Hi all,

I'm working on a Drools Planner 5.4.0.CR1 implementation for a scheduling app.

First, some background:

The solution class is 'Schedule' and the PlanningEntity is 'Meeting'. Meetings consist of timeslots (or 'slots'), and two participants in complimentary roles 'planners' and 'suppliers'. Since there are more planners than suppliers, I've structured the Schedule model so that its meeting collection is basically the cross-product of slots and planners. Suppliers are configured as the @PlanningVariable in a meeting. The meeting list in the schedule is also annotated as a @PlanningEntityCollectionProperty. I've structured three MoveFactories that add, subtract or swap suppliers from meeting to meeting.

That part works fairly well, however, when I try to try to run my solution through a Solver, I am inevitably plagued with a dreaded message like this:

	java.lang.IllegalArgumentException: The entity (Meeting[slot: 26, planner: 29C2E0FF-00EE-409F-B05B-B175B30A6B45, supplier: BB25B297-54FA-45BD-923A-C209848E74B4,
	hashCode: 1219749520, solutionHashCode: -1086095971, slotHashCode: 436282962, plannerHashCode: -2037841459]) was never added to this ScoreDirector.
		at org.drools.planner.core.score.director.drools.DroolsScoreDirector.afterAllVariablesChanged(DroolsScoreDirector.java:110)
		at org.drools.planner.core.score.director.drools.DroolsScoreDirector.afterVariableChanged(DroolsScoreDirector.java:120)
		at com.somecompany.scheduler.moves.AddSupplierToMeetingMove.doMove(AddSupplierToMeetingMove.groovy:36)
		at org.drools.planner.core.localsearch.decider.DefaultDecider.doMove(DefaultDecider.java:128)
		at org.drools.planner.core.localsearch.decider.DefaultDecider.decideNextStep(DefaultDecider.java:103)
		at org.drools.planner.core.localsearch.DefaultLocalSearchSolverPhase.solve(DefaultLocalSearchSolverPhase.java:57)
		at org.drools.planner.core.solver.DefaultSolver.runSolverPhases(DefaultSolver.java:183)
		at org.drools.planner.core.solver.DefaultSolver.solve(DefaultSolver.java:151)
		at org.spockframework.util.GroovyRuntimeUtil.invokeMethod(GroovyRuntimeUtil.java:100)
		at com.somecompany.scheduler.solver.SolverSpec.should solve schedule(SolverSpec.groovy:59)

It seems to happen randomly, with different entities each time, but I've not yet had a successful run of a full solve cycle without hitting it a least once. Unfortunately, it kills my whole process.

I've step debugged through the planner internals and verified that all the meetings are getting added to the working memory, including the offending one:

	2012-05-04 16:30:17,379 INFO  com.somecompany.scheduler.solver.SolverSpec  - Meeting[slot: 26, planner: 29C2E0FF-00EE-409F-B05B-B175B30A6B45, supplier:
	FEA76C13-C9E2-42EC-977C-BCBB0BD1FFA0, hashCode: 1219749520, solutionHashCode: -574491332, slotHashCode: 436282962, plannerHashCode: -2037841459]

I was pretty certain my issue has to do with the meeting's hashCode value, but as you'll see they're exactly the same in working memory as they are when . I'm using commons HashCodeBuilder and EqualsBuilder to check only the fixed slot and planner values. The solutionHashCode changes based on the slot, planner and supplier-- supplier being the @PlanningVariable. I've pasted the full log, with trace enabled, here for review:

The error is listed at 2012-05-04 16:30:37,168.

The original meeting in working memory is listed at 2012-05-04 16:30:17,379 (toward the middle of entries with that timestamp).

I couldn't find an easy way to add a knowledge session logger in planner, but that might also be useful.