include/apr_reslist.h

   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_RESLIST_H
  18 #define APR_RESLIST_H
  19
  20 /**
  21  * @file apr_reslist.h
  22  * @brief APR-UTIL Resource List Routines
  23  */
  24
  25 #include "apr.h"
  26 #include "apu.h"
  27 #include "apr_pools.h"
  28 #include "apr_errno.h"
  29 #include "apr_time.h"
  30
  31 /**
  32  * @defgroup APR_Util_RL Resource List Routines
  33  * @ingroup APR_Util
  34  * @{
  35  */
  36
  37 #ifdef __cplusplus
  38 extern "C" {
  39 #endif /* __cplusplus */
  40
  41 /** Opaque resource list object */
  42 typedef struct apr_reslist_t apr_reslist_t;
  43
  44 /* Generic constructor called by resource list when it needs to create a
  45  * resource.
  46  * @param resource opaque resource
  47  * @param param flags
  48  * @param pool  Pool
  49  */
  50 typedef apr_status_t (*apr_reslist_constructor)(void **resource, void *params,
  51                                                 apr_pool_t *pool);
  52
  53 /* Generic destructor called by resource list when it needs to destroy a
  54  * resource.
  55  * @param resource opaque resource
  56  * @param param flags
  57  * @param pool  Pool
  58  */
  59 typedef apr_status_t (*apr_reslist_destructor)(void *resource, void *params,
  60                                                apr_pool_t *pool);
  61
  62 /* Cleanup order modes */
  63 #define APR_RESLIST_CLEANUP_DEFAULT  0       /**< default pool cleanup */
  64 #define APR_RESLIST_CLEANUP_FIRST    1       /**< use pool pre cleanup */
  65
  66 /**
  67  * Create a new resource list with the following parameters:
  68  * @param reslist An address where the pointer to the new resource
  69  *                list will be stored.
  70  * @param min Allowed minimum number of available resources. Zero
  71  *            creates new resources only when needed.
  72  * @param smax Resources will be destroyed to meet this maximum
  73  *             restriction as they expire.
  74  * @param hmax Absolute maximum limit on the number of total resources.
  75  * @param ttl If non-zero, sets the maximum amount of time a resource
  76  *               may be available while exceeding the soft limit.
  77  * @param con Constructor routine that is called to create a new resource.
  78  * @param de Destructor routine that is called to destroy an expired resource.
  79  * @param params Passed to constructor and deconstructor
  80  * @param pool The pool from which to create this resoure list. Also the
  81  *             same pool that is passed to the constructor and destructor
  82  *             routines.
  83  * @remark If APR has been compiled without thread support, hmax will be
  84  *         automatically set to 1 and values of min and smax will be forced to
  85  *         1 for any non-zero value.
  86  */
  87 APU_DECLARE(apr_status_t) apr_reslist_create(apr_reslist_t **reslist,
  88                                              int min, int smax, int hmax,
  89                                              apr_interval_time_t ttl,
  90                                              apr_reslist_constructor con,
  91                                              apr_reslist_destructor de,
  92                                              void *params,
  93                                              apr_pool_t *pool);
  94
  95 /**
  96  * Destroy the given resource list and all resources controlled by
  97  * this list.
  98  * FIXME: Should this block until all resources become available,
  99  *        or maybe just destroy all the free ones, or maybe destroy
 100  *        them even though they might be in use by something else?
 101  *        Currently it will abort if there are resources that haven't
 102  *        been released, so there is an assumption that all resources
 103  *        have been released to the list before calling this function.
 104  * @param reslist The reslist to destroy
 105  */
 106 APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist);
 107
 108 /**
 109  * Retrieve a resource from the list, creating a new one if necessary.
 110  * If we have met our maximum number of resources, we will block
 111  * until one becomes available.
 112  */
 113 APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
 114                                               void **resource);
 115
 116 /**
 117  * Return a resource back to the list of available resources.
 118  */
 119 APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist,
 120                                               void *resource);
 121
 122 /**
 123  * Set the timeout the acquire will wait for a free resource
 124  * when the maximum number of resources is exceeded.
 125  * @param reslist The resource list.
 126  * @param timeout Timeout to wait. The zero waits forewer.
 127  */
 128 APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist,
 129                                           apr_interval_time_t timeout);
 130
 131 /**
 132  * Return the number of outstanding resources.
 133  * @param reslist The resource list.
 134  */
 135 APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist);
 136
 137 /**
 138  * Invalidate a resource in the pool - e.g. a database connection
 139  * that returns a "lost connection" error and can't be restored.
 140  * Use this instead of apr_reslist_release if the resource is bad.
 141  */
 142 APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist,
 143                                                  void *resource);
 144
 145 /**
 146  * Perform routine maintenance on the resource list. This call
 147  * may instantiate new resources or expire old resources.
 148  * @param reslist The resource list.
 149  */
 150 APU_DECLARE(apr_status_t) apr_reslist_maintain(apr_reslist_t *reslist);
 151
 152 /**
 153  * Set reslist cleanup order.
 154  * @param reslist The resource list.
 155  * @param mode Cleanup order mode
 156  * <PRE>
 157  *           APR_RESLIST_CLEANUP_DEFAULT  default pool cleanup order
 158  *           APR_RESLIST_CLEANUP_FIRST    use pool pre cleanup
 159  * </PRE>
 160  * @remark If APR_RESLIST_CLEANUP_FIRST is used the destructors will
 161  * be called before child pools of the pool used to create the reslist
 162  * are destroyed. This allows to explicitly destroy the child pools
 163  * inside reslist destructors.
 164  */
 165 APU_DECLARE(void) apr_reslist_cleanup_order_set(apr_reslist_t *reslist,
 166                                                 apr_uint32_t mode);
 167
 168 #ifdef __cplusplus
 169 }
 170 #endif
 171
 172 /** @} */
 173
 174 #endif  /* ! APR_RESLIST_H */