/*
* Copyright 2016-2018, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * 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.
*
* * Neither the name of the copyright holder nor the names of its
* 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
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER 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,
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* 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.
*/
/**
* @file
* Pmem-resident timed_mutex.
*/
#ifndef LIBPMEMOBJ_CPP_TIMED_MUTEX_HPP
#define LIBPMEMOBJ_CPP_TIMED_MUTEX_HPP
#include <chrono>
#include <libpmemobj++/detail/conversions.hpp>
#include <libpmemobj/thread.h>
namespace pmem
{
namespace obj
{
/**
* Persistent memory resident timed_mutex implementation.
*
* This class is an implementation of a PMEM-resident timed_mutex
* which mimics in behavior the C++11 std::timed_mutex. This class
* satisfies all requirements of the TimedMutex and StandardLayoutType
* concepts. The typical usage example would be:
* @snippet doc_snippets/mutex.cpp timed_mutex_example
*/
class timed_mutex {
typedef std::chrono::system_clock clock_type;
public:
/** Implementation defined handle to the native type. */
typedef PMEMmutex *native_handle_type;
/**
* Default constructor.
*
* @throw lock_error when the timed_mutex is not from persistent memory.
*/
timed_mutex()
{
PMEMobjpool *pop;
if ((pop = pmemobj_pool_by_ptr(&plock)) == nullptr)
throw lock_error(
1, std::generic_category(),
"Persistent mutex not from persistent memory.");
pmemobj_mutex_zero(pop, &plock);
}
/**
* Defaulted destructor.
*/
~timed_mutex() = default;
/**
* Locks the mutex, blocks if already locked.
*
* If a different thread already locked this mutex, the calling
* thread will block. If the same thread tries to lock a mutex
* it already owns, the behavior is undefined.
*
* @throw lock_error when an error occurs, this includes all
* system related errors with the underlying implementation of
* the mutex.
*/
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.");
}
/**
* Tries to lock the mutex, returns regardless if the lock
* succeeds.
*
* If the same thread tries to lock a mutex it already owns,
* the behavior is undefined.
*
* @return `true` on successful lock acquisition, `false`
* otherwise.
*
* @throw lock_error when an error occurs, this includes all
* system related errors with the underlying implementation of
* the 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.");
}
/**
* Makes the current thread block until the lock is acquired or a
* specific time is reached.
*
* If the same thread tries to lock a mutex it already owns,
* the behavior is undefined.
*
* @param[in] timeout_time a specific point in time, which when
* reached unblocks the thread.
*
* @return `true` on successful lock acquisition, `false`
* otherwise.
*
* @throw lock_error when an error occurs, this includes all
* system related errors with the underlying implementation of
* the mutex.
*/
template <typename Clock, typename Duration>
bool
try_lock_until(
const std::chrono::time_point<Clock, Duration> &timeout_time)
{
return timedlock_impl(timeout_time);
}
/**
* Makes the current thread block until the lock is acquired or a
* specified amount of time passes.
*
* If the same thread tries to lock a mutex it already owns,
* the behavior is undefined.
*
* @param[in] timeout_duration a specific duration, which when
* expired unblocks the thread.
*
* @return `true` on successful lock acquisition, `false`
* otherwise.
*
* @throw lock_error when an error occurs, this includes all
* system related errors with the underlying implementation of
* the mutex.
*/
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);
}
/**
* Unlocks a previously locked mutex.
*
* Unlocking a mutex that has not been locked by the current
* thread results in undefined behavior. Unlocking a mutex that
* has not been lock also results in undefined behavior.
*/
void
unlock()
{
PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
int ret = pmemobj_mutex_unlock(pop, &this->plock);
if (ret)
throw lock_error(ret, std::system_category(),
"Failed to unlock a mutex.");
}
/**
* Access a native handle to this condition variable.
*
* @return a pointer to PMEMmutex.
*/
native_handle_type
native_handle() noexcept
{
return &this->plock;
}
/**
* Deleted assignment operator.
*/
timed_mutex &operator=(const timed_mutex &) = delete;
/**
* Deleted copy constructor.
*/
timed_mutex(const timed_mutex &) = delete;
private:
/**
* Internal implementation of the timed lock call.
*/
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");
}
/** A POSIX style PMEM-resident timed_mutex.*/
PMEMmutex plock;
};
} /* namespace obj */
} /* namespace pmem */
#endif /* LIBPMEMOBJ_CPP_TIMED_MUTEX_HPP */