[mutter] x11: Avoid memory waste and work when creating selection input stream

[Marge Bot <marge-bot src gnome org>]

commit 986d3043ab5c65e9d1bf16eb0ed51d964d7ebd18
Author: Sebastian Keller <skeller gnome org>
Date:   Mon Apr 5 13:04:46 2021 +0200

    x11: Avoid memory waste and work when creating selection input stream
    
    Since every input stream now uses its own window, the X property used to
    transfer the data no longer has to be unique, so we can stop generating
    those unique names. This avoids creating a new atom for every transfer
    since those are never freed, neither on the shell nor on the server
    side. Also don't unnecessarily duplicate other strings that are
    (almost) never used and get them from the atom in the rare case when
    they are needed.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/-/issues/1328
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1812>

 src/x11/meta-x11-selection-input-stream.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)
---
diff --git a/src/x11/meta-x11-selection-input-stream.c b/src/x11/meta-x11-selection-input-stream.c
index 8a1318a89f..9747fa505e 100644
--- a/src/x11/meta-x11-selection-input-stream.c
+++ b/src/x11/meta-x11-selection-input-stream.c
@@ -40,11 +40,8 @@ struct MetaX11SelectionInputStreamPrivate
   MetaX11Display *x11_display;
   Window window;
   GAsyncQueue *chunks;
-  char *selection;
   Atom xselection;
-  char *target;
   Atom xtarget;
-  char *property;
   Atom xproperty;
   const char *type;
   Atom xtype;
@@ -291,10 +288,6 @@ meta_x11_selection_input_stream_finalize (GObject *object)
 
   g_async_queue_unref (priv->chunks);
 
-  g_free (priv->selection);
-  g_free (priv->target);
-  g_free (priv->property);
-
   XDestroyWindow (xdisplay, priv->window);
 
   G_OBJECT_CLASS (meta_x11_selection_input_stream_parent_class)->finalize (object);
@@ -402,6 +395,7 @@ meta_x11_selection_input_stream_xevent (MetaX11SelectionInputStream *stream,
   GBytes *bytes;
   Atom type;
   gint format;
+  char *target;
 
   xdisplay = priv->x11_display->xdisplay;
   xwindow = priv->window;
@@ -459,11 +453,13 @@ meta_x11_selection_input_stream_xevent (MetaX11SelectionInputStream *stream,
 
         if (xevent->xselection.property == None)
           {
+            target = XGetAtomName (xdisplay, priv->xtarget);
             g_task_return_new_error (task,
                                      G_IO_ERROR,
                                      G_IO_ERROR_NOT_FOUND,
-                                     _("Format %s not supported"), priv->target);
+                                     _("Format %s not supported"), target);
             meta_x11_selection_input_stream_complete (stream);
+            XFree (target);
           }
         else
           {
@@ -528,12 +524,9 @@ meta_x11_selection_input_stream_new_async (MetaX11Display      *x11_display,
   priv->x11_display = x11_display;
   x11_display->selection.input_streams =
     g_list_prepend (x11_display->selection.input_streams, stream);
-  priv->selection = g_strdup (selection);
-  priv->xselection = XInternAtom (x11_display->xdisplay, priv->selection, False);
-  priv->target = g_strdup (target);
-  priv->xtarget = XInternAtom (x11_display->xdisplay, priv->target, False);
-  priv->property = g_strdup_printf ("META_SELECTION_%p", stream);
-  priv->xproperty = XInternAtom (x11_display->xdisplay, priv->property, False);
+  priv->xselection = XInternAtom (x11_display->xdisplay, selection, False);
+  priv->xtarget = XInternAtom (x11_display->xdisplay, target, False);
+  priv->xproperty = XInternAtom (x11_display->xdisplay, "META_SELECTION", False);
   priv->window = XCreateWindow (x11_display->xdisplay,
                                 x11_display->xroot,
                                 -1, -1, 1, 1,