The type of condition variables.

create () creates and returns a new condition variable. This condition variable should be associated (in the programmer's mind) with a certain mutex m and with a certain property P of the data structure that is protected by the mutex m.

broadcast c wakes up all threads waiting on the condition variable c. If there are none, this call has no effect.

It is recommended to call broadcast c inside a critical section, that is, while the mutex m associated with c is locked.

signal c wakes up one of the threads waiting on the condition variable c, if there is one. If there is none, this call has no effect.

It is recommended to call signal c inside a critical section, that is, while the mutex m associated with c is locked.

The call wait c m is permitted only if m is the mutex associated with the condition variable c, and only if m is currently locked. This call atomically unlocks the mutex m and suspends he current thread on the condition variable c. This thread can later be woken up after the condition c has been signaled via signal or broadcast; however, it can also be woken up for no reason. The mutex m is locked again before wait returns. One cannot assume that the property P associated with the condition variable c holds when wait returns; one must explicitly test whether P holds after calling wait.