From bb9c5ed7aaa92319978f318bad66be5568bea003 Mon Sep 17 00:00:00 2001
From: Julius Volz <julius@soundcloud.com>
Date: Sat, 16 Mar 2013 01:19:21 -0700
Subject: [PATCH] Fix nil pointer exception in frontier building.

---
 storage/metric/frontier.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/storage/metric/frontier.go b/storage/metric/frontier.go
index 3f3a4d7fe..1cf9bac3b 100644
--- a/storage/metric/frontier.go
+++ b/storage/metric/frontier.go
@@ -44,7 +44,7 @@ func (f *diskFrontier) ContainsFingerprint(fingerprint model.Fingerprint) bool {
 
 func newDiskFrontier(i iterator) (d *diskFrontier, err error) {
 	i.SeekToLast()
-	if i.Key() == nil {
+	if !i.Valid() || i.Key() == nil {
 		return
 	}
 	lastKey, err := extractSampleKey(i)