This allows a program to access execution statistics specific to
this solver. General statistics about CPU time and memory consumption
etc. is available from the built-in predicate
statistics/2.
For each of the possible keys Key, Value is unified
with the current value of a counter, which is simultaneously zeroed.
The following counters are maintained. See The Constraint System,
for details of what they all mean:
resumptions- The number of times a constraint was resumed.
entailments- The number of times a (dis)entailment was detected by a constraint.
prunings- The number of times a domain was pruned.
backtracks- The number of times a contradiction was found by a domain being wiped
out, or by a global constraint signalling failure. Other causes of
backtracking, such as failed Prolog tests, are not covered by this
counter.
constraints- The number of constraints created.