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https://github.com/wpilibsuite/allwpilib
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62be0392b6
std::scoped_lock was introduced in C++17 and is strictly better than std::lock_guard as it supports locking any number of mutexes safely. It's also easier to use than std::lock for locking multiple mutexes at once.
89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
/*----------------------------------------------------------------------------*/
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/* Copyright (c) 2016-2019 FIRST. All Rights Reserved. */
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/* Open Source Software - may be modified and shared by FRC teams. The code */
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/* must be accompanied by the FIRST BSD license file in the root directory of */
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/* the project. */
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/*----------------------------------------------------------------------------*/
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#pragma once
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// Allows usage with std::scoped_lock without including <mutex> separately
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#ifdef __linux__
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#include <pthread.h>
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#endif
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#include <mutex>
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namespace wpi {
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#if defined(__FRC_ROBORIO__) && !defined(WPI_USE_PRIORITY_MUTEX)
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#define WPI_USE_PRIORITY_MUTEX
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#endif
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#if defined(WPI_USE_PRIORITY_MUTEX) && defined(__linux__)
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#define WPI_HAVE_PRIORITY_MUTEX 1
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class priority_recursive_mutex {
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public:
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using native_handle_type = pthread_mutex_t*;
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constexpr priority_recursive_mutex() noexcept = default;
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priority_recursive_mutex(const priority_recursive_mutex&) = delete;
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priority_recursive_mutex& operator=(const priority_recursive_mutex&) = delete;
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// Lock the mutex, blocking until it's available.
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void lock() { pthread_mutex_lock(&m_mutex); }
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// Unlock the mutex.
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void unlock() { pthread_mutex_unlock(&m_mutex); }
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// Tries to lock the mutex.
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bool try_lock() noexcept { return !pthread_mutex_trylock(&m_mutex); }
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pthread_mutex_t* native_handle() { return &m_mutex; }
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private:
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// Do the equivalent of setting PTHREAD_PRIO_INHERIT and
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// PTHREAD_MUTEX_RECURSIVE_NP.
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#ifdef __PTHREAD_MUTEX_HAVE_PREV
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pthread_mutex_t m_mutex = {
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{0, 0, 0, 0, 0x20 | PTHREAD_MUTEX_RECURSIVE_NP, __PTHREAD_SPINS, {0, 0}}};
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#else
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pthread_mutex_t m_mutex = {
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{0, 0, 0, 0x20 | PTHREAD_MUTEX_RECURSIVE_NP, 0, {__PTHREAD_SPINS}}};
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#endif
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};
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class priority_mutex {
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public:
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using native_handle_type = pthread_mutex_t*;
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constexpr priority_mutex() noexcept = default;
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priority_mutex(const priority_mutex&) = delete;
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priority_mutex& operator=(const priority_mutex&) = delete;
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// Lock the mutex, blocking until it's available.
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void lock() { pthread_mutex_lock(&m_mutex); }
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// Unlock the mutex.
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void unlock() { pthread_mutex_unlock(&m_mutex); }
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// Tries to lock the mutex.
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bool try_lock() noexcept { return !pthread_mutex_trylock(&m_mutex); }
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pthread_mutex_t* native_handle() { return &m_mutex; }
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private:
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// Do the equivalent of setting PTHREAD_PRIO_INHERIT.
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#ifdef __PTHREAD_MUTEX_HAVE_PREV
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pthread_mutex_t m_mutex = {{0, 0, 0, 0, 0x20, __PTHREAD_SPINS, {0, 0}}};
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#else
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pthread_mutex_t m_mutex = {{0, 0, 0, 0x20, 0, {__PTHREAD_SPINS}}};
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#endif
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};
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#endif // defined(WPI_USE_PRIORITY_MUTEX) && defined(__linux__)
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} // namespace wpi
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