pthread::condition_variable Class Reference

#include <condition_variable.hpp>

Public Member Functions
void	wait (mutex &mtx)
void	wait (lock_guard< pthread::mutex > lck)
template<class Lambda >
bool	wait (mutex &mtx, Lambda lambda)
template<class Lambda >
bool	wait (lock_guard< pthread::mutex > &lck, Lambda lambda)
cv_status	wait_for (mutex &mtx, int millis)
cv_status	wait_for (lock_guard< pthread::mutex > &lck, int millis)
template<class Lambda >
bool	wait_for (mutex &mtx, int millis, Lambda lambda)
template<class Lambda >
bool	wait_for (lock_guard< pthread::mutex > &lck, int millis, Lambda lambda)
void	notify_one () noexcept
void	notify_all () noexcept

Detailed Description

Condition variable.

The condition_variable class is a synchronization primitive that can be used to block a thread, or multiple threads at the same time, until another thread both modifies a shared variable (the condition), and notifies the condition_variable.

The thread that intends to modify the variable has to

• acquire a pthread::mutex (typically via pthread::lock_guard)
• perform the modification while the lock is held
• execute notify_one or notify_all on the pthread::condition_variable (the lock does not need to be held for notification)

Even if the shared variable is atomic, it must be modified under the mutex in order to correctly publish the modification to the waiting thread.

Upon successful return, the mutex shall have been locked and shall be owned by the calling thread.

Author

herbert koelman (herbe.nosp@m.rt.k.nosp@m.oelma.nosp@m.n@me.nosp@m..com)

Definition at line 56 of file condition_variable.hpp.

Member Function Documentation

void pthread::condition_variable::notify_all ( )

noexcept

Signal all waiting threads.

The call unblocks all threads currently blocked on the specified condition variable cond.

Definition at line 61 of file condition_variable.cpp.

void pthread::condition_variable::notify_one ( )

noexcept

Signal one waiting thread.

The call unblocks at least one of the threads that are blocked on the specified condition variable cond (if any threads are blocked on cond).

Definition at line 53 of file condition_variable.cpp.

void pthread::condition_variable::wait

(

mutex &

mtx

)

Wait for condition to be signaled.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

Parameters

mtx	ralated mutex, which must be locked by the current thread.

See also

notify_one

notify_all

Definition at line 5 of file condition_variable.cpp.

void pthread::condition_variable::wait

(

lock_guard< pthread::mutex >

lck

)

See also

wai

Definition at line 9 of file condition_variable.cpp.

template<class Lambda >

bool pthread::condition_variable::wait	(	mutex &	mtx,
		Lambda	lambda
	)

Wait for condition to be signaled.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

The lambda (closure) is run to check if the condition was met. Lambda should return false if the waiting should be continued. The signature of the predicate function should be equivalent to the following: bool pred();

Parameters

mtx	ralated mutex, which must be locked by the current thread.
lambda	run to check if condition was met.

Returns

true if lmabda returned true.

See also

notify_one

notify_all

Definition at line 209 of file condition_variable.hpp.

template<class Lambda >

bool pthread::condition_variable::wait	(	lock_guard< pthread::mutex > &	lck,
		Lambda	lambda
	)

Wait for condition to be signaled.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

The lambda (closure) is run to check if the condition was met. Lambda should return false if the waiting should be continued. The signature of the predicate function should be equivalent to the following: bool pred();

Parameters

lck	ralated mutex lock_guard, which must be locked by the current thread.
lambda	run to check if condition was met.

Returns

true if lmabda returned true.

See also

notify_one

notify_all

Definition at line 221 of file condition_variable.hpp.

cv_status pthread::condition_variable::wait_for	(	mutex &	mtx,
		int	millis
	)

Wait for condition to be signaled within given time frame.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

If this method is called with millis < 0 then the timeout time is not recalculated. This make it possible to handle spurious unblocking of condition variable without the need of a lambda expression. The call sequence is then: while(! check_condition() && wait_for(lck, 200) == no_tiemout );

Parameters

mtx	ralated mutex, which must be locked by the current thread.
millis	milliseconds to wait for this instance to signaled.

Returns

cv_status (either timeout or no_timeout)

Exceptions

condition_variable_exception

is thrown either if timeout calculation failed or mutex ownership was wrong.

See also

notify_one

notify_all

Definition at line 20 of file condition_variable.cpp.

cv_status pthread::condition_variable::wait_for	(	lock_guard< pthread::mutex > &	lck,
		int	millis
	)

See also

wait_for (mutex &, int)

Definition at line 14 of file condition_variable.cpp.

template<class Lambda >

bool pthread::condition_variable::wait_for	(	mutex &	mtx,
		int	millis,
		Lambda	lambda
	)

Wait for condition to be signaled within a given time frame.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

The lambda (closure) is run to check if the condition was met. Lambda should return false if the waiting should be continued. The signature of the predicate function should be equivalent to the following: bool lambda();

Parameters

mtx	ralated mutex, which must be locked by the current thread.
millis	milli seconds to wait for condition to be signaled.
lambda	run to check if condition was met.

Returns

true if lmabda returned true.

See also

notify_one

notify_all

Definition at line 227 of file condition_variable.hpp.

template<class Lambda >

bool pthread::condition_variable::wait_for	(	lock_guard< pthread::mutex > &	lck,
		int	millis,
		Lambda	lambda
	)

Wait for condition to be signaled within a given time frame.

This method atomically release mutex and cause the calling thread to block; atomically here means "atomically with respect to access by another thread to the mutex and then the condition variable". Call notify_one or notify_all to signal the condition.

Upon successful return, the mutex has been locked and is owned by the calling thread.

The lambda (closure) is run to check if the condition was met. Lambda should return false if the waiting should be continued. The signature of the predicate function should be equivalent to the following: bool lambda();

Parameters

lck	ralated mutex lock_guard, which must be locked by the current thread.
millis	milli seconds to wait for condition to be signaled.
lambda	run to check if condition was met.

Returns

true if lmabda returned true.

See also

notify_one

notify_all

Definition at line 263 of file condition_variable.hpp.

---

The documentation for this class was generated from the following files:

• include/pthread/condition_variable.hpp
• src/condition_variable.cpp