Apache Portable Runtime
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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_RESLIST_H 00018 #define APR_RESLIST_H 00019 00020 /** 00021 * @file apr_reslist.h 00022 * @brief APR-UTIL Resource List Routines 00023 */ 00024 00025 #include "apr.h" 00026 #include "apu.h" 00027 #include "apr_pools.h" 00028 #include "apr_errno.h" 00029 #include "apr_time.h" 00030 00031 #if APR_HAS_THREADS 00032 00033 /** 00034 * @defgroup APR_Util_RL Resource List Routines 00035 * @ingroup APR_Util 00036 * @{ 00037 * @warning 00038 * <strong><em>Resource list data types and routines are only available when 00039 * threads are enabled (i.e. APR_HAS_THREADS is not zero).</em></strong> 00040 */ 00041 00042 #ifdef __cplusplus 00043 extern "C" { 00044 #endif /* __cplusplus */ 00045 00046 /** Opaque resource list object */ 00047 typedef struct apr_reslist_t apr_reslist_t; 00048 00049 /* Generic constructor called by resource list when it needs to create a 00050 * resource. 00051 * @param resource opaque resource 00052 * @param param flags 00053 * @param pool Pool 00054 */ 00055 typedef apr_status_t (*apr_reslist_constructor)(void **resource, void *params, 00056 apr_pool_t *pool); 00057 00058 /* Generic destructor called by resource list when it needs to destroy a 00059 * resource. 00060 * @param resource opaque resource 00061 * @param param flags 00062 * @param pool Pool 00063 */ 00064 typedef apr_status_t (*apr_reslist_destructor)(void *resource, void *params, 00065 apr_pool_t *pool); 00066 00067 /** 00068 * Create a new resource list with the following parameters: 00069 * @param reslist An address where the pointer to the new resource 00070 * list will be stored. 00071 * @param min Allowed minimum number of available resources. Zero 00072 * creates new resources only when needed. 00073 * @param smax Resources will be destroyed during reslist maintenance to 00074 * meet this maximum restriction as they expire (reach their ttl). 00075 * @param hmax Absolute maximum limit on the number of total resources. 00076 * @param ttl If non-zero, sets the maximum amount of time in microseconds an 00077 * unused resource is valid. Any resource which has exceeded this 00078 * time will be destroyed, either when encountered by 00079 * apr_reslist_acquire() or during reslist maintenance. 00080 * @param con Constructor routine that is called to create a new resource. 00081 * @param de Destructor routine that is called to destroy an expired resource. 00082 * @param params Passed to constructor and deconstructor 00083 * @param pool The pool from which to create this resource list. Also the 00084 * same pool that is passed to the constructor and destructor 00085 * routines. 00086 * @warning If you're creating a sub-pool of the pool passed into this 00087 * function in your constructor, you will need to follow some rules 00088 * when it comes to destruction of that sub-pool, as calling 00089 * apr_pool_destroy() outright on it in your destructor may create 00090 * double free situations. That is because by the time destructor is 00091 * called, the sub-pool may have already been destroyed. This also 00092 * means that in the destructor, memory from the sub-pool should be 00093 * treated as invalid. For examples of how to do this correctly, see 00094 * mod_dbd of Apache 2.2 and memcache support in APR Util 1.3. 00095 */ 00096 APU_DECLARE(apr_status_t) apr_reslist_create(apr_reslist_t **reslist, 00097 int min, int smax, int hmax, 00098 apr_interval_time_t ttl, 00099 apr_reslist_constructor con, 00100 apr_reslist_destructor de, 00101 void *params, 00102 apr_pool_t *pool); 00103 00104 /** 00105 * Destroy the given resource list and all resources controlled by 00106 * this list. 00107 * FIXME: Should this block until all resources become available, 00108 * or maybe just destroy all the free ones, or maybe destroy 00109 * them even though they might be in use by something else? 00110 * Currently it will abort if there are resources that haven't 00111 * been released, so there is an assumption that all resources 00112 * have been released to the list before calling this function. 00113 * @param reslist The reslist to destroy 00114 */ 00115 APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist); 00116 00117 /** 00118 * Retrieve a resource from the list, creating a new one if necessary. 00119 * If we have met our maximum number of resources, we will block 00120 * until one becomes available. 00121 */ 00122 APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist, 00123 void **resource); 00124 00125 /** 00126 * Return a resource back to the list of available resources. 00127 */ 00128 APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist, 00129 void *resource); 00130 00131 /** 00132 * Set the timeout the acquire will wait for a free resource 00133 * when the maximum number of resources is exceeded. 00134 * @param reslist The resource list. 00135 * @param timeout Timeout to wait. The zero waits forever. 00136 */ 00137 APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist, 00138 apr_interval_time_t timeout); 00139 00140 /** 00141 * Return the number of outstanding resources. 00142 * @param reslist The resource list. 00143 */ 00144 APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist); 00145 00146 /** 00147 * Invalidate a resource in the pool - e.g. a database connection 00148 * that returns a "lost connection" error and can't be restored. 00149 * Use this instead of apr_reslist_release if the resource is bad. 00150 */ 00151 APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist, 00152 void *resource); 00153 00154 00155 #ifdef __cplusplus 00156 } 00157 #endif 00158 00159 /** @} */ 00160 00161 #endif /* APR_HAS_THREADS */ 00162 00163 #endif /* ! APR_RESLIST_H */