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apr_allocator.h
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2  * contributor license agreements. See the NOTICE file distributed with
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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
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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,
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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
31 extern "C" {
32 #endif
33 
34 /**
35  * @defgroup apr_allocator Internal Memory Allocation
36  * @ingroup APR
37  * @{
38  */
39 
40 /** the allocator structure */
42 /** the structure which holds information about the allocation */
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  */
54 struct 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  */
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  */
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  */
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  */
104  apr_memnode_t *memnode)
105  __attribute__((nonnull(1,2)));
106 
107 #include "apr_pools.h"
108 
109 /**
110  * Set the owner of the allocator
111  * @param allocator The allocator to set the owner for
112  * @param pool The pool that is to own the allocator
113  * @remark Typically pool is the highest level pool using the allocator
114  */
115 /*
116  * XXX: see if we can come up with something a bit better. Currently
117  * you can make a pool an owner, but if the pool doesn't use the allocator
118  * the allocator will never be destroyed.
119  */
121  apr_pool_t *pool)
122  __attribute__((nonnull(1)));
123 
124 /**
125  * Get the current owner of the allocator
126  * @param allocator The allocator to get the owner from
127  */
129  __attribute__((nonnull(1)));
130 
131 /**
132  * Set the current threshold at which the allocator should start
133  * giving blocks back to the system.
134  * @param allocator The allocator to set the threshold on
135  * @param size The threshold. 0 == unlimited.
136  */
138  apr_size_t size)
139  __attribute__((nonnull(1)));
140 
141 #include "apr_thread_mutex.h"
142 
143 #if APR_HAS_THREADS
144 /**
145  * Set a mutex for the allocator to use
146  * @param allocator The allocator to set the mutex for
147  * @param mutex The mutex
148  */
150  apr_thread_mutex_t *mutex)
151  __attribute__((nonnull(1)));
152 
153 /**
154  * Get the mutex currently set for the allocator
155  * @param allocator The allocator
156  */
158  apr_allocator_t *allocator)
159  __attribute__((nonnull(1)));
160 
161 #endif /* APR_HAS_THREADS */
162 
163 /** @} */
164 
165 #ifdef __cplusplus
166 }
167 #endif
168 
169 #endif /* !APR_ALLOCATOR_H */