PCI Arbiter

1 files changed, 90 insertions, 0 deletions

diff --git a/pci-arbiter/ncache.c b/pci-arbiter/ncache.c
new file mode 100644
index 00000000..6a513e37
--- /dev/null
+++ b/pci-arbiter/ncache.c
@@ -0,0 +1,90 @@
+/* Node caching
+
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   Written by Miles Bader <miles@gnu.org>
+   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 "pcifs.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 pcifs *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->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);
+	}
+    }
+
+  pthread_mutex_unlock (&fs->node_cache_lock);
+}