Update libkv dependency

vendor/github.com/coreos/etcd/clientv3/auth.go

@@ -0,0 +1,222 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/coreos/etcd/auth/authpb"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type (
+	AuthEnableResponse               pb.AuthEnableResponse
+	AuthDisableResponse              pb.AuthDisableResponse
+	AuthenticateResponse             pb.AuthenticateResponse
+	AuthUserAddResponse              pb.AuthUserAddResponse
+	AuthUserDeleteResponse           pb.AuthUserDeleteResponse
+	AuthUserChangePasswordResponse   pb.AuthUserChangePasswordResponse
+	AuthUserGrantRoleResponse        pb.AuthUserGrantRoleResponse
+	AuthUserGetResponse              pb.AuthUserGetResponse
+	AuthUserRevokeRoleResponse       pb.AuthUserRevokeRoleResponse
+	AuthRoleAddResponse              pb.AuthRoleAddResponse
+	AuthRoleGrantPermissionResponse  pb.AuthRoleGrantPermissionResponse
+	AuthRoleGetResponse              pb.AuthRoleGetResponse
+	AuthRoleRevokePermissionResponse pb.AuthRoleRevokePermissionResponse
+	AuthRoleDeleteResponse           pb.AuthRoleDeleteResponse
+	AuthUserListResponse             pb.AuthUserListResponse
+	AuthRoleListResponse             pb.AuthRoleListResponse
+
+	PermissionType authpb.Permission_Type
+	Permission     authpb.Permission
+)
+
+const (
+	PermRead      = authpb.READ
+	PermWrite     = authpb.WRITE
+	PermReadWrite = authpb.READWRITE
+)
+
+type Auth interface {
+	// AuthEnable enables auth of an etcd cluster.
+	AuthEnable(ctx context.Context) (*AuthEnableResponse, error)
+
+	// AuthDisable disables auth of an etcd cluster.
+	AuthDisable(ctx context.Context) (*AuthDisableResponse, error)
+
+	// UserAdd adds a new user to an etcd cluster.
+	UserAdd(ctx context.Context, name string, password string) (*AuthUserAddResponse, error)
+
+	// UserDelete deletes a user from an etcd cluster.
+	UserDelete(ctx context.Context, name string) (*AuthUserDeleteResponse, error)
+
+	// UserChangePassword changes a password of a user.
+	UserChangePassword(ctx context.Context, name string, password string) (*AuthUserChangePasswordResponse, error)
+
+	// UserGrantRole grants a role to a user.
+	UserGrantRole(ctx context.Context, user string, role string) (*AuthUserGrantRoleResponse, error)
+
+	// UserGet gets a detailed information of a user.
+	UserGet(ctx context.Context, name string) (*AuthUserGetResponse, error)
+
+	// UserList gets a list of all users.
+	UserList(ctx context.Context) (*AuthUserListResponse, error)
+
+	// UserRevokeRole revokes a role of a user.
+	UserRevokeRole(ctx context.Context, name string, role string) (*AuthUserRevokeRoleResponse, error)
+
+	// RoleAdd adds a new role to an etcd cluster.
+	RoleAdd(ctx context.Context, name string) (*AuthRoleAddResponse, error)
+
+	// RoleGrantPermission grants a permission to a role.
+	RoleGrantPermission(ctx context.Context, name string, key, rangeEnd string, permType PermissionType) (*AuthRoleGrantPermissionResponse, error)
+
+	// RoleGet gets a detailed information of a role.
+	RoleGet(ctx context.Context, role string) (*AuthRoleGetResponse, error)
+
+	// RoleList gets a list of all roles.
+	RoleList(ctx context.Context) (*AuthRoleListResponse, error)
+
+	// RoleRevokePermission revokes a permission from a role.
+	RoleRevokePermission(ctx context.Context, role string, key, rangeEnd string) (*AuthRoleRevokePermissionResponse, error)
+
+	// RoleDelete deletes a role.
+	RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error)
+}
+
+type auth struct {
+	remote pb.AuthClient
+}
+
+func NewAuth(c *Client) Auth {
+	return &auth{remote: pb.NewAuthClient(c.ActiveConnection())}
+}
+
+func (auth *auth) AuthEnable(ctx context.Context) (*AuthEnableResponse, error) {
+	resp, err := auth.remote.AuthEnable(ctx, &pb.AuthEnableRequest{}, grpc.FailFast(false))
+	return (*AuthEnableResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) AuthDisable(ctx context.Context) (*AuthDisableResponse, error) {
+	resp, err := auth.remote.AuthDisable(ctx, &pb.AuthDisableRequest{}, grpc.FailFast(false))
+	return (*AuthDisableResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserAdd(ctx context.Context, name string, password string) (*AuthUserAddResponse, error) {
+	resp, err := auth.remote.UserAdd(ctx, &pb.AuthUserAddRequest{Name: name, Password: password})
+	return (*AuthUserAddResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserDelete(ctx context.Context, name string) (*AuthUserDeleteResponse, error) {
+	resp, err := auth.remote.UserDelete(ctx, &pb.AuthUserDeleteRequest{Name: name})
+	return (*AuthUserDeleteResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserChangePassword(ctx context.Context, name string, password string) (*AuthUserChangePasswordResponse, error) {
+	resp, err := auth.remote.UserChangePassword(ctx, &pb.AuthUserChangePasswordRequest{Name: name, Password: password})
+	return (*AuthUserChangePasswordResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserGrantRole(ctx context.Context, user string, role string) (*AuthUserGrantRoleResponse, error) {
+	resp, err := auth.remote.UserGrantRole(ctx, &pb.AuthUserGrantRoleRequest{User: user, Role: role})
+	return (*AuthUserGrantRoleResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserGet(ctx context.Context, name string) (*AuthUserGetResponse, error) {
+	resp, err := auth.remote.UserGet(ctx, &pb.AuthUserGetRequest{Name: name}, grpc.FailFast(false))
+	return (*AuthUserGetResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserList(ctx context.Context) (*AuthUserListResponse, error) {
+	resp, err := auth.remote.UserList(ctx, &pb.AuthUserListRequest{}, grpc.FailFast(false))
+	return (*AuthUserListResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) UserRevokeRole(ctx context.Context, name string, role string) (*AuthUserRevokeRoleResponse, error) {
+	resp, err := auth.remote.UserRevokeRole(ctx, &pb.AuthUserRevokeRoleRequest{Name: name, Role: role})
+	return (*AuthUserRevokeRoleResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleAdd(ctx context.Context, name string) (*AuthRoleAddResponse, error) {
+	resp, err := auth.remote.RoleAdd(ctx, &pb.AuthRoleAddRequest{Name: name})
+	return (*AuthRoleAddResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleGrantPermission(ctx context.Context, name string, key, rangeEnd string, permType PermissionType) (*AuthRoleGrantPermissionResponse, error) {
+	perm := &authpb.Permission{
+		Key:      []byte(key),
+		RangeEnd: []byte(rangeEnd),
+		PermType: authpb.Permission_Type(permType),
+	}
+	resp, err := auth.remote.RoleGrantPermission(ctx, &pb.AuthRoleGrantPermissionRequest{Name: name, Perm: perm})
+	return (*AuthRoleGrantPermissionResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleGet(ctx context.Context, role string) (*AuthRoleGetResponse, error) {
+	resp, err := auth.remote.RoleGet(ctx, &pb.AuthRoleGetRequest{Role: role}, grpc.FailFast(false))
+	return (*AuthRoleGetResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleList(ctx context.Context) (*AuthRoleListResponse, error) {
+	resp, err := auth.remote.RoleList(ctx, &pb.AuthRoleListRequest{}, grpc.FailFast(false))
+	return (*AuthRoleListResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleRevokePermission(ctx context.Context, role string, key, rangeEnd string) (*AuthRoleRevokePermissionResponse, error) {
+	resp, err := auth.remote.RoleRevokePermission(ctx, &pb.AuthRoleRevokePermissionRequest{Role: role, Key: key, RangeEnd: rangeEnd})
+	return (*AuthRoleRevokePermissionResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *auth) RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error) {
+	resp, err := auth.remote.RoleDelete(ctx, &pb.AuthRoleDeleteRequest{Role: role})
+	return (*AuthRoleDeleteResponse)(resp), toErr(ctx, err)
+}
+
+func StrToPermissionType(s string) (PermissionType, error) {
+	val, ok := authpb.Permission_Type_value[strings.ToUpper(s)]
+	if ok {
+		return PermissionType(val), nil
+	}
+	return PermissionType(-1), fmt.Errorf("invalid permission type: %s", s)
+}
+
+type authenticator struct {
+	conn   *grpc.ClientConn // conn in-use
+	remote pb.AuthClient
+}
+
+func (auth *authenticator) authenticate(ctx context.Context, name string, password string) (*AuthenticateResponse, error) {
+	resp, err := auth.remote.Authenticate(ctx, &pb.AuthenticateRequest{Name: name, Password: password}, grpc.FailFast(false))
+	return (*AuthenticateResponse)(resp), toErr(ctx, err)
+}
+
+func (auth *authenticator) close() {
+	auth.conn.Close()
+}
+
+func newAuthenticator(endpoint string, opts []grpc.DialOption) (*authenticator, error) {
+	conn, err := grpc.Dial(endpoint, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &authenticator{
+		conn:   conn,
+		remote: pb.NewAuthClient(conn),
+	}, nil
+}

vendor/github.com/coreos/etcd/clientv3/balancer.go

@@ -0,0 +1,356 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"net/url"
+	"strings"
+	"sync"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+// ErrNoAddrAvilable is returned by Get() when the balancer does not have
+// any active connection to endpoints at the time.
+// This error is returned only when opts.BlockingWait is true.
+var ErrNoAddrAvilable = grpc.Errorf(codes.Unavailable, "there is no address available")
+
+// simpleBalancer does the bare minimum to expose multiple eps
+// to the grpc reconnection code path
+type simpleBalancer struct {
+	// addrs are the client's endpoints for grpc
+	addrs []grpc.Address
+	// notifyCh notifies grpc of the set of addresses for connecting
+	notifyCh chan []grpc.Address
+
+	// readyc closes once the first connection is up
+	readyc    chan struct{}
+	readyOnce sync.Once
+
+	// mu protects upEps, pinAddr, and connectingAddr
+	mu sync.RWMutex
+
+	// upc closes when upEps transitions from empty to non-zero or the balancer closes.
+	upc chan struct{}
+
+	// downc closes when grpc calls down() on pinAddr
+	downc chan struct{}
+
+	// stopc is closed to signal updateNotifyLoop should stop.
+	stopc chan struct{}
+
+	// donec closes when all goroutines are exited
+	donec chan struct{}
+
+	// updateAddrsC notifies updateNotifyLoop to update addrs.
+	updateAddrsC chan struct{}
+
+	// grpc issues TLS cert checks using the string passed into dial so
+	// that string must be the host. To recover the full scheme://host URL,
+	// have a map from hosts to the original endpoint.
+	host2ep map[string]string
+
+	// pinAddr is the currently pinned address; set to the empty string on
+	// intialization and shutdown.
+	pinAddr string
+
+	closed bool
+}
+
+func newSimpleBalancer(eps []string) *simpleBalancer {
+	notifyCh := make(chan []grpc.Address, 1)
+	addrs := make([]grpc.Address, len(eps))
+	for i := range eps {
+		addrs[i].Addr = getHost(eps[i])
+	}
+	sb := &simpleBalancer{
+		addrs:        addrs,
+		notifyCh:     notifyCh,
+		readyc:       make(chan struct{}),
+		upc:          make(chan struct{}),
+		stopc:        make(chan struct{}),
+		downc:        make(chan struct{}),
+		donec:        make(chan struct{}),
+		updateAddrsC: make(chan struct{}, 1),
+		host2ep:      getHost2ep(eps),
+	}
+	close(sb.downc)
+	go sb.updateNotifyLoop()
+	return sb
+}
+
+func (b *simpleBalancer) Start(target string, config grpc.BalancerConfig) error { return nil }
+
+func (b *simpleBalancer) ConnectNotify() <-chan struct{} {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.upc
+}
+
+func (b *simpleBalancer) getEndpoint(host string) string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.host2ep[host]
+}
+
+func getHost2ep(eps []string) map[string]string {
+	hm := make(map[string]string, len(eps))
+	for i := range eps {
+		_, host, _ := parseEndpoint(eps[i])
+		hm[host] = eps[i]
+	}
+	return hm
+}
+
+func (b *simpleBalancer) updateAddrs(eps []string) {
+	np := getHost2ep(eps)
+
+	b.mu.Lock()
+
+	match := len(np) == len(b.host2ep)
+	for k, v := range np {
+		if b.host2ep[k] != v {
+			match = false
+			break
+		}
+	}
+	if match {
+		// same endpoints, so no need to update address
+		b.mu.Unlock()
+		return
+	}
+
+	b.host2ep = np
+
+	addrs := make([]grpc.Address, 0, len(eps))
+	for i := range eps {
+		addrs = append(addrs, grpc.Address{Addr: getHost(eps[i])})
+	}
+	b.addrs = addrs
+
+	// updating notifyCh can trigger new connections,
+	// only update addrs if all connections are down
+	// or addrs does not include pinAddr.
+	update := !hasAddr(addrs, b.pinAddr)
+	b.mu.Unlock()
+
+	if update {
+		select {
+		case b.updateAddrsC <- struct{}{}:
+		case <-b.stopc:
+		}
+	}
+}
+
+func hasAddr(addrs []grpc.Address, targetAddr string) bool {
+	for _, addr := range addrs {
+		if targetAddr == addr.Addr {
+			return true
+		}
+	}
+	return false
+}
+
+func (b *simpleBalancer) updateNotifyLoop() {
+	defer close(b.donec)
+
+	for {
+		b.mu.RLock()
+		upc, downc, addr := b.upc, b.downc, b.pinAddr
+		b.mu.RUnlock()
+		// downc or upc should be closed
+		select {
+		case <-downc:
+			downc = nil
+		default:
+		}
+		select {
+		case <-upc:
+			upc = nil
+		default:
+		}
+		switch {
+		case downc == nil && upc == nil:
+			// stale
+			select {
+			case <-b.stopc:
+				return
+			default:
+			}
+		case downc == nil:
+			b.notifyAddrs()
+			select {
+			case <-upc:
+			case <-b.updateAddrsC:
+				b.notifyAddrs()
+			case <-b.stopc:
+				return
+			}
+		case upc == nil:
+			select {
+			// close connections that are not the pinned address
+			case b.notifyCh <- []grpc.Address{{Addr: addr}}:
+			case <-downc:
+			case <-b.stopc:
+				return
+			}
+			select {
+			case <-downc:
+			case <-b.updateAddrsC:
+			case <-b.stopc:
+				return
+			}
+			b.notifyAddrs()
+		}
+	}
+}
+
+func (b *simpleBalancer) notifyAddrs() {
+	b.mu.RLock()
+	addrs := b.addrs
+	b.mu.RUnlock()
+	select {
+	case b.notifyCh <- addrs:
+	case <-b.stopc:
+	}
+}
+
+func (b *simpleBalancer) Up(addr grpc.Address) func(error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	// gRPC might call Up after it called Close. We add this check
+	// to "fix" it up at application layer. Or our simplerBalancer
+	// might panic since b.upc is closed.
+	if b.closed {
+		return func(err error) {}
+	}
+	// gRPC might call Up on a stale address.
+	// Prevent updating pinAddr with a stale address.
+	if !hasAddr(b.addrs, addr.Addr) {
+		return func(err error) {}
+	}
+	if b.pinAddr != "" {
+		return func(err error) {}
+	}
+	// notify waiting Get()s and pin first connected address
+	close(b.upc)
+	b.downc = make(chan struct{})
+	b.pinAddr = addr.Addr
+	// notify client that a connection is up
+	b.readyOnce.Do(func() { close(b.readyc) })
+	return func(err error) {
+		b.mu.Lock()
+		b.upc = make(chan struct{})
+		close(b.downc)
+		b.pinAddr = ""
+		b.mu.Unlock()
+	}
+}
+
+func (b *simpleBalancer) Get(ctx context.Context, opts grpc.BalancerGetOptions) (grpc.Address, func(), error) {
+	var (
+		addr   string
+		closed bool
+	)
+
+	// If opts.BlockingWait is false (for fail-fast RPCs), it should return
+	// an address it has notified via Notify immediately instead of blocking.
+	if !opts.BlockingWait {
+		b.mu.RLock()
+		closed = b.closed
+		addr = b.pinAddr
+		b.mu.RUnlock()
+		if closed {
+			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
+		}
+		if addr == "" {
+			return grpc.Address{Addr: ""}, nil, ErrNoAddrAvilable
+		}
+		return grpc.Address{Addr: addr}, func() {}, nil
+	}
+
+	for {
+		b.mu.RLock()
+		ch := b.upc
+		b.mu.RUnlock()
+		select {
+		case <-ch:
+		case <-b.donec:
+			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
+		case <-ctx.Done():
+			return grpc.Address{Addr: ""}, nil, ctx.Err()
+		}
+		b.mu.RLock()
+		closed = b.closed
+		addr = b.pinAddr
+		b.mu.RUnlock()
+		// Close() which sets b.closed = true can be called before Get(), Get() must exit if balancer is closed.
+		if closed {
+			return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
+		}
+		if addr != "" {
+			break
+		}
+	}
+	return grpc.Address{Addr: addr}, func() {}, nil
+}
+
+func (b *simpleBalancer) Notify() <-chan []grpc.Address { return b.notifyCh }
+
+func (b *simpleBalancer) Close() error {
+	b.mu.Lock()
+	// In case gRPC calls close twice. TODO: remove the checking
+	// when we are sure that gRPC wont call close twice.
+	if b.closed {
+		b.mu.Unlock()
+		<-b.donec
+		return nil
+	}
+	b.closed = true
+	close(b.stopc)
+	b.pinAddr = ""
+
+	// In the case of following scenario:
+	//	1. upc is not closed; no pinned address
+	// 	2. client issues an rpc, calling invoke(), which calls Get(), enters for loop, blocks
+	// 	3. clientconn.Close() calls balancer.Close(); closed = true
+	// 	4. for loop in Get() never exits since ctx is the context passed in by the client and may not be canceled
+	// we must close upc so Get() exits from blocking on upc
+	select {
+	case <-b.upc:
+	default:
+		// terminate all waiting Get()s
+		close(b.upc)
+	}
+
+	b.mu.Unlock()
+
+	// wait for updateNotifyLoop to finish
+	<-b.donec
+	close(b.notifyCh)
+
+	return nil
+}
+
+func getHost(ep string) string {
+	url, uerr := url.Parse(ep)
+	if uerr != nil || !strings.Contains(ep, "://") {
+		return ep
+	}
+	return url.Host
+}

