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14952 fschmid 1
/* cairo - a vector graphics library with display and print output
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 *
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 * Copyright © 2004 Red Hat, Inc.
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 * Copyright © 2005 Red Hat, Inc.
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it either under the terms of the GNU Lesser General Public
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 * License version 2.1 as published by the Free Software Foundation
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 * (the "LGPL") or, at your option, under the terms of the Mozilla
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 * Public License Version 1.1 (the "MPL"). If you do not alter this
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 * notice, a recipient may use your version of this file under either
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 * the MPL or the LGPL.
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 *
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 * You should have received a copy of the LGPL along with this library
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 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 * You should have received a copy of the MPL along with this library
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 * in the file COPYING-MPL-1.1
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 *
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 * The contents of this file are subject to the Mozilla Public License
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 * Version 1.1 (the "License"); you may not use this file except in
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 * compliance with the License. You may obtain a copy of the License at
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 * http://www.mozilla.org/MPL/
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 *
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 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
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 * the specific language governing rights and limitations.
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 *
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 * The Original Code is the cairo graphics library.
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 *
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 * The Initial Developer of the Original Code is Red Hat, Inc.
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 *
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 * Contributor(s):
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 *      Keith Packard <keithp@keithp.com>
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 *      Graydon Hoare <graydon@redhat.com>
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 *      Carl Worth <cworth@cworth.org>
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 */
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#ifndef CAIRO_CACHE_PRIVATE_H
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#define CAIRO_CACHE_PRIVATE_H
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#include "cairo-compiler-private.h"
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#include "cairo-types-private.h"
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/**
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 * cairo_cache_entry_t:
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 *
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 * A #cairo_cache_entry_t contains both a key and a value for
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 * #cairo_cache_t. User-derived types for #cairo_cache_entry_t must
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 * have a #cairo_cache_entry_t as their first field. For example:
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 *
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 *      typedef _my_entry {
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 *          cairo_cache_entry_t base;
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 *          ... Remainder of key and value fields here ..
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 *      } my_entry_t;
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 *
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 * which then allows a pointer to my_entry_t to be passed to any of
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 * the #cairo_cache_t functions as follows without requiring a cast:
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 *
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 *      _cairo_cache_insert (cache, &my_entry->base, size);
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 *
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 * IMPORTANT: The caller is responsible for initializing
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 * my_entry->base.hash with a hash code derived from the key.  The
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 * essential property of the hash code is that keys_equal must never
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 * return %TRUE for two keys that have different hashes. The best hash
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 * code will reduce the frequency of two keys with the same code for
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 * which keys_equal returns %FALSE.
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 *
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 * The user must also initialize my_entry->base.size to indicate
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 * the size of the current entry. What units to use for size is
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 * entirely up to the caller, (though the same units must be used for
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 * the max_size parameter passed to _cairo_cache_create()). If all
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 * entries are close to the same size, the simplest thing to do is to
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 * just use units of "entries", (eg. set size==1 in all entries and
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 * set max_size to the number of entries which you want to be saved
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 * in the cache).
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 *
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 * Which parts of the entry make up the "key" and which part make up
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 * the value are entirely up to the caller, (as determined by the
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 * computation going into base.hash as well as the keys_equal
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 * function). A few of the #cairo_cache_t functions accept an entry which
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 * will be used exclusively as a "key", (indicated by a parameter name
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 * of key). In these cases, the value-related fields of the entry need
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 * not be initialized if so desired.
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 **/
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typedef struct _cairo_cache_entry {
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    unsigned long hash;
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    unsigned long size;
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} cairo_cache_entry_t;
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typedef cairo_bool_t (*cairo_cache_predicate_func_t) (const void *entry);
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struct _cairo_cache {
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    cairo_hash_table_t *hash_table;
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    cairo_cache_predicate_func_t predicate;
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    cairo_destroy_func_t entry_destroy;
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    unsigned long max_size;
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    unsigned long size;
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    int freeze_count;
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};
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typedef cairo_bool_t
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(*cairo_cache_keys_equal_func_t) (const void *key_a, const void *key_b);
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typedef void
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(*cairo_cache_callback_func_t) (void *entry,
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                                void *closure);
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cairo_private cairo_status_t
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_cairo_cache_init (cairo_cache_t *cache,
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                   cairo_cache_keys_equal_func_t keys_equal,
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                   cairo_cache_predicate_func_t  predicate,
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                   cairo_destroy_func_t    entry_destroy,
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                   unsigned long                   max_size);
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cairo_private void
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_cairo_cache_fini (cairo_cache_t *cache);
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cairo_private void
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_cairo_cache_freeze (cairo_cache_t *cache);
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cairo_private void
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_cairo_cache_thaw (cairo_cache_t *cache);
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cairo_private void *
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_cairo_cache_lookup (cairo_cache_t        *cache,
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                     cairo_cache_entry_t  *key);
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cairo_private cairo_status_t
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_cairo_cache_insert (cairo_cache_t       *cache,
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                     cairo_cache_entry_t *entry);
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cairo_private void
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_cairo_cache_remove (cairo_cache_t       *cache,
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                     cairo_cache_entry_t *entry);
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cairo_private void
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_cairo_cache_foreach (cairo_cache_t              *cache,
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                      cairo_cache_callback_func_t cache_callback,
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                      void                       *closure);
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#endif