Atomic lock file creation

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LEARN ABOUT FREEBSD

pthread_spin_trylock

PTHREAD_SPIN_LOCK(3)					   BSD Library Functions Manual 				      PTHREAD_SPIN_LOCK(3)

NAME

     pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock -- lock or unlock 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);

     int
     pthread_spin_unlock(pthread_spinlock_t *lock);

DESCRIPTION

     The pthread_spin_lock() function will acquire lock if it is not currently owned by another thread.  If the lock cannot be acquired immedi-
     ately, it will spin attempting to acquire the lock (it will not sleep) until it becomes available.

     The pthread_spin_trylock() function is the same as pthread_spin_lock() except that if it cannot acquire lock immediately it will return with
     an error.

     The pthread_spin_unlock() function will release lock, which must have been previously locked by a call to pthread_spin_lock() or
     pthread_spin_trylock().

RETURN VALUES

     If successful, all these functions will return zero.  Otherwise, an error number will be returned to indicate the error.

     None of these functions will return EINTR.

ERRORS

     The pthread_spin_lock(), pthread_spin_trylock() and pthread_spin_unlock() functions will fail if:

     [EINVAL]		The value specified by lock is invalid or is not initialized.

     The pthread_spin_lock() function may fail if:

     [EDEADLK]		The calling thread already owns the lock.

     The pthread_spin_trylock() function will fail if:

     [EBUSY]		Another thread currently holds lock.

     The pthread_spin_unlock() function may fail if:

     [EPERM]		The calling thread does not own lock.

SEE ALSO

     pthread_spin_destroy(3), pthread_spin_init(3)

HISTORY

     The pthread_spin_lock(), pthread_spin_trylock() and pthread_spin_unlock() functions first appeared in N:M Threading Library (libkse, -lkse)
     in FreeBSD 5.2, and in 1:1 Threading Library (libthr, -lthr) in FreeBSD 5.3.

BUGS

     The implementation of pthread_spin_lock(), pthread_spin_trylock() and pthread_spin_unlock() is expected to conform to IEEE Std 1003.2
     (``POSIX.2'').

BSD
								 January 22, 2004							       BSD

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