00001 /* Licensed to the Apache Software Foundation (ASF) under one or more 00002 * contributor license agreements. See the NOTICE file distributed with 00003 * this work for additional information regarding copyright ownership. 00004 * The ASF licenses this file to You under the Apache License, Version 2.0 00005 * (the "License"); you may not use this file except in compliance with 00006 * the License. You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #ifndef APR_PROC_MUTEX_H 00018 #define APR_PROC_MUTEX_H 00019 00020 /** 00021 * @file apr_proc_mutex.h 00022 * @brief APR Process Locking Routines 00023 */ 00024 00025 #include "apr.h" 00026 #include "apr_pools.h" 00027 #include "apr_errno.h" 00028 00029 #ifdef __cplusplus 00030 extern "C" { 00031 #endif /* __cplusplus */ 00032 00033 /** 00034 * @defgroup apr_proc_mutex Process Locking Routines 00035 * @ingroup APR 00036 * @{ 00037 */ 00038 00039 /** 00040 * Enumerated potential types for APR process locking methods 00041 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 00042 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 00043 */ 00044 typedef enum { 00045 APR_LOCK_FCNTL, /**< fcntl() */ 00046 APR_LOCK_FLOCK, /**< flock() */ 00047 APR_LOCK_SYSVSEM, /**< System V Semaphores */ 00048 APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */ 00049 APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */ 00050 APR_LOCK_DEFAULT /**< Use the default process lock */ 00051 } apr_lockmech_e; 00052 00053 /** Opaque structure representing a process mutex. */ 00054 typedef struct apr_proc_mutex_t apr_proc_mutex_t; 00055 00056 /* Function definitions */ 00057 00058 /** 00059 * Create and initialize a mutex that can be used to synchronize processes. 00060 * @param mutex the memory address where the newly created mutex will be 00061 * stored. 00062 * @param fname A file name to use if the lock mechanism requires one. This 00063 * argument should always be provided. The lock code itself will 00064 * determine if it should be used. 00065 * @param mech The mechanism to use for the interprocess lock, if any; one of 00066 * <PRE> 00067 * APR_LOCK_FCNTL 00068 * APR_LOCK_FLOCK 00069 * APR_LOCK_SYSVSEM 00070 * APR_LOCK_POSIXSEM 00071 * APR_LOCK_PROC_PTHREAD 00072 * APR_LOCK_DEFAULT pick the default mechanism for the platform 00073 * </PRE> 00074 * @param pool the pool from which to allocate the mutex. 00075 * @see apr_lockmech_e 00076 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 00077 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 00078 */ 00079 APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex, 00080 const char *fname, 00081 apr_lockmech_e mech, 00082 apr_pool_t *pool); 00083 00084 /** 00085 * Re-open a mutex in a child process. 00086 * @param mutex The newly re-opened mutex structure. 00087 * @param fname A file name to use if the mutex mechanism requires one. This 00088 * argument should always be provided. The mutex code itself will 00089 * determine if it should be used. This filename should be the 00090 * same one that was passed to apr_proc_mutex_create(). 00091 * @param pool The pool to operate on. 00092 * @remark This function must be called to maintain portability, even 00093 * if the underlying lock mechanism does not require it. 00094 */ 00095 APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex, 00096 const char *fname, 00097 apr_pool_t *pool); 00098 00099 /** 00100 * Acquire the lock for the given mutex. If the mutex is already locked, 00101 * the current thread will be put to sleep until the lock becomes available. 00102 * @param mutex the mutex on which to acquire the lock. 00103 */ 00104 APR_DECLARE(apr_status_t) apr_proc_mutex_lock(apr_proc_mutex_t *mutex); 00105 00106 /** 00107 * Attempt to acquire the lock for the given mutex. If the mutex has already 00108 * been acquired, the call returns immediately with APR_EBUSY. Note: it 00109 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 00110 * if the return value was APR_EBUSY, for portability reasons. 00111 * @param mutex the mutex on which to attempt the lock acquiring. 00112 */ 00113 APR_DECLARE(apr_status_t) apr_proc_mutex_trylock(apr_proc_mutex_t *mutex); 00114 00115 /** 00116 * Release the lock for the given mutex. 00117 * @param mutex the mutex from which to release the lock. 00118 */ 00119 APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_mutex_t *mutex); 00120 00121 /** 00122 * Destroy the mutex and free the memory associated with the lock. 00123 * @param mutex the mutex to destroy. 00124 */ 00125 APR_DECLARE(apr_status_t) apr_proc_mutex_destroy(apr_proc_mutex_t *mutex); 00126 00127 /** 00128 * Destroy the mutex and free the memory associated with the lock. 00129 * @param mutex the mutex to destroy. 00130 * @note This function is generally used to kill a cleanup on an already 00131 * created mutex 00132 */ 00133 APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex); 00134 00135 /** 00136 * Return the name of the lockfile for the mutex, or NULL 00137 * if the mutex doesn't use a lock file 00138 */ 00139 00140 APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex); 00141 00142 /** 00143 * Display the name of the mutex, as it relates to the actual method used. 00144 * This matches the valid options for Apache's AcceptMutex directive 00145 * @param mutex the name of the mutex 00146 */ 00147 APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex); 00148 00149 /** 00150 * Display the name of the default mutex: APR_LOCK_DEFAULT 00151 */ 00152 APR_DECLARE(const char *) apr_proc_mutex_defname(void); 00153 00154 /** 00155 * Get the pool used by this proc_mutex. 00156 * @return apr_pool_t the pool 00157 */ 00158 APR_POOL_DECLARE_ACCESSOR(proc_mutex); 00159 00160 /** @} */ 00161 00162 #ifdef __cplusplus 00163 } 00164 #endif 00165 00166 #endif /* ! APR_PROC_MUTEX_H */