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 /**
  63  * Create a new resource list with the following parameters:
  64  * @param reslist An address where the pointer to the new resource
  65  *                list will be stored.
  66  * @param min Allowed minimum number of available resources. Zero
  67  *            creates new resources only when needed.
  68  * @param smax Resources will be destroyed to meet this maximum
  69  *             restriction as they expire.
  70  * @param hmax Absolute maximum limit on the number of total resources.
  71  * @param ttl If non-zero, sets the maximum amount of time a resource
  72  *               may be available while exceeding the soft limit.
  73  * @param con Constructor routine that is called to create a new resource.
  74  * @param de Destructor routine that is called to destroy an expired resource.
  75  * @param params Passed to constructor and deconstructor
  76  * @param pool The pool from which to create this resoure list. Also the
  77  *             same pool that is passed to the constructor and destructor
  78  *             routines.
  79  * @remark If APR has been compiled without thread support, hmax will be
  80  *         automatically set to 1 and values of min and smax will be forced to
  81  *         1 for any non-zero value.
  82  */
  83 APU_DECLARE(apr_status_t) apr_reslist_create(apr_reslist_t **reslist,
  84                                              int min, int smax, int hmax,
  85                                              apr_interval_time_t ttl,
  86                                              apr_reslist_constructor con,
  87                                              apr_reslist_destructor de,
  88                                              void *params,
  89                                              apr_pool_t *pool);
  90
  91 /**
  92  * Destroy the given resource list and all resources controlled by
  93  * this list.
  94  * FIXME: Should this block until all resources become available,
  95  *        or maybe just destroy all the free ones, or maybe destroy
  96  *        them even though they might be in use by something else?
  97  *        Currently it will abort if there are resources that haven't
  98  *        been released, so there is an assumption that all resources
  99  *        have been released to the list before calling this function.
 100  * @param reslist The reslist to destroy
 101  */
 102 APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist);
 103
 104 /**
 105  * Retrieve a resource from the list, creating a new one if necessary.
 106  * If we have met our maximum number of resources, we will block
 107  * until one becomes available.
 108  */
 109 APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
 110                                               void **resource);
 111
 112 /**
 113  * Return a resource back to the list of available resources.
 114  */
 115 APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist,
 116                                               void *resource);
 117
 118 /**
 119  * Set the timeout the acquire will wait for a free resource
 120  * when the maximum number of resources is exceeded.
 121  * @param reslist The resource list.
 122  * @param timeout Timeout to wait. The zero waits forewer.
 123  */
 124 APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist,
 125                                           apr_interval_time_t timeout);
 126
 127 /**
 128  * Return the number of outstanding resources.
 129  * @param reslist The resource list.
 130  */
 131 APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist);
 132
 133 /**
 134  * Invalidate a resource in the pool - e.g. a database connection
 135  * that returns a "lost connection" error and can't be restored.
 136  * Use this instead of apr_reslist_release if the resource is bad.
 137  */
 138 APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist,
 139                                                  void *resource);
 140
 141
 142 #ifdef __cplusplus
 143 }
 144 #endif
 145
 146 /** @} */
 147
 148 #endif  /* ! APR_RESLIST_H */