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48 lines
1.3 KiB
48 lines
1.3 KiB
4 months ago
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/*
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* Copyright 2015 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkSpinlock_DEFINED
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#define SkSpinlock_DEFINED
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#include "SkTypes.h"
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#include <atomic>
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class SkSpinlock {
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public:
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constexpr SkSpinlock() = default;
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void acquire() {
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// To act as a mutex, we need an acquire barrier when we acquire the lock.
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if (fLocked.exchange(true, std::memory_order_acquire)) {
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// Lock was contended. Fall back to an out-of-line spin loop.
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this->contendedAcquire();
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}
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}
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// Acquire the lock or fail (quickly). Lets the caller decide to do something other than wait.
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bool tryAcquire() {
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// To act as a mutex, we need an acquire barrier when we acquire the lock.
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if (fLocked.exchange(true, std::memory_order_acquire)) {
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// Lock was contended. Let the caller decide what to do.
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return false;
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}
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return true;
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}
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void release() {
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// To act as a mutex, we need a release barrier when we release the lock.
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fLocked.store(false, std::memory_order_release);
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}
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private:
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SK_API void contendedAcquire();
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std::atomic<bool> fLocked{false};
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};
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#endif//SkSpinlock_DEFINED
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