diff options
Diffstat (limited to 'libpthread/sysdeps/generic/pt-rwlock-timedwrlock.c')
-rw-r--r-- | libpthread/sysdeps/generic/pt-rwlock-timedwrlock.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/libpthread/sysdeps/generic/pt-rwlock-timedwrlock.c b/libpthread/sysdeps/generic/pt-rwlock-timedwrlock.c new file mode 100644 index 00000000..04eab51f --- /dev/null +++ b/libpthread/sysdeps/generic/pt-rwlock-timedwrlock.c @@ -0,0 +1,95 @@ +/* Acquire a rwlock for writing. Generic version. + Copyright (C) 2002, 2005 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <pthread.h> +#include <assert.h> + +#include <pt-internal.h> + +/* Acquire RWLOCK for writing blocking until *ABSTIME if we cannot get + it. As a special GNU extension, if ABSTIME is NULL then the wait + shall not time out. */ +int +__pthread_rwlock_timedwrlock_internal (struct __pthread_rwlock *rwlock, + const struct timespec *abstime) +{ + struct __pthread *self; + + __pthread_spin_lock (&rwlock->__lock); + if (__pthread_spin_trylock (&rwlock->__held) == 0) + /* Successfully acquired the lock. */ + { + assert (rwlock->readerqueue == 0); + assert (rwlock->writerqueue == 0); + assert (rwlock->readers == 0); + + __pthread_spin_unlock (&rwlock->__lock); + return 0; + } + + /* The lock is busy. */ + + if (abstime && (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)) + return EINVAL; + + self = _pthread_self (); + + /* Add ourselves to the queue. */ + __pthread_enqueue (&rwlock->writerqueue, self); + __pthread_spin_unlock (&rwlock->__lock); + + /* Block the thread. */ + if (abstime) + { + error_t err; + + err = __pthread_timedblock (self, abstime); + if (err) + /* We timed out. We may need to disconnect ourself from the + waiter queue. + + FIXME: What do we do if we get a wakeup message before we + disconnect ourself? It may remain until the next time we + block. */ + { + assert (err == ETIMEDOUT); + + __pthread_spin_lock (&rwlock->__lock); + if (self->prevp) + /* Disconnect ourself. */ + __pthread_dequeue (self); + __pthread_spin_unlock (&rwlock->__lock); + + return err; + } + } + else + __pthread_block (self); + + assert (rwlock->readers == 0); + + return 0; +} + +int +pthread_rwlock_timedwrlock (struct __pthread_rwlock *rwlock, + const struct timespec *abstime) +{ + return __pthread_rwlock_timedwrlock_internal (rwlock, abstime); +} |