/* * 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->flow_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); }