vendor/github.com/coreos/etcd/clientv3/client.go

@@ -0,0 +1,515 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/metadata"
+)
+
+var (
+	ErrNoAvailableEndpoints = errors.New("etcdclient: no available endpoints")
+	ErrOldCluster           = errors.New("etcdclient: old cluster version")
+)
+
+// Client provides and manages an etcd v3 client session.
+type Client struct {
+	Cluster
+	KV
+	Lease
+	Watcher
+	Auth
+	Maintenance
+
+	conn     *grpc.ClientConn
+	dialerrc chan error
+
+	cfg              Config
+	creds            *credentials.TransportCredentials
+	balancer         *simpleBalancer
+	retryWrapper     retryRpcFunc
+	retryAuthWrapper retryRpcFunc
+
+	ctx    context.Context
+	cancel context.CancelFunc
+
+	// Username is a username for authentication
+	Username string
+	// Password is a password for authentication
+	Password string
+	// tokenCred is an instance of WithPerRPCCredentials()'s argument
+	tokenCred *authTokenCredential
+}
+
+// New creates a new etcdv3 client from a given configuration.
+func New(cfg Config) (*Client, error) {
+	if len(cfg.Endpoints) == 0 {
+		return nil, ErrNoAvailableEndpoints
+	}
+
+	return newClient(&cfg)
+}
+
+// NewCtxClient creates a client with a context but no underlying grpc
+// connection. This is useful for embedded cases that override the
+// service interface implementations and do not need connection management.
+func NewCtxClient(ctx context.Context) *Client {
+	cctx, cancel := context.WithCancel(ctx)
+	return &Client{ctx: cctx, cancel: cancel}
+}
+
+// NewFromURL creates a new etcdv3 client from a URL.
+func NewFromURL(url string) (*Client, error) {
+	return New(Config{Endpoints: []string{url}})
+}
+
+// Close shuts down the client's etcd connections.
+func (c *Client) Close() error {
+	c.cancel()
+	c.Watcher.Close()
+	c.Lease.Close()
+	if c.conn != nil {
+		return toErr(c.ctx, c.conn.Close())
+	}
+	return c.ctx.Err()
+}
+
+// Ctx is a context for "out of band" messages (e.g., for sending
+// "clean up" message when another context is canceled). It is
+// canceled on client Close().
+func (c *Client) Ctx() context.Context { return c.ctx }
+
+// Endpoints lists the registered endpoints for the client.
+func (c *Client) Endpoints() (eps []string) {
+	// copy the slice; protect original endpoints from being changed
+	eps = make([]string, len(c.cfg.Endpoints))
+	copy(eps, c.cfg.Endpoints)
+	return
+}
+
+// SetEndpoints updates client's endpoints.
+func (c *Client) SetEndpoints(eps ...string) {
+	c.cfg.Endpoints = eps
+	c.balancer.updateAddrs(eps)
+}
+
+// Sync synchronizes client's endpoints with the known endpoints from the etcd membership.
+func (c *Client) Sync(ctx context.Context) error {
+	mresp, err := c.MemberList(ctx)
+	if err != nil {
+		return err
+	}
+	var eps []string
+	for _, m := range mresp.Members {
+		eps = append(eps, m.ClientURLs...)
+	}
+	c.SetEndpoints(eps...)
+	return nil
+}
+
+func (c *Client) autoSync() {
+	if c.cfg.AutoSyncInterval == time.Duration(0) {
+		return
+	}
+
+	for {
+		select {
+		case <-c.ctx.Done():
+			return
+		case <-time.After(c.cfg.AutoSyncInterval):
+			ctx, _ := context.WithTimeout(c.ctx, 5*time.Second)
+			if err := c.Sync(ctx); err != nil && err != c.ctx.Err() {
+				logger.Println("Auto sync endpoints failed:", err)
+			}
+		}
+	}
+}
+
+type authTokenCredential struct {
+	token   string
+	tokenMu *sync.RWMutex
+}
+
+func (cred authTokenCredential) RequireTransportSecurity() bool {
+	return false
+}
+
+func (cred authTokenCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
+	cred.tokenMu.RLock()
+	defer cred.tokenMu.RUnlock()
+	return map[string]string{
+		"token": cred.token,
+	}, nil
+}
+
+func parseEndpoint(endpoint string) (proto string, host string, scheme string) {
+	proto = "tcp"
+	host = endpoint
+	url, uerr := url.Parse(endpoint)
+	if uerr != nil || !strings.Contains(endpoint, "://") {
+		return
+	}
+	scheme = url.Scheme
+
+	// strip scheme:// prefix since grpc dials by host
+	host = url.Host
+	switch url.Scheme {
+	case "http", "https":
+	case "unix", "unixs":
+		proto = "unix"
+		host = url.Host + url.Path
+	default:
+		proto, host = "", ""
+	}
+	return
+}
+
+func (c *Client) processCreds(scheme string) (creds *credentials.TransportCredentials) {
+	creds = c.creds
+	switch scheme {
+	case "unix":
+	case "http":
+		creds = nil
+	case "https", "unixs":
+		if creds != nil {
+			break
+		}
+		tlsconfig := &tls.Config{}
+		emptyCreds := credentials.NewTLS(tlsconfig)
+		creds = &emptyCreds
+	default:
+		creds = nil
+	}
+	return
+}
+
+// dialSetupOpts gives the dial opts prior to any authentication
+func (c *Client) dialSetupOpts(endpoint string, dopts ...grpc.DialOption) (opts []grpc.DialOption) {
+	if c.cfg.DialTimeout > 0 {
+		opts = []grpc.DialOption{grpc.WithTimeout(c.cfg.DialTimeout)}
+	}
+	opts = append(opts, dopts...)
+
+	f := func(host string, t time.Duration) (net.Conn, error) {
+		proto, host, _ := parseEndpoint(c.balancer.getEndpoint(host))
+		if host == "" && endpoint != "" {
+			// dialing an endpoint not in the balancer; use
+			// endpoint passed into dial
+			proto, host, _ = parseEndpoint(endpoint)
+		}
+		if proto == "" {
+			return nil, fmt.Errorf("unknown scheme for %q", host)
+		}
+		select {
+		case <-c.ctx.Done():
+			return nil, c.ctx.Err()
+		default:
+		}
+		dialer := &net.Dialer{Timeout: t}
+		conn, err := dialer.DialContext(c.ctx, proto, host)
+		if err != nil {
+			select {
+			case c.dialerrc <- err:
+			default:
+			}
+		}
+		return conn, err
+	}
+	opts = append(opts, grpc.WithDialer(f))
+
+	creds := c.creds
+	if _, _, scheme := parseEndpoint(endpoint); len(scheme) != 0 {
+		creds = c.processCreds(scheme)
+	}
+	if creds != nil {
+		opts = append(opts, grpc.WithTransportCredentials(*creds))
+	} else {
+		opts = append(opts, grpc.WithInsecure())
+	}
+
+	return opts
+}
+
+// Dial connects to a single endpoint using the client's config.
+func (c *Client) Dial(endpoint string) (*grpc.ClientConn, error) {
+	return c.dial(endpoint)
+}
+
+func (c *Client) getToken(ctx context.Context) error {
+	var err error // return last error in a case of fail
+	var auth *authenticator
+
+	for i := 0; i < len(c.cfg.Endpoints); i++ {
+		endpoint := c.cfg.Endpoints[i]
+		host := getHost(endpoint)
+		// use dial options without dopts to avoid reusing the client balancer
+		auth, err = newAuthenticator(host, c.dialSetupOpts(endpoint))
+		if err != nil {
+			continue
+		}
+		defer auth.close()
+
+		var resp *AuthenticateResponse
+		resp, err = auth.authenticate(ctx, c.Username, c.Password)
+		if err != nil {
+			continue
+		}
+
+		c.tokenCred.tokenMu.Lock()
+		c.tokenCred.token = resp.Token
+		c.tokenCred.tokenMu.Unlock()
+
+		return nil
+	}
+
+	return err
+}
+
+func (c *Client) dial(endpoint string, dopts ...grpc.DialOption) (*grpc.ClientConn, error) {
+	opts := c.dialSetupOpts(endpoint, dopts...)
+	host := getHost(endpoint)
+	if c.Username != "" && c.Password != "" {
+		c.tokenCred = &authTokenCredential{
+			tokenMu: &sync.RWMutex{},
+		}
+
+		ctx := c.ctx
+		if c.cfg.DialTimeout > 0 {
+			cctx, cancel := context.WithTimeout(ctx, c.cfg.DialTimeout)
+			defer cancel()
+			ctx = cctx
+		}
+
+		err := c.getToken(ctx)
+		if err != nil {
+			if toErr(ctx, err) != rpctypes.ErrAuthNotEnabled {
+				if err == ctx.Err() && ctx.Err() != c.ctx.Err() {
+					err = grpc.ErrClientConnTimeout
+				}
+				return nil, err
+			}
+		} else {
+			opts = append(opts, grpc.WithPerRPCCredentials(c.tokenCred))
+		}
+	}
+
+	opts = append(opts, c.cfg.DialOptions...)
+
+	conn, err := grpc.DialContext(c.ctx, host, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return conn, nil
+}
+
+// WithRequireLeader requires client requests to only succeed
+// when the cluster has a leader.
+func WithRequireLeader(ctx context.Context) context.Context {
+	md := metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+	return metadata.NewContext(ctx, md)
+}
+
+func newClient(cfg *Config) (*Client, error) {
+	if cfg == nil {
+		cfg = &Config{}
+	}
+	var creds *credentials.TransportCredentials
+	if cfg.TLS != nil {
+		c := credentials.NewTLS(cfg.TLS)
+		creds = &c
+	}
+
+	// use a temporary skeleton client to bootstrap first connection
+	baseCtx := context.TODO()
+	if cfg.Context != nil {
+		baseCtx = cfg.Context
+	}
+
+	ctx, cancel := context.WithCancel(baseCtx)
+	client := &Client{
+		conn:     nil,
+		dialerrc: make(chan error, 1),
+		cfg:      *cfg,
+		creds:    creds,
+		ctx:      ctx,
+		cancel:   cancel,
+	}
+	if cfg.Username != "" && cfg.Password != "" {
+		client.Username = cfg.Username
+		client.Password = cfg.Password
+	}
+
+	client.balancer = newSimpleBalancer(cfg.Endpoints)
+	// use Endpoints[0] so that for https:// without any tls config given, then
+	// grpc will assume the ServerName is in the endpoint.
+	conn, err := client.dial(cfg.Endpoints[0], grpc.WithBalancer(client.balancer))
+	if err != nil {
+		client.cancel()
+		client.balancer.Close()
+		return nil, err
+	}
+	client.conn = conn
+	client.retryWrapper = client.newRetryWrapper()
+	client.retryAuthWrapper = client.newAuthRetryWrapper()
+
+	// wait for a connection
+	if cfg.DialTimeout > 0 {
+		hasConn := false
+		waitc := time.After(cfg.DialTimeout)
+		select {
+		case <-client.balancer.readyc:
+			hasConn = true
+		case <-ctx.Done():
+		case <-waitc:
+		}
+		if !hasConn {
+			err := grpc.ErrClientConnTimeout
+			select {
+			case err = <-client.dialerrc:
+			default:
+			}
+			client.cancel()
+			client.balancer.Close()
+			conn.Close()
+			return nil, err
+		}
+	}
+
+	client.Cluster = NewCluster(client)
+	client.KV = NewKV(client)
+	client.Lease = NewLease(client)
+	client.Watcher = NewWatcher(client)
+	client.Auth = NewAuth(client)
+	client.Maintenance = NewMaintenance(client)
+
+	if cfg.RejectOldCluster {
+		if err := client.checkVersion(); err != nil {
+			client.Close()
+			return nil, err
+		}
+	}
+
+	go client.autoSync()
+	return client, nil
+}
+
+func (c *Client) checkVersion() (err error) {
+	var wg sync.WaitGroup
+	errc := make(chan error, len(c.cfg.Endpoints))
+	ctx, cancel := context.WithCancel(c.ctx)
+	if c.cfg.DialTimeout > 0 {
+		ctx, _ = context.WithTimeout(ctx, c.cfg.DialTimeout)
+	}
+	wg.Add(len(c.cfg.Endpoints))
+	for _, ep := range c.cfg.Endpoints {
+		// if cluster is current, any endpoint gives a recent version
+		go func(e string) {
+			defer wg.Done()
+			resp, rerr := c.Status(ctx, e)
+			if rerr != nil {
+				errc <- rerr
+				return
+			}
+			vs := strings.Split(resp.Version, ".")
+			maj, min := 0, 0
+			if len(vs) >= 2 {
+				maj, rerr = strconv.Atoi(vs[0])
+				min, rerr = strconv.Atoi(vs[1])
+			}
+			if maj < 3 || (maj == 3 && min < 2) {
+				rerr = ErrOldCluster
+			}
+			errc <- rerr
+		}(ep)
+	}
+	// wait for success
+	for i := 0; i < len(c.cfg.Endpoints); i++ {
+		if err = <-errc; err == nil {
+			break
+		}
+	}
+	cancel()
+	wg.Wait()
+	return err
+}
+
+// ActiveConnection returns the current in-use connection
+func (c *Client) ActiveConnection() *grpc.ClientConn { return c.conn }
+
+// isHaltErr returns true if the given error and context indicate no forward
+// progress can be made, even after reconnecting.
+func isHaltErr(ctx context.Context, err error) bool {
+	if ctx != nil && ctx.Err() != nil {
+		return true
+	}
+	if err == nil {
+		return false
+	}
+	code := grpc.Code(err)
+	// Unavailable codes mean the system will be right back.
+	// (e.g., can't connect, lost leader)
+	// Treat Internal codes as if something failed, leaving the
+	// system in an inconsistent state, but retrying could make progress.
+	// (e.g., failed in middle of send, corrupted frame)
+	// TODO: are permanent Internal errors possible from grpc?
+	return code != codes.Unavailable && code != codes.Internal
+}
+
+func toErr(ctx context.Context, err error) error {
+	if err == nil {
+		return nil
+	}
+	err = rpctypes.Error(err)
+	if _, ok := err.(rpctypes.EtcdError); ok {
+		return err
+	}
+	code := grpc.Code(err)
+	switch code {
+	case codes.DeadlineExceeded:
+		fallthrough
+	case codes.Canceled:
+		if ctx.Err() != nil {
+			err = ctx.Err()
+		}
+	case codes.Unavailable:
+		err = ErrNoAvailableEndpoints
+	case codes.FailedPrecondition:
+		err = grpc.ErrClientConnClosing
+	}
+	return err
+}
+
+func canceledByCaller(stopCtx context.Context, err error) bool {
+	if stopCtx.Err() == nil || err == nil {
+		return false
+	}
+
+	return err == context.Canceled || err == context.DeadlineExceeded
+}

