Merge pull request #7634 from heyitsanthony/election-rpc

Election RPC service

clientv3/concurrency/election.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 
 	v3 "github.com/coreos/etcd/clientv3"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/mvcc/mvccpb"
 	"golang.org/x/net/context"
 )
@@ -36,6 +37,7 @@ type Election struct {
 	leaderKey     string
 	leaderRev     int64
 	leaderSession *Session
+	hdr           *pb.ResponseHeader
 }
 
 // NewElection returns a new election on a given key prefix.
@@ -43,6 +45,16 @@ func NewElection(s *Session, pfx string) *Election {
 	return &Election{session: s, keyPrefix: pfx + "/"}
 }
 
+// ResumeElection initializes an election with a known leader.
+func ResumeElection(s *Session, pfx string, leaderKey string, leaderRev int64) *Election {
+	return &Election{
+		session:       s,
+		leaderKey:     leaderKey,
+		leaderRev:     leaderRev,
+		leaderSession: s,
+	}
+}
+
 // Campaign puts a value as eligible for the election. It blocks until
 // it is elected, an error occurs, or the context is cancelled.
 func (e *Election) Campaign(ctx context.Context, val string) error {
@@ -80,6 +92,7 @@ func (e *Election) Campaign(ctx context.Context, val string) error {
 		}
 		return err
 	}
+	e.hdr = resp.Header
 
 	return nil
 }
@@ -101,6 +114,8 @@ func (e *Election) Proclaim(ctx context.Context, val string) error {
 		e.leaderKey = ""
 		return ErrElectionNotLeader
 	}
+
+	e.hdr = tresp.Header
 	return nil
 }
 
@@ -110,23 +125,27 @@ func (e *Election) Resign(ctx context.Context) (err error) {
 		return nil
 	}
 	client := e.session.Client()
-	_, err = client.Delete(ctx, e.leaderKey)
+	cmp := v3.Compare(v3.CreateRevision(e.leaderKey), "=", e.leaderRev)
+	resp, err := client.Txn(ctx).If(cmp).Then(v3.OpDelete(e.leaderKey)).Commit()
+	if err == nil {
+		e.hdr = resp.Header
+	}
 	e.leaderKey = ""
 	e.leaderSession = nil
 	return err
 }
 
 // Leader returns the leader value for the current election.
-func (e *Election) Leader(ctx context.Context) (string, error) {
+func (e *Election) Leader(ctx context.Context) (*v3.GetResponse, error) {
 	client := e.session.Client()
 	resp, err := client.Get(ctx, e.keyPrefix, v3.WithFirstCreate()...)
 	if err != nil {
-		return "", err
+		return nil, err
 	} else if len(resp.Kvs) == 0 {
 		// no leader currently elected
-		return "", ErrElectionNoLeader
+		return nil, ErrElectionNoLeader
 	}
-	return string(resp.Kvs[0].Value), nil
+	return resp, nil
 }
 
 // Observe returns a channel that observes all leader proposal values as
@@ -142,20 +161,21 @@ func (e *Election) observe(ctx context.Context, ch chan<- v3.GetResponse) {
 	client := e.session.Client()
 
 	defer close(ch)
+	lastRev := int64(0)
 	for {
-		resp, err := client.Get(ctx, e.keyPrefix, v3.WithFirstCreate()...)
+		opts := append(v3.WithFirstCreate(), v3.WithRev(lastRev))
+		resp, err := client.Get(ctx, e.keyPrefix, opts...)
 		if err != nil {
 			return
 		}
 
 		var kv *mvccpb.KeyValue
 
-		cctx, cancel := context.WithCancel(ctx)
 		if len(resp.Kvs) == 0 {
+			cctx, cancel := context.WithCancel(ctx)
 			// wait for first key put on prefix
 			opts := []v3.OpOption{v3.WithRev(resp.Header.Revision), v3.WithPrefix()}
 			wch := client.Watch(cctx, e.keyPrefix, opts...)
-
 			for kv == nil {
 				wr, ok := <-wch
 				if !ok || wr.Err() != nil {
@@ -170,10 +190,12 @@ func (e *Election) observe(ctx context.Context, ch chan<- v3.GetResponse) {
 					}
 				}
 			}
+			cancel()
 		} else {
 			kv = resp.Kvs[0]
 		}
 
+		cctx, cancel := context.WithCancel(ctx)
 		wch := client.Watch(cctx, string(kv.Key), v3.WithRev(kv.ModRevision))
 		keyDeleted := false
 		for !keyDeleted {
@@ -183,6 +205,7 @@ func (e *Election) observe(ctx context.Context, ch chan<- v3.GetResponse) {
 			}
 			for _, ev := range wr.Events {
 				if ev.Type == mvccpb.DELETE {
+					lastRev = ev.Kv.ModRevision
 					keyDeleted = true
 					break
 				}
@@ -201,3 +224,9 @@ func (e *Election) observe(ctx context.Context, ch chan<- v3.GetResponse) {
 
 // Key returns the leader key if elected, empty string otherwise.
 func (e *Election) Key() string { return e.leaderKey }
+
+// Rev returns the leader key's creation revision, if elected.
+func (e *Election) Rev() int64 { return e.leaderRev }
+
+// Header is the response header from the last successful election proposal.
+func (m *Election) Header() *pb.ResponseHeader { return m.hdr }

embed/serve.go

@@ -25,6 +25,8 @@ import (
 
 	"github.com/coreos/etcd/etcdserver"
 	"github.com/coreos/etcd/etcdserver/api/v3client"
+	"github.com/coreos/etcd/etcdserver/api/v3election"
+	"github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb"
 	"github.com/coreos/etcd/etcdserver/api/v3lock"
 	"github.com/coreos/etcd/etcdserver/api/v3lock/v3lockpb"
 	"github.com/coreos/etcd/etcdserver/api/v3rpc"
@@ -66,10 +68,14 @@ func (sctx *serveCtx) serve(s *etcdserver.EtcdServer, tlscfg *tls.Config, handle
 	plog.Info("ready to serve client requests")
 
 	m := cmux.New(sctx.l)
+	v3c := v3client.New(s)
+	servElection := v3election.NewElectionServer(v3c)
+	servLock := v3lock.NewLockServer(v3c)
 
 	if sctx.insecure {
 		gs := v3rpc.Server(s, nil)
-		v3lockpb.RegisterLockServer(gs, v3lock.NewLockServer(v3client.New(s)))
+		v3electionpb.RegisterElectionServer(gs, servElection)
+		v3lockpb.RegisterLockServer(gs, servLock)
 		if sctx.serviceRegister != nil {
 			sctx.serviceRegister(gs)
 		}
@@ -97,7 +103,8 @@ func (sctx *serveCtx) serve(s *etcdserver.EtcdServer, tlscfg *tls.Config, handle
 
 	if sctx.secure {
 		gs := v3rpc.Server(s, tlscfg)
-		v3lockpb.RegisterLockServer(gs, v3lock.NewLockServer(v3client.New(s)))
+		v3electionpb.RegisterElectionServer(gs, servElection)
+		v3lockpb.RegisterLockServer(gs, servLock)
 		if sctx.serviceRegister != nil {
 			sctx.serviceRegister(gs)
 		}

