1 /* Licensed to the Apache Software Foundation (ASF) under one or more 2 * contributor license agreements. See the NOTICE file distributed with 3 * this work for additional information regarding copyright ownership. 4 * The ASF licenses this file to You under the Apache License, Version 2.0 5 * (the "License"); you may not use this file except in compliance with 6 * the License. You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef APR_THREAD_MUTEX_H 18 #define APR_THREAD_MUTEX_H 19 20 /** 21 * @file apr_thread_mutex.h 22 * @brief APR Thread Mutex Routines 23 */ 24 25 #include "apr.h" 26 #include "apr_errno.h" 27 28 #ifdef __cplusplus 29 extern "C" { 30 #endif /* __cplusplus */ 31 32 #if APR_HAS_THREADS || defined(DOXYGEN) 33 34 /** 35 * @defgroup apr_thread_mutex Thread Mutex Routines 36 * @ingroup APR 37 * @{ 38 */ 39 40 /** Opaque thread-local mutex structure */ 41 typedef struct apr_thread_mutex_t apr_thread_mutex_t; 42 43 #define APR_THREAD_MUTEX_DEFAULT 0x0 /**< platform-optimal lock behavior */ 44 #define APR_THREAD_MUTEX_NESTED 0x1 /**< enable nested (recursive) locks */ 45 #define APR_THREAD_MUTEX_UNNESTED 0x2 /**< disable nested locks */ 46 #define APR_THREAD_MUTEX_TIMED 0x4 /**< enable timed locks */ 47 48 /* Delayed the include to avoid a circular reference */ 49 #include "apr_pools.h" 50 #include "apr_time.h" 51 52 /** 53 * Create and initialize a mutex that can be used to synchronize threads. 54 * @param mutex the memory address where the newly created mutex will be 55 * stored. 56 * @param flags Or'ed value of: 57 * <PRE> 58 * APR_THREAD_MUTEX_DEFAULT platform-optimal lock behavior. 59 * APR_THREAD_MUTEX_NESTED enable nested (recursive) locks. 60 * APR_THREAD_MUTEX_UNNESTED disable nested locks (non-recursive). 61 * </PRE> 62 * @param pool the pool from which to allocate the mutex. 63 * @warning Be cautious in using APR_THREAD_MUTEX_DEFAULT. While this is the 64 * most optimal mutex based on a given platform's performance characteristics, 65 * it will behave as either a nested or an unnested lock. 66 */ 67 APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex, 68 unsigned int flags, 69 apr_pool_t *pool); 70 /** 71 * Acquire the lock for the given mutex. If the mutex is already locked, 72 * the current thread will be put to sleep until the lock becomes available. 73 * @param mutex the mutex on which to acquire the lock. 74 */ 75 APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex); 76 77 /** 78 * Attempt to acquire the lock for the given mutex. If the mutex has already 79 * been acquired, the call returns immediately with APR_EBUSY. Note: it 80 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 81 * if the return value was APR_EBUSY, for portability reasons. 82 * @param mutex the mutex on which to attempt the lock acquiring. 83 */ 84 APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex); 85 86 /** 87 * Attempt to acquire the lock for the given mutex until timeout expires. 88 * If the acquisition time outs, the call returns with APR_TIMEUP. 89 * @param mutex the mutex on which to attempt the lock acquiring. 90 * @param timeout the relative timeout (microseconds). 91 * @note A timeout negative or nul means immediate attempt, returning 92 * APR_TIMEUP without blocking if it the lock is already acquired. 93 */ 94 APR_DECLARE(apr_status_t) apr_thread_mutex_timedlock(apr_thread_mutex_t *mutex, 95 apr_interval_time_t timeout); 96 97 /** 98 * Release the lock for the given mutex. 99 * @param mutex the mutex from which to release the lock. 100 */ 101 APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex); 102 103 /** 104 * Destroy the mutex and free the memory associated with the lock. 105 * @param mutex the mutex to destroy. 106 */ 107 APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex); 108 109 /** 110 * Get the pool used by this thread_mutex. 111 * @return apr_pool_t the pool 112 */ 113 APR_POOL_DECLARE_ACCESSOR(thread_mutex); 114 115 #endif /* APR_HAS_THREADS */ 116 117 /** @} */ 118 119 #ifdef __cplusplus 120 } 121 #endif 122 123 #endif /* ! APR_THREAD_MUTEX_H */ 124