/// <summary>
/// Starts the link control reader; should be called by link implementation after the link is connected.
/// </summary>
/// <param name="ctrlReader">CtrlReader instance used to read from the link.</param>
/// <returns>A task that can be awaited on.</returns>
protected async Task StartLinkAsync(CtrlReader ctrlReader)
{
// Check to make sure the link has been cleaned up, if it was used previously
if (this.readCancellationSource != null)
{
throw new InvalidOperationException("Invalid state; CleanupLink() did not run before link re-use");
}
this.readCancellationSource = new CancellationTokenSource();
// ConfigureAwait so that it will not run on same thread
await this.CreateReadingTask(ctrlReader, this.readCancellationSource.Token).ConfigureAwait(false);
this.IsConnected = true;
this.OnCtrlLinkConnected();
await this.SendActiveSubscriptions();
}
/// <summary>
/// Creates a reading task.
/// </summary>
/// <param name="ctrlReader">CtrlReader instance used to read from the link.</param>
/// <param name="cts">Cancellation token for the read class.</param>
/// <returns>Task that can be awaited on.</returns>
private Task CreateReadingTask(CtrlReader ctrlReader, CancellationToken cts)
{
return(Task.Factory.StartNew(
async() =>
{
try
{
Message msg = null;
// We need to read at least one byte:
uint readBytes = 1;
while (!cts.IsCancellationRequested)
{
if (msg == null)
{
msg = new Message();
}
uint byteCount = await ctrlReader.LoadAsync(readBytes);
// Unless we figure out below how many bytes we need, let's set it to the default,
// safe value of one byte. It may have been changed to something bigger
// if we were reading the rest of a larger message.
readBytes = 1;
#if DEBUG2
Debug.WriteLine("Read " + byteCount + " bytes");
#endif
if (byteCount == 0)
{
Debug.WriteLine("Control link closed in reader.");
this.LinkClosed();
return;
}
int reqBytes = 0;
try
{
reqBytes = msg.DeserializeBaseMessage(ctrlReader);
}
catch (Protocol.ProtoException e)
{
Debug.WriteLine("Protocol exception while deserializing base message: " + e);
this.OnCtrlLinkError(e);
this.LinkClosed();
return;
}
if (reqBytes < 1)
{
#if DEBUG2
Debug.WriteLine("Received complete message - delivering");
#endif
CtrlMessageReceived(msg);
msg = null;
}
else
{
#if DEBUG2
Debug.WriteLine("DeserializeBase needs " + reqBytes + " bytes more.");
#endif
// Now we know exactly how many bytes we need.
// We may need more than that, but this is the "at least this many bytes" value,
// so it is safe to read this much. If it is not enough,
// we will have a better idea the next time we read something.
readBytes = ( uint )reqBytes;
}
}
}
catch (Exception e)
{
Debug.WriteLine("Unknown exception inside read loop: " + e);
this.OnCtrlLinkError(e);
this.LinkClosed();
return;
}
},
cts));
}
