From eb0a19062eba79a39a57b9de1486c279e06eca4f Mon Sep 17 00:00:00 2001
From: Cameron Sparr <cameronsparr@gmail.com>
Date: Thu, 22 Oct 2015 10:55:26 -0600
Subject: [PATCH] When MongoDB freezes or restarts, do not report negative
 diffs

Fixes #253
---
 plugins/mongodb/mongostat.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/plugins/mongodb/mongostat.go b/plugins/mongodb/mongostat.go
index b3c990b1a..585512d88 100644
--- a/plugins/mongodb/mongostat.go
+++ b/plugins/mongodb/mongostat.go
@@ -367,7 +367,11 @@ func computeLockDiffs(prevLocks, curLocks map[string]LockUsage) []LockUsage {
 }
 
 func diff(newVal, oldVal, sampleTime int64) int64 {
-	return (newVal - oldVal) / sampleTime
+	d := newVal - oldVal
+	if d <= 0 {
+		d = newVal
+	}
+	return d / sampleTime
 }
 
 // NewStatLine constructs a StatLine object from two ServerStatus objects.