search-view: start searching after 3 characters and 500ms

Add timeout and minimum string length (3 characters) before triggering
searching routine.

App freezes and lags for a few seconds once one starts typing due to
the huge amount of matched events.

Search will be triggered only if passed time since last inserted
charactere is at least 500ms and three characteres have been entered.
If length is already >= 3 but user keeps typing in a quick fashion
(i.e. faster than 500ms per charactere) pre-scheduled search routine
(timeout from the last inserted char) is cancelled and a new one
is created.

https://bugzilla.gnome.org/show_bug.cgi?id=775549

src/gcal-search-view.c

@@ -52,6 +52,7 @@ struct _GcalSearchView
   gchar          *field;
   gchar          *query;
   time_t          current_utc_date;
+  guint           search_timeout_id;
 
   /* property */
   icaltimetype   *date;
@@ -101,6 +102,8 @@ static GtkWidget*     make_row_for_event                        (GcalSearchView
 
 static void           update_view                               (GcalSearchView       *view);
 
+static gboolean       gcal_search_view_do_search                (gpointer             user_data);
+
 /* prefixed */
 static void           gcal_data_model_subscriber_interface_init (ECalDataModelSubscriberInterface *iface);
 
@@ -415,6 +418,55 @@ update_view (GcalSearchView *view)
   view->no_results_timeout_id = g_timeout_add (NO_RESULT_TIMEOUT, (GSourceFunc) show_no_results_page, view);
 }
 
+/**
+ * gcal_search_view_do_search:
+ * @view: a #GcalSearchView instance.
+ *
+ * Called after 500ms since last typed character
+ * in the search field.
+ *
+ * Returns: @G_SOURCE_REMOVE
+ */
+static gboolean
+gcal_search_view_do_search (gpointer user_data)
+{
+  GcalSearchView *view;
+  gchar *search_query;
+
+  view = GCAL_SEARCH_VIEW (user_data);
+
+  search_query = g_strdup_printf ("(contains? \"%s\" \"%s\")",
+                                             view->field ? view->field : "summary",
+                                             view->query ? view->query : "");
+
+  if (!view->subscribed)
+        {
+          g_autoptr (GDateTime) now, start, end;
+
+          now = g_date_time_new_now_local ();
+          start = g_date_time_add_years (now, -5);
+          end = g_date_time_add_years (now, 5);
+
+          gcal_manager_set_search_subscriber (view->manager, E_CAL_DATA_MODEL_SUBSCRIBER (view),
+                                              g_date_time_to_unix (start),
+                                              g_date_time_to_unix (end));
+
+          /* Mark the view as subscribed */
+          view->subscribed = TRUE;
+        }
+
+      /* update internal current time_t */
+      view->current_utc_date = time (NULL);
+
+      gcal_manager_set_query (view->manager, search_query);
+
+      view->search_timeout_id = 0;
+      g_free (search_query);
+
+
+  return G_SOURCE_REMOVE;
+}
+
 static void
 gcal_search_view_class_init (GcalSearchViewClass *klass)
 {
@@ -719,6 +771,7 @@ gcal_search_view_set_time_format (GcalSearchView *view,
   view->format_24h = format_24h;
 }
 
+
 /**
  * gcal_search_view_set_search:
  * @view: a #GcalSearchView instance
@@ -737,38 +790,16 @@ gcal_search_view_search (GcalSearchView *view,
   g_clear_pointer (&view->query, g_free);
   g_clear_pointer (&view->field, g_free);
 
-  /* Only perform search on valid non-empty strings */
-  if (query && g_utf8_strlen (query, -1) > 0)
-    {
-      gchar *search_query = g_strdup_printf ("(contains? \"%s\" \"%s\")",
-                                             field ? field : "summary",
-                                             query ? query : "");
+  if (view->search_timeout_id != 0)
+    g_source_remove (view->search_timeout_id);
 
+
+  /* Only perform search on valid non-empty strings */
+  if (query && g_utf8_strlen (query, -1) >= 3)
+    {
       view->query = g_strdup (query);
       view->field = g_strdup (field);
-
-      if (!view->subscribed)
-        {
-          g_autoptr (GDateTime) now, start, end;
-
-          now = g_date_time_new_now_local ();
-          start = g_date_time_add_years (now, -5);
-          end = g_date_time_add_years (now, 5);
-
-          gcal_manager_set_search_subscriber (view->manager, E_CAL_DATA_MODEL_SUBSCRIBER (view),
-                                              g_date_time_to_unix (start),
-                                              g_date_time_to_unix (end));
-
-          /* Mark the view as subscribed */
-          view->subscribed = TRUE;
-        }
-
-      /* update internal current time_t */
-      view->current_utc_date = time (NULL);
-
-      gcal_manager_set_query (view->manager, search_query);
-
-      g_free (search_query);
+      view->search_timeout_id = g_timeout_add (500, gcal_search_view_do_search, view);
     }
   else
     {

src/gcal-search-view.h

@@ -43,6 +43,7 @@ GtkWidget*     gcal_search_view_new              (void);
 void           gcal_search_view_connect          (GcalSearchView *search_view,
                                                   GcalManager    *manager);
 
+
 G_END_DECLS
 
 #endif /* __GCAL_SEARCH_VIEW_H__ */