[gtk/wip/otte/sortlistmodel: 12/38] REMOVE: Copy current sort model to Tim2SortModel

[Benjamin Otte <otte src gnome org>]

commit 51e64eee0112095f839ab796b585085393b33d48
Author: Benjamin Otte <otte redhat com>
Date:   Sun Jul 12 17:23:45 2020 +0200

    REMOVE: Copy current sort model to Tim2SortModel
    
    This is the state of the model with incremental sorting support, before
    doing some surgery that might slow down operations.

 gtk/gtk.h              |   1 +
 gtk/gtktim2sortmodel.c | 789 +++++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtktim2sortmodel.h |  63 ++++
 gtk/meson.build        |   2 +
 4 files changed, 855 insertions(+)
---
diff --git a/gtk/gtk.h b/gtk/gtk.h
index 9d37dcc632..6cd8345cc5 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -260,6 +260,7 @@
 #include <gtk/gtktexttagtable.h>
 #include <gtk/gtktextview.h>
 #include <gtk/gtktim1sortmodel.h>
+#include <gtk/gtktim2sortmodel.h>
 #include <gtk/gtktogglebutton.h>
 #include <gtk/gtktooltip.h>
 #include <gtk/gtktestutils.h>
diff --git a/gtk/gtktim2sortmodel.c b/gtk/gtktim2sortmodel.c
new file mode 100644
index 0000000000..a4eeceb256
--- /dev/null
+++ b/gtk/gtktim2sortmodel.c
@@ -0,0 +1,789 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * 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 2.1 of the License, 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte gnome org>
+ */
+
+#include "config.h"
+
+#include "gtktim2sortmodel.h"
+
+#include "gtkintl.h"
+#include "gtkprivate.h"
+#include "gtktimsortprivate.h"
+
+typedef struct _SortItem SortItem;
+struct _SortItem
+{
+  GObject *item;
+  guint position;
+};
+
+static void
+sort_item_clear (gpointer data)
+{
+  SortItem *si = data;
+
+  g_clear_object (&si->item);
+}
+
+#define GDK_ARRAY_ELEMENT_TYPE SortItem
+#define GDK_ARRAY_TYPE_NAME SortArray
+#define GDK_ARRAY_NAME sort_array
+#define GDK_ARRAY_FREE_FUNC sort_item_clear
+#define GDK_ARRAY_BY_VALUE 1
+#include "gdk/gdkarrayimpl.c"
+
+/**
+ * SECTION:gtksor4listmodel
+ * @title: GtkTim2SortModel
+ * @short_description: A list model that sorts its items
+ * @see_also: #GListModel, #GtkSorter
+ *
+ * #GtkTim2SortModel is a list model that takes a list model and
+ * sorts its elements according to a #GtkSorter.
+ *
+ * #GtkTim2SortModel is a generic model and because of that it
+ * cannot take advantage of any external knowledge when sorting.
+ * If you run into performance issues with #GtkTim2SortModel, it
+ * is strongly recommended that you write your own sorting list
+ * model.
