src/basic/mempool.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010-2014 Lennart Poettering
   6   Copyright 2014 Michal Schmidt
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdint.h>
  23 #include <stdlib.h>
  24
  25 #include "macro.h"
  26 #include "mempool.h"
  27 #include "util.h"
  28
  29 struct pool {
  30         struct pool *next;
  31         unsigned n_tiles;
  32         unsigned n_used;
  33 };
  34
  35 void* mempool_alloc_tile(struct mempool *mp) {
  36         unsigned i;
  37
  38         /* When a tile is released we add it to the list and simply
  39          * place the next pointer at its offset 0. */
  40
  41         assert(mp->tile_size >= sizeof(void*));
  42         assert(mp->at_least > 0);
  43
  44         if (mp->freelist) {
  45                 void *r;
  46
  47                 r = mp->freelist;
  48                 mp->freelist = * (void**) mp->freelist;
  49                 return r;
  50         }
  51
  52         if (_unlikely_(!mp->first_pool) ||
  53             _unlikely_(mp->first_pool->n_used >= mp->first_pool->n_tiles)) {
  54                 unsigned n;
  55                 size_t size;
  56                 struct pool *p;
  57
  58                 n = mp->first_pool ? mp->first_pool->n_tiles : 0;
  59                 n = MAX(mp->at_least, n * 2);
  60                 size = PAGE_ALIGN(ALIGN(sizeof(struct pool)) + n*mp->tile_size);
  61                 n = (size - ALIGN(sizeof(struct pool))) / mp->tile_size;
  62
  63                 p = malloc(size);
  64                 if (!p)
  65                         return NULL;
  66
  67                 p->next = mp->first_pool;
  68                 p->n_tiles = n;
  69                 p->n_used = 0;
  70
  71                 mp->first_pool = p;
  72         }
  73
  74         i = mp->first_pool->n_used++;
  75
  76         return ((uint8_t*) mp->first_pool) + ALIGN(sizeof(struct pool)) + i*mp->tile_size;
  77 }
  78
  79 void* mempool_alloc0_tile(struct mempool *mp) {
  80         void *p;
  81
  82         p = mempool_alloc_tile(mp);
  83         if (p)
  84                 memzero(p, mp->tile_size);
  85         return p;
  86 }
  87
  88 void mempool_free_tile(struct mempool *mp, void *p) {
  89         * (void**) p = mp->freelist;
  90         mp->freelist = p;
  91 }
  92
  93 #ifdef VALGRIND
  94
  95 void mempool_drop(struct mempool *mp) {
  96         struct pool *p = mp->first_pool;
  97         while (p) {
  98                 struct pool *n;
  99                 n = p->next;
 100                 free(p);
 101                 p = n;
 102         }
 103 }
 104
 105 #endif