timed_mutex.hpp

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/*
 * Copyright 2016, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
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 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 */

#ifndef PMEMOBJ_TIMED_MUTEX_HPP
#define PMEMOBJ_TIMED_MUTEX_HPP

#include <chrono>

#include "libpmemobj++/detail/conversions.hpp"
#include "libpmemobj/thread.h"

namespace nvml
{

namespace obj
{

class timed_mutex {
    typedef std::chrono::system_clock clock_type;

public:
    typedef PMEMmutex *native_handle_type;

    timed_mutex() noexcept = default;

    ~timed_mutex() = default;

    void
    lock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_mutex_lock(pop, &this->plock))
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a mutex.");
    }

    bool
    try_lock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        int ret = pmemobj_mutex_trylock(pop, &this->plock);

        if (ret == 0)
            return true;
        else if (ret == EBUSY)
            return false;
        else
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a mutex.");
    }

    template <typename Clock, typename Duration>
    bool
    try_lock_until(
        const std::chrono::time_point<Clock, Duration> &timeout_time)
    {
        return timedlock_impl(timeout_time);
    }

    template <typename Rep, typename Period>
    bool
    try_lock_for(const std::chrono::duration<Rep, Period> &timeout_duration)
    {
        return timedlock_impl(clock_type::now() + timeout_duration);
    }

    void
    unlock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_mutex_unlock(pop, &this->plock))
            throw lock_error(ret, std::system_category(),
                     "Failed to unlock a mutex.");
    }

    native_handle_type
    native_handle() noexcept
    {
        return &this->plock;
    }

    timed_mutex &operator=(const timed_mutex &) = delete;

    timed_mutex(const timed_mutex &) = delete;

private:
    template <typename Clock, typename Duration>
    bool
    timedlock_impl(const std::chrono::time_point<Clock, Duration> &abs_time)
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);

        /* convert to my clock */
        const typename Clock::time_point their_now = Clock::now();
        const clock_type::time_point my_now = clock_type::now();
        const auto delta = abs_time - their_now;
        const auto my_abs = my_now + delta;

        struct timespec ts = detail::timepoint_to_timespec(my_abs);

        auto ret = pmemobj_mutex_timedlock(pop, &this->plock, &ts);

        if (ret == 0)
            return true;
        else if (ret == ETIMEDOUT)
            return false;
        else
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a mutex");
    }

    PMEMmutex plock;
};

} /* namespace obj */

} /* namespace nvml */

#endif /* PMEMOBJ_TIMED_MUTEX_HPP */