Condition Variables

Condition variables enable threads to be synchronised via messages. They need the <condition_variable> header. One thread acts as a sender, and the other as a receiver of the message. The receiver waits for the notification from the sender. Typical use cases for condition variables are sender-receiver or producer-consumer workflows.

A condition variable can be the sender but also the receiver of the message.

The methods of the condition variable cv

Method	Description
cv.notify_one()	Notifies a waiting thread.
cv.notify_all()	Notifies all waiting threads.
cv.wait(lock, ...)	Waits for the notification while holding a std::unique_lock.
cv.wait_for(lock, relTime, ...)	Waits for a time duration for the notification while holding a std::unique_lock.
cv.wait_until(lock, absTime, ...)	Waits until a time...