[glib/new-gsettings] Add back memory backend that got removed, and update it

[Vincent Untz <vuntz src gnome org>]

commit d1664c0e3ca9514a7c7b10349f1ee12e5857f8f1
Author: Vincent Untz <vuntz gnome org>
Date:   Wed Apr 14 18:01:06 2010 -0400

    Add back memory backend that got removed, and update it
    
    It should work with the latest GSettingsBackend.

 gio/gmemorysettingsbackend.c |  361 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 361 insertions(+), 0 deletions(-)
---
diff --git a/gio/gmemorysettingsbackend.c b/gio/gmemorysettingsbackend.c
index 69ee729..245d235 100644
--- a/gio/gmemorysettingsbackend.c
+++ b/gio/gmemorysettingsbackend.c
@@ -7,3 +7,364 @@
 #include "gfilemonitor.h"
 
 #include "gmemorysettingsbackend.h"
+
+G_DEFINE_TYPE_WITH_CODE (GMemorySettingsBackend,
+                         g_memory_settings_backend,
+                         G_TYPE_SETTINGS_BACKEND,
+                         g_io_extension_point_implement (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
+                                                         g_define_type_id, "memory", 0))
+
+struct _GMemorySettingsBackendPrivate
+{
+  GHashTable   *table;
+  GKeyFile     *keyfile;
+  gchar        *keyfile_path;
+  gchar        *keyfile_checksum;
+  GFileMonitor *keyfile_monitor;
+};
+
+static GVariant *
+g_memory_settings_backend_read (GSettingsBackend   *backend,
+                                const gchar        *key,
+                                const GVariantType *expected_type)
+{
+  GVariant *value;
+
+  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);
+
+  value = g_hash_table_lookup (memory->priv->table, key);
+
+  if (value != NULL)
+    g_variant_ref (value);
+
+  return value;
+}
+
+static gboolean
+g_memory_settings_backend_write_one (const gchar            *key,
+                                     GVariant               *value,
+                                     GMemorySettingsBackend *memory)
+{
+  const gchar *slash;
+  const gchar *base_key;
+  gchar       *path;
+
+  g_hash_table_replace (memory->priv->table,
+                        g_strdup (key), g_variant_ref (value));
+
+  slash = strrchr (key, '/');
+  base_key = (slash + 1);
+  path = g_strndup (key, slash - key);
+
+  g_key_file_set_string (memory->priv->keyfile,
+                         path, base_key, g_variant_print (value, FALSE));
+
+  g_free (path);
+
+  return FALSE;
+}
+
+static void
+g_memory_settings_backend_keyfile_write (GMemorySettingsBackend *memory)
+{
+  gchar *dirname;
+  gchar *contents;
+  gsize  length;
+  GFile *file;
+
+  dirname = g_path_get_dirname (memory->priv->keyfile_path);
+  if (!g_file_test (dirname, G_FILE_TEST_IS_DIR))
+    g_mkdir_with_parents (dirname, 0700);
+  g_free (dirname);
+
+  contents = g_key_file_to_data (memory->priv->keyfile, &length, NULL);
+
+  file = g_file_new_for_path (memory->priv->keyfile_path);
+  g_file_replace_contents (file, contents, length,
+                           NULL, FALSE, G_FILE_CREATE_REPLACE_DESTINATION,
+                           NULL, NULL, NULL);
+  g_object_unref (file);
+
+  g_free (memory->priv->keyfile_checksum);
+  memory->priv->keyfile_checksum = g_compute_checksum_for_string (G_CHECKSUM_SHA256, contents, length);
+
+  g_free (contents);
+}
+
+static void
+g_memory_settings_backend_write (GSettingsBackend *backend,
+                                 const gchar      *key,
+                                 GVariant         *value,
+                                 gpointer          origin_tag)
+{
+  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);
+
+  g_memory_settings_backend_write_one (key, value, memory);
+  g_memory_settings_backend_keyfile_write (memory);
+
+  g_settings_backend_changed (backend, key, origin_tag);
+}
+
+static void
+g_memory_settings_backend_write_keys (GSettingsBackend *backend,
+                                      GTree            *tree,
+                                      gpointer          origin_tag)
+{
+  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (backend);
+
+  g_tree_foreach (tree, (GTraverseFunc) g_memory_settings_backend_write_one, backend);
+  g_memory_settings_backend_keyfile_write (memory);
