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
38extern "C" {
39#endif /* __cplusplus */
40
41/** Opaque resource list object */
42typedef 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 params flags
48 * @param pool  Pool
49 */
50typedef 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 params flags
57 * @param pool  Pool
58 */
59typedef 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 during reslist maintenance to
73 *             meet this maximum restriction as they expire (reach their ttl).
74 * @param hmax Absolute maximum limit on the number of total resources.
75 * @param ttl If non-zero, sets the maximum amount of time in microseconds an
76 *            unused resource is valid.  Any resource which has exceeded this
77 *            time will be destroyed, either when encountered by
78 *            apr_reslist_acquire() or during reslist maintenance.
79 * @param con Constructor routine that is called to create a new resource.
80 * @param de Destructor routine that is called to destroy an expired resource.
81 * @param params Passed to constructor and deconstructor
82 * @param pool The pool from which to create this resource list. Also the
83 *             same pool that is passed to the constructor and destructor
84 *             routines.
85 * @remark If APR has been compiled without thread support, hmax will be
86 *         automatically set to 1 and values of min and smax will be forced to
87 *         1 for any non-zero value.
88 */
89APU_DECLARE(apr_status_t) apr_reslist_create(apr_reslist_t **reslist,
90                                             int min, int smax, int hmax,
91                                             apr_interval_time_t ttl,
92                                             apr_reslist_constructor con,
93                                             apr_reslist_destructor de,
94                                             void *params,
95                                             apr_pool_t *pool);
96
97/**
98 * Destroy the given resource list and all resources controlled by
99 * this list.
100 * FIXME: Should this block until all resources become available,
101 *        or maybe just destroy all the free ones, or maybe destroy
102 *        them even though they might be in use by something else?
103 *        Currently it will abort if there are resources that haven't
104 *        been released, so there is an assumption that all resources
105 *        have been released to the list before calling this function.
106 * @param reslist The reslist to destroy
107 */
108APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist);
109
110/**
111 * Retrieve a resource from the list, creating a new one if necessary.
112 * If we have met our maximum number of resources, we will block
113 * until one becomes available.
114 * @param reslist The resource list.
115 * @param resource An address where the pointer to the resource
116 *                will be stored.
117 */
118APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
119                                              void **resource);
120
121/**
122 * Return a resource back to the list of available resources.
123 * @param reslist The resource list.
124 * @param resource The resource to return to the list.
125 */
126APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist,
127                                              void *resource);
128
129/**
130 * Set the timeout the acquire will wait for a free resource
131 * when the maximum number of resources is exceeded.
132 * @param reslist The resource list.
133 * @param timeout Timeout to wait. The zero waits forever.
134 */
135APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist,
136                                          apr_interval_time_t timeout);
137
138/**
139 * Return the number of outstanding resources.
140 * @param reslist The resource list.
141 */
142APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist);
143
144/**
145 * Invalidate a resource in the pool - e.g. a database connection
146 * that returns a "lost connection" error and can't be restored.
147 * Use this instead of apr_reslist_release if the resource is bad.
148 * @param reslist The resource list.
149 * @param resource The resource to invalidate.
150 */
151APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist,
152                                                 void *resource);
153
154/**
155 * Perform routine maintenance on the resource list. This call
156 * may instantiate new resources or expire old resources.
157 * @param reslist The resource list.
158 */
159APU_DECLARE(apr_status_t) apr_reslist_maintain(apr_reslist_t *reslist);
160
161/**
162 * Set reslist cleanup order.
163 * @param reslist The resource list.
164 * @param mode Cleanup order mode
165 * <PRE>
166 *           APR_RESLIST_CLEANUP_DEFAULT  default pool cleanup order
167 *           APR_RESLIST_CLEANUP_FIRST    use pool pre cleanup
168 * </PRE>
169 * @remark If APR_RESLIST_CLEANUP_FIRST is used the destructors will
170 * be called before child pools of the pool used to create the reslist
171 * are destroyed. This allows to explicitly destroy the child pools
172 * inside reslist destructors.
173 */
174APU_DECLARE(void) apr_reslist_cleanup_order_set(apr_reslist_t *reslist,
175                                                apr_uint32_t mode);
176
177#ifdef __cplusplus
178}
179#endif
180
181/** @} */
182
183#endif  /* ! APR_RESLIST_H */
184