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1.146.3 Semaphore: builtins

lock
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.