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/*
* Copyright (c) 2017-2019 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <atomic>
namespace utils {
class SpinLock : private std::atomic_flag {
public:
class Acquire {
public:
Acquire(SpinLock& spin_lock) : spin_lock_(spin_lock) { spin_lock_.lock(); }
~Acquire() { spin_lock_.unlock(); }
// No copies
Acquire& operator=(const Acquire&) = delete;
Acquire(const Acquire&) = delete;
private:
SpinLock& spin_lock_;
};
SpinLock() { clear(); }
void lock() {
// busy-wait
while (std::atomic_flag::test_and_set(std::memory_order_acquire))
;
}
void unlock() { clear(std::memory_order_release); }
bool tryLock() {
return std::atomic_flag::test_and_set(std::memory_order_acquire);
}
};
} // namespace utils
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