PTHREAD_SPIN(3) | Library Functions Manual | PTHREAD_SPIN(3) |
pthread_spin
, pthread_spin_init
,
pthread_spin_destroy
,
pthread_spin_lock
,
pthread_spin_trylock
,
pthread_spin_unlock
—
#include <pthread.h>
int
pthread_spin_init
(pthread_spinlock_t
*lock, int
pshared);
int
pthread_spin_destroy
(pthread_spinlock_t
*lock);
int
pthread_spin_lock
(pthread_spinlock_t
*lock);
int
pthread_spin_trylock
(pthread_spinlock_t
*lock);
int
pthread_spin_unlock
(pthread_spinlock_t
*lock);
pthread_spin_init
() function is used to initialize a
spin lock. In the NetBSD implementation the
pshared parameter is currently unused and all spin locks
exhibit the PTHREAD_PROCESS_SHARED
property, implying
that all spin locks may be accessed by threads of multiple processes. The
results of calling pthread_spin_init
() with an already
initialized lock are undefined.
The pthread_spin_destroy
() function is
used to destroy a spin lock previously created with
pthread_spin_init
(). It is undefined what happens if
the function is called when a thread holds the lock, or if the function is
called with an uninitialized spin lock.
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. Undefined behavior may follow if the calling thread holds
the lock at the time the call is made.
The pthread_spin_trylock
() function
performs the same locking action, but does not block if the lock cannot be
immediately obtained; if the lock is held, the call fails.
The pthread_spin_unlock
() function is used
to release the read/write lock previously obtained by
pthread_spin_lock
() or
pthread_spin_trylock
(). The results are undefined if
the lock is not held by the calling thread.
pthread_spin_init
() function shall fail if:
ENOMEM
]The pthread_spin_init
() function may fail
if:
EINVAL
]NULL
or the pshared parameter was neither
PTHREAD_PROCESS_SHARED
nor
PTHREAD_PROCESS_PRIVATE
.The pthread_spin_destroy
() function may
fail if:
EBUSY
]EINVAL
]The pthread_spin_trylock
() function shall
fail if:
EBUSY
]The pthread_spin_lock
() function may fail
if:
EDEADLK
]The pthread_spin_lock
() and
pthread_spin_trylock
() functions may fail if:
EINVAL
]The pthread_spin_unlock
() function may
fail if:
EINVAL
]SCHED_FIFO
), (SCHED_RR
)
should not use these interfaces. Outside carefully controlled environments,
priority inversion with spin locks can lead to system deadlock. Mutexes are
preferable in nearly every possible use case.
July 8, 2010 | NetBSD 9.0 |