Files
allwpilib/wpiutil/src/main/native/include/wpi/priority_mutex.h
Peter Johnson 8f1f64ffb6 Remove year from file copyright message (NFC) (#2972)
Also update copyright to include "and other WPILib contributors" and clarify
license referral language to not be restricted to FIRST teams.
2020-12-26 14:12:05 -08:00

86 lines
2.4 KiB
C++

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
#pragma once
// Allows usage with std::scoped_lock without including <mutex> separately
#ifdef __linux__
#include <pthread.h>
#endif
#include <mutex>
namespace wpi {
#if defined(__FRC_ROBORIO__) && !defined(WPI_USE_PRIORITY_MUTEX)
#define WPI_USE_PRIORITY_MUTEX
#endif
#if defined(WPI_USE_PRIORITY_MUTEX) && defined(__linux__)
#define WPI_HAVE_PRIORITY_MUTEX 1
class priority_recursive_mutex {
public:
using native_handle_type = pthread_mutex_t*;
constexpr priority_recursive_mutex() noexcept = default;
priority_recursive_mutex(const priority_recursive_mutex&) = delete;
priority_recursive_mutex& operator=(const priority_recursive_mutex&) = delete;
// Lock the mutex, blocking until it's available.
void lock() { pthread_mutex_lock(&m_mutex); }
// Unlock the mutex.
void unlock() { pthread_mutex_unlock(&m_mutex); }
// Tries to lock the mutex.
bool try_lock() noexcept { return !pthread_mutex_trylock(&m_mutex); }
pthread_mutex_t* native_handle() { return &m_mutex; }
private:
// Do the equivalent of setting PTHREAD_PRIO_INHERIT and
// PTHREAD_MUTEX_RECURSIVE_NP.
#ifdef __PTHREAD_MUTEX_HAVE_PREV
pthread_mutex_t m_mutex = {
{0, 0, 0, 0, 0x20 | PTHREAD_MUTEX_RECURSIVE_NP, __PTHREAD_SPINS, {0, 0}}};
#else
pthread_mutex_t m_mutex = {
{0, 0, 0, 0x20 | PTHREAD_MUTEX_RECURSIVE_NP, 0, {__PTHREAD_SPINS}}};
#endif
};
class priority_mutex {
public:
using native_handle_type = pthread_mutex_t*;
constexpr priority_mutex() noexcept = default;
priority_mutex(const priority_mutex&) = delete;
priority_mutex& operator=(const priority_mutex&) = delete;
// Lock the mutex, blocking until it's available.
void lock() { pthread_mutex_lock(&m_mutex); }
// Unlock the mutex.
void unlock() { pthread_mutex_unlock(&m_mutex); }
// Tries to lock the mutex.
bool try_lock() noexcept { return !pthread_mutex_trylock(&m_mutex); }
pthread_mutex_t* native_handle() { return &m_mutex; }
private:
// Do the equivalent of setting PTHREAD_PRIO_INHERIT.
#ifdef __PTHREAD_MUTEX_HAVE_PREV
pthread_mutex_t m_mutex = {{0, 0, 0, 0, 0x20, __PTHREAD_SPINS, {0, 0}}};
#else
pthread_mutex_t m_mutex = {{0, 0, 0, 0x20, 0, {__PTHREAD_SPINS}}};
#endif
};
#endif // defined(WPI_USE_PRIORITY_MUTEX) && defined(__linux__)
} // namespace wpi