private void PollingLoop(IConnection connection, string data, Action initializeCallback, Action<Exception> errorCallback, bool raiseReconnect = false)
{
string url = connection.Url;
var reconnectTokenSource = new CancellationTokenSource();
int reconnectFired = 0;
// This is only necessary for the initial request where initializeCallback and errorCallback are non-null
int callbackFired = 0;
if (connection.MessageId == null)
{
url += "connect";
}
else if (raiseReconnect)
{
url += "reconnect";
connection.State = ConnectionState.Reconnecting;
}
url += GetReceiveQueryString(connection, data);
Debug.WriteLine("LP: {0}", (object)url);
_httpClient.PostAsync(url, PrepareRequest(connection)).ContinueWith(task =>
{
// Clear the pending request
connection.Items.Remove(HttpRequestKey);
bool shouldRaiseReconnect = false;
bool disconnectedReceived = false;
try
{
if (!task.IsFaulted)
{
if (raiseReconnect)
{
// If the timeout for the reconnect hasn't fired as yet just fire the
// event here before any incoming messages are processed
FireReconnected(connection, reconnectTokenSource, ref reconnectFired);
}
// Get the response
var raw = task.Result.ReadAsString();
Debug.WriteLine("LP Receive: {0}", (object)raw);
ProcessResponse(connection, raw, out shouldRaiseReconnect, out disconnectedReceived);
}
}
finally
{
if (disconnectedReceived)
{
connection.Stop();
}
else
{
bool requestAborted = false;
if (task.IsFaulted)
{
// Cancel the previous reconnect event
reconnectTokenSource.Cancel();
// Raise the reconnect event if we successfully reconnect after failing
shouldRaiseReconnect = true;
// Get the underlying exception
Exception exception = task.Exception.GetBaseException();
// If the error callback isn't null then raise it and don't continue polling
if (errorCallback != null &&
Interlocked.Exchange(ref callbackFired, 1) == 0)
{
// Call the callback
errorCallback(exception);
}
else
{
// Figure out if the request was aborted
requestAborted = IsRequestAborted(exception);
// Sometimes a connection might have been closed by the server before we get to write anything
// so just try again and don't raise OnError.
if (!requestAborted && !(exception is IOException))
{
// Raise on error
connection.OnError(exception);
// If the connection is still active after raising the error event wait for 2 seconds
// before polling again so we aren't hammering the server
TaskAsyncHelper.Delay(_errorDelay).Then(() =>
{
if (!connection.IsDisconnecting())
{
PollingLoop(connection,
data,
initializeCallback: null,
errorCallback: null,
raiseReconnect: shouldRaiseReconnect);
}
});
}
}
}
else
{
if (!connection.IsDisconnecting())
{
// Continue polling if there was no error
PollingLoop(connection,
data,
initializeCallback: null,
errorCallback: null,
raiseReconnect: shouldRaiseReconnect);
}
}
}
}
});
if (initializeCallback != null)
{
if (Interlocked.Exchange(ref callbackFired, 1) == 0)
{
initializeCallback();
}
}
if (raiseReconnect)
{
TaskAsyncHelper.Delay(ReconnectDelay).Then(() =>
{
// Fire the reconnect event after the delay. This gives the
FireReconnected(connection, reconnectTokenSource, ref reconnectFired);
});
}
}
private void Reconnect(IConnection connection, string data)
{
if (connection.IsDisconnecting())
{
return;
}
// Wait for a bit before reconnecting
TaskAsyncHelper.Delay(ReconnectDelay).Then(() =>
{
// Now attempt a reconnect
OpenConnection(connection, data, initializeCallback: null, errorCallback: null);
});
}
