为什么设置RequestInitializationTimeout属性？

Question

什么是HttpTransportElement的RequestInitializationTimeout？MSDN说:

获取或设置时间跨度,该时间跨度指定在超时之前请求初始化必须完成的时间.

究竟什么是"请求初始化"？为什么我要设置此属性？

Answer 1

没有关于RequestInitializationTimeout.

源代码中有SharedHttpTransportManager.IsCompatible关于RequestInitializationTimeout检查的注释：

// We are NOT checking the RequestInitializationTimeout here since the HttpChannelListener should be handle them
// individually. However, some of the scenarios might be impacted, e.g., if we have one endpoint with high RequestInitializationTimeout
// and the other is just normal, the first endpoint might be occupying all the receiving loops, then the requests to the normal endpoint
// will experience timeout issues. The mitigation for this issue is that customers should be able to increase the MaxPendingAccepts number.

如果我们检查TimeoutException它分配给与内部requestException一起传递HttpRequestContext.SetMessage(message, requestException)的OnParseComplete，我们可以看到：

// We are NOT checking the RequestInitializationTimeout here since the HttpChannelListener should be handle them
// individually. However, some of the scenarios might be impacted, e.g., if we have one endpoint with high RequestInitializationTimeout
// and the other is just normal, the first endpoint might be occupying all the receiving loops, then the requests to the normal endpoint
// will experience timeout issues. The mitigation for this issue is that customers should be able to increase the MaxPendingAccepts number.

并且关于异常消息是：SR.RequestInitializationTimeoutReached System.Private.ServiceModel

The initialization process of the request message timed out after {0}. To increase this quota, use the '{1}' property on the '{2}'.

这将被格式化为这样的：

The initialization process of the request message timed out after 00:00:10. To increase this quota, use the 'RequestInitializationTimeout' property on the 'HttpTransportBindingElement'.

tl;博士

如果我们按照源代码，我们可以在里面找到它的用法EmptyHttpPipeline。

承建商 EmptyHttpPipeline.EmptyHttpPipeline

如果有一个RequestInitializationTimeout TimeSpan（而不是默认00:00:00禁用它），一个IOThreadTimer设置与dueTime设置到TimeSpan蜱，在回调（实际对象）作为。OnRequestInitializationTimeout ActionthisEmptyHttpPipelinecallbackState

new TimeoutException(SR.GetString(
    SR.RequestInitializationTimeoutReached,
    this.HttpRequestContext.Listener.RequestInitializationTimeout,
    "RequestInitializationTimeout",
    typeof(HttpTransportBindingElement).Name))

什么时候查的？

当它的检查EmptyHttpPipeline.OnParseComplete方法是由试图取消被叫requestInitializationTimer。如果有一个计时器并且它之前被取消或过期，它会创建一个TimeoutException它分配给requestException它的 ，它与HttpPipeline.HttpRequestContext.SetMessage一起传递给message：

The initialization process of the request message timed out after {0}. To increase this quota, use the '{1}' property on the '{2}'.

该OnParseComplete方法被称为内EnqueueMessageAsyncResult.CompleteParseAndEnqueue使用内部的方法。该调用时被创建对象和它终止内部。HandleParseIncomingMessage AsyncCallbackEnqueueMessageAsyncResult.EndEnqueueMessageAsyncResultEmptyHttpPipeline.BeginProcessInboundRequestEmptyHttpPipeline.EndProcessInboundRequest

BeginProcessInboundRequest 和 EndProcessInboundRequest

The initialization process of the request message timed out after 00:00:10. To increase this quota, use the 'RequestInitializationTimeout' property on the 'HttpTransportBindingElement'.

EnqueueMessageAsyncResult.CompleteParseAndEnqueue

if (this.httpRequestContext.Listener.RequestInitializationTimeout != HttpTransportDefaults.RequestInitializationTimeout)
{
    this.requestInitializationTimer = new IOThreadTimer(onRequestInitializationTimeout, this, false);
    this.requestInitializationTimer.Set(this.httpRequestContext.Listener.RequestInitializationTimeout);
}

它是如何被检查和取消的？

正在使用该CancelRequestInitializationTimer方法对其进行检查，如果没有设置计时器，则仅返回 true；如果它之前被取消，它返回false，否则它调用IOThreadTimer.Cancel方法来检查并返回true，如果它被取消，或者如果计时器过期则返回false 。

