Source/heap/ThreadState.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * in the documentation and/or other materials provided with the
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#ifndef ThreadState_h
#define ThreadState_h

#include "wtf/HashSet.h"
#include "wtf/ThreadSpecific.h"
#include "wtf/Threading.h"

namespace WebCore {

class ThreadState {
public:
    // Initialize threading infrastructure. Should be called from the main
    // thread.
    static void init(intptr_t* startOfStack);
    static void shutdown();

    // Associate ThreadState object with the current thread. After this
    // call thread can start using the garbage collected heap infrastructure.
    // It also has to periodically check for safepoints.
    static void attach(intptr_t* startOfStack);

    // Disassociate attached ThreadState from the current thread. The thread
    // can no longer use the garbage collected heap after this call.
    static void detach();

    static ThreadState* current() { return **s_threadSpecific; }
    static ThreadState* mainThreadState()
    {
        return reinterpret_cast<ThreadState*>(s_mainThreadStateStorage);
    }

    static bool isMainThread() { return current() == mainThreadState(); }

    inline void checkThread() const
    {
        ASSERT(m_thread == currentThread());
    }

private:
    explicit ThreadState(intptr_t* startOfStack);
    ~ThreadState();

    typedef HashSet<ThreadState*> AttachedThreadStateSet;
    static AttachedThreadStateSet& attachedThreads();

    static WTF::ThreadSpecific<ThreadState*>* s_threadSpecific;

    // We can't create a static member of type ThreadState here
    // because it will introduce global constructor and destructor.
    // We would like to manage lifetime of the ThreadState attached
    // to the main thread explicitly instead and still use normal
    // constructor and destructor for the ThreadState class.
    // For this we reserve static storage for the main ThreadState
    // and lazily construct ThreadState in it using placement new.
    static uint8_t s_mainThreadStateStorage[];

    ThreadIdentifier m_thread;
    intptr_t* m_startOfStack;
};

}

#endif // ThreadState_h