非同期プログラミングを使用して画像を処理する HttpModule に速度向上を追加しようとしています。
確かにパフォーマンスが向上しているように見えますが、提供されたツールを正しく使用していることを確認したいと思います。
キューを正しく処理していないことが特に心配です。
私が取っているアプローチ。
- ConcurrentQueue を初期化する
- AddOnBeginRequestAsync の BeginEventHandler のキューに ProcessImage メソッドを追加します。
- AddOnBeginRequestAsync の EndEventHandler でキューを処理する
コードがたくさんあるので、前もってお詫びしますが、非同期プログラミングは難しいです:
田畑
/// <summary>
/// The thread safe fifo queue.
/// </summary>
private static ConcurrentQueue<Action> imageOperations;
/// <summary>
/// A value indicating whether the application has started.
/// </summary>
private static bool hasAppStarted = false;
httpモジュール初期化
/// <summary>
/// Initializes a module and prepares it to handle requests.
/// </summary>
/// <param name="context">
/// An <see cref="T:System.Web.HttpApplication"/> that provides
/// access to the methods, properties, and events common to all
/// application objects within an ASP.NET application
/// </param>
public void Init(HttpApplication context)
{
if (!hasAppStarted)
{
lock (SyncRoot)
{
if (!hasAppStarted)
{
imageOperations = new ConcurrentQueue<Action>();
DiskCache.CreateCacheDirectories();
hasAppStarted = true;
}
}
}
context.AddOnBeginRequestAsync(OnBeginAsync, OnEndAsync);
context.PreSendRequestHeaders += this.ContextPreSendRequestHeaders;
}
イベントハンドラ
/// <summary>
/// The <see cref="T:System.Web.BeginEventHandler"/> that starts
/// asynchronous processing
/// of the <see cref="T:System.Web.HttpApplication.BeginRequest"/>.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">
/// An <see cref="T:System.EventArgs">EventArgs</see> that contains
/// the event data.
/// </param>
/// <param name="cb">
/// The delegate to call when the asynchronous method call is complete.
/// If cb is null, the delegate is not called.
/// </param>
/// <param name="extraData">
/// Any additional data needed to process the request.
/// </param>
/// <returns></returns>
IAsyncResult OnBeginAsync(
object sender, EventArgs e, AsyncCallback cb, object extraData)
{
HttpContext context = ((HttpApplication)sender).Context;
EnqueueDelegate enqueueDelegate = new EnqueueDelegate(Enqueue);
return enqueueDelegate.BeginInvoke(context, cb, extraData);
}
/// <summary>
/// The method that handles asynchronous events such as application events.
/// </summary>
/// <param name="result">
/// The <see cref="T:System.IAsyncResult"/> that is the result of the
/// <see cref="T:System.Web.BeginEventHandler"/> operation.
/// </param>
public void OnEndAsync(IAsyncResult result)
{
// An action to consume the ConcurrentQueue.
Action action = () =>
{
Action op;
while (imageOperations.TryDequeue(out op))
{
op();
}
};
// Start 4 concurrent consuming actions.
Parallel.Invoke(action, action, action, action);
}
委任して処理する
/// <summary>
/// The delegate void representing the Enqueue method.
/// </summary>
/// <param name="context">
/// the <see cref="T:System.Web.HttpContext">HttpContext</see> object that
/// provides references to the intrinsic server objects
/// </param>
private delegate void EnqueueDelegate(HttpContext context);
/// <summary>
/// Adds the method to the queue.
/// </summary>
/// <param name="context">
/// the <see cref="T:System.Web.HttpContext">HttpContext</see> object that
/// provides references to the intrinsic server objects
/// </param>
private void Enqueue(HttpContext context)
{
imageOperations.Enqueue(() => ProcessImage(context));
}