From 68d4ec3e13b73b74e7d178289e47f8db3c03ec5e Mon Sep 17 00:00:00 2001
From: Brandon Philips <brandon.philips@coreos.com>
Date: Sat, 12 Sep 2015 12:17:02 -0700
Subject: [PATCH] raft: improve panic error message

Give a human being some insight into how we might have gotten to this
state based on feedback from #3504.
---
 raft/log.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/raft/log.go b/raft/log.go
index e171d36ea..b5f0b46c5 100644
--- a/raft/log.go
+++ b/raft/log.go
@@ -181,7 +181,7 @@ func (l *raftLog) commitTo(tocommit uint64) {
 	// never decrease commit
 	if l.committed < tocommit {
 		if l.lastIndex() < tocommit {
-			l.logger.Panicf("tocommit(%d) is out of range [lastIndex(%d)]", tocommit, l.lastIndex())
+			l.logger.Panicf("tocommit(%d) is out of range [lastIndex(%d)]. Was the raft log corrupted, truncated, or lost?", tocommit, l.lastIndex())
 		}
 		l.committed = tocommit
 	}