Allow enabling or disabling *Statistics while Tor is running.

With this patch we stop scheduling when we should write statistics using a
single timestamp in run_scheduled_events(). Instead, we remember when a
statistics interval starts separately for each statistic type in geoip.c
and rephist.c. Every time run_scheduled_events() tries to write stats to
disk, it learns when it should schedule the next such attempt.

This patch also enables all statistics to be stopped and restarted at a
later time.

This patch comes with a few refactorings, some of which were not easily
doable without the patch.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/or/or.h b/src/or/or.h
index 572dc8b96d..e1f4541a7e 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3265,6 +3265,8 @@ typedef enum {
   DIRREQ_OR_CONN_BUFFER_FLUSHED = 4
 } dirreq_state_t;
 
+#define WRITE_STATS_INTERVAL (24*60*60)
+
 /********************************* microdesc.c *************************/
 
 typedef struct microdesc_cache_t microdesc_cache_t;