private void DownloadAsync <T>(RequestState <T> requestState, Exception exception)
{
if (!exception.IsNull() && RetryWaitDuration.HasValue)
{
Thread.Sleep(RetryWaitDuration.Value);
}
if (requestState.Retry-- > 0)
{
requestState.Clean();
requestState.Request = (HttpWebRequest)WebRequest.Create(requestState.CrawlStep.Uri);
requestState.Request.Method = requestState.Method.ToString();
SetDefaultRequestProperties(requestState.Request);
IAsyncResult asyncResult = requestState.Request.BeginGetResponse(null, requestState);
asyncResult.FromAsync((ia, isTimeout) =>
{
if (isTimeout)
{
DownloadAsync(requestState, new TimeoutException("Connection Timeout"));
}
else
{
ResponseCallback <T>(ia);
}
}, ConnectionTimeout);
}
else
{
requestState.CallComplete(null, exception);
}
}
public static void CopyToStreamAsync(this Stream source, Stream destination,
Action <Stream, Stream, Exception> completed, Action <uint> progress,
uint bufferSize, uint?maximumDownloadSize, TimeSpan?timeout)
{
byte[] buffer = new byte[bufferSize];
Action <Exception> done = exception =>
{
if (completed != null)
{
completed(source, destination, exception);
}
};
int maxDownloadSize = maximumDownloadSize.HasValue
? (int)maximumDownloadSize.Value
: int.MaxValue;
int bytesDownloaded = 0;
IAsyncResult asyncResult = source.BeginRead(buffer, 0, new[] { maxDownloadSize, buffer.Length }.Min(), null, null);
Action <IAsyncResult, bool> endRead = null;
endRead = (innerAsyncResult, innerIsTimedOut) =>
{
try
{
int bytesRead = source.EndRead(innerAsyncResult);
if (innerIsTimedOut)
{
done(new TimeoutException());
}
int bytesToWrite = new[] { maxDownloadSize - bytesDownloaded, buffer.Length, bytesRead }.Min();
destination.Write(buffer, 0, bytesToWrite);
bytesDownloaded += bytesToWrite;
if (!progress.IsNull() && bytesToWrite > 0)
{
progress((uint)bytesDownloaded);
}
if (bytesToWrite == bytesRead && bytesToWrite > 0)
{
asyncResult = source.BeginRead(buffer, 0, new[] { maxDownloadSize, buffer.Length }.Min(), null, null);
// ReSharper disable PossibleNullReferenceException
// ReSharper disable AccessToModifiedClosure
asyncResult.FromAsync((ia, isTimeout) => endRead(ia, isTimeout), timeout);
// ReSharper restore AccessToModifiedClosure
// ReSharper restore PossibleNullReferenceException
}
else
{
done(null);
}
}
catch (Exception exc)
{
done(exc);
}
};
asyncResult.FromAsync((ia, isTimeout) => endRead(ia, isTimeout), timeout);
}
