diff --git a/vendor/github.com/coreos/etcd/raft/util.go b/vendor/github.com/coreos/etcd/raft/util.go
new file mode 100644
index 0000000..f4141fe
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/raft/util.go
@@ -0,0 +1,129 @@
+// Copyright 2015 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package raft
+
+import (
+	"bytes"
+	"fmt"
+
+	pb "github.com/coreos/etcd/raft/raftpb"
+)
+
+func (st StateType) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf("%q", st.String())), nil
+}
+
+// uint64Slice implements sort interface
+type uint64Slice []uint64
+
+func (p uint64Slice) Len() int           { return len(p) }
+func (p uint64Slice) Less(i, j int) bool { return p[i] < p[j] }
+func (p uint64Slice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+
+func min(a, b uint64) uint64 {
+	if a > b {
+		return b
+	}
+	return a
+}
+
+func max(a, b uint64) uint64 {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func IsLocalMsg(msgt pb.MessageType) bool {
+	return msgt == pb.MsgHup || msgt == pb.MsgBeat || msgt == pb.MsgUnreachable ||
+		msgt == pb.MsgSnapStatus || msgt == pb.MsgCheckQuorum
+}
+
+func IsResponseMsg(msgt pb.MessageType) bool {
+	return msgt == pb.MsgAppResp || msgt == pb.MsgVoteResp || msgt == pb.MsgHeartbeatResp || msgt == pb.MsgUnreachable || msgt == pb.MsgPreVoteResp
+}
+
+// voteResponseType maps vote and prevote message types to their corresponding responses.
+func voteRespMsgType(msgt pb.MessageType) pb.MessageType {
+	switch msgt {
+	case pb.MsgVote:
+		return pb.MsgVoteResp
+	case pb.MsgPreVote:
+		return pb.MsgPreVoteResp
+	default:
+		panic(fmt.Sprintf("not a vote message: %s", msgt))
+	}
+}
+
+// EntryFormatter can be implemented by the application to provide human-readable formatting
+// of entry data. Nil is a valid EntryFormatter and will use a default format.
+type EntryFormatter func([]byte) string
+
+// DescribeMessage returns a concise human-readable description of a
+// Message for debugging.
+func DescribeMessage(m pb.Message, f EntryFormatter) string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "%x->%x %v Term:%d Log:%d/%d", m.From, m.To, m.Type, m.Term, m.LogTerm, m.Index)
+	if m.Reject {
+		fmt.Fprintf(&buf, " Rejected")
+		if m.RejectHint != 0 {
+			fmt.Fprintf(&buf, "(Hint:%d)", m.RejectHint)
+		}
+	}
+	if m.Commit != 0 {
+		fmt.Fprintf(&buf, " Commit:%d", m.Commit)
+	}
+	if len(m.Entries) > 0 {
+		fmt.Fprintf(&buf, " Entries:[")
+		for i, e := range m.Entries {
+			if i != 0 {
+				buf.WriteString(", ")
+			}
+			buf.WriteString(DescribeEntry(e, f))
+		}
+		fmt.Fprintf(&buf, "]")
+	}
+	if !IsEmptySnap(m.Snapshot) {
+		fmt.Fprintf(&buf, " Snapshot:%v", m.Snapshot)
+	}
+	return buf.String()
+}
+
+// DescribeEntry returns a concise human-readable description of an
+// Entry for debugging.
+func DescribeEntry(e pb.Entry, f EntryFormatter) string {
+	var formatted string
+	if e.Type == pb.EntryNormal && f != nil {
+		formatted = f(e.Data)
+	} else {
+		formatted = fmt.Sprintf("%q", e.Data)
+	}
+	return fmt.Sprintf("%d/%d %s %s", e.Term, e.Index, e.Type, formatted)
+}
+
+func limitSize(ents []pb.Entry, maxSize uint64) []pb.Entry {
+	if len(ents) == 0 {
+		return ents
+	}
+	size := ents[0].Size()
+	var limit int
+	for limit = 1; limit < len(ents); limit++ {
+		size += ents[limit].Size()
+		if uint64(size) > maxSize {
+			break
+		}
+	}
+	return ents[:limit]
+}