feat: Add support for problem changes (#34)

* feat: Add support for problem changes

- Since the methods in ProblemChangeDirector take
  interfaces, ProblemChange as a whole cannot be
  translated to pure Java (since that requires
  supporting casting an arbitary callable to any
  Java interface, which is not suported yet (nor
  planned to be supported)).

- Thus we goes for a more ugly approach: the
  ProblemChange runs in Python, and when a
  problem change director method is called,
  we compile/translate the supplied function
  to Java.

- We do a trick where we replace the Python
  working solution clone with the actual Java
  working solution in the closure before compiling
  the function so changes are applied to the right
  object. After the method is called, we then update
  the Python working solution from the java working
  solution so changes are reflected in it too.

- Users implement a ProblemChange by extending an
  abstract base class (which, among other things,
  raises an error if not all of its methods are
  implemented).

jpyinterpreter/src/main/python/conversions.py

@@ -117,7 +117,10 @@ def is_c_native(item):
             or module == '':  # if we cannot find module, assume it is not native
         return False
 
-    return is_native_module(importlib.import_module(module))
+    try:
+        return is_native_module(importlib.import_module(module))
+    except:
+        return True
 
 
 def init_type_to_compiled_java_class():

tests/test_solver_manager.py

@@ -26,7 +26,7 @@ class Value:
     @dataclass
     class Entity:
         code: Annotated[str, PlanningId]
-        value: Annotated[Value, PlanningVariable] = field(default=None)
+        value: Annotated[Value, PlanningVariable] = field(default=None, compare=False)
 
     @constraint_provider
     def my_constraints(constraint_factory: ConstraintFactory):
@@ -54,24 +54,22 @@ class Solution:
                               ValueRangeProvider]
         score: Annotated[SimpleScore, PlanningScore] = field(default=None)
 
-    # TODO: Support problem changes
-    # @Problem_change
-    # class UseOnlyEntityAndValueProblemChange:
-    #     def __init__(self, entity, value):
-    #         self.entity = entity
-    #         self.value = value
-    #
-    #     def doChange(self, solution: Solution, problem_change_director: timefold.solver.types.ProblemChangeDirector):
-    #         problem_facts_to_remove = solution.value_list.copy()
-    #         entities_to_remove = solution.entity_list.copy()
-    #         for problem_fact in problem_facts_to_remove:
-    #             problem_change_director.removeProblemFact(problem_fact,
-    #                                                       lambda value: solution.value_list.remove(problem_fact))
-    #         for removed_entity in entities_to_remove:
-    #             problem_change_director.removeEntity(removed_entity,
-    #                                                  lambda entity: solution.entity_list.remove(removed_entity))
-    #         problem_change_director.addEntity(self.entity, lambda entity: solution.entity_list.append(entity))
-    #         problem_change_director.addProblemFact(self.value, lambda value: solution.value_list.append(value))
+    class UseOnlyEntityAndValueProblemChange(ProblemChange[Solution]):
+        def __init__(self, entity, value):
+            self.entity = entity
+            self.value = value
+
+        def do_change(self, solution: Solution, problem_change_director: ProblemChangeDirector):
+            problem_facts_to_remove = solution.value_list.copy()
+            entities_to_remove = solution.entity_list.copy()
+            for problem_fact in problem_facts_to_remove:
+                problem_change_director.remove_problem_fact(problem_fact,
+                                                            lambda value: solution.value_list.remove(value))
+            for removed_entity in entities_to_remove:
+                problem_change_director.remove_entity(removed_entity,
+                                                      lambda entity: solution.entity_list.remove(entity))
+            problem_change_director.add_entity(self.entity, lambda entity: solution.entity_list.append(entity))
+            problem_change_director.add_problem_fact(self.value, lambda value: solution.value_list.append(value))
 
     solver_config = SolverConfig(
         solution_class=Solution,
@@ -97,27 +95,27 @@ def assert_solver_run(solver_manager, solver_job):
         assert 3 in value_list
         assert solver_manager.get_solver_status(1) == SolverStatus.NOT_SOLVING
 
-    # def assert_problem_change_solver_run(solver_manager, solver_job):
-    #     assert solver_manager.get_solver_status(1) != SolverStatus.NOT_SOLVING
-    #     solver_manager.addProblemChange(1, UseOnlyEntityAndValueProblemChange(Entity('D'), Value(6)))
-    #     lock.release()
-    #     solution = solver_job.get_final_best_solution()
-    #     assert solution.score.score() == 6
-    #     assert len(solution.entity_list) == 1
-    #     assert len(solution.value_range) == 1
-    #     assert solution.entity_list[0].code == 'D'
-    #     assert solution.entity_list[0].value.value == 6
-    #     assert solution.value_range[0].value == 6
-    #     assert solver_manager.get_solver_status(1) == SolverStatus.NOT_SOLVING
+    def assert_problem_change_solver_run(solver_manager, solver_job):
+        assert solver_manager.get_solver_status(1) != SolverStatus.NOT_SOLVING
+        solver_manager.add_problem_change(1, UseOnlyEntityAndValueProblemChange(Entity('D'), Value(6)))
+        lock.release()
+        solution = solver_job.get_final_best_solution()
+        assert solution.score.score() == 6
+        assert len(solution.entity_list) == 1
+        assert len(solution.value_list) == 1
+        assert solution.entity_list[0].code == 'D'
+        assert solution.entity_list[0].value.value == 6
+        assert solution.value_list[0].value == 6
+        assert solver_manager.get_solver_status(1) == SolverStatus.NOT_SOLVING
 
     with SolverManager.create(SolverFactory.create(solver_config)) as solver_manager:
         lock.acquire()
         solver_job = solver_manager.solve(1, problem)
         assert_solver_run(solver_manager, solver_job)
 
