Source/JavaScriptCore/heap/MutatorScheduler.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
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 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#pragma once

#include <wtf/FastMalloc.h>
#include <wtf/MonotonicTime.h>
#include <wtf/Noncopyable.h>

namespace JSC {

class MutatorScheduler {
    WTF_MAKE_NONCOPYABLE(MutatorScheduler);
    WTF_MAKE_FAST_ALLOCATED;
public:
    enum State {
        Normal, // Not collecting.
        Stopped,
        Resumed
    };
    
    MutatorScheduler();
    virtual ~MutatorScheduler();
    
    virtual State state() const = 0;
    
    virtual void beginCollection() = 0;
    
    virtual void didStop();
    virtual void willResume();
    
    // At the top of an iteration, the GC will may call didReachTermination.
    virtual void didReachTermination();
    
    // If it called didReachTermination, it will then later call didExecuteConstraints.
    virtual void didExecuteConstraints();
    
    // After doing that, it will do synchronous draining. When this stalls - either due to timeout or
    // just 'cause, it will call this.
    virtual void synchronousDrainingDidStall();
    
    virtual MonotonicTime timeToStop() = 0; // Call while resumed, to ask when to stop.
    virtual MonotonicTime timeToResume() = 0; // Call while stopped, to ask when to resume.
    
    virtual void log();
    
    bool shouldStop(); // Call while resumed, to ask if we should stop now.
    bool shouldResume(); // Call while stopped, to ask if we should resume now.
    
    virtual void endCollection() = 0;
};

} // namespace JSC