etcdserver/api/v3election/doc.go

@@ -0,0 +1,16 @@
+// Copyright 2017 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 v3election provides a v3 election service from an etcdserver.
+package v3election

etcdserver/api/v3election/election.go

@@ -0,0 +1,123 @@
+// Copyright 2017 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 v3election
+
+import (
+	"golang.org/x/net/context"
+
+	"github.com/coreos/etcd/clientv3"
+	"github.com/coreos/etcd/clientv3/concurrency"
+	epb "github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb"
+)
+
+type electionServer struct {
+	c *clientv3.Client
+}
+
+func NewElectionServer(c *clientv3.Client) epb.ElectionServer {
+	return &electionServer{c}
+}
+
+func (es *electionServer) Campaign(ctx context.Context, req *epb.CampaignRequest) (*epb.CampaignResponse, error) {
+	s, err := es.session(ctx, req.Lease)
+	if err != nil {
+		return nil, err
+	}
+	e := concurrency.NewElection(s, string(req.Name))
+	if err = e.Campaign(ctx, string(req.Value)); err != nil {
+		return nil, err
+	}
+	return &epb.CampaignResponse{
+		Header: e.Header(),
+		Leader: &epb.LeaderKey{
+			Name:  req.Name,
+			Key:   []byte(e.Key()),
+			Rev:   e.Rev(),
+			Lease: int64(s.Lease()),
+		},
+	}, nil
+}
+
+func (es *electionServer) Proclaim(ctx context.Context, req *epb.ProclaimRequest) (*epb.ProclaimResponse, error) {
+	s, err := es.session(ctx, req.Leader.Lease)
+	if err != nil {
+		return nil, err
+	}
+	e := concurrency.ResumeElection(s, string(req.Leader.Name), string(req.Leader.Key), req.Leader.Rev)
+	if err := e.Proclaim(ctx, string(req.Value)); err != nil {
+		return nil, err
+	}
+	return &epb.ProclaimResponse{Header: e.Header()}, nil
+}
+
+func (es *electionServer) Observe(req *epb.LeaderRequest, stream epb.Election_ObserveServer) error {
+	s, err := es.session(stream.Context(), -1)
+	if err != nil {
+		return err
+	}
+	e := concurrency.NewElection(s, string(req.Name))
+	ch := e.Observe(stream.Context())
+	for stream.Context().Err() == nil {
+		select {
+		case <-stream.Context().Done():
+		case resp, ok := <-ch:
+			if !ok {
+				return nil
+			}
+			lresp := &epb.LeaderResponse{Header: resp.Header, Kv: resp.Kvs[0]}
+			if err := stream.Send(lresp); err != nil {
+				return err
+			}
+		}
+	}
+	return stream.Context().Err()
+}
+
+func (es *electionServer) Leader(ctx context.Context, req *epb.LeaderRequest) (*epb.LeaderResponse, error) {
+	s, err := es.session(ctx, -1)
+	if err != nil {
+		return nil, err
+	}
+	l, lerr := concurrency.NewElection(s, string(req.Name)).Leader(ctx)
+	if lerr != nil {
+		return nil, lerr
+	}
+	return &epb.LeaderResponse{Header: l.Header, Kv: l.Kvs[0]}, nil
+}
+
+func (es *electionServer) Resign(ctx context.Context, req *epb.ResignRequest) (*epb.ResignResponse, error) {
+	s, err := es.session(ctx, req.Leader.Lease)
+	if err != nil {
+		return nil, err
+	}
+	e := concurrency.ResumeElection(s, string(req.Leader.Name), string(req.Leader.Key), req.Leader.Rev)
+	if err := e.Resign(ctx); err != nil {
+		return nil, err
+	}
+	return &epb.ResignResponse{Header: e.Header()}, nil
+}
+
+func (es *electionServer) session(ctx context.Context, lease int64) (*concurrency.Session, error) {
+	s, err := concurrency.NewSession(
+		es.c,
+		concurrency.WithLease(clientv3.LeaseID(lease)),
+		concurrency.WithContext(ctx),
+	)
+	if err != nil {
+		return nil, err
+	}
+	s.Orphan()
+	return s, nil
+}

