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namespace System.Web.Mvc.Async {
using System;
using System.Threading;
internal static class AsyncUtil {
public static void WaitForAsyncResultCompletion(IAsyncResult asyncResult, HttpApplication app) {
// based on HttpServerUtility.ExecuteInternal()
if (!asyncResult.IsCompleted) {
// suspend app lock while waiting, else might deadlock
bool needToRelock = false;
try {
// .NET 2.0+ will not allow a ThreadAbortException to be thrown while a
// thread is inside a finally block, so this pattern ensures that the
// value of 'needToRelock' is correct.
try { }
finally {
Monitor.Exit(app);
needToRelock = true;
}
WaitHandle waitHandle = asyncResult.AsyncWaitHandle;
if (waitHandle != null) {
waitHandle.WaitOne();
}
else {
while (!asyncResult.IsCompleted) {
Thread.Sleep(1);
}
}
}
finally {
if (needToRelock) {
Monitor.Enter(app);
}
}
}
}
public static AsyncCallback WrapCallbackForSynchronizedExecution(AsyncCallback callback, SynchronizationContext syncContext) {
if (callback == null || syncContext == null) {
return callback;
}
AsyncCallback newCallback = delegate(IAsyncResult asyncResult) {
if (asyncResult.CompletedSynchronously) {
callback(asyncResult);
}
else {
// Only take the application lock if this request completed asynchronously,
// else we might end up in a deadlock situation.
syncContext.Sync(() => callback(asyncResult));
}
};
return newCallback;
}
}
}
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