name : apr_global_mutex.h /* 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 */