vendor/github.com/coreos/etcd/clientv3/cluster.go

@@ -0,0 +1,100 @@
+// Copyright 2016 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 clientv3
+
+import (
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type (
+	Member               pb.Member
+	MemberListResponse   pb.MemberListResponse
+	MemberAddResponse    pb.MemberAddResponse
+	MemberRemoveResponse pb.MemberRemoveResponse
+	MemberUpdateResponse pb.MemberUpdateResponse
+)
+
+type Cluster interface {
+	// MemberList lists the current cluster membership.
+	MemberList(ctx context.Context) (*MemberListResponse, error)
+
+	// MemberAdd adds a new member into the cluster.
+	MemberAdd(ctx context.Context, peerAddrs []string) (*MemberAddResponse, error)
+
+	// MemberRemove removes an existing member from the cluster.
+	MemberRemove(ctx context.Context, id uint64) (*MemberRemoveResponse, error)
+
+	// MemberUpdate updates the peer addresses of the member.
+	MemberUpdate(ctx context.Context, id uint64, peerAddrs []string) (*MemberUpdateResponse, error)
+}
+
+type cluster struct {
+	remote pb.ClusterClient
+}
+
+func NewCluster(c *Client) Cluster {
+	return &cluster{remote: RetryClusterClient(c)}
+}
+
+func NewClusterFromClusterClient(remote pb.ClusterClient) Cluster {
+	return &cluster{remote: remote}
+}
+
+func (c *cluster) MemberAdd(ctx context.Context, peerAddrs []string) (*MemberAddResponse, error) {
+	r := &pb.MemberAddRequest{PeerURLs: peerAddrs}
+	resp, err := c.remote.MemberAdd(ctx, r)
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	return (*MemberAddResponse)(resp), nil
+}
+
+func (c *cluster) MemberRemove(ctx context.Context, id uint64) (*MemberRemoveResponse, error) {
+	r := &pb.MemberRemoveRequest{ID: id}
+	resp, err := c.remote.MemberRemove(ctx, r)
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	return (*MemberRemoveResponse)(resp), nil
+}
+
+func (c *cluster) MemberUpdate(ctx context.Context, id uint64, peerAddrs []string) (*MemberUpdateResponse, error) {
+	// it is safe to retry on update.
+	for {
+		r := &pb.MemberUpdateRequest{ID: id, PeerURLs: peerAddrs}
+		resp, err := c.remote.MemberUpdate(ctx, r, grpc.FailFast(false))
+		if err == nil {
+			return (*MemberUpdateResponse)(resp), nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (c *cluster) MemberList(ctx context.Context) (*MemberListResponse, error) {
+	// it is safe to retry on list.
+	for {
+		resp, err := c.remote.MemberList(ctx, &pb.MemberListRequest{}, grpc.FailFast(false))
+		if err == nil {
+			return (*MemberListResponse)(resp), nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}

vendor/github.com/coreos/etcd/clientv3/compact_op.go

@@ -0,0 +1,53 @@
+// Copyright 2016 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 clientv3
+
+import (
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+)
+
+// CompactOp represents a compact operation.
+type CompactOp struct {
+	revision int64
+	physical bool
+}
+
+// CompactOption configures compact operation.
+type CompactOption func(*CompactOp)
+
+func (op *CompactOp) applyCompactOpts(opts []CompactOption) {
+	for _, opt := range opts {
+		opt(op)
+	}
+}
+
+// OpCompact wraps slice CompactOption to create a CompactOp.
+func OpCompact(rev int64, opts ...CompactOption) CompactOp {
+	ret := CompactOp{revision: rev}
+	ret.applyCompactOpts(opts)
+	return ret
+}
+
+func (op CompactOp) toRequest() *pb.CompactionRequest {
+	return &pb.CompactionRequest{Revision: op.revision, Physical: op.physical}
+}
+
+// WithCompactPhysical makes compact RPC call wait until
+// the compaction is physically applied to the local database
+// such that compacted entries are totally removed from the
+// backend database.
+func WithCompactPhysical() CompactOption {
+	return func(op *CompactOp) { op.physical = true }
+}

vendor/github.com/coreos/etcd/clientv3/compare.go

@@ -0,0 +1,110 @@
+// Copyright 2016 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 clientv3
+
+import (
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+)
+
+type CompareTarget int
+type CompareResult int
+
+const (
+	CompareVersion CompareTarget = iota
+	CompareCreated
+	CompareModified
+	CompareValue
+)
+
+type Cmp pb.Compare
+
+func Compare(cmp Cmp, result string, v interface{}) Cmp {
+	var r pb.Compare_CompareResult
+
+	switch result {
+	case "=":
+		r = pb.Compare_EQUAL
+	case "!=":
+		r = pb.Compare_NOT_EQUAL
+	case ">":
+		r = pb.Compare_GREATER
+	case "<":
+		r = pb.Compare_LESS
+	default:
+		panic("Unknown result op")
+	}
+
+	cmp.Result = r
+	switch cmp.Target {
+	case pb.Compare_VALUE:
+		val, ok := v.(string)
+		if !ok {
+			panic("bad compare value")
+		}
+		cmp.TargetUnion = &pb.Compare_Value{Value: []byte(val)}
+	case pb.Compare_VERSION:
+		cmp.TargetUnion = &pb.Compare_Version{Version: mustInt64(v)}
+	case pb.Compare_CREATE:
+		cmp.TargetUnion = &pb.Compare_CreateRevision{CreateRevision: mustInt64(v)}
+	case pb.Compare_MOD:
+		cmp.TargetUnion = &pb.Compare_ModRevision{ModRevision: mustInt64(v)}
+	default:
+		panic("Unknown compare type")
+	}
+	return cmp
+}
+
+func Value(key string) Cmp {
+	return Cmp{Key: []byte(key), Target: pb.Compare_VALUE}
+}
+
+func Version(key string) Cmp {
+	return Cmp{Key: []byte(key), Target: pb.Compare_VERSION}
+}
+
+func CreateRevision(key string) Cmp {
+	return Cmp{Key: []byte(key), Target: pb.Compare_CREATE}
+}
+
+func ModRevision(key string) Cmp {
+	return Cmp{Key: []byte(key), Target: pb.Compare_MOD}
+}
+
+// KeyBytes returns the byte slice holding with the comparison key.
+func (cmp *Cmp) KeyBytes() []byte { return cmp.Key }
+
+// WithKeyBytes sets the byte slice for the comparison key.
+func (cmp *Cmp) WithKeyBytes(key []byte) { cmp.Key = key }
+
+// ValueBytes returns the byte slice holding the comparison value, if any.
+func (cmp *Cmp) ValueBytes() []byte {
+	if tu, ok := cmp.TargetUnion.(*pb.Compare_Value); ok {
+		return tu.Value
+	}
+	return nil
+}
+
+// WithValueBytes sets the byte slice for the comparison's value.
+func (cmp *Cmp) WithValueBytes(v []byte) { cmp.TargetUnion.(*pb.Compare_Value).Value = v }
+
+func mustInt64(val interface{}) int64 {
+	if v, ok := val.(int64); ok {
+		return v
+	}
+	if v, ok := val.(int); ok {
+		return int64(v)
+	}
+	panic("bad value")
+}

vendor/github.com/coreos/etcd/clientv3/concurrency/doc.go

@@ -0,0 +1,17 @@
+// Copyright 2016 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 concurrency implements concurrency operations on top of
+// etcd such as distributed locks, barriers, and elections.
+package concurrency

vendor/github.com/coreos/etcd/clientv3/concurrency/election.go

@@ -0,0 +1,243 @@
+// Copyright 2016 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 concurrency
+
+import (
+	"errors"
+	"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"
+)
+
+var (
+	ErrElectionNotLeader = errors.New("election: not leader")
+	ErrElectionNoLeader  = errors.New("election: no leader")
+)
+
+type Election struct {
+	session *Session
+
+	keyPrefix string
+
+	leaderKey     string
+	leaderRev     int64
+	leaderSession *Session
+	hdr           *pb.ResponseHeader
+}
+
+// NewElection returns a new election on a given key prefix.
+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 {
+	s := e.session
+	client := e.session.Client()
+
+	k := fmt.Sprintf("%s%x", e.keyPrefix, s.Lease())
+	txn := client.Txn(ctx).If(v3.Compare(v3.CreateRevision(k), "=", 0))
+	txn = txn.Then(v3.OpPut(k, val, v3.WithLease(s.Lease())))
+	txn = txn.Else(v3.OpGet(k))
+	resp, err := txn.Commit()
+	if err != nil {
+		return err
+	}
+	e.leaderKey, e.leaderRev, e.leaderSession = k, resp.Header.Revision, s
+	if !resp.Succeeded {
+		kv := resp.Responses[0].GetResponseRange().Kvs[0]
+		e.leaderRev = kv.CreateRevision
+		if string(kv.Value) != val {
+			if err = e.Proclaim(ctx, val); err != nil {
+				e.Resign(ctx)
+				return err
+			}
+		}
+	}
+
+	_, err = waitDeletes(ctx, client, e.keyPrefix, e.leaderRev-1)
+	if err != nil {
+		// clean up in case of context cancel
+		select {
+		case <-ctx.Done():
+			e.Resign(client.Ctx())
+		default:
+			e.leaderSession = nil
+		}
+		return err
+	}
+	e.hdr = resp.Header
+
+	return nil
+}
+
+// Proclaim lets the leader announce a new value without another election.
+func (e *Election) Proclaim(ctx context.Context, val string) error {
+	if e.leaderSession == nil {
+		return ErrElectionNotLeader
+	}
+	client := e.session.Client()
+	cmp := v3.Compare(v3.CreateRevision(e.leaderKey), "=", e.leaderRev)
+	txn := client.Txn(ctx).If(cmp)
+	txn = txn.Then(v3.OpPut(e.leaderKey, val, v3.WithLease(e.leaderSession.Lease())))
+	tresp, terr := txn.Commit()
+	if terr != nil {
+		return terr
+	}
+	if !tresp.Succeeded {
+		e.leaderKey = ""
+		return ErrElectionNotLeader
+	}
+
+	e.hdr = tresp.Header
+	return nil
+}
+
+// Resign lets a leader start a new election.
+func (e *Election) Resign(ctx context.Context) (err error) {
+	if e.leaderSession == nil {
+		return nil
+	}
+	client := e.session.Client()
+	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) (*v3.GetResponse, error) {
+	client := e.session.Client()
+	resp, err := client.Get(ctx, e.keyPrefix, v3.WithFirstCreate()...)
+	if err != nil {
+		return nil, err
+	} else if len(resp.Kvs) == 0 {
+		// no leader currently elected
+		return nil, ErrElectionNoLeader
+	}
+	return resp, nil
+}
+
+// Observe returns a channel that reliably observes ordered leader proposals
+// as GetResponse values on every current elected leader key. It will not
+// necessarily fetch all historical leader updates, but will always post the
+// most recent leader value.
+//
+// The channel closes when the context is canceled or the underlying watcher
+// is otherwise disrupted.
+func (e *Election) Observe(ctx context.Context) <-chan v3.GetResponse {
+	retc := make(chan v3.GetResponse)
+	go e.observe(ctx, retc)
+	return retc
+}
+
+func (e *Election) observe(ctx context.Context, ch chan<- v3.GetResponse) {
+	client := e.session.Client()
+
+	defer close(ch)
+	for {
+		resp, err := client.Get(ctx, e.keyPrefix, v3.WithFirstCreate()...)
+		if err != nil {
+			return
+		}
+
+		var kv *mvccpb.KeyValue
+		var hdr *pb.ResponseHeader
+
+		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 {
+					cancel()
+					return
+				}
+				// only accept PUTs; a DELETE will make observe() spin
+				for _, ev := range wr.Events {
+					if ev.Type == mvccpb.PUT {
+						hdr, kv = &wr.Header, ev.Kv
+						// may have multiple revs; hdr.rev = the last rev
+						// set to kv's rev in case batch has multiple PUTs
+						hdr.Revision = kv.ModRevision
+						break
+					}
+				}
+			}
+			cancel()
+		} else {
+			hdr, kv = resp.Header, resp.Kvs[0]
+		}
+
+		select {
+		case ch <- v3.GetResponse{Header: hdr, Kvs: []*mvccpb.KeyValue{kv}}:
+		case <-ctx.Done():
+			return
+		}
+
+		cctx, cancel := context.WithCancel(ctx)
+		wch := client.Watch(cctx, string(kv.Key), v3.WithRev(hdr.Revision+1))
+		keyDeleted := false
+		for !keyDeleted {
+			wr, ok := <-wch
+			if !ok {
+				return
+			}
+			for _, ev := range wr.Events {
+				if ev.Type == mvccpb.DELETE {
+					keyDeleted = true
+					break
+				}
+				resp.Header = &wr.Header
+				resp.Kvs = []*mvccpb.KeyValue{ev.Kv}
+				select {
+				case ch <- *resp:
+				case <-cctx.Done():
+					return
+				}
+			}
+		}
+		cancel()
+	}
+}
+
+// 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 }

vendor/github.com/coreos/etcd/clientv3/concurrency/key.go

@@ -0,0 +1,65 @@
+// Copyright 2016 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 concurrency
+
+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"
+)
+
+func waitDelete(ctx context.Context, client *v3.Client, key string, rev int64) error {
+	cctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	var wr v3.WatchResponse
+	wch := client.Watch(cctx, key, v3.WithRev(rev))
+	for wr = range wch {
+		for _, ev := range wr.Events {
+			if ev.Type == mvccpb.DELETE {
+				return nil
+			}
+		}
+	}
+	if err := wr.Err(); err != nil {
+		return err
+	}
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	return fmt.Errorf("lost watcher waiting for delete")
+}
+
+// waitDeletes efficiently waits until all keys matching the prefix and no greater
+// than the create revision.
+func waitDeletes(ctx context.Context, client *v3.Client, pfx string, maxCreateRev int64) (*pb.ResponseHeader, error) {
+	getOpts := append(v3.WithLastCreate(), v3.WithMaxCreateRev(maxCreateRev))
+	for {
+		resp, err := client.Get(ctx, pfx, getOpts...)
+		if err != nil {
+			return nil, err
+		}
+		if len(resp.Kvs) == 0 {
+			return resp.Header, nil
+		}
+		lastKey := string(resp.Kvs[0].Key)
+		if err = waitDelete(ctx, client, lastKey, resp.Header.Revision); err != nil {
+			return nil, err
+		}
+	}
+}

vendor/github.com/coreos/etcd/clientv3/concurrency/mutex.go

@@ -0,0 +1,110 @@
+// Copyright 2016 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 concurrency
+
+import (
+	"fmt"
+	"sync"
+
+	v3 "github.com/coreos/etcd/clientv3"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+)
+
+// Mutex implements the sync Locker interface with etcd
+type Mutex struct {
+	s *Session
+
+	pfx   string
+	myKey string
+	myRev int64
+	hdr   *pb.ResponseHeader
+}
+
+func NewMutex(s *Session, pfx string) *Mutex {
+	return &Mutex{s, pfx + "/", "", -1, nil}
+}
+
+// Lock locks the mutex with a cancelable context. If the context is canceled
+// while trying to acquire the lock, the mutex tries to clean its stale lock entry.
+func (m *Mutex) Lock(ctx context.Context) error {
+	s := m.s
+	client := m.s.Client()
+
+	m.myKey = fmt.Sprintf("%s%x", m.pfx, s.Lease())
+	cmp := v3.Compare(v3.CreateRevision(m.myKey), "=", 0)
+	// put self in lock waiters via myKey; oldest waiter holds lock
+	put := v3.OpPut(m.myKey, "", v3.WithLease(s.Lease()))
+	// reuse key in case this session already holds the lock
+	get := v3.OpGet(m.myKey)
+	resp, err := client.Txn(ctx).If(cmp).Then(put).Else(get).Commit()
+	if err != nil {
+		return err
+	}
+	m.myRev = resp.Header.Revision
+	if !resp.Succeeded {
+		m.myRev = resp.Responses[0].GetResponseRange().Kvs[0].CreateRevision
+	}
+
+	// wait for deletion revisions prior to myKey
+	hdr, werr := waitDeletes(ctx, client, m.pfx, m.myRev-1)
+	// release lock key if cancelled
+	select {
+	case <-ctx.Done():
+		m.Unlock(client.Ctx())
+	default:
+		m.hdr = hdr
+	}
+	return werr
+}
+
+func (m *Mutex) Unlock(ctx context.Context) error {
+	client := m.s.Client()
+	if _, err := client.Delete(ctx, m.myKey); err != nil {
+		return err
+	}
+	m.myKey = "\x00"
+	m.myRev = -1
+	return nil
+}
+
+func (m *Mutex) IsOwner() v3.Cmp {
+	return v3.Compare(v3.CreateRevision(m.myKey), "=", m.myRev)
+}
+
+func (m *Mutex) Key() string { return m.myKey }
+
+// Header is the response header received from etcd on acquiring the lock.
+func (m *Mutex) Header() *pb.ResponseHeader { return m.hdr }
+
+type lockerMutex struct{ *Mutex }
+
+func (lm *lockerMutex) Lock() {
+	client := lm.s.Client()
+	if err := lm.Mutex.Lock(client.Ctx()); err != nil {
+		panic(err)
+	}
+}
+func (lm *lockerMutex) Unlock() {
+	client := lm.s.Client()
+	if err := lm.Mutex.Unlock(client.Ctx()); err != nil {
+		panic(err)
+	}
+}
+
+// NewLocker creates a sync.Locker backed by an etcd mutex.
+func NewLocker(s *Session, pfx string) sync.Locker {
+	return &lockerMutex{NewMutex(s, pfx)}
+}

