我知道，如果编译器认为没有使用方法，有时可以省略方法，并且您可以通过直接在代码中引用该方法来强制编译器包含它来解决此问题。但是，在这种情况下，它似乎不起作用。
这是异常和调用堆栈：
System.ExecutionEngineException: Attempting to JIT compile method '(wrapper managed-to-native) System.Threading.Interlocked:Exchange (System.Threading.Tasks.IContinuation&,System.Threading.Tasks.IContinuation)' while running with --aot-only. See http://docs.xamarin.com/ios/about/limitations for more information.
at System.Threading.Tasks.TaskCompletionQueue`1[System.Threading.Tasks.IContinuation].TryGetNextCompletion (IContinuation& continuation) [0x00000] in <filename unknown>:0
at System.Threading.Tasks.Task.ProcessCompleteDelegates () [0x0001b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:521
at System.Threading.Tasks.Task.HandleGenericException (System.AggregateException e) [0x0001a] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:563
at System.Threading.Tasks.Task.TrySetException (System.AggregateException aggregate) [0x0003e] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:440
at System.Threading.Tasks.TaskCompletionSource`1[System.Net.WebResponse].TrySetException (IEnumerable`1 exceptions) [0x00000] in <filename unknown>:0
at System.Threading.Tasks.TaskCompletionSource`1[System.Net.WebResponse].SetException (IEnumerable`1 exceptions) [0x00000] in <filename unknown>:0
at System.Threading.Tasks.TaskCompletionSource`1[System.Net.WebResponse].SetException (System.Exception exception) [0x00000] in <filename unknown>:0
at System.Threading.Tasks.TaskFactory`1[System.Net.WebResponse].InnerInvoke (System.Threading.Tasks.TaskCompletionSource`1 tcs, System.Func`2 endMethod, IAsyncResult l) [0x00000] in <filename unknown>:0
at System.Threading.Tasks.TaskFactory`1+<FromAsyncBeginEnd>c__AnonStorey21[System.Net.WebResponse].<>m__15 (IAsyncResult l) [0x00000] in <filename unknown>:0
at Vistian.Net.Http.HttpRequestProcessor+<BeginGetResponse>c__AnonStorey3.<>m__5 (IAsyncResult result) [0x00082] in /Users/martinstafford/Projects/Vistian/vistian/common/Vistian.Net/trunk/Vistian.Net.Portable/Http/HttpRequestProcessor.cs:441
at System.Net.WebAsyncResult.CB (System.Object unused) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebAsyncResult.cs:148
我尝试在有问题的类的构造函数中包含这一行，但错误仍然存在：
object dummy = System.Threading.Interlocked.Exchange( ref dummyLock, new object());
这是围绕错误的代码。抱歉有这么多，但它在上下文中得到它。调用“回调”时抛出异常 - 其中任何一个。如您所见，我正在尝试为包含 GetRequestStream 和 GetResponse 的两个异步操作的类实现异步编程模型：
public static IAsyncResult BeginGetResponse(AsyncCallback callback, object state)
{
var requestProcessor = state as HttpRequestProcessor;
// create the Uri of the Host and Path in the request
// and use it to create a HttpWebRequest
Uri u = new Uri(new Uri(requestProcessor.Request.Host), requestProcessor.Request.Path);
requestProcessor.HttpWebRequest = WebRequest.Create(u) as HttpWebRequest;
// set up the header of the HttpWebRequest
requestProcessor.SetupHeader(requestProcessor.HttpWebRequest, requestProcessor.Request);
requestProcessor.WebResponse = null;
requestProcessor.RaisedException = null;
// set up an event to be used to 'timeout' the forthcoming async process
var syncRef = new System.Threading.AutoResetEvent(false);
System.Diagnostics.Debug.WriteLine(string.Format("HttpRequestProcessor.BeginGetResponse: started method={0}", requestProcessor.Request.Method));
// perform the request using the Async method
// GET and POST requests are processed differently
if (requestProcessor.Request.Method == HttpMethod.POST)
{
// create the request content using the serialiser
var bytes = requestProcessor.Encoder.Encode(requestProcessor.Request.Data, requestProcessor.Request.ContentType);
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: BeginGetRequestStream started");
// start the async process by adding the content to the request
requestProcessor.HttpWebRequest.BeginGetRequestStream((IAsyncResult result) =>
{