EmptyHttpPipeline.CancelRequestInitializationTimer

protected override void OnParseComplete(Message message, Exception requestException)
{
    if (!this.CancelRequestInitializationTimer() && requestException == null)
    {
        requestException = FxTrace.Exception.AsError(new TimeoutException(SR.GetString(
                                SR.RequestInitializationTimeoutReached,
                                this.HttpRequestContext.Listener.RequestInitializationTimeout,
                                "RequestInitializationTimeout",
                                typeof(HttpTransportBindingElement).Name)));
    }

    this.HttpRequestContext.SetMessage(message, requestException);
}

实际上被取消的是什么？

在OnRequestInitializationTimeout方法内部，我们可以看到它取消了HttpPipeline中止的HttpPipeline.httpRequestContext：

EmptyHttpPipeline.OnRequestInitializationTimeout

internal override IAsyncResult BeginProcessInboundRequest(
    ReplyChannelAcceptor replyChannelAcceptor,
    Action dequeuedCallback,
    AsyncCallback callback,
    object state)
{
    this.TraceBeginProcessInboundRequestStart();
    return new EnqueueMessageAsyncResult(replyChannelAcceptor, dequeuedCallback, this, callback, state);
}

internal override void EndProcessInboundRequest(IAsyncResult result)
{
    // It will trigger HandleParseIncomingMessage AsyncCallback,
    // that will call CompleteParseAndEnqueue
    EnqueueMessageAsyncResult.End(result);
    this.TraceProcessInboundRequestStop();
}

HttpPipeline.Cancel

void CompleteParseAndEnqueue(IAsyncResult result)
{
    using (DiagnosticUtility.ShouldUseActivity ? ServiceModelActivity.BoundOperation(this.CallbackActivity) : null)
    {
        Exception requestException;
        Message message = this.pipeline.EndParseIncomingMesssage(result, out requestException);
        if ((message == null) && (requestException == null))
        {
            throw FxTrace.Exception.AsError(
                    new ProtocolException(
                        SR.GetString(SR.MessageXmlProtocolError),
                        new XmlException(SR.GetString(SR.MessageIsEmpty))));
        }

        // Here the EmptyHttpPipeline.OnParseComplete is being invoked
        this.pipeline.OnParseComplete(message, requestException);
        this.acceptor.Enqueue(this.pipeline.HttpRequestContext, this.dequeuedCallback, true);
    }
}

我们什么时候得到一个EmptyHttpPipeline对象？

EmptyHttpPipeline如果我们transportIntegrationHandler = null使用HttpPipeline.CreateHttpPipeline接受 aTransportIntegrationHandler并且没有的静态设置，我们会得到一个HttpRequestContext.HttpMessagesSupported：

protected bool CancelRequestInitializationTimer()
{
    if (this.requestInitializationTimer == null)
    {
        return true;
    }

    if (this.requestInitializationTimerCancelled)
    {
        return false;
    }

    bool result = this.requestInitializationTimer.Cancel();
    this.requestInitializationTimerCancelled = true;

    return result;
}

在CreateHttpPipeline被称为上HttpRequestContext.InitializeHttpPipeline：

HttpRequestContext.InitializeHttpPipeline

static void OnRequestInitializationTimeout(object obj)
{
    Fx.Assert(obj != null, "obj should not be null.");
    HttpPipeline thisPtr = (HttpPipeline)obj;
    thisPtr.Cancel();
}

在使用内部调用HttpRequestContext requestContext（在HttpContextReceivedAsyncResult构造函数中传递）HttpContextReceivedAsyncResult<TListenerChannel>.ProcessHttpContextAsyncHttpChannelListener<TListenerChannel>.transportIntegrationHandler

HttpContextReceivedAsyncResult<TListenerChannel>.ProcessHttpContextAsync

public virtual void Cancel()
{
  this.httpRequestContext.Abort();
}

结论

所有这些都让我们得出结论，当 aHttpPipeline创建时没有 aTransportIntegrationHandler并且没有HttpMessagesSupportedfor HttpRequestContext，那么新EmptyHttpPipeline对象将为/设置超时（如果RequestInitializationTimeout设置）， 并在使用inside设置消息时设置异常。BeginProcessInboundRequestEndProcessInboundRequestEmptyHttpPipeline.HttpRequestContext.SetMessageEmptyHttpPipeline.OnParseComplete