xref: /PHP-5.6/ext/mysqlnd/mysqlnd_block_alloc.c (revision 49493a2d)
1 /*
2   +----------------------------------------------------------------------+
3   | PHP Version 5                                                        |
4   +----------------------------------------------------------------------+
5   | Copyright (c) 2006-2016 The PHP Group                                |
6   +----------------------------------------------------------------------+
7   | This source file is subject to version 3.01 of the PHP license,      |
8   | that is bundled with this package in the file LICENSE, and is        |
9   | available through the world-wide-web at the following url:           |
10   | http://www.php.net/license/3_01.txt                                  |
11   | If you did not receive a copy of the PHP license and are unable to   |
12   | obtain it through the world-wide-web, please send a note to          |
13   | license@php.net so we can mail you a copy immediately.               |
14   +----------------------------------------------------------------------+
15   | Authors: Georg Richter <georg@mysql.com>                             |
16   |          Andrey Hristov <andrey@mysql.com>                           |
17   |          Ulf Wendel <uwendel@mysql.com>                              |
18   +----------------------------------------------------------------------+
19 */
20 
21 /* $Id$ */
22 
23 #include "php.h"
24 #include "mysqlnd.h"
25 #include "mysqlnd_block_alloc.h"
26 #include "mysqlnd_debug.h"
27 #include "mysqlnd_priv.h"
28 
29 
30 /* {{{ mysqlnd_mempool_free_chunk */
31 static void
mysqlnd_mempool_free_chunk(MYSQLND_MEMORY_POOL_CHUNK * chunk TSRMLS_DC)32 mysqlnd_mempool_free_chunk(MYSQLND_MEMORY_POOL_CHUNK * chunk TSRMLS_DC)
33 {
34 	MYSQLND_MEMORY_POOL * pool = chunk->pool;
35 	DBG_ENTER("mysqlnd_mempool_free_chunk");
36 	if (chunk->from_pool) {
37 		/* Try to back-off and guess if this is the last block allocated */
38 		if (chunk->ptr == (pool->arena + (pool->arena_size - pool->free_size - chunk->size))) {
39 			/*
40 				This was the last allocation. Lucky us, we can free
41 				a bit of memory from the pool. Next time we will return from the same ptr.
42 			*/
43 			pool->free_size += chunk->size;
44 		}
45 		pool->refcount--;
46 	} else {
47 		mnd_free(chunk->ptr);
48 	}
49 	mnd_free(chunk);
50 	DBG_VOID_RETURN;
51 }
52 /* }}} */
53 
54 
55 /* {{{ mysqlnd_mempool_resize_chunk */
56 static enum_func_status
mysqlnd_mempool_resize_chunk(MYSQLND_MEMORY_POOL_CHUNK * chunk,unsigned int size TSRMLS_DC)57 mysqlnd_mempool_resize_chunk(MYSQLND_MEMORY_POOL_CHUNK * chunk, unsigned int size TSRMLS_DC)
58 {
59 	DBG_ENTER("mysqlnd_mempool_resize_chunk");
60 	if (chunk->from_pool) {
61 		MYSQLND_MEMORY_POOL * pool = chunk->pool;
62 		/* Try to back-off and guess if this is the last block allocated */
63 		if (chunk->ptr == (pool->arena + (pool->arena_size - pool->free_size - chunk->size))) {
64 			/*
65 				This was the last allocation. Lucky us, we can free
66 				a bit of memory from the pool. Next time we will return from the same ptr.
