+++ /dev/null
-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: 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
---- a/glib/gmain.c
-+++ b/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)
---
-cgit v0.12
-