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minor improvement in glop presolve

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This commit is contained in:
Laurent Perron
2021-08-12 15:23:02 +02:00
parent ac76cb8f5e
commit 5496c87aa2
4 changed files with 15 additions and 6 deletions
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1
ortools/glop/BUILD
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@@ -326,6 +326,7 @@ cc_library(
":revised_simplex",
":status",
"//ortools/base",
"//ortools/base:iterator_adaptors",
"//ortools/lp_data",
"//ortools/lp_data:base",
"//ortools/lp_data:lp_data_utils",

2
ortools/glop/lp_solver.cc
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@@ -217,7 +217,7 @@ ProblemStatus LPSolver::SolveWithTimeLimit(const LinearProgram& lp,
RunRevisedSimplexIfNeeded(&solution, time_limit);
}
if (postsolve_is_needed) preprocessor.RecoverSolution(&solution);
if (postsolve_is_needed) preprocessor.DestructiveRecoverSolution(&solution);
const ProblemStatus status = LoadAndVerifySolution(lp, solution);
// LOG some statistics that can be parsed by our benchmark script.

8
ortools/glop/preprocessor.cc
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@@ -17,6 +17,7 @@
#include <limits>
#include "absl/strings/str_format.h"
#include "ortools/base/iterator_adaptors.h"
#include "ortools/base/strong_vector.h"
#include "ortools/glop/revised_simplex.h"
#include "ortools/glop/status.h"
@@ -177,6 +178,13 @@ void MainLpPreprocessor::RunAndPushIfRelevant(
}
void MainLpPreprocessor::RecoverSolution(ProblemSolution* solution) const {
SCOPED_INSTRUCTION_COUNT(time_limit_);
for (const auto& p : gtl::reversed_view(preprocessors_)) {
p->RecoverSolution(solution);
}
}
void MainLpPreprocessor::DestructiveRecoverSolution(ProblemSolution* solution) {
SCOPED_INSTRUCTION_COUNT(time_limit_);
while (!preprocessors_.empty()) {
preprocessors_.back()->RecoverSolution(solution);

10
ortools/glop/preprocessor.h
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@@ -110,6 +110,10 @@ class MainLpPreprocessor : public Preprocessor {
bool Run(LinearProgram* lp) final;
void RecoverSolution(ProblemSolution* solution) const override;
// Like RecoverSolution but destroys data structures as it goes to reduce peak
// RAM use. After calling this the MainLpPreprocessor object may no longer be
// used.
void DestructiveRecoverSolution(ProblemSolution* solution);
private:
// Runs the given preprocessor and push it on preprocessors_ for the postsolve
@@ -119,11 +123,7 @@ class MainLpPreprocessor : public Preprocessor {
LinearProgram* lp);
// Stack of preprocessors currently applied to the lp that needs postsolve.
//
// TODO(user): This is mutable so that the preprocessor can be freed as soon
// as their RecoverSolution() is called. Make RecoverSolution() non-const or
// remove this optimization?
mutable std::vector<std::unique_ptr<Preprocessor>> preprocessors_;
std::vector<std::unique_ptr<Preprocessor>> preprocessors_;
// Initial dimension of the lp given to Run(), for displaying purpose.
EntryIndex initial_num_entries_;