C# WebApi请求中的取消
关于使用CancellationToken取消WebApi请求,有几种参考资料,例如(该概念似乎适用于所有最新版本):C# WebApi请求中的取消,c#,asp.net-web-api,cancellation-token,C#,Asp.net Web Api,Cancellation Token,关于使用CancellationToken取消WebApi请求,有几种参考资料,例如(该概念似乎适用于所有最新版本): 现在我还了解到,对于HTTP连接,通常不会在每次发送新请求时打开和关闭TCP连接,但通常会保持TCP连接打开,至少这是我从MDN中理解本文的方式: 所以我的问题是: 如果我正在执行来自C#的HTTP请求,是否每次都会建立并关闭底层TCP连接,这样机制基本上就是一个TCP连接,并且服务器可以在令牌中请求取消 那么,这是否最终取决于我总是为每个请求打开一个新的TCP连接?或
那么,这是否最终取决于我总是为每个请求打开一个新的TCP连接?或者,在TCP连接无法关闭的情况下,是否还有其他方法也可以使用?以下是Github中HttpWebrequest.Abort()方法的源代码
private void Abort(Exception exception, int abortState)
{
GlobalLog.ThreadContract(ThreadKinds.Unknown, "HttpWebRequest#" + ValidationHelper.HashString(this) + "::Abort()");
if (Logging.On) Logging.Enter(Logging.Web, this, "Abort", (exception == null? "" : exception.Message));
if(Interlocked.CompareExchange(ref m_Aborted, abortState, 0) == 0) // public abort will never drain streams
{
GlobalLog.Print("HttpWebRequest#" + ValidationHelper.HashString(this) + "::Abort() - " + exception);
NetworkingPerfCounters.Instance.Increment(NetworkingPerfCounterName.HttpWebRequestAborted);
m_OnceFailed = true;
CancelTimer();
WebException webException = exception as WebException;
if (exception == null)
{
webException = new WebException(NetRes.GetWebStatusString("net_requestaborted", WebExceptionStatus.RequestCanceled), WebExceptionStatus.RequestCanceled);
}
else if (webException == null)
{
webException = new WebException(NetRes.GetWebStatusString("net_requestaborted", WebExceptionStatus.RequestCanceled), exception, WebExceptionStatus.RequestCanceled, _HttpResponse);
}
try
{
// Want to make sure that other threads see that we're aborted before they set an abort delegate, or that we see
// the delegate if they might have missed that we're aborted.
Thread.MemoryBarrier();
HttpAbortDelegate abortDelegate = _AbortDelegate;
if (abortDelegate == null || abortDelegate(this, webException))
{
// We don't have a connection associated with this request
SetResponse(webException);
}
else
{
// In case we don't call SetResponse(), make sure to complete the lazy async result
// objects. abortDelegate() may not end up in a code path that would complete these
// objects.
LazyAsyncResult writeAResult = null;
LazyAsyncResult readAResult = null;
if (!Async)
{
lock (this)
{
writeAResult = _WriteAResult;
readAResult = _ReadAResult;
}
}
if (writeAResult != null)
writeAResult.InvokeCallback(webException);
if (readAResult != null)
readAResult.InvokeCallback(webException);
}
if (!Async)
{
LazyAsyncResult chkConnectionAsyncResult = ConnectionAsyncResult;
LazyAsyncResult chkReaderAsyncResult = ConnectionReaderAsyncResult;
if (chkConnectionAsyncResult != null)
chkConnectionAsyncResult.InvokeCallback(webException);
if (chkReaderAsyncResult != null)
chkReaderAsyncResult.InvokeCallback(webException);
}
if (this.IsWebSocketRequest && this.ServicePoint != null)
{
this.ServicePoint.CloseConnectionGroup(this.ConnectionGroupName);
}
}
catch (InternalException)
{
}
}
if(Logging.On)Logging.Exit(Logging.Web, this, "Abort", "");
}
这清楚地表明TCP连接正在关闭。服务器以自己的方式响应关闭的TCP端口。
链接:在进行HTTP请求-响应交换之后,您不必担心连接是否关闭,因为这对取消机制没有影响。确实有影响的是,在HTTP请求-响应交换过程中,连接被关闭,因为如果服务器端处理取消令牌,这会触发取消服务器端的请求处理。因此,换句话说,如果在发送响应之前关闭了连接,而不管连接是哪种类型(保持活动状态或每次交换),这就是服务器启动取消过程的原因