[dconf: 1/4] service: factor out gvdb read/write code

[Ryan Lortie <ryanl src gnome org>]

commit 12395df3d35426e05231e8401bd03fdded6cb7ab
Author: Ryan Lortie <desrt desrt ca>
Date:   Fri Nov 9 12:53:58 2012 -0500

    service: factor out gvdb read/write code
    
    Factor the code for reading and writing DConfChangeset databases to the
    gvdb file format out from dconf-writer.c.
    
    This will allow those functions to be used by other backend
    implementations that want to store things in gvdb format (like on NFS).

 service/Makefile.am        |    2 +
 service/dconf-gvdb-utils.c |  157 ++++++++++++++++++++++++++++++++++++++++++++
 service/dconf-gvdb-utils.h |   34 ++++++++++
 service/dconf-writer.c     |  152 +++---------------------------------------
 4 files changed, 204 insertions(+), 141 deletions(-)
---
diff --git a/service/Makefile.am b/service/Makefile.am
index 3f70ff2..5801b3f 100644
--- a/service/Makefile.am
+++ b/service/Makefile.am
@@ -15,6 +15,8 @@ dconf_service_SOURCES = \
 	$(BUILT_SOURCES)		\
 	dconf-blame.c			\
 	dconf-blame.h			\
+	dconf-gvdb-utils.c		\
+	dconf-gvdb-utils.h		\
 	dconf-service.c			\
 	dconf-service.h			\
 	dconf-writer.h			\
diff --git a/service/dconf-gvdb-utils.c b/service/dconf-gvdb-utils.c
new file mode 100644
index 0000000..4e93cc8
--- /dev/null
+++ b/service/dconf-gvdb-utils.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright  2010 Codethink Limited
+ * Copyright  2012 Canonical Limited
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Ryan Lortie <desrt desrt ca>
+ */
+
+#include "dconf-gvdb-utils.h"
+
+#include "../gvdb/gvdb-builder.h"
+#include "../gvdb/gvdb-reader.h"
+
+#include <string.h>
+
+DConfChangeset *
+dconf_gvdb_utils_read_file (const gchar  *filename,
+                            GError      **error)
+{
+  DConfChangeset *database;
+  GError *my_error = NULL;
+  GvdbTable *table;
+
+  table = gvdb_table_new (filename, FALSE, &my_error);
+
+  /* It is perfectly fine if the file does not exist -- then it's
+   * just empty.
+   */
+  if (g_error_matches (my_error, G_FILE_ERROR, G_FILE_ERROR_NOENT))
+    g_clear_error (&my_error);
+
+  /* Otherwise, we should report errors to prevent ourselves from
+   * overwriting the database in other situations...
+   */
+  if (my_error)
+    {
+      g_propagate_prefixed_error (error, my_error, "Cannot open dconf database: ");
+      return NULL;
+    }
+
+  /* Only allocate once we know we are in a non-error situation */
+  database = dconf_changeset_new_database (NULL);
+
+  /* Fill the table up with the initial state */
+  if (table != NULL)
+    {
+      gchar **names;
+      gint n_names;
+      gint i;
+
+      names = gvdb_table_get_names (table, &n_names);
+      for (i = 0; i < n_names; i++)
+        {
+          if (dconf_is_key (names[i], NULL))
+            {
+              GVariant *value;
+
+              value = gvdb_table_get_value (table, names[i]);
+
+              if (value != NULL)
+                {
+                  dconf_changeset_set (database, names[i], value);
+                  g_variant_unref (value);
+                }
+            }
+
+          g_free (names[i]);
