From 6fa44063041765df752cdcf81ae990e47a37681a Mon Sep 17 00:00:00 2001 From: dimitri staessens Date: Fri, 13 May 2016 19:34:29 +0200 Subject: lib: implementation of read/write locks This adds read/write locks, allowing for concurrent reads on the locked datastructure. This is needed for the fast path. --- include/ouroboros/CMakeLists.txt | 1 + include/ouroboros/rw_lock.h | 41 +++++++++++++ src/lib/CMakeLists.txt | 1 + src/lib/rw_lock.c | 125 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 168 insertions(+) create mode 100644 include/ouroboros/rw_lock.h create mode 100644 src/lib/rw_lock.c diff --git a/include/ouroboros/CMakeLists.txt b/include/ouroboros/CMakeLists.txt index a42c65fd..f1276f51 100644 --- a/include/ouroboros/CMakeLists.txt +++ b/include/ouroboros/CMakeLists.txt @@ -16,6 +16,7 @@ set(HEADER_FILES irm.h list.h logs.h + rw_lock.h shm_ap_rbuff.h shm_du_map.h sockets.h diff --git a/include/ouroboros/rw_lock.h b/include/ouroboros/rw_lock.h new file mode 100644 index 00000000..03eee605 --- /dev/null +++ b/include/ouroboros/rw_lock.h @@ -0,0 +1,41 @@ +/* + * Ouroboros - Copyright (C) 2016 + * + * Read/Write locks + * + * Dimitri Staessens + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#ifndef OUROBOROS_RWLOCK_H +#define OUROBOROS_RWLOCK_H + +#include +#include + +typedef struct rw_lock { + pthread_mutex_t lock; + pthread_mutex_t i_lock; + int i; +} rw_lock_t; + +int rw_lock_init(rw_lock_t * lock); +void rw_lock_destroy(rw_lock_t * lock); +int rw_lock_rdlock(rw_lock_t * lock); +int rw_lock_wrlock(rw_lock_t * lock); +int rw_lock_unlock(rw_lock_t * lock); + +#endif /* OUROBOROS_RWLOCK_H */ diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt index 53a7b354..72e32512 100644 --- a/src/lib/CMakeLists.txt +++ b/src/lib/CMakeLists.txt @@ -32,6 +32,7 @@ set(SOURCE_FILES ipcp.c irm.c list.c + rw_lock.c shm_ap_rbuff.c shm_du_map.c sockets.c diff --git a/src/lib/rw_lock.c b/src/lib/rw_lock.c new file mode 100644 index 00000000..cf471e60 --- /dev/null +++ b/src/lib/rw_lock.c @@ -0,0 +1,125 @@ +/* + * Ouroboros - Copyright (C) 2016 + * + * Read/Write locks + * + * Dimitri Staessens + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include + +int rw_lock_init(rw_lock_t * lock) +{ + if (lock == NULL) + return -1; + + pthread_mutex_init(&lock->lock, NULL); + pthread_mutex_init(&lock->i_lock, NULL); + lock->i = 0; + + return 0; +} + +void rw_lock_destroy(rw_lock_t * lock) +{ + if (lock == NULL) + return; + + pthread_mutex_destroy(&lock->lock); + pthread_mutex_destroy(&lock->i_lock); + lock->i = -1; +} + +int rw_lock_rdlock(rw_lock_t * lock) +{ + int ret = 0; + + if (lock == NULL) + return -1; + + pthread_mutex_lock(&lock->i_lock); + + if (lock->i < 0) { + pthread_mutex_unlock(&lock->i_lock); + return -1; + } + + if (lock->i == 0) + ret = pthread_mutex_lock(&lock->lock); + + ++(lock->i); + + pthread_mutex_unlock(&lock->i_lock); + + return ret; +} + +int rw_lock_wrlock(rw_lock_t * lock) +{ + if (lock == NULL) + return -1; + + pthread_mutex_lock(&lock->i_lock); + + if (lock->i < 0) { + pthread_mutex_unlock(&lock->i_lock); + return -1; + } + + pthread_mutex_unlock(&lock->i_lock); + + while (1) { + pthread_mutex_lock(&lock->i_lock); + + if (lock->i == 0) { + pthread_mutex_unlock(&lock->i_lock); + break; + } + + pthread_mutex_unlock(&lock->i_lock); + + sched_yield(); + } + + ++(lock->i); + + return pthread_mutex_lock(&lock->lock); +} + +int rw_lock_unlock(rw_lock_t * lock) +{ + int ret = 0; + + if (lock == NULL) + return -1; + + pthread_mutex_lock(&lock->i_lock); + + if (lock->i < 0) { + pthread_mutex_unlock(&lock->i_lock); + return -1; + } + + --(lock->i); + + if (lock->i == 0) + ret = pthread_mutex_unlock(&lock->lock); + + pthread_mutex_unlock(&lock->i_lock); + + return ret; +} -- cgit v1.2.3 From c56a4ed3b865b4b240c6f01809c935b7b86d160b Mon Sep 17 00:00:00 2001 From: dimitri staessens Date: Sat, 14 May 2016 13:26:27 +0200 Subject: lib: fixed a bug in the rw_lock Locking the main mutex should happen while the counter is locked. --- src/lib/rw_lock.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/src/lib/rw_lock.c b/src/lib/rw_lock.c index cf471e60..ba285694 100644 --- a/src/lib/rw_lock.c +++ b/src/lib/rw_lock.c @@ -70,6 +70,8 @@ int rw_lock_rdlock(rw_lock_t * lock) int rw_lock_wrlock(rw_lock_t * lock) { + int ret = 0; + if (lock == NULL) return -1; @@ -86,6 +88,8 @@ int rw_lock_wrlock(rw_lock_t * lock) pthread_mutex_lock(&lock->i_lock); if (lock->i == 0) { + ++(lock->i); + ret = pthread_mutex_lock(&lock->lock); pthread_mutex_unlock(&lock->i_lock); break; } @@ -95,9 +99,7 @@ int rw_lock_wrlock(rw_lock_t * lock) sched_yield(); } - ++(lock->i); - - return pthread_mutex_lock(&lock->lock); + return ret; } int rw_lock_unlock(rw_lock_t * lock) -- cgit v1.2.3