etcdserver/api/v3election/v3electionpb/v3election.pb.go

@@ -0,0 +1,2033 @@
+// Code generated by protoc-gen-gogo.
+// source: v3election.proto
+// DO NOT EDIT!
+
+/*
+	Package v3electionpb is a generated protocol buffer package.
+
+	It is generated from these files:
+		v3election.proto
+
+	It has these top-level messages:
+		CampaignRequest
+		CampaignResponse
+		LeaderKey
+		LeaderRequest
+		LeaderResponse
+		ResignRequest
+		ResignResponse
+		ProclaimRequest
+		ProclaimResponse
+*/
+package v3electionpb
+
+import (
+	"fmt"
+
+	proto "github.com/golang/protobuf/proto"
+
+	math "math"
+
+	etcdserverpb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+
+	mvccpb "github.com/coreos/etcd/mvcc/mvccpb"
+
+	context "golang.org/x/net/context"
+
+	grpc "google.golang.org/grpc"
+
+	io "io"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type CampaignRequest struct {
+	// name is the election's identifier for the campaign.
+	Name []byte `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	// lease is the ID of the lease attached to leadership of the election. If the
+	// lease expires or is revoked before resigning leadership, then the
+	// leadership is transferred to the next campaigner, if any.
+	Lease int64 `protobuf:"varint,2,opt,name=lease,proto3" json:"lease,omitempty"`
+	// value is the initial proclaimed value set when the campaigner wins the
+	// election.
+	Value []byte `protobuf:"bytes,3,opt,name=value,proto3" json:"value,omitempty"`
+}
+
+func (m *CampaignRequest) Reset()                    { *m = CampaignRequest{} }
+func (m *CampaignRequest) String() string            { return proto.CompactTextString(m) }
+func (*CampaignRequest) ProtoMessage()               {}
+func (*CampaignRequest) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{0} }
+
+type CampaignResponse struct {
+	Header *etcdserverpb.ResponseHeader `protobuf:"bytes,1,opt,name=header" json:"header,omitempty"`
+	// leader describes the resources used for holding leadereship of the election.
+	Leader *LeaderKey `protobuf:"bytes,2,opt,name=leader" json:"leader,omitempty"`
+}
+
+func (m *CampaignResponse) Reset()                    { *m = CampaignResponse{} }
+func (m *CampaignResponse) String() string            { return proto.CompactTextString(m) }
+func (*CampaignResponse) ProtoMessage()               {}
+func (*CampaignResponse) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{1} }
+
+func (m *CampaignResponse) GetHeader() *etcdserverpb.ResponseHeader {
+	if m != nil {
+		return m.Header
+	}
+	return nil
+}
+
+func (m *CampaignResponse) GetLeader() *LeaderKey {
+	if m != nil {
+		return m.Leader
+	}
+	return nil
+}
+
+type LeaderKey struct {
+	// name is the election identifier that correponds to the leadership key.
+	Name []byte `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	// key is an opaque key representing the ownership of the election. If the key
+	// is deleted, then leadership is lost.
+	Key []byte `protobuf:"bytes,2,opt,name=key,proto3" json:"key,omitempty"`
+	// rev is the creation revision of the key. It can be used to test for ownership
+	// of an election during transactions by testing the key's creation revision
+	// matches rev.
+	Rev int64 `protobuf:"varint,3,opt,name=rev,proto3" json:"rev,omitempty"`
+	// lease is the lease ID of the election leader.
+	Lease int64 `protobuf:"varint,4,opt,name=lease,proto3" json:"lease,omitempty"`
+}
+
+func (m *LeaderKey) Reset()                    { *m = LeaderKey{} }
+func (m *LeaderKey) String() string            { return proto.CompactTextString(m) }
+func (*LeaderKey) ProtoMessage()               {}
+func (*LeaderKey) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{2} }
+
+type LeaderRequest struct {
+	// name is the election identifier for the leadership information.
+	Name []byte `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+}
+
+func (m *LeaderRequest) Reset()                    { *m = LeaderRequest{} }
+func (m *LeaderRequest) String() string            { return proto.CompactTextString(m) }
+func (*LeaderRequest) ProtoMessage()               {}
+func (*LeaderRequest) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{3} }
+
+type LeaderResponse struct {
+	Header *etcdserverpb.ResponseHeader `protobuf:"bytes,1,opt,name=header" json:"header,omitempty"`
+	// kv is the key-value pair representing the latest leader update.
+	Kv *mvccpb.KeyValue `protobuf:"bytes,2,opt,name=kv" json:"kv,omitempty"`
+}
+
+func (m *LeaderResponse) Reset()                    { *m = LeaderResponse{} }
+func (m *LeaderResponse) String() string            { return proto.CompactTextString(m) }
+func (*LeaderResponse) ProtoMessage()               {}
+func (*LeaderResponse) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{4} }
+
+func (m *LeaderResponse) GetHeader() *etcdserverpb.ResponseHeader {
+	if m != nil {
+		return m.Header
+	}
+	return nil
+}
+
+func (m *LeaderResponse) GetKv() *mvccpb.KeyValue {
+	if m != nil {
+		return m.Kv
+	}
+	return nil
+}
+
+type ResignRequest struct {
+	// leader is the leadership to relinquish by resignation.
+	Leader *LeaderKey `protobuf:"bytes,1,opt,name=leader" json:"leader,omitempty"`
+}
+
+func (m *ResignRequest) Reset()                    { *m = ResignRequest{} }
+func (m *ResignRequest) String() string            { return proto.CompactTextString(m) }
+func (*ResignRequest) ProtoMessage()               {}
+func (*ResignRequest) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{5} }
+
+func (m *ResignRequest) GetLeader() *LeaderKey {
+	if m != nil {
+		return m.Leader
+	}
+	return nil
+}
+
+type ResignResponse struct {
+	Header *etcdserverpb.ResponseHeader `protobuf:"bytes,1,opt,name=header" json:"header,omitempty"`
+}
+
+func (m *ResignResponse) Reset()                    { *m = ResignResponse{} }
+func (m *ResignResponse) String() string            { return proto.CompactTextString(m) }
+func (*ResignResponse) ProtoMessage()               {}
+func (*ResignResponse) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{6} }
+
+func (m *ResignResponse) GetHeader() *etcdserverpb.ResponseHeader {
+	if m != nil {
+		return m.Header
+	}
+	return nil
+}
+
+type ProclaimRequest struct {
+	// leader is the leadership hold on the election.
+	Leader *LeaderKey `protobuf:"bytes,1,opt,name=leader" json:"leader,omitempty"`
+	// value is an update meant to overwrite the leader's current value.
+	Value []byte `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
+}
+
+func (m *ProclaimRequest) Reset()                    { *m = ProclaimRequest{} }
+func (m *ProclaimRequest) String() string            { return proto.CompactTextString(m) }
+func (*ProclaimRequest) ProtoMessage()               {}
+func (*ProclaimRequest) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{7} }
+
+func (m *ProclaimRequest) GetLeader() *LeaderKey {
+	if m != nil {
+		return m.Leader
+	}
+	return nil
+}
+
+type ProclaimResponse struct {
+	Header *etcdserverpb.ResponseHeader `protobuf:"bytes,1,opt,name=header" json:"header,omitempty"`
+}
+
+func (m *ProclaimResponse) Reset()                    { *m = ProclaimResponse{} }
+func (m *ProclaimResponse) String() string            { return proto.CompactTextString(m) }
+func (*ProclaimResponse) ProtoMessage()               {}
+func (*ProclaimResponse) Descriptor() ([]byte, []int) { return fileDescriptorV3Election, []int{8} }
+
+func (m *ProclaimResponse) GetHeader() *etcdserverpb.ResponseHeader {
+	if m != nil {
+		return m.Header
+	}
+	return nil
+}
+
+func init() {
+	proto.RegisterType((*CampaignRequest)(nil), "v3electionpb.CampaignRequest")
+	proto.RegisterType((*CampaignResponse)(nil), "v3electionpb.CampaignResponse")
+	proto.RegisterType((*LeaderKey)(nil), "v3electionpb.LeaderKey")
+	proto.RegisterType((*LeaderRequest)(nil), "v3electionpb.LeaderRequest")
+	proto.RegisterType((*LeaderResponse)(nil), "v3electionpb.LeaderResponse")
+	proto.RegisterType((*ResignRequest)(nil), "v3electionpb.ResignRequest")
+	proto.RegisterType((*ResignResponse)(nil), "v3electionpb.ResignResponse")
+	proto.RegisterType((*ProclaimRequest)(nil), "v3electionpb.ProclaimRequest")
+	proto.RegisterType((*ProclaimResponse)(nil), "v3electionpb.ProclaimResponse")
+}
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ context.Context
