/* 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_PROC_MUTEX_H #define APR_PROC_MUTEX_H /** * @file apr_proc_mutex.h * @brief APR Process Locking Routines */ #include "apr.h" #include "apr_pools.h" #include "apr_errno.h" #ifdef __cplusplus extern "C" { #endif /* __cplusplus */ /** * @defgroup apr_proc_mutex Process Locking Routines * @ingroup APR * @{ */ /** * Enumerated potential types for APR process locking methods * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. */ typedef enum { APR_LOCK_FCNTL, /**< fcntl() */ APR_LOCK_FLOCK, /**< flock() */ APR_LOCK_SYSVSEM, /**< System V Semaphores */ APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */ APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */ APR_LOCK_DEFAULT /**< Use the default process lock */ } apr_lockmech_e; /** Opaque structure representing a process mutex. */ typedef struct apr_proc_mutex_t apr_proc_mutex_t; /* Function definitions */ /** * Create and initialize a mutex that can be used to synchronize processes. * @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 * </PRE> * @param pool the pool from which to allocate the mutex. * @see apr_lockmech_e * @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_proc_mutex_create(apr_proc_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_proc_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_proc_mutex_child_init(apr_proc_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_proc_mutex_lock(apr_proc_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_proc_mutex_trylock(apr_proc_mutex_t *mutex); /** * Release the lock for the given mutex. * @param mutex the mutex from which to release the lock. */ APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_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_proc_mutex_destroy(apr_proc_mutex_t *mutex); /** * Destroy the mutex and free the memory associated with the lock. * @param mutex the mutex to destroy. * @note This function is generally used to kill a cleanup on an already * created mutex */ APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *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_proc_mutex_lockfile(apr_proc_mutex_t *mutex); /** * Display the name of the mutex, as it relates to the actual method used. * This matches the valid options for Apache's AcceptMutex directive * @param mutex the name of the mutex */ APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex); /** * Display the name of the default mutex: APR_LOCK_DEFAULT */ APR_DECLARE(const char *) apr_proc_mutex_defname(void); /** * Get the pool used by this proc_mutex. * @return apr_pool_t the pool */ APR_POOL_DECLARE_ACCESSOR(proc_mutex); /** @} */ #ifdef __cplusplus } #endif #endif /* ! APR_PROC_MUTEX_H */