diff options
Diffstat (limited to 'libglusterfs/src/syncop.c')
-rw-r--r-- | libglusterfs/src/syncop.c | 150 |
1 files changed, 149 insertions, 1 deletions
diff --git a/libglusterfs/src/syncop.c b/libglusterfs/src/syncop.c index a8faa65e08a..d610a2fca03 100644 --- a/libglusterfs/src/syncop.c +++ b/libglusterfs/src/syncop.c @@ -1,5 +1,5 @@ /* - Copyright (c) 2008-2012 Red Hat, Inc. <http://www.redhat.com> + Copyright (c) 2008-2013 Red Hat, Inc. <http://www.redhat.com> This file is part of GlusterFS. This file is licensed to you under your choice of the GNU Lesser @@ -507,6 +507,154 @@ syncenv_new (size_t stacksize) } +int +synclock_init (synclock_t *lock) +{ + if (!lock) + return -1; + + pthread_cond_init (&lock->cond, 0); + lock->lock = 0; + INIT_LIST_HEAD (&lock->waitq); + + return pthread_mutex_init (&lock->guard, 0); +} + + +int +synclock_destroy (synclock_t *lock) +{ + if (!lock) + return -1; + + pthread_cond_destroy (&lock->cond); + return pthread_mutex_destroy (&lock->guard); +} + + +static int +__synclock_lock (struct synclock *lock) +{ + struct synctask *task = NULL; + + if (!lock) + return -1; + + task = synctask_get (); + + while (lock->lock) { + if (task) { + /* called within a synctask */ + list_add_tail (&task->waitq, &lock->waitq); + { + pthread_mutex_unlock (&lock->guard); + synctask_yield (task); + pthread_mutex_lock (&lock->guard); + } + list_del_init (&task->waitq); + } else { + /* called by a non-synctask */ + pthread_cond_wait (&lock->cond, &lock->guard); + } + } + + lock->lock = _gf_true; + lock->owner = task; + + return 0; +} + + +int +synclock_lock (synclock_t *lock) +{ + int ret = 0; + + pthread_mutex_lock (&lock->guard); + { + ret = __synclock_lock (lock); + } + pthread_mutex_unlock (&lock->guard); + + return ret; +} + + +int +synclock_trylock (synclock_t *lock) +{ + int ret = 0; + + errno = 0; + + pthread_mutex_lock (&lock->guard); + { + if (lock->lock) { + errno = EBUSY; + ret = -1; + goto unlock; + } + + ret = __synclock_lock (lock); + } +unlock: + pthread_mutex_unlock (&lock->guard); + + return ret; +} + + +static int +__synclock_unlock (synclock_t *lock) +{ + struct synctask *task = NULL; + struct synctask *curr = NULL; + + if (!lock) + return -1; + + curr = synctask_get (); + + if (lock->owner != curr) { + /* warn ? */ + } + + lock->lock = _gf_false; + + /* There could be both synctasks and non synctasks + waiting (or none, or either). As a mid-approach + between maintaining too many waiting counters + at one extreme and a thundering herd on unlock + at the other, call a cond_signal (which wakes + one waiter) and first synctask waiter. So at + most we have two threads waking up to grab the + just released lock. + */ + pthread_cond_signal (&lock->cond); + if (!list_empty (&lock->waitq)) { + task = list_entry (lock->waitq.next, struct synctask, waitq); + synctask_wake (task); + } + + return 0; +} + + +int +synclock_unlock (synclock_t *lock) +{ + int ret = 0; + + pthread_mutex_lock (&lock->guard); + { + ret = __synclock_unlock (lock); + } + pthread_mutex_unlock (&lock->guard); + + return ret; +} + + /* FOPS */ |