search: Rework threading

Search uses GcalTimeline, an object that is meant to be single
threaded, in multple threads. That mostly worked okay because
GcalTimeline mostly relies on GcalCalendarMonitor, which is
heavily threaded. But, sometimes it failed.

Rework that to be single-threaded, and asynchronous.

Closes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/981
Closes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/987
Closes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/988

3 files changed, 100 insertions, 84 deletions

diff --git a/src/search/gcal-search-engine.c b/src/search/gcal-search-engine.c
index 253daff8..47179ae6 100644
--- a/src/search/gcal-search-engine.c
+++ b/src/search/gcal-search-engine.c
@@ -22,20 +22,12 @@
 
 #include "gcal-context.h"
 #include "gcal-date-time-utils.h"
+#include "gcal-debug.h"
 #include "gcal-search-engine.h"
 #include "gcal-search-model.h"
 #include "gcal-timeline.h"
 #include "gcal-timeline-subscriber.h"
 
-typedef struct
-{
-  GcalSearchEngine   *engine;
-  gchar              *query;
-  gint                max_results;
-  GDateTime          *range_start;
-  GDateTime          *range_end;
-} SearchData;
-
 struct _GcalSearchEngine
 {
   GObject             parent;
@@ -58,59 +50,10 @@ static GParamSpec *properties [N_PROPS];
 
 
 /*
- * Auxiliary methods
- */
-
-static void
-search_data_free (gpointer data)
-{
-  SearchData *search_data = data;
-
-  if (!data)
-    return;
-
-  gcal_clear_date_time (&search_data->range_start);
-  gcal_clear_date_time (&search_data->range_end);
-  g_clear_pointer (&search_data->query, g_free);
-  g_clear_object (&search_data->engine);
-  g_slice_free (SearchData, data);
-}
-
-
-/*
  * Callbacks
  */
 
 static void
-search_func (GTask        *task,
-             gpointer      source_object,
-             gpointer      task_data,
-             GCancellable *cancellable)
-{
-  g_autoptr (GcalSearchModel) model = NULL;
-  GcalSearchEngine *self;
-  SearchData *data;
-
-  self = GCAL_SEARCH_ENGINE (source_object);
-  data = (SearchData*) task_data;
-
-  model = gcal_search_model_new (cancellable,
-                                 data->max_results,
-                                 data->range_start,
-                                 data->range_end);
-
-  gcal_timeline_set_filter (self->timeline, data->query);
-  gcal_timeline_add_subscriber (self->timeline, GCAL_TIMELINE_SUBSCRIBER (model));
-
-  gcal_search_model_wait_for_hits (model, cancellable);
-
-  if (g_cancellable_is_cancelled (cancellable))
-    g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_CANCELLED, "Cancelled");
-  else
-    g_task_return_pointer (task, g_steal_pointer (&model), g_object_unref);
-}
-
-static void
 on_manager_calendar_added_cb (GcalManager      *manager,
                               GcalCalendar     *calendar,
                               GcalSearchEngine *self)
@@ -130,6 +73,31 @@ on_manager_calendar_removed_cb (GcalManager      *manager,
   gcal_timeline_remove_calendar (self->timeline, calendar);
 }
 
+static void
+search_model_hits_cb (GObject      *source,
+                      GAsyncResult *result,
+                      gpointer      data)
+{
+  g_autoptr (GError) error = NULL;
+  g_autoptr (GTask) task = data;
+  GcalSearchModel *search_model;
+
+  GCAL_ENTRY;
+
+  search_model = GCAL_SEARCH_MODEL (source);
+  gcal_search_model_wait_for_hits_finish (search_model, result, &error);
+
+  if (error)
+    {
+      g_task_return_error (task, g_steal_pointer (&error));
+      GCAL_RETURN ();
+    }
+
+  g_task_return_pointer (task, g_object_ref (search_model), NULL);
+
+  GCAL_EXIT;
+}
+
 
 /*
  * GObject overrides
@@ -246,9 +214,11 @@ gcal_search_engine_search (GcalSearchEngine    *self,
                            GAsyncReadyCallback  callback,
                            gpointer             user_data)
 {
+  g_autoptr (GcalSearchModel) model = NULL;
+  g_autoptr (GDateTime) range_start = NULL;
+  g_autoptr (GDateTime) range_end = NULL;
   g_autoptr (GDateTime) now = NULL;
   g_autoptr (GTask) task = NULL;
-  SearchData *data = NULL;
   GTimeZone *timezone;
 
   g_return_if_fail (GCAL_IS_SEARCH_ENGINE (self));
@@ -256,20 +226,18 @@ gcal_search_engine_search (GcalSearchEngine    *self,
 
   timezone = gcal_context_get_timezone (self->context);
   now = g_date_time_new_now (timezone);
+  range_start = g_date_time_add_weeks (now, -1);
+  range_end = g_date_time_add_weeks (now, 3);
+  model = gcal_search_model_new (cancellable, max_results, range_start, range_end);
 
-  data = g_slice_new0 (SearchData);
-  data->engine = g_object_ref (self);
-  data->query = g_strdup (search_query);
-  data->max_results = max_results;
-  data->range_start = g_date_time_add_weeks (now, -1);
-  data->range_end = g_date_time_add_weeks (now, 3);
+  gcal_timeline_set_filter (self->timeline, search_query);
+  gcal_timeline_add_subscriber (self->timeline, GCAL_TIMELINE_SUBSCRIBER (model));
 
   task = g_task_new (self, cancellable, callback, user_data);
   g_task_set_source_tag (task, gcal_search_engine_search);
   g_task_set_priority (task, G_PRIORITY_LOW);
-  g_task_set_task_data (task, data, (GDestroyNotify) search_data_free);
 
