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/*
* Ouroboros - Copyright (C) 2016 - 2018
*
* Lockless ring buffer for incoming packets
*
* Dimitri Staessens <dimitri.staessens@ugent.be>
* Sander Vrijders <sander.vrijders@ugent.be>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1 as published by the Free Software Foundation.
*
* This 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., http://www.fsf.org/about/contact/.
*/
#define RB_HEAD __sync_fetch_and_add(rb->head, 0)
#define RB_TAIL __sync_fetch_and_add(rb->tail, 0)
void shm_rbuff_destroy(struct shm_rbuff * rb)
{
char fn[FN_MAX_CHARS];
assert(rb);
sprintf(fn, SHM_RBUFF_PREFIX "%d.%d", rb->pid, rb->port_id);
shm_rbuff_close(rb);
shm_unlink(fn);
}
int shm_rbuff_write(struct shm_rbuff * rb,
size_t idx)
{
size_t ohead;
size_t nhead;
bool was_empty = false;
assert(rb);
assert(idx < SHM_BUFFER_SIZE);
if (__sync_fetch_and_add(rb->acl, 0) != ACL_RDWR) {
if (__sync_fetch_and_add(rb->acl, 0) & ACL_FLOWDOWN)
return -EFLOWDOWN;
else if (__sync_fetch_and_add(rb->acl, 0) & ACL_RDONLY)
return -ENOTALLOC;
}
if (!shm_rbuff_free(rb))
return -EAGAIN;
if (shm_rbuff_empty(rb))
was_empty = true;
nhead = RB_HEAD;
*(rb->shm_base + nhead) = (ssize_t) idx;
do {
ohead = nhead;
nhead = (ohead + 1) & ((SHM_BUFFER_SIZE) - 1);
nhead = __sync_val_compare_and_swap(rb->head, ohead, nhead);
} while (nhead != ohead);
if (was_empty)
pthread_cond_broadcast(rb->add);
return 0;
}
ssize_t shm_rbuff_read(struct shm_rbuff * rb)
{
size_t otail;
size_t ntail;
assert(rb);
if (shm_rbuff_empty(rb))
return __sync_fetch_and_add(rb->acl, 0) & ACL_FLOWDOWN ?
-EFLOWDOWN : -EAGAIN;
ntail = RB_TAIL;
do {
otail = ntail;
ntail = (otail + 1) & ((SHM_BUFFER_SIZE) - 1);
ntail = __sync_val_compare_and_swap(rb->tail, otail, ntail);
} while (ntail != otail);
pthread_cond_broadcast(rb->del);
return *(rb->shm_base + ntail);
}
ssize_t shm_rbuff_read_b(struct shm_rbuff * rb,
const struct timespec * abstime)
{
ssize_t idx = -1;
assert(rb);
/* try a non-blocking read first */
idx = shm_rbuff_read(rb);
if (idx != -EAGAIN)
return idx;
#ifndef HAVE_ROBUST_MUTEX
pthread_mutex_lock(rb->lock);
#else
if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
pthread_mutex_consistent(rb->lock);
#endif
pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
(void *) rb->lock);
while (shm_rbuff_empty(rb) && (idx != -ETIMEDOUT)) {
if (abstime != NULL)
idx = -pthread_cond_timedwait(rb->add,
rb->lock,
abstime);
else
idx = -pthread_cond_wait(rb->add, rb->lock);
#ifdef HAVE_ROBUST_MUTEX
if (idx == -EOWNERDEAD)
pthread_mutex_consistent(rb->lock);
#endif
}
if (idx != -ETIMEDOUT) {
/* do a nonblocking read */
idx = shm_rbuff_read(rb);
assert(idx >= 0);
}
pthread_cleanup_pop(true);
return idx;
}
void shm_rbuff_set_acl(struct shm_rbuff * rb,
uint32_t flags)
{
assert(rb);
__sync_bool_compare_and_swap(rb->acl, *rb->acl, flags);
}
uint32_t shm_rbuff_get_acl(struct shm_rbuff * rb)
{
assert(rb);
return __sync_fetch_and_add(rb->acl, 0);
}
void shm_rbuff_fini(struct shm_rbuff * rb)
{
assert(rb);
if (shm_rbuff_empty(rb))
return;
#ifndef HAVE_ROBUST_MUTEX
pthread_mutex_lock(rb->lock);
#else
if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
pthread_mutex_consistent(rb->lock);
#endif
pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
(void *) rb->lock);
while (!shm_rbuff_empty(rb))
#ifndef HAVE_ROBUST_MUTEX
pthread_cond_wait(rb->del, rb->lock);
#else
if (pthread_cond_wait(rb->del, rb->lock) == EOWNERDEAD)
pthread_mutex_consistent(rb->lock);
#endif
pthread_cleanup_pop(true);
}
size_t shm_rbuff_queued(struct shm_rbuff * rb)
{
assert(rb);
return shm_rbuff_used(rb);
}
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