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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
// This file is not part of the public Skia API.
#ifndef SkSpinlock_DEFINED
#define SkSpinlock_DEFINED
#include "SkAtomics.h"
#define SK_DECLARE_STATIC_SPINLOCK(name) namespace {} static SkPODSpinlock name
// This class has no constructor and must be zero-initialized (the macro above does this).
class SK_API SkPODSpinlock {
public:
void acquire() {
// To act as a mutex, we need an acquire barrier if we take the lock.
if (sk_atomic_exchange(&fLocked, true, sk_memory_order_acquire)) {
// Lock was contended. Fall back to an out-of-line spin loop.
this->contendedAcquire();
}
}
void release() {
// To act as a mutex, we need a release barrier.
sk_atomic_store(&fLocked, false, sk_memory_order_release);
}
private:
void contendedAcquire();
bool fLocked;
};
// For non-global-static use cases, this is normally what you want.
class SkSpinlock : public SkPODSpinlock {
public:
SkSpinlock() { this->release(); }
};
#endif//SkSpinlock_DEFINED
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