+        }
+
+      gvdb_table_unref (table);
+      g_free (names);
+    }
+
+  return database;
+}
+
+static GvdbItem *
+dconf_gvdb_utils_get_parent (GHashTable  *table,
+                             const gchar *key)
+{
+  GvdbItem *grandparent, *parent;
+  gchar *parent_name;
+  gint len;
+
+  if (g_str_equal (key, "/"))
+    return NULL;
+
+  len = strlen (key);
+  if (key[len - 1] == '/')
+    len--;
+
+  while (key[len - 1] != '/')
+    len--;
+
+  parent_name = g_strndup (key, len);
+  parent = g_hash_table_lookup (table, parent_name);
+
+  if (parent == NULL)
+    {
+      parent = gvdb_hash_table_insert (table, parent_name);
+
+      grandparent = dconf_gvdb_utils_get_parent (table, parent_name);
+
+      if (grandparent != NULL)
+        gvdb_item_set_parent (parent, grandparent);
+    }
+
+  g_free (parent_name);
+
+  return parent;
+}
+
+static gboolean
+dconf_gvdb_utils_add_key (const gchar *path,
+                          GVariant    *value,
+                          gpointer     user_data)
+{
+  GHashTable *gvdb = user_data;
+  GvdbItem *item;
+
+  g_assert (g_hash_table_lookup (gvdb, path) == NULL);
+  item = gvdb_hash_table_insert (gvdb, path);
+  gvdb_item_set_parent (item, dconf_gvdb_utils_get_parent (gvdb, path));
+  gvdb_item_set_value (item, value);
+
+  return TRUE;
+}
+
+gboolean
+dconf_gvdb_utils_write_file (const gchar     *filename,
+                             DConfChangeset  *database,
+                             GError         **error)
+{
+  GHashTable *gvdb;
+  gboolean success;
+
+  gvdb = gvdb_hash_table_new (NULL, NULL);
+  dconf_changeset_all (database, dconf_gvdb_utils_add_key, gvdb);
+  success = gvdb_table_write_contents (gvdb, filename, FALSE, error);
+  g_hash_table_unref (gvdb);
+
+  return success;
+}
diff --git a/service/dconf-gvdb-utils.h b/service/dconf-gvdb-utils.h
new file mode 100644
index 0000000..ff5d9fe
--- /dev/null
+++ b/service/dconf-gvdb-utils.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright  2010 Codethink Limited
+ * Copyright  2012 Canonical Limited
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Ryan Lortie <desrt desrt ca>
+ */
+
+#ifndef __dconf_gvdb_utils_h__
+#define __dconf_gvdb_utils_h__
+
+#include "../common/dconf-changeset.h"
+
+DConfChangeset *                dconf_gvdb_utils_read_file              (const gchar     *filename,
+                                                                         GError         **error);
+gboolean                        dconf_gvdb_utils_write_file             (const gchar     *filename,
+                                                                         DConfChangeset  *database,
+                                                                         GError         **error);
+
+#endif /* __dconf_gvdb_utils_h__ */
diff --git a/service/dconf-writer.c b/service/dconf-writer.c
index 7e9a539..b0b1015 100644
--- a/service/dconf-writer.c
+++ b/service/dconf-writer.c
@@ -1,5 +1,6 @@
 /*
  * Copyright  2010 Codethink Limited
+ * Copyright  2012 Canonical Limited
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -22,6 +23,8 @@
 #include "dconf-writer.h"
 