+ */
+
+enum {
+  PROP_0,
+  PROP_INCREMENTAL,
+  PROP_MODEL,
+  PROP_SORTER,
+  NUM_PROPERTIES
+};
+
+struct _GtkTim2SortModel
+{
+  GObject parent_instance;
+
+  GListModel *model;
+  GtkSorter *sorter;
+  gboolean incremental;
+
+  GtkTimSort sort; /* ongoing sort operation */
+  guint sort_cb; /* 0 or current ongoing sort callback */
+  SortArray items; /* empty if known unsorted */
+};
+
+struct _GtkTim2SortModelClass
+{
+  GObjectClass parent_class;
+};
+
+static GParamSpec *properties[NUM_PROPERTIES] = { NULL, };
+
+static GType
+gtk_tim2_sort_model_get_item_type (GListModel *list)
+{
+  return G_TYPE_OBJECT;
+}
+
+static guint
+gtk_tim2_sort_model_get_n_items (GListModel *list)
+{
+  GtkTim2SortModel *self = GTK_TIM2_SORT_MODEL (list);
+
+  if (self->model == NULL)
+    return 0;
+
+  return g_list_model_get_n_items (self->model);
+}
+
+static gpointer
+gtk_tim2_sort_model_get_item (GListModel *list,
+                              guint       position)
+{
+  GtkTim2SortModel *self = GTK_TIM2_SORT_MODEL (list);
+
+  if (self->model == NULL)
+    return NULL;
+
+  if (sort_array_is_empty (&self->items))
+    return g_list_model_get_item (self->model, position);
+
+  if (position >= sort_array_get_size (&self->items))
+    return NULL;
+
+  return g_object_ref (sort_array_get (&self->items, position)->item);
+}
+
+static void
+gtk_tim2_sort_model_model_init (GListModelInterface *iface)
+{
+  iface->get_item_type = gtk_tim2_sort_model_get_item_type;
+  iface->get_n_items = gtk_tim2_sort_model_get_n_items;
+  iface->get_item = gtk_tim2_sort_model_get_item;
+}
+
+G_DEFINE_TYPE_WITH_CODE (GtkTim2SortModel, gtk_tim2_sort_model, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, gtk_tim2_sort_model_model_init))
+
+static gboolean
+gtk_tim2_sort_model_is_sorting (GtkTim2SortModel *self)
+{
+  return self->sort_cb != 0;
+}
+
+static void
+gtk_tim2_sort_model_stop_sorting (GtkTim2SortModel *self,
+                                  gsize            *runs)
+{
+  if (self->sort_cb == 0)
+    {
+      if (runs)
+        {
+          runs[0] = sort_array_get_size (&self->items);
+          runs[1] = 0;
+        }
+      return;
+    }
+
+  if (runs)
+    gtk_tim_sort_get_runs (&self->sort, runs);
+  gtk_tim_sort_finish (&self->sort);
+  g_clear_handle_id (&self->sort_cb, g_source_remove);
+}
+
+static gboolean
+gtk_tim2_sort_model_sort_step (GtkTim2SortModel *self,
+                               gboolean          finish,
+                               guint            *out_position,
+                               guint            *out_n_items)
+{
+  gint64 end_time = g_get_monotonic_time ();
+  gboolean result = FALSE;
+  GtkTimSortRun change;
+  SortItem *start_change, *end_change;
+
+  /* 1 millisecond */
+  end_time += 1000;
+  end_change = sort_array_get_data (&self->items);
+  start_change = end_change + sort_array_get_size (&self->items);
+
+  while (gtk_tim_sort_step (&self->sort, &change))
+    {
+      result = TRUE;
+      if (change.len)
+        {
+          start_change = MIN (start_change, (SortItem *) change.base);
+          end_change = MAX (end_change, ((SortItem *) change.base) + change.len);
+        }
+     
+      if (g_get_monotonic_time () >= end_time && !finish)
+        break;
+    }
+
+  if (start_change < end_change)
+    {
+      *out_position = start_change - sort_array_get_data (&self->items);
+      *out_n_items = end_change - start_change;
+    }
+  else
+    {
+      *out_position = 0;
+      *out_n_items = 0;
+    }
+
+  return result;
+}
+
+static gboolean
+gtk_tim2_sort_model_sort_cb (gpointer data)
+{
+  GtkTim2SortModel *self = data;
+  guint pos, n_items;
+
+  if (gtk_tim2_sort_model_sort_step (self, FALSE, &pos, &n_items))
+    {
+      if (n_items)
+        g_list_model_items_changed (G_LIST_MODEL (self), pos, n_items, n_items);
+      return G_SOURCE_CONTINUE;
+    }
+