-        # lock.acquire()
-        # solver_job = solver_manager.solve(1, problem)
-        # assert_problem_change_solver_run(solver_manager, solver_job)
+        lock.acquire()
+        solver_job = solver_manager.solve(1, problem)
+        assert_problem_change_solver_run(solver_manager, solver_job)
 
         def get_problem(problem_id):
             assert problem_id == 1
@@ -129,9 +127,11 @@ def get_problem(problem_id):
                       .with_problem_finder(get_problem)).run()
         assert_solver_run(solver_manager, solver_job)
 
-        # lock.acquire()
-        #solver_job = solver_manager.solve(1, get_problem)
-        #assert_problem_change_solver_run(solver_manager, solver_job)
+        lock.acquire()
+        solver_job = (solver_manager.solve_builder()
+                      .with_problem_id(1)
+                      .with_problem_finder(get_problem)).run()
+        assert_problem_change_solver_run(solver_manager, solver_job)
 
         solution_list = []
         semaphore = Semaphore(0)
@@ -150,15 +150,16 @@ def on_best_solution_changed(solution):
         assert semaphore.acquire(timeout=1)
         assert len(solution_list) == 1
 
-        # solution_list = []
-        # lock.acquire()
-        # solver_job = (solver_manager.solve_builder()
-        #               .with_problem_id(1)
-        #               .with_problem_finder(get_problem)
-        #               .with_best_solution_consumer(on_best_solution_changed)
-        #               ).run()
-        #assert_problem_change_solver_run(solver_manager, solver_job)
-        # assert len(solution_list) == 1
+        solution_list = []
+        lock.acquire()
+        solver_job = (solver_manager.solve_builder()
+                      .with_problem_id(1)
+                      .with_problem_finder(get_problem)
+                      .with_best_solution_consumer(on_best_solution_changed)
+                      ).run()
+        assert_problem_change_solver_run(solver_manager, solver_job)
+        assert semaphore.acquire(timeout=1)
+        assert len(solution_list) == 1
 
         solution_list = []
         lock.acquire()
@@ -175,16 +176,20 @@ def on_best_solution_changed(solution):
         assert semaphore.acquire(timeout=1)
         assert len(solution_list) == 2
 
-        # solution_list = []
-        # lock.acquire()
-        # solver_job = (solver_manager.solve_builder()
-        #               .with_problem_id(1)
-        #               .with_problem_finder(get_problem)
-        #               .with_best_solution_consumer(on_best_solution_changed)
-        #               .with_final_best_solution_consumer(on_best_solution_changed)
-        #               ).run()
-        # assert_problem_change_solver_run(solver_manager, solver_job)
-        # assert len(solution_list) == 2
+        solution_list = []
+        lock.acquire()
+        solver_job = (solver_manager.solve_builder()
+                      .with_problem_id(1)
+                      .with_problem_finder(get_problem)
+                      .with_best_solution_consumer(on_best_solution_changed)
+                      .with_final_best_solution_consumer(on_best_solution_changed)
+                      ).run()
+        assert_problem_change_solver_run(solver_manager, solver_job)
+        # Wait for 2 acquires, one for best solution consumer,
+        # another for final best solution consumer
+        assert semaphore.acquire(timeout=1)
+        assert semaphore.acquire(timeout=1)
+        assert len(solution_list) == 2
 
 
 @pytest.mark.filterwarnings("ignore:.*Exception in thread.*:pytest.PytestUnhandledThreadExceptionWarning")

