PerformanceTests/StitchMarker/wtf/WTFThreadData.h

/*
 * Copyright (C) 2008-2017 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.
 *
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#ifndef WTFThreadData_h
#define WTFThreadData_h

#include <wtf/FastTLS.h>
#include <wtf/Noncopyable.h>
#include <wtf/StackBounds.h>
#include <wtf/StackStats.h>
#include <wtf/ThreadSpecific.h>

namespace WTF {

class AtomicStringTable;

typedef void (*AtomicStringTableDestructor)(AtomicStringTable*);

class WTFThreadData {
    WTF_MAKE_NONCOPYABLE(WTFThreadData);
public:
    WTF_EXPORT_PRIVATE WTFThreadData();
    WTF_EXPORT_PRIVATE ~WTFThreadData();

    AtomicStringTable* atomicStringTable()
    {
        return m_currentAtomicStringTable;
    }

    AtomicStringTable* setCurrentAtomicStringTable(AtomicStringTable* atomicStringTable)
    {
        AtomicStringTable* oldAtomicStringTable = m_currentAtomicStringTable;
        m_currentAtomicStringTable = atomicStringTable;
        return oldAtomicStringTable;
    }

    const StackBounds& stack()
    {
        return m_stackBounds;
    }

#if ENABLE(STACK_STATS)
    StackStats::PerThreadStats& stackStats()
    {
        return m_stackStats;
    }
#endif

    void* savedStackPointerAtVMEntry()
    {
        return m_savedStackPointerAtVMEntry;
    }

    void setSavedStackPointerAtVMEntry(void* stackPointerAtVMEntry)
    {
        m_savedStackPointerAtVMEntry = stackPointerAtVMEntry;
    }

    void* savedLastStackTop()
    {
        return m_savedLastStackTop;
    }

    void setSavedLastStackTop(void* lastStackTop)
    {
        m_savedLastStackTop = lastStackTop;
    }

    void* m_apiData { nullptr };

private:
    AtomicStringTable* m_currentAtomicStringTable { nullptr };
    AtomicStringTable* m_defaultAtomicStringTable { nullptr };
    AtomicStringTableDestructor m_atomicStringTableDestructor { nullptr };

    StackBounds m_stackBounds;
#if ENABLE(STACK_STATS)
    StackStats::PerThreadStats m_stackStats;
#endif
    void* m_savedStackPointerAtVMEntry { nullptr };
    void* m_savedLastStackTop;

#if HAVE(FAST_TLS)
    WTF_EXPORT_PRIVATE static WTFThreadData& createAndRegisterForGetspecificDirect();
#else
    static WTF_EXPORTDATA ThreadSpecific<WTFThreadData>* staticData;
#endif

    friend WTFThreadData& wtfThreadData();
    friend class AtomicStringTable;
};

inline WTFThreadData& wtfThreadData()
{
    // WRT WebCore:
    //    WTFThreadData is used on main thread before it could possibly be used
    //    on secondary ones, so there is no need for synchronization here.
    // WRT JavaScriptCore:
    //    wtfThreadData() is initially called from initializeThreading(), ensuring
    //    this is initially called in a pthread_once locked context.
#if !HAVE(FAST_TLS)
    if (!WTFThreadData::staticData)
        WTFThreadData::staticData = new ThreadSpecific<WTFThreadData>;
    return **WTFThreadData::staticData;
#else
    if (WTFThreadData* data = static_cast<WTFThreadData*>(_pthread_getspecific_direct(WTF_THREAD_DATA_KEY)))
        return *data;
    return WTFThreadData::createAndRegisterForGetspecificDirect();
#endif
}

} // namespace WTF

using WTF::WTFThreadData;
using WTF::wtfThreadData;
using WTF::AtomicStringTable;

#endif // WTFThreadData_h