#Qnx semaphor how to
#Qnx semaphor software

#Qnx semaphor software

The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. See also tryAcquire(), try_acquire(), and try_acquire_for().ĭocumentation contributions included herein are the copyrights of The function returns true on acquiring the resource successfully. It is equivalent to calling tryAcquire(1, tp - Clock::now()), which means that the tp (time point) is recorded, ignoring the adjustments to Clock while waiting. template bool QSemaphore:: try_acquire_until(const std::chrono::time_point & tp) See also tryAcquire(), try_acquire(), and try_acquire_until(). It is equivalent to calling tryAcquire(1, timeout), where the call times out on the given timeout value. template bool QSemaphore:: try_acquire_for(const std::chrono::duration & timeout) See also tryAcquire(), try_acquire_for(), and try_acquire_until().

It is equivalent to calling tryAcquire(1), where the function returns true on acquiring the resource successfully. This function is provided for std::counting_semaphore compatibility. template bool QSemaphore:: tryAcquire( int n, std::chrono::duration timeout) tryAcquire( 3, 30000) // sem.available() = 2, returns true without waiting tryAcquire( 250, 1000) // sem.available() = 5, waits 1000 milliseconds and returns false See also QSemaphoreReleaser, QMutex, QWaitCondition, QThread, and Semaphores Example. If a party of 10 people want to be seated, but there are only 9 seats, those 10 people will wait, but a party of 4 people would be seated (taking the available seats to 5, making the party of 10 people wait longer). As people leave, the available() is incremented, allowing more people to enter. As seats are filled, available() is decremented. A semaphore is initialized with the number of chairs in the restaurant.

#Qnx semaphor how to

The Semaphores Example shows how to use QSemaphore to solve that problem.Ī non-computing example of a semaphore would be dining at a restaurant. tryAcquire( 250) // sem.available() = 9, returns falseĪ typical application of semaphores is for controlling access to a circular buffer shared by a producer thread and a consumer thread. tryAcquire( 1) // sem.available() = 9, returns true QSemaphore sem( 5) // sem.available() = 5