vendor/github.com/coreos/etcd/clientv3/concurrency/session.go

@@ -0,0 +1,140 @@
+// Copyright 2016 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 concurrency
+
+import (
+	"time"
+
+	v3 "github.com/coreos/etcd/clientv3"
+	"golang.org/x/net/context"
+)
+
+const defaultSessionTTL = 60
+
+// Session represents a lease kept alive for the lifetime of a client.
+// Fault-tolerant applications may use sessions to reason about liveness.
+type Session struct {
+	client *v3.Client
+	opts   *sessionOptions
+	id     v3.LeaseID
+
+	cancel context.CancelFunc
+	donec  <-chan struct{}
+}
+
+// NewSession gets the leased session for a client.
+func NewSession(client *v3.Client, opts ...SessionOption) (*Session, error) {
+	ops := &sessionOptions{ttl: defaultSessionTTL, ctx: client.Ctx()}
+	for _, opt := range opts {
+		opt(ops)
+	}
+
+	id := ops.leaseID
+	if id == v3.NoLease {
+		resp, err := client.Grant(ops.ctx, int64(ops.ttl))
+		if err != nil {
+			return nil, err
+		}
+		id = v3.LeaseID(resp.ID)
+	}
+
+	ctx, cancel := context.WithCancel(ops.ctx)
+	keepAlive, err := client.KeepAlive(ctx, id)
+	if err != nil || keepAlive == nil {
+		return nil, err
+	}
+
+	donec := make(chan struct{})
+	s := &Session{client: client, opts: ops, id: id, cancel: cancel, donec: donec}
+
+	// keep the lease alive until client error or cancelled context
+	go func() {
+		defer close(donec)
+		for range keepAlive {
+			// eat messages until keep alive channel closes
+		}
+	}()
+
+	return s, nil
+}
+
+// Client is the etcd client that is attached to the session.
+func (s *Session) Client() *v3.Client {
+	return s.client
+}
+
+// Lease is the lease ID for keys bound to the session.
+func (s *Session) Lease() v3.LeaseID { return s.id }
+
+// Done returns a channel that closes when the lease is orphaned, expires, or
+// is otherwise no longer being refreshed.
+func (s *Session) Done() <-chan struct{} { return s.donec }
+
+// Orphan ends the refresh for the session lease. This is useful
+// in case the state of the client connection is indeterminate (revoke
+// would fail) or when transferring lease ownership.
+func (s *Session) Orphan() {
+	s.cancel()
+	<-s.donec
+}
+
+// Close orphans the session and revokes the session lease.
+func (s *Session) Close() error {
+	s.Orphan()
+	// if revoke takes longer than the ttl, lease is expired anyway
+	ctx, cancel := context.WithTimeout(s.opts.ctx, time.Duration(s.opts.ttl)*time.Second)
+	_, err := s.client.Revoke(ctx, s.id)
+	cancel()
+	return err
+}
+
+type sessionOptions struct {
+	ttl     int
+	leaseID v3.LeaseID
+	ctx     context.Context
+}
+
+// SessionOption configures Session.
+type SessionOption func(*sessionOptions)
+
+// WithTTL configures the session's TTL in seconds.
+// If TTL is <= 0, the default 60 seconds TTL will be used.
+func WithTTL(ttl int) SessionOption {
+	return func(so *sessionOptions) {
+		if ttl > 0 {
+			so.ttl = ttl
+		}
+	}
+}
+
+// WithLease specifies the existing leaseID to be used for the session.
+// This is useful in process restart scenario, for example, to reclaim
+// leadership from an election prior to restart.
+func WithLease(leaseID v3.LeaseID) SessionOption {
+	return func(so *sessionOptions) {
+		so.leaseID = leaseID
+	}
+}
+
+// WithContext assigns a context to the session instead of defaulting to
+// using the client context. This is useful for canceling NewSession and
+// Close operations immediately without having to close the client. If the
+// context is canceled before Close() completes, the session's lease will be
+// abandoned and left to expire instead of being revoked.
+func WithContext(ctx context.Context) SessionOption {
+	return func(so *sessionOptions) {
+		so.ctx = ctx
+	}
+}

vendor/github.com/coreos/etcd/clientv3/concurrency/stm.go

@@ -0,0 +1,387 @@
+// Copyright 2016 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 concurrency
+
+import (
+	"math"
+
+	v3 "github.com/coreos/etcd/clientv3"
+	"golang.org/x/net/context"
+)
+
+// STM is an interface for software transactional memory.
+type STM interface {
+	// Get returns the value for a key and inserts the key in the txn's read set.
+	// If Get fails, it aborts the transaction with an error, never returning.
+	Get(key ...string) string
+	// Put adds a value for a key to the write set.
+	Put(key, val string, opts ...v3.OpOption)
+	// Rev returns the revision of a key in the read set.
+	Rev(key string) int64
+	// Del deletes a key.
+	Del(key string)
+
+	// commit attempts to apply the txn's changes to the server.
+	commit() *v3.TxnResponse
+	reset()
+}
+
+// Isolation is an enumeration of transactional isolation levels which
+// describes how transactions should interfere and conflict.
+type Isolation int
+
+const (
+	// SerializableSnapshot provides serializable isolation and also checks
+	// for write conflicts.
+	SerializableSnapshot Isolation = iota
+	// Serializable reads within the same transactiona attempt return data
+	// from the at the revision of the first read.
+	Serializable
+	// RepeatableReads reads within the same transaction attempt always
+	// return the same data.
+	RepeatableReads
+	// ReadCommitted reads keys from any committed revision.
+	ReadCommitted
+)
+
+// stmError safely passes STM errors through panic to the STM error channel.
+type stmError struct{ err error }
+
+type stmOptions struct {
+	iso      Isolation
+	ctx      context.Context
+	prefetch []string
+}
+
+type stmOption func(*stmOptions)
+
+// WithIsolation specifies the transaction isolation level.
+func WithIsolation(lvl Isolation) stmOption {
+	return func(so *stmOptions) { so.iso = lvl }
+}
+
+// WithAbortContext specifies the context for permanently aborting the transaction.
+func WithAbortContext(ctx context.Context) stmOption {
+	return func(so *stmOptions) { so.ctx = ctx }
+}
+
+// WithPrefetch is a hint to prefetch a list of keys before trying to apply.
+// If an STM transaction will unconditionally fetch a set of keys, prefetching
+// those keys will save the round-trip cost from requesting each key one by one
+// with Get().
+func WithPrefetch(keys ...string) stmOption {
+	return func(so *stmOptions) { so.prefetch = append(so.prefetch, keys...) }
+}
+
+// NewSTM initiates a new STM instance, using snapshot isolation by default.
+func NewSTM(c *v3.Client, apply func(STM) error, so ...stmOption) (*v3.TxnResponse, error) {
+	opts := &stmOptions{ctx: c.Ctx()}
+	for _, f := range so {
+		f(opts)
+	}
+	if len(opts.prefetch) != 0 {
+		f := apply
+		apply = func(s STM) error {
+			s.Get(opts.prefetch...)
+			return f(s)
+		}
+	}
+	return runSTM(mkSTM(c, opts), apply)
+}
+
+func mkSTM(c *v3.Client, opts *stmOptions) STM {
+	switch opts.iso {
+	case SerializableSnapshot:
+		s := &stmSerializable{
+			stm:      stm{client: c, ctx: opts.ctx},
+			prefetch: make(map[string]*v3.GetResponse),
+		}
+		s.conflicts = func() []v3.Cmp {
+			return append(s.rset.cmps(), s.wset.cmps(s.rset.first()+1)...)
+		}
+		return s
+	case Serializable:
+		s := &stmSerializable{
+			stm:      stm{client: c, ctx: opts.ctx},
+			prefetch: make(map[string]*v3.GetResponse),
+		}
+		s.conflicts = func() []v3.Cmp { return s.rset.cmps() }
+		return s
+	case RepeatableReads:
+		s := &stm{client: c, ctx: opts.ctx, getOpts: []v3.OpOption{v3.WithSerializable()}}
+		s.conflicts = func() []v3.Cmp { return s.rset.cmps() }
+		return s
+	case ReadCommitted:
+		s := &stm{client: c, ctx: opts.ctx, getOpts: []v3.OpOption{v3.WithSerializable()}}
+		s.conflicts = func() []v3.Cmp { return nil }
+		return s
+	default:
+		panic("unsupported stm")
+	}
+}
+
+type stmResponse struct {
+	resp *v3.TxnResponse
+	err  error
+}
+
+func runSTM(s STM, apply func(STM) error) (*v3.TxnResponse, error) {
+	outc := make(chan stmResponse, 1)
+	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				e, ok := r.(stmError)
+				if !ok {
+					// client apply panicked
+					panic(r)
+				}
+				outc <- stmResponse{nil, e.err}
+			}
+		}()
+		var out stmResponse
+		for {
+			s.reset()
+			if out.err = apply(s); out.err != nil {
+				break
+			}
+			if out.resp = s.commit(); out.resp != nil {
+				break
+			}
+		}
+		outc <- out
+	}()
+	r := <-outc
+	return r.resp, r.err
+}
+
+// stm implements repeatable-read software transactional memory over etcd
+type stm struct {
+	client *v3.Client
+	ctx    context.Context
+	// rset holds read key values and revisions
+	rset readSet
+	// wset holds overwritten keys and their values
+	wset writeSet
+	// getOpts are the opts used for gets
+	getOpts []v3.OpOption
+	// conflicts computes the current conflicts on the txn
+	conflicts func() []v3.Cmp
+}
+
+type stmPut struct {
+	val string
+	op  v3.Op
+}
+
+type readSet map[string]*v3.GetResponse
+
+func (rs readSet) add(keys []string, txnresp *v3.TxnResponse) {
+	for i, resp := range txnresp.Responses {
+		rs[keys[i]] = (*v3.GetResponse)(resp.GetResponseRange())
+	}
+}
+
+// first returns the store revision from the first fetch
+func (rs readSet) first() int64 {
+	ret := int64(math.MaxInt64 - 1)
+	for _, resp := range rs {
+		if rev := resp.Header.Revision; rev < ret {
+			ret = rev
+		}
+	}
+	return ret
+}
+
+// cmps guards the txn from updates to read set
+func (rs readSet) cmps() []v3.Cmp {
+	cmps := make([]v3.Cmp, 0, len(rs))
+	for k, rk := range rs {
+		cmps = append(cmps, isKeyCurrent(k, rk))
+	}
+	return cmps
+}
+
+type writeSet map[string]stmPut
+
+func (ws writeSet) get(keys ...string) *stmPut {
+	for _, key := range keys {
+		if wv, ok := ws[key]; ok {
+			return &wv
+		}
+	}
+	return nil
+}
+
+// cmps returns a cmp list testing no writes have happened past rev
+func (ws writeSet) cmps(rev int64) []v3.Cmp {
+	cmps := make([]v3.Cmp, 0, len(ws))
+	for key := range ws {
+		cmps = append(cmps, v3.Compare(v3.ModRevision(key), "<", rev))
+	}
+	return cmps
+}
+
+// puts is the list of ops for all pending writes
+func (ws writeSet) puts() []v3.Op {
+	puts := make([]v3.Op, 0, len(ws))
+	for _, v := range ws {
+		puts = append(puts, v.op)
+	}
+	return puts
+}
+
+func (s *stm) Get(keys ...string) string {
+	if wv := s.wset.get(keys...); wv != nil {
+		return wv.val
+	}
+	return respToValue(s.fetch(keys...))
+}
+
+func (s *stm) Put(key, val string, opts ...v3.OpOption) {
+	s.wset[key] = stmPut{val, v3.OpPut(key, val, opts...)}
+}
+
+func (s *stm) Del(key string) { s.wset[key] = stmPut{"", v3.OpDelete(key)} }
+
+func (s *stm) Rev(key string) int64 {
+	if resp := s.fetch(key); resp != nil && len(resp.Kvs) != 0 {
+		return resp.Kvs[0].ModRevision
+	}
+	return 0
+}
+
+func (s *stm) commit() *v3.TxnResponse {
+	txnresp, err := s.client.Txn(s.ctx).If(s.conflicts()...).Then(s.wset.puts()...).Commit()
+	if err != nil {
+		panic(stmError{err})
+	}
+	if txnresp.Succeeded {
+		return txnresp
+	}
+	return nil
+}
+
+func (s *stm) fetch(keys ...string) *v3.GetResponse {
+	if len(keys) == 0 {
+		return nil
+	}
+	ops := make([]v3.Op, len(keys))
+	for i, key := range keys {
+		if resp, ok := s.rset[key]; ok {
+			return resp
+		}
+		ops[i] = v3.OpGet(key, s.getOpts...)
+	}
+	txnresp, err := s.client.Txn(s.ctx).Then(ops...).Commit()
+	if err != nil {
+		panic(stmError{err})
+	}
+	s.rset.add(keys, txnresp)
+	return (*v3.GetResponse)(txnresp.Responses[0].GetResponseRange())
+}
+
+func (s *stm) reset() {
+	s.rset = make(map[string]*v3.GetResponse)
+	s.wset = make(map[string]stmPut)
+}
+
+type stmSerializable struct {
+	stm
+	prefetch map[string]*v3.GetResponse
+}
+
+func (s *stmSerializable) Get(keys ...string) string {
+	if wv := s.wset.get(keys...); wv != nil {
+		return wv.val
+	}
+	firstRead := len(s.rset) == 0
+	for _, key := range keys {
+		if resp, ok := s.prefetch[key]; ok {
+			delete(s.prefetch, key)
+			s.rset[key] = resp
+		}
+	}
+	resp := s.stm.fetch(keys...)
+	if firstRead {
+		// txn's base revision is defined by the first read
+		s.getOpts = []v3.OpOption{
+			v3.WithRev(resp.Header.Revision),
+			v3.WithSerializable(),
+		}
+	}
+	return respToValue(resp)
+}
+
+func (s *stmSerializable) Rev(key string) int64 {
+	s.Get(key)
+	return s.stm.Rev(key)
+}
+
+func (s *stmSerializable) gets() ([]string, []v3.Op) {
+	keys := make([]string, 0, len(s.rset))
+	ops := make([]v3.Op, 0, len(s.rset))
+	for k := range s.rset {
+		keys = append(keys, k)
+		ops = append(ops, v3.OpGet(k))
+	}
+	return keys, ops
+}
+
+func (s *stmSerializable) commit() *v3.TxnResponse {
+	keys, getops := s.gets()
+	txn := s.client.Txn(s.ctx).If(s.conflicts()...).Then(s.wset.puts()...)
+	// use Else to prefetch keys in case of conflict to save a round trip
+	txnresp, err := txn.Else(getops...).Commit()
+	if err != nil {
+		panic(stmError{err})
+	}
+	if txnresp.Succeeded {
+		return txnresp
+	}
+	// load prefetch with Else data
+	s.rset.add(keys, txnresp)
+	s.prefetch = s.rset
+	s.getOpts = nil
+	return nil
+}
+
+func isKeyCurrent(k string, r *v3.GetResponse) v3.Cmp {
+	if len(r.Kvs) != 0 {
+		return v3.Compare(v3.ModRevision(k), "=", r.Kvs[0].ModRevision)
+	}
+	return v3.Compare(v3.ModRevision(k), "=", 0)
+}
+
+func respToValue(resp *v3.GetResponse) string {
+	if resp == nil || len(resp.Kvs) == 0 {
+		return ""
+	}
+	return string(resp.Kvs[0].Value)
+}
+
+// NewSTMRepeatable is deprecated.
+func NewSTMRepeatable(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error) {
+	return NewSTM(c, apply, WithAbortContext(ctx), WithIsolation(RepeatableReads))
+}
+
+// NewSTMSerializable is deprecated.
+func NewSTMSerializable(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error) {
+	return NewSTM(c, apply, WithAbortContext(ctx), WithIsolation(Serializable))
+}
+
+// NewSTMReadCommitted is deprecated.
+func NewSTMReadCommitted(ctx context.Context, c *v3.Client, apply func(STM) error) (*v3.TxnResponse, error) {
+	return NewSTM(c, apply, WithAbortContext(ctx), WithIsolation(ReadCommitted))
+}

