glib: fix high cpu load in some apps

Closes #6388
Fixes #6375

srcpkgs/glib/patches/5d74233476d61771b4d67d50bec5420f551ef922.patch

@@ -0,0 +1,103 @@
+From 5d74233476d61771b4d67d50bec5420f551ef922 Mon Sep 17 00:00:00 2001
+From: Paolo Bonzini <pbonzini@redhat.com>
+Date: Tue, 4 Apr 2017 09:56:47 +0200
+Subject: [PATCH] gmain: only signal GWakeup right before or during a blocking
+ poll
+
+Since commit e4ee307 ("Do not wake up main loop if change is from same
+thread", bug 761102), GMainContext uses context->owner to decide if the
+event loop is being run in the current thread.  However, what really
+matters is the phase in the prepare/query/poll/check/dispatch sequence.
+Wakeups are only needed between the end of prepare and the end of poll,
+and then only if prepare found that no sources were ready.
+
+There is no need to take threads into account, because prepare, check
+and all callers of conditional_wakeup all look at the new need_wakeup
+flag inside LOCK_CONTEXT/UNLOCK_CONTEXT.
+
+With this change, g_main_context_is_owner and g_main_context_wait are
+the only functions for which acquire/release matters, just like before
+commit e4ee307.
+
+Signed-off-by: Paolo Bonzini <bonzini@gnu.org>
+---
+ glib/gmain.c | 30 +++++++++++++++++++-----------
+ 1 file changed, 19 insertions(+), 11 deletions(-)
+
+diff --git a/glib/gmain.c b/glib/gmain.c
+index ab2908e..af0a29a 100644
+--- glib/gmain.c
++++ glib/gmain.c
+@@ -277,7 +277,8 @@ struct _GMainContext
+ 
+   guint next_id;
+   GList *source_lists;
+-  gint in_check_or_prepare;
++  gboolean in_check_or_prepare;
++  gboolean need_wakeup;
+ 
+   GPollRec *poll_records;
+   guint n_poll_records;
+@@ -651,6 +652,7 @@ g_main_context_new (void)
+   
+   context->pending_dispatches = g_ptr_array_new ();
+   
++  context->need_wakeup = FALSE;
+   context->time_is_fresh = FALSE;
+   
+   context->wakeup = g_wakeup_new ();
+@@ -1127,17 +1129,11 @@ source_remove_from_context (GSource      *source,
+ 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
++  /* This flag is set if at the start of prepare() we have no other ready
++   * sources, and hence would wait in poll(). In that case, any other threads
++   * attaching sources will need to signal a wakeup.
+    */
+-  if (context->owner != G_THREAD_SELF)
++  if (context->need_wakeup)
+     g_wakeup_signal (context->wakeup);
+ }
+ 
+@@ -3469,6 +3465,10 @@ g_main_context_prepare (GMainContext *context,
+   
+   LOCK_CONTEXT (context);
+ 
++  /* context->need_wakeup is protected by LOCK_CONTEXT/UNLOCK_CONTEXT,
++   * so need not set it yet.
++   */
++
+   context->time_is_fresh = FALSE;
+ 
+   if (context->in_check_or_prepare)
+@@ -3594,6 +3594,8 @@ g_main_context_prepare (GMainContext *context,
+ 	}
+     }
+   g_source_iter_clear (&iter);
++  /* See conditional_wakeup() where this is used */
++  context->need_wakeup = (n_ready == 0);
+ 
+   TRACE (GLIB_MAIN_CONTEXT_AFTER_PREPARE (context, current_priority, n_ready));
+ 
+@@ -3728,6 +3730,12 @@ g_main_context_check (GMainContext *context,
+ 
+   TRACE (GLIB_MAIN_CONTEXT_BEFORE_CHECK (context, max_priority, fds, n_fds));
+ 
++  /* We don't need to wakeup during check or dispatch, because
++   * all sources will be re-evaluated during prepare/query.
++   */
++  context->need_wakeup = FALSE;
++
++  /* And if we have a wakeup pending, acknowledge it */
+   for (i = 0; i < n_fds; i++)
+     {
+       if (fds[i].fd == context->wake_up_rec.fd)

srcpkgs/glib/template

@@ -1,7 +1,7 @@
 # Template build file for 'glib'
 pkgname=glib
 version=2.52.2
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--enable-libelf --disable-fam --with-pcre=system --enable-static"
 hostmakedepends="automake libtool pkg-config perl python libxslt docbook-xsl"