void
flockfile(FILE * fp)
{
int idx = file_idx(fp);
struct file_lock *p;
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/* Check if the static array has not been initialised: */
if (!init_done) {
/* Initialise the global array: */
memset(flh,0,sizeof(flh));
/* Flag the initialisation as complete: */
init_done = 1;
}
/* Get a pointer to any existing lock for the file: */
if ((p = find_lock(idx, fp)) == NULL) {
/*
* The file is not locked, so this thread can
* grab the lock:
*/
p = do_lock(idx, fp);
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/*
* The file is already locked, so check if the
* running thread is the owner:
*/
} else if (p->owner == _thread_run) {
/*
* The running thread is already the
* owner, so increment the count of
* the number of times it has locked
* the file:
*/
p->count++;
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
} else {
/*
* The file is locked for another thread.
* Append this thread to the queue of
* threads waiting on the lock.
*/
TAILQ_INSERT_TAIL(&p->l_head,_thread_run,qe);
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/* Wait on the FILE lock: */
_thread_kern_sched_state(PS_FILE_WAIT, "", 0);
}
}
int
(ftrylockfile)(FILE * fp)
{
int ret = -1;
int idx = file_idx(fp);
struct file_lock *p;
/* Lock the hash table: */
_spinlock(&hash_lock);
/* Get a pointer to any existing lock for the file: */
if ((p = find_lock(idx, fp)) == NULL) {
/*
* The file is not locked, so this thread can
* grab the lock:
*/
p = do_lock(idx, fp);
/*
* The file is already locked, so check if the
* running thread is the owner:
*/
} else if (p->owner == pthread_self()) {
/*
* The running thread is already the
* owner, so increment the count of
* the number of times it has locked
* the file:
*/
p->count++;
} else {
/*
* The file is locked for another thread,
* so this try fails.
*/
p = NULL;
}
/* Unlock the hash table: */
_spinunlock(&hash_lock);
/* Check if the lock was obtained: */
if (p != NULL)
/* Return success: */
ret = 0;
return (ret);
}
void
(flockfile)(FILE * fp)
{
int idx = file_idx(fp);
struct file_lock *p;
pthread_t self = pthread_self();
/* Lock the hash table: */
_spinlock(&hash_lock);
/* Get a pointer to any existing lock for the file: */
if ((p = find_lock(idx, fp)) == NULL) {
/*
* The file is not locked, so this thread can
* grab the lock:
*/
do_lock(idx, fp);
/*
* The file is already locked, so check if the
* running thread is the owner:
*/
} else if (p->owner == self) {
/*
* The running thread is already the
* owner, so increment the count of
* the number of times it has locked
* the file:
*/
p->count++;
} else {
/*
* The file is locked for another thread.
* Append this thread to the queue of
* threads waiting on the lock.
*/
TAILQ_INSERT_TAIL(&p->lockers,self,waiting);
while (p->owner != self) {
__thrsleep(self, 0 | _USING_TICKETS, NULL,
&hash_lock.ticket, NULL);
_spinlock(&hash_lock);
}
}
/* Unlock the hash table: */
_spinunlock(&hash_lock);
}
void
(funlockfile)(FILE * fp)
{
int idx = file_idx(fp);
struct file_lock *p;
/* Lock the hash table: */
_spinlock(&hash_lock);
/*
* Get a pointer to the lock for the file and check that
* the running thread is the one with the lock:
*/
if ((p = find_lock(idx, fp)) != NULL && p->owner == pthread_self()) {
/*
* Check if this thread has locked the FILE
* more than once:
*/
if (--p->count == 0) {
/* Get the new owner of the lock: */
if ((p->owner = TAILQ_FIRST(&p->lockers)) != NULL) {
/* Pop the thread off the queue: */
TAILQ_REMOVE(&p->lockers,p->owner,waiting);
/*
* This is the first lock for the new
* owner:
*/
p->count = 1;
__thrwakeup(p->owner, 1);
}
}
}
/* Unlock the hash table: */
_spinunlock(&hash_lock);
}
void
funlockfile(FILE * fp)
{
int idx = file_idx(fp);
struct file_lock *p;
/*
* Defer signals to protect the scheduling queues from
* access by the signal handler:
*/
_thread_kern_sig_defer();
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/*
* Get a pointer to the lock for the file and check that
* the running thread is the one with the lock:
*/
if ((p = find_lock(idx, fp)) != NULL &&
p->owner == _thread_run) {
/*
* Check if this thread has locked the FILE
* more than once:
*/
if (p->count > 1)
/*
* Decrement the count of the number of
* times the running thread has locked this
* file:
*/
p->count--;
else {
/*
* The running thread will release the
* lock now:
*/
p->count = 0;
/* Get the new owner of the lock: */
if ((p->owner = TAILQ_FIRST(&p->l_head)) != NULL) {
/* Pop the thread off the queue: */
TAILQ_REMOVE(&p->l_head,p->owner,qe);
/*
* This is the first lock for the new
* owner:
*/
p->count = 1;
/* Allow the new owner to run: */
PTHREAD_NEW_STATE(p->owner,PS_RUNNING);
}
}
}
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/*
* Undefer and handle pending signals, yielding if
* necessary:
*/
_thread_kern_sig_undefer();
}