| /* |
| * Copyright (C) 2014 Apple Inc. All rights reserved. |
| * Copyright (C) 2018 Yusuke Suzuki <utatane.tea@gmail.com>. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include "BAssert.h" |
| #include <atomic> |
| #include <mutex> |
| #include <thread> |
| |
| // A fast replacement for std::mutex. |
| |
| namespace bmalloc { |
| |
| class Mutex { |
| public: |
| constexpr Mutex() = default; |
| |
| void lock(); |
| bool try_lock(); |
| void unlock(); |
| |
| private: |
| BEXPORT void lockSlowCase(); |
| |
| std::atomic<bool> m_flag { false }; |
| std::atomic<bool> m_isSpinning { false }; |
| }; |
| |
| static inline void sleep( |
| std::unique_lock<Mutex>& lock, std::chrono::milliseconds duration) |
| { |
| if (duration == std::chrono::milliseconds(0)) |
| return; |
| |
| lock.unlock(); |
| std::this_thread::sleep_for(duration); |
| lock.lock(); |
| } |
| |
| static inline void waitUntilFalse( |
| std::unique_lock<Mutex>& lock, std::chrono::milliseconds sleepDuration, |
| bool& condition) |
| { |
| while (condition) { |
| condition = false; |
| sleep(lock, sleepDuration); |
| } |
| } |
| |
| inline bool Mutex::try_lock() |
| { |
| return !m_flag.exchange(true, std::memory_order_acquire); |
| } |
| |
| inline void Mutex::lock() |
| { |
| if (!try_lock()) |
| lockSlowCase(); |
| } |
| |
| inline void Mutex::unlock() |
| { |
| m_flag.store(false, std::memory_order_release); |
| } |
| |
| } // namespace bmalloc |