From: dv1tas <dv1tas@fbe50366-0c72-4402-a84b-5d246361dba7>
Date: Fri, 14 Jun 2013 08:54:49 +0000 (+0000)
Subject: Fix jitter in computing one-second interval
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ea15ac2e17b572bfaba79d4a8e7136f6cba95c63;p=people%2Fms%2Fmstpd.git

Fix jitter in computing one-second interval

Signed-off-by: Jorge Gastón
Signed-off-by: Vitalii Demianets


git-svn-id: svn://svn.code.sf.net/p/mstpd/code/trunk@45 fbe50366-0c72-4402-a84b-5d246361dba7
---

diff --git a/epoll_loop.c b/epoll_loop.c
index d5b3b01..e8c0556 100644
--- a/epoll_loop.c
+++ b/epoll_loop.c
@@ -94,7 +94,6 @@ static inline int time_diff(struct timeval *second, struct timeval *first)
 static inline void run_timeouts(void)
 {
     bridge_one_second();
-    gettimeofday(&nexttimeout, NULL);
     ++(nexttimeout.tv_sec);
 }
 
@@ -116,6 +115,22 @@ int epoll_main_loop(void)
         if(timeout < 0 || timeout > 1000)
         {
             run_timeouts();
+            /*
+             * Check if system time has changed.
+             * NOTE: we can not differentiate reliably if system
+             * time has changed or we have spent too much time
+             * inside event handlers and run_timeouts().
+             * Fix: use clock_gettime(CLOCK_MONOTONIC, ) instead of
+             * gettimeofday, if it is available.
+             * If it is not available on given system -
+             * the following is the best we can do.
+             */
+            if(timeout < -4000 || timeout > 1000)
+            {
+                /* Most probably, system time has changed */
+                nexttimeout.tv_usec = tv.tv_usec;
+                nexttimeout.tv_sec = tv.tv_sec + 1;
+            }
             timeout = 0;
         }