vendor/github.com/coreos/etcd/clientv3/config.go

@@ -0,0 +1,54 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"crypto/tls"
+	"time"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type Config struct {
+	// Endpoints is a list of URLs.
+	Endpoints []string `json:"endpoints"`
+
+	// AutoSyncInterval is the interval to update endpoints with its latest members.
+	// 0 disables auto-sync. By default auto-sync is disabled.
+	AutoSyncInterval time.Duration `json:"auto-sync-interval"`
+
+	// DialTimeout is the timeout for failing to establish a connection.
+	DialTimeout time.Duration `json:"dial-timeout"`
+
+	// TLS holds the client secure credentials, if any.
+	TLS *tls.Config
+
+	// Username is a username for authentication.
+	Username string `json:"username"`
+
+	// Password is a password for authentication.
+	Password string `json:"password"`
+
+	// RejectOldCluster when set will refuse to create a client against an outdated cluster.
+	RejectOldCluster bool `json:"reject-old-cluster"`
+
+	// DialOptions is a list of dial options for the grpc client (e.g., for interceptors).
+	DialOptions []grpc.DialOption
+
+	// Context is the default client context; it can be used to cancel grpc dial out and
+	// other operations that do not have an explicit context.
+	Context context.Context
+}

vendor/github.com/coreos/etcd/clientv3/doc.go

@@ -0,0 +1,64 @@
+// Copyright 2016 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 clientv3 implements the official Go etcd client for v3.
+//
+// Create client using `clientv3.New`:
+//
+//	cli, err := clientv3.New(clientv3.Config{
+//		Endpoints:   []string{"localhost:2379", "localhost:22379", "localhost:32379"},
+//		DialTimeout: 5 * time.Second,
+//	})
+//	if err != nil {
+//		// handle error!
+//	}
+//	defer cli.Close()
+//
+// Make sure to close the client after using it. If the client is not closed, the
+// connection will have leaky goroutines.
+//
+// To specify client request timeout, pass context.WithTimeout to APIs:
+//
+//	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+//	resp, err := kvc.Put(ctx, "sample_key", "sample_value")
+//	cancel()
+//	if err != nil {
+//	    // handle error!
+//	}
+//	// use the response
+//
+// The Client has internal state (watchers and leases), so Clients should be reused instead of created as needed.
+// Clients are safe for concurrent use by multiple goroutines.
+//
+// etcd client returns 2 types of errors:
+//
+//	1. context error: canceled or deadline exceeded.
+//	2. gRPC error: see https://github.com/coreos/etcd/blob/master/etcdserver/api/v3rpc/rpctypes/error.go
+//
+// Here is the example code to handle client errors:
+//
+//	resp, err := kvc.Put(ctx, "", "")
+//	if err != nil {
+//		if err == context.Canceled {
+//			// ctx is canceled by another routine
+//		} else if err == context.DeadlineExceeded {
+//			// ctx is attached with a deadline and it exceeded
+//		} else if verr, ok := err.(*v3rpc.ErrEmptyKey); ok {
+//			// process (verr.Errors)
+//		} else {
+//			// bad cluster endpoints, which are not etcd servers
+//		}
+//	}
+//
+package clientv3

vendor/github.com/coreos/etcd/clientv3/kv.go

@@ -0,0 +1,162 @@
+// 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 clientv3
+
+import (
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type (
+	CompactResponse pb.CompactionResponse
+	PutResponse     pb.PutResponse
+	GetResponse     pb.RangeResponse
+	DeleteResponse  pb.DeleteRangeResponse
+	TxnResponse     pb.TxnResponse
+)
+
+type KV interface {
+	// Put puts a key-value pair into etcd.
+	// Note that key,value can be plain bytes array and string is
+	// an immutable representation of that bytes array.
+	// To get a string of bytes, do string([]byte{0x10, 0x20}).
+	Put(ctx context.Context, key, val string, opts ...OpOption) (*PutResponse, error)
+
+	// Get retrieves keys.
+	// By default, Get will return the value for "key", if any.
+	// When passed WithRange(end), Get will return the keys in the range [key, end).
+	// When passed WithFromKey(), Get returns keys greater than or equal to key.
+	// When passed WithRev(rev) with rev > 0, Get retrieves keys at the given revision;
+	// if the required revision is compacted, the request will fail with ErrCompacted .
+	// When passed WithLimit(limit), the number of returned keys is bounded by limit.
+	// When passed WithSort(), the keys will be sorted.
+	Get(ctx context.Context, key string, opts ...OpOption) (*GetResponse, error)
+
+	// Delete deletes a key, or optionally using WithRange(end), [key, end).
+	Delete(ctx context.Context, key string, opts ...OpOption) (*DeleteResponse, error)
+
+	// Compact compacts etcd KV history before the given rev.
+	Compact(ctx context.Context, rev int64, opts ...CompactOption) (*CompactResponse, error)
+
+	// Do applies a single Op on KV without a transaction.
+	// Do is useful when creating arbitrary operations to be issued at a
+	// later time; the user can range over the operations, calling Do to
+	// execute them. Get/Put/Delete, on the other hand, are best suited
+	// for when the operation should be issued at the time of declaration.
+	Do(ctx context.Context, op Op) (OpResponse, error)
+
+	// Txn creates a transaction.
+	Txn(ctx context.Context) Txn
+}
+
+type OpResponse struct {
+	put *PutResponse
+	get *GetResponse
+	del *DeleteResponse
+}
+
+func (op OpResponse) Put() *PutResponse    { return op.put }
+func (op OpResponse) Get() *GetResponse    { return op.get }
+func (op OpResponse) Del() *DeleteResponse { return op.del }
+
+type kv struct {
+	remote pb.KVClient
+}
+
+func NewKV(c *Client) KV {
+	return &kv{remote: RetryKVClient(c)}
+}
+
+func NewKVFromKVClient(remote pb.KVClient) KV {
+	return &kv{remote: remote}
+}
+
+func (kv *kv) Put(ctx context.Context, key, val string, opts ...OpOption) (*PutResponse, error) {
+	r, err := kv.Do(ctx, OpPut(key, val, opts...))
+	return r.put, toErr(ctx, err)
+}
+
+func (kv *kv) Get(ctx context.Context, key string, opts ...OpOption) (*GetResponse, error) {
+	r, err := kv.Do(ctx, OpGet(key, opts...))
+	return r.get, toErr(ctx, err)
+}
+
+func (kv *kv) Delete(ctx context.Context, key string, opts ...OpOption) (*DeleteResponse, error) {
+	r, err := kv.Do(ctx, OpDelete(key, opts...))
+	return r.del, toErr(ctx, err)
+}
+
+func (kv *kv) Compact(ctx context.Context, rev int64, opts ...CompactOption) (*CompactResponse, error) {
+	resp, err := kv.remote.Compact(ctx, OpCompact(rev, opts...).toRequest())
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	return (*CompactResponse)(resp), err
+}
+
+func (kv *kv) Txn(ctx context.Context) Txn {
+	return &txn{
+		kv:  kv,
+		ctx: ctx,
+	}
+}
+
+func (kv *kv) Do(ctx context.Context, op Op) (OpResponse, error) {
+	for {
+		resp, err := kv.do(ctx, op)
+		if err == nil {
+			return resp, nil
+		}
+
+		if isHaltErr(ctx, err) {
+			return resp, toErr(ctx, err)
+		}
+		// do not retry on modifications
+		if op.isWrite() {
+			return resp, toErr(ctx, err)
+		}
+	}
+}
+
+func (kv *kv) do(ctx context.Context, op Op) (OpResponse, error) {
+	var err error
+	switch op.t {
+	// TODO: handle other ops
+	case tRange:
+		var resp *pb.RangeResponse
+		resp, err = kv.remote.Range(ctx, op.toRangeRequest(), grpc.FailFast(false))
+		if err == nil {
+			return OpResponse{get: (*GetResponse)(resp)}, nil
+		}
+	case tPut:
+		var resp *pb.PutResponse
+		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID), PrevKv: op.prevKV, IgnoreValue: op.ignoreValue, IgnoreLease: op.ignoreLease}
+		resp, err = kv.remote.Put(ctx, r)
+		if err == nil {
+			return OpResponse{put: (*PutResponse)(resp)}, nil
+		}
+	case tDeleteRange:
+		var resp *pb.DeleteRangeResponse
+		r := &pb.DeleteRangeRequest{Key: op.key, RangeEnd: op.end, PrevKv: op.prevKV}
+		resp, err = kv.remote.DeleteRange(ctx, r)
+		if err == nil {
+			return OpResponse{del: (*DeleteResponse)(resp)}, nil
+		}
+	default:
+		panic("Unknown op")
+	}
+	return OpResponse{}, err
+}