+var _ grpc.ClientConn
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+const _ = grpc.SupportPackageIsVersion4
+
+// Client API for Election service
+
+type ElectionClient interface {
+	// Campaign waits to acquire leadership in an election, returning a LeaderKey
+	// representing the leadership if successful. The LeaderKey can then be used
+	// to issue new values on the election, transactionally guard API requests on
+	// leadership still being held, and resign from the election.
+	Campaign(ctx context.Context, in *CampaignRequest, opts ...grpc.CallOption) (*CampaignResponse, error)
+	// Proclaim updates the leader's posted value with a new value.
+	Proclaim(ctx context.Context, in *ProclaimRequest, opts ...grpc.CallOption) (*ProclaimResponse, error)
+	// Leader returns the current election proclamation, if any.
+	Leader(ctx context.Context, in *LeaderRequest, opts ...grpc.CallOption) (*LeaderResponse, error)
+	// Observe streams election proclamations in-order as made by the election's
+	// elected leaders.
+	Observe(ctx context.Context, in *LeaderRequest, opts ...grpc.CallOption) (Election_ObserveClient, error)
+	// Resign releases election leadership so other campaigners may acquire
+	// leadership on the election.
+	Resign(ctx context.Context, in *ResignRequest, opts ...grpc.CallOption) (*ResignResponse, error)
+}
+
+type electionClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewElectionClient(cc *grpc.ClientConn) ElectionClient {
+	return &electionClient{cc}
+}
+
+func (c *electionClient) Campaign(ctx context.Context, in *CampaignRequest, opts ...grpc.CallOption) (*CampaignResponse, error) {
+	out := new(CampaignResponse)
+	err := grpc.Invoke(ctx, "/v3electionpb.Election/Campaign", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *electionClient) Proclaim(ctx context.Context, in *ProclaimRequest, opts ...grpc.CallOption) (*ProclaimResponse, error) {
+	out := new(ProclaimResponse)
+	err := grpc.Invoke(ctx, "/v3electionpb.Election/Proclaim", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *electionClient) Leader(ctx context.Context, in *LeaderRequest, opts ...grpc.CallOption) (*LeaderResponse, error) {
+	out := new(LeaderResponse)
+	err := grpc.Invoke(ctx, "/v3electionpb.Election/Leader", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *electionClient) Observe(ctx context.Context, in *LeaderRequest, opts ...grpc.CallOption) (Election_ObserveClient, error) {
+	stream, err := grpc.NewClientStream(ctx, &_Election_serviceDesc.Streams[0], c.cc, "/v3electionpb.Election/Observe", opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &electionObserveClient{stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+type Election_ObserveClient interface {
+	Recv() (*LeaderResponse, error)
+	grpc.ClientStream
+}
+
+type electionObserveClient struct {
+	grpc.ClientStream
+}
+
+func (x *electionObserveClient) Recv() (*LeaderResponse, error) {
+	m := new(LeaderResponse)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+func (c *electionClient) Resign(ctx context.Context, in *ResignRequest, opts ...grpc.CallOption) (*ResignResponse, error) {
+	out := new(ResignResponse)
+	err := grpc.Invoke(ctx, "/v3electionpb.Election/Resign", in, out, c.cc, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// Server API for Election service
+
+type ElectionServer interface {
+	// Campaign waits to acquire leadership in an election, returning a LeaderKey
+	// representing the leadership if successful. The LeaderKey can then be used
+	// to issue new values on the election, transactionally guard API requests on
+	// leadership still being held, and resign from the election.
+	Campaign(context.Context, *CampaignRequest) (*CampaignResponse, error)
+	// Proclaim updates the leader's posted value with a new value.
+	Proclaim(context.Context, *ProclaimRequest) (*ProclaimResponse, error)
+	// Leader returns the current election proclamation, if any.
+	Leader(context.Context, *LeaderRequest) (*LeaderResponse, error)
+	// Observe streams election proclamations in-order as made by the election's
+	// elected leaders.
+	Observe(*LeaderRequest, Election_ObserveServer) error
+	// Resign releases election leadership so other campaigners may acquire
+	// leadership on the election.
+	Resign(context.Context, *ResignRequest) (*ResignResponse, error)
+}
+
+func RegisterElectionServer(s *grpc.Server, srv ElectionServer) {
+	s.RegisterService(&_Election_serviceDesc, srv)
+}
+
+func _Election_Campaign_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(CampaignRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ElectionServer).Campaign(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/v3electionpb.Election/Campaign",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ElectionServer).Campaign(ctx, req.(*CampaignRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _Election_Proclaim_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ProclaimRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ElectionServer).Proclaim(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/v3electionpb.Election/Proclaim",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ElectionServer).Proclaim(ctx, req.(*ProclaimRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _Election_Leader_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(LeaderRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ElectionServer).Leader(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/v3electionpb.Election/Leader",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ElectionServer).Leader(ctx, req.(*LeaderRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _Election_Observe_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(LeaderRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(ElectionServer).Observe(m, &electionObserveServer{stream})
+}
+
+type Election_ObserveServer interface {
+	Send(*LeaderResponse) error
+	grpc.ServerStream
+}
+
+type electionObserveServer struct {
+	grpc.ServerStream
+}
+
+func (x *electionObserveServer) Send(m *LeaderResponse) error {
+	return x.ServerStream.SendMsg(m)
+}
+
+func _Election_Resign_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ResignRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ElectionServer).Resign(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/v3electionpb.Election/Resign",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ElectionServer).Resign(ctx, req.(*ResignRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _Election_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "v3electionpb.Election",
+	HandlerType: (*ElectionServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "Campaign",
+			Handler:    _Election_Campaign_Handler,
+		},
+		{
+			MethodName: "Proclaim",
+			Handler:    _Election_Proclaim_Handler,
+		},
+		{
+			MethodName: "Leader",
+			Handler:    _Election_Leader_Handler,
+		},
+		{
+			MethodName: "Resign",
+			Handler:    _Election_Resign_Handler,
+		},
+	},
+	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "Observe",
+			Handler:       _Election_Observe_Handler,
+			ServerStreams: true,
+		},
+	},
+	Metadata: "v3election.proto",
+}
+
+func (m *CampaignRequest) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *CampaignRequest) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if len(m.Name) > 0 {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Name)))
+		i += copy(dAtA[i:], m.Name)
+	}
+	if m.Lease != 0 {
+		dAtA[i] = 0x10
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Lease))
+	}
+	if len(m.Value) > 0 {
+		dAtA[i] = 0x1a
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Value)))
+		i += copy(dAtA[i:], m.Value)
+	}
+	return i, nil
+}
+
+func (m *CampaignResponse) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *CampaignResponse) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Header != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Header.Size()))
+		n1, err := m.Header.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n1
+	}
+	if m.Leader != nil {
+		dAtA[i] = 0x12
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Leader.Size()))
+		n2, err := m.Leader.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n2
+	}
+	return i, nil
+}
+
