Enable/disable per-second callback as needed.

There are three cases where this can happen: changes in our
controller events, changes in our DisableNetwork setting, and
changes in our hibernation state.

Closes ticket 26063.

changes/ticket26063

@@ -0,0 +1,5 @@
+  o Major features (CPU usage, mobile):
+    - When Tor is disabled (via DisableNetwork or via hibernation), it
+      no longer needs to run any per-second events.  This change should
+      make it easier for mobile applications to disable Tor while the
+      device is sleeping, or Tor is not running.  Closes ticket 26063.

src/or/config.c

@@ -2001,6 +2001,9 @@ options_act(const or_options_t *old_options)
     finish_daemon(options->DataDirectory);
   }
 
+  /* See whether we need to enable/disable our once-a-second timer. */
+  reschedule_per_second_timer();
+
   /* We want to reinit keys as needed before we do much of anything else:
      keys are important, and other things can depend on them. */
   if (transition_affects_workers ||

src/or/control.c

@@ -277,6 +277,7 @@ control_update_global_event_mask(void)
   smartlist_t *conns = get_connection_array();
   event_mask_t old_mask, new_mask;
   old_mask = global_event_mask;
+  int any_old_per_sec_events = control_any_per_second_event_enabled();
 
   global_event_mask = 0;
   SMARTLIST_FOREACH(conns, connection_t *, _conn,
@@ -316,6 +317,10 @@ control_update_global_event_mask(void)
     uint64_t r, w;
     control_get_bytes_rw_last_sec(&r, &w);
   }
+  if (any_old_per_sec_events != control_any_per_second_event_enabled()) {
+    reschedule_per_second_timer();
+  }
+
 #undef NEWLY_ENABLED
 }
 

src/or/hibernate.c

@@ -1137,6 +1137,8 @@ on_hibernate_state_change(hibernate_state_t prev_state)
   if (prev_state != HIBERNATE_STATE_INITIAL) {
     rescan_periodic_events(get_options());
   }
+
+  reschedule_per_second_timer();
 }
 
 #ifdef TOR_UNIT_TESTS