src/basic/mempool.c

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