Cache provider, for caching a remote store locally. This is not done yet.

svn path=/trunk/; revision=5206

1 files changed, 255 insertions, 0 deletions

diff --git a/camel/providers/cache/camel-cache-map.c b/camel/providers/cache/camel-cache-map.c
new file mode 100644
index 0000000000..d3cece6f60
--- /dev/null
+++ b/camel/providers/cache/camel-cache-map.c
@@ -0,0 +1,255 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+/* camel-cache-map.c : functions for a local<->remote uid map */
+
+/* 
+ * Authors:
+ *   Dan Winship <danw@helixcode.com>
+ *
+ * Copyright (C) 2000 Helix Code, Inc. (www.helixcode.com)
+ *
+ * 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
+ */
+
+#include "camel-cache-map.h"
+#include <camel/camel-exception.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+/**
+ * camel_cache_map_new:
+ *
+ * Return value: a new CamelCacheMap
+ **/
+CamelCacheMap *
+camel_cache_map_new (void)
+{
+	CamelCacheMap *map = g_new (CamelCacheMap, 1);
+
+	map->l2r = g_hash_table_new (g_str_hash, g_str_equal);
+	map->r2l = g_hash_table_new (g_str_hash, g_str_equal);
+
+	return map;
+}
+
+static void
+free_mapping (gpointer key, gpointer value, gpointer data)
+{
+	g_free (key);
+	g_free (data);
+}
+
+/**
+ * camel_cache_map_destroy:
+ * @map: a CamelCacheMap
+ *
+ * Frees @map and all of the data stored in it.
+ **/
+void
+camel_cache_map_destroy (CamelCacheMap *map)
+{
+	g_hash_table_foreach (map->l2r, free_mapping, NULL);
+	g_hash_table_destroy (map->l2r);
+	g_hash_table_destroy (map->r2l);
+	g_free (map);
+}
+
+/**
+ * camel_cache_map_add:
+ * @map: a CamelCacheMap
+ * @luid: the local uid
+ * @ruid: the remote uid
+ *
+ * Adds a mapping between @luid and @ruid. If either already exists
+ * in the map, this may leak memory and result in incorrect map entries.
+ * Use camel_cache_map_update() in that case instead.
+ **/
+void
+camel_cache_map_add (CamelCacheMap *map, const char *luid, const char *ruid)
+{
+	char *map_luid = g_strdup (luid);
+	char *map_ruid = g_strdup (ruid);
+
+	g_hash_table_insert (map->l2r, map_luid, map_ruid);
+	g_hash_table_insert (map->r2l, map_ruid, map_luid);
+}
+
+/**
+ * camel_cache_map_remove:
+ * @map: a CamelCacheMap
+ * @luid: the local uid
+ * @ruid: the remote uid
+ *
+ * Removes the mapping between @luid and @ruid. Either (but not both)
+ * of the uids can be %NULL if they are not both known.
+ **/
+void
+camel_cache_map_remove (CamelCacheMap *map, const char *luid, const char *ruid)
+{
+	gpointer map_luid, map_ruid;
+
+	if ((luid && g_hash_table_lookup_extended (map->l2r, luid,
+						   &map_luid, &map_ruid)) ||
+	    (ruid && g_hash_table_lookup_extended (map->r2l, ruid,
+						  &map_luid, &map_ruid))) {
+		g_hash_table_remove (map->l2r, map_luid);
+		g_hash_table_remove (map->r2l, map_ruid);
+		g_free (map_luid);
+		g_free (map_ruid);
+	}
+}
+
+/**
+ * camel_cache_map_update:
+ * @map: a CamelCacheMap
+ * @luid: the local uid
+ * @ruid: the remote uid
+ *
+ * Updates the mappings to associate @luid with @ruid, clearing any
+ * previous mappings for both of them.
+ **/
+void
+camel_cache_map_update (CamelCacheMap *map, const char *luid, const char *ruid)
+{
+	camel_cache_map_remove (map, luid, ruid);
+	camel_cache_map_add (map, luid, ruid);
+}
+
+/**
+ * camel_cache_map_get_local
+ * @map: a CamelCacheMap
+ * @ruid: the remote uid
+ *
+ * Return value: the corresponding local uid, or %NULL
+ **/
+const char *
+camel_cache_map_get_local (CamelCacheMap *map, const char *ruid)
+{
+	return g_hash_table_lookup (map->r2l, ruid);
+}
+
+/**
+ * camel_cache_map_get_remote
+ * @map: a CamelCacheMap
+ * @luid: the local uid
+ *
+ * Return value: the corresponding remote uid, or %NULL
+ **/
+const char *
+camel_cache_map_get_remote (CamelCacheMap *map, const char *luid)
+{
+	return g_hash_table_lookup (map->l2r, luid);
+}
+
+
+
+static void
+write_mapping (gpointer key, gpointer value, gpointer user_data)
+{
+	int fd = *(int *)user_data;
+
+	/* FIXME: We assume the local UID has no ':'s in it. */
+	write (fd, key, strlen (key));
+	write (fd, ":", 1);
+	write (fd, value, strlen (value));
+	write (fd, "\n", 1);
+}
+
+/**
+ * camel_cache_map_write:
+ * @map: a CamelCacheMap
+ * @file: the filename to write the map to
+ * @ex: a CamelException
+ *
+ * Writes @map out to @file, setting @ex if something goes wrong.
+ **/
+void
+camel_cache_map_write (CamelCacheMap *map, const char *file,
+		       CamelException *ex)
+{
+	int fd;
+	char *tmpfile;
+
+	tmpfile = g_strdup_printf ("%s~", file);
+	fd = open (tmpfile, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
+	if (fd == -1) {
+		g_free (tmpfile);
+		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
+				      "Could not create cache map file: %s",
+				      g_strerror (errno));
+		return;
+	}
+
+	g_hash_table_foreach (map->l2r, write_mapping, &fd);
+
+	if (close (fd) == -1 ||
+	    rename (tmpfile, file) == -1) {
+		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
+				      "Could not save cache map file: %s",
+				      g_strerror (errno));
+		unlink (tmpfile);
+	}
+	g_free (tmpfile);
+}
+
+/**
+ * camel_cache_map_read:
+ * @map: a CamelCacheMap
+ * @file: the filename to read the map from
+ * @ex: a CamelException
+ *
+ * Reads @map from @file, setting @ex if something goes wrong. @map
+ * should be a freshly-created CamelCacheMap.
+ **/
+void
+camel_cache_map_read (CamelCacheMap *map, const char *file, CamelException *ex)
+{
+	FILE *f;
+	char buf[1024], *p, *q;
+
+	/* FIXME: lazy implementation. We could make this work with
+	 * lines longer than 1024 chars. :)
+	 */
+
+	f = fopen (file, "r");
+	if (!f) {
+		camel_exception_setv (ex, CAMEL_EXCEPTION_SYSTEM,
+				      "Could not open cache map file: %s",
+				      g_strerror (errno));
+		return;
+	}
+
+	while (fgets (buf, sizeof (buf), f)) {
+		p = strchr (buf, ':');
+		if (p)
+			q = strchr (buf, '\n');
+		if (!p || !q) {
+			camel_exception_set (ex, CAMEL_EXCEPTION_SYSTEM,
+					     "Bad cache file.");
+			return;
+		}
+		*p++ = *q = '\0';
+
+		/* Local uid at buf, remote at p. */
+		camel_cache_map_add (map, buf, p);
+	}
+
+	fclose (f);
+}