[glib/glib-2-54] gmain: Partial revert of recent wakeup changes to gmain.c

[Philip Withnall <pwithnall src gnome org>]

commit 94b38beff1347ec4a733199f7a7abdacaa958678
Author: Philip Withnall <withnall endlessm com>
Date:   Wed Jan 17 11:38:50 2018 +0000

    gmain: Partial revert of recent wakeup changes to gmain.c
    
    This reverts the following commits (but keeps the other recent changes
    to gmain.c):
     • e4ee3079c Do not wake up main loop if change is from same thread
     • 208702404 main: Create a helper function for "owner wakeup" optimization
     • 0c0469b56 gmain: Signal wakeups if context has never been acquired as well
     • 9ba95e25b gmain: only signal GWakeup right before or during a blocking poll
    
    Some combination of them is causing problems with LibreOffice and/or
    WebKit, and the safest thing to do at the moment is revert them all
    until we work out what’s going on. The previous revert (4976e8109) was
    not sufficient (it fixed WebKit, but re-broken LibreOffice).
    
    By reverting, we gain some spurious wakeups, but avoid dropping
    necessary wakeups, which is presumably what’s causing problems in the
    other modules.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=761102

 glib/gmain.c |   33 +++++----------------------------
 1 files changed, 5 insertions(+), 28 deletions(-)
---
diff --git a/glib/gmain.c b/glib/gmain.c
index 8ca54de..67102cd 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -1118,29 +1118,6 @@ source_remove_from_context (GSource      *source,
     }
 }
 
-/* See https://bugzilla.gnome.org/show_bug.cgi?id=761102 for
- * the introduction of this.
- *
- * The main optimization is to avoid waking up the main
- * context if a change is made by the current owner.
- */
-static void
-conditional_wakeup (GMainContext *context)
-{
-  /* We want to signal wakeups in two cases:
-   *  1 When the context is owned by another thread
-   *  2 When the context owner is NULL (two subcases)
-   *   2a Possible if the context has never been acquired
-   *   2b Or if the context has no current owner
-   *
-   * At least case 2a) is necessary to ensure backwards compatibility with
-   * qemu's use of GMainContext.
-   * https://bugzilla.gnome.org/show_bug.cgi?id=761102#c14
-   */
-  if (context->owner != G_THREAD_SELF)
-    g_wakeup_signal (context->wakeup);
-}
-
 static guint
 g_source_attach_unlocked (GSource      *source,
                           GMainContext *context,
@@ -1187,8 +1164,8 @@ g_source_attach_unlocked (GSource      *source,
   /* If another thread has acquired the context, wake it up since it
    * might be in poll() right now.
    */
-  if (do_wakeup)
-    conditional_wakeup (context);
+  if (do_wakeup && context->owner && context->owner != G_THREAD_SELF)
+    g_wakeup_signal (context->wakeup);
 
   return source->source_id;
 }
@@ -1878,7 +1855,7 @@ g_source_set_ready_time (GSource *source,
     {
       /* Quite likely that we need to change the timeout on the poll */
       if (!SOURCE_BLOCKED (source))
-        conditional_wakeup (context);
+        g_wakeup_signal (context->wakeup);
       UNLOCK_CONTEXT (context);
     }
 }
@@ -4318,7 +4295,7 @@ g_main_context_add_poll_unlocked (GMainContext *context,
   context->poll_changed = TRUE;
 
   /* Now wake up the main loop if it is waiting in the poll() */
-  conditional_wakeup (context);
+  g_wakeup_signal (context->wakeup);
 }
 
 /**
@@ -4378,7 +4355,7 @@ g_main_context_remove_poll_unlocked (GMainContext *context,
   context->poll_changed = TRUE;
 
   /* Now wake up the main loop if it is waiting in the poll() */
-  conditional_wakeup (context);
+  g_wakeup_signal (context->wakeup);
 }
 
 /**