Add callbacks to pickup_vrp ortools solver #149
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- replace AddAtSolutionCallback by AddSearchMonitor
- make RoutingMonitor derive from SearchMonitor
- override/implement AtSolution, EnterSearch, ExitSearch
- plug user-defined callbacks into it
- stop search by raising a dedicated exception (returning False in
AtSolution does not work, because other SearchMonitor's created at
solver init according to searchparameters make the search continue
anyway)
- remove n_solutions from init_model() parameters: is was used for setting
searchParameters.number_of_solutions_to_collect but
- it causes segfault error when raising an exception in SearchMonitor
- it seems not being working as expected (no workingexample found with it)
see https://stackoverflow.com/questions/57424868/how-to-collect-more-than-one-solution-google-or-tools-tsp
that use a workaround to collect solutions
- add a test with ortools solver + callbacks
AtSolution() seems to be the simpler place to hook on_step() callback:
we can choose to stop there and the number of found solutions can
simulate a number of iterations.
- use solve() instead of solve_intern() - remove n_solutions - decrease time_limit in tests to accelerate them
This will replace previous `n_solutions` arg in `ORToolsGPDP`. See new test in tests/generic_tools/callbacks/test_ortools_with_callbacks.py.
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SearchMonitorobjectNB: the
on_step_end()is plugged here in theAtSolution()ortools hook. Which means an iteration for d-oCallbackcorresponds to finding a feasible solution for ortools routing solver.n_solutionsparameters frominit_solve()asn_solutionssolutions);NbIterationStoppercallback which will stops the optimization when a given number of iterations is reached.NB: when using it with
ORToolsGPDP, it will correspond to the number solutions found as we hooked inAtSolution(). So this will replace the previousn_solutionsparameters.