RulesEngine and guard relaxation interaction

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The sequence of events is something like this:

-Guard condition becomes true
-Rule fires, creating token A
-Solver decides A
-More planning happens, in which a resource token B is created and,
separately, a path between the temporal variable of B and some variable in
the guard that created A is created in the constraint network.
-The Solver executes a threat decision point, placing a temporal constraint
on B.
-The Solver un-does the decision point, deleting the constraint.
-The constraint engine then calls relax() on every variable reachable from
B's temporal variable, one of which is in the guard that created A
-When the guard is relaxed, the condition is no longer simply true, so the
rule is undone, which causes A to get deleted while it's still on the
decision stack.

There are two components to a fix:
1) specified variables maybe shouldn't pass on relaxation messages when
they have no effect (poss. true for all variables?)
2) rules should only fire/un-fire after propagation is complete, then cause
re-propagation.

Original issue reported on code.google.com by miata...@gmail.com on 20 May 2010 at 4:47

[GoogleCodeExporter]

Fixed in r6032 by adding post-propagation callbacks to the ConstraintEngine 
which are invoked after propagation is complete but before the message that 
propagation is complete has been issued, potentially causing more propagation.

Original comment by miata...@gmail.com on 8 Jun 2010 at 4:26

• Changed state: Fixed