static IObservable <TResult> AbortableDeferredAsyncRequest <TResult>(Func <AsyncCallback, object, IAsyncResult> begin, Func <IAsyncResult, TResult> end, WebRequest request)
{
var result = Observable.Create <TResult>(observer => {
var isCompleted = -1;
var subscription = Observable.FromAsyncPattern <TResult>(begin,
ar => {
try
{
Interlocked.Increment(ref isCompleted);
return(end(ar));
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.RequestCanceled)
{
return(default(TResult));
}
throw;
}
})()
.Subscribe(observer);
return(Disposable.Create(() => {
if (Interlocked.Increment(ref isCompleted) == 0)
{
subscription.Dispose();
request.Abort();
}
}));
});
return(result);
}
private static IObservable <TResult> AbortableDeferredAsyncRequest <TResult>(Func <AsyncCallback, object, IAsyncResult> begin, Func <IAsyncResult, TResult> end, WebRequest request)
{
return(Observable.Create <TResult>(delegate(IObserver <TResult> observer)
{
int isCompleted = -1;
IDisposable subscription = Observable.FromAsyncPattern <TResult>(begin, delegate(IAsyncResult ar)
{
TResult result;
try
{
Interlocked.Increment(ref isCompleted);
result = end(ar);
}
catch (WebException ex)
{
if (ex.Status != WebExceptionStatus.RequestCanceled)
{
throw;
}
result = default(TResult);
}
return result;
})().Subscribe(observer);
return Disposable.Create(delegate
{
if (Interlocked.Increment(ref isCompleted) == 0)
{
subscription.Dispose();
request.Abort();
}
});
}));
}
