u_slab.h revision 80f24c1575688e9cd4a5a811137f43b7e0a661bb 
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: get_transfer, user_buffer_create
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
41enum util_slab_threading {
42   UTIL_SLAB_SINGLETHREADED = FALSE,
43   UTIL_SLAB_MULTITHREADED = TRUE
44};
45
46/* The page is an array of blocks (allocations). */
47struct 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
55struct 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
74void util_slab_create(struct util_slab_mempool *pool,
75                      unsigned item_size,
76                      unsigned num_blocks,
77                      enum util_slab_threading threading);
78
79void util_slab_destroy(struct util_slab_mempool *pool);
80
81void 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