[dia] [autosave] non blocking auto save (disabled)

[Hans Breuer <hans src gnome org>]

commit 7329d4ed1cccae1753d794dd76c6df29a7a079de
Author: Hans Breuer <hans breuer org>
Date:   Sun Mar 6 14:30:47 2011 +0100

    [autosave] non blocking auto save (disabled)
    
    With embedded images the saving of diagram files finally got slow
    enough to make the blocking of the GUI annoying. Now only the data
    to be auto-saved is copied in the GUI thread. The in memory XML
    creation (especially CPU sensitive for embedded images) and the
    final diagram saving (might be slow with big files or significant
    I/O latency) are done in a thread.
    
    The code is currently disabled, because the error conditions
    (message_* use) are not thread safe. It works flawlessly when
    no error during save occurs.

 app/load_save.c |   54 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 53 insertions(+), 1 deletions(-)
---
diff --git a/app/load_save.c b/app/load_save.c
index a2fe830..121e9af 100644
--- a/app/load_save.c
+++ b/app/load_save.c
@@ -1140,8 +1140,39 @@ diagram_cleanup_autosave(Diagram *dia)
   dia->autosaved = FALSE;
 }
 
+typedef struct {
+  DiagramData *clone;
+  gchar       *filename;
+} AutoSaveInfo;
+/*!
+ * Efficient and easy to implement autosave in a thread:
+ *  - make a copy (cow?) of the whole diagram, pixbufs would not be copied but only referenced
+ *  - pass it to a saving thread as data and release it afterwards
+ *  - should show some progress, or at least not start another autosave before the previous one finished
+ *  - still must check thread safety of every function called by diagram_data_raw_save()
+ *    - e.g. all (message_*) to vanish (or make it use thread local storage?)
+ *    - no use of static data (no write access)
+ *    - ...
+ *  - the editing could continue after the synchronuous copying, which should be vastly faster
+ *    than the in memory XML creation (diagram_data_write_doc) and the writing to a possibly
+ *    slow storage (xmlDiaSaveFile)
+ */
+static gpointer
+_autosave_in_thread (gpointer data)
+{
+  AutoSaveInfo *asi = (AutoSaveInfo *)asi;
+
+  diagram_data_raw_save(asi->clone, asi->filename);
+  g_object_unref (asi->clone);
+  g_free (asi->filename);
+  g_free (asi);
+
+  return NULL;
+}
+
 /** Absolutely autosave a diagram.
- * Called after a periodic check at the first idleness.
+ * Called (in the GUI thread) after a periodic check at the first idleness.
+ *
  */
 void
 diagram_autosave(Diagram *dia)
@@ -1161,8 +1192,29 @@ diagram_autosave(Diagram *dia)
       if (dia->autosavefilename != NULL) 
 	g_free(dia->autosavefilename);
       dia->autosavefilename = save_filename;
+#ifdef AUTOSAVE_IN_THREAD /* G_THREADS_ENABLED */
+      if (g_thread_supported ()) {
+        AutoSaveInfo *asi = g_new (AutoSaveInfo, 1);
+        GError *error = NULL;
+
+	asi->clone = diagram_data_clone (dia->data);
+	asi->filename = g_strdup (save_filename);
+
+        if (!g_thread_create (_autosave_in_thread, asi, FALSE, &error)) {
+	  message_error (error->message);
+	  g_error_free (error);
+	}
+	/* FIXME: need better synchronization */
+        dia->autosaved = TRUE;
+      } else {
+	/* no extra threads supporte, stay in this one */
+        diagram_data_raw_save(dia->data, save_filename);
+        dia->autosaved = TRUE;
+      }
+#else
       diagram_data_raw_save(dia->data, save_filename);
       dia->autosaved = TRUE;
+#endif
       return;
     }
     diagrams = g_list_next(diagrams);