vendor/github.com/coreos/etcd/clientv3/lease.go

@@ -0,0 +1,547 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"sync"
+	"time"
+
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+type (
+	LeaseRevokeResponse pb.LeaseRevokeResponse
+	LeaseID             int64
+)
+
+// LeaseGrantResponse is used to convert the protobuf grant response.
+type LeaseGrantResponse struct {
+	*pb.ResponseHeader
+	ID    LeaseID
+	TTL   int64
+	Error string
+}
+
+// LeaseKeepAliveResponse is used to convert the protobuf keepalive response.
+type LeaseKeepAliveResponse struct {
+	*pb.ResponseHeader
+	ID  LeaseID
+	TTL int64
+}
+
+// LeaseTimeToLiveResponse is used to convert the protobuf lease timetolive response.
+type LeaseTimeToLiveResponse struct {
+	*pb.ResponseHeader
+	ID LeaseID `json:"id"`
+
+	// TTL is the remaining TTL in seconds for the lease; the lease will expire in under TTL+1 seconds.
+	TTL int64 `json:"ttl"`
+
+	// GrantedTTL is the initial granted time in seconds upon lease creation/renewal.
+	GrantedTTL int64 `json:"granted-ttl"`
+
+	// Keys is the list of keys attached to this lease.
+	Keys [][]byte `json:"keys"`
+}
+
+const (
+	// defaultTTL is the assumed lease TTL used for the first keepalive
+	// deadline before the actual TTL is known to the client.
+	defaultTTL = 5 * time.Second
+	// a small buffer to store unsent lease responses.
+	leaseResponseChSize = 16
+	// NoLease is a lease ID for the absence of a lease.
+	NoLease LeaseID = 0
+
+	// retryConnWait is how long to wait before retrying request due to an error
+	retryConnWait = 500 * time.Millisecond
+)
+
+// ErrKeepAliveHalted is returned if client keep alive loop halts with an unexpected error.
+//
+// This usually means that automatic lease renewal via KeepAlive is broken, but KeepAliveOnce will still work as expected.
+type ErrKeepAliveHalted struct {
+	Reason error
+}
+
+func (e ErrKeepAliveHalted) Error() string {
+	s := "etcdclient: leases keep alive halted"
+	if e.Reason != nil {
+		s += ": " + e.Reason.Error()
+	}
+	return s
+}
+
+type Lease interface {
+	// Grant creates a new lease.
+	Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error)
+
+	// Revoke revokes the given lease.
+	Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error)
+
+	// TimeToLive retrieves the lease information of the given lease ID.
+	TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error)
+
+	// KeepAlive keeps the given lease alive forever.
+	KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error)
+
+	// KeepAliveOnce renews the lease once. In most of the cases, Keepalive
+	// should be used instead of KeepAliveOnce.
+	KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error)
+
+	// Close releases all resources Lease keeps for efficient communication
+	// with the etcd server.
+	Close() error
+}
+
+type lessor struct {
+	mu sync.Mutex // guards all fields
+
+	// donec is closed and loopErr is set when recvKeepAliveLoop stops
+	donec   chan struct{}
+	loopErr error
+
+	remote pb.LeaseClient
+
+	stream       pb.Lease_LeaseKeepAliveClient
+	streamCancel context.CancelFunc
+
+	stopCtx    context.Context
+	stopCancel context.CancelFunc
+
+	keepAlives map[LeaseID]*keepAlive
+
+	// firstKeepAliveTimeout is the timeout for the first keepalive request
+	// before the actual TTL is known to the lease client
+	firstKeepAliveTimeout time.Duration
+
+	// firstKeepAliveOnce ensures stream starts after first KeepAlive call.
+	firstKeepAliveOnce sync.Once
+}
+
+// keepAlive multiplexes a keepalive for a lease over multiple channels
+type keepAlive struct {
+	chs  []chan<- *LeaseKeepAliveResponse
+	ctxs []context.Context
+	// deadline is the time the keep alive channels close if no response
+	deadline time.Time
+	// nextKeepAlive is when to send the next keep alive message
+	nextKeepAlive time.Time
+	// donec is closed on lease revoke, expiration, or cancel.
+	donec chan struct{}
+}
+
+func NewLease(c *Client) Lease {
+	return NewLeaseFromLeaseClient(RetryLeaseClient(c), c.cfg.DialTimeout+time.Second)
+}
+
+func NewLeaseFromLeaseClient(remote pb.LeaseClient, keepAliveTimeout time.Duration) Lease {
+	l := &lessor{
+		donec:                 make(chan struct{}),
+		keepAlives:            make(map[LeaseID]*keepAlive),
+		remote:                remote,
+		firstKeepAliveTimeout: keepAliveTimeout,
+	}
+	if l.firstKeepAliveTimeout == time.Second {
+		l.firstKeepAliveTimeout = defaultTTL
+	}
+	reqLeaderCtx := WithRequireLeader(context.Background())
+	l.stopCtx, l.stopCancel = context.WithCancel(reqLeaderCtx)
+	return l
+}
+
+func (l *lessor) Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error) {
+	for {
+		r := &pb.LeaseGrantRequest{TTL: ttl}
+		resp, err := l.remote.LeaseGrant(ctx, r)
+		if err == nil {
+			gresp := &LeaseGrantResponse{
+				ResponseHeader: resp.GetHeader(),
+				ID:             LeaseID(resp.ID),
+				TTL:            resp.TTL,
+				Error:          resp.Error,
+			}
+			return gresp, nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (l *lessor) Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error) {
+	for {
+		r := &pb.LeaseRevokeRequest{ID: int64(id)}
+		resp, err := l.remote.LeaseRevoke(ctx, r)
+
+		if err == nil {
+			return (*LeaseRevokeResponse)(resp), nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (l *lessor) TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error) {
+	for {
+		r := toLeaseTimeToLiveRequest(id, opts...)
+		resp, err := l.remote.LeaseTimeToLive(ctx, r, grpc.FailFast(false))
+		if err == nil {
+			gresp := &LeaseTimeToLiveResponse{
+				ResponseHeader: resp.GetHeader(),
+				ID:             LeaseID(resp.ID),
+				TTL:            resp.TTL,
+				GrantedTTL:     resp.GrantedTTL,
+				Keys:           resp.Keys,
+			}
+			return gresp, nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (l *lessor) KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error) {
+	ch := make(chan *LeaseKeepAliveResponse, leaseResponseChSize)
+
+	l.mu.Lock()
+	// ensure that recvKeepAliveLoop is still running
+	select {
+	case <-l.donec:
+		err := l.loopErr
+		l.mu.Unlock()
+		close(ch)
+		return ch, ErrKeepAliveHalted{Reason: err}
+	default:
+	}
+	ka, ok := l.keepAlives[id]
+	if !ok {
+		// create fresh keep alive
+		ka = &keepAlive{
+			chs:           []chan<- *LeaseKeepAliveResponse{ch},
+			ctxs:          []context.Context{ctx},
+			deadline:      time.Now().Add(l.firstKeepAliveTimeout),
+			nextKeepAlive: time.Now(),
+			donec:         make(chan struct{}),
+		}
+		l.keepAlives[id] = ka
+	} else {
+		// add channel and context to existing keep alive
+		ka.ctxs = append(ka.ctxs, ctx)
+		ka.chs = append(ka.chs, ch)
+	}
+	l.mu.Unlock()
+
+	go l.keepAliveCtxCloser(id, ctx, ka.donec)
+	l.firstKeepAliveOnce.Do(func() {
+		go l.recvKeepAliveLoop()
+		go l.deadlineLoop()
+	})
+
+	return ch, nil
+}
+
+func (l *lessor) KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
+	for {
+		resp, err := l.keepAliveOnce(ctx, id)
+		if err == nil {
+			if resp.TTL <= 0 {
+				err = rpctypes.ErrLeaseNotFound
+			}
+			return resp, err
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (l *lessor) Close() error {
+	l.stopCancel()
+	// close for synchronous teardown if stream goroutines never launched
+	l.firstKeepAliveOnce.Do(func() { close(l.donec) })
+	<-l.donec
+	return nil
+}
+
+func (l *lessor) keepAliveCtxCloser(id LeaseID, ctx context.Context, donec <-chan struct{}) {
+	select {
+	case <-donec:
+		return
+	case <-l.donec:
+		return
+	case <-ctx.Done():
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	ka, ok := l.keepAlives[id]
+	if !ok {
+		return
+	}
+
+	// close channel and remove context if still associated with keep alive
+	for i, c := range ka.ctxs {
+		if c == ctx {
+			close(ka.chs[i])
+			ka.ctxs = append(ka.ctxs[:i], ka.ctxs[i+1:]...)
+			ka.chs = append(ka.chs[:i], ka.chs[i+1:]...)
+			break
+		}
+	}
+	// remove if no one more listeners
+	if len(ka.chs) == 0 {
+		delete(l.keepAlives, id)
+	}
+}
+
+// closeRequireLeader scans all keep alives for ctxs that have require leader
+// and closes the associated channels.
+func (l *lessor) closeRequireLeader() {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	for _, ka := range l.keepAlives {
+		reqIdxs := 0
+		// find all required leader channels, close, mark as nil
+		for i, ctx := range ka.ctxs {
+			md, ok := metadata.FromContext(ctx)
+			if !ok {
+				continue
+			}
+			ks := md[rpctypes.MetadataRequireLeaderKey]
+			if len(ks) < 1 || ks[0] != rpctypes.MetadataHasLeader {
+				continue
+			}
+			close(ka.chs[i])
+			ka.chs[i] = nil
+			reqIdxs++
+		}
+		if reqIdxs == 0 {
+			continue
+		}
+		// remove all channels that required a leader from keepalive
+		newChs := make([]chan<- *LeaseKeepAliveResponse, len(ka.chs)-reqIdxs)
+		newCtxs := make([]context.Context, len(newChs))
+		newIdx := 0
+		for i := range ka.chs {
+			if ka.chs[i] == nil {
+				continue
+			}
+			newChs[newIdx], newCtxs[newIdx] = ka.chs[i], ka.ctxs[newIdx]
+			newIdx++
+		}
+		ka.chs, ka.ctxs = newChs, newCtxs
+	}
+}
+
+func (l *lessor) keepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
+	cctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	stream, err := l.remote.LeaseKeepAlive(cctx, grpc.FailFast(false))
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+
+	err = stream.Send(&pb.LeaseKeepAliveRequest{ID: int64(id)})
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+
+	resp, rerr := stream.Recv()
+	if rerr != nil {
+		return nil, toErr(ctx, rerr)
+	}
+
+	karesp := &LeaseKeepAliveResponse{
+		ResponseHeader: resp.GetHeader(),
+		ID:             LeaseID(resp.ID),
+		TTL:            resp.TTL,
+	}
+	return karesp, nil
+}
+
+func (l *lessor) recvKeepAliveLoop() (gerr error) {
+	defer func() {
+		l.mu.Lock()
+		close(l.donec)
+		l.loopErr = gerr
+		for _, ka := range l.keepAlives {
+			ka.Close()
+		}
+		l.keepAlives = make(map[LeaseID]*keepAlive)
+		l.mu.Unlock()
+	}()
+
+	for {
+		stream, err := l.resetRecv()
+		if err != nil {
+			if canceledByCaller(l.stopCtx, err) {
+				return err
+			}
+		} else {
+			for {
+				resp, err := stream.Recv()
+
+				if err != nil {
+					if canceledByCaller(l.stopCtx, err) {
+						return err
+					}
+
+					if toErr(l.stopCtx, err) == rpctypes.ErrNoLeader {
+						l.closeRequireLeader()
+					}
+					break
+				}
+
+				l.recvKeepAlive(resp)
+			}
+		}
+
+		select {
+		case <-time.After(retryConnWait):
+			continue
+		case <-l.stopCtx.Done():
+			return l.stopCtx.Err()
+		}
+	}
+}
+
+// resetRecv opens a new lease stream and starts sending LeaseKeepAliveRequests
+func (l *lessor) resetRecv() (pb.Lease_LeaseKeepAliveClient, error) {
+	sctx, cancel := context.WithCancel(l.stopCtx)
+	stream, err := l.remote.LeaseKeepAlive(sctx, grpc.FailFast(false))
+	if err != nil {
+		cancel()
+		return nil, err
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if l.stream != nil && l.streamCancel != nil {
+		l.streamCancel()
+	}
+
+	l.streamCancel = cancel
+	l.stream = stream
+
+	go l.sendKeepAliveLoop(stream)
+	return stream, nil
+}
+
+// recvKeepAlive updates a lease based on its LeaseKeepAliveResponse
+func (l *lessor) recvKeepAlive(resp *pb.LeaseKeepAliveResponse) {
+	karesp := &LeaseKeepAliveResponse{
+		ResponseHeader: resp.GetHeader(),
+		ID:             LeaseID(resp.ID),
+		TTL:            resp.TTL,
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	ka, ok := l.keepAlives[karesp.ID]
+	if !ok {
+		return
+	}
+
+	if karesp.TTL <= 0 {
+		// lease expired; close all keep alive channels
+		delete(l.keepAlives, karesp.ID)
+		ka.Close()
+		return
+	}
+
+	// send update to all channels
+	nextKeepAlive := time.Now().Add((time.Duration(karesp.TTL) * time.Second) / 3.0)
+	ka.deadline = time.Now().Add(time.Duration(karesp.TTL) * time.Second)
+	for _, ch := range ka.chs {
+		select {
+		case ch <- karesp:
+			ka.nextKeepAlive = nextKeepAlive
+		default:
+		}
+	}
+}
+
+// deadlineLoop reaps any keep alive channels that have not received a response
+// within the lease TTL
+func (l *lessor) deadlineLoop() {
+	for {
+		select {
+		case <-time.After(time.Second):
+		case <-l.donec:
+			return
+		}
+		now := time.Now()
+		l.mu.Lock()
+		for id, ka := range l.keepAlives {
+			if ka.deadline.Before(now) {
+				// waited too long for response; lease may be expired
+				ka.Close()
+				delete(l.keepAlives, id)
+			}
+		}
+		l.mu.Unlock()
+	}
+}
+
+// sendKeepAliveLoop sends LeaseKeepAliveRequests for the lifetime of a lease stream
+func (l *lessor) sendKeepAliveLoop(stream pb.Lease_LeaseKeepAliveClient) {
+	for {
+		var tosend []LeaseID
+
+		now := time.Now()
+		l.mu.Lock()
+		for id, ka := range l.keepAlives {
+			if ka.nextKeepAlive.Before(now) {
+				tosend = append(tosend, id)
+			}
+		}
+		l.mu.Unlock()
+
+		for _, id := range tosend {
+			r := &pb.LeaseKeepAliveRequest{ID: int64(id)}
+			if err := stream.Send(r); err != nil {
+				// TODO do something with this error?
+				return
+			}
+		}
+
+		select {
+		case <-time.After(500 * time.Millisecond):
+		case <-stream.Context().Done():
+			return
+		case <-l.donec:
+			return
+		case <-l.stopCtx.Done():
+			return
+		}
+	}
+}
+
+func (ka *keepAlive) Close() {
+	close(ka.donec)
+	for _, ch := range ka.chs {
+		close(ch)
+	}
+}

vendor/github.com/coreos/etcd/clientv3/logger.go

@@ -0,0 +1,82 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"io/ioutil"
+	"log"
+	"sync"
+
+	"google.golang.org/grpc/grpclog"
+)
+
+// Logger is the logger used by client library.
+// It implements grpclog.Logger interface.
+type Logger grpclog.Logger
+
+var (
+	logger settableLogger
+)
+
+type settableLogger struct {
+	l  grpclog.Logger
+	mu sync.RWMutex
+}
+
+func init() {
+	// disable client side logs by default
+	logger.mu.Lock()
+	logger.l = log.New(ioutil.Discard, "", 0)
+
+	// logger has to override the grpclog at initialization so that
+	// any changes to the grpclog go through logger with locking
+	// instead of through SetLogger
+	//
+	// now updates only happen through settableLogger.set
+	grpclog.SetLogger(&logger)
+	logger.mu.Unlock()
+}
+
+// SetLogger sets client-side Logger. By default, logs are disabled.
+func SetLogger(l Logger) {
+	logger.set(l)
+}
+
+// GetLogger returns the current logger.
+func GetLogger() Logger {
+	return logger.get()
+}
+
+func (s *settableLogger) set(l Logger) {
+	s.mu.Lock()
+	logger.l = l
+	s.mu.Unlock()
+}
+
+func (s *settableLogger) get() Logger {
+	s.mu.RLock()
+	l := logger.l
+	s.mu.RUnlock()
+	return l
+}
+
+// implement the grpclog.Logger interface
+
+func (s *settableLogger) Fatal(args ...interface{})                 { s.get().Fatal(args...) }
+func (s *settableLogger) Fatalf(format string, args ...interface{}) { s.get().Fatalf(format, args...) }
+func (s *settableLogger) Fatalln(args ...interface{})               { s.get().Fatalln(args...) }
+func (s *settableLogger) Print(args ...interface{})                 { s.get().Print(args...) }
+func (s *settableLogger) Printf(format string, args ...interface{}) { s.get().Printf(format, args...) }
+func (s *settableLogger) Println(args ...interface{})               { s.get().Println(args...) }

vendor/github.com/coreos/etcd/clientv3/maintenance.go

@@ -0,0 +1,182 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"io"
+
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+type (
+	DefragmentResponse pb.DefragmentResponse
+	AlarmResponse      pb.AlarmResponse
+	AlarmMember        pb.AlarmMember
+	StatusResponse     pb.StatusResponse
+)
+
+type Maintenance interface {
+	// AlarmList gets all active alarms.
+	AlarmList(ctx context.Context) (*AlarmResponse, error)
+
+	// AlarmDisarm disarms a given alarm.
+	AlarmDisarm(ctx context.Context, m *AlarmMember) (*AlarmResponse, error)
+
+	// Defragment defragments storage backend of the etcd member with given endpoint.
+	// Defragment is only needed when deleting a large number of keys and want to reclaim
+	// the resources.
+	// Defragment is an expensive operation. User should avoid defragmenting multiple members
+	// at the same time.
+	// To defragment multiple members in the cluster, user need to call defragment multiple
+	// times with different endpoints.
+	Defragment(ctx context.Context, endpoint string) (*DefragmentResponse, error)
+
+	// Status gets the status of the endpoint.
+	Status(ctx context.Context, endpoint string) (*StatusResponse, error)
+
+	// Snapshot provides a reader for a snapshot of a backend.
+	Snapshot(ctx context.Context) (io.ReadCloser, error)
+}
+
+type maintenance struct {
+	dial   func(endpoint string) (pb.MaintenanceClient, func(), error)
+	remote pb.MaintenanceClient
+}
+
+func NewMaintenance(c *Client) Maintenance {
+	return &maintenance{
+		dial: func(endpoint string) (pb.MaintenanceClient, func(), error) {
+			conn, err := c.dial(endpoint)
+			if err != nil {
+				return nil, nil, err
+			}
+			cancel := func() { conn.Close() }
+			return pb.NewMaintenanceClient(conn), cancel, nil
+		},
+		remote: pb.NewMaintenanceClient(c.conn),
+	}
+}
+
+func NewMaintenanceFromMaintenanceClient(remote pb.MaintenanceClient) Maintenance {
+	return &maintenance{
+		dial: func(string) (pb.MaintenanceClient, func(), error) {
+			return remote, func() {}, nil
+		},
+		remote: remote,
+	}
+}
+
+func (m *maintenance) AlarmList(ctx context.Context) (*AlarmResponse, error) {
+	req := &pb.AlarmRequest{
+		Action:   pb.AlarmRequest_GET,
+		MemberID: 0,                 // all
+		Alarm:    pb.AlarmType_NONE, // all
+	}
+	for {
+		resp, err := m.remote.Alarm(ctx, req, grpc.FailFast(false))
+		if err == nil {
+			return (*AlarmResponse)(resp), nil
+		}
+		if isHaltErr(ctx, err) {
+			return nil, toErr(ctx, err)
+		}
+	}
+}
+
+func (m *maintenance) AlarmDisarm(ctx context.Context, am *AlarmMember) (*AlarmResponse, error) {
+	req := &pb.AlarmRequest{
+		Action:   pb.AlarmRequest_DEACTIVATE,
+		MemberID: am.MemberID,
+		Alarm:    am.Alarm,
+	}
+
+	if req.MemberID == 0 && req.Alarm == pb.AlarmType_NONE {
+		ar, err := m.AlarmList(ctx)
+		if err != nil {
+			return nil, toErr(ctx, err)
+		}
+		ret := AlarmResponse{}
+		for _, am := range ar.Alarms {
+			dresp, derr := m.AlarmDisarm(ctx, (*AlarmMember)(am))
+			if derr != nil {
+				return nil, toErr(ctx, derr)
+			}
+			ret.Alarms = append(ret.Alarms, dresp.Alarms...)
+		}
+		return &ret, nil
+	}
+
+	resp, err := m.remote.Alarm(ctx, req, grpc.FailFast(false))
+	if err == nil {
+		return (*AlarmResponse)(resp), nil
+	}
+	return nil, toErr(ctx, err)
+}
+
+func (m *maintenance) Defragment(ctx context.Context, endpoint string) (*DefragmentResponse, error) {
+	remote, cancel, err := m.dial(endpoint)
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	defer cancel()
+	resp, err := remote.Defragment(ctx, &pb.DefragmentRequest{}, grpc.FailFast(false))
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	return (*DefragmentResponse)(resp), nil
+}
+
+func (m *maintenance) Status(ctx context.Context, endpoint string) (*StatusResponse, error) {
+	remote, cancel, err := m.dial(endpoint)
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	defer cancel()
+	resp, err := remote.Status(ctx, &pb.StatusRequest{}, grpc.FailFast(false))
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+	return (*StatusResponse)(resp), nil
+}
+
+func (m *maintenance) Snapshot(ctx context.Context) (io.ReadCloser, error) {
+	ss, err := m.remote.Snapshot(ctx, &pb.SnapshotRequest{}, grpc.FailFast(false))
+	if err != nil {
+		return nil, toErr(ctx, err)
+	}
+
+	pr, pw := io.Pipe()
+	go func() {
+		for {
+			resp, err := ss.Recv()
+			if err != nil {
+				pw.CloseWithError(err)
+				return
+			}
+			if resp == nil && err == nil {
+				break
+			}
+			if _, werr := pw.Write(resp.Blob); werr != nil {
+				pw.CloseWithError(werr)
+				return
+			}
+		}
+		pw.Close()
+	}()
+	return pr, nil
+}

