src/util/slab.h

   1 /*
   2  * Copyright 2010 Marek Olšák <maraeo@gmail.com>
   3  * Copyright 2016 Advanced Micro Devices, Inc.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * on the rights to use, copy, modify, merge, publish, distribute, sub
   9  * license, and/or sell copies of the Software, and to permit persons to whom
  10  * the Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  20  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  21  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  22  * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  23
  24 /**
  25  * Slab allocator for equally sized memory allocations.
  26  * The thread-safe path ("*_mt" functions) is usually slower than malloc/free.
  27  * The single-threaded path ("*_st" functions) is faster than malloc/free.
  28  */
  29
  30 #ifndef SLAB_H
  31 #define SLAB_H
  32
  33 #include "c11/threads.h"
  34
  35 /* The page is an array of allocations in one block. */
  36 struct slab_page_header {
  37    /* The header (linked-list pointers). */
  38    struct slab_page_header *prev, *next;
  39
  40    /* Memory after the last member is dedicated to the page itself.
  41     * The allocated size is always larger than this structure.
  42     */
  43 };
  44
  45 struct slab_mempool {
  46    mtx_t mutex;
  47    unsigned element_size;
  48    unsigned num_elements;
  49    struct slab_element_header *first_free;
  50    struct slab_page_header list;
  51 };
  52
  53 void slab_create(struct slab_mempool *pool,
  54                  unsigned item_size,
  55                  unsigned num_items);
  56 void slab_destroy(struct slab_mempool *pool);
  57 void *slab_alloc_st(struct slab_mempool *pool);
  58 void slab_free_st(struct slab_mempool *pool, void *ptr);
  59 void *slab_alloc_mt(struct slab_mempool *pool);
  60 void slab_free_mt(struct slab_mempool *pool, void *ptr);
  61
  62 #endif