTable = new BlobCache(bucketId, bucketCapacity, heap, persistantCache);
}
///<inheritdoc/>
public void Dispose()
{
_cacheTable.Dispose();
_lock.Dispose();
}
///<inheritdoc/>
public async ValueTask<IBlobCache> ManualWaitAsync(CancellationToken cancellation)
{
//try to enter the lock synchronously
if (_lock.Wait(0, CancellationToken.None))
{
return _cacheTable;
}
else
{
await _lock.WaitAsync(cancellation).ConfigureAwait(false);
return _cacheTable;
}
}
///<inheritdoc/>
public void Release()
{
_lock.Release();
}
///<inheritdoc/>
public async ValueTask<CacheBucketHandle> WaitAsync(CancellationToken cancellation)
{
//try to enter the lock synchronously
if (_lock.Wait(0, CancellationToken.None))
{
return new(this, _cacheTable);
}
else
{
await _lock.WaitAsync(cancellation).ConfigureAwait(false);
return new(this, _cacheTable);
}
}
}
}
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