[gnome-builder] gui: Cancel previous search when typing new text in search button

[Christian Hergert <chergert src gnome org>]

commit 7abab398d583b83feef68dd248ba1bd86b76bf4d
Author: vanadiae <vanadiae35 gmail com>
Date:   Mon Jun 28 18:19:26 2021 +0200

    gui: Cancel previous search when typing new text in search button
    
    Currently when having quite a few disk/CPU activity from another
    process (like compiling or just running `yes`), the global file
    search has a fair bit of latency when typing text, as the previous
    searchs are having a hard time with IO. So they tend to "pile up"
    when typing new characters, which means that there's a few seconds
    where the search results will change several times as search results
    start arriving.
    
    To prevent this sluggish search, this commit now cancels the
    previous search request in favor of a fresher one with the
    newly typed text.
    
    Also fixes a FIXME, where search errors are now reported in the
    messages pane instead of hidden in the logs.

 src/libide/gui/ide-search-button.c | 58 +++++++++++++++++++++++++++++++-------
 1 file changed, 48 insertions(+), 10 deletions(-)
---
diff --git a/src/libide/gui/ide-search-button.c b/src/libide/gui/ide-search-button.c
index dfcef08f1..4a2882241 100644
--- a/src/libide/gui/ide-search-button.c
+++ b/src/libide/gui/ide-search-button.c
@@ -35,6 +35,12 @@
 struct _IdeSearchButton
 {
   DzlSuggestionButton parent_instance;
+
+  // Used to cancel previous search if it was still running when a new character is entered,
+  // to avoid having the search become sluggish if typing quickly (as the suggestion entry
+  // reacts quickly but the search can be slow and they tend to pile up in the queue, slowing
+  // down even more).
+  GCancellable *cancellable;
 };
 
 static const DzlShortcutEntry shortcuts[] = {
@@ -64,8 +70,14 @@ search_entry_search_cb (GObject      *object,
 
   if (error != NULL)
     {
-      /* TODO: Elevate to workbench message once we have that capability */
-      g_warning ("%s", error->message);
+      if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        {
+          IdeWorkspace *workspace = IDE_WORKSPACE (gtk_widget_get_ancestor (GTK_WIDGET (entry), 
IDE_TYPE_WORKSPACE));
+          IdeContext *context = ide_workspace_get_context (workspace);
+
+          ide_context_warning (context, "%s", error->message);
+        }
+
       return;
     }
 
@@ -78,13 +90,15 @@ search_entry_search_cb (GObject      *object,
 
 
 static void
-search_entry_changed (DzlSuggestionEntry *entry)
+search_entry_changed (DzlSuggestionEntry *entry,
+                      IdeSearchButton    *self)
 {
   IdeSearchEngine *engine;
   IdeWorkbench *workbench;
   const gchar *typed_text;
 
   g_assert (DZL_IS_SUGGESTION_ENTRY (entry));
+  g_assert (IDE_IS_SEARCH_BUTTON (self));
 
   workbench = ide_widget_get_workbench (GTK_WIDGET (entry));
   engine = ide_workbench_get_search_engine (workbench);
@@ -93,12 +107,21 @@ search_entry_changed (DzlSuggestionEntry *entry)
   if (dzl_str_empty0 (typed_text))
     dzl_suggestion_entry_set_model (entry, NULL);
   else
-    ide_search_engine_search_async (engine,
-                                    typed_text,
-                                    DEFAULT_SEARCH_MAX,
-                                    NULL,
-                                    search_entry_search_cb,
-                                    g_object_ref (entry));
+    {
+      if (ide_search_engine_get_busy (engine))
+        g_cancellable_cancel (self->cancellable);
+
+      // Never reuse a cancellable
+      g_clear_object (&self->cancellable);
+      self->cancellable = g_cancellable_new ();
+
+      ide_search_engine_search_async (engine,
+                                      typed_text,
+                                      DEFAULT_SEARCH_MAX,
+                                      self->cancellable,
+                                      search_entry_search_cb,
+                                      g_object_ref (entry));
+    }
 }
 
 static void
@@ -196,9 +219,24 @@ search_entry_focus_in (GtkEntry      *entry,
   return GDK_EVENT_PROPAGATE;
 }
 
+static void
+ide_search_button_finalize (GObject *object)
+{
+  IdeSearchButton *self = (IdeSearchButton *)object;
+
+  g_assert (IDE_IS_SEARCH_BUTTON (self));
+
+  g_clear_object (&self->cancellable);
+
+  G_OBJECT_CLASS (ide_search_button_parent_class)->finalize (object);
+}
+
 static void
 ide_search_button_class_init (IdeSearchButtonClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = ide_search_button_finalize;
 }
 
 static void
@@ -221,7 +259,7 @@ ide_search_button_init (IdeSearchButton *self)
                                   G_ACTION_GROUP (group));
 
   dzl_gtk_widget_add_style_class (GTK_WIDGET (entry), "global-search");
-  g_signal_connect (entry, "changed", G_CALLBACK (search_entry_changed), NULL);
+  g_signal_connect (entry, "changed", G_CALLBACK (search_entry_changed), self);
   g_signal_connect (entry, "focus-in-event", G_CALLBACK (search_entry_focus_in), NULL);
   g_signal_connect (entry, "suggestion-activated", G_CALLBACK (suggestion_activated), NULL);
   dzl_suggestion_entry_set_position_func (entry, search_popover_position_func, NULL, NULL);