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[CP-SAT] limit effort in feasibility_jump; new experimental scheduling search on cumulative

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This commit is contained in:
Laurent Perron
2023-10-29 15:31:06 +01:00
parent 79bd14424f
commit 185b77cea0
12 changed files with 129 additions and 63 deletions
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58
ortools/sat/integer_search.cc
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@@ -679,7 +679,8 @@ std::function<BooleanOrIntegerLiteral()> CumulativePrecedenceSearchHeuristic(
auto* repo = model->GetOrCreate<IntervalsRepository>();
auto* integer_trail = model->GetOrCreate<IntegerTrail>();
auto* trail = model->GetOrCreate<Trail>();
return [repo, integer_trail, trail]() {
auto* search_helper = model->GetOrCreate<IntegerSearchHelper>();
return [repo, integer_trail, trail, search_helper]() {
SchedulingConstraintHelper* best_helper = nullptr;
int best_before = 0;
int best_after = 0;
@@ -715,6 +716,7 @@ std::function<BooleanOrIntegerLiteral()> CumulativePrecedenceSearchHeuristic(
// Set their demand to zero.
while (next_end < num_tasks && by_emin[next_end].time == time) {
const int t = by_emin[next_end].task_index;
if (!helper->IsPresent(t)) continue;
if (added_demand[t] > 0) {
current_height -= added_demand[t];
added_demand[t] = 0;
@@ -730,6 +732,7 @@ std::function<BooleanOrIntegerLiteral()> CumulativePrecedenceSearchHeuristic(
// TODO(user): tie-break tasks not fitting in the profile smartly.
while (next_start < num_tasks && by_smin[next_start].time == time) {
const int t = by_smin[next_start].task_index;
if (!helper->IsPresent(t)) continue;
if (added_demand[t] == -1) continue; // Corner case.
const IntegerValue demand_min = h.demand_helper->DemandMin(t);
if (current_height + demand_min <= capacity_max) {
@@ -763,6 +766,9 @@ std::function<BooleanOrIntegerLiteral()> CumulativePrecedenceSearchHeuristic(
}
open_tasks.push_back(first_skipped_task);
// TODO(user): If the two box cannot overlap because of high demand, use
// repo.CreateDisjunctivePrecedenceLiteral() instead.
//
// TODO(user): Add heuristic ordering for creating interesting precedence
// first.
bool found_precedence_to_add = false;
@@ -817,10 +823,29 @@ std::function<BooleanOrIntegerLiteral()> CumulativePrecedenceSearchHeuristic(
//
// TODO(user): We need to add the reason for demand_min and capacity_max.
// TODO(user): unfortunately we can't report it from here.
std::vector<IntegerLiteral> integer_reason;
if (!h.capacity.IsConstant()) {
integer_reason.push_back(
integer_trail->UpperBoundAsLiteral(h.capacity));
}
const auto& demands = h.demand_helper->Demands();
for (const int t : open_tasks) {
if (helper->IsOptional(t)) {
CHECK(trail->Assignment().LiteralIsTrue(helper->PresenceLiteral(t)));
conflict.push_back(helper->PresenceLiteral(t).Negated());
}
const AffineExpression d = demands[t];
if (!d.IsConstant()) {
integer_reason.push_back(integer_trail->LowerBoundAsLiteral(d));
}
}
integer_trail->ReportConflict(conflict, integer_reason);
search_helper->NotifyThatConflictWasFoundDuringGetDecision();
if (VLOG_IS_ON(2)) {
LOG(INFO) << "Conflict between precedences !";
for (const int t : open_tasks) LOG(INFO) << helper->TaskDebugString(t);
}
return BooleanOrIntegerLiteral();
}
// TODO(user): add heuristic criteria, right now we stop at first
@@ -1252,9 +1277,9 @@ bool IntegerSearchHelper::BeforeTakingDecision() {
return true;
}
LiteralIndex IntegerSearchHelper::GetDecision(
const std::function<BooleanOrIntegerLiteral()>& f) {
LiteralIndex decision = kNoLiteralIndex;
bool IntegerSearchHelper::GetDecision(
const std::function<BooleanOrIntegerLiteral()>& f, LiteralIndex* decision) {
*decision = kNoLiteralIndex;
while (!time_limit_->LimitReached()) {
BooleanOrIntegerLiteral new_decision;
if (integer_trail_->InPropagationLoop()) {
@@ -1267,6 +1292,12 @@ LiteralIndex IntegerSearchHelper::GetDecision(
}
if (!new_decision.HasValue()) {
new_decision = f();
if (must_process_conflict_) {
must_process_conflict_ = false;
sat_solver_->ProcessCurrentConflict();
(void)sat_solver_->FinishPropagation();
return false;
}
}
if (!new_decision.HasValue() &&
integer_trail_->CurrentBranchHadAnIncompletePropagation()) {
@@ -1283,13 +1314,13 @@ LiteralIndex IntegerSearchHelper::GetDecision(
// until we have a conflict with these decisions, but it is currently
// hard to do so.
if (new_decision.boolean_literal_index != kNoLiteralIndex) {
decision = new_decision.boolean_literal_index;
*decision = new_decision.boolean_literal_index;
} else {
decision =
*decision =
encoder_->GetOrCreateAssociatedLiteral(new_decision.integer_literal)
.Index();
}
if (sat_solver_->Assignment().LiteralIsAssigned(Literal(decision))) {
if (sat_solver_->Assignment().LiteralIsAssigned(Literal(*decision))) {
// TODO(user): It would be nicer if this can never happen. For now, it
// does because of the Propagate() not reaching the fixed point as
// mentioned in a TODO above. As a work-around, we display a message
@@ -1300,7 +1331,7 @@ LiteralIndex IntegerSearchHelper::GetDecision(
}
break;
}
return decision;
return true;
}
bool IntegerSearchHelper::TakeDecision(Literal decision) {
@@ -1382,17 +1413,22 @@ SatSolver::Status IntegerSearchHelper::SolveIntegerProblem() {
LiteralIndex decision = kNoLiteralIndex;
while (true) {
if (sat_solver_->ModelIsUnsat()) return sat_solver_->UnsatStatus();
if (heuristics.next_decision_override != nullptr) {
// Note that to properly count the num_times, we do not want to move
// this function, but actually call that copy.
decision = GetDecision(heuristics.next_decision_override);
if (!GetDecision(heuristics.next_decision_override, &decision)) {
continue;
}
if (decision == kNoLiteralIndex) {
heuristics.next_decision_override = nullptr;
}
}
if (decision == kNoLiteralIndex) {
decision =
GetDecision(heuristics.decision_policies[heuristics.policy_index]);
if (!GetDecision(heuristics.decision_policies[heuristics.policy_index],
&decision)) {
continue;
}
}
// Probing?