+func (m *LeaderKey) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *LeaderKey) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if len(m.Name) > 0 {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Name)))
+		i += copy(dAtA[i:], m.Name)
+	}
+	if len(m.Key) > 0 {
+		dAtA[i] = 0x12
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Key)))
+		i += copy(dAtA[i:], m.Key)
+	}
+	if m.Rev != 0 {
+		dAtA[i] = 0x18
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Rev))
+	}
+	if m.Lease != 0 {
+		dAtA[i] = 0x20
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Lease))
+	}
+	return i, nil
+}
+
+func (m *LeaderRequest) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *LeaderRequest) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if len(m.Name) > 0 {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Name)))
+		i += copy(dAtA[i:], m.Name)
+	}
+	return i, nil
+}
+
+func (m *LeaderResponse) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *LeaderResponse) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Header != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Header.Size()))
+		n3, err := m.Header.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n3
+	}
+	if m.Kv != nil {
+		dAtA[i] = 0x12
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Kv.Size()))
+		n4, err := m.Kv.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n4
+	}
+	return i, nil
+}
+
+func (m *ResignRequest) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *ResignRequest) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Leader != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Leader.Size()))
+		n5, err := m.Leader.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n5
+	}
+	return i, nil
+}
+
+func (m *ResignResponse) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *ResignResponse) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Header != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Header.Size()))
+		n6, err := m.Header.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n6
+	}
+	return i, nil
+}
+
+func (m *ProclaimRequest) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *ProclaimRequest) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Leader != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Leader.Size()))
+		n7, err := m.Leader.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n7
+	}
+	if len(m.Value) > 0 {
+		dAtA[i] = 0x12
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(len(m.Value)))
+		i += copy(dAtA[i:], m.Value)
+	}
+	return i, nil
+}
+
+func (m *ProclaimResponse) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalTo(dAtA)
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *ProclaimResponse) MarshalTo(dAtA []byte) (int, error) {
+	var i int
+	_ = i
+	var l int
+	_ = l
+	if m.Header != nil {
+		dAtA[i] = 0xa
+		i++
+		i = encodeVarintV3Election(dAtA, i, uint64(m.Header.Size()))
+		n8, err := m.Header.MarshalTo(dAtA[i:])
+		if err != nil {
+			return 0, err
+		}
+		i += n8
+	}
+	return i, nil
+}
+
+func encodeFixed64V3Election(dAtA []byte, offset int, v uint64) int {
+	dAtA[offset] = uint8(v)
+	dAtA[offset+1] = uint8(v >> 8)
+	dAtA[offset+2] = uint8(v >> 16)
+	dAtA[offset+3] = uint8(v >> 24)
+	dAtA[offset+4] = uint8(v >> 32)
+	dAtA[offset+5] = uint8(v >> 40)
+	dAtA[offset+6] = uint8(v >> 48)
+	dAtA[offset+7] = uint8(v >> 56)
+	return offset + 8
+}
+func encodeFixed32V3Election(dAtA []byte, offset int, v uint32) int {
+	dAtA[offset] = uint8(v)
+	dAtA[offset+1] = uint8(v >> 8)
+	dAtA[offset+2] = uint8(v >> 16)
+	dAtA[offset+3] = uint8(v >> 24)
+	return offset + 4
+}
+func encodeVarintV3Election(dAtA []byte, offset int, v uint64) int {
+	for v >= 1<<7 {
+		dAtA[offset] = uint8(v&0x7f | 0x80)
+		v >>= 7
+		offset++
+	}
+	dAtA[offset] = uint8(v)
+	return offset + 1
+}
+func (m *CampaignRequest) Size() (n int) {
+	var l int
+	_ = l
+	l = len(m.Name)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	if m.Lease != 0 {
+		n += 1 + sovV3Election(uint64(m.Lease))
+	}
+	l = len(m.Value)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *CampaignResponse) Size() (n int) {
+	var l int
+	_ = l
+	if m.Header != nil {
+		l = m.Header.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	if m.Leader != nil {
+		l = m.Leader.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *LeaderKey) Size() (n int) {
+	var l int
+	_ = l
+	l = len(m.Name)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	l = len(m.Key)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	if m.Rev != 0 {
+		n += 1 + sovV3Election(uint64(m.Rev))
+	}
+	if m.Lease != 0 {
+		n += 1 + sovV3Election(uint64(m.Lease))
+	}
+	return n
+}
+
+func (m *LeaderRequest) Size() (n int) {
+	var l int
+	_ = l
+	l = len(m.Name)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *LeaderResponse) Size() (n int) {
+	var l int
+	_ = l
+	if m.Header != nil {
+		l = m.Header.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	if m.Kv != nil {
+		l = m.Kv.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *ResignRequest) Size() (n int) {
+	var l int
+	_ = l
+	if m.Leader != nil {
+		l = m.Leader.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *ResignResponse) Size() (n int) {
+	var l int
+	_ = l
+	if m.Header != nil {
+		l = m.Header.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *ProclaimRequest) Size() (n int) {
+	var l int
+	_ = l
+	if m.Leader != nil {
+		l = m.Leader.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	l = len(m.Value)
+	if l > 0 {
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func (m *ProclaimResponse) Size() (n int) {
+	var l int
+	_ = l
+	if m.Header != nil {
+		l = m.Header.Size()
+		n += 1 + l + sovV3Election(uint64(l))
+	}
+	return n
+}
+
+func sovV3Election(x uint64) (n int) {
+	for {
+		n++
+		x >>= 7
+		if x == 0 {
+			break
+		}
+	}
+	return n
+}
+func sozV3Election(x uint64) (n int) {
+	return sovV3Election(uint64((x << 1) ^ uint64((int64(x) >> 63))))
+}
+func (m *CampaignRequest) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: CampaignRequest: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: CampaignRequest: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Name", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Name = append(m.Name[:0], dAtA[iNdEx:postIndex]...)
+			if m.Name == nil {
+				m.Name = []byte{}
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Lease", wireType)
+			}
+			m.Lease = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Lease |= (int64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 3:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Value", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Value = append(m.Value[:0], dAtA[iNdEx:postIndex]...)
+			if m.Value == nil {
+				m.Value = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *CampaignResponse) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: CampaignResponse: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: CampaignResponse: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Header", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Header == nil {
+				m.Header = &etcdserverpb.ResponseHeader{}
+			}
+			if err := m.Header.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Leader", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Leader == nil {
+				m.Leader = &LeaderKey{}
+			}
+			if err := m.Leader.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *LeaderKey) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: LeaderKey: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: LeaderKey: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Name", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Name = append(m.Name[:0], dAtA[iNdEx:postIndex]...)
+			if m.Name == nil {
+				m.Name = []byte{}
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Key", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Key = append(m.Key[:0], dAtA[iNdEx:postIndex]...)
+			if m.Key == nil {
+				m.Key = []byte{}
+			}
+			iNdEx = postIndex
+		case 3:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Rev", wireType)
+			}
+			m.Rev = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Rev |= (int64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 4:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Lease", wireType)
+			}