vendor/github.com/coreos/etcd/clientv3/op.go

@@ -0,0 +1,437 @@
+// Copyright 2016 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 clientv3
+
+import pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+
+type opType int
+
+const (
+	// A default Op has opType 0, which is invalid.
+	tRange opType = iota + 1
+	tPut
+	tDeleteRange
+)
+
+var (
+	noPrefixEnd = []byte{0}
+)
+
+// Op represents an Operation that kv can execute.
+type Op struct {
+	t   opType
+	key []byte
+	end []byte
+
+	// for range
+	limit        int64
+	sort         *SortOption
+	serializable bool
+	keysOnly     bool
+	countOnly    bool
+	minModRev    int64
+	maxModRev    int64
+	minCreateRev int64
+	maxCreateRev int64
+
+	// for range, watch
+	rev int64
+
+	// for watch, put, delete
+	prevKV bool
+
+	// for put
+	ignoreValue bool
+	ignoreLease bool
+
+	// progressNotify is for progress updates.
+	progressNotify bool
+	// createdNotify is for created event
+	createdNotify bool
+	// filters for watchers
+	filterPut    bool
+	filterDelete bool
+
+	// for put
+	val     []byte
+	leaseID LeaseID
+}
+
+// accesors / mutators
+
+// KeyBytes returns the byte slice holding the Op's key.
+func (op Op) KeyBytes() []byte { return op.key }
+
+// WithKeyBytes sets the byte slice for the Op's key.
+func (op *Op) WithKeyBytes(key []byte) { op.key = key }
+
+// RangeBytes returns the byte slice holding with the Op's range end, if any.
+func (op Op) RangeBytes() []byte { return op.end }
+
+// WithRangeBytes sets the byte slice for the Op's range end.
+func (op *Op) WithRangeBytes(end []byte) { op.end = end }
+
+// ValueBytes returns the byte slice holding the Op's value, if any.
+func (op Op) ValueBytes() []byte { return op.val }
+
+// WithValueBytes sets the byte slice for the Op's value.
+func (op *Op) WithValueBytes(v []byte) { op.val = v }
+
+func (op Op) toRangeRequest() *pb.RangeRequest {
+	if op.t != tRange {
+		panic("op.t != tRange")
+	}
+	r := &pb.RangeRequest{
+		Key:               op.key,
+		RangeEnd:          op.end,
+		Limit:             op.limit,
+		Revision:          op.rev,
+		Serializable:      op.serializable,
+		KeysOnly:          op.keysOnly,
+		CountOnly:         op.countOnly,
+		MinModRevision:    op.minModRev,
+		MaxModRevision:    op.maxModRev,
+		MinCreateRevision: op.minCreateRev,
+		MaxCreateRevision: op.maxCreateRev,
+	}
+	if op.sort != nil {
+		r.SortOrder = pb.RangeRequest_SortOrder(op.sort.Order)
+		r.SortTarget = pb.RangeRequest_SortTarget(op.sort.Target)
+	}
+	return r
+}
+
+func (op Op) toRequestOp() *pb.RequestOp {
+	switch op.t {
+	case tRange:
+		return &pb.RequestOp{Request: &pb.RequestOp_RequestRange{RequestRange: op.toRangeRequest()}}
+	case tPut:
+		r := &pb.PutRequest{Key: op.key, Value: op.val, Lease: int64(op.leaseID), PrevKv: op.prevKV, IgnoreValue: op.ignoreValue, IgnoreLease: op.ignoreLease}
+		return &pb.RequestOp{Request: &pb.RequestOp_RequestPut{RequestPut: r}}
+	case tDeleteRange:
+		r := &pb.DeleteRangeRequest{Key: op.key, RangeEnd: op.end, PrevKv: op.prevKV}
+		return &pb.RequestOp{Request: &pb.RequestOp_RequestDeleteRange{RequestDeleteRange: r}}
+	default:
+		panic("Unknown Op")
+	}
+}
+
+func (op Op) isWrite() bool {
+	return op.t != tRange
+}
+
+func OpGet(key string, opts ...OpOption) Op {
+	ret := Op{t: tRange, key: []byte(key)}
+	ret.applyOpts(opts)
+	return ret
+}
+
+func OpDelete(key string, opts ...OpOption) Op {
+	ret := Op{t: tDeleteRange, key: []byte(key)}
+	ret.applyOpts(opts)
+	switch {
+	case ret.leaseID != 0:
+		panic("unexpected lease in delete")
+	case ret.limit != 0:
+		panic("unexpected limit in delete")
+	case ret.rev != 0:
+		panic("unexpected revision in delete")
+	case ret.sort != nil:
+		panic("unexpected sort in delete")
+	case ret.serializable:
+		panic("unexpected serializable in delete")
+	case ret.countOnly:
+		panic("unexpected countOnly in delete")
+	case ret.minModRev != 0, ret.maxModRev != 0:
+		panic("unexpected mod revision filter in delete")
+	case ret.minCreateRev != 0, ret.maxCreateRev != 0:
+		panic("unexpected create revision filter in delete")
+	case ret.filterDelete, ret.filterPut:
+		panic("unexpected filter in delete")
+	case ret.createdNotify:
+		panic("unexpected createdNotify in delete")
+	}
+	return ret
+}
+
+func OpPut(key, val string, opts ...OpOption) Op {
+	ret := Op{t: tPut, key: []byte(key), val: []byte(val)}
+	ret.applyOpts(opts)
+	switch {
+	case ret.end != nil:
+		panic("unexpected range in put")
+	case ret.limit != 0:
+		panic("unexpected limit in put")
+	case ret.rev != 0:
+		panic("unexpected revision in put")
+	case ret.sort != nil:
+		panic("unexpected sort in put")
+	case ret.serializable:
+		panic("unexpected serializable in put")
+	case ret.countOnly:
+		panic("unexpected countOnly in put")
+	case ret.minModRev != 0, ret.maxModRev != 0:
+		panic("unexpected mod revision filter in put")
+	case ret.minCreateRev != 0, ret.maxCreateRev != 0:
+		panic("unexpected create revision filter in put")
+	case ret.filterDelete, ret.filterPut:
+		panic("unexpected filter in put")
+	case ret.createdNotify:
+		panic("unexpected createdNotify in put")
+	}
+	return ret
+}
+
+func opWatch(key string, opts ...OpOption) Op {
+	ret := Op{t: tRange, key: []byte(key)}
+	ret.applyOpts(opts)
+	switch {
+	case ret.leaseID != 0:
+		panic("unexpected lease in watch")
+	case ret.limit != 0:
+		panic("unexpected limit in watch")
+	case ret.sort != nil:
+		panic("unexpected sort in watch")
+	case ret.serializable:
+		panic("unexpected serializable in watch")
+	case ret.countOnly:
+		panic("unexpected countOnly in watch")
+	case ret.minModRev != 0, ret.maxModRev != 0:
+		panic("unexpected mod revision filter in watch")
+	case ret.minCreateRev != 0, ret.maxCreateRev != 0:
+		panic("unexpected create revision filter in watch")
+	}
+	return ret
+}
+
+func (op *Op) applyOpts(opts []OpOption) {
+	for _, opt := range opts {
+		opt(op)
+	}
+}
+
+// OpOption configures Operations like Get, Put, Delete.
+type OpOption func(*Op)
+
+// WithLease attaches a lease ID to a key in 'Put' request.
+func WithLease(leaseID LeaseID) OpOption {
+	return func(op *Op) { op.leaseID = leaseID }
+}
+
+// WithLimit limits the number of results to return from 'Get' request.
+// If WithLimit is given a 0 limit, it is treated as no limit.
+func WithLimit(n int64) OpOption { return func(op *Op) { op.limit = n } }
+
+// WithRev specifies the store revision for 'Get' request.
+// Or the start revision of 'Watch' request.
+func WithRev(rev int64) OpOption { return func(op *Op) { op.rev = rev } }
+
+// WithSort specifies the ordering in 'Get' request. It requires
+// 'WithRange' and/or 'WithPrefix' to be specified too.
+// 'target' specifies the target to sort by: key, version, revisions, value.
+// 'order' can be either 'SortNone', 'SortAscend', 'SortDescend'.
+func WithSort(target SortTarget, order SortOrder) OpOption {
+	return func(op *Op) {
+		if target == SortByKey && order == SortAscend {
+			// If order != SortNone, server fetches the entire key-space,
+			// and then applies the sort and limit, if provided.
+			// Since current mvcc.Range implementation returns results
+			// sorted by keys in lexicographically ascending order,
+			// client should ignore SortOrder if the target is SortByKey.
+			order = SortNone
+		}
+		op.sort = &SortOption{target, order}
+	}
+}
+
+// GetPrefixRangeEnd gets the range end of the prefix.
+// 'Get(foo, WithPrefix())' is equal to 'Get(foo, WithRange(GetPrefixRangeEnd(foo))'.
+func GetPrefixRangeEnd(prefix string) string {
+	return string(getPrefix([]byte(prefix)))
+}
+
+func getPrefix(key []byte) []byte {
+	end := make([]byte, len(key))
+	copy(end, key)
+	for i := len(end) - 1; i >= 0; i-- {
+		if end[i] < 0xff {
+			end[i] = end[i] + 1
+			end = end[:i+1]
+			return end
+		}
+	}
+	// next prefix does not exist (e.g., 0xffff);
+	// default to WithFromKey policy
+	return noPrefixEnd
+}
+
+// WithPrefix enables 'Get', 'Delete', or 'Watch' requests to operate
+// on the keys with matching prefix. For example, 'Get(foo, WithPrefix())'
+// can return 'foo1', 'foo2', and so on.
+func WithPrefix() OpOption {
+	return func(op *Op) {
+		if len(op.key) == 0 {
+			op.key, op.end = []byte{0}, []byte{0}
+			return
+		}
+		op.end = getPrefix(op.key)
+	}
+}
+
+// WithRange specifies the range of 'Get', 'Delete', 'Watch' requests.
+// For example, 'Get' requests with 'WithRange(end)' returns
+// the keys in the range [key, end).
+// endKey must be lexicographically greater than start key.
+func WithRange(endKey string) OpOption {
+	return func(op *Op) { op.end = []byte(endKey) }
+}
+
+// WithFromKey specifies the range of 'Get', 'Delete', 'Watch' requests
+// to be equal or greater than the key in the argument.
+func WithFromKey() OpOption { return WithRange("\x00") }
+
+// WithSerializable makes 'Get' request serializable. By default,
+// it's linearizable. Serializable requests are better for lower latency
+// requirement.
+func WithSerializable() OpOption {
+	return func(op *Op) { op.serializable = true }
+}
+
+// WithKeysOnly makes the 'Get' request return only the keys and the corresponding
+// values will be omitted.
+func WithKeysOnly() OpOption {
+	return func(op *Op) { op.keysOnly = true }
+}
+
+// WithCountOnly makes the 'Get' request return only the count of keys.
+func WithCountOnly() OpOption {
+	return func(op *Op) { op.countOnly = true }
+}
+
+// WithMinModRev filters out keys for Get with modification revisions less than the given revision.
+func WithMinModRev(rev int64) OpOption { return func(op *Op) { op.minModRev = rev } }
+
+// WithMaxModRev filters out keys for Get with modification revisions greater than the given revision.
+func WithMaxModRev(rev int64) OpOption { return func(op *Op) { op.maxModRev = rev } }
+
+// WithMinCreateRev filters out keys for Get with creation revisions less than the given revision.
+func WithMinCreateRev(rev int64) OpOption { return func(op *Op) { op.minCreateRev = rev } }
+
+// WithMaxCreateRev filters out keys for Get with creation revisions greater than the given revision.
+func WithMaxCreateRev(rev int64) OpOption { return func(op *Op) { op.maxCreateRev = rev } }
+
+// WithFirstCreate gets the key with the oldest creation revision in the request range.
+func WithFirstCreate() []OpOption { return withTop(SortByCreateRevision, SortAscend) }
+
+// WithLastCreate gets the key with the latest creation revision in the request range.
+func WithLastCreate() []OpOption { return withTop(SortByCreateRevision, SortDescend) }
+
+// WithFirstKey gets the lexically first key in the request range.
+func WithFirstKey() []OpOption { return withTop(SortByKey, SortAscend) }
+
+// WithLastKey gets the lexically last key in the request range.
+func WithLastKey() []OpOption { return withTop(SortByKey, SortDescend) }
+
+// WithFirstRev gets the key with the oldest modification revision in the request range.
+func WithFirstRev() []OpOption { return withTop(SortByModRevision, SortAscend) }
+
+// WithLastRev gets the key with the latest modification revision in the request range.
+func WithLastRev() []OpOption { return withTop(SortByModRevision, SortDescend) }
+
+// withTop gets the first key over the get's prefix given a sort order
+func withTop(target SortTarget, order SortOrder) []OpOption {
+	return []OpOption{WithPrefix(), WithSort(target, order), WithLimit(1)}
+}
+
+// WithProgressNotify makes watch server send periodic progress updates
+// every 10 minutes when there is no incoming events.
+// Progress updates have zero events in WatchResponse.
+func WithProgressNotify() OpOption {
+	return func(op *Op) {
+		op.progressNotify = true
+	}
+}
+
+// WithCreatedNotify makes watch server sends the created event.
+func WithCreatedNotify() OpOption {
+	return func(op *Op) {
+		op.createdNotify = true
+	}
+}
+
+// WithFilterPut discards PUT events from the watcher.
+func WithFilterPut() OpOption {
+	return func(op *Op) { op.filterPut = true }
+}
+
+// WithFilterDelete discards DELETE events from the watcher.
+func WithFilterDelete() OpOption {
+	return func(op *Op) { op.filterDelete = true }
+}
+
+// WithPrevKV gets the previous key-value pair before the event happens. If the previous KV is already compacted,
+// nothing will be returned.
+func WithPrevKV() OpOption {
+	return func(op *Op) {
+		op.prevKV = true
+	}
+}
+
+// WithIgnoreValue updates the key using its current value.
+// Empty value should be passed when ignore_value is set.
+// Returns an error if the key does not exist.
+func WithIgnoreValue() OpOption {
+	return func(op *Op) {
+		op.ignoreValue = true
+	}
+}
+
+// WithIgnoreLease updates the key using its current lease.
+// Empty lease should be passed when ignore_lease is set.
+// Returns an error if the key does not exist.
+func WithIgnoreLease() OpOption {
+	return func(op *Op) {
+		op.ignoreLease = true
+	}
+}
+
+// LeaseOp represents an Operation that lease can execute.
+type LeaseOp struct {
+	id LeaseID
+
+	// for TimeToLive
+	attachedKeys bool
+}
+
+// LeaseOption configures lease operations.
+type LeaseOption func(*LeaseOp)
+
+func (op *LeaseOp) applyOpts(opts []LeaseOption) {
+	for _, opt := range opts {
+		opt(op)
+	}
+}
+
+// WithAttachedKeys requests lease timetolive API to return
+// attached keys of given lease ID.
+func WithAttachedKeys() LeaseOption {
+	return func(op *LeaseOp) { op.attachedKeys = true }
+}
+
+func toLeaseTimeToLiveRequest(id LeaseID, opts ...LeaseOption) *pb.LeaseTimeToLiveRequest {
+	ret := &LeaseOp{id: id}
+	ret.applyOpts(opts)
+	return &pb.LeaseTimeToLiveRequest{ID: int64(id), Keys: ret.attachedKeys}
+}

