Mutex: Difference between revisions

=={{header|J}}==

J904 introduces mutexes.

Note: currently J mutexes do not have a meaningful display representation.

<lang J> name=. 10 T. 0 NB. create an exclusive mutex

name=. 10 T. 1 NB. create a shared (aka "recursive") mutex

failed=. 11 T. mutex NB. take an exclusive lock on a mutex (waiting forever if necessary)

failed=. 11 T. mutex;seconds NB. try to take an exclusive lock on a mutex but may time out

NB. failed is 0 if lock was taken, 1 if lock was not taken

13 T. mutex NB. release lock on mutex</lang>

Recursive mutexes may be locked multiple times -- successive locks increase a counter. When unlocked as many times as previously locked, the mutex is released.

Exclusive mutexes will suspend (waiting "forever" if necessary) if the lock was already taken.