// the asyncronous Get RequestStream has finished in some way
// complete the Get RequestStream process by calling EndGetRequestStream
// get the HttpWebRequest provided in the 'state' parameter and
// use it to call EndGetRequestStream
var request = result.AsyncState as HttpWebRequest;
try
{
// fill the request stream with the content
using (Stream requestStream = request.EndGetRequestStream(result))
{
requestStream.Write(bytes, 0, bytes.Length);
}
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: EndGetRequestStream");
}
catch (Exception e)
{
// if the filling of the request stream fails, finish the Async process here
System.Diagnostics.Debug.WriteLine(string.Format("HttpRequestProcessor.BeginGetResponse: EndGetRequestSteam failed. Uri={0}", request.RequestUri));
// remember the exception, to be picked up by the subsequent call in to EndGetResponse
requestProcessor.RaisedException = e;
// clear the timeout event to indicate the async process has finished
syncRef.Set();
// call the callback as the async process is finished
callback(new AsyncResult(requestProcessor, true));
return;
}
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: BeginGetResponse started");
// the HttpWebRequest has the request content in it
// send the request and get the response
request.BeginGetResponse((IAsyncResult responseResult) =>
{
// the Async process GetResponse has finished in some way
// get the HttpWebRequest provided as a parameter and use it
// to complete the GetRespone process
HttpWebRequest req = responseResult.AsyncState as HttpWebRequest;
try
{
requestProcessor.WebResponse = req.EndGetResponse(responseResult);
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: EndGetResponse");
}
catch (Exception e)
{
// if getting the response fails, catch and remember the exception
// for the subsequent call in to EndGetResponse
System.Diagnostics.Debug.WriteLine(string.Format("HttpRequestProcessor.BeginGetResponse: EndGetResponse failed. Uri={0}", req.RequestUri));
requestProcessor.RaisedException = e;
}
// clear the timeout timer event
syncRef.Set();
// call the async callback
callback(new AsyncResult(requestProcessor, true));
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: POST callback complete");
}, request);
}, requestProcessor.HttpWebRequest);
}
else
{
requestProcessor.HttpWebRequest.BeginGetResponse((IAsyncResult responseResult) =>
{
HttpWebRequest req = responseResult.AsyncState as HttpWebRequest;
try
{
requestProcessor.WebResponse = req.EndGetResponse(responseResult);
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: EndGetResponse");
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine(string.Format("HttpRequestProcessor.BeginGetResponse: EndGetResponse failed. Uri={0}", req.RequestUri));
requestProcessor.RaisedException = e;
}
syncRef.Set();
callback(new AsyncResult(requestProcessor, true));
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: GET callback complete");
}, requestProcessor.HttpWebRequest);
}
// wait for the async process to finish or timeout
if (!syncRef.WaitOne(requestProcessor.Request.Timeout))
{
// async process has time out
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.BeginGetResponse: BeginGetStreamRequest timed out");
// abort the async process and create and remember an exception
// to be picked up by the call in the EndGetResponse
requestProcessor.HttpWebRequest.Abort();
requestProcessor.RaisedException = new TimeoutException("loading request stream timed out");
}
return new AsyncResult(requestProcessor, false);
}
public static WebResponse EndGetResponse(IAsyncResult result)
{
System.Diagnostics.Debug.WriteLine("HttpRequestProcessor.EndGetResponse:");
var requestProcessor = result.AsyncState as HttpRequestProcessor;
if (requestProcessor.RaisedException != null)
{
throw requestProcessor.RaisedException;
}
return requestProcessor.WebResponse;
}