+			m.Lease = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Lease |= (int64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *LeaderRequest) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: LeaderRequest: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: LeaderRequest: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Name", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Name = append(m.Name[:0], dAtA[iNdEx:postIndex]...)
+			if m.Name == nil {
+				m.Name = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *LeaderResponse) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: LeaderResponse: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: LeaderResponse: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Header", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Header == nil {
+				m.Header = &etcdserverpb.ResponseHeader{}
+			}
+			if err := m.Header.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Kv", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Kv == nil {
+				m.Kv = &mvccpb.KeyValue{}
+			}
+			if err := m.Kv.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *ResignRequest) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: ResignRequest: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ResignRequest: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Leader", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Leader == nil {
+				m.Leader = &LeaderKey{}
+			}
+			if err := m.Leader.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *ResignResponse) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: ResignResponse: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ResignResponse: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Header", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Header == nil {
+				m.Header = &etcdserverpb.ResponseHeader{}
+			}
+			if err := m.Header.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *ProclaimRequest) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: ProclaimRequest: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ProclaimRequest: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Leader", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Leader == nil {
+				m.Leader = &LeaderKey{}
+			}
+			if err := m.Leader.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Value", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Value = append(m.Value[:0], dAtA[iNdEx:postIndex]...)
+			if m.Value == nil {
+				m.Value = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *ProclaimResponse) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: ProclaimResponse: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: ProclaimResponse: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Header", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Header == nil {
+				m.Header = &etcdserverpb.ResponseHeader{}
+			}
+			if err := m.Header.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipV3Election(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if skippy < 0 {
+				return ErrInvalidLengthV3Election
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func skipV3Election(dAtA []byte) (n int, err error) {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return 0, ErrIntOverflowV3Election
+			}
+			if iNdEx >= l {
+				return 0, io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		wireType := int(wire & 0x7)
+		switch wireType {
+		case 0:
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				iNdEx++
+				if dAtA[iNdEx-1] < 0x80 {
+					break
+				}
+			}
+			return iNdEx, nil
+		case 1:
+			iNdEx += 8
+			return iNdEx, nil
+		case 2:
+			var length int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowV3Election
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				length |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			iNdEx += length
+			if length < 0 {
+				return 0, ErrInvalidLengthV3Election
+			}
+			return iNdEx, nil
+		case 3:
+			for {
+				var innerWire uint64
+				var start int = iNdEx
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return 0, ErrIntOverflowV3Election
+					}
+					if iNdEx >= l {
+						return 0, io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					innerWire |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				innerWireType := int(innerWire & 0x7)
+				if innerWireType == 4 {
+					break
+				}
+				next, err := skipV3Election(dAtA[start:])
+				if err != nil {
+					return 0, err
+				}
+				iNdEx = start + next
+			}
+			return iNdEx, nil
+		case 4:
+			return iNdEx, nil
+		case 5:
+			iNdEx += 4
+			return iNdEx, nil
+		default:
+			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
+		}
+	}
+	panic("unreachable")
+}
+
+var (
+	ErrInvalidLengthV3Election = fmt.Errorf("proto: negative length found during unmarshaling")
+	ErrIntOverflowV3Election   = fmt.Errorf("proto: integer overflow")
+)
+
+func init() { proto.RegisterFile("v3election.proto", fileDescriptorV3Election) }
+
+var fileDescriptorV3Election = []byte{
+	// 540 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xa4, 0x54, 0xc1, 0x6e, 0xd3, 0x40,
+	0x10, 0x65, 0x9d, 0x10, 0xca, 0x90, 0xb6, 0x96, 0x55, 0x89, 0x34, 0xa4, 0x26, 0xda, 0x02, 0xaa,
+	0x72, 0xf0, 0xa2, 0x86, 0x53, 0x4e, 0x08, 0x04, 0xaa, 0x54, 0x24, 0xc0, 0x07, 0x04, 0xc7, 0x8d,
+	0x3b, 0x4a, 0xa2, 0x38, 0xde, 0xc5, 0x4e, 0x2d, 0xe5, 0xca, 0x2f, 0x70, 0xe1, 0x33, 0xf8, 0x0c,
+	0x8e, 0x48, 0xfc, 0x00, 0x0a, 0x7c, 0x08, 0xda, 0x5d, 0x1b, 0x3b, 0x6e, 0x88, 0x50, 0x73, 0xb1,
+	0xc6, 0x33, 0xcf, 0xf3, 0xe6, 0xbd, 0x9d, 0x35, 0xd8, 0x69, 0x1f, 0x43, 0x0c, 0xe6, 0x13, 0x11,
+	0x79, 0x32, 0x16, 0x73, 0xe1, 0x34, 0x8b, 0x8c, 0x1c, 0xb6, 0x0f, 0x46, 0x62, 0x24, 0x74, 0x81,
+	0xa9, 0xc8, 0x60, 0xda, 0x8f, 0x70, 0x1e, 0x5c, 0x30, 0xf5, 0x48, 0x30, 0x4e, 0x31, 0x2e, 0x85,
+	0x72, 0xc8, 0x62, 0x19, 0x64, 0xb8, 0x43, 0x8d, 0x9b, 0xa5, 0x41, 0xa0, 0x1f, 0x72, 0xc8, 0xa6,
+	0x69, 0x56, 0xea, 0x8c, 0x84, 0x18, 0x85, 0xc8, 0xb8, 0x9c, 0x30, 0x1e, 0x45, 0x62, 0xce, 0x15,
+	0x63, 0x62, 0xaa, 0xf4, 0x2d, 0xec, 0x3f, 0xe7, 0x33, 0xc9, 0x27, 0xa3, 0xc8, 0xc7, 0x8f, 0x97,
+	0x98, 0xcc, 0x1d, 0x07, 0xea, 0x11, 0x9f, 0x61, 0x8b, 0x74, 0xc9, 0x49, 0xd3, 0xd7, 0xb1, 0x73,
+	0x00, 0x37, 0x43, 0xe4, 0x09, 0xb6, 0xac, 0x2e, 0x39, 0xa9, 0xf9, 0xe6, 0x45, 0x65, 0x53, 0x1e,
+	0x5e, 0x62, 0xab, 0xa6, 0xa1, 0xe6, 0x85, 0x2e, 0xc0, 0x2e, 0x5a, 0x26, 0x52, 0x44, 0x09, 0x3a,
+	0x4f, 0xa0, 0x31, 0x46, 0x7e, 0x81, 0xb1, 0xee, 0x7a, 0xe7, 0xb4, 0xe3, 0x95, 0x85, 0x78, 0x39,
+	0xee, 0x4c, 0x63, 0xfc, 0x0c, 0xeb, 0x30, 0x68, 0x84, 0xe6, 0x2b, 0x4b, 0x7f, 0x75, 0xd7, 0x2b,
+	0x5b, 0xe6, 0xbd, 0xd2, 0xb5, 0x73, 0x5c, 0xf8, 0x19, 0x8c, 0x7e, 0x80, 0xdb, 0x7f, 0x93, 0x6b,
+	0x75, 0xd8, 0x50, 0x9b, 0xe2, 0x42, 0xb7, 0x6b, 0xfa, 0x2a, 0x54, 0x99, 0x18, 0x53, 0xad, 0xa0,
+	0xe6, 0xab, 0xb0, 0xd0, 0x5a, 0x2f, 0x69, 0xa5, 0xc7, 0xb0, 0x6b, 0x5a, 0x6f, 0xb0, 0x89, 0x8e,
+	0x61, 0x2f, 0x07, 0x6d, 0x25, 0xbc, 0x0b, 0xd6, 0x34, 0xcd, 0x44, 0xdb, 0x9e, 0x39, 0x51, 0xef,
+	0x1c, 0x17, 0xef, 0x94, 0xc1, 0xbe, 0x35, 0x4d, 0xe9, 0x53, 0xd8, 0xf5, 0x31, 0x29, 0x9d, 0x5a,
+	0xe1, 0x15, 0xf9, 0x3f, 0xaf, 0x5e, 0xc2, 0x5e, 0xde, 0x61, 0x9b, 0x59, 0xe9, 0x7b, 0xd8, 0x7f,
+	0x13, 0x8b, 0x20, 0xe4, 0x93, 0xd9, 0x75, 0x67, 0x29, 0x16, 0xc9, 0x2a, 0x2f, 0xd2, 0x19, 0xd8,
+	0x45, 0xe7, 0x6d, 0x66, 0x3c, 0xfd, 0x5a, 0x87, 0x9d, 0x17, 0xd9, 0x00, 0x8e, 0x84, 0x9d, 0x7c,
+	0x3f, 0x9d, 0xa3, 0xd5, 0xc9, 0x2a, 0x57, 0xa1, 0xed, 0xfe, 0xab, 0x6c, 0x58, 0xe8, 0xc3, 0x4f,
+	0x3f, 0x7e, 0x7f, 0xb6, 0xee, 0xd3, 0x36, 0x4b, 0xfb, 0x3c, 0x94, 0x63, 0xce, 0x72, 0x34, 0x0b,
+	0x32, 0xec, 0x80, 0xf4, 0x14, 0x63, 0x2e, 0xa4, 0xca, 0x58, 0xb1, 0xae, 0xca, 0x58, 0xd5, 0xbf,
+	0x89, 0x51, 0x66, 0x58, 0xc5, 0x38, 0x86, 0x86, 0x71, 0xd9, 0xb9, 0xb7, 0xce, 0xfb, 0x9c, 0xad,
+	0xb3, 0xbe, 0x98, 0x71, 0x1d, 0x6b, 0xae, 0x23, 0xda, 0xba, 0xca, 0x65, 0xce, 0x4d, 0x31, 0x85,
+	0x70, 0xeb, 0xf5, 0x50, 0xfb, 0xbf, 0x0d, 0xd5, 0x03, 0x4d, 0xe5, 0xd2, 0xc3, 0xab, 0x54, 0xc2,
+	0x74, 0x1f, 0x90, 0xde, 0x63, 0xa2, 0x74, 0x99, 0xa5, 0xad, 0x92, 0xad, 0x5c, 0x86, 0x2a, 0xd9,
+	0xea, 0x9e, 0x6f, 0xd2, 0x15, 0x6b, 0xe4, 0x80, 0xf4, 0x9e, 0xd9, 0xdf, 0x96, 0x2e, 0xf9, 0xbe,
+	0x74, 0xc9, 0xcf, 0xa5, 0x4b, 0xbe, 0xfc, 0x72, 0x6f, 0x0c, 0x1b, 0xfa, 0x8f, 0xd9, 0xff, 0x13,
+	0x00, 0x00, 0xff, 0xff, 0xfc, 0x4d, 0x5a, 0x40, 0xca, 0x05, 0x00, 0x00,
+}

