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/*
* Copyright (C) 2017-2021 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "VisitCounter.h"
#include <wtf/BitVector.h>
#include <wtf/Condition.h>
#include <wtf/Deque.h>
#include <wtf/FastMalloc.h>
#include <wtf/Lock.h>
#include <wtf/Noncopyable.h>
#include <wtf/ScopedLambda.h>
#include <wtf/Vector.h>
namespace JSC {
class Heap;
class MarkingConstraint;
class MarkingConstraintSet;
class MarkingConstraintSolver {
WTF_MAKE_NONCOPYABLE(MarkingConstraintSolver);
WTF_MAKE_FAST_ALLOCATED;
public:
MarkingConstraintSolver(MarkingConstraintSet&);
~MarkingConstraintSolver();
bool didVisitSomething() const;
enum SchedulerPreference {
ParallelWorkFirst,
NextConstraintFirst
};
void execute(SchedulerPreference, ScopedLambda<std::optional<unsigned>()> pickNext);
void drain(BitVector& unexecuted);
void converge(const Vector<MarkingConstraint*>& order);
void execute(MarkingConstraint&);
// Parallel constraints can add parallel tasks.
void addParallelTask(RefPtr<SharedTask<void(SlotVisitor&)>>, MarkingConstraint&);
private:
void runExecutionThread(SlotVisitor&, SchedulerPreference, ScopedLambda<std::optional<unsigned>()> pickNext);
struct TaskWithConstraint {
TaskWithConstraint() { }
TaskWithConstraint(RefPtr<SharedTask<void(SlotVisitor&)>> task, MarkingConstraint* constraint)
: task(WTFMove(task))
, constraint(constraint)
{
}
bool operator==(const TaskWithConstraint& other) const
{
return task == other.task
&& constraint == other.constraint;
}
RefPtr<SharedTask<void(SlotVisitor&)>> task;
MarkingConstraint* constraint { nullptr };
};
Heap& m_heap;
SlotVisitor& m_mainVisitor;
MarkingConstraintSet& m_set;
BitVector m_executed;
Deque<TaskWithConstraint, 32> m_toExecuteInParallel;
Vector<unsigned, 32> m_toExecuteSequentially;
Lock m_lock;
Condition m_condition;
bool m_pickNextIsStillActive { true };
unsigned m_numThreadsThatMayProduceWork { 0 };
Vector<VisitCounter, 16> m_visitCounters;
};
} // namespace JSC