+  gtk_tim2_sort_model_stop_sorting (self, NULL);
+  return G_SOURCE_REMOVE;
+}
+
+static int
+sort_func (gconstpointer a,
+           gconstpointer b,
+           gpointer      data)
+{
+  SortItem *sa = (SortItem *) a;
+  SortItem *sb = (SortItem *) b;
+
+  return gtk_sorter_compare (data, sa->item, sb->item);
+}
+
+static gboolean
+gtk_tim2_sort_model_start_sorting (GtkTim2SortModel *self,
+                                   gsize            *runs)
+{
+  g_assert (self->sort_cb == 0);
+
+  gtk_tim_sort_init (&self->sort,
+                     sort_array_get_data (&self->items),
+                     sort_array_get_size (&self->items),
+                     sizeof (SortItem),
+                     sort_func,
+                     self->sorter);
+  if (runs)
+    gtk_tim_sort_set_runs (&self->sort, runs);
+  if (self->incremental)
+    gtk_tim_sort_set_max_merge_size (&self->sort, 1024);
+
+  if (!self->incremental)
+    return FALSE;
+
+  self->sort_cb = g_idle_add (gtk_tim2_sort_model_sort_cb, self);
+  return TRUE;
+}
+
+static void
+gtk_tim2_sort_model_finish_sorting (GtkTim2SortModel *self,
+                                    guint            *pos,
+                                    guint            *n_items)
+{
+  gtk_tim_sort_set_max_merge_size (&self->sort, 0);
+
+  gtk_tim2_sort_model_sort_step (self, TRUE, pos, n_items);
+  gtk_tim_sort_finish (&self->sort);
+
+  gtk_tim2_sort_model_stop_sorting (self, NULL);
+}
+
+static void
+gtk_tim2_sort_model_clear_items (GtkTim2SortModel *self,
+                                 guint            *pos,
+                                 guint            *n_items)
+{
+  gtk_tim2_sort_model_stop_sorting (self, NULL);
+
+  if (pos || n_items)
+    {
+      guint start, end;
+
+      for (start = 0; start < sort_array_get_size (&self->items); start++)
+        {
+          if (sort_array_index (&self->items, start)->position != start)
+            break;
+        }
+      for (end = sort_array_get_size (&self->items); end > start; end--)
+        {
+          if (sort_array_index (&self->items, end - 1)->position != end - 1)
+            break;
+        }
+
+      *n_items = end - start;
+      if (*n_items == 0)
+        *pos = 0;
+      else
+        *pos = start;
+    }
+
+  sort_array_clear (&self->items);
+} 
+
+static gboolean
+gtk_tim2_sort_model_should_sort (GtkTim2SortModel *self)
+{
+  return self->sorter != NULL &&
+         self->model != NULL &&
+         gtk_sorter_get_order (self->sorter) != GTK_SORTER_ORDER_NONE;
+}
+
+static void
+gtk_tim2_sort_model_create_items (GtkTim2SortModel *self)
+{
+  guint i, n_items;
+
+  if (!gtk_tim2_sort_model_should_sort (self))
+    return;
+
+  n_items = g_list_model_get_n_items (self->model);
+  sort_array_reserve (&self->items, n_items);
+  for (i = 0; i < n_items; i++)
+    {
+      sort_array_append (&self->items, &(SortItem) { g_list_model_get_item (self->model, i), i });
+    }
+}
+
+static void
+gtk_tim2_sort_model_update_items (GtkTim2SortModel *self,
+                                  gsize             runs[GTK_TIM_SORT_MAX_PENDING + 1],
+                                  guint             position,
+                                  guint             removed,
+                                  guint             added,
+                                  guint            *unmodified_start,
+                                  guint            *unmodified_end)
+{
+  guint i, n_items, valid;
+  guint start, end;
+
+  n_items = sort_array_get_size (&self->items);
+  start = n_items;
+  end = n_items;
+  
+  valid = 0;
+  for (i = 0; i < n_items; i++)
+    {
+      SortItem *si = sort_array_index (&self->items, i);
+
+      if (si->position >= position + removed)
+        si->position = si->position - removed + added;
+      else if (si->position >= position)
+        { 
+          start = MIN (start, valid);
+          end = n_items - i - 1;
