Without putting the receiver to sleep, force processes that try to wait
on the semaphore to block. Answer whether this was the case even before.
notify
Resume one of the processes that were waiting on the semaphore if
there were any. Do not leave a signal on the semaphore if no
process is waiting.
notifyAll
Resume all the processes that were waiting on the semaphore if there
were any. Do not leave a signal on the semaphore if no process is
waiting.
signal
Signal the receiver, resuming a waiting process' if there is one
wait
Wait for the receiver to be signalled, suspending the executing process
if it is not yet
are
waitAfterSignalling: aSemaphore
Signal aSemaphore then, atomically, wait for the receiver to be
signalled, suspending the executing process if it is not yet. This
is needed to avoid race conditions when the #notify and #notifyAll
are used before waiting on receiver: otherwise, if a process sends
any of the two between the time aSemaphore is signaled and the time
the process starts waiting on the receiver, the notification is lost.