Locking global history_mutex

While being in darkroom we might want to lock the global history mutex for `dt_styles_apply_to_image()`.

Also _lib_history_button_clicked_callback() should get a global history lock as we select specific
history items that should not be changed from "elsewhere".

src/common/styles.c

@@ -1000,7 +1000,17 @@ void dt_styles_apply_to_image(const char *name,
                               const dt_imgid_t imgid)
 {
   dt_lock_image(imgid);
-  _styles_apply_to_image_ext(name, duplicate, overwrite, imgid, TRUE);
+
+  if(dt_view_get_current() == DT_VIEW_DARKROOM)
+  {
+    dt_print(DT_DEBUG_PIPE, "locking global history mutex");
+    dt_pthread_mutex_lock(&darktable.develop->history_mutex);
+    _styles_apply_to_image_ext(name, duplicate, overwrite, imgid, TRUE);
+    dt_pthread_mutex_unlock(&darktable.develop->history_mutex);
+  }
+  else
+    _styles_apply_to_image_ext(name, duplicate, overwrite, imgid, TRUE);
+
   dt_unlock_image(imgid);
 }
 

src/libs/history.c

@@ -1240,19 +1240,23 @@ static gboolean _lib_history_button_clicked_callback(GtkWidget *widget,
   // shift-click just show the corresponding module in modulegroups
   if(dt_modifier_is(e->state, GDK_SHIFT_MASK))
   {
+    dt_pthread_mutex_lock(&darktable.develop->history_mutex);
     const int num = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(widget), "history-number"));
     dt_dev_history_item_t *hist = g_list_nth_data(darktable.develop->history, num - 1);
     if(hist)
     {
       dt_dev_modulegroups_switch(darktable.develop, hist->module);
       dt_iop_gui_set_expanded(hist->module, TRUE, TRUE);
     }
+    dt_pthread_mutex_unlock(&darktable.develop->history_mutex);
     return TRUE;
   }
 
   dt_lib_history_t *d = self->data;
   reset = TRUE;
 
+  dt_pthread_mutex_lock(&darktable.develop->history_mutex);
+
   /* deactivate all toggle buttons */
   GList *children = gtk_container_get_children(GTK_CONTAINER(d->history_box));
   for(GList *l = children; l != NULL; l = g_list_next(l))
@@ -1265,8 +1269,11 @@ static gboolean _lib_history_button_clicked_callback(GtkWidget *widget,
   g_list_free(children);
 
   reset = FALSE;
-  if(darktable.gui->reset) return FALSE;
-
+  if(darktable.gui->reset)
+  {
+    dt_pthread_mutex_unlock(&darktable.develop->history_mutex);
+    return FALSE;
+  }
   dt_dev_undo_start_record(darktable.develop);
 
   /* revert to given history item. */
@@ -1288,6 +1295,7 @@ static gboolean _lib_history_button_clicked_callback(GtkWidget *widget,
   dt_dev_undo_end_record(darktable.develop);
 
   dt_iop_connect_accels_all();
+  dt_pthread_mutex_unlock(&darktable.develop->history_mutex);
   dt_dev_modulegroups_set(darktable.develop, dt_dev_modulegroups_get(darktable.develop));
   return FALSE;
 }