networkd: move event loop handling out of the manager (#4723)

This will allow us to have several managers sharing an event loop
and running in parallel, as if they were running in separate processes.

The long term-aim is to allow networkd to be split into separate
processes, so restructure the code to make this simpler.

For now we drop the exit-on-idle logic, as this was anyway severely
restricted at the moment. Once split, we will revisit this as it may
then make more sense again.

src/network/networkd-manager.c

@@ -1042,7 +1042,7 @@ static int manager_dirty_handler(sd_event_source *s, void *userdata) {
         return 1;
 }
 
-int manager_new(Manager **ret) {
+int manager_new(Manager **ret, sd_event *event) {
         _cleanup_manager_free_ Manager *m = NULL;
         int r;
 
@@ -1054,14 +1054,7 @@ int manager_new(Manager **ret) {
         if (!m->state_file)
                 return -ENOMEM;
 
-        r = sd_event_default(&m->event);
-        if (r < 0)
-                return r;
-
-        sd_event_set_watchdog(m->event, true);
-
-        sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
-        sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
+        m->event = sd_event_ref(event);
 
         r = sd_event_add_post(m->event, NULL, manager_dirty_handler, m);
         if (r < 0)
@@ -1137,33 +1130,7 @@ void manager_free(Manager *m) {
         free(m);
 }
 
-static bool manager_check_idle(void *userdata) {
-        Manager *m = userdata;
-        Link *link;
-        Iterator i;
-
-        assert(m);
-
-        /* Check whether we are idle now. The only case when we decide to be idle is when there's only a loopback
-         * device around, for which we have no configuration, and which already left the PENDING state. In all other
-         * cases we are not idle. */
-
-        HASHMAP_FOREACH(link, m->links, i) {
-                /* We are not woken on udev activity, so let's just wait for the pending udev event */
-                if (link->state == LINK_STATE_PENDING)
-                        return false;
-
-                if ((link->flags & IFF_LOOPBACK) == 0)
-                        return false;
-
-                if (link->network)
-                        return false;
-        }
-
-        return true;
-}
-
-int manager_run(Manager *m) {
+int manager_start(Manager *m) {
         Link *link;
         Iterator i;
 
@@ -1177,18 +1144,7 @@ int manager_run(Manager *m) {
         HASHMAP_FOREACH(link, m->links, i)
                 link_save(link);
 
-        if (m->bus)
-                return bus_event_loop_with_idle(
-                                m->event,
-                                m->bus,
-                                "org.freedesktop.network1",
-                                DEFAULT_EXIT_USEC,
-                                manager_check_idle,
-                                m);
-        else
-                /* failed to connect to the bus, so we lose exit-on-idle logic,
-                   this should not happen except if dbus is not around at all */
-                return sd_event_loop(m->event);
+        return 0;
 }
 
 int manager_load_config(Manager *m) {

src/network/networkd-manager.h

@@ -76,11 +76,11 @@ static inline const DUID* link_duid(const Link *link) {
 
 extern const sd_bus_vtable manager_vtable[];
 
-int manager_new(Manager **ret);
+int manager_new(Manager **ret, sd_event *event);
 void manager_free(Manager *m);
 
 int manager_connect_bus(Manager *m);
-int manager_run(Manager *m);
+int manager_start(Manager *m);
 
 int manager_load_config(Manager *m);
 bool manager_should_reload(Manager *m);

src/network/networkd.c

@@ -18,6 +18,7 @@
 ***/
 
 #include "sd-daemon.h"
+#include "sd-event.h"
 
 #include "capability-util.h"
 #include "networkd-conf.h"
@@ -26,6 +27,7 @@
 #include "user-util.h"
 
 int main(int argc, char *argv[]) {
+        sd_event *event = NULL;
         _cleanup_manager_free_ Manager *m = NULL;
         const char *user = "systemd-network";
         uid_t uid;
@@ -78,7 +80,15 @@ int main(int argc, char *argv[]) {
 
         assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);
 
-        r = manager_new(&m);
+        r = sd_event_default(&event);
+        if (r < 0)
+                goto out;
+
+        sd_event_set_watchdog(event, true);
+        sd_event_add_signal(event, NULL, SIGTERM, NULL, NULL);
+        sd_event_add_signal(event, NULL, SIGINT, NULL, NULL);
+
+        r = manager_new(&m, event);
         if (r < 0) {
                 log_error_errno(r, "Could not create manager: %m");
                 goto out;
@@ -118,22 +128,29 @@ int main(int argc, char *argv[]) {
                 goto out;
         }
 
+        r = manager_start(m);
+        if (r < 0) {
+                log_error_errno(r, "Could not start manager: %m");
+                goto out;
+        }
+
         log_info("Enumeration completed");
 
         sd_notify(false,
                   "READY=1\n"
                   "STATUS=Processing requests...");
 
-        r = manager_run(m);
+        r = sd_event_loop(event);
         if (r < 0) {
                 log_error_errno(r, "Event loop failed: %m");
                 goto out;
         }
-
 out:
         sd_notify(false,
                   "STOPPING=1\n"
                   "STATUS=Shutting down...");
 
+        sd_event_unref(event);
+
         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }

src/network/test-network.c

@@ -186,6 +186,7 @@ static void test_address_equality(void) {
 
 int main(void) {
         _cleanup_manager_free_ Manager *manager = NULL;
+        sd_event *event;
         struct udev *udev;
         struct udev_device *loopback;
         int r;
@@ -194,11 +195,16 @@ int main(void) {
         test_deserialize_dhcp_routes();
         test_address_equality();
 
-        assert_se(manager_new(&manager) >= 0);
+        r = sd_event_default(&event);
+        assert_se(r >= 0);
+
+        assert_se(manager_new(&manager, event) >= 0);
 
         r = test_load_config(manager);
-        if (r == -EPERM)
+        if (r == -EPERM) {
+                sd_event_unref(event);
                 return EXIT_TEST_SKIP;
+        }
 
         udev = udev_new();
         assert_se(udev);
@@ -213,4 +219,5 @@ int main(void) {
 
         udev_device_unref(loopback);
         udev_unref(udev);
+        sd_event_unref(event);
 }