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Diffstat (limited to 'include/apr_global_mutex.h')
| -rw-r--r-- | include/apr_global_mutex.h | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/include/apr_global_mutex.h b/include/apr_global_mutex.h new file mode 100644 index 0000000..e3cba23 --- /dev/null +++ b/include/apr_global_mutex.h @@ -0,0 +1,195 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef APR_GLOBAL_MUTEX_H +#define APR_GLOBAL_MUTEX_H + +/** + * @file apr_global_mutex.h + * @brief APR Global Locking Routines + */ + +#include "apr.h" +#include "apr_proc_mutex.h" /* only for apr_lockmech_e */ +#include "apr_pools.h" +#include "apr_errno.h" +#if APR_PROC_MUTEX_IS_GLOBAL +#include "apr_proc_mutex.h" +#endif +#include "apr_time.h" + +#ifdef __cplusplus +extern "C" { +#endif /* __cplusplus */ + +/** + * @defgroup APR_GlobalMutex Global Locking Routines + * @ingroup APR + * @{ + */ + +#if !APR_PROC_MUTEX_IS_GLOBAL || defined(DOXYGEN) + +/** Opaque global mutex structure. */ +typedef struct apr_global_mutex_t apr_global_mutex_t; + +/* Function definitions */ + +/** + * Create and initialize a mutex that can be used to synchronize both + * processes and threads. Note: There is considerable overhead in using + * this API if only cross-process or cross-thread mutual exclusion is + * required. See apr_proc_mutex.h and apr_thread_mutex.h for more + * specialized lock routines. + * @param mutex the memory address where the newly created mutex will be + * stored. + * @param fname A file name to use if the lock mechanism requires one. This + * argument should always be provided. The lock code itself will + * determine if it should be used. + * @param mech The mechanism to use for the interprocess lock, if any; one of + * <PRE> + * APR_LOCK_FCNTL + * APR_LOCK_FLOCK + * APR_LOCK_SYSVSEM + * APR_LOCK_POSIXSEM + * APR_LOCK_PROC_PTHREAD + * APR_LOCK_DEFAULT pick the default mechanism for the platform + * APR_LOCK_DEFAULT_TIMED pick the default timed mechanism + * </PRE> + * @param pool the pool from which to allocate the mutex. + * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports + * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_create(apr_global_mutex_t **mutex, + const char *fname, + apr_lockmech_e mech, + apr_pool_t *pool); + +/** + * Re-open a mutex in a child process. + * @param mutex The newly re-opened mutex structure. + * @param fname A file name to use if the mutex mechanism requires one. This + * argument should always be provided. The mutex code itself will + * determine if it should be used. This filename should be the + * same one that was passed to apr_global_mutex_create(). + * @param pool The pool to operate on. + * @remark This function must be called to maintain portability, even + * if the underlying lock mechanism does not require it. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_child_init( + apr_global_mutex_t **mutex, + const char *fname, + apr_pool_t *pool); + +/** + * Acquire the lock for the given mutex. If the mutex is already locked, + * the current thread will be put to sleep until the lock becomes available. + * @param mutex the mutex on which to acquire the lock. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_lock(apr_global_mutex_t *mutex); + +/** + * Attempt to acquire the lock for the given mutex. If the mutex has already + * been acquired, the call returns immediately with APR_EBUSY. Note: it + * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine + * if the return value was APR_EBUSY, for portability reasons. + * @param mutex the mutex on which to attempt the lock acquiring. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_trylock(apr_global_mutex_t *mutex); + +/** + * Attempt to acquire the lock for the given mutex until timeout expires. + * If the acquisition time outs, the call returns with APR_TIMEUP. + * @param mutex the mutex on which to attempt the lock acquiring. + * @param timeout the relative timeout (microseconds). + * @note A negative or nul timeout means immediate attempt, returning + * APR_TIMEUP without blocking if it the lock is already acquired. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_timedlock(apr_global_mutex_t *mutex, + apr_interval_time_t timeout); + +/** + * Release the lock for the given mutex. + * @param mutex the mutex from which to release the lock. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_unlock(apr_global_mutex_t *mutex); + +/** + * Destroy the mutex and free the memory associated with the lock. + * @param mutex the mutex to destroy. + */ +APR_DECLARE(apr_status_t) apr_global_mutex_destroy(apr_global_mutex_t *mutex); + +/** + * Return the name of the lockfile for the mutex, or NULL + * if the mutex doesn't use a lock file + */ +APR_DECLARE(const char *) apr_global_mutex_lockfile(apr_global_mutex_t *mutex); + +/** + * Get the mechanism of the mutex, as it relates to the actual method + * used for the underlying apr_proc_mutex_t. + * @param mutex the mutex to get the mechanism from. + */ +APR_DECLARE(apr_lockmech_e) apr_global_mutex_mech(apr_global_mutex_t *mutex); + +/** + * Get the mechanism's name of the mutex, as it relates to the actual method + * used for the underlying apr_proc_mutex_t. + * @param mutex the mutex to get the mechanism's name from. + */ +APR_DECLARE(const char *) apr_global_mutex_name(apr_global_mutex_t *mutex); + +/** + * Set mutex permissions. + */ +APR_PERMS_SET_IMPLEMENT(global_mutex); + +/** + * Get the pool used by this global_mutex. + * @return apr_pool_t the pool + */ +APR_POOL_DECLARE_ACCESSOR(global_mutex); + +#else /* APR_PROC_MUTEX_IS_GLOBAL */ + +/* Some platforms [e.g. Win32] have cross process locks that are truly + * global locks, since there isn't the concept of cross-process locks. + * Define these platforms in terms of an apr_proc_mutex_t. + */ + +#define apr_global_mutex_t apr_proc_mutex_t +#define apr_global_mutex_create apr_proc_mutex_create +#define apr_global_mutex_child_init apr_proc_mutex_child_init +#define apr_global_mutex_lock apr_proc_mutex_lock +#define apr_global_mutex_trylock apr_proc_mutex_trylock +#define apr_global_mutex_unlock apr_proc_mutex_unlock +#define apr_global_mutex_destroy apr_proc_mutex_destroy +#define apr_global_mutex_lockfile apr_proc_mutex_lockfile +#define apr_global_mutex_mech apr_proc_mutex_mech +#define apr_global_mutex_name apr_proc_mutex_name +#define apr_global_mutex_perms_set apr_proc_mutex_perms_set +#define apr_global_mutex_pool_get apr_proc_mutex_pool_get + +#endif + +/** @} */ + +#ifdef __cplusplus +} +#endif + +#endif /* ndef APR_GLOBAL_MUTEX_H */ |