Add MainloopStats option.

This patch adds support for MainloopStats that allow developers to get
main event loop statistics via Tor's heartbeat status messages. The new
status log message will show how many succesful, erroneous, and idle
event loop iterations we have had.

See: https://bugs.torproject.org/24605

1 files changed, 14 insertions, 0 deletions

diff --git a/src/or/status.c b/src/or/status.c
index f7be41e412..1a8885e83e 100644
--- a/src/or/status.c
+++ b/src/or/status.c
@@ -157,6 +157,20 @@ log_heartbeat(time_t now)
     tor_free(msg);
   }
 
+  if (options->MainloopStats) {
+    const uint64_t main_loop_success_count = get_main_loop_success_count();
+    const uint64_t main_loop_error_count = get_main_loop_error_count();
+    const uint64_t main_loop_idle_count = get_main_loop_idle_count();
+
+    log_fn(LOG_NOTICE, LD_HEARTBEAT, "Main event loop statistics: "
+         U64_FORMAT " succesful returns, "
+         U64_FORMAT " erroneous returns, and "
+         U64_FORMAT " idle returns.",
+         U64_PRINTF_ARG(main_loop_success_count),
+         U64_PRINTF_ARG(main_loop_error_count),
+         U64_PRINTF_ARG(main_loop_idle_count));
+  }
+
   tor_free(uptime);
   tor_free(bw_sent);
   tor_free(bw_rcvd);