Source/JavaScriptCore/heap/MarkingConstraint.h

/*
 * Copyright (C) 2017 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
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#pragma once

#include "ConstraintVolatility.h"
#include "VisitingTimeout.h"
#include <limits.h>
#include <wtf/FastMalloc.h>
#include <wtf/Function.h>
#include <wtf/MonotonicTime.h>
#include <wtf/Noncopyable.h>
#include <wtf/text/CString.h>

namespace JSC {

class MarkingConstraintSet;
class SlotVisitor;

class MarkingConstraint {
    WTF_MAKE_NONCOPYABLE(MarkingConstraint);
    WTF_MAKE_FAST_ALLOCATED;
public:
    JS_EXPORT_PRIVATE MarkingConstraint(
        CString abbreviatedName, CString name,
        ::Function<void(SlotVisitor&, const VisitingTimeout&)>,
        ConstraintVolatility);
    
    JS_EXPORT_PRIVATE MarkingConstraint(
        CString abbreviatedName, CString name,
        ::Function<void(SlotVisitor&, const VisitingTimeout&)>,
        ::Function<double(SlotVisitor&)>,
        ConstraintVolatility);
    
    JS_EXPORT_PRIVATE ~MarkingConstraint();
    
    unsigned index() const { return m_index; }
    
    const char* abbreviatedName() const { return m_abbreviatedName.data(); }
    const char* name() const { return m_name.data(); }
    
    void resetStats();
    
    size_t lastVisitCount() const { return m_lastVisitCount; }
    
    void execute(SlotVisitor&, bool& didVisitSomething, MonotonicTime timeout);
    
    double quickWorkEstimate(SlotVisitor& visitor)
    {
        if (!m_quickWorkEstimateFunction)
            return 0;
        return m_quickWorkEstimateFunction(visitor);
    }
    
    double workEstimate(SlotVisitor& visitor)
    {
        return lastVisitCount() + quickWorkEstimate(visitor);
    }
    
    ConstraintVolatility volatility() const { return m_volatility; }
    
private:
    friend class MarkingConstraintSet; // So it can set m_index.
    
    unsigned m_index { UINT_MAX };
    CString m_abbreviatedName;
    CString m_name;
    ::Function<void(SlotVisitor&, const VisitingTimeout& timeout)> m_executeFunction;
    ::Function<double(SlotVisitor&)> m_quickWorkEstimateFunction;
    ConstraintVolatility m_volatility;
    size_t m_lastVisitCount { 0 };
};

} // namespace JSC