apr_allocator.h revision 251886 
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_ALLOCATOR_H
18#define APR_ALLOCATOR_H
19
20/**
21 * @file apr_allocator.h
22 * @brief APR Internal Memory Allocation
23 */
24
25#include "apr.h"
26#include "apr_errno.h"
27#define APR_WANT_MEMFUNC /**< For no good reason? */
28#include "apr_want.h"
29
30#ifdef __cplusplus
31extern "C" {
32#endif
33
34/**
35 * @defgroup apr_allocator Internal Memory Allocation
36 * @ingroup APR
37 * @{
38 */
39
40/** the allocator structure */
41typedef struct apr_allocator_t apr_allocator_t;
42/** the structure which holds information about the allocation */
43typedef struct apr_memnode_t apr_memnode_t;
44
45/** basic memory node structure
46 * @note The next, ref and first_avail fields are available for use by the
47 *       caller of apr_allocator_alloc(), the remaining fields are read-only.
48 *       The next field has to be used with caution and sensibly set when the
49 *       memnode is passed back to apr_allocator_free().  See apr_allocator_free()
50 *       for details.
51 *       The ref and first_avail fields will be properly restored by
52 *       apr_allocator_free().
53 */
54struct apr_memnode_t {
55    apr_memnode_t *next;            /**< next memnode */
56    apr_memnode_t **ref;            /**< reference to self */
57    apr_uint32_t   index;           /**< size */
58    apr_uint32_t   free_index;      /**< how much free */
59    char          *first_avail;     /**< pointer to first free memory */
60    char          *endp;            /**< pointer to end of free memory */
61};
62
63/** The base size of a memory node - aligned.  */
64#define APR_MEMNODE_T_SIZE APR_ALIGN_DEFAULT(sizeof(apr_memnode_t))
65
66/** Symbolic constants */
67#define APR_ALLOCATOR_MAX_FREE_UNLIMITED 0
68
69/**
70 * Create a new allocator
71 * @param allocator The allocator we have just created.
72 *
73 */
74APR_DECLARE(apr_status_t) apr_allocator_create(apr_allocator_t **allocator);
75
76/**
77 * Destroy an allocator
78 * @param allocator The allocator to be destroyed
79 * @remark Any memnodes not given back to the allocator prior to destroying
80 *         will _not_ be free()d.
81 */
82APR_DECLARE(void) apr_allocator_destroy(apr_allocator_t *allocator);
83
84/**
85 * Allocate a block of mem from the allocator
86 * @param allocator The allocator to allocate from
87 * @param size The size of the mem to allocate (excluding the
88 *        memnode structure)
89 */
90APR_DECLARE(apr_memnode_t *) apr_allocator_alloc(apr_allocator_t *allocator,
91                                                 apr_size_t size);
92
93/**
94 * Free a list of blocks of mem, giving them back to the allocator.
95 * The list is typically terminated by a memnode with its next field
96 * set to NULL.
97 * @param allocator The allocator to give the mem back to
98 * @param memnode The memory node to return
99 */
100APR_DECLARE(void) apr_allocator_free(apr_allocator_t *allocator,
101                                     apr_memnode_t *memnode);
102
103#include "apr_pools.h"
104
105/**
106 * Set the owner of the allocator
107 * @param allocator The allocator to set the owner for
108 * @param pool The pool that is to own the allocator
109 * @remark Typically pool is the highest level pool using the allocator
110 */
111/*
112 * XXX: see if we can come up with something a bit better.  Currently
113 * you can make a pool an owner, but if the pool doesn't use the allocator
114 * the allocator will never be destroyed.
115 */
116APR_DECLARE(void) apr_allocator_owner_set(apr_allocator_t *allocator,
117                                          apr_pool_t *pool);
118
119/**
120 * Get the current owner of the allocator
121 * @param allocator The allocator to get the owner from
122 */
123APR_DECLARE(apr_pool_t *) apr_allocator_owner_get(apr_allocator_t *allocator);
124
125/**
126 * Set the current threshold at which the allocator should start
127 * giving blocks back to the system.
128 * @param allocator The allocator the set the threshold on
129 * @param size The threshold.  0 == unlimited.
130 */
131APR_DECLARE(void) apr_allocator_max_free_set(apr_allocator_t *allocator,
132                                             apr_size_t size);
133
134#include "apr_thread_mutex.h"
135
136#if APR_HAS_THREADS
137/**
138 * Set a mutex for the allocator to use
139 * @param allocator The allocator to set the mutex for
140 * @param mutex The mutex
141 */
142APR_DECLARE(void) apr_allocator_mutex_set(apr_allocator_t *allocator,
143                                          apr_thread_mutex_t *mutex);
144
145/**
146 * Get the mutex currently set for the allocator
147 * @param allocator The allocator
148 */
149APR_DECLARE(apr_thread_mutex_t *) apr_allocator_mutex_get(
150                                      apr_allocator_t *allocator);
151
152#endif /* APR_HAS_THREADS */
153
154/** @} */
155
156#ifdef __cplusplus
157}
158#endif
159
160#endif /* !APR_ALLOCATOR_H */
161