pthread_spin_trylock(3) - NetBSD Manual Pages

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PTHREAD_SPIN_LOCK(3)    NetBSD Library Functions Manual   PTHREAD_SPIN_LOCK(3)


NAME

     pthread_spin_lock, pthread_spin_trylock -- acquire a spin lock


LIBRARY

     POSIX Threads Library (libpthread, -lpthread)


SYNOPSIS

     #include <pthread.h>

     int
     pthread_spin_lock(pthread_spinlock_t *lock);

     int
     pthread_spin_trylock(pthread_spinlock_t *lock);


DESCRIPTION

     The pthread_spin_lock() function acquires a spin lock on lock provided
     that lock is not presently held.  If the lock cannot be immediately
     acquired, the calling thread repeatedly retries until it can acquire the
     lock.

     The pthread_spin_trylock() function performs the same action, but does
     not block if the lock cannot be immediately obtained (i.e., the lock is
     held).


RETURN VALUES

     If successful, the pthread_spin_lock() and pthread_spin_trylock() func-
     tions will return zero.  Otherwise an error number will be returned to
     indicate the error.


ERRORS

     The pthread_spin_trylock() function shall fail if:

     [EBUSY]            The lock could not be acquired because a writer holds
                        the lock or was blocked on it.

     The pthread_spin_lock() function may fail if:

     [EDEADLK]          The current thread already owns lock for writing.

     The pthread_spin_lock() and pthread_spin_trylock() functions may fail if:

     [EINVAL]           The value specified by lock is invalid.


SEE ALSO

     pthread_spin_destroy(3), pthread_spin_init(3), pthread_spin_unlock(3)


STANDARDS

     pthread_spin_lock() and pthread_spin_trylock() conform to IEEE Std
     1003.1-2001 (``POSIX.1'').


CAVEATS

     Applications using spinlocks are vulnerable to the effects of priority
     inversion.  Applications using real-time threads (SCHED_FIFO, SCHED_RR)
     should not use these interfaces.  Outside carefully controlled environ-
     ments, priority inversion with spinlocks can lead to system deadlock.
     Mutexes are preferable in nearly every possible use case.

NetBSD 5.2                       May 26, 2008                       NetBSD 5.2