+          sort_item_clear (si);
+          continue;
+        }
+      if (valid < i)
+        *sort_array_index (&self->items, valid) = *sort_array_index (&self->items, i);
+      valid++;
+    }
+
+  /* FIXME */
+  runs[0] = 0;
+
+  g_assert (valid == n_items - removed);
+  memset (sort_array_index (&self->items, valid), 0, sizeof (SortItem) * removed); 
+  sort_array_set_size (&self->items, valid);
+
+  *unmodified_start = start;
+  *unmodified_end = end;
+}
+
+static void
+gtk_tim2_sort_model_items_changed_cb (GListModel       *model,
+                                      guint             position,
+                                      guint             removed,
+                                      guint             added,
+                                      GtkTim2SortModel *self)
+{
+  gsize runs[GTK_TIM_SORT_MAX_PENDING + 1];
+  guint i, n_items, start, end;
+  gboolean was_sorting;
+
+  if (removed == 0 && added == 0)
+    return;
+
+  if (!gtk_tim2_sort_model_should_sort (self))
+    {
+      g_list_model_items_changed (G_LIST_MODEL (self), position, removed, added);
+      return;
+    }
+
+  was_sorting = gtk_tim2_sort_model_is_sorting (self);
+  gtk_tim2_sort_model_stop_sorting (self, runs);
+
+  gtk_tim2_sort_model_update_items (self, runs, position, removed, added, &start, &end);
+
+  if (added > 0)
+    {
+      gboolean success;
+
+      sort_array_reserve (&self->items, sort_array_get_size (&self->items) + added);
+      for (i = position; i < position + added; i++)
+        {
+          sort_array_append (&self->items, &(SortItem) { g_list_model_get_item (self->model, i), i });
+        }
+
+      end = 0;
+      success = gtk_tim2_sort_model_start_sorting (self, runs);
+      if (!success)
+        {
+          guint pos, n;
+          gtk_tim2_sort_model_finish_sorting (self, &pos, &n);
+          start = MIN (start, pos);
+          end = MIN (end, sort_array_get_size (&self->items) - pos - n);
+        }
+    }
+  else
+    {
+      if (was_sorting)
+        gtk_tim2_sort_model_start_sorting (self, runs);
+    }
+
+  n_items = sort_array_get_size (&self->items) - start - end;
+  g_list_model_items_changed (G_LIST_MODEL (self), start, n_items - added + removed, n_items);
+}
+
+static void
+gtk_tim2_sort_model_set_property (GObject      *object,
+                                  guint         prop_id,
+                                  const GValue *value,
+                                  GParamSpec   *pspec)
+{
+  GtkTim2SortModel *self = GTK_TIM2_SORT_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_INCREMENTAL:
+      gtk_tim2_sort_model_set_incremental (self, g_value_get_boolean (value));
+      break;
+
+    case PROP_MODEL:
+      gtk_tim2_sort_model_set_model (self, g_value_get_object (value));
+      break;
+
+    case PROP_SORTER:
+      gtk_tim2_sort_model_set_sorter (self, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void 
+gtk_tim2_sort_model_get_property (GObject     *object,
+                                  guint        prop_id,
+                                  GValue      *value,
+                                  GParamSpec  *pspec)
+{
+  GtkTim2SortModel *self = GTK_TIM2_SORT_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_INCREMENTAL:
+      g_value_set_boolean (value, self->incremental);
+      break;
+
+    case PROP_MODEL:
+      g_value_set_object (value, self->model);
+      break;
+
+    case PROP_SORTER:
+      g_value_set_object (value, self->sorter);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_tim2_sort_model_sorter_changed_cb (GtkSorter        *sorter,
+                                       int               change,
+                                       GtkTim2SortModel *self)
+{
+  guint pos, n_items;
+
+  if (gtk_sorter_get_order (sorter) == GTK_SORTER_ORDER_NONE)
+    gtk_tim2_sort_model_clear_items (self, &pos, &n_items);
+  else
+    {
