mem-pool.c

   1 /*
   2  * Memory Pool implementation logic.
   3  */
   4
   5 #include "cache.h"
   6 #include "mem-pool.h"
   7
   8 #define BLOCK_GROWTH_SIZE (1024 * 1024 - sizeof(struct mp_block))
   9
  10 /*
  11  * Allocate a new mp_block and insert it after the block specified in
  12  * `insert_after`. If `insert_after` is NULL, then insert block at the
  13  * head of the linked list.
  14  */
  15 static struct mp_block *mem_pool_alloc_block(struct mem_pool *pool,
  16                                              size_t block_alloc,
  17                                              struct mp_block *insert_after)
  18 {
  19         struct mp_block *p;
  20
  21         pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
  22         p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
  23
  24         p->next_free = (char *)p->space;
  25         p->end = p->next_free + block_alloc;
  26
  27         if (insert_after) {
  28                 p->next_block = insert_after->next_block;
  29                 insert_after->next_block = p;
  30         } else {
  31                 p->next_block = pool->mp_block;
  32                 pool->mp_block = p;
  33         }
  34
  35         return p;
  36 }
  37
  38 void mem_pool_init(struct mem_pool *pool, size_t initial_size)
  39 {
  40         memset(pool, 0, sizeof(*pool));
  41         pool->block_alloc = BLOCK_GROWTH_SIZE;
  42
  43         if (initial_size > 0)
  44                 mem_pool_alloc_block(pool, initial_size, NULL);
  45 }
  46
  47 void mem_pool_discard(struct mem_pool *pool, int invalidate_memory)
  48 {
  49         struct mp_block *block, *block_to_free;
  50
  51         block = pool->mp_block;
  52         while (block)
  53         {
  54                 block_to_free = block;
  55                 block = block->next_block;
  56
  57                 if (invalidate_memory)
  58                         memset(block_to_free->space, 0xDD, ((char *)block_to_free->end) - ((char *)block_to_free->space));
  59
  60                 free(block_to_free);
  61         }
  62
  63         pool->mp_block = NULL;
  64         pool->pool_alloc = 0;
  65 }
  66
  67 void *mem_pool_alloc(struct mem_pool *pool, size_t len)
  68 {
  69         struct mp_block *p = NULL;
  70         void *r;
  71
  72         /* round up to a 'uintmax_t' alignment */
  73         if (len & (sizeof(uintmax_t) - 1))
  74                 len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
  75
  76         if (pool->mp_block &&
  77             pool->mp_block->end - pool->mp_block->next_free >= len)
  78                 p = pool->mp_block;
  79
  80         if (!p) {
  81                 if (len >= (pool->block_alloc / 2))
  82                         return mem_pool_alloc_block(pool, len, pool->mp_block);
  83
  84                 p = mem_pool_alloc_block(pool, pool->block_alloc, NULL);
  85         }
  86
  87         r = p->next_free;
  88         p->next_free += len;
  89         return r;
  90 }
  91
  92 void *mem_pool_calloc(struct mem_pool *pool, size_t count, size_t size)
  93 {
  94         size_t len = st_mult(count, size);
  95         void *r = mem_pool_alloc(pool, len);
  96         memset(r, 0, len);
  97         return r;
  98 }
  99
 100 char *mem_pool_strdup(struct mem_pool *pool, const char *str)
 101 {
 102         size_t len = strlen(str) + 1;
 103         char *ret = mem_pool_alloc(pool, len);
 104
 105         return memcpy(ret, str, len);
 106 }
 107
 108 char *mem_pool_strndup(struct mem_pool *pool, const char *str, size_t len)
 109 {
 110         char *p = memchr(str, '\0', len);
 111         size_t actual_len = (p ? p - str : len);
 112         char *ret = mem_pool_alloc(pool, actual_len+1);
 113
 114         ret[actual_len] = '\0';
 115         return memcpy(ret, str, actual_len);
 116 }
 117
 118 int mem_pool_contains(struct mem_pool *pool, void *mem)
 119 {
 120         struct mp_block *p;
 121
 122         /* Check if memory is allocated in a block */
 123         for (p = pool->mp_block; p; p = p->next_block)
 124                 if ((mem >= ((void *)p->space)) &&
 125                     (mem < ((void *)p->end)))
 126                         return 1;
 127
 128         return 0;
 129 }
 130
 131 void mem_pool_combine(struct mem_pool *dst, struct mem_pool *src)
 132 {
 133         struct mp_block *p;
 134
 135         /* Append the blocks from src to dst */
 136         if (dst->mp_block && src->mp_block) {
 137                 /*
 138                  * src and dst have blocks, append
 139                  * blocks from src to dst.
 140                  */
 141                 p = dst->mp_block;
 142                 while (p->next_block)
 143                         p = p->next_block;
 144
 145                 p->next_block = src->mp_block;
 146         } else if (src->mp_block) {
 147                 /*
 148                  * src has blocks, dst is empty.
 149                  */
 150                 dst->mp_block = src->mp_block;
 151         } else {
 152                 /* src is empty, nothing to do. */
 153         }
 154
 155         dst->pool_alloc += src->pool_alloc;
 156         src->pool_alloc = 0;
 157         src->mp_block = NULL;
 158 }