112 lines
3.6 KiB
C
112 lines
3.6 KiB
C
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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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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uintptr_t 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
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