operations_research::math_opt::UpdateTracker Class Reference

#include <update_tracker.h>

Public Member Functions
	UpdateTracker (const std::shared_ptr< ModelStorage > &storage)
	~UpdateTracker ()
absl::StatusOr< std::optional< ModelUpdateProto > >	ExportModelUpdate (bool remove_names=false)
absl::Status	AdvanceCheckpoint ()
absl::StatusOr< ModelProto >	ExportModel (bool remove_names=false) const

Detailed Description

Tracks the changes of the model.

This is an advanced feature that most users won't need. It is used internally to implement incrementalism but users don't have to understand how it works to use incremental solve.

For each update tracker we define a checkpoint that is the starting point used to compute the ModelUpdateProto.

No member function should be called after the destruction of the Model object. Note though that it is safe to call the destructor of UpdateTracker even if the Model object has been destroyed already.

Thread-safety: UpdateTracker methods must not be used while modifying the model (variables, constraints, ...). The user is expected to use proper synchronization primitives to serialize changes to the model and the use of the update trackers. The methods of different instances of UpdateTracker are safe to be called concurrently (i.e. multiple trackers can be called concurrently on ExportModelUpdate() or AdvanceCheckpoint()). The destructor of UpdateTracker is thread-safe.

Example: Model model; ... const std::unique_ptr<UpdateTracker> update_tracker = model.NewUpdateTracker();

model.AddVariable(0.0, 1.0, true, "y"); model.set_maximize(true);

ASSIGN_OR_RETURN(const std::optional<ModelUpdateProto> update_proto, update_tracker.ExportModelUpdate()); RETURN_IF_ERROR(update_tracker.AdvanceCheckpoint());

if (update_proto) { ... use *update_proto here ... }

Definition at line 70 of file update_tracker.h.

Constructor & Destructor Documentation

UpdateTracker()

operations_research::math_opt::UpdateTracker::UpdateTracker ( const std::shared_ptr< ModelStorage > & storage )

explicit

This constructor should not be used directly. Instead use Model::NewUpdateTracker().

Definition at line 38 of file update_tracker.cc.

~UpdateTracker()

operations_research::math_opt::UpdateTracker::~UpdateTracker

(

)

If the model has already been destroyed, the update tracker has been automatically cleaned.

Definition at line 28 of file update_tracker.cc.

Member Function Documentation

AdvanceCheckpoint()

absl::Status operations_research::math_opt::UpdateTracker::AdvanceCheckpoint

(

)

Uses the current model state as the starting point to calculate the ModelUpdateProto next time ExportModelUpdate() is called.

If fails if the Model has been destroyed.

Definition at line 51 of file update_tracker.cc.

ExportModel()

absl::StatusOr< ModelProto > operations_research::math_opt::UpdateTracker::ExportModel

(

bool

remove_names = false

)

const

Returns a proto representation of the whole model.

This is a shortcut method that is equivalent to calling Model::ExportModel(). It is there so that users of the UpdateTracker can avoid having to keep a reference to the Model model.

If fails if the Model has been destroyed.

Definition at line 60 of file update_tracker.cc.

ExportModelUpdate()

absl::StatusOr< std::optional< ModelUpdateProto > > operations_research::math_opt::UpdateTracker::ExportModelUpdate

(

bool

remove_names = false

)

Returns a proto representation of the changes to the model since the most recent checkpoint (i.e. last time AdvanceCheckpoint() was called); nullopt if the update would have been empty.

If fails if the Model has been destroyed.

Definition at line 43 of file update_tracker.cc.

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

• ortools/math_opt/cpp/update_tracker.h
• ortools/math_opt/cpp/update_tracker.cc