libnm: add comment about context-busy-watcher and g_dbus_connection_signal_unsubscribe()

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Thomas Haller 2021-03-29 10:28:39 +02:00
parent 193a6ac3e5
commit 49d69bc1b0
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@ -7177,6 +7177,18 @@ nml_cleanup_context_busy_watcher_on_idle(GObject *context_busy_watcher_take, GMa
* no destroy notify to g_dbus_connection_signal_subscribe().
* That means, there should be no other unaccounted GSource'es left.
*
* Another reason is g_dbus_connection_signal_unsubscribe() which does
* not guarantee that everything was unsubscribed right away. Instead,
* there might still be idle actions queued (which will be thrown away
* once processed). Still, that means, the caller must continue to iterate
* the main context afterwards. Maybe we should pass a GDestroyNotify to
* g_dbus_connection_signal_subscribe() which handles an additional reference
* to the context_busy_watcher object. That would be the proper way to handle
* this. We don't do that, so in practice at this point there might still
* be some idle actions (with G_PRIORITY_DEFAULT) pending. As we schedule here
* another idle action with lower priority, we handle those cases without
* using a GDestroyNotify.
*
* However, we really need to be sure that the context_busy_watcher's
* lifetime matches the time that the context is busy. That is especially
* important with synchronous initialization, where the context-busy-watcher
@ -7198,7 +7210,13 @@ nml_cleanup_context_busy_watcher_on_idle(GObject *context_busy_watcher_take, GMa
* the user *MUST* always keep iterating the context after NMClient got destroyed.
* But that is not a severe limitation, because the user anyway must be prepared
* to do that. That is because in many cases it is necessary anyway (and the user
* wouldn't know a priory when not). This way, it is just always necessary. */
* wouldn't know a priory when not). This way, it is just always necessary.
*
* It might be nice to use G_DEFAULT_PRIORITY here to minimize how long the
* instance stays alive. Probably that would be fine, even without passing
* a GDestroyNotify to g_dbus_connection_signal_subscribe(). But to be extra
* careful, use a low priority.
**/
cleanup_source =
nm_g_idle_source_new(G_PRIORITY_LOW + 10,