+      if (sort_array_is_empty (&self->items))
+        gtk_tim2_sort_model_create_items (self);
+
+      gtk_tim2_sort_model_stop_sorting (self, NULL);
+
+      if (gtk_tim2_sort_model_start_sorting (self, NULL))
+        pos = n_items = 0;
+      else
+        gtk_tim2_sort_model_finish_sorting (self, &pos, &n_items);
+    }
+
+  if (n_items > 0)
+    g_list_model_items_changed (G_LIST_MODEL (self), pos, n_items, n_items);
+}
+
+static void
+gtk_tim2_sort_model_clear_model (GtkTim2SortModel *self)
+{
+  if (self->model == NULL)
+    return;
+
+  g_signal_handlers_disconnect_by_func (self->model, gtk_tim2_sort_model_items_changed_cb, self);
+  g_clear_object (&self->model);
+  gtk_tim2_sort_model_clear_items (self, NULL, NULL);
+}
+
+static void
+gtk_tim2_sort_model_clear_sorter (GtkTim2SortModel *self)
+{
+  if (self->sorter == NULL)
+    return;
+
+  g_signal_handlers_disconnect_by_func (self->sorter, gtk_tim2_sort_model_sorter_changed_cb, self);
+  g_clear_object (&self->sorter);
+}
+
+static void
+gtk_tim2_sort_model_dispose (GObject *object)
+{
+  GtkTim2SortModel *self = GTK_TIM2_SORT_MODEL (object);
+
+  gtk_tim2_sort_model_clear_model (self);
+  gtk_tim2_sort_model_clear_sorter (self);
+
+  G_OBJECT_CLASS (gtk_tim2_sort_model_parent_class)->dispose (object);
+};
+
+static void
+gtk_tim2_sort_model_class_init (GtkTim2SortModelClass *class)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (class);
+
+  gobject_class->set_property = gtk_tim2_sort_model_set_property;
+  gobject_class->get_property = gtk_tim2_sort_model_get_property;
+  gobject_class->dispose = gtk_tim2_sort_model_dispose;
+
+  /**
+   * GtkTim2SortModel:incremental:
+   *
+   * If the model should sort items incrementally
+   */
+  properties[PROP_INCREMENTAL] =
+      g_param_spec_boolean ("incremental",
+                            P_("Incremental"),
+                            P_("Sort items incrementally"),
+                            FALSE,
+                            GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkTim2SortModel:model:
+   *
+   * The model being sorted
+   */
+  properties[PROP_MODEL] =
+      g_param_spec_object ("model",
+                           P_("Model"),
+                           P_("The model being sorted"),
+                           G_TYPE_LIST_MODEL,
+                           GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkTim2SortModel:sorter:
+   *
+   * The sorter for this model
+   */
+  properties[PROP_SORTER] =
+      g_param_spec_object ("sorter",
+                            P_("Sorter"),
+                            P_("The sorter for this model"),
+                            GTK_TYPE_SORTER,
+                            GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  g_object_class_install_properties (gobject_class, NUM_PROPERTIES, properties);
+}
+
+static void
+gtk_tim2_sort_model_init (GtkTim2SortModel *self)
+{
+}
+
+/**
+ * gtk_tim2_sort_model_new:
+ * @model: (allow-none): the model to sort
+ * @sorter: (allow-none): the #GtkSorter to sort @model with
+ *
+ * Creates a new sort list model that uses the @sorter to sort @model.
+ *
+ * Returns: a new #GtkTim2SortModel
+ **/
+GtkTim2SortModel *
+gtk_tim2_sort_model_new (GListModel *model,
+                         GtkSorter  *sorter)
+{
+  GtkTim2SortModel *result;
+
+  g_return_val_if_fail (model == NULL || G_IS_LIST_MODEL (model), NULL);
+  g_return_val_if_fail (sorter == NULL || GTK_IS_SORTER (sorter), NULL);
+
+  result = g_object_new (GTK_TYPE_TIM2_SORT_MODEL,
+                         "model", model,
+                         "sorter", sorter,
+                         NULL);
+
+  return result;
+}
+
+/**
+ * gtk_tim2_sort_model_set_model:
+ * @self: a #GtkTim2SortModel
+ * @model: (allow-none): The model to be sorted
+ *
+ * Sets the model to be sorted. The @model's item type must conform to
+ * the item type of @self.
