diff options
Diffstat (limited to 'libpthread/linuxthreads/rwlock.c')
| -rw-r--r-- | libpthread/linuxthreads/rwlock.c | 239 |
1 files changed, 205 insertions, 34 deletions
diff --git a/libpthread/linuxthreads/rwlock.c b/libpthread/linuxthreads/rwlock.c index 977fd88af..4a0fb1bba 100644 --- a/libpthread/linuxthreads/rwlock.c +++ b/libpthread/linuxthreads/rwlock.c @@ -1,20 +1,20 @@ /* Read-write lock implementation. - Copyright (C) 1998 Free Software Foundation, Inc. + Copyright (C) 1998, 2000 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Xavier Leroy <Xavier.Leroy@inria.fr> and Ulrich Drepper <drepper@cygnus.com>, 1998. 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 + modify it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 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. + Lesser General Public License for more details. - You should have received a copy of the GNU Library General Public + You should have received a copy of the GNU Lesser 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. */ @@ -27,6 +27,33 @@ #include "spinlock.h" #include "restart.h" +/* Function called by pthread_cancel to remove the thread from + waiting inside pthread_rwlock_timedrdlock or pthread_rwlock_timedwrlock. */ + +static int rwlock_rd_extricate_func(void *obj, pthread_descr th) +{ + pthread_rwlock_t *rwlock = obj; + int did_remove = 0; + + __pthread_lock(&rwlock->__rw_lock, NULL); + did_remove = remove_from_queue(&rwlock->__rw_read_waiting, th); + __pthread_unlock(&rwlock->__rw_lock); + + return did_remove; +} + +static int rwlock_wr_extricate_func(void *obj, pthread_descr th) +{ + pthread_rwlock_t *rwlock = obj; + int did_remove = 0; + + __pthread_lock(&rwlock->__rw_lock, NULL); + did_remove = remove_from_queue(&rwlock->__rw_write_waiting, th); + __pthread_unlock(&rwlock->__rw_lock); + + return did_remove; +} + /* * Check whether the calling thread already owns one or more read locks on the * specified lock. If so, return a pointer to the read lock info structure @@ -38,7 +65,8 @@ rwlock_is_in_list(pthread_descr self, pthread_rwlock_t *rwlock) { pthread_readlock_info *info; - for (info = self->p_readlock_list; info != NULL; info = info->pr_next) + for (info = THREAD_GETMEM (self, p_readlock_list); info != NULL; + info = info->pr_next) { if (info->pr_lock == rwlock) return info; @@ -58,10 +86,10 @@ rwlock_is_in_list(pthread_descr self, pthread_rwlock_t *rwlock) static pthread_readlock_info * rwlock_add_to_list(pthread_descr self, pthread_rwlock_t *rwlock) { - pthread_readlock_info *info = self->p_readlock_free; + pthread_readlock_info *info = THREAD_GETMEM (self, p_readlock_free); - if (info != NULL) - self->p_readlock_free = info->pr_next; + if (info != NULL) + THREAD_SETMEM (self, p_readlock_free, info->pr_next); else info = malloc(sizeof *info); @@ -70,8 +98,8 @@ rwlock_add_to_list(pthread_descr self, pthread_rwlock_t *rwlock) info->pr_lock_count = 1; info->pr_lock = rwlock; - info->pr_next = self->p_readlock_list; - self->p_readlock_list = info; + info->pr_next = THREAD_GETMEM (self, p_readlock_list); + THREAD_SETMEM (self, p_readlock_list, info); return info; } @@ -100,7 +128,7 @@ rwlock_remove_from_list(pthread_descr self, pthread_rwlock_t *rwlock) return info; } } - + return NULL; } @@ -137,7 +165,7 @@ rwlock_can_rdlock(pthread_rwlock_t *rwlock, int have_lock_already) * This function helps support brain-damaged recursive read locking * semantics required by Unix 98, while maintaining write priority. * This basically determines whether this thread already holds a read lock - * already. It returns 1 if so, otherwise it returns 0. + * already. It returns 1 if so, otherwise it returns 0. * * If the thread has any ``untracked read locks'' then it just assumes * that this lock is among them, just to be safe, and returns 1. @@ -161,11 +189,12 @@ rwlock_have_already(pthread_descr *pself, pthread_rwlock_t *rwlock, if (rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_WRITER_NP) { if (!self) - self = thread_self(); + *pself = self = thread_self(); existing = rwlock_is_in_list(self, rwlock); - if (existing != NULL || self->p_untracked_readlock_count > 0) + if (existing != NULL + || THREAD_GETMEM (self, p_untracked_readlock_count) > 0) have_lock_already = 1; else { @@ -177,7 +206,6 @@ rwlock_have_already(pthread_descr *pself, pthread_rwlock_t *rwlock, *pout_of_mem = out_of_mem; *pexisting = existing; - *pself = self; return have_lock_already; } @@ -207,6 +235,7 @@ pthread_rwlock_init (pthread_rwlock_t *rwlock, } + int pthread_rwlock_destroy (pthread_rwlock_t *rwlock) { @@ -224,6 +253,7 @@ pthread_rwlock_destroy (pthread_rwlock_t *rwlock) return 0; } + int pthread_rwlock_rdlock (pthread_rwlock_t *rwlock) { @@ -232,13 +262,13 @@ pthread_rwlock_rdlock (pthread_rwlock_t *rwlock) int out_of_mem, have_lock_already; have_lock_already = rwlock_have_already(&self, rwlock, - &existing, &out_of_mem); + &existing, &out_of_mem); + + if (self == NULL) + self = thread_self (); for (;;) { - if (self == NULL) - self = thread_self (); - __pthread_lock (&rwlock->__rw_lock, self); if (rwlock_can_rdlock(rwlock, have_lock_already)) @@ -255,14 +285,86 @@ pthread_rwlock_rdlock (pthread_rwlock_t *rwlock) if (have_lock_already || out_of_mem) { if (existing != NULL) - existing->pr_lock_count++; + ++existing->pr_lock_count; else - self->p_untracked_readlock_count++; + ++self->p_untracked_readlock_count; } - + return 0; } + +int +pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock, + const struct timespec *abstime) +{ + pthread_descr self = NULL; + pthread_readlock_info *existing; + int out_of_mem, have_lock_already; + pthread_extricate_if extr; + + if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) + return EINVAL; + + have_lock_already = rwlock_have_already(&self, rwlock, + &existing, &out_of_mem); + + if (self == NULL) + self = thread_self (); + + /* Set up extrication interface */ + extr.pu_object = rwlock; + extr.pu_extricate_func = rwlock_rd_extricate_func; + + /* Register extrication interface */ + __pthread_set_own_extricate_if (self, &extr); + + for (;;) + { + __pthread_lock (&rwlock->__rw_lock, self); + + if (rwlock_can_rdlock(rwlock, have_lock_already)) + break; + + enqueue (&rwlock->__rw_read_waiting, self); + __pthread_unlock (&rwlock->__rw_lock); + /* This is not a cancellation point */ + if (timedsuspend (self, abstime) == 0) + { + int was_on_queue; + + __pthread_lock (&rwlock->__rw_lock, self); + was_on_queue = remove_from_queue (&rwlock->__rw_read_waiting, self); + __pthread_unlock (&rwlock->__rw_lock); + + if (was_on_queue) + { + __pthread_set_own_extricate_if (self, 0); + return ETIMEDOUT; + } + + /* Eat the outstanding restart() from the signaller */ + suspend (self); + } + } + + __pthread_set_own_extricate_if (self, 0); + + ++rwlock->__rw_readers; + __pthread_unlock (&rwlock->__rw_lock); + + if (have_lock_already || out_of_mem) + { + if (existing != NULL) + ++existing->pr_lock_count; + else + ++self->p_untracked_readlock_count; + } + + return 0; +} + + int pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock) { @@ -277,7 +379,7 @@ pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock) __pthread_lock (&rwlock->__rw_lock, self); /* 0 is passed to here instead of have_lock_already. - This is to meet Single Unix Spec requirements: + This is to meet Single Unix Spec requirements: if writers are waiting, pthread_rwlock_tryrdlock does not acquire a read lock, even if the caller has one or more read locks already. */ @@ -295,16 +397,17 @@ pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock) if (have_lock_already || out_of_mem) { if (existing != NULL) - existing->pr_lock_count++; + ++existing->pr_lock_count; else - self->p_untracked_readlock_count++; + ++self->p_untracked_readlock_count; } } - + return retval; } + int pthread_rwlock_wrlock (pthread_rwlock_t *rwlock) { @@ -328,6 +431,64 @@ pthread_rwlock_wrlock (pthread_rwlock_t *rwlock) } + +int +pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock, + const struct timespec *abstime) +{ + pthread_descr self; + pthread_extricate_if extr; + + if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) + return EINVAL; + + self = thread_self (); + + /* Set up extrication interface */ + extr.pu_object = rwlock; + extr.pu_extricate_func = rwlock_wr_extricate_func; + + /* Register extrication interface */ + __pthread_set_own_extricate_if (self, &extr); + + while(1) + { + __pthread_lock (&rwlock->__rw_lock, self); + + if (rwlock->__rw_readers == 0 && rwlock->__rw_writer == NULL) + { + rwlock->__rw_writer = self; + __pthread_set_own_extricate_if (self, 0); + __pthread_unlock (&rwlock->__rw_lock); + return 0; + } + + /* Suspend ourselves, then try again */ + enqueue (&rwlock->__rw_write_waiting, self); + __pthread_unlock (&rwlock->__rw_lock); + /* This is not a cancellation point */ + if (timedsuspend (self, abstime) == 0) + { + int was_on_queue; + + __pthread_lock (&rwlock->__rw_lock, self); + was_on_queue = remove_from_queue (&rwlock->__rw_write_waiting, self); + __pthread_unlock (&rwlock->__rw_lock); + + if (was_on_queue) + { + __pthread_set_own_extricate_if (self, 0); + return ETIMEDOUT; + } + + /* Eat the outstanding restart() from the signaller */ + suspend (self); + } + } +} + + + int pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock) { @@ -345,6 +506,7 @@ pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock) } + int pthread_rwlock_unlock (pthread_rwlock_t *rwlock) { @@ -362,8 +524,9 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock) } rwlock->__rw_writer = NULL; - if (rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP - || (th = dequeue (&rwlock->__rw_write_waiting)) == NULL) + if ((rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP + && !queue_is_empty(&rwlock->__rw_read_waiting)) + || (th = dequeue(&rwlock->__rw_write_waiting)) == NULL) { /* Restart all waiting readers. */ torestart = rwlock->__rw_read_waiting; @@ -410,14 +573,15 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock) { if (victim->pr_lock_count == 0) { - victim->pr_next = self->p_readlock_free; - self->p_readlock_free = victim; + victim->pr_next = THREAD_GETMEM (self, p_readlock_free); + THREAD_SETMEM (self, p_readlock_free, victim); } } else { - if (self->p_untracked_readlock_count > 0) - self->p_untracked_readlock_count--; + int val = THREAD_GETMEM (self, p_untracked_readlock_count); + if (val > 0) + THREAD_SETMEM (self, p_untracked_readlock_count, val - 1); } } } @@ -427,11 +591,12 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock) + int pthread_rwlockattr_init (pthread_rwlockattr_t *attr) { attr->__lockkind = 0; - attr->__pshared = 0; + attr->__pshared = PTHREAD_PROCESS_PRIVATE; return 0; } @@ -444,6 +609,7 @@ pthread_rwlockattr_destroy (pthread_rwlockattr_t *attr) } + int pthread_rwlockattr_getpshared (const pthread_rwlockattr_t *attr, int *pshared) { @@ -458,6 +624,10 @@ pthread_rwlockattr_setpshared (pthread_rwlockattr_t *attr, int pshared) if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED) return EINVAL; + /* For now it is not possible to shared a conditional variable. */ + if (pshared != PTHREAD_PROCESS_PRIVATE) + return ENOSYS; + attr->__pshared = pshared; return 0; @@ -477,6 +647,7 @@ pthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr, int pref) { if (pref != PTHREAD_RWLOCK_PREFER_READER_NP && pref != PTHREAD_RWLOCK_PREFER_WRITER_NP + && pref != PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP && pref != PTHREAD_RWLOCK_DEFAULT_NP) return EINVAL; |