/*
* Copyright (C) 2013 Google 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:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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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* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/
#ifndef WTF_SpinLock_h
#define WTF_SpinLock_h
// DESCRIPTION
// spinLockLock() and spinLockUnlock() are simple spinlock primitives based on
// the standard CPU primitive of atomic increment and decrement of an int at
// a given memory address.
#include "wtf/Atomics.h"
namespace WTF {
ALWAYS_INLINE void spinLockLock(int volatile* lock)
{
while (UNLIKELY(atomicTestAndSetToOne(lock))) {
while (*lock) { } // Spin without spamming locked instructions.
}
}
ALWAYS_INLINE void spinLockUnlock(int volatile* lock)
{
atomicSetOneToZero(lock);
}
} // namespace WTF
using WTF::spinLockLock;
using WTF::spinLockUnlock;
#endif // WTF_SpinLock_h