67 			*/
68 			if ((chunk->size + pool->free_size) < size) {
69 				zend_uchar *new_ptr;
70 				new_ptr = mnd_malloc(size);
71 				if (!new_ptr) {
72 					DBG_RETURN(FAIL);
73 				}
74 				memcpy(new_ptr, chunk->ptr, chunk->size);
75 				chunk->ptr = new_ptr;
76 				pool->free_size += chunk->size;
77 				chunk->size = size;
78 				chunk->pool = NULL; /* now we have no pool memory */
79 				pool->refcount--;
80 			} else {
81 				/* If the chunk is > than asked size then free_memory increases, otherwise decreases*/
82 				pool->free_size += (chunk->size - size);
83 			}
84 		} else {
85 			/* Not last chunk, if the user asks for less, give it to him */
86 			if (chunk->size >= size) {
87 				; /* nop */
88 			} else {
89 				zend_uchar *new_ptr;
90 				new_ptr = mnd_malloc(size);
91 				if (!new_ptr) {
92 					DBG_RETURN(FAIL);
93 				}
94 				memcpy(new_ptr, chunk->ptr, chunk->size);
95 				chunk->ptr = new_ptr;
96 				chunk->size = size;
97 				chunk->pool = NULL; /* now we have non-pool memory */
98 				pool->refcount--;
99 			}
100 		}
101 	} else {
102 		zend_uchar *new_ptr = mnd_realloc(chunk->ptr, size);
103 		if (!new_ptr) {
104 			DBG_RETURN(FAIL);
105 		}
106 		chunk->ptr = new_ptr;
107 	}
108 	DBG_RETURN(PASS);
109 }
110 /* }}} */
111 
112 
113 /* {{{ mysqlnd_mempool_get_chunk */
114 static
mysqlnd_mempool_get_chunk(MYSQLND_MEMORY_POOL * pool,unsigned int size TSRMLS_DC)115 MYSQLND_MEMORY_POOL_CHUNK * mysqlnd_mempool_get_chunk(MYSQLND_MEMORY_POOL * pool, unsigned int size TSRMLS_DC)
116 {
117 	MYSQLND_MEMORY_POOL_CHUNK *chunk = NULL;
118 	DBG_ENTER("mysqlnd_mempool_get_chunk");
119 
120 	chunk = mnd_malloc(sizeof(MYSQLND_MEMORY_POOL_CHUNK));
121 	if (chunk) {
122 		chunk->free_chunk = mysqlnd_mempool_free_chunk;
123 		chunk->resize_chunk = mysqlnd_mempool_resize_chunk;
124 		chunk->size = size;
125 		/*
126 		  Should not go over MYSQLND_MAX_PACKET_SIZE, since we
127 		  expect non-arena memory in mysqlnd_wireprotocol.c . We
128 		  realloc the non-arena memory.
129 		*/
130 		chunk->pool = pool;
131 		if (size > pool->free_size) {
132 			chunk->from_pool = FALSE;
133 			chunk->ptr = mnd_malloc(size);
134 			if (!chunk->ptr) {
135 				chunk->free_chunk(chunk TSRMLS_CC);
136 				chunk = NULL;
137 			}
138 		} else {
139 			chunk->from_pool = TRUE;
140 			++pool->refcount;
141 			chunk->ptr = pool->arena + (pool->arena_size - pool->free_size);
142 			/* Last step, update free_size */
143 			pool->free_size -= size;
144 		}
145 	}
146 	DBG_RETURN(chunk);
147 }
148 /* }}} */
149 
150 
151 /* {{{ mysqlnd_mempool_create */
152 PHPAPI MYSQLND_MEMORY_POOL *
mysqlnd_mempool_create(size_t arena_size TSRMLS_DC)153 mysqlnd_mempool_create(size_t arena_size TSRMLS_DC)
154 {
155 	/* We calloc, because we free(). We don't mnd_calloc()  for a reason. */
156 	MYSQLND_MEMORY_POOL * ret = mnd_calloc(1, sizeof(MYSQLND_MEMORY_POOL));
157 	DBG_ENTER("mysqlnd_mempool_create");
158 	if (ret) {
159 		ret->get_chunk = mysqlnd_mempool_get_chunk;
160 		ret->free_size = ret->arena_size = arena_size ? arena_size : 0;
161 		ret->refcount = 0;
162 		/* OOM ? */
163 		ret->arena = mnd_malloc(ret->arena_size);
164 		if (!ret->arena) {
165 			mysqlnd_mempool_destroy(ret TSRMLS_CC);
166 			ret = NULL;
167 		}
168 	}
169 	DBG_RETURN(ret);
170 }
171 /* }}} */
172 
173 
174 /* {{{ mysqlnd_mempool_destroy */
175 PHPAPI void
mysqlnd_mempool_destroy(MYSQLND_MEMORY_POOL * pool TSRMLS_DC)176 mysqlnd_mempool_destroy(MYSQLND_MEMORY_POOL * pool TSRMLS_DC)
177 {
178 	DBG_ENTER("mysqlnd_mempool_destroy");
179 	/* mnd_free will reference LOCK_access and might crash, depending on the caller...*/
180 	mnd_free(pool->arena);
181 	mnd_free(pool);
182 	DBG_VOID_RETURN;
183 }
184 /* }}} */
185 
186 
187 /*
188  * Local variables:
189  * tab-width: 4
190  * c-basic-offset: 4
191  * End:
192  * vim600: noet sw=4 ts=4 fdm=marker
193  * vim<600: noet sw=4 ts=4
194  */
195