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gmain: get rid of poll_waiting

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This variable, which is the cause of much grief, exists for two reasons:

  - ensuring the the wakeup pipe doesn't fill up

  - preventing the first poll() after adding a source from waking up
    immediately

The first point is no longer an issue with GWakeup.

The second point is addressed by using different logic: we only signal a
wakeup in the case that the context is currently acquired by a thread
that is not us.

As an added bonus, we can now implement g_main_context_wakeup() without
taking a lock.

https://bugzilla.gnome.org/show_bug.cgi?id=583511
https://bugzilla.gnome.org/show_bug.cgi?id=320888
This commit is contained in:
Ryan Lortie 2011-09-09 21:40:05 -04:00
parent e15d5313af
commit 1c8c408c51
1 changed files with 10 additions and 34 deletions
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42
glib/gmain.c
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@ -238,7 +238,6 @@ struct _GMainContext
GWakeup *wakeup; GWakeup *wakeup;
GPollFD wake_up_rec; GPollFD wake_up_rec;
gboolean poll_waiting;
/* Flag indicating whether the set of fd's changed during a poll */ /* Flag indicating whether the set of fd's changed during a poll */
gboolean poll_changed; gboolean poll_changed;
@ -343,7 +342,6 @@ static void g_main_context_add_poll_unlocked (GMainContext *context,
GPollFD *fd); GPollFD *fd);
static void g_main_context_remove_poll_unlocked (GMainContext *context, static void g_main_context_remove_poll_unlocked (GMainContext *context,
GPollFD *fd); GPollFD *fd);
static void g_main_context_wakeup_unlocked (GMainContext *context);
static gboolean g_timeout_prepare (GSource *source, static gboolean g_timeout_prepare (GSource *source,
gint *timeout); gint *timeout);
@ -893,8 +891,11 @@ g_source_attach (GSource *source,
result = g_source_attach_unlocked (source, context); result = g_source_attach_unlocked (source, context);
/* Now wake up the main loop if it is waiting in the poll() */ /* If another thread has acquired the context, wake it up since it
g_main_context_wakeup_unlocked (context); * might be in poll() right now.
*/
if (context->owner && context->owner != G_THREAD_SELF)
g_wakeup_signal (context->wakeup);
UNLOCK_CONTEXT (context); UNLOCK_CONTEXT (context);
@ -2625,15 +2626,6 @@ g_main_context_prepare (GMainContext *context,
return FALSE; return FALSE;
} }
if (context->poll_waiting)
{
g_warning("g_main_context_prepare(): main loop already active in another thread");
UNLOCK_CONTEXT (context);
return FALSE;
}
context->poll_waiting = TRUE;
#if 0 #if 0
/* If recursing, finish up current dispatch, before starting over */ /* If recursing, finish up current dispatch, before starting over */
if (context->pending_dispatches) if (context->pending_dispatches)
@ -2828,8 +2820,6 @@ g_main_context_check (GMainContext *context,
if (context->wake_up_rec.events) if (context->wake_up_rec.events)
g_wakeup_acknowledge (context->wakeup); g_wakeup_acknowledge (context->wakeup);
context->poll_waiting = FALSE;
/* If the set of poll file descriptors changed, bail out /* If the set of poll file descriptors changed, bail out
* and let the main loop rerun * and let the main loop rerun
*/ */
@ -3221,7 +3211,7 @@ g_main_loop_quit (GMainLoop *loop)
LOCK_CONTEXT (loop->context); LOCK_CONTEXT (loop->context);
loop->is_running = FALSE; loop->is_running = FALSE;
g_main_context_wakeup_unlocked (loop->context); g_wakeup_signal (loop->context->wakeup);
if (loop->context->cond) if (loop->context->cond)
g_cond_broadcast (loop->context->cond); g_cond_broadcast (loop->context->cond);
@ -3422,7 +3412,7 @@ g_main_context_add_poll_unlocked (GMainContext *context,
context->poll_changed = TRUE; context->poll_changed = TRUE;
/* Now wake up the main loop if it is waiting in the poll() */ /* Now wake up the main loop if it is waiting in the poll() */
g_main_context_wakeup_unlocked (context); g_wakeup_signal (context->wakeup);
} }
/** /**
@ -3484,7 +3474,7 @@ g_main_context_remove_poll_unlocked (GMainContext *context,
context->poll_changed = TRUE; context->poll_changed = TRUE;
/* Now wake up the main loop if it is waiting in the poll() */ /* Now wake up the main loop if it is waiting in the poll() */
g_main_context_wakeup_unlocked (context); g_wakeup_signal (context->wakeup);
} }
/** /**
@ -3602,18 +3592,6 @@ g_main_context_get_poll_func (GMainContext *context)
return result; return result;
} }
/* HOLDS: context's lock */
/* Wake the main loop up from a poll() */
static void
g_main_context_wakeup_unlocked (GMainContext *context)
{
if (context->poll_waiting)
{
context->poll_waiting = FALSE;
g_wakeup_signal (context->wakeup);
}
}
/** /**
* g_main_context_wakeup: * g_main_context_wakeup:
* @context: a #GMainContext * @context: a #GMainContext
@ -3629,9 +3607,7 @@ g_main_context_wakeup (GMainContext *context)
g_return_if_fail (g_atomic_int_get (&context->ref_count) > 0); g_return_if_fail (g_atomic_int_get (&context->ref_count) > 0);
LOCK_CONTEXT (context); g_wakeup_signal (context->wakeup);
g_main_context_wakeup_unlocked (context);
UNLOCK_CONTEXT (context);
} }
/** /**