-  g_task_run_in_thread (task, search_func);
+  gcal_search_model_wait_for_hits (model, cancellable, search_model_hits_cb, g_object_ref (task));
 }
 
 GListModel*
diff --git a/src/search/gcal-search-model.c b/src/search/gcal-search-model.c
index 892878b3..08cc0370 100644
--- a/src/search/gcal-search-model.c
+++ b/src/search/gcal-search-model.c
@@ -42,6 +42,9 @@ struct _GcalSearchModel
   GDateTime          *range_end;
 
   GListModel         *model;
+
+  GTimer             *timer;
+  guint               idle_id;
 };
 
 static void          gcal_timeline_subscriber_interface_init     (GcalTimelineSubscriberInterface *iface);
@@ -58,6 +61,33 @@ G_DEFINE_TYPE_WITH_CODE (GcalSearchModel, gcal_search_model, G_TYPE_OBJECT,
  * Callbacks
  */
 
+static gboolean
+check_for_search_hits_cb (gpointer user_data)
+{
+  GcalSearchModel *self;
+  GTask *task;
+
+  task = G_TASK (user_data);
+  self = GCAL_SEARCH_MODEL (g_task_get_source_object (task));
+
+  if (g_task_return_error_if_cancelled (task))
+    goto stop_idle;
+
+  if (g_timer_elapsed (self->timer, NULL) >= WAIT_FOR_RESULTS_MS ||
+      g_list_model_get_n_items (self->model) >= MIN_RESULTS)
+    {
+      g_task_return_boolean (task, TRUE);
+      goto stop_idle;
+    }
+
+  return G_SOURCE_CONTINUE;
+
+stop_idle:
+  g_clear_pointer (&self->timer, g_timer_destroy);
+  self->idle_id = 0;
+  return G_SOURCE_REMOVE;
+}
+
 static void
 on_model_items_changed_cb (GListModel      *model,
                            guint            position,
@@ -208,6 +238,9 @@ gcal_search_model_finalize (GObject *object)
 {
   GcalSearchModel *self = (GcalSearchModel *)object;
 
+  g_assert (self->timer == NULL);
+  g_assert (self->idle_id == 0);
+
   g_cancellable_cancel (self->cancellable);
 
   gcal_clear_date_time (&self->range_start);
@@ -251,29 +284,38 @@ gcal_search_model_new (GCancellable *cancellable,
 }
 
 void
-gcal_search_model_wait_for_hits (GcalSearchModel *self,
-                                 GCancellable    *cancellable)
+gcal_search_model_wait_for_hits (GcalSearchModel     *self,
+                                 GCancellable        *cancellable,
+                                 GAsyncReadyCallback  callback,
+                                 gpointer             user_data)
 {
-  g_autoptr (GMainContext) thread_context = NULL;
-  g_autoptr (GTimer) timer = NULL;
+  g_autoptr (GTask) task = NULL;
 
   GCAL_ENTRY;
 
-  g_return_if_fail (GCAL_IS_SEARCH_MODEL (self));
+  g_assert (self->timer == NULL);
+  g_assert (self->idle_id == 0);
 
-  thread_context = g_main_context_ref_thread_default ();
-  timer = g_timer_new ();
+  task = g_task_new (self, cancellable, callback, user_data);
+  g_task_set_source_tag (task, gcal_search_model_wait_for_hits);
+  g_task_set_priority (task, G_PRIORITY_LOW);
 
-  g_timer_start (timer);
+  self->timer = g_timer_new ();
+  self->idle_id = g_idle_add_full (G_PRIORITY_LOW,
+                                   check_for_search_hits_cb,
+                                   g_object_ref (task),
+                                   g_object_unref);
 
-  while (g_list_model_get_n_items (self->model) < MIN_RESULTS &&
-         g_timer_elapsed (timer, NULL) < WAIT_FOR_RESULTS_MS)
-    {
-      if (g_cancellable_is_cancelled (cancellable))
-        break;
+  GCAL_EXIT;
+}
 
-      g_main_context_iteration (thread_context, FALSE);
-    }
+gboolean
+gcal_search_model_wait_for_hits_finish (GcalSearchModel  *self,
+                                        GAsyncResult     *result,
+                                        GError          **error)
+{
+  g_return_val_if_fail (GCAL_IS_SEARCH_MODEL (self), FALSE);
+  g_return_val_if_fail (g_task_is_valid (result, self), FALSE);
 
-  GCAL_EXIT;
+  return g_task_propagate_boolean (G_TASK (result), error);
 }
diff --git a/src/search/gcal-search-model.h b/src/search/gcal-search-model.h
index 97775834..8f040a00 100644
--- a/src/search/gcal-search-model.h
+++ b/src/search/gcal-search-model.h
@@ -33,6 +33,12 @@ GcalSearchModel*     gcal_search_model_new                       (GCancellable
                                                                   GDateTime          *range_end);
 
 void                 gcal_search_model_wait_for_hits             (GcalSearchModel    *self,
-                                                                  GCancellable       *cancellable);
+                                                                  GCancellable       *cancellable,
+                                                                  GAsyncReadyCallback callback,
+                                                                  gpointer            user_data);
+
+gboolean             gcal_search_model_wait_for_hits_finish      (GcalSearchModel    *self,
+                                                                  GAsyncResult       *result,
+                                                                  GError            **error);
 
 G_END_DECLS