 #include "../shm/dconf-shm.h"
+#include "dconf-gvdb-utils.h"
+#include "dconf-generated.h"
 
 #include <stdlib.h>
 #include <unistd.h>
@@ -30,11 +33,6 @@
 #include <errno.h>
 #include <stdio.h>
 
-#include "dconf-generated.h"
-#include "../common/dconf-changeset.h"
-#include "../gvdb/gvdb-builder.h"
-#include "../gvdb/gvdb-reader.h"
-
 typedef struct
 {
   DConfDBusWriterSkeleton parent_instance;
@@ -76,62 +74,6 @@ static void dconf_writer_iface_init (DConfDBusWriterIface *iface);
 G_DEFINE_TYPE_WITH_CODE (DConfWriter, dconf_writer, DCONF_DBUS_TYPE_WRITER_SKELETON,
                          G_IMPLEMENT_INTERFACE (DCONF_DBUS_TYPE_WRITER, dconf_writer_iface_init))
 
-static GvdbItem *
-dconf_writer_get_parent (GHashTable  *table,
-                         const gchar *key)
-{
-  GvdbItem *grandparent, *parent;
-  gchar *parent_name;
-  gint len;
-
-  if (g_str_equal (key, "/"))
-    return NULL;
-
-  len = strlen (key);
-  if (key[len - 1] == '/')
-    len--;
-
-  while (key[len - 1] != '/')
-    len--;
-
-  parent_name = g_strndup (key, len);
-  parent = g_hash_table_lookup (table, parent_name);
-
-  if (parent == NULL)
-    {
-      parent = gvdb_hash_table_insert (table, parent_name);
-
-      grandparent = dconf_writer_get_parent (table, parent_name);
-
-      if (grandparent != NULL)
-        gvdb_item_set_parent (parent, grandparent);
-    }
-
-  g_free (parent_name);
-
-  return parent;
-}
-
-static GHashTable *
-dconf_writer_new_value_table (GHashTable *copy_from)
-{
-  GHashTable *table;
-
-  table = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_variant_unref);
-
-  if (copy_from)
-    {
-      GHashTableIter iter;
-      gpointer key, value;
-
-      g_hash_table_iter_init (&iter, copy_from);
-      while (g_hash_table_iter_next (&iter, &key, &value))
-        g_hash_table_insert (table, g_strdup (key), g_variant_ref (value));
-    }
-
-  return table;
-}
-
 static gchar *
 dconf_writer_get_tag (DConfWriter *writer)
 {
@@ -153,58 +95,10 @@ dconf_writer_real_begin (DConfWriter  *writer,
    */
   if (writer->commited_values == NULL)
     {
-      GError *my_error = NULL;
-      GvdbTable *table;
-
-      table = gvdb_table_new (writer->filename, FALSE, &my_error);
-
-      /* It is perfectly fine if the file does not exist -- then it's
-       * just empty.
-       */
-      if (g_error_matches (my_error, G_FILE_ERROR, G_FILE_ERROR_NOENT))
-        g_clear_error (&my_error);
-
-      /* Otherwise, we should report errors to prevent ourselves from
-       * overwriting the database in other situations...
-       */
-      if (my_error)
-        {
-          g_propagate_prefixed_error (error, my_error, "Cannot open dconf database: ");
-          return FALSE;
-        }
-
-      /* Only initialise once we know we are in a non-error situation */
-      writer->commited_values = dconf_changeset_new_database (NULL);
-
-      /* Fill the table up with the initial state */
-      if (table != NULL)
-        {
-          gchar **names;
-          gint n_names;
-          gint i;
-
-          names = gvdb_table_get_names (table, &n_names);
-          for (i = 0; i < n_names; i++)
-            {
-              if (dconf_is_key (names[i], NULL))
-                {
-                  GVariant *value;
-
-                  value = gvdb_table_get_value (table, names[i]);
-
-                  if (value != NULL)
-                    {
-                      dconf_changeset_set (writer->commited_values, names[i], value);
-                      g_variant_unref (value);
-                    }
-                }
-
-              g_free (names[i]);
-            }
-
-          gvdb_table_unref (table);
-          g_free (names);
-        }
+      writer->commited_values = dconf_gvdb_utils_read_file (writer->filename, error);
+
+      if (!writer->commited_values)
+        return FALSE;
     }
 
   writer->uncommited_values = dconf_changeset_new_database (writer->commited_values);
@@ -234,37 +128,13 @@ dconf_writer_real_change (DConfWriter    *writer,
 }
 
 static gboolean
-dconf_writer_add_to_gvdb (const gchar *path,
-                          GVariant    *value,
-                          gpointer     user_data)
-{
-  GHashTable *gvdb = user_data;
-  GvdbItem *item;
-
-  g_assert (g_hash_table_lookup (gvdb, path) == NULL);
-  item = gvdb_hash_table_insert (gvdb, path);
-  gvdb_item_set_parent (item, dconf_writer_get_parent (gvdb, path));
-  gvdb_item_set_value (item, value);
-
-  return TRUE;
-}
-
-static gboolean
 dconf_writer_real_commit (DConfWriter  *writer,
                           GError      **error)
 {
-  gboolean success;
-
-  {
-    GHashTable *gvdb;
-
-    gvdb = gvdb_hash_table_new (NULL, NULL);
-    dconf_changeset_all (writer->uncommited_values, dconf_writer_add_to_gvdb, gvdb);
-    success = gvdb_table_write_contents (gvdb, writer->filename, FALSE, error);
-    g_hash_table_unref (gvdb);
-  }
+  if (!dconf_gvdb_utils_write_file (writer->filename, writer->uncommited_values, error))
+    return FALSE;
 
-  if (success && writer->native)
+  if (writer->native)
     dconf_shm_flag (writer->name);
 
   if (writer->commited_values)
@@ -280,7 +150,7 @@ dconf_writer_real_commit (DConfWriter  *writer,
     writer->uncommited_changes = empty_queue;
   }
 
-  return success;
+  return TRUE;
 }
 
 static void