static unsafe void FinishOverlappedAsynchronously(SafeObjectHandle handle, PinnedStruct <OVERLAPPED> overlapped,
ManualResetEvent finishedEvent, TaskCompletionSource <int> completionSource, CancellationToken cancellationToken)
{
var alreadyFinished = false;
var lockObject = new object();
WaitOrTimerCallback callback = (state, timedOut) =>
{
var overlappedState = (OverlappedState)state;
lock (lockObject)
{
if (alreadyFinished)
{
return;
}
overlappedState.Unregister();
if (overlappedState.IsCancellation || cancellationToken.IsCancellationRequested)
{
CancelIoEx(handle, (OVERLAPPED *)overlapped.Pointer);
completionSource.SetCanceled();
}
else
{
int bytesReturned;
var overlappedResult = GetOverlappedResult(handle, (OVERLAPPED *)overlapped.Pointer,
out bytesReturned, false);
overlapped.Dispose();
finishedEvent.Dispose();
if (overlappedResult)
{
completionSource.SetResult(bytesReturned);
}
else
{
SetFromLastWin32Exception(completionSource);
}
}
alreadyFinished = true;
}
};
lock (lockObject)
{
var finishedState = new OverlappedState(false);
var cancelledState = new OverlappedState(true);
var finishedWait = ThreadPool.RegisterWaitForSingleObject(finishedEvent, callback, finishedState, -1, true);
cancelledState.OtherRegistration = finishedWait;
if (cancellationToken != CancellationToken.None)
{
var cancelledWait = ThreadPool.RegisterWaitForSingleObject(cancellationToken.WaitHandle,
callback,
cancelledState, -1, true);
finishedState.OtherRegistration = cancelledWait;
}
}
}
static unsafe bool FinishOverlappedSynchronously(SafeObjectHandle handle, CancellationToken cancellationToken,
PinnedStruct <OVERLAPPED> overlapped, TaskCompletionSource <int> completionSource, bool nativeMethodResult)
{
if (!nativeMethodResult)
{
var error = Marshal.GetLastWin32Error();
if (error != ErrorIoPending)
{
if (cancellationToken.IsCancellationRequested)
{
completionSource.SetCanceled();
}
else
{
SetFromLastWin32Exception(completionSource);
}
return(true);
}
// Async IO in progress
return(false);
}
int pBytesReturned;
GetOverlappedResult(handle, (OVERLAPPED *)overlapped.Pointer,
out pBytesReturned, false);
if (cancellationToken.IsCancellationRequested)
{
completionSource.SetCanceled();
}
else
{
completionSource.SetResult(pBytesReturned);
}
return(true);
}