tests/test_solver_problem_change.py

@@ -0,0 +1,135 @@
+from timefold.solver.api import *
+from timefold.solver.annotation import *
+from timefold.solver.config import *
+from timefold.solver.constraint import *
+from timefold.solver.score import *
+
+from dataclasses import dataclass, field
+from typing import Annotated, List
+from threading import Thread
+
+
+@planning_entity
+@dataclass
+class Entity:
+    code: Annotated[str, PlanningId]
+    value: Annotated[int, PlanningVariable] = field(default=None, compare=False)
+
+
+@constraint_provider
+def maximize_constraints(constraint_factory: ConstraintFactory):
+    return [
+        constraint_factory.for_each(Entity)
+        .reward(SimpleScore.ONE, lambda entity: entity.value)
+        .as_constraint('Maximize value'),
+    ]
+
+
+@constraint_provider
+def minimize_constraints(constraint_factory: ConstraintFactory):
+    return [
+        constraint_factory.for_each(Entity)
+        .penalize(SimpleScore.ONE, lambda entity: entity.value)
+        .as_constraint('Minimize value'),
+    ]
+
+
+@planning_solution
+@dataclass
+class Solution:
+    entities: Annotated[List[Entity], PlanningEntityCollectionProperty]
+    value_range: Annotated[List[int], ValueRangeProvider]
+    score: Annotated[SimpleScore, PlanningScore] = field(default=None)
+
+    def __str__(self) -> str:
+        return str(self.entities)
+
+
+class AddEntity(ProblemChange[Solution]):
+    entity: Entity
+
+    def __init__(self, entity: Entity):
+        self.entity = entity
+
+    def do_change(self, working_solution: Solution, problem_change_director: ProblemChangeDirector):
+        problem_change_director.add_entity(self.entity,
+                                           lambda working_entity: working_solution.entities.append(working_entity))
+
+
+class RemoveEntity(ProblemChange[Solution]):
+    entity: Entity
+
+    def __init__(self, entity: Entity):
+        self.entity = entity
+
+    def do_change(self, working_solution: Solution, problem_change_director: ProblemChangeDirector):
+        problem_change_director.remove_entity(self.entity,
+                                              lambda working_entity: working_solution.entities.remove(working_entity))
+
+
+def test_add_entity():
+    solver_config = SolverConfig(
+        solution_class=Solution,
+        entity_class_list=[Entity],
+        score_director_factory_config=ScoreDirectorFactoryConfig(
+            constraint_provider_function=maximize_constraints,
+        ),
+        termination_config=TerminationConfig(
+            best_score_limit='6'
+        )
+    )
+
+    problem: Solution = Solution([Entity('A')], [1, 2, 3])
+    solver = SolverFactory.create(solver_config).build_solver()
+    result: Solution | None = None
+
+    def do_solve(problem: Solution):
+        nonlocal solver, result
+        result = solver.solve(problem)
+
+    thread = Thread(target=do_solve, args=(problem,), daemon=True)
+
+    thread.start()
+    solver.add_problem_change(AddEntity(Entity('B')))
+    thread.join(timeout=1)
+
+    if thread.is_alive():
+        raise AssertionError(f'Thread {thread} did not finish after 5 seconds')
+
+    assert result is not None
+    assert len(result.entities) == 2
+    assert result.score.score() == 6
+
+
+def test_remove_entity():
+    solver_config = SolverConfig(
+        solution_class=Solution,
+        entity_class_list=[Entity],
+        score_director_factory_config=ScoreDirectorFactoryConfig(
+            constraint_provider_function=minimize_constraints,
+        ),
+        termination_config=TerminationConfig(
+            best_score_limit='-1'
+        )
+    )
+
+    problem: Solution = Solution([Entity('A'), Entity('B')], [1, 2, 3])
+    solver = SolverFactory.create(solver_config).build_solver()
+    result: Solution | None = None
+
+    def do_solve(problem: Solution):
+        nonlocal solver, result
+        result = solver.solve(problem)
+
+    thread = Thread(target=do_solve, args=(problem,), daemon=True)
+
+    thread.start()
+    solver.add_problem_change(RemoveEntity(Entity('B')))
+    thread.join(timeout=1)
+
+    if thread.is_alive():
+        raise AssertionError(f'Thread {thread} did not finish after 5 seconds')
+
+    assert result is not None
+    assert len(result.entities) == 1
+    assert result.score.score() == -1

timefold-solver-python-core/src/main/python/api/__init__.py

@@ -1,3 +1,4 @@
+from .problem_change import *
 from .solver import *
 from .solver_factory import *
 from .solver_manager import *

timefold-solver-python-core/src/main/python/api/future.py

@@ -0,0 +1,42 @@
+from ..jpype_type_conversions import PythonBiFunction
+from typing import Awaitable, TypeVar, TYPE_CHECKING
+from asyncio import Future, get_event_loop, CancelledError
+
+if TYPE_CHECKING:
+    from java.util.concurrent import (Future as JavaFuture,
+                                      CompletableFuture as JavaCompletableFuture)
+
+
+Result = TypeVar('Result')
+
+
+def wrap_future(future: 'JavaFuture[Result]') -> Awaitable[Result]:
+    async def get_result() -> Result:
+        nonlocal future
+        return future.get()
+
+    return get_result()
+
+
+def wrap_completable_future(future: 'JavaCompletableFuture[Result]') -> Future[Result]:
+    loop = get_event_loop()
+    out = loop.create_future()
+
+    def result_handler(result, error):
+        nonlocal out
+        if error is not None:
+            out.set_exception(error)
+        else:
+            out.set_result(result)
+
+    def cancel_handler(python_future: Future):
+        nonlocal future
+        if isinstance(python_future.exception(), CancelledError):
+            future.cancel(True)
+
+    future.handle(PythonBiFunction(result_handler))
+    out.add_done_callback(cancel_handler)
+    return out
+
+
+__all__ = ['wrap_future', 'wrap_completable_future']