+ assert(t->state == TIMER_DEAD);
+
+ if (t->deserialized_state != t->state) {
+
+ if (t->deserialized_state == TIMER_WAITING ||
+ t->deserialized_state == TIMER_RUNNING ||
+ t->deserialized_state == TIMER_ELAPSED)
+ timer_enter_waiting(t, false);
+ else
+ timer_set_state(t, t->deserialized_state);
+ }
+
+ return 0;
+}
+
+static void timer_enter_dead(Timer *t, bool success) {
+ assert(t);
+
+ if (!success)
+ t->failure = true;
+
+ timer_set_state(t, t->failure ? TIMER_MAINTENANCE : TIMER_DEAD);
+}
+
+static void timer_enter_waiting(Timer *t, bool initial) {
+ TimerValue *v;
+ usec_t base = 0, delay, n;
+ bool found = false;
+ int r;
+
+ n = now(CLOCK_MONOTONIC);
+
+ LIST_FOREACH(value, v, t->values) {
+
+ if (v->disabled)
+ continue;
+
+ switch (v->base) {
+
+ case TIMER_ACTIVE:
+ if (state_translation_table[t->state] == UNIT_ACTIVE) {
+ base = t->meta.inactive_exit_timestamp.monotonic;
+ } else
+ base = n;
+ break;
+
+ case TIMER_BOOT:
+ /* CLOCK_MONOTONIC equals the uptime on Linux */
+ base = 0;
+ break;
+
+ case TIMER_STARTUP:
+ base = t->meta.manager->startup_timestamp.monotonic;
+ break;
+
+ case TIMER_UNIT_ACTIVE:
+
+ if (t->unit->meta.inactive_exit_timestamp.monotonic <= 0)
+ continue;
+
+ base = t->unit->meta.inactive_exit_timestamp.monotonic;
+ break;
+
+ case TIMER_UNIT_INACTIVE:
+
+ if (t->unit->meta.inactive_enter_timestamp.monotonic <= 0)
+ continue;
+
+ base = t->unit->meta.inactive_enter_timestamp.monotonic;
+ break;
+
+ default:
+ assert_not_reached("Unknown timer base");
+ }
+
+ v->next_elapse = base + v->value;
+
+ if (!initial && v->next_elapse < n) {
+ v->disabled = true;
+ continue;
+ }
+
+ if (!found)
+ t->next_elapse = v->next_elapse;
+ else
+ t->next_elapse = MIN(t->next_elapse, v->next_elapse);
+
+ found = true;
+ }
+
+ if (!found) {
+ timer_set_state(t, TIMER_ELAPSED);
+ return;
+ }
+
+ delay = n < t->next_elapse ? t->next_elapse - n : 0;
+
+ if ((r = unit_watch_timer(UNIT(t), delay, &t->timer_watch)) < 0)
+ goto fail;
+
+ timer_set_state(t, TIMER_WAITING);
+ return;
+
+fail:
+ log_warning("%s failed to enter waiting state: %s", t->meta.id, strerror(-r));
+ timer_enter_dead(t, false);
+}
+
+static void timer_enter_running(Timer *t) {
+ int r;
+ assert(t);
+
+ if ((r = manager_add_job(UNIT(t)->meta.manager, JOB_START, t->unit, JOB_REPLACE, true, NULL)) < 0)
+ goto fail;
+
+ timer_set_state(t, TIMER_RUNNING);
+ return;
+
+fail:
+ log_warning("%s failed to queue unit startup job: %s", t->meta.id, strerror(-r));
+ timer_enter_dead(t, false);
+}
+
+static int timer_start(Unit *u) {
+ Timer *t = TIMER(u);
+
+ assert(t);
+ assert(t->state == TIMER_DEAD || t->state == TIMER_MAINTENANCE);
+
+ if (t->unit->meta.load_state != UNIT_LOADED)
+ return -ENOENT;
+
+ t->failure = false;
+ timer_enter_waiting(t, true);
+ return 0;
+}
+
+static int timer_stop(Unit *u) {
+ Timer *t = TIMER(u);
+
+ assert(t);
+ assert(t->state == TIMER_WAITING || t->state == TIMER_RUNNING || t->state == TIMER_ELAPSED);
+
+ timer_enter_dead(t, true);
+ return 0;
+}
+
+static int timer_serialize(Unit *u, FILE *f, FDSet *fds) {
+ Timer *t = TIMER(u);
+
+ assert(u);
+ assert(f);
+ assert(fds);
+
+ unit_serialize_item(u, f, "state", timer_state_to_string(t->state));
+
+ return 0;
+}
+
+static int timer_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
+ Timer *t = TIMER(u);
+
+ assert(u);
+ assert(key);
+ assert(value);
+ assert(fds);
+
+ if (streq(key, "state")) {
+ TimerState state;
+
+ if ((state = timer_state_from_string(value)) < 0)
+ log_debug("Failed to parse state value %s", value);
+ else
+ t->deserialized_state = state;
+ } else
+ log_debug("Unknown serialization key '%s'", key);
+
+ return 0;