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/* Node caching
Copyright (C) 1997 Free Software Foundation, Inc.
Written by Miles Bader <address@hidden>
This file is part of the GNU Hurd.
The GNU Hurd 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, or (at
your option) any later version.
The GNU Hurd 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., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
#include <ncache.h>
#include <unistd.h>
#include <string.h>
#include <hurd/netfs.h>
#include <acpifs.h>
#include <netfs_impl.h>
/* Implementation of node caching functions */
/* Remove NN's node from its position in FS's node cache. */
void
node_unlink (struct node *node, struct acpifs *fs)
{
struct netnode *nn = node->nn;
if (nn->ncache_next)
nn->ncache_next->nn->ncache_prev = nn->ncache_prev;
if (nn->ncache_prev)
nn->ncache_prev->nn->ncache_next = nn->ncache_next;
if (fs->node_cache_mru == node)
fs->node_cache_mru = nn->ncache_next;
if (fs->node_cache_lru == node)
fs->node_cache_lru = nn->ncache_prev;
nn->ncache_next = 0;
nn->ncache_prev = 0;
fs->node_cache_len--;
}
/* Add NODE to the recently-used-node cache, which adds a reference to
prevent it from going away. NODE should be locked. */
void
node_cache (struct node *node)
{
struct netnode *nn = node->nn;
pthread_mutex_lock (&fs->node_cache_lock);
if (fs->node_cache_max > 0 || fs->node_cache_len > 0)
{
if (fs->node_cache_mru != node)
{
if (nn->ncache_next || nn->ncache_prev)
/* Node is already in the cache. */
node_unlink (node, fs);
else
/* Add a reference from the cache. */
netfs_nref (node);
nn->ncache_next = fs->node_cache_mru;
nn->ncache_prev = 0;
if (fs->node_cache_mru)
fs->node_cache_mru->nn->ncache_prev = node;
if (!fs->node_cache_lru)
fs->node_cache_lru = node;
fs->node_cache_mru = node;
fs->node_cache_len++;
}
/* Forget the least used nodes. */
while (fs->node_cache_len > fs->node_cache_max)
{
struct node *lru = fs->node_cache_lru;
node_unlink (lru, fs);
netfs_nrele (lru);
}
}
pthread_mutex_unlock (&fs->node_cache_lock);
}
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