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-rw-r--r--ftpfs/ncache.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/ftpfs/ncache.c b/ftpfs/ncache.c
new file mode 100644
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--- /dev/null
+++ b/ftpfs/ncache.c
@@ -0,0 +1,87 @@
+/* Node caching
+
+ Copyright (C) 1997 Free Software Foundation, Inc.
+ Written by Miles Bader <miles@gnu.ai.mit.edu>
+ 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 <unistd.h>
+#include <string.h>
+
+#include <hurd/netfs.h>
+
+#include "ftpfs.h"
+
+/* Remove NN's node from its position in FS's node cache. */
+static void
+node_unlink (struct node *node, struct ftpfs *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
+ftpfs_cache_node (struct node *node)
+{
+ struct netnode *nn = node->nn;
+ struct ftpfs *fs = nn->fs;
+
+ mutex_lock (&fs->node_cache_lock);
+
+ if (fs->params.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->params.node_cache_max)
+ {
+ struct node *lru = fs->node_cache_lru;
+ node_unlink (lru, fs);
+ netfs_nrele (lru);
+ }
+ }
+
+ mutex_unlock (&fs->node_cache_lock);
+}