我正在尝试解决使用我的ImageProcessor库这里时出现的问题,当我将项目添加到缓存中时,会出现间歇性的文件访问错误。
System.IO.IOException: 由于另一个进程正在使用,因此无法访问文件“D:\home\site\wwwroot\app_data\cache\0\6\5\f\2\7\065f27fc2c8e843443d210a1e84d1ea28bbab6c4.webp”。
我编写了一个类,旨在根据哈希URL生成的密钥执行异步锁定,但似乎在实现中漏掉了一些东西。
我的锁定类
public sealed class AsyncDuplicateLock
{
/// <summary>
/// The collection of semaphore slims.
/// </summary>
private static readonly ConcurrentDictionary<object, SemaphoreSlim> SemaphoreSlims
= new ConcurrentDictionary<object, SemaphoreSlim>();
/// <summary>
/// Locks against the given key.
/// </summary>
/// <param name="key">
/// The key that identifies the current object.
/// </param>
/// <returns>
/// The disposable <see cref="Task"/>.
/// </returns>
public IDisposable Lock(object key)
{
DisposableScope releaser = new DisposableScope(
key,
s =>
{
SemaphoreSlim locker;
if (SemaphoreSlims.TryRemove(s, out locker))
{
locker.Release();
locker.Dispose();
}
});
SemaphoreSlim semaphore = SemaphoreSlims.GetOrAdd(key, new SemaphoreSlim(1, 1));
semaphore.Wait();
return releaser;
}
/// <summary>
/// Asynchronously locks against the given key.
/// </summary>
/// <param name="key">
/// The key that identifies the current object.
/// </param>
/// <returns>
/// The disposable <see cref="Task"/>.
/// </returns>
public Task<IDisposable> LockAsync(object key)
{
DisposableScope releaser = new DisposableScope(
key,
s =>
{
SemaphoreSlim locker;
if (SemaphoreSlims.TryRemove(s, out locker))
{
locker.Release();
locker.Dispose();
}
});
Task<IDisposable> releaserTask = Task.FromResult(releaser as IDisposable);
SemaphoreSlim semaphore = SemaphoreSlims.GetOrAdd(key, new SemaphoreSlim(1, 1));
Task waitTask = semaphore.WaitAsync();
return waitTask.IsCompleted
? releaserTask
: waitTask.ContinueWith(
(_, r) => (IDisposable)r,
releaser,
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
/// <summary>
/// The disposable scope.
/// </summary>
private sealed class DisposableScope : IDisposable
{
/// <summary>
/// The key
/// </summary>
private readonly object key;
/// <summary>
/// The close scope action.
/// </summary>
private readonly Action<object> closeScopeAction;
/// <summary>
/// Initializes a new instance of the <see cref="DisposableScope"/> class.
/// </summary>
/// <param name="key">
/// The key.
/// </param>
/// <param name="closeScopeAction">
/// The close scope action.
/// </param>
public DisposableScope(object key, Action<object> closeScopeAction)
{
this.key = key;
this.closeScopeAction = closeScopeAction;
}
/// <summary>
/// Disposes the scope.
/// </summary>
public void Dispose()
{
this.closeScopeAction(this.key);
}
}
}
使用 - 在 HttpModule 中
private readonly AsyncDuplicateLock locker = new AsyncDuplicateLock();
using (await this.locker.LockAsync(cachedPath))
{
// Process and save a cached image.
}
有没有人能发现我的错误所在?我担心我对某些基本概念的理解出现了误差。
该库的完整源代码存储在Github 这里
ResizeAsync
或者一般的xxxAsync
吗?我想异步使用你的库。 - Royi NamirImage.Save(stream)
没有异步重载。 - James South