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/* cairo - a vector graphics library with display and print output
* Copyright © 2009 Chris Wilson
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
* The Original Code is the cairo graphics library.
* The Initial Developer of the Original Code is University of Southern
* California.
* Contributor(s):
* Chris Wilson <>
#include "cairoint.h"
#include "cairo-atomic-private.h"
/* Keep a stash of recently freed clip_paths, since we need to
* reallocate them frequently.
typedef struct {
void *pool[MAX_FREED_POOL_SIZE];
int top;
} freed_pool_t;
static cairo_always_inline void *
_atomic_fetch (void **slot)
void *ptr;
do {
ptr = _cairo_atomic_ptr_get (slot);
} while (! _cairo_atomic_ptr_cmpxchg (slot, ptr, NULL));
return ptr;
static cairo_always_inline cairo_bool_t
_atomic_store (void **slot, void *ptr)
return _cairo_atomic_ptr_cmpxchg (slot, NULL, ptr);
cairo_private void *
_freed_pool_get_search (freed_pool_t *pool);
static inline void *
_freed_pool_get (freed_pool_t *pool)
void *ptr;
int i;
i = pool->top - 1;
if (i < 0)
i = 0;
ptr = _atomic_fetch (&pool->pool[i]);
if (likely (ptr != NULL)) {
pool->top = i;
return ptr;
/* either empty or contended */
return _freed_pool_get_search (pool);
cairo_private void
_freed_pool_put_search (freed_pool_t *pool, void *ptr);
static inline void
_freed_pool_put (freed_pool_t *pool, void *ptr)
int i;
i = pool->top;
if (likely (i < ARRAY_LENGTH (pool->pool) &&
_atomic_store (&pool->pool[i], ptr)))
pool->top = i + 1;
/* either full or contended */
_freed_pool_put_search (pool, ptr);
cairo_private void
_freed_pool_reset (freed_pool_t *pool);
#define HAS_FREED_POOL 1
/* A warning about an unused freed-pool in a build without atomics
* enabled usually indicates a missing _freed_pool_reset() in the
* static reset function */
typedef int freed_pool_t;
#define _freed_pool_get(pool) NULL
#define _freed_pool_put(pool, ptr) free(ptr)
#define _freed_pool_reset(ptr)