SYS$WFLAND (OpenVMS) SYS$WFLAND (OpenVMS)
NAME
semop - perform semaphore operations
SYS$WFLAND - Wait for logical AND of event flags
EXPLAINATION
The Digital UNIX semop system call is similar to the OpenVMS SYS$WFLAND
system service in that they both cause a process to wait while waiting
on multiple process synchronization operations. The semop function can
be called with the nops (third) argument set to the number of sema‐
phores you wish to wait for. The semop array would then specify an
array of sembuf structures indicating the semaphore numbers in the sem‐
aphore set and the operation that is to be performed on the semaphore.
To potentially cause a wait, a negative sem_op value is implied. The
semop function will block until all semaphore operations specified in
the array can be performed atomically. If all operations are decre‐
ments on binary semaphores, the result is that all semaphores must be
1. This is very similar to the logical and operation except that the
semaphores get set to zero as a side effect.
RELATED INFORMATION
Digital UNIX Functions:
semop(2), semget(2), semctl(2) delim off
SYS$WFLAND (OpenVMS)
