condition_variable.hpp

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// SPDX-License-Identifier: BSD-3-Clause
/* Copyright 2016-2020, Intel Corporation */
 
#ifndef LIBPMEMOBJ_CPP_CONDVARIABLE_HPP
#define LIBPMEMOBJ_CPP_CONDVARIABLE_HPP
 
#include <chrono>
#include <condition_variable>
 
#include <libpmemobj++/detail/conversions.hpp>
#include <libpmemobj++/mutex.hpp>
#include <libpmemobj/thread.h>
 
namespace pmem
{
 
namespace obj
{
 
class condition_variable {
    typedef std::chrono::system_clock clock_type;
 
public:
    typedef PMEMcond *native_handle_type;
 
    condition_variable()
    {
        PMEMobjpool *pop;
        if ((pop = pmemobj_pool_by_ptr(&pcond)) == nullptr)
            throw pmem::lock_error(
                1, std::generic_category(),
                "Persistent condition variable not from persistent memory.");
 
        pmemobj_cond_zero(pop, &pcond);
    }
 
    ~condition_variable() = default;
 
    void
    notify_one()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_cond_signal(pop, &this->pcond))
            throw pmem::lock_error(
                ret, std::system_category(),
                "Error notifying one on a condition variable.")
                .with_pmemobj_errormsg();
    }
 
    void
    notify_all()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_cond_broadcast(pop, &this->pcond))
            throw pmem::lock_error(
                ret, std::system_category(),
                "Error notifying all on a condition variable.")
                .with_pmemobj_errormsg();
    }
 
    void
    wait(mutex &lock)
    {
        this->wait_impl(lock);
    }
 
    template <typename Lock>
    void
    wait(Lock &lock)
    {
        this->wait_impl(*lock.mutex());
    }
 
    template <typename Predicate>
    void
    wait(mutex &lock, Predicate pred)
    {
        this->wait_impl(lock, std::move(pred));
    }
 
    template <typename Lock, typename Predicate>
    void
    wait(Lock &lock, Predicate pred)
    {
        this->wait_impl(*lock.mutex(), std::move(pred));
    }
 
    template <typename Clock, typename Duration>
    std::cv_status
    wait_until(mutex &lock,
           const std::chrono::time_point<Clock, Duration> &timeout)
    {
        return this->wait_until_impl(lock, timeout);
    }
 
    template <typename Lock, typename Clock, typename Duration>
    std::cv_status
    wait_until(Lock &lock,
           const std::chrono::time_point<Clock, Duration> &timeout)
    {
        return this->wait_until_impl(*lock.mutex(), timeout);
    }
 
    template <typename Clock, typename Duration, typename Predicate>
    bool
    wait_until(mutex &lock,
           const std::chrono::time_point<Clock, Duration> &timeout,
           Predicate pred)
    {
        return this->wait_until_impl(lock, timeout, std::move(pred));
    }
 
    template <typename Lock, typename Clock, typename Duration,
          typename Predicate>
    bool
    wait_until(Lock &lock,
           const std::chrono::time_point<Clock, Duration> &timeout,
           Predicate pred)
    {
        return this->wait_until_impl(*lock.mutex(), timeout,
                         std::move(pred));
    }
 
    template <typename Lock, typename Rep, typename Period>
    std::cv_status
    wait_for(Lock &lock, const std::chrono::duration<Rep, Period> &rel_time)
    {
        return this->wait_until_impl(*lock.mutex(),
                         clock_type::now() + rel_time);
    }
 
    template <typename Lock, typename Rep, typename Period,
          typename Predicate>
    bool
    wait_for(Lock &lock, const std::chrono::duration<Rep, Period> &rel_time,
         Predicate pred)
    {
        return this->wait_until_impl(*lock.mutex(),
                         clock_type::now() + rel_time,
                         std::move(pred));
    }
 
    template <typename Rep, typename Period>
    std::cv_status
    wait_for(mutex &lock,
         const std::chrono::duration<Rep, Period> &rel_time)
    {
        return this->wait_until_impl(lock,
                         clock_type::now() + rel_time);
    }
 
    template <typename Rep, typename Period, typename Predicate>
    bool
    wait_for(mutex &lock,
         const std::chrono::duration<Rep, Period> &rel_time,
         Predicate pred)
    {
        return this->wait_until_impl(lock, clock_type::now() + rel_time,
                         std::move(pred));
    }
 
    native_handle_type
    native_handle() noexcept
    {
        return &this->pcond;
    }
 
    condition_variable &operator=(const condition_variable &) = delete;
 
    condition_variable(const condition_variable &) = delete;
 
private:
    void
    wait_impl(mutex &lock)
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_cond_wait(pop, &this->pcond,
                        lock.native_handle()))
            throw pmem::lock_error(
                ret, std::system_category(),
                "Error waiting on a condition variable.")
                .with_pmemobj_errormsg();
    }
 
    template <typename Predicate>
    void
    wait_impl(mutex &lock, Predicate pred)
    {
        while (!pred())
            this->wait(lock);
    }
 
    template <typename Clock, typename Duration>
    std::cv_status
    wait_until_impl(
        mutex &lock,
        const std::chrono::time_point<Clock, Duration> &abs_timeout)
    {
        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_timeout - their_now;
        const auto my_rel = my_now + delta;
 
        struct timespec ts = detail::timepoint_to_timespec(my_rel);
 
        auto ret = pmemobj_cond_timedwait(pop, &this->pcond,
                          lock.native_handle(), &ts);
 
        if (ret == 0)
            return std::cv_status::no_timeout;
        else if (ret == ETIMEDOUT)
            return std::cv_status::timeout;
        else
            throw pmem::lock_error(
                ret, std::system_category(),
                "Error waiting on a condition variable.")
                .with_pmemobj_errormsg();
    }
 
    template <typename Clock, typename Duration, typename Predicate>
    bool
    wait_until_impl(
        mutex &lock,
        const std::chrono::time_point<Clock, Duration> &abs_timeout,
        Predicate pred)
    {
        while (!pred())
            if (this->wait_until_impl(lock, abs_timeout) ==
                std::cv_status::timeout)
                return pred();
        return true;
    }
 
    PMEMcond pcond;
};
 
} /* namespace obj */
 
} /* namespace pmem */
 
#endif /* LIBPMEMOBJ_CPP_CONDVARIABLE_HPP */