Use Libevent 2.0's periodic timers where available.

These timers behave better with non-monotonic clocks than our old
ones, and also try harder to make once-per-second events get called
one second apart, rather than one-plus-epsilon seconds apart.

This fixes bug 943 for everybody using Libevent 2.0 or later.

1 files changed, 19 insertions, 22 deletions

diff --git a/src/or/main.c b/src/or/main.c
index 0c3e6d5425..0dcc45464a 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -33,7 +33,7 @@ static void dumpstats(int severity); /* log stats */
 static void conn_read_callback(int fd, short event, void *_conn);
 static void conn_write_callback(int fd, short event, void *_conn);
 static void signal_callback(int fd, short events, void *arg);
-static void second_elapsed_callback(int fd, short event, void *args);
+static void second_elapsed_callback(periodic_timer_t *timer, void *args);
 static int conn_close_if_marked(int i);
 static void connection_start_reading_from_linked_conn(connection_t *conn);
 static int connection_should_read_from_linked_conn(connection_t *conn);
@@ -1205,39 +1205,30 @@ run_scheduled_events(time_t now)
   }
 }
 
-/** Libevent timer: used to invoke second_elapsed_callback() once per
- * second. */
-static struct event *timeout_event = NULL;
+/** Timer: used to invoke second_elapsed_callback() once per second. */
+static periodic_timer_t *second_timer = NULL;
 /** Number of libevent errors in the last second: we die if we get too many. */
 static int n_libevent_errors = 0;
 
 /** Libevent callback: invoked once every second. */
 static void
-second_elapsed_callback(int fd, short event, void *args)
+second_elapsed_callback(periodic_timer_t *timer, void *arg)
 {
   /* XXXX This could be sensibly refactored into multiple callbacks, and we
    * could use Libevent's timers for this rather than checking the current
    * time against a bunch of timeouts every second. */
-  static struct timeval one_second;
   static time_t current_second = 0;
   time_t now;
   size_t bytes_written;
   size_t bytes_read;
   int seconds_elapsed;
   or_options_t *options = get_options();
-  (void)fd;
-  (void)event;
-  (void)args;
-  if (!timeout_event) {
-    timeout_event = tor_evtimer_new(tor_libevent_get_base(),
-                                    second_elapsed_callback, NULL);
-    one_second.tv_sec = 1;
-    one_second.tv_usec = 0;
-  }
+  (void)timer;
+  (void)arg;
 
   n_libevent_errors = 0;
 
-  /* log_fn(LOG_NOTICE, "Tick."); */
+  /* log_notice(LD_GENERAL, "Tick."); */
   now = time(NULL);
   update_approx_time(now);
 
@@ -1302,10 +1293,6 @@ second_elapsed_callback(int fd, short event, void *args)
   run_scheduled_events(now);
 
   current_second = now; /* remember which second it is, for next time */
-
-  if (event_add(timeout_event, &one_second))
-    log_err(LD_NET,
-            "Error from libevent when setting one-second timeout event");
 }
 
 #ifndef MS_WINDOWS
@@ -1492,7 +1479,17 @@ do_main_loop(void)
   }
 
   /* set up once-a-second callback. */
-  second_elapsed_callback(0,0,NULL);
+  if (! second_timer) {
+    struct timeval one_second;
+    one_second.tv_sec = 1;
+    one_second.tv_usec = 0;
+
+    second_timer = periodic_timer_new(tor_libevent_get_base(),
+                                      &one_second,
+                                      second_elapsed_callback,
+                                      NULL);
+    tor_assert(second_timer);
+  }
 
   for (;;) {
     if (nt_service_is_stopping())
@@ -2013,7 +2010,7 @@ tor_free_all(int postfork)
   smartlist_free(connection_array);
   smartlist_free(closeable_connection_lst);
   smartlist_free(active_linked_connection_lst);
-  tor_free(timeout_event);
+  periodic_timer_free(second_timer);
   if (!postfork) {
     release_lockfile();
   }