protected async Task CheckPendingMessages(string endPointID)
{
ASSERT(!string.IsNullOrWhiteSpace(endPointID), $"Missing parameter '{nameof(endPointID)}");
// Is this endpoint registered against me ?
lock ( Locker )
{
if (!RegisteredEndpoints.ContainsKey(endPointID))
{
// No -> No need to continue
return;
}
}
var messages = await RestoreMessages(endPointID);
if (messages == null)
{
// No messages available for this endpoint
return;
}
IEndPoint endPoint;
lock ( Locker )
{
endPoint = RegisteredEndpoints.TryGet(endPointID);
if (endPoint == null)
{
// endPoint was unregistered in the mean-time (nb: should not happen often ...)
goto PUSH_MESSAGES_BACK;
}
else if (endPoint.IsOneShot)
{
// Unregister this endpoint before sending the messages
var rc = RegisteredEndpoints.Remove(endPointID);
ASSERT(rc, $"Could not unregister endpoint '{endPointID}'");
goto SEND_MESSAGES;
}
else // not one-shot
{
goto SEND_MESSAGES;
}
}
#pragma warning disable 0162
FAIL("Unreachable code reached ...");
#pragma warning restore 0162
SEND_MESSAGES:
ASSERT(endPoint != null, $"Logic error: '{nameof(endPoint)}' is supposed to be set here");
await endPoint.ReceiveMessages(messages);
return;
PUSH_MESSAGES_BACK:
// The messages could not be delivered => Put them back in the queue
await ReceiveMessages(messages);
return;
}
public async Task RegisterEndpoint(IEndPoint endPoint)
{
ASSERT((endPoint != null) && (!string.IsNullOrWhiteSpace(endPoint.ID)), $"Missing or invalid parameter '{nameof(endPoint)}'");
Action checkExisting = () =>
{
var existing = RegisteredEndpoints.TryGet(endPoint.ID); // nb: read-only => no need for "lock{}"
if (existing == null)
{
// OK
return;
}
// Not OK
throw new EndpointAlreadyRegistered($"The endpoint '{endPoint.ID}' has already been registered", existing);
};
checkExisting();
if (endPoint.IsOneShot)
{
// Check pending messages
var messages = await RestoreMessages(endPoint.ID);
if (messages != null)
{
ASSERT(messages.Count > 0, $"'{nameof(messages)}' is not supposed to be empty here");
await endPoint.ReceiveMessages(messages);
// nb: one-shot -> No need to register this endpoint ...
}
else // There's no pending messages
{
// Register endpoint
lock ( Locker )
{
checkExisting();
RegisteredEndpoints.Add(endPoint.ID, endPoint);
}
// Re-check pending messages (in case they've been added in the mean-time ...)
await CheckPendingMessages(endPoint.ID);
}
}
else // not endPoint.IsOneShot
{
// Register endpoint
lock ( Locker )
{
checkExisting();
RegisteredEndpoints.Add(endPoint.ID, endPoint);
}
// Re-check pending messages (in case they've been added in the mean-time ...)
await CheckPendingMessages(endPoint.ID);
}
}
public Task UnRegisterEndpoint(string id)
{
ASSERT(!string.IsNullOrWhiteSpace(id), $"Missing parameter '{nameof(id)}");
lock ( Locker )
{
var rc = RegisteredEndpoints.Remove(id);
ASSERT(rc, $"Could not unregister endpoint '{id}'"); // nb: can happen in case of race condition, but should be very rare
}
return(Task.FromResult(0));
}
public async Task ReceiveMessages(IEnumerable <TMessage> messages)
{
ASSERT(messages != null, $"Missing parameter '{nameof(messages)}'");
ASSERT(messages.Where(v => string.IsNullOrWhiteSpace(v.TryGetString(MessageKeys.KeyReceiverID))).Count() == 0, $"There are messages without '{MessageKeys.KeyReceiverID}' defined");
var messagesToSave = (new{ EndPointID = (string)null, Messages = (List <TMessage>)null }).NewAnonymousList();
var messagesToSend = (new{ EndPoint = (IEndPoint)null, Messages = (List <TMessage>)null }).NewAnonymousList();
var byEndPointIDs = messages.GroupBy(v => v.TryGetString(MessageKeys.KeyReceiverID)).ToDictionary(v => v.Key, v => v.ToList());
lock ( Locker )
{
foreach (var pair in byEndPointIDs)
{
var endPointID = pair.Key;
var msgs = pair.Value;
var endPoint = RegisteredEndpoints.TryGet(endPointID);
if (endPoint == null)
{
// These messages are for an endpoint that is not managed by me => Save them to Redis
messagesToSave.Add(new{ EndPointID = endPointID, Messages = msgs });
}
else if (endPoint.IsOneShot)
{
// These messages are for an endpoint that is managed by me but needs to be unregistered when it receives messages
var rc = RegisteredEndpoints.Remove(endPointID);
ASSERT(rc, $"Could not unregister endpoint '{endPointID}'");
messagesToSend.Add(new{ EndPoint = endPoint, Messages = msgs });
}
else
{
// These messages are for an endpoint that is managed by me
messagesToSend.Add(new{ EndPoint = endPoint, Messages = msgs });
}
}
}
var exception = (System.Exception)null; // The first exception encountered if any
foreach (var item in messagesToSend)
{
var notAwaited = Task.Run(async() => // nb: Run asynchroneously
{
try { await item.EndPoint.ReceiveMessages(item.Messages); }
catch (System.Exception ex) { exception = (exception ?? ex); }
});
}
foreach (var item in messagesToSave)
{
try { await SaveMessages(item.EndPointID, item.Messages); }
catch (System.Exception ex) { exception = (exception ?? ex); }
}
if (exception != null)
{
// An exception has been encountered => Rethrow the first one received
throw new ApplicationException($"An error occurred while receiving a message ({exception.GetType().FullName}): {exception.Message}", innerException: exception);
}
}