operations_research::sat::ObjectiveShavingSolver Class Reference

#include <shaving_solver.h>

Inheritance diagram for operations_research::sat::ObjectiveShavingSolver:

Public Member Functions
	ObjectiveShavingSolver (const SatParameters &local_parameters, NeighborhoodGeneratorHelper *helper, SharedClasses *shared)
	~ObjectiveShavingSolver () override
bool	TaskIsAvailable () override
std::function< void()>	GenerateTask (int64_t task_id) override
void	Synchronize () override
Public Member Functions inherited from operations_research::sat::SubSolver
	SubSolver (absl::string_view name, SubsolverType type)
virtual	~SubSolver ()=default
virtual bool	IsDone ()
double	deterministic_time () const
std::string	name () const
	Returns the name of this SubSolver. Used in logs.
SubsolverType	type () const
	Returns the type of the subsolver.
void	AddTaskDuration (double duration_in_seconds)
void	AddTaskDeterministicDuration (double deterministic_duration)
std::string	TimingInfo () const
std::string	DeterministicTimingInfo () const

Additional Inherited Members
Public Types inherited from operations_research::sat::SubSolver
enum	SubsolverType { FULL_PROBLEM , FIRST_SOLUTION , INCOMPLETE , HELPER }

Detailed Description

Definition at line 38 of file shaving_solver.h.

Constructor & Destructor Documentation

ObjectiveShavingSolver()

operations_research::sat::ObjectiveShavingSolver::ObjectiveShavingSolver	(	const SatParameters &	local_parameters,
		NeighborhoodGeneratorHelper *	helper,
		SharedClasses *	shared )

Definition at line 47 of file shaving_solver.cc.

~ObjectiveShavingSolver()

operations_research::sat::ObjectiveShavingSolver::~ObjectiveShavingSolver ( )

override

Definition at line 56 of file shaving_solver.cc.

Member Function Documentation

GenerateTask()

std::function< void()> operations_research::sat::ObjectiveShavingSolver::GenerateTask ( int64_t task_id )

overridevirtual

Returns a task to run. The task_id is just an ever increasing counter that correspond to the number of total calls to GenerateTask().

Todo

(user): We could use a more complex selection logic and pass in the deterministic time limit this subtask should run for. Unclear at this stage.

This is only called by the main thread.

Implements operations_research::sat::SubSolver.

Definition at line 68 of file shaving_solver.cc.

Synchronize()

void operations_research::sat::ObjectiveShavingSolver::Synchronize ( )

overridevirtual

Synchronizes with the external world from this SubSolver point of view. Also incorporate the results of the latest completed tasks if any.

Note(user): The intended implementation for determinism is that tasks update asynchronously (and so non-deterministically) global "shared" classes, but this global state is incorporated by the Subsolver only when Synchronize() is called.

This is only called by the main thread in Subsolver creation order.

We are just waiting for the inner code to check the time limit or to return nicely.

Todo

(user): Also stop if we have enough newly fixed / improved root level bounds so that we think it is worth represolving and restarting.

The current objective lower bound has been improved, restarting.

A solution has been found that is better than the current target objective upper bound. Restarting to use a smaller delta.

If the range has been reduced enough to warrant a delta of 1, while the current search uses a delta > 1. Restarting to switch to the delta of 1.

Implements operations_research::sat::SubSolver.

Definition at line 111 of file shaving_solver.cc.

TaskIsAvailable()

bool operations_research::sat::ObjectiveShavingSolver::TaskIsAvailable ( )

overridevirtual

Returns true iff GenerateTask() can be called. This is only called by the main thread in a sequential fashion.

We only support one task at the time.

Implements operations_research::sat::SubSolver.

Definition at line 60 of file shaving_solver.cc.

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The documentation for this class was generated from the following files:

• ortools/sat/shaving_solver.h
• ortools/sat/shaving_solver.cc