private async Task<bool> Invoke(MessageResult result, Action<Subscription, object> beforeInvoke, object state)
{
// Change the state from idle to invoking callback
var prevState = Interlocked.CompareExchange(ref _subscriptionState,
SubscriptionState.InvokingCallback,
SubscriptionState.Idle);
if (prevState == SubscriptionState.Disposed)
{
// Only allow terminal messages after dispose
if (!result.Terminal)
{
return false;
}
}
beforeInvoke(this, state);
_counters.MessageBusMessagesReceivedTotal.IncrementBy(result.TotalCount);
_counters.MessageBusMessagesReceivedPerSec.IncrementBy(result.TotalCount);
try
{
return await _callback(result, _callbackState);
}
finally
{
// Go from invoking callback to idle
Interlocked.CompareExchange(ref _subscriptionState,
SubscriptionState.Idle,
SubscriptionState.InvokingCallback);
}
}
private Task<bool> TriggerAcks(MessageResult result, object state)
{
result.Messages.Enumerate<object>(m => m.IsAck,
(s, m) => ((IAckHandler)s).TriggerAck(m.CommandId),
state: _ackHandler);
return TaskAsyncHelper.True;
}
public virtual Task<bool> Invoke(MessageResult result)
{
return Invoke(result, (s, o) => { }, state: null);
}
public async Task Work()
{
// Set the state to working
Interlocked.Exchange(ref _state, State.Working);
var items = new List<ArraySegment<Message>>();
while (Alive)
{
int totalCount;
object state;
items.Clear();
PerformWork(items, out totalCount, out state);
if (items.Count > 0)
{
var messageResult = new MessageResult(items, totalCount);
bool result = await Invoke(messageResult, (s, o) => s.BeforeInvoke(o), state);
if (!result)
{
Dispose();
// If the callback said it's done then stop
break;
}
}
else
{
break;
}
}
}