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  1. /*
  2.  * Copyright 2010 Marek Olšák <maraeo@gmail.com>
  3.  *
  4.  * Permission is hereby granted, free of charge, to any person obtaining a
  5.  * copy of this software and associated documentation files (the "Software"),
  6.  * to deal in the Software without restriction, including without limitation
  7.  * on the rights to use, copy, modify, merge, publish, distribute, sub
  8.  * license, and/or sell copies of the Software, and to permit persons to whom
  9.  * the Software is furnished to do so, subject to the following conditions:
  10.  *
  11.  * The above copyright notice and this permission notice (including the next
  12.  * paragraph) shall be included in all copies or substantial portions of the
  13.  * Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  18.  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  19.  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  20.  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  21.  * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  22.  
  23. /**
  24.  * @file
  25.  * Simple slab allocator for equally sized memory allocations.
  26.  * util_slab_alloc and util_slab_free have time complexity in O(1).
  27.  *
  28.  * Good for allocations which have very low lifetime and are allocated
  29.  * and freed very often. Use a profiler first to know if it's worth using it!
  30.  *
  31.  * Candidates: transfer_map
  32.  *
  33.  * @author Marek Olšák
  34.  */
  35.  
  36. #ifndef U_SLAB_H
  37. #define U_SLAB_H
  38.  
  39. #include "os/os_thread.h"
  40.  
  41. enum util_slab_threading {
  42.    UTIL_SLAB_SINGLETHREADED = FALSE,
  43.    UTIL_SLAB_MULTITHREADED = TRUE
  44. };
  45.  
  46. /* The page is an array of blocks (allocations). */
  47. struct util_slab_page {
  48.    /* The header (linked-list pointers). */
  49.    struct util_slab_page *prev, *next;
  50.  
  51.    /* Memory after the last member is dedicated to the page itself.
  52.     * The allocated size is always larger than this structure. */
  53. };
  54.  
  55. struct util_slab_mempool {
  56.    /* Public members. */
  57.    void *(*alloc)(struct util_slab_mempool *pool);
  58.    void (*free)(struct util_slab_mempool *pool, void *ptr);
  59.  
  60.    /* Private members. */
  61.    struct util_slab_block *first_free;
  62.  
  63.    struct util_slab_page list;
  64.  
  65.    unsigned block_size;
  66.    unsigned page_size;
  67.    unsigned num_blocks;
  68.    unsigned num_pages;
  69.    enum util_slab_threading threading;
  70.  
  71.    pipe_mutex mutex;
  72. };
  73.  
  74. void util_slab_create(struct util_slab_mempool *pool,
  75.                       unsigned item_size,
  76.                       unsigned num_blocks,
  77.                       enum util_slab_threading threading);
  78.  
  79. void util_slab_destroy(struct util_slab_mempool *pool);
  80.  
  81. void util_slab_set_thread_safety(struct util_slab_mempool *pool,
  82.                                  enum util_slab_threading threading);
  83.  
  84. #define util_slab_alloc(pool)     (pool)->alloc(pool)
  85. #define util_slab_free(pool, ptr) (pool)->free(pool, ptr)
  86.  
  87. #endif
  88.