public IEnumerable <Action <IConsumeContext <TMessage> > > GetSaga <TMessage>(IConsumeContext <TMessage> context, Guid sagaId,
InstanceHandlerSelector <TSaga, TMessage>
selector, ISagaPolicy <TSaga, TMessage> policy)
where TMessage : class
{
bool needToLeaveSagas = true;
Monitor.Enter(_sagas);
try
{
TSaga instance = _sagas[sagaId];
if (instance == null)
{
if (policy.CanCreateInstance(context))
{
instance = policy.CreateInstance(context, sagaId);
_sagas.Add(instance);
lock (instance)
{
Monitor.Exit(_sagas);
needToLeaveSagas = false;
yield return(x =>
{
if (_log.IsDebugEnabled)
{
_log.DebugFormat("SAGA: {0} Creating New {1} for {2}", typeof(TSaga).ToFriendlyName(), sagaId,
typeof(TMessage).ToFriendlyName());
}
try
{
foreach (var callback in selector(instance, x))
{
callback(x);
}
if (policy.CanRemoveInstance(instance))
{
_sagas.Remove(instance);
}
}
catch (Exception ex)
{
var sex = new SagaException("Create Saga Instance Exception", typeof(TSaga), typeof(TMessage), sagaId, ex);
if (_log.IsErrorEnabled)
{
_log.Error(sex);
}
throw sex;
}
});
}
}
else
{
if (_log.IsDebugEnabled)
{
_log.DebugFormat("SAGA: {0} Ignoring Missing {1} for {2}", typeof(TSaga).ToFriendlyName(), sagaId,
typeof(TMessage).ToFriendlyName());
}
}
}
else
{
if (policy.CanUseExistingInstance(context))
{
Monitor.Exit(_sagas);
needToLeaveSagas = false;
lock (instance)
{
yield return(x =>
{
if (_log.IsDebugEnabled)
{
_log.DebugFormat("SAGA: {0} Using Existing {1} for {2}", typeof(TSaga).ToFriendlyName(), sagaId,
typeof(TMessage).ToFriendlyName());
}
try
{
foreach (var callback in selector(instance, x))
{
callback(x);
}
if (policy.CanRemoveInstance(instance))
{
_sagas.Remove(instance);
}
}
catch (Exception ex)
{
var sex = new SagaException("Existing Saga Instance Exception", typeof(TSaga), typeof(TMessage), sagaId, ex);
if (_log.IsErrorEnabled)
{
_log.Error(sex);
}
throw sex;
}
});
}
}
else
{
if (_log.IsDebugEnabled)
{
_log.DebugFormat("SAGA: {0} Ignoring Existing {1} for {2}", typeof(TSaga).ToFriendlyName(), sagaId,
typeof(TMessage).ToFriendlyName());
}
}
}
}
finally
{
if (needToLeaveSagas)
{
Monitor.Exit(_sagas);
}
}
}