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gobject: don't freeze to queue notify event in g_object_notify_by_spec_internal()

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Previously:

- if the object is currently not frozen, we called
  g_object_notify_queue_freeze() once. Afterwards dispatch the event
  directly. This is probably the common case, and requires one
  notify_lock lock.

- if the object is currently frozen, we call
  g_object_notify_queue_freeze(), g_object_notify_queue_add().
  g_object_notify_queue_thaw().
  This required taking the notify_lock three times.

- if the object is currently not frozen and in_init, then we called
  g_object_notify_queue_freeze(), g_object_notify_queue_freeze(),
  g_object_notify_queue_add(). This also required to take
  the lock three times. There is another thaw at the end of
  object initialization.

That was because we first call g_object_notify_queue_freeze() to see
whether we are frozen. And depending on that, queue the event (and thaw
again).

Instead, g_object_notify_queue_add() can do the check and queueing in
one step. There is no need to call a freeze() to (conditionally) enqueue
a notification. Now only one lock is taken in all cases.

Also, g_object_notify_queue_freeze() and g_object_notify_queue_thaw()
both call g_datalist_id_get_data() (which also take a bit lock). As the
thaw is no longer necessary, the second lock is also saved.
This commit is contained in:
Thomas Haller 2023-12-14 12:02:23 +01:00
parent a2b467624b
commit 94c735a2aa
1 changed files with 34 additions and 26 deletions
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60
gobject/gobject.c
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@ -320,13 +320,41 @@ g_object_notify_queue_thaw (GObject *object,
g_free (free_me);
}
static void
static gboolean
g_object_notify_queue_add (GObject *object,
GObjectNotifyQueue *nqueue,
GParamSpec *pspec)
GParamSpec *pspec,
gboolean in_init)
{
G_LOCK(notify_lock);
if (!nqueue)
{
/* We are called without an nqueue. Figure out whether a notification
* should be queued. */
nqueue = g_datalist_id_get_data (&object->qdata, quark_notify_queue);
if (!nqueue)
{
if (!in_init)
{
/* We don't have a notify queue and are not in_init. The event
* is not to be queued. The caller will dispatch directly. */
G_UNLOCK (notify_lock);
return FALSE;
}
/* We are "in_init", but did not freeze the queue in g_object_init
* yet. Instead, we gained a notify handler in instance init, so now
* we need to freeze just-in-time.
*
* Note that this freeze will be balanced at the end of object
* initialization.
*/
nqueue = g_object_notify_queue_create_queue_frozen (object);
}
}
g_assert (nqueue->n_pspecs < 65535);
if (g_slist_find (nqueue->pspecs, pspec) == NULL)
@ -336,6 +364,8 @@ g_object_notify_queue_add (GObject *object,
}
G_UNLOCK(notify_lock);
return TRUE;
}
#ifdef G_ENABLE_DEBUG
@ -1506,29 +1536,7 @@ g_object_notify_by_spec_internal (GObject *object,
if (pspec != NULL && needs_notify)
{
GObjectNotifyQueue *nqueue;
gboolean need_thaw = TRUE;
/* conditional freeze: only increase freeze count if already frozen */
nqueue = g_object_notify_queue_freeze (object, TRUE);
if (in_init && !nqueue)
{
/* We did not freeze the queue in g_object_init, but
* we gained a notify handler in instance init, so
* now we need to freeze just-in-time
*/
nqueue = g_object_notify_queue_freeze (object, FALSE);
need_thaw = FALSE;
}
if (nqueue != NULL)
{
/* we're frozen, so add to the queue and release our freeze */
g_object_notify_queue_add (object, nqueue, pspec);
if (need_thaw)
g_object_notify_queue_thaw (object, nqueue, FALSE);
}
else
if (!g_object_notify_queue_add (object, NULL, pspec, in_init))
{
/*
* Coverity doesn’t understand the paired ref/unref here and seems to
@ -1825,7 +1833,7 @@ object_set_property (GObject *object,
if ((pspec->flags & (G_PARAM_EXPLICIT_NOTIFY | G_PARAM_READABLE)) == G_PARAM_READABLE &&
nqueue != NULL)
g_object_notify_queue_add (object, nqueue, pspec);
g_object_notify_queue_add (object, nqueue, pspec, FALSE);
}
static void