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                          __attribute__((nonnull(1)));
76
77/**
78 * Destroy an allocator
79 * @param allocator The allocator to be destroyed
80 * @remark Any memnodes not given back to the allocator prior to destroying
81 *         will _not_ be free()d.
82 */
83APR_DECLARE(void) apr_allocator_destroy(apr_allocator_t *allocator)
84                  __attribute__((nonnull(1)));
85
86/**
87 * Allocate a block of mem from the allocator
88 * @param allocator The allocator to allocate from
89 * @param size The size of the mem to allocate (excluding the
90 *        memnode structure)
91 */
92APR_DECLARE(apr_memnode_t *) apr_allocator_alloc(apr_allocator_t *allocator,
93                                                 apr_size_t size)
94                             __attribute__((nonnull(1)));
95
96/**
97 * Free a list of blocks of mem, giving them back to the allocator.
98 * The list is typically terminated by a memnode with its next field
99 * set to NULL.
100 * @param allocator The allocator to give the mem back to
101 * @param memnode The memory node to return
102 */
103APR_DECLARE(void) apr_allocator_free(apr_allocator_t *allocator,
104                                     apr_memnode_t *memnode)
105                  __attribute__((nonnull(1,2)));
106
107/**
108 * Get the true size that would be allocated for the given size (including
109 * the header and alignment).
110 * @param allocator The allocator from which to the memory would be allocated
111 * @param size The size to align
112 * @return The aligned size (or zero on apr_size_t overflow)
113 */
114APR_DECLARE(apr_size_t) apr_allocator_align(apr_allocator_t *allocator,
115                                            apr_size_t size);
116
117#include "apr_pools.h"
118
119/**
120 * Set the owner of the allocator
121 * @param allocator The allocator to set the owner for
122 * @param pool The pool that is to own the allocator
123 * @remark Typically pool is the highest level pool using the allocator
124 */
125/*
126 * XXX: see if we can come up with something a bit better.  Currently
127 * you can make a pool an owner, but if the pool doesn't use the allocator
128 * the allocator will never be destroyed.
129 */
130APR_DECLARE(void) apr_allocator_owner_set(apr_allocator_t *allocator,
131                                          apr_pool_t *pool)
132                  __attribute__((nonnull(1)));
133
134/**
135 * Get the current owner of the allocator
136 * @param allocator The allocator to get the owner from
137 */
138APR_DECLARE(apr_pool_t *) apr_allocator_owner_get(apr_allocator_t *allocator)
139                          __attribute__((nonnull(1)));
140
141/**
142 * Set the current threshold at which the allocator should start
143 * giving blocks back to the system.
144 * @param allocator The allocator to set the threshold on
145 * @param size The threshold.  0 == unlimited.
146 */
147APR_DECLARE(void) apr_allocator_max_free_set(apr_allocator_t *allocator,
148                                             apr_size_t size)
149                  __attribute__((nonnull(1)));
150
151#include "apr_thread_mutex.h"
152
153#if APR_HAS_THREADS
154/**
155 * Set a mutex for the allocator to use
156 * @param allocator The allocator to set the mutex for
157 * @param mutex The mutex
158 */
159APR_DECLARE(void) apr_allocator_mutex_set(apr_allocator_t *allocator,
160                                          apr_thread_mutex_t *mutex)
161                  __attribute__((nonnull(1)));
162
163/**
164 * Get the mutex currently set for the allocator
165 * @param allocator The allocator
166 */
167APR_DECLARE(apr_thread_mutex_t *) apr_allocator_mutex_get(
168                                          apr_allocator_t *allocator)
169                                  __attribute__((nonnull(1)));
170
171#endif /* APR_HAS_THREADS */
172
173/** @} */
174
175#ifdef __cplusplus
176}
177#endif
178
179#endif /* !APR_ALLOCATOR_H */
180