From 8d49f8dcec35c0e3483579b4f848de768ebd43e4 Mon Sep 17 00:00:00 2001
From: donker <donker@astron.nl>
Date: Wed, 29 Sep 2021 17:02:29 +0200
Subject: [PATCH] L2SDP-499, changes to prevent 100% load after returning from
 sleep/hibernate.

---
 src/sdptr.cpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/sdptr.cpp b/src/sdptr.cpp
index 4002c3b7..735da970 100644
--- a/src/sdptr.cpp
+++ b/src/sdptr.cpp
@@ -70,13 +70,25 @@ void monitor()
     pthread_cond_init(&SD.newpoint_cond, NULL);
 
     SD.uptime = 0;
-    
+
     gettimeofday(&current_time, NULL);
     SD.start_time = current_time.tv_sec;
 
 
     while (ServerRunning) {
+        struct timespec current_time_timespec;
+        clock_gettime(CLOCK_REALTIME, (struct timespec *)&current_time_timespec);
+
         SD.t0.tv_sec = SD.t0.tv_sec + SD.timetick;  // specify next position in time
+        if (SD.t0.tv_sec < current_time_timespec.tv_sec) {
+            // skip ahead if we already are beyond the next tick.
+            // this prevents us from trying to catch up if the host system
+            // was in hibernation or this process was otherwise suspended.
+            // this means that SD.uptime will reflect the number of seconds
+            // this process was actually running, and now - SD.start_time
+            // reflects the wall-clock time that passed since start.
+            SD.t0.tv_sec = current_time_timespec.tv_sec + SD.timetick;
+        }
         SD.t0.tv_nsec = 10000000L;  // 0..999999999 // offset 10ms in a new second
         pthread_mutex_lock(&SD.newpoint_lock);
         pthread_cond_timedwait(&SD.newpoint_cond, &SD.newpoint_lock, (const struct timespec *)&SD.t0);
@@ -104,12 +116,12 @@ void server_init(bool warm_start)
     ConfigReader* p = ConfigReader::getInstance();  // create object of the class ConfigReader
     p->parseFile(SD.configfile);  // parse the configuration file
     p->dumpFileValues();  // print map on the console after parsing it
-    
+
     p->getValue(SD.ant_band_station_type, "n_fpgas", SD.n_fpgas);
     p->getValue(SD.ant_band_station_type, "first_fpga_nr", SD.first_fpga_nr);
     p->getValue(SD.ant_band_station_type, "n_beamsets", SD.n_beamsets);
     p->getValue(SD.ant_band_station_type, "ip_prefix", SD.ip_prefix);
-    
+
     if (SD.n_fpgas == 0) {
         cerr << "ERROR, no settings found for '" << SD.ant_band_station_type << "'" <<endl;
         exit(EXIT_FAILURE);
@@ -178,7 +190,7 @@ int main (int argc, char* argv[])
 
     SD.configfile = "/etc/sdptr.conf";
     SD.ant_band_station_type = "-";
-    
+
     // set default values
     SD.n_fpgas = 16;
     SD.first_fpga_nr = 0;
-- 
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