[certi-dev] NextEventRequestAvailable and LBTS - Possible deadlock?

[Ijperen, Jeroen van]

Hello,

Currently I am having some difficulties getting my time constrained federates 
to work with Certi. Each federate uses "NextEventRequestAvailable" to advance 
their time, but none receive a TimeAdvanceGrant...

My federation starts as follows:
1. Federate A starts, joins and becomes time constrained and time regulating
2. Federate A does a NERA (NextEventRequestAvailable) for time 1.0
3. Federate A received a TAG (TimeAdvanceGrant) callback for time 1.0
4. Federate B starts, joins and becomes time constrained
5. Federate B does a NERA for time 1.0
6. Federate B received a TAG callback for time 1.0
7. Federate A does a NERA for time 2.0 and waits for a TAG...
8. Federate B does a NERA for time 2.0 and waits for a TAG...

Internally I see that at point 7 Federate A compares its requested time (2.0) 
to the LBTS, which is 1.0 (the time Federate B was granted at 6). Since its 
request is higher than the LBTS it keeps waiting. At point 8 Federate B 
compares its requested time (also 2.0) to the LBTS, which is 1.0 (the time 
Federate A was granted at 3).

At this point in time both Federates are deadlocked as far as NERA is concerned.

Can you reproduce this sequence of events, and how can we fix this?

>From what I understood from the standard, is that a NERA can get a TAG 
>response with a lower time than requested, at the moment it receives TSO 
>messages for that lower time. I do not see this behavior in CERTI... I think 
>it is required, so that the LBTS can be updated with the requested times, as 
>long as no TSO messages need to be delivered for earlier times.

Kind regards,

Jeroen v. IJperen
TASK24