+ **/
+void
+gtk_tim2_sort_model_set_model (GtkTim2SortModel *self,
+                               GListModel       *model)
+{
+  guint removed, added;
+
+  g_return_if_fail (GTK_IS_TIM2_SORT_MODEL (self));
+  g_return_if_fail (model == NULL || G_IS_LIST_MODEL (model));
+
+  if (self->model == model)
+    return;
+
+  removed = g_list_model_get_n_items (G_LIST_MODEL (self));
+  gtk_tim2_sort_model_clear_model (self);
+
+  if (model)
+    {
+      guint ignore1, ignore2;
+
+      self->model = g_object_ref (model);
+      g_signal_connect (model, "items-changed", G_CALLBACK (gtk_tim2_sort_model_items_changed_cb), self);
+      added = g_list_model_get_n_items (model);
+
+      gtk_tim2_sort_model_create_items (self);
+      if (!gtk_tim2_sort_model_start_sorting (self, NULL))
+        gtk_tim2_sort_model_finish_sorting (self, &ignore1, &ignore2);
+    }
+  else
+    added = 0;
+  
+  if (removed > 0 || added > 0)
+    g_list_model_items_changed (G_LIST_MODEL (self), 0, removed, added);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_MODEL]);
+}
+
+/**
+ * gtk_tim2_sort_model_get_model:
+ * @self: a #GtkTim2SortModel
+ *
+ * Gets the model currently sorted or %NULL if none.
+ *
+ * Returns: (nullable) (transfer none): The model that gets sorted
+ **/
+GListModel *
+gtk_tim2_sort_model_get_model (GtkTim2SortModel *self)
+{
+  g_return_val_if_fail (GTK_IS_TIM2_SORT_MODEL (self), NULL);
+
+  return self->model;
+}
+
+/**
+ * gtk_tim2_sort_model_set_sorter:
+ * @self: a #GtkTim2SortModel
+ * @sorter: (allow-none): the #GtkSorter to sort @model with
+ *
+ * Sets a new sorter on @self.
+ */
+void
+gtk_tim2_sort_model_set_sorter (GtkTim2SortModel *self,
+                                GtkSorter        *sorter)
+{
+  g_return_if_fail (GTK_IS_TIM2_SORT_MODEL (self));
+  g_return_if_fail (sorter == NULL || GTK_IS_SORTER (sorter));
+
+  gtk_tim2_sort_model_clear_sorter (self);
+
+  if (sorter)
+    {
+      self->sorter = g_object_ref (sorter);
+      g_signal_connect (sorter, "changed", G_CALLBACK (gtk_tim2_sort_model_sorter_changed_cb), self);
+      gtk_tim2_sort_model_sorter_changed_cb (sorter, GTK_SORTER_CHANGE_DIFFERENT, self);
+    }
+  else
+    {
+      guint n_items = g_list_model_get_n_items (G_LIST_MODEL (self));
+      if (n_items > 1)
+        g_list_model_items_changed (G_LIST_MODEL (self), 0, n_items, n_items);
+    }
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SORTER]);
+}
+
+/**
+ * gtk_tim2_sort_model_get_sorter:
+ * @self: a #GtkTim2SortModel
+ *
+ * Gets the sorter that is used to sort @self.
+ *
+ * Returns: (nullable) (transfer none): the sorter of #self
+ */
+GtkSorter *
+gtk_tim2_sort_model_get_sorter (GtkTim2SortModel *self)
+{
+  g_return_val_if_fail (GTK_IS_TIM2_SORT_MODEL (self), NULL);
+
+  return self->sorter;
+}
+
+/**
+ * gtk_tim2_sort_model_set_incremental:
+ * @self: a #GtkTim2SortModel
+ * @incremental: %TRUE to sort incrementally
+ *
+ * Sets the sort model to do an incremental sort.
+ *
+ * When incremental sorting is enabled, the sortlistmodel will not do
+ * a complete sort immediately, but will instead queue an idle handler that
+ * incrementally sorts the items towards their correct position. This of
+ * course means that items do not instantly appear in the right place. It
+ * also means that the total sorting time is a lot slower.
