Accessing solver from BestBoundCallback in CP-SAT

[Patrik Mandelin]

Hi,

I am trying to do a more advanced monitoring of relative gap in the solver, to terminate when the gap is small and we have a slow evolution of the gap.

Doing so in a CpSolverSolutionCallback works just fine, since we have full access to the solver parameters.

However, since I have more frequent updates of bound, i wish to implement the same logic in the bound callback.

This is where I have problems trying to access the `solver.objectiveValue()`.

A reference to 'solver' has been passed to the class managing the callback (which is a plain Consumer<Double> in java), but calling objectiveValue() generates error:
`Cannot invoke "com.google.ortools.sat.CpSolverResponse.getObjectiveValue()" because "this.solveResponse" is null`.

I am sure the solution is obvious to many of you, but I have had some frustrating days trying to progress this - any hints are highly appreciated.

Is there a way to access the objective from a bounds callback?

Cheers,

Patrik

[Laurent Perron]

No. You need to store it on your side. 

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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[Patrik Mandelin]

Thank you - that is easily done.
But what about 'wall time' - then I presume this is not readily available in a bounds callback either?

Cheers,

Patrik

[Laurent Perron]

No, but you can use your own timer. 

--Laurent

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