+
+  g_settings_backend_changed_tree (backend, tree, origin_tag);
+}
+
+static gboolean
+g_memory_settings_backend_get_writable (GSettingsBackend *backend,
+                                        const gchar      *name)
+{
+  return TRUE;
+}
+
+static gboolean
+g_memory_settings_backend_supports_context (const gchar *context)
+{
+  return TRUE;
+}
+
+static void
+g_memory_settings_backend_keyfile_reload (GMemorySettingsBackend *memory)
+{
+  gchar       *contents = NULL;
+  gsize        length = 0;
+  gchar       *new_checksum;
+  GHashTable  *loaded_keys;
+  GPtrArray   *changed_array;
+  gchar      **groups = NULL;
+  gsize        groups_nb = 0;
+  int          i;
+  GList       *keys_l = NULL;
+  GList       *l;
+
+  if (!g_file_get_contents (memory->priv->keyfile_path,
+                            &contents, &length, NULL))
+    {
+      contents = g_strdup ("");
+      length = 0;
+    }
+
+  new_checksum = g_compute_checksum_for_string (G_CHECKSUM_SHA256, contents, length);
+
+  if (g_strcmp0 (memory->priv->keyfile_checksum, new_checksum) == 0) {
+    g_free (new_checksum);
+    return;
+  }
+
+  if (memory->priv->keyfile_checksum != NULL)
+    g_free (memory->priv->keyfile_checksum);
+  memory->priv->keyfile_checksum = new_checksum;
+
+  if (memory->priv->keyfile != NULL)
+    g_key_file_free (memory->priv->keyfile);
+
+  memory->priv->keyfile = g_key_file_new ();
+
+  /* we just silently ignore errors: there's not much we can do about them */
+  if (length > 0)
+    g_key_file_load_from_data (memory->priv->keyfile, contents, length,
+                               G_KEY_FILE_KEEP_COMMENTS|G_KEY_FILE_KEEP_TRANSLATIONS, NULL);
+
+  loaded_keys = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+  changed_array = g_ptr_array_new_with_free_func (g_free);
+
+  /* Load keys from the keyfile */
+  groups = g_key_file_get_groups (memory->priv->keyfile, &groups_nb);
+  for (i = 0; i < groups_nb; i++)
+    {
+      gchar **keys = NULL;
+      gsize   keys_nb = 0;
+      int     j;
+
+      keys = g_key_file_get_keys (memory->priv->keyfile, groups[i], &keys_nb, NULL);
+      if (keys == NULL)
+        continue;
+
+      for (j = 0; j < keys_nb; j++)
+        {
+          gchar    *value;
+          gchar    *full_key;
+          GVariant *old_variant;
+          GVariant *variant;
+
+          value = g_key_file_get_string (memory->priv->keyfile, groups[i], keys[j], NULL);
+          if (value == NULL)
+            continue;
+
+          variant = g_variant_new_parsed (value);
+          g_free (value);
+
+          if (variant == NULL)
+            continue;
+
+          full_key = g_strjoin ("", groups[i], keys[j], NULL),
+          g_hash_table_insert (loaded_keys, full_key, GINT_TO_POINTER(TRUE));
+
+          old_variant = g_hash_table_lookup (memory->priv->table, full_key);
+
+          if (old_variant == NULL || !g_variant_equal (old_variant, variant))
+            {
+              g_ptr_array_add (changed_array, g_strdup (full_key));
+              g_hash_table_replace (memory->priv->table,
+                                    g_strdup (full_key),
+                                    g_variant_ref_sink (variant));
+            }
+          else
+            g_variant_unref (variant);
+        }
+
+      g_strfreev (keys);
+    }
+  g_strfreev (groups);
+
+  /* Remove keys that were in the hashtable but not in the keyfile */
+  keys_l = g_hash_table_get_keys (memory->priv->table);
+  for (l = keys_l; l != NULL; l = l->next)
+    {
+      gchar *key = l->data;
+
+      if (g_hash_table_lookup_extended (loaded_keys, key, NULL, NULL))
+        continue;
+
+      g_ptr_array_add (changed_array, g_strdup (key));
+      g_hash_table_remove (memory->priv->table, key);
+    }
+  g_list_free (keys_l);
+
+  if (changed_array->len > 0)
+    {
+      /* the array has to be NULL-terminated */
+      g_ptr_array_add (changed_array, NULL);
+      g_settings_backend_keys_changed (G_SETTINGS_BACKEND (memory),
+                                       NULL,
+                                       (const gchar **) changed_array->pdata,
+                                       NULL);
+    }
+
