source/libs/cairo/cairo-src/src/cairo-freed-pool-private.h

   1 /* cairo - a vector graphics library with display and print output
   2  *
   3  * Copyright © 2009 Chris Wilson
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it either under the terms of the GNU Lesser General Public
   7  * License version 2.1 as published by the Free Software Foundation
   8  * (the "LGPL") or, at your option, under the terms of the Mozilla
   9  * Public License Version 1.1 (the "MPL"). If you do not alter this
  10  * notice, a recipient may use your version of this file under either
  11  * the MPL or the LGPL.
  12  *
  13  * You should have received a copy of the LGPL along with this library
  14  * in the file COPYING-LGPL-2.1; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
  16  * You should have received a copy of the MPL along with this library
  17  * in the file COPYING-MPL-1.1
  18  *
  19  * The contents of this file are subject to the Mozilla Public License
  20  * Version 1.1 (the "License"); you may not use this file except in
  21  * compliance with the License. You may obtain a copy of the License at
  22  * http://www.mozilla.org/MPL/
  23  *
  24  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
  25  * OF ANY KIND, either express or implied. See the LGPL or the MPL for
  26  * the specific language governing rights and limitations.
  27  *
  28  * The Original Code is the cairo graphics library.
  29  *
  30  * The Initial Developer of the Original Code is University of Southern
  31  * California.
  32  *
  33  * Contributor(s):
  34  *      Chris Wilson <chris@chris-wilson.co.uk>
  35  */
  36
  37 #ifndef CAIRO_FREED_POOL_H
  38 #define CAIRO_FREED_POOL_H
  39
  40 #include "cairoint.h"
  41 #include "cairo-atomic-private.h"
  42
  43 CAIRO_BEGIN_DECLS
  44
  45 #define DISABLE_FREED_POOLS 0
  46
  47 #if HAS_ATOMIC_OPS && ! DISABLE_FREED_POOLS
  48 /* Keep a stash of recently freed clip_paths, since we need to
  49  * reallocate them frequently.
  50  */
  51 #define MAX_FREED_POOL_SIZE 16
  52 typedef struct {
  53     void *pool[MAX_FREED_POOL_SIZE];
  54     int top;
  55 } freed_pool_t;
  56
  57 static cairo_always_inline void *
  58 _atomic_fetch (void **slot)
  59 {
  60     void *ptr;
  61
  62     do {
  63         ptr = _cairo_atomic_ptr_get (slot);
  64     } while (! _cairo_atomic_ptr_cmpxchg (slot, ptr, NULL));
  65
  66     return ptr;
  67 }
  68
  69 static cairo_always_inline cairo_bool_t
  70 _atomic_store (void **slot, void *ptr)
  71 {
  72     return _cairo_atomic_ptr_cmpxchg (slot, NULL, ptr);
  73 }
  74
  75 cairo_private void *
  76 _freed_pool_get_search (freed_pool_t *pool);
  77
  78 static inline void *
  79 _freed_pool_get (freed_pool_t *pool)
  80 {
  81     void *ptr;
  82     int i;
  83
  84     i = pool->top - 1;
  85     if (i < 0)
  86         i = 0;
  87
  88     ptr = _atomic_fetch (&pool->pool[i]);
  89     if (likely (ptr != NULL)) {
  90         pool->top = i;
  91         return ptr;
  92     }
  93
  94     /* either empty or contended */
  95     return _freed_pool_get_search (pool);
  96 }
  97
  98 cairo_private void
  99 _freed_pool_put_search (freed_pool_t *pool, void *ptr);
 100
 101 static inline void
 102 _freed_pool_put (freed_pool_t *pool, void *ptr)
 103 {
 104     int i;
 105
 106     i = pool->top;
 107     if (likely (i < ARRAY_LENGTH (pool->pool) &&
 108                 _atomic_store (&pool->pool[i], ptr)))
 109     {
 110         pool->top = i + 1;
 111         return;
 112     }
 113
 114     /* either full or contended */
 115     _freed_pool_put_search (pool, ptr);
 116 }
 117
 118 cairo_private void
 119 _freed_pool_reset (freed_pool_t *pool);
 120
 121 #define HAS_FREED_POOL 1
 122
 123 #else
 124
 125 /* A warning about an unused freed-pool in a build without atomics
 126  * enabled usually indicates a missing _freed_pool_reset() in the
 127  * static reset function */
 128
 129 typedef int freed_pool_t;
 130
 131 #define _freed_pool_get(pool) NULL
 132 #define _freed_pool_put(pool, ptr) free(ptr)
 133 #define _freed_pool_reset(ptr)
 134
 135 #endif
 136
 137 CAIRO_END_DECLS
 138
 139 #endif /* CAIRO_FREED_POOL_PRIVATE_H */