1/*
2 * Copyright 2015 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8// This file is not part of the public Skia API.
9
10#ifndef SkSpinlock_DEFINED
11#define SkSpinlock_DEFINED
12
13#include "SkAtomics.h"
14
15#define SK_DECLARE_STATIC_SPINLOCK(name) namespace {} static SkPODSpinlock name
16
17// This class has no constructor and must be zero-initialized (the macro above does this).
18struct SkPODSpinlock {
19    void acquire() {
20        // To act as a mutex, we need an acquire barrier.
21        while(sk_atomic_exchange(&fLocked, true, sk_memory_order_acquire)) { /*spin*/ }
22    }
23    void release() {
24        // To act as a mutex, we need a release barrier.
25        sk_atomic_store(&fLocked, false, sk_memory_order_release);
26    }
27
28    bool fLocked;
29};
30
31// For non-global-static use cases, this is normally what you want.
32class SkSpinlock : public SkPODSpinlock {
33public:
34    SkSpinlock() { this->release(); }
35};
36
37#endif//SkSpinlock_DEFINED
38