+ *
+ * When your filter blocks the UI while sorting, you might consider
+ * turning this on. Depending on your model and sorters, this may become
+ * interesting around 10,000 to 100,000 items.
+ *
+ * By default, incremental sortinging is disabled.
+ */
+void
+gtk_tim2_sort_model_set_incremental (GtkTim2SortModel *self,
+                                     gboolean          incremental)
+{
+  g_return_if_fail (GTK_IS_TIM2_SORT_MODEL (self));
+
+  if (self->incremental == incremental)
+    return;
+
+  self->incremental = incremental;
+
+  if (!incremental && gtk_tim2_sort_model_is_sorting (self))
+    {
+      guint pos, n_items;
+
+      gtk_tim2_sort_model_finish_sorting (self, &pos, &n_items);
+      if (n_items)
+        g_list_model_items_changed (G_LIST_MODEL (self), pos, n_items, n_items);
+    }
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_INCREMENTAL]);
+}
+
+/**
+ * gtk_tim2_sort_model_get_incremental:
+ * @self: a #GtkModel
+ *
+ * Returns whether incremental sorting was enabled via
+ * gtk_sort_list_model_set_incremental().
+ *
+ * Returns: %TRUE if incremental sorting is enabled
+ */
+gboolean
+gtk_tim2_sort_model_get_incremental (GtkTim2SortModel *self)
+{
+  g_return_val_if_fail (GTK_IS_TIM2_SORT_MODEL (self), FALSE);
+
+  return self->incremental;
+}
diff --git a/gtk/gtktim2sortmodel.h b/gtk/gtktim2sortmodel.h
new file mode 100644
index 0000000000..17beb2edfd
--- /dev/null
+++ b/gtk/gtktim2sortmodel.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * 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 2.1 of the License, 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte gnome org>
+ */
+
+#ifndef __GTK_TIM2_SORT_MODEL_H__
+#define __GTK_TIM2_SORT_MODEL_H__
+
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gio/gio.h>
+#include <gtk/gtkwidget.h>
+#include <gtk/gtksorter.h>
+
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_TIM2_SORT_MODEL (gtk_tim2_sort_model_get_type ())
+
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkTim2SortModel, gtk_tim2_sort_model, GTK, TIM2_SORT_MODEL, GObject)
+
+GDK_AVAILABLE_IN_ALL
+GtkTim2SortModel *      gtk_tim2_sort_model_new                 (GListModel            *model,
+                                                                 GtkSorter             *sorter);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_tim2_sort_model_set_sorter          (GtkTim2SortModel       *self,
+                                                                 GtkSorter              *sorter);
+GDK_AVAILABLE_IN_ALL
+GtkSorter *             gtk_tim2_sort_model_get_sorter          (GtkTim2SortModel       *self);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_tim2_sort_model_set_model           (GtkTim2SortModel       *self,
+                                                                 GListModel             *model);
+GDK_AVAILABLE_IN_ALL
+GListModel *            gtk_tim2_sort_model_get_model           (GtkTim2SortModel       *self);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_tim2_sort_model_set_incremental     (GtkTim2SortModel       *self,
+                                                                 gboolean                incremental);
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_tim2_sort_model_get_incremental     (GtkTim2SortModel       *self);
+
+G_END_DECLS
+
+#endif /* __GTK_TIM2_SORT_MODEL_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index df30f5ab3b..aa63a16695 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -403,6 +403,7 @@ gtk_public_sources = files([
   'gtktextutil.c',
   'gtktextview.c',
   'gtktim1sortmodel.c',
+  'gtktim2sortmodel.c',
   'gtktogglebutton.c',
   'gtktooltip.c',
   'gtktooltipwindow.c',
@@ -669,6 +670,7 @@ gtk_public_headers = files([
   'gtktexttagtable.h',
   'gtktextview.h',
   'gtktim1sortmodel.h',
+  'gtktim2sortmodel.h',
   'gtktogglebutton.h',
   'gtktooltip.h',
   'gtktreednd.h',