Line data    Source code

       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             : #if HAS_ATOMIC_OPS
      44             : /* Keep a stash of recently freed clip_paths, since we need to
      45             :  * reallocate them frequently.
      46             :  */
      47             : #define MAX_FREED_POOL_SIZE 4
      48             : typedef struct {
      49             :     void *pool[MAX_FREED_POOL_SIZE];
      50             :     cairo_atomic_int_t top;
      51             : } freed_pool_t;
      52             : 
      53             : static cairo_always_inline void *
      54             : _atomic_fetch (void **slot)
      55             : {
      56             :     void *ptr;
      57             : 
      58             :     do {
      59           0 :         ptr = _cairo_atomic_ptr_get (slot);
      60           0 :     } while (! _cairo_atomic_ptr_cmpxchg (slot, ptr, NULL));
      61             : 
      62           0 :     return ptr;
      63             : }
      64             : 
      65             : static cairo_always_inline cairo_bool_t
      66             : _atomic_store (void **slot, void *ptr)
      67             : {
      68           0 :     return _cairo_atomic_ptr_cmpxchg (slot, NULL, ptr);
      69             : }
      70             : 
      71             : cairo_private void *
      72             : _freed_pool_get_search (freed_pool_t *pool);
      73             : 
      74             : static inline void *
      75           0 : _freed_pool_get (freed_pool_t *pool)
      76             : {
      77             :     void *ptr;
      78             :     int i;
      79             : 
      80           0 :     i = _cairo_atomic_int_get_relaxed (&pool->top) - 1;
      81           0 :     if (i < 0)
      82           0 :         i = 0;
      83             : 
      84           0 :     ptr = _atomic_fetch (&pool->pool[i]);
      85           0 :     if (likely (ptr != NULL)) {
      86           0 :         _cairo_atomic_int_set_relaxed (&pool->top, i);
      87           0 :         return ptr;
      88             :     }
      89             : 
      90             :     /* either empty or contended */
      91           0 :     return _freed_pool_get_search (pool);
      92             : }
      93             : 
      94             : cairo_private void
      95             : _freed_pool_put_search (freed_pool_t *pool, void *ptr);
      96             : 
      97             : static inline void
      98           0 : _freed_pool_put (freed_pool_t *pool, void *ptr)
      99             : {
     100             :     int i;
     101             : 
     102           0 :     i = _cairo_atomic_int_get_relaxed (&pool->top);
     103           0 :     if (likely (i < ARRAY_LENGTH (pool->pool) &&
     104             :                 _atomic_store (&pool->pool[i], ptr)))
     105             :     {
     106           0 :         _cairo_atomic_int_set_relaxed (&pool->top, i + 1);
     107           0 :         return;
     108             :     }
     109             : 
     110             :     /* either full or contended */
     111           0 :     _freed_pool_put_search (pool, ptr);
     112             : }
     113             : 
     114             : cairo_private void
     115             : _freed_pool_reset (freed_pool_t *pool);
     116             : 
     117             : #define HAS_FREED_POOL 1
     118             : 
     119             : #else
     120             : 
     121             : typedef int freed_pool_t;
     122             : 
     123             : #define _freed_pool_get(pool) NULL
     124             : #define _freed_pool_put(pool, ptr) free(ptr)
     125             : #define _freed_pool_reset(ptr)
     126             : 
     127             : #endif
     128             : 
     129             : #endif /* CAIRO_FREED_POOL_PRIVATE_H */