/*
* 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,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* 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 condition variable.
*/
#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
{
/**
* Persistent memory resident condition variable.
*
* This class is an implementation of a PMEM-resident condition
* variable which mimics in behavior the C++11 std::condition_variable. The
* typical usage example would be:
* @snippet doc_snippets/mutex.cpp cond_var_example
*/
class condition_variable {
typedef std::chrono::system_clock clock_type;
public:
/** The handle typedef to the underlying basic type. */
typedef PMEMcond *native_handle_type;
/**
* Default constructor.
*
* @throw lock_error when the condition_variable is not from persistent
* memory.
*/
condition_variable()
{
PMEMobjpool *pop;
if ((pop = pmemobj_pool_by_ptr(&pcond)) == nullptr)
throw lock_error(
1, std::generic_category(),
"Persistent condition variable not from persistent memory.");
pmemobj_cond_zero(pop, &pcond);
}
/**
* Defaulted destructor.
*/
~condition_variable() = default;
/**
* Notify and unblock one thread waiting on `*this` condition.
*
* Does nothing when no threads are waiting. It is unspecified
* which thread is selected for unblocking.
*
* @throw lock_error when the signal fails on the #pcond.
*/
void
notify_one()
{
PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
if (int ret = pmemobj_cond_signal(pop, &this->pcond))
throw lock_error(
ret, std::system_category(),
"Error notifying one on a condition variable.");
}
/**
* Notify and unblock all threads waiting on `*this` condition.
*
* Does nothing when no threads are waiting.
*/
void
notify_all()
{
PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
if (int ret = pmemobj_cond_broadcast(pop, &this->pcond))
throw lock_error(
ret, std::system_category(),
"Error notifying all on a condition variable.");
}
/**
* Makes the current thread block until the condition variable
* is notified or it is woken up by some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
void
wait(mutex &lock)
{
this->wait_impl(lock);
}
/**
* Makes the current thread block until the condition variable
* is notified or it is woken up by some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
*
* @throw lock_error when unlocking the lock or waiting
* on #pcond fails.
*/
template <typename Lock>
void
wait(Lock &lock)
{
this->wait_impl(*lock.mutex());
}
/**
* Makes the current thread block until the condition variable
* is notified.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
* This version is immune to spurious wake ups due to the
* provided predicate.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
template <typename Predicate>
void
wait(mutex &lock, Predicate pred)
{
this->wait_impl(lock, std::move(pred));
}
/**
* Makes the current thread block until the condition variable
* is notified.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
* This version is immune to spurious wake ups due to the
* provided predicate.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
template <typename Lock, typename Predicate>
void
wait(Lock &lock, Predicate pred)
{
this->wait_impl(*lock.mutex(), std::move(pred));
}
/**
* Makes the current thread block until the condition variable
* is notified, a specific time is reached or it is woken up by
* some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
* @param[in] timeout a specific point in time, which when
* reached unblocks the thread.
*
* @return std::cv_status::timeout on timeout,
* std::cv_status::no_timeout otherwise.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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);
}
/**
* Makes the current thread block until the condition variable
* is notified, a specific time is reached or it is woken up by
* some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
* @param[in] timeout a specific point in time, which when
* reached unblocks the thread.
*
* @return std::cv_status::timeout on timeout,
* std::cv_status::no_timeout otherwise.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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);
}
/**
* Makes the current thread block until the condition variable
* is notified or a specific time is reached.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
* @param[in] timeout a specific point in time, which when
* reached unblocks the thread.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @return `false` if pred evaluates to `false` after timeout
* expired, otherwise `true`.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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));
}
/**
* Makes the current thread block until the condition variable
* is notified or a specific time is reached.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
* @param[in] timeout a specific point in time, which when
* reached unblocks the thread.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @return `false` if pred evaluates to `false` after timeout
* expired, otherwise `true`.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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));
}
/**
* Makes the current thread block until the condition variable
* is notified, the specified amount of time passes or it is
* woken up by some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
* @param[in] rel_time a specific duration, which when
* expired unblocks the thread.
*
* @return std::cv_status::timeout on timeout,
* std::cv_status::no_timeout otherwise.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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);
}
/**
* Makes the current thread block until the condition variable
* is notified or the specified amount of time passes.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a Lock object which meets the
* BasicLockableConcept. Needs to be based on a PMEM-resident
* obj::mutex.
* @param[in] rel_time a specific duration, which when
* expired unblocks the thread.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @return `false` if pred evaluates to `false` after timeout
* expired, otherwise `true`.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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));
}
/**
* Makes the current thread block until the condition variable
* is notified, the specified amount of time passes or it is
* woken up by some other measure.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
* @param[in] rel_time a specific duration, which when
* expired unblocks the thread.
*
* @return std::cv_status::timeout on timeout,
* std::cv_status::no_timeout otherwise.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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);
}
/**
* Makes the current thread block until the condition variable
* is notified or the specified amount of time passes.
*
* This releases the lock, blocks the current thread and adds
* it to the list of threads waiting on `*this` condition
* variable. The lock needs to be acquired and owned by the
* calling thread. The lock is automatically reacquired after
* the call to wait.
*
* @param[in,out] lock a PMEM-resident obj::mutex.
* @param[in] rel_time a specific duration, which when
* expired unblocks the thread.
* @param[in] pred predicate which returns `false` if waiting is
* to be continued.
*
* @return `false` if pred evaluates to `false` after timeout
* expired, otherwise `true`.
*
* @throw lock_error when unlocking the lock or waiting on
* #pcond fails.
*/
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));
}
/**
* Access a native handle to this condition variable.
*
* @return a pointer to PMEMcond.
*/
native_handle_type
native_handle() noexcept
{
return &this->pcond;
}
/**
* Deleted assignment operator.
*/
condition_variable &operator=(const condition_variable &) = delete;
/**
* Deleted copy constructor.
*/
condition_variable(const condition_variable &) = delete;
private:
/**
* Internal implementation of the wait call.
*/
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 lock_error(
ret, std::system_category(),
"Error waiting on a condition variable.");
}
/**
* Internal implementation of the wait call.
*/
template <typename Predicate>
void
wait_impl(mutex &lock, Predicate pred)
{
while (!pred())
this->wait(lock);
}
/**
* Internal implementation of the wait_until call.
*/
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 lock_error(
ret, std::system_category(),
"Error waiting on a condition variable.");
}
/**
* Internal implementation of the wait_until call.
*/
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;
}
/** A POSIX style PMEM-resident condition variable.*/
PMEMcond pcond;
};
} /* namespace obj */
} /* namespace pmem */
#endif /* LIBPMEMOBJ_CPP_CONDVARIABLE_HPP */