etcdserver/api/v3election/v3electionpb/v3election.proto

@@ -0,0 +1,119 @@
+syntax = "proto3";
+package v3electionpb;
+
+import "gogoproto/gogo.proto";
+import "etcd/etcdserver/etcdserverpb/rpc.proto";
+import "etcd/mvcc/mvccpb/kv.proto";
+
+// for grpc-gateway
+import "google/api/annotations.proto";
+
+option (gogoproto.marshaler_all) = true;
+option (gogoproto.unmarshaler_all) = true;
+
+// The election service exposes client-side election facilities as a gRPC interface.
+service Election {
+  // Campaign waits to acquire leadership in an election, returning a LeaderKey
+  // representing the leadership if successful. The LeaderKey can then be used
+  // to issue new values on the election, transactionally guard API requests on
+  // leadership still being held, and resign from the election.
+  rpc Campaign(CampaignRequest) returns (CampaignResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/election/campaign"
+        body: "*"
+    };
+  }
+  // Proclaim updates the leader's posted value with a new value.
+  rpc Proclaim(ProclaimRequest) returns (ProclaimResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/election/proclaim"
+        body: "*"
+    };
+  }
+  // Leader returns the current election proclamation, if any.
+  rpc Leader(LeaderRequest) returns (LeaderResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/election/leader"
+        body: "*"
+    };
+  }
+  // Observe streams election proclamations in-order as made by the election's
+  // elected leaders.
+  rpc Observe(LeaderRequest) returns (stream LeaderResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/election/observe"
+        body: "*"
+    };
+  }
+  // Resign releases election leadership so other campaigners may acquire
+  // leadership on the election.
+  rpc Resign(ResignRequest) returns (ResignResponse) {
+      option (google.api.http) = {
+        post: "/v3alpha/election/resign"
+        body: "*"
+    };
+  }
+}
+
+message CampaignRequest {
+  // name is the election's identifier for the campaign.
+  bytes name = 1;
+  // lease is the ID of the lease attached to leadership of the election. If the
+  // lease expires or is revoked before resigning leadership, then the
+  // leadership is transferred to the next campaigner, if any.
+  int64 lease = 2;
+  // value is the initial proclaimed value set when the campaigner wins the
+  // election.
+  bytes value = 3;
+}
+
+message CampaignResponse {
+  etcdserverpb.ResponseHeader header = 1;
+  // leader describes the resources used for holding leadereship of the election.
+  LeaderKey leader = 2;
+}
+
+message LeaderKey {
+  // name is the election identifier that correponds to the leadership key.
+  bytes name = 1;
+  // key is an opaque key representing the ownership of the election. If the key
+  // is deleted, then leadership is lost.
+  bytes key = 2;
+  // rev is the creation revision of the key. It can be used to test for ownership
+  // of an election during transactions by testing the key's creation revision
+  // matches rev.
+  int64 rev = 3;
+  // lease is the lease ID of the election leader.
+  int64 lease = 4;
+}
+
+message LeaderRequest {
+  // name is the election identifier for the leadership information.
+  bytes name = 1;
+}
+
+message LeaderResponse {
+  etcdserverpb.ResponseHeader header = 1;
+  // kv is the key-value pair representing the latest leader update.
+  mvccpb.KeyValue kv = 2;
+}
+
+message ResignRequest {
+  // leader is the leadership to relinquish by resignation.
+  LeaderKey leader = 1;
+}
+
+message ResignResponse {
+  etcdserverpb.ResponseHeader header = 1;
+}
+
+message ProclaimRequest {
+  // leader is the leadership hold on the election.
+  LeaderKey leader = 1;
+  // value is an update meant to overwrite the leader's current value.
+  bytes value = 2;
+}
+
+message ProclaimResponse {
+  etcdserverpb.ResponseHeader header = 1;
+}

etcdserver/api/v3rpc/watch.go

@@ -171,6 +171,11 @@ func (sws *serverWatchStream) recvLoop() error {
 				// \x00 is the smallest key
 				creq.Key = []byte{0}
 			}
+			if len(creq.RangeEnd) == 0 {
+				// force nil since watchstream.Watch distinguishes
+				// between nil and []byte{} for single key / >=
+				creq.RangeEnd = nil
+			}
 			if len(creq.RangeEnd) == 1 && creq.RangeEnd[0] == 0 {
 				// support  >= key queries
 				creq.RangeEnd = []byte{}

integration/cluster.go

@@ -39,6 +39,8 @@ import (
 	"github.com/coreos/etcd/etcdserver"
 	"github.com/coreos/etcd/etcdserver/api/v2http"
 	"github.com/coreos/etcd/etcdserver/api/v3client"
+	"github.com/coreos/etcd/etcdserver/api/v3election"
+	epb "github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb"
 	"github.com/coreos/etcd/etcdserver/api/v3lock"
 	lockpb "github.com/coreos/etcd/etcdserver/api/v3lock/v3lockpb"
 	"github.com/coreos/etcd/etcdserver/api/v3rpc"
@@ -668,6 +670,7 @@ func (m *member) Launch() error {
 		m.grpcServer = v3rpc.Server(m.s, tlscfg)
 		m.serverClient = v3client.New(m.s)
 		lockpb.RegisterLockServer(m.grpcServer, v3lock.NewLockServer(m.serverClient))
+		epb.RegisterElectionServer(m.grpcServer, v3election.NewElectionServer(m.serverClient))
 		go m.grpcServer.Serve(m.grpcListener)
 	}
 

