libnm: expose nm_context_busy_watcher_integrate_source() as internal API for reuse

This will also be useful for NMSecretAgentOld.

The mechanics how NMClient handles the GMainContext and the
context-busy-watcher apply really to every GObject that uses
GDBusConnection and registers to signals.

At least, as long as the API provides no shutdown/stop method,
because that means shutdown/stop happens when unreferencing the
instance, at which point pending operations get cancelled (but
they cannot complete right away due to the nature of GTask and
g_dbus_connection_call()). If there is a shutdown/stop API, then all
pending operations could keep the instance alive, and the instance
would sticks around (and keeps the GMainContext busy) until shutdown is
completed. Basically, then the instance could be the context-busy-watcher
itself.

But in existing API which does not require the user to explicitly shutdown,
that is not a feasible (backward compatible) addition. But the context-busy-watcher
object is.

2 files changed, 31 insertions, 15 deletions

diff --git a/libnm/nm-client.c b/libnm/nm-client.c
index 7cb2cc5aaf..47be50e7cd 100644
--- a/libnm/nm-client.c
+++ b/libnm/nm-client.c
@@ -60,7 +60,7 @@
 
 /*****************************************************************************/
 
-static NM_CACHED_QUARK_FCN ("nm-client-context-busy-watcher", nm_client_context_busy_watcher_quark)
+NM_CACHED_QUARK_FCN ("nm-context-busy-watcher", nm_context_busy_watcher_quark)
 
 static void
 _context_busy_watcher_attach_integration_source_cb (gpointer data,
@@ -69,10 +69,21 @@ _context_busy_watcher_attach_integration_source_cb (gpointer data,
 	nm_g_source_destroy_and_unref (data);
 }
 
-static void
-_context_busy_watcher_attach_integration_source (GObject *context_busy_watcher,
-                                                 GSource *source_take)
+void
+nm_context_busy_watcher_integrate_source (GMainContext *outer_context,
+                                          GMainContext *inner_context,
+                                          GObject *context_busy_watcher)
 {
+	GSource *source;
+
+	nm_assert (outer_context);
+	nm_assert (inner_context);
+	nm_assert (outer_context != inner_context);
+	nm_assert (G_IS_OBJECT (context_busy_watcher));
+
+	source = nm_utils_g_main_context_create_integrate_source (inner_context);
+	g_source_attach (source, outer_context);
+
 	/* The problem is...
 	 *
 	 * NMClient is associated with a GMainContext, just like its underlying GDBusConnection
@@ -114,7 +125,7 @@ _context_busy_watcher_attach_integration_source (GObject *context_busy_watcher,
 
 	g_object_weak_ref (context_busy_watcher,
 	                   _context_busy_watcher_attach_integration_source_cb,
-	                   source_take);
+	                   source);
 }
 
 /*****************************************************************************/
@@ -1008,7 +1019,7 @@ nm_client_get_context_busy_watcher (NMClient *self)
 	g_return_val_if_fail (NM_IS_CLIENT (self), NULL);
 
 	w = NM_CLIENT_GET_PRIVATE (self)->context_busy_watcher;
-	return    g_object_get_qdata (w, nm_client_context_busy_watcher_quark ())
+	return    g_object_get_qdata (w, nm_context_busy_watcher_quark ())
 	       ?: w;
 }
 
@@ -6816,7 +6827,7 @@ name_owner_changed (NMClient *self,
 
 		old_context_busy_watcher = g_steal_pointer (&priv->context_busy_watcher);
 		priv->context_busy_watcher = g_object_ref (g_object_get_qdata (old_context_busy_watcher,
-		                                                               nm_client_context_busy_watcher_quark ()));
+		                                                               nm_context_busy_watcher_quark ()));
 
 		g_main_context_ref (priv->main_context);
 		g_main_context_unref (priv->dbus_context);
@@ -7379,12 +7390,12 @@ init_sync (GInitable *initable, GCancellable *cancellable, GError **error)
 	 * to resync and drop the inner context. That means, requests made against the inner
 	 * context have a different lifetime. Hence, we create a separate tracking
 	 * object. This "wraps" the outer context-busy-watcher and references it, so
-	 * that the work together. Grep for nm_client_context_busy_watcher_quark() to
+	 * that the work together. Grep for nm_context_busy_watcher_quark() to
 	 * see how this works. */
 	parent_context_busy_watcher = g_steal_pointer (&priv->context_busy_watcher);
 	priv->context_busy_watcher = g_object_new (G_TYPE_OBJECT, NULL);
 	g_object_set_qdata_full (priv->context_busy_watcher,
-	                         nm_client_context_busy_watcher_quark (),
+	                         nm_context_busy_watcher_quark (),
 	                         parent_context_busy_watcher,
 	                         g_object_unref);
 
@@ -7403,12 +7414,9 @@ init_sync (GInitable *initable, GCancellable *cancellable, GError **error)
 	g_main_context_pop_thread_default (dbus_context);
 
 	if (priv->main_context != priv->dbus_context) {
-		GSource *source;
-
-		source = nm_utils_g_main_context_create_integrate_source (priv->dbus_context);
-		g_source_attach (source, priv->main_context);
-		_context_busy_watcher_attach_integration_source (priv->context_busy_watcher,
-		                                                 g_steal_pointer (&source));
+		nm_context_busy_watcher_integrate_source (priv->main_context,
+		                                          priv->dbus_context,
+		                                          priv->context_busy_watcher);
 	}
 
 	g_main_context_unref (dbus_context);
diff --git a/libnm/nm-libnm-utils.h b/libnm/nm-libnm-utils.h
index fd32b7c393..c8f0d29095 100644
--- a/libnm/nm-libnm-utils.h
+++ b/libnm/nm-libnm-utils.h
@@ -175,6 +175,14 @@ _nml_coerce_property_strv_not_null (char **strv)
 
 /*****************************************************************************/
 
+GQuark nm_context_busy_watcher_quark (void);
+
+void nm_context_busy_watcher_integrate_source (GMainContext *outer_context,
+                                               GMainContext *inner_context,
+                                               GObject *context_busy_watcher);
+
+/*****************************************************************************/
+
 typedef struct _NMLDBusObject     NMLDBusObject;
 typedef struct _NMLDBusObjWatcher NMLDBusObjWatcher;
 typedef struct _NMLDBusMetaIface  NMLDBusMetaIface;