+  g_hash_table_unref (loaded_keys);
+  g_ptr_array_free (changed_array, TRUE);
+}
+
+static void
+g_memory_settings_backend_keyfile_changed (GFileMonitor      *monitor,
+                                           GFile             *file,
+                                           GFile             *other_file,
+                                           GFileMonitorEvent  event_type,
+                                           gpointer           user_data)
+{
+  GMemorySettingsBackend *memory;
+
+  if (event_type != G_FILE_MONITOR_EVENT_CHANGED &&
+      event_type != G_FILE_MONITOR_EVENT_CREATED &&
+      event_type != G_FILE_MONITOR_EVENT_DELETED)
+    return;
+
+  memory = G_MEMORY_SETTINGS_BACKEND (user_data);
+  g_memory_settings_backend_keyfile_reload (memory);
+}
+
+static void
+g_memory_settings_backend_finalize (GObject *object)
+{
+  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (object);
+
+  g_hash_table_unref (memory->priv->table);
+  memory->priv->table = NULL;
+
+  g_key_file_free (memory->priv->keyfile);
+  memory->priv->keyfile = NULL;
+
+  g_free (memory->priv->keyfile_path);
+  memory->priv->keyfile_path = NULL;
+
+  g_free (memory->priv->keyfile_checksum);
+  memory->priv->keyfile_checksum = NULL;
+
+  g_file_monitor_cancel (memory->priv->keyfile_monitor);
+  g_object_unref (memory->priv->keyfile_monitor);
+  memory->priv->keyfile_monitor = NULL;
+
+  G_OBJECT_CLASS (g_memory_settings_backend_parent_class)
+    ->finalize (object);
+}
+
+static void
+g_memory_settings_backend_constructed (GObject *object)
+{
+  GMemorySettingsBackend *memory = G_MEMORY_SETTINGS_BACKEND (object);
+  const gchar            *envvar_path;
+  gchar                  *path;
+  gchar                  *context;
+  GFile                  *file;
+
+  envvar_path = g_getenv ("GSETTINGS_MEMORY_BACKEND_STORE");
+  if (envvar_path != NULL && envvar_path[0] != '\0')
+    path = g_strdup (envvar_path);
+  else
+    path = g_build_filename (g_get_user_config_dir (),
+                             "gsettings", "store", NULL);
+
+  context = NULL;
+  g_object_get (memory, "context", &context, NULL);
+  if (context)
+    {
+      memory->priv->keyfile_path = g_strdup_printf ("%s.%s", path, context);
+      g_free (context);
+      g_free (path);
+    }
+  else
+    memory->priv->keyfile_path = path;
+
+  file = g_file_new_for_path (memory->priv->keyfile_path);
+  memory->priv->keyfile_monitor = g_file_monitor_file (file, G_FILE_MONITOR_NONE, NULL, NULL);
+  g_signal_connect (memory->priv->keyfile_monitor, "changed",
+                    (GCallback)g_memory_settings_backend_keyfile_changed, memory);
+  g_object_unref (file);
+
+  g_memory_settings_backend_keyfile_reload (memory);
+}
+
+static void
+g_memory_settings_backend_init (GMemorySettingsBackend *memory)
+{
+  memory->priv = G_TYPE_INSTANCE_GET_PRIVATE (memory,
+                                              G_TYPE_MEMORY_SETTINGS_BACKEND,
+                                              GMemorySettingsBackendPrivate);
+  memory->priv->table =
+    g_hash_table_new_full (g_str_hash, g_str_equal, g_free,
+                           (GDestroyNotify) g_variant_unref);
+
+  memory->priv->keyfile = NULL;
+  memory->priv->keyfile_path = NULL;
+  memory->priv->keyfile_checksum = NULL;
+  memory->priv->keyfile_monitor = NULL;
+}
+
+static void
+g_memory_settings_backend_class_init (GMemorySettingsBackendClass *class)
+{
+  GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->constructed = g_memory_settings_backend_constructed;
+  object_class->finalize = g_memory_settings_backend_finalize;
+
+  backend_class->read = g_memory_settings_backend_read;
+  backend_class->write = g_memory_settings_backend_write;
+  backend_class->write_keys = g_memory_settings_backend_write_keys;
+  backend_class->get_writable = g_memory_settings_backend_get_writable;
+  /* No need to implement subscribed/unsubscribe: the only point would be to
+   * stop monitoring the file when there's no GSettings anymore, which is no
+   * big win. */
+  backend_class->supports_context = g_memory_settings_backend_supports_context;
+
+  g_type_class_add_private (class, sizeof (GMemorySettingsBackendPrivate));
+}