integration/v3election_grpc_test.go

@@ -0,0 +1,173 @@
+// Copyright 2017 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 integration
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	epb "github.com/coreos/etcd/etcdserver/api/v3election/v3electionpb"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"github.com/coreos/etcd/pkg/testutil"
+	"golang.org/x/net/context"
+)
+
+// TestV3ElectionCampaign checks that Campaign will not give
+// simultaneous leadership to multiple campaigners.
+func TestV3ElectionCampaign(t *testing.T) {
+	defer testutil.AfterTest(t)
+	clus := NewClusterV3(t, &ClusterConfig{Size: 1})
+	defer clus.Terminate(t)
+
+	lease1, err1 := toGRPC(clus.RandClient()).Lease.LeaseGrant(context.TODO(), &pb.LeaseGrantRequest{TTL: 30})
+	if err1 != nil {
+		t.Fatal(err1)
+	}
+	lease2, err2 := toGRPC(clus.RandClient()).Lease.LeaseGrant(context.TODO(), &pb.LeaseGrantRequest{TTL: 30})
+	if err2 != nil {
+		t.Fatal(err2)
+	}
+
+	lc := epb.NewElectionClient(clus.Client(0).ActiveConnection())
+	req1 := &epb.CampaignRequest{Name: []byte("foo"), Lease: lease1.ID, Value: []byte("abc")}
+	l1, lerr1 := lc.Campaign(context.TODO(), req1)
+	if lerr1 != nil {
+		t.Fatal(lerr1)
+	}
+
+	campaignc := make(chan struct{})
+	go func() {
+		defer close(campaignc)
+		req2 := &epb.CampaignRequest{Name: []byte("foo"), Lease: lease2.ID, Value: []byte("def")}
+		l2, lerr2 := lc.Campaign(context.TODO(), req2)
+		if lerr2 != nil {
+			t.Fatal(lerr2)
+		}
+		if l1.Header.Revision >= l2.Header.Revision {
+			t.Fatalf("expected l1 revision < l2 revision, got %d >= %d", l1.Header.Revision, l2.Header.Revision)
+		}
+	}()
+
+	select {
+	case <-time.After(200 * time.Millisecond):
+	case <-campaignc:
+		t.Fatalf("got leadership before resign")
+	}
+
+	if _, uerr := lc.Resign(context.TODO(), &epb.ResignRequest{Leader: l1.Leader}); uerr != nil {
+		t.Fatal(uerr)
+	}
+
+	select {
+	case <-time.After(200 * time.Millisecond):
+		t.Fatalf("campaigner unelected after resign")
+	case <-campaignc:
+	}
+
+	lval, lverr := lc.Leader(context.TODO(), &epb.LeaderRequest{Name: []byte("foo")})
+	if lverr != nil {
+		t.Fatal(lverr)
+	}
+
+	if string(lval.Kv.Value) != "def" {
+		t.Fatalf("got election value %q, expected %q", string(lval.Kv.Value), "def")
+	}
+}
+
+// TestV3ElectionObserve checks that an Observe stream receives
+// proclamations from different leaders uninterrupted.
+func TestV3ElectionObserve(t *testing.T) {
+	defer testutil.AfterTest(t)
+	clus := NewClusterV3(t, &ClusterConfig{Size: 1})
+	defer clus.Terminate(t)
+
+	lc := epb.NewElectionClient(clus.Client(0).ActiveConnection())
+
+	// observe 10 leadership events
+	observec := make(chan struct{})
+	go func() {
+		defer close(observec)
+		s, err := lc.Observe(context.Background(), &epb.LeaderRequest{Name: []byte("foo")})
+		observec <- struct{}{}
+		if err != nil {
+			t.Fatal(err)
+		}
+		for i := 0; i < 10; i++ {
+			resp, rerr := s.Recv()
+			if rerr != nil {
+				t.Fatal(rerr)
+			}
+			if string(resp.Kv.Value) != fmt.Sprintf("%d", i) {
+				t.Fatalf(`got observe value %q, expected "%d"`, string(resp.Kv.Value), i)
+			}
+		}
+	}()
+
+	select {
+	case <-observec:
+	case <-time.After(time.Second):
+		t.Fatalf("observe stream took too long to start")
+	}
+
+	lease1, err1 := toGRPC(clus.RandClient()).Lease.LeaseGrant(context.TODO(), &pb.LeaseGrantRequest{TTL: 30})
+	if err1 != nil {
+		t.Fatal(err1)
+	}
+	c1, cerr1 := lc.Campaign(context.TODO(), &epb.CampaignRequest{Name: []byte("foo"), Lease: lease1.ID, Value: []byte("0")})
+	if cerr1 != nil {
+		t.Fatal(cerr1)
+	}
+
+	// overlap other leader so it waits on resign
+	leader2c := make(chan struct{})
+	go func() {
+		defer close(leader2c)
+
+		lease2, err2 := toGRPC(clus.RandClient()).Lease.LeaseGrant(context.TODO(), &pb.LeaseGrantRequest{TTL: 30})
+		if err2 != nil {
+			t.Fatal(err2)
+		}
+		c2, cerr2 := lc.Campaign(context.TODO(), &epb.CampaignRequest{Name: []byte("foo"), Lease: lease2.ID, Value: []byte("5")})
+		if cerr2 != nil {
+			t.Fatal(cerr2)
+		}
+		for i := 6; i < 10; i++ {
+			v := []byte(fmt.Sprintf("%d", i))
+			req := &epb.ProclaimRequest{Leader: c2.Leader, Value: v}
+			if _, err := lc.Proclaim(context.TODO(), req); err != nil {
+				t.Fatal(err)
+			}
+		}
+	}()
+
+	for i := 1; i < 5; i++ {
+		v := []byte(fmt.Sprintf("%d", i))
+		req := &epb.ProclaimRequest{Leader: c1.Leader, Value: v}
+		if _, err := lc.Proclaim(context.TODO(), req); err != nil {
+			t.Fatal(err)
+		}
+	}
+	// start second leader
+	lc.Resign(context.TODO(), &epb.ResignRequest{Leader: c1.Leader})
+
+	select {
+	case <-observec:
+	case <-time.After(time.Second):
+		t.Fatalf("observe did not observe all events in time")
+	}
+
+	<-leader2c
+}

scripts/genproto.sh

@@ -17,7 +17,7 @@ if ! [[ $(protoc --version) =~ "3.2.0" ]]; then
 fi
 
 # directories containing protos to be built
-DIRS="./wal/walpb ./etcdserver/etcdserverpb ./snap/snappb ./raft/raftpb ./mvcc/mvccpb ./lease/leasepb ./auth/authpb ./etcdserver/api/v3lock/v3lockpb"
+DIRS="./wal/walpb ./etcdserver/etcdserverpb ./snap/snappb ./raft/raftpb ./mvcc/mvccpb ./lease/leasepb ./auth/authpb ./etcdserver/api/v3lock/v3lockpb ./etcdserver/api/v3election/v3electionpb"
 
 # exact version of protoc-gen-gogo to build
 GOGO_PROTO_SHA="8d70fb3182befc465c4a1eac8ad4d38ff49778e2"

tools/functional-tester/etcd-runner/command/election_command.go

@@ -94,7 +94,7 @@ func runElectionFunc(cmd *cobra.Command, args []string) {
 			}
 		}
 		rcs[i].validate = func() error {
-			if l, err := e.Leader(context.TODO()); err == nil && l != observedLeader {
+			if l, err := e.Leader(context.TODO()); err == nil && string(l.Kvs[0].Value) != observedLeader {
 				return fmt.Errorf("expected leader %q, got %q", observedLeader, l)
 			}
 			validatec <- struct{}{}