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fix 2 sat bugs

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This commit is contained in:
Laurent Perron
2020-11-25 22:38:26 +01:00
parent 9105f053ac
commit b7d2104898
8 changed files with 79 additions and 59 deletions
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44
ortools/sat/timetable.cc
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@@ -68,22 +68,25 @@ void TimeTablingPerTask::RegisterWith(GenericLiteralWatcher* watcher) {
watcher->RegisterReversibleInt(id, &forward_num_tasks_to_sweep_);
watcher->RegisterReversibleInt(id, &backward_num_tasks_to_sweep_);
watcher->RegisterReversibleInt(id, &num_profile_tasks_);
// Changing the times or pushing task absence migth have side effects on the
// other intervals, so we would need to be called again in this case.
watcher->NotifyThatPropagatorMayNotReachFixedPointInOnePass(id);
}
// Note that we relly on being called again to reach a fixed point.
bool TimeTablingPerTask::Propagate() {
// Repeat until the propagator does not filter anymore.
profile_changed_ = true;
while (profile_changed_) {
profile_changed_ = false;
// This can fail if the profile exceeds the resource capacity.
if (!BuildProfile()) return false;
// Update the minimum start times.
if (!SweepAllTasks(/*is_forward=*/true)) return false;
// We reuse the same profile, but reversed, to update the maximum end times.
ReverseProfile();
// Update the maximum end times (reversed problem).
if (!SweepAllTasks(/*is_forward=*/false)) return false;
}
// This can fail if the profile exceeds the resource capacity.
if (!BuildProfile()) return false;
// Update the minimum start times.
if (!SweepAllTasks(/*is_forward=*/true)) return false;
// We reuse the same profile, but reversed, to update the maximum end times.
ReverseProfile();
// Update the maximum end times (reversed problem).
if (!SweepAllTasks(/*is_forward=*/false)) return false;
return true;
}
@@ -307,21 +310,6 @@ bool TimeTablingPerTask::SweepTask(int task_id) {
return false;
}
// The profile needs to be recomputed if we pushed something (because it can
// have side effects). Note that for the case where the interval is optional
// but not its start, it is possible that UpdateStartingTime() didn't change
// the start, so we need to test this in order to avoid an infinite loop.
//
// TODO(user): find an efficient way to keep the start_max < new_end_min
// condition. The problem is that ReduceProfile() assumes that by_end_min and
// by_start_max are up to date (this is not necessarily the case if we use
// the old condition). A solution is to update those vector before calling
// ReduceProfile() or to ReduceProfile() directly after BuildProfile() in the
// main loop.
if (helper_->StartMin(task_id) != initial_start_min) {
profile_changed_ = true;
}
return true;
}