| /* $Id$ */ |
| /* |
| * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com) |
| * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org> |
| * |
| * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| /* |
| * Note: |
| * |
| * DO NOT BUILD THIS FILE DIRECTLY. THIS FILE WILL BE INCLUDED BY os_core_*.c |
| * WHEN MACRO PJ_EMULATE_RWMUTEX IS SET. |
| */ |
| |
| /* |
| * os_rwmutex.c: |
| * |
| * Implementation of Read-Write mutex for platforms that lack it (e.g. |
| * Win32, RTEMS). |
| */ |
| |
| |
| struct pj_rwmutex_t |
| { |
| pj_mutex_t *read_lock; |
| /* write_lock must use semaphore, because write_lock may be released |
| * by thread other than the thread that acquire the write_lock in the |
| * first place. |
| */ |
| pj_sem_t *write_lock; |
| pj_int32_t reader_count; |
| }; |
| |
| /* |
| * Create reader/writer mutex. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_create(pj_pool_t *pool, const char *name, |
| pj_rwmutex_t **p_mutex) |
| { |
| pj_status_t status; |
| pj_rwmutex_t *rwmutex; |
| |
| PJ_ASSERT_RETURN(pool && p_mutex, PJ_EINVAL); |
| |
| *p_mutex = NULL; |
| rwmutex = PJ_POOL_ALLOC_T(pool, pj_rwmutex_t); |
| |
| status = pj_mutex_create_simple(pool, name, &rwmutex ->read_lock); |
| if (status != PJ_SUCCESS) |
| return status; |
| |
| status = pj_sem_create(pool, name, 1, 1, &rwmutex->write_lock); |
| if (status != PJ_SUCCESS) { |
| pj_mutex_destroy(rwmutex->read_lock); |
| return status; |
| } |
| |
| rwmutex->reader_count = 0; |
| *p_mutex = rwmutex; |
| return PJ_SUCCESS; |
| } |
| |
| /* |
| * Lock the mutex for reading. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_lock_read(pj_rwmutex_t *mutex) |
| { |
| pj_status_t status; |
| |
| PJ_ASSERT_RETURN(mutex, PJ_EINVAL); |
| |
| status = pj_mutex_lock(mutex->read_lock); |
| if (status != PJ_SUCCESS) { |
| pj_assert(!"This pretty much is unexpected"); |
| return status; |
| } |
| |
| mutex->reader_count++; |
| |
| pj_assert(mutex->reader_count < 0x7FFFFFF0L); |
| |
| if (mutex->reader_count == 1) |
| pj_sem_wait(mutex->write_lock); |
| |
| status = pj_mutex_unlock(mutex->read_lock); |
| return status; |
| } |
| |
| /* |
| * Lock the mutex for writing. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_lock_write(pj_rwmutex_t *mutex) |
| { |
| PJ_ASSERT_RETURN(mutex, PJ_EINVAL); |
| return pj_sem_wait(mutex->write_lock); |
| } |
| |
| /* |
| * Release read lock. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_unlock_read(pj_rwmutex_t *mutex) |
| { |
| pj_status_t status; |
| |
| PJ_ASSERT_RETURN(mutex, PJ_EINVAL); |
| |
| status = pj_mutex_lock(mutex->read_lock); |
| if (status != PJ_SUCCESS) { |
| pj_assert(!"This pretty much is unexpected"); |
| return status; |
| } |
| |
| pj_assert(mutex->reader_count >= 1); |
| |
| --mutex->reader_count; |
| if (mutex->reader_count == 0) |
| pj_sem_post(mutex->write_lock); |
| |
| status = pj_mutex_unlock(mutex->read_lock); |
| return status; |
| } |
| |
| /* |
| * Release write lock. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_unlock_write(pj_rwmutex_t *mutex) |
| { |
| PJ_ASSERT_RETURN(mutex, PJ_EINVAL); |
| pj_assert(mutex->reader_count <= 1); |
| return pj_sem_post(mutex->write_lock); |
| } |
| |
| |
| /* |
| * Destroy reader/writer mutex. |
| * |
| */ |
| PJ_DEF(pj_status_t) pj_rwmutex_destroy(pj_rwmutex_t *mutex) |
| { |
| PJ_ASSERT_RETURN(mutex, PJ_EINVAL); |
| pj_mutex_destroy(mutex->read_lock); |
| pj_sem_destroy(mutex->write_lock); |
| return PJ_SUCCESS; |
| } |
| |