120 lines
2.9 KiB
C
120 lines
2.9 KiB
C
|
/*
|
||
|
|
mrucache.h - most recent used cache
|
||
|
|
|
||
|
|
Copyright (C) Lumiera.org
|
||
|
|
2008, Christian Thaeter <ct@pipapo.org>
|
||
|
|
|
||
|
|
This program is free software; you can redistribute it and/or
|
||
|
|
modify it under the terms of the GNU General Public License as
|
||
|
|
published by the Free Software Foundation; either version 2 of the
|
||
|
|
License, or (at your option) any later version.
|
||
|
|
|
||
|
|
This program is distributed in the hope that it will be useful,
|
||
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
GNU General Public License for more details.
|
||
|
|
|
||
|
|
You should have received a copy of the GNU General Public License
|
||
|
|
along with this program; if not, write to the Free Software
|
||
|
|
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef LUMIERA_CACHE_H
|
||
|
|
#define LUMIERA_CACHE_H
|
||
|
|
|
||
|
|
#include "lib/llist.h"
|
||
|
|
|
||
|
|
#include <nobug.h>
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @file Most recent used cache
|
||
|
|
* Elements (addressed by a LList node) are either in the cache and thereby subject of aging
|
||
|
|
* or checked out under control of the user.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Callback function used to destruct/cleanup aged elements.
|
||
|
|
* shall clean the element sufficiently up to be ready for being freed or reused
|
||
|
|
* @param node the llist node used to link cache elements (will be empty at call)
|
||
|
|
* @return pointer to the begin of the element
|
||
|
|
*/
|
||
|
|
typedef void* (*lumiera_cache_destructor_fn)(LList node);
|
||
|
|
|
||
|
|
struct lumiera_mrucache_struct
|
||
|
|
{
|
||
|
|
llist cache_list;
|
||
|
|
size_t cached;
|
||
|
|
lumiera_cache_destructor_fn destructor_cb;
|
||
|
|
};
|
||
|
|
typedef struct lumiera_mrucache_struct lumiera_mrucache;
|
||
|
|
typedef lumiera_mrucache* LumieraMruCache;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Initialize a mrucache
|
||
|
|
*/
|
||
|
|
LumieraMruCache
|
||
|
|
lumiera_mrucache_init (LumieraMruCache self, lumiera_cache_destructor_fn destructor_cb);
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Destroy a mrucache
|
||
|
|
*/
|
||
|
|
LumieraMruCache
|
||
|
|
lumiera_mrucache_destroy (LumieraMruCache self);
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* add an element to a mrucache
|
||
|
|
*/
|
||
|
|
static inline void
|
||
|
|
lumiera_mrucache_add (LumieraMruCache self, LList node)
|
||
|
|
{
|
||
|
|
REQUIRE (self);
|
||
|
|
REQUIRE (node && llist_is_empty (node));
|
||
|
|
llist_insert_head (&self->cache_list, node);
|
||
|
|
++self->cached;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Remove an element from a mrucache.
|
||
|
|
*/
|
||
|
|
static inline void
|
||
|
|
lumiera_mrucache_remove (LumieraMruCache self, LList node)
|
||
|
|
{
|
||
|
|
REQUIRE (self);
|
||
|
|
REQUIRE (node && llist_is_member (&self->cache_list, node)); /* speedup loop warning :P, this check is costly */
|
||
|
|
llist_unlink (node);
|
||
|
|
--self->cached;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* destroy the oldest element and return a pointer to it for reuse.
|
||
|
|
*/
|
||
|
|
static inline void*
|
||
|
|
lumiera_mrucache_pop (LumieraMruCache self)
|
||
|
|
{
|
||
|
|
REQUIRE (self);
|
||
|
|
if (llist_is_empty (&self->cache_list))
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
LList node = llist_tail (&self->cache_list);
|
||
|
|
llist_unlink (node);
|
||
|
|
--self->cached;
|
||
|
|
|
||
|
|
if (self->destructor_cb)
|
||
|
|
return self->destructor_cb (node);
|
||
|
|
else
|
||
|
|
return node;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* destroy and free the nelem oldest elements
|
||
|
|
*/
|
||
|
|
void
|
||
|
|
lumiera_mrucache_age (LumieraMruCache self, size_t nelem);
|
||
|
|
|
||
|
|
|
||
|
|
#endif
|