1 files changed, 83 insertions, 0 deletions
diff --git a/cache.h b/cache.h
new file mode 100644
index 000000000..2ec926b76
--- /dev/null
+++ b/cache.h
@@ -0,0 +1,83 @@
+/* tarfs - A GNU tar filesystem for the Hurd.
+   Copyright (C) 2002, Ludovic Courtès <ludo@type-z.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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+   USA */
+
+/*
+ * Nodes contents cache management.
+ */
+
+#ifndef __CACHE_H__
+#define __CACHE_H__
+
+#include <stdlib.h>
+#include <error.h>
+#include <hurd/netfs.h>
+#include <hurd/store.h>
+
+/* Size of a cache block.  */
+#define CACHE_BLOCK_SIZE_LOG2  10
+#define CACHE_BLOCK_SIZE  (1 << CACHE_BLOCK_SIZE_LOG2)
+
+/* Cache data accessor */
+#define CACHE_INFO(Node, Field) \
+  (NODE_INFO(Node)->cache. Field)
+
+/* Nodes contents cache */
+struct cache
+{
+  /* Vector of cache blocks */
+  char **blocks;
+
+  /* Size of BLOCKS */
+  size_t size;
+
+  /* Lock of this cache */
+  struct mutex lock;
+};
+
+/* Initializes the cache backend.  READ is the method that will be called
+   when data needs to be read from a node.  */
+extern void cache_init (error_t (* read) (struct node *node, off_t offset,
+					  size_t howmuch,
+					  size_t *actually_read, void *data));
+
+/* Create a cache for node NODE.  */
+extern error_t cache_create (struct node *node);
+
+/* Free NODE's cache.  */
+extern error_t cache_free (struct node *node);
+
+/* Read at most AMOUNT bytes from NODE at OFFSET into BUF.
+   Returns the amount of data actually read in LEN.  */
+extern error_t cache_read (struct node *node, off_t offset,
+			   size_t amount, void *buf, size_t *len);
+
+/* Writes at most LEN bytes from NODE at OFFSET into BUF.
+   Returns the amount of data actually written in AMOUNT.  */
+extern error_t cache_write (struct node *node, off_t offset,
+			    void *data, size_t len, size_t *amount);
+
+/* Sets the size of NODE and reduce/grow its cache.  */
+extern error_t cache_set_size (struct node *node, size_t size);
+
+/* Cache AMOUNT bytes of NODE.  */
+extern error_t cache_cache (struct node *node, size_t amount);
+
+/* Returns non-zero if NODE is synchronized (ie. not cached).  */
+extern int cache_synced (struct node *node);
+
+#endif /* cache.h */