stats: Support regular stats flush

Reliable monitoring requires regular flush of all stat values, even
if they have not changed. Otherwise (1) the monitoring app has to
maintain state and (2) can go out of sync if it's restarted while
the app is still running.

Change-Id: I04f1e7bdf0d6f20e4f15571e94191de61c47ddad

1 files changed, 29 insertions, 0 deletions

diff --git a/src/stats.c b/src/stats.c
index 61b7df87..5954167a 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -341,6 +341,25 @@ int osmo_stats_set_interval(int interval)
 	return 0;
 }
 
+/*! Set the regular flush period for a given stats_reporter
+ *
+ * Send all stats even if they have not changed (i.e. force the flush)
+ * every N-th reporting interval. Set to 0 to disable regular flush,
+ * set to 1 to flush every time, set to 2 to flush every 2nd time, etc.
+ *  \param[in] srep stats_reporter to set flush period for
+ *  \param[in] period Reporting interval in seconds
+ *  \returns 0 on success; negative on error */
+int osmo_stats_reporter_set_flush_period(struct osmo_stats_reporter *srep, unsigned int period)
+{
+	srep->flush_period = period;
+	srep->flush_period_counter = 0;
+	/* force the flush now if it's not disabled by period=0 */
+	if (period > 0)
+		srep->force_single_flush = 1;
+
+	return 0;
+}
+
 /*! Set the name prefix of a given stats_reporter.
  *  \param[in] srep stats_reporter whose name prefix is to be set
  *  \param[in] prefix NAme perfix to pre-pend for any reported value
@@ -706,7 +725,17 @@ static void flush_all_reporters()
 			continue;
 
 		osmo_stats_reporter_send_buffer(srep);
+
+		/* reset force_single_flush first */
 		srep->force_single_flush = 0;
+		/* and schedule a new flush if it's time for it */
+		if (srep->flush_period > 0) {
+			srep->flush_period_counter++;
+			if (srep->flush_period_counter >= srep->flush_period) {
+				srep->force_single_flush = 1;
+				srep->flush_period_counter = 0;
+			}
+		}
 	}
 }