From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Wed, 31 Aug 2011 16:36:10 +0000 (+0200)
Subject: Check sample ordering on accumulation
X-Git-Tag: 1.27-pre1~37
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=b088b70f8256a135a3aec77962b72f0c68663f83;p=thirdparty%2Fchrony.git

Check sample ordering on accumulation

If the newly accumulated sample is not newer than than the last one,
discard the source history and start from scratch. This can happen after
loading an invalid dump or when the system clock was stepped.
---

diff --git a/sourcestats.c b/sourcestats.c
index 88e99114..c648dc91 100644
--- a/sourcestats.c
+++ b/sourcestats.c
@@ -239,10 +239,19 @@ SST_AccumulateSample(SST_Stats inst, struct timeval *sample_time,
 {
   int n, m;
 
+  /* Make room for the new sample */
   if (inst->n_samples == MAX_SAMPLES) {
     prune_register(inst, 1);
   }
 
+  /* Make sure it's newer than the last sample */
+  if (inst->n_samples &&
+      UTI_CompareTimevals(&inst->sample_times[inst->last_sample], sample_time) >= 0) {
+    LOG(LOGS_WARN, LOGF_SourceStats, "Out of order sample detected, discarding history for %s",
+        inst->ip_addr ? UTI_IPToString(inst->ip_addr) : UTI_RefidToString(inst->refid));
+    prune_register(inst, inst->n_samples);
+  }
+
   n = inst->last_sample = (inst->last_sample + 1) %
     (MAX_SAMPLES * REGRESS_RUNS_RATIO);
   m = n % MAX_SAMPLES;