vendor/github.com/coreos/etcd/clientv3/retry.go

@@ -0,0 +1,293 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+type rpcFunc func(ctx context.Context) error
+type retryRpcFunc func(context.Context, rpcFunc) error
+
+func (c *Client) newRetryWrapper() retryRpcFunc {
+	return func(rpcCtx context.Context, f rpcFunc) error {
+		for {
+			err := f(rpcCtx)
+			if err == nil {
+				return nil
+			}
+
+			eErr := rpctypes.Error(err)
+			// always stop retry on etcd errors
+			if _, ok := eErr.(rpctypes.EtcdError); ok {
+				return err
+			}
+
+			// only retry if unavailable
+			if grpc.Code(err) != codes.Unavailable {
+				return err
+			}
+
+			select {
+			case <-c.balancer.ConnectNotify():
+			case <-rpcCtx.Done():
+				return rpcCtx.Err()
+			case <-c.ctx.Done():
+				return c.ctx.Err()
+			}
+		}
+	}
+}
+
+func (c *Client) newAuthRetryWrapper() retryRpcFunc {
+	return func(rpcCtx context.Context, f rpcFunc) error {
+		for {
+			err := f(rpcCtx)
+			if err == nil {
+				return nil
+			}
+
+			// always stop retry on etcd errors other than invalid auth token
+			if rpctypes.Error(err) == rpctypes.ErrInvalidAuthToken {
+				gterr := c.getToken(rpcCtx)
+				if gterr != nil {
+					return err // return the original error for simplicity
+				}
+				continue
+			}
+
+			return err
+		}
+	}
+}
+
+// RetryKVClient implements a KVClient that uses the client's FailFast retry policy.
+func RetryKVClient(c *Client) pb.KVClient {
+	retryWrite := &retryWriteKVClient{pb.NewKVClient(c.conn), c.retryWrapper}
+	return &retryKVClient{&retryWriteKVClient{retryWrite, c.retryAuthWrapper}}
+}
+
+type retryKVClient struct {
+	*retryWriteKVClient
+}
+
+func (rkv *retryKVClient) Range(ctx context.Context, in *pb.RangeRequest, opts ...grpc.CallOption) (resp *pb.RangeResponse, err error) {
+	err = rkv.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rkv.retryWriteKVClient.Range(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+type retryWriteKVClient struct {
+	pb.KVClient
+	retryf retryRpcFunc
+}
+
+func (rkv *retryWriteKVClient) Put(ctx context.Context, in *pb.PutRequest, opts ...grpc.CallOption) (resp *pb.PutResponse, err error) {
+	err = rkv.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rkv.KVClient.Put(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rkv *retryWriteKVClient) DeleteRange(ctx context.Context, in *pb.DeleteRangeRequest, opts ...grpc.CallOption) (resp *pb.DeleteRangeResponse, err error) {
+	err = rkv.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rkv.KVClient.DeleteRange(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rkv *retryWriteKVClient) Txn(ctx context.Context, in *pb.TxnRequest, opts ...grpc.CallOption) (resp *pb.TxnResponse, err error) {
+	err = rkv.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rkv.KVClient.Txn(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rkv *retryWriteKVClient) Compact(ctx context.Context, in *pb.CompactionRequest, opts ...grpc.CallOption) (resp *pb.CompactionResponse, err error) {
+	err = rkv.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rkv.KVClient.Compact(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+type retryLeaseClient struct {
+	pb.LeaseClient
+	retryf retryRpcFunc
+}
+
+// RetryLeaseClient implements a LeaseClient that uses the client's FailFast retry policy.
+func RetryLeaseClient(c *Client) pb.LeaseClient {
+	retry := &retryLeaseClient{pb.NewLeaseClient(c.conn), c.retryWrapper}
+	return &retryLeaseClient{retry, c.retryAuthWrapper}
+}
+
+func (rlc *retryLeaseClient) LeaseGrant(ctx context.Context, in *pb.LeaseGrantRequest, opts ...grpc.CallOption) (resp *pb.LeaseGrantResponse, err error) {
+	err = rlc.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rlc.LeaseClient.LeaseGrant(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+
+}
+
+func (rlc *retryLeaseClient) LeaseRevoke(ctx context.Context, in *pb.LeaseRevokeRequest, opts ...grpc.CallOption) (resp *pb.LeaseRevokeResponse, err error) {
+	err = rlc.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rlc.LeaseClient.LeaseRevoke(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+type retryClusterClient struct {
+	pb.ClusterClient
+	retryf retryRpcFunc
+}
+
+// RetryClusterClient implements a ClusterClient that uses the client's FailFast retry policy.
+func RetryClusterClient(c *Client) pb.ClusterClient {
+	return &retryClusterClient{pb.NewClusterClient(c.conn), c.retryWrapper}
+}
+
+func (rcc *retryClusterClient) MemberAdd(ctx context.Context, in *pb.MemberAddRequest, opts ...grpc.CallOption) (resp *pb.MemberAddResponse, err error) {
+	err = rcc.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rcc.ClusterClient.MemberAdd(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rcc *retryClusterClient) MemberRemove(ctx context.Context, in *pb.MemberRemoveRequest, opts ...grpc.CallOption) (resp *pb.MemberRemoveResponse, err error) {
+	err = rcc.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rcc.ClusterClient.MemberRemove(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rcc *retryClusterClient) MemberUpdate(ctx context.Context, in *pb.MemberUpdateRequest, opts ...grpc.CallOption) (resp *pb.MemberUpdateResponse, err error) {
+	err = rcc.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rcc.ClusterClient.MemberUpdate(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+type retryAuthClient struct {
+	pb.AuthClient
+	retryf retryRpcFunc
+}
+
+// RetryAuthClient implements a AuthClient that uses the client's FailFast retry policy.
+func RetryAuthClient(c *Client) pb.AuthClient {
+	return &retryAuthClient{pb.NewAuthClient(c.conn), c.retryWrapper}
+}
+
+func (rac *retryAuthClient) AuthEnable(ctx context.Context, in *pb.AuthEnableRequest, opts ...grpc.CallOption) (resp *pb.AuthEnableResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.AuthEnable(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) AuthDisable(ctx context.Context, in *pb.AuthDisableRequest, opts ...grpc.CallOption) (resp *pb.AuthDisableResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.AuthDisable(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) UserAdd(ctx context.Context, in *pb.AuthUserAddRequest, opts ...grpc.CallOption) (resp *pb.AuthUserAddResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.UserAdd(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) UserDelete(ctx context.Context, in *pb.AuthUserDeleteRequest, opts ...grpc.CallOption) (resp *pb.AuthUserDeleteResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.UserDelete(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) UserChangePassword(ctx context.Context, in *pb.AuthUserChangePasswordRequest, opts ...grpc.CallOption) (resp *pb.AuthUserChangePasswordResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.UserChangePassword(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) UserGrantRole(ctx context.Context, in *pb.AuthUserGrantRoleRequest, opts ...grpc.CallOption) (resp *pb.AuthUserGrantRoleResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.UserGrantRole(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) UserRevokeRole(ctx context.Context, in *pb.AuthUserRevokeRoleRequest, opts ...grpc.CallOption) (resp *pb.AuthUserRevokeRoleResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.UserRevokeRole(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) RoleAdd(ctx context.Context, in *pb.AuthRoleAddRequest, opts ...grpc.CallOption) (resp *pb.AuthRoleAddResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.RoleAdd(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) RoleDelete(ctx context.Context, in *pb.AuthRoleDeleteRequest, opts ...grpc.CallOption) (resp *pb.AuthRoleDeleteResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.RoleDelete(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) RoleGrantPermission(ctx context.Context, in *pb.AuthRoleGrantPermissionRequest, opts ...grpc.CallOption) (resp *pb.AuthRoleGrantPermissionResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.RoleGrantPermission(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}
+
+func (rac *retryAuthClient) RoleRevokePermission(ctx context.Context, in *pb.AuthRoleRevokePermissionRequest, opts ...grpc.CallOption) (resp *pb.AuthRoleRevokePermissionResponse, err error) {
+	err = rac.retryf(ctx, func(rctx context.Context) error {
+		resp, err = rac.AuthClient.RoleRevokePermission(rctx, in, opts...)
+		return err
+	})
+	return resp, err
+}

vendor/github.com/coreos/etcd/clientv3/sort.go

@@ -0,0 +1,37 @@
+// Copyright 2016 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 clientv3
+
+type SortTarget int
+type SortOrder int
+
+const (
+	SortNone SortOrder = iota
+	SortAscend
+	SortDescend
+)
+
+const (
+	SortByKey SortTarget = iota
+	SortByVersion
+	SortByCreateRevision
+	SortByModRevision
+	SortByValue
+)
+
+type SortOption struct {
+	Target SortTarget
+	Order  SortOrder
+}

vendor/github.com/coreos/etcd/clientv3/txn.go

@@ -0,0 +1,164 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"sync"
+
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+// Txn is the interface that wraps mini-transactions.
+//
+//	 Tx.If(
+//	  Compare(Value(k1), ">", v1),
+//	  Compare(Version(k1), "=", 2)
+//	 ).Then(
+//	  OpPut(k2,v2), OpPut(k3,v3)
+//	 ).Else(
+//	  OpPut(k4,v4), OpPut(k5,v5)
+//	 ).Commit()
+//
+type Txn interface {
+	// If takes a list of comparison. If all comparisons passed in succeed,
+	// the operations passed into Then() will be executed. Or the operations
+	// passed into Else() will be executed.
+	If(cs ...Cmp) Txn
+
+	// Then takes a list of operations. The Ops list will be executed, if the
+	// comparisons passed in If() succeed.
+	Then(ops ...Op) Txn
+
+	// Else takes a list of operations. The Ops list will be executed, if the
+	// comparisons passed in If() fail.
+	Else(ops ...Op) Txn
+
+	// Commit tries to commit the transaction.
+	Commit() (*TxnResponse, error)
+}
+
+type txn struct {
+	kv  *kv
+	ctx context.Context
+
+	mu    sync.Mutex
+	cif   bool
+	cthen bool
+	celse bool
+
+	isWrite bool
+
+	cmps []*pb.Compare
+
+	sus []*pb.RequestOp
+	fas []*pb.RequestOp
+}
+
+func (txn *txn) If(cs ...Cmp) Txn {
+	txn.mu.Lock()
+	defer txn.mu.Unlock()
+
+	if txn.cif {
+		panic("cannot call If twice!")
+	}
+
+	if txn.cthen {
+		panic("cannot call If after Then!")
+	}
+
+	if txn.celse {
+		panic("cannot call If after Else!")
+	}
+
+	txn.cif = true
+
+	for i := range cs {
+		txn.cmps = append(txn.cmps, (*pb.Compare)(&cs[i]))
+	}
+
+	return txn
+}
+
+func (txn *txn) Then(ops ...Op) Txn {
+	txn.mu.Lock()
+	defer txn.mu.Unlock()
+
+	if txn.cthen {
+		panic("cannot call Then twice!")
+	}
+	if txn.celse {
+		panic("cannot call Then after Else!")
+	}
+
+	txn.cthen = true
+
+	for _, op := range ops {
+		txn.isWrite = txn.isWrite || op.isWrite()
+		txn.sus = append(txn.sus, op.toRequestOp())
+	}
+
+	return txn
+}
+
+func (txn *txn) Else(ops ...Op) Txn {
+	txn.mu.Lock()
+	defer txn.mu.Unlock()
+
+	if txn.celse {
+		panic("cannot call Else twice!")
+	}
+
+	txn.celse = true
+
+	for _, op := range ops {
+		txn.isWrite = txn.isWrite || op.isWrite()
+		txn.fas = append(txn.fas, op.toRequestOp())
+	}
+
+	return txn
+}
+
+func (txn *txn) Commit() (*TxnResponse, error) {
+	txn.mu.Lock()
+	defer txn.mu.Unlock()
+	for {
+		resp, err := txn.commit()
+		if err == nil {
+			return resp, err
+		}
+		if isHaltErr(txn.ctx, err) {
+			return nil, toErr(txn.ctx, err)
+		}
+		if txn.isWrite {
+			return nil, toErr(txn.ctx, err)
+		}
+	}
+}
+
+func (txn *txn) commit() (*TxnResponse, error) {
+	r := &pb.TxnRequest{Compare: txn.cmps, Success: txn.sus, Failure: txn.fas}
+
+	var opts []grpc.CallOption
+	if !txn.isWrite {
+		opts = []grpc.CallOption{grpc.FailFast(false)}
+	}
+	resp, err := txn.kv.remote.Txn(txn.ctx, r, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return (*TxnResponse)(resp), nil
+}

vendor/github.com/coreos/etcd/clientv3/watch.go

@@ -0,0 +1,797 @@
+// Copyright 2016 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 clientv3
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	v3rpc "github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	mvccpb "github.com/coreos/etcd/mvcc/mvccpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+const (
+	EventTypeDelete = mvccpb.DELETE
+	EventTypePut    = mvccpb.PUT
+
+	closeSendErrTimeout = 250 * time.Millisecond
+)
+
+type Event mvccpb.Event
+
+type WatchChan <-chan WatchResponse
+
+type Watcher interface {
+	// Watch watches on a key or prefix. The watched events will be returned
+	// through the returned channel.
+	// If the watch is slow or the required rev is compacted, the watch request
+	// might be canceled from the server-side and the chan will be closed.
+	// 'opts' can be: 'WithRev' and/or 'WithPrefix'.
+	Watch(ctx context.Context, key string, opts ...OpOption) WatchChan
+
+	// Close closes the watcher and cancels all watch requests.
+	Close() error
+}
+
+type WatchResponse struct {
+	Header pb.ResponseHeader
+	Events []*Event
+
+	// CompactRevision is the minimum revision the watcher may receive.
+	CompactRevision int64
+
+	// Canceled is used to indicate watch failure.
+	// If the watch failed and the stream was about to close, before the channel is closed,
+	// the channel sends a final response that has Canceled set to true with a non-nil Err().
+	Canceled bool
+
+	// Created is used to indicate the creation of the watcher.
+	Created bool
+
+	closeErr error
+
+	// cancelReason is a reason of canceling watch
+	cancelReason string
+}
+
+// IsCreate returns true if the event tells that the key is newly created.
+func (e *Event) IsCreate() bool {
+	return e.Type == EventTypePut && e.Kv.CreateRevision == e.Kv.ModRevision
+}
+
+// IsModify returns true if the event tells that a new value is put on existing key.
+func (e *Event) IsModify() bool {
+	return e.Type == EventTypePut && e.Kv.CreateRevision != e.Kv.ModRevision
+}
+
+// Err is the error value if this WatchResponse holds an error.
+func (wr *WatchResponse) Err() error {
+	switch {
+	case wr.closeErr != nil:
+		return v3rpc.Error(wr.closeErr)
+	case wr.CompactRevision != 0:
+		return v3rpc.ErrCompacted
+	case wr.Canceled:
+		if len(wr.cancelReason) != 0 {
+			return v3rpc.Error(grpc.Errorf(codes.FailedPrecondition, "%s", wr.cancelReason))
+		}
+		return v3rpc.ErrFutureRev
+	}
+	return nil
+}
+
+// IsProgressNotify returns true if the WatchResponse is progress notification.
+func (wr *WatchResponse) IsProgressNotify() bool {
+	return len(wr.Events) == 0 && !wr.Canceled && !wr.Created && wr.CompactRevision == 0 && wr.Header.Revision != 0
+}
+
+// watcher implements the Watcher interface
+type watcher struct {
+	remote pb.WatchClient
+
+	// mu protects the grpc streams map
+	mu sync.RWMutex
+
+	// streams holds all the active grpc streams keyed by ctx value.
+	streams map[string]*watchGrpcStream
+}
+
+// watchGrpcStream tracks all watch resources attached to a single grpc stream.
+type watchGrpcStream struct {
+	owner  *watcher
+	remote pb.WatchClient
+
+	// ctx controls internal remote.Watch requests
+	ctx context.Context
+	// ctxKey is the key used when looking up this stream's context
+	ctxKey string
+	cancel context.CancelFunc
+
+	// substreams holds all active watchers on this grpc stream
+	substreams map[int64]*watcherStream
+	// resuming holds all resuming watchers on this grpc stream
+	resuming []*watcherStream
+
+	// reqc sends a watch request from Watch() to the main goroutine
+	reqc chan *watchRequest
+	// respc receives data from the watch client
+	respc chan *pb.WatchResponse
+	// donec closes to broadcast shutdown
+	donec chan struct{}
+	// errc transmits errors from grpc Recv to the watch stream reconn logic
+	errc chan error
+	// closingc gets the watcherStream of closing watchers
+	closingc chan *watcherStream
+	// wg is Done when all substream goroutines have exited
+	wg sync.WaitGroup
+
+	// resumec closes to signal that all substreams should begin resuming
+	resumec chan struct{}
+	// closeErr is the error that closed the watch stream
+	closeErr error
+}
+
+// watchRequest is issued by the subscriber to start a new watcher
+type watchRequest struct {
+	ctx context.Context
+	key string
+	end string
+	rev int64
+	// send created notification event if this field is true
+	createdNotify bool
+	// progressNotify is for progress updates
+	progressNotify bool
+	// filters is the list of events to filter out
+	filters []pb.WatchCreateRequest_FilterType
+	// get the previous key-value pair before the event happens
+	prevKV bool
+	// retc receives a chan WatchResponse once the watcher is established
+	retc chan chan WatchResponse
+}
+
+// watcherStream represents a registered watcher
+type watcherStream struct {
+	// initReq is the request that initiated this request
+	initReq watchRequest
+
+	// outc publishes watch responses to subscriber
+	outc chan WatchResponse
+	// recvc buffers watch responses before publishing
+	recvc chan *WatchResponse
+	// donec closes when the watcherStream goroutine stops.
+	donec chan struct{}
+	// closing is set to true when stream should be scheduled to shutdown.
+	closing bool
+	// id is the registered watch id on the grpc stream
+	id int64
+
+	// buf holds all events received from etcd but not yet consumed by the client
+	buf []*WatchResponse
+}
+
+func NewWatcher(c *Client) Watcher {
+	return NewWatchFromWatchClient(pb.NewWatchClient(c.conn))
+}
+
+func NewWatchFromWatchClient(wc pb.WatchClient) Watcher {
+	return &watcher{
+		remote:  wc,
+		streams: make(map[string]*watchGrpcStream),
+	}
+}
+
+// never closes
+var valCtxCh = make(chan struct{})
+var zeroTime = time.Unix(0, 0)
+
+// ctx with only the values; never Done
+type valCtx struct{ context.Context }
+
+func (vc *valCtx) Deadline() (time.Time, bool) { return zeroTime, false }
+func (vc *valCtx) Done() <-chan struct{}       { return valCtxCh }
+func (vc *valCtx) Err() error                  { return nil }
+
+func (w *watcher) newWatcherGrpcStream(inctx context.Context) *watchGrpcStream {
+	ctx, cancel := context.WithCancel(&valCtx{inctx})
+	wgs := &watchGrpcStream{
+		owner:      w,
+		remote:     w.remote,
+		ctx:        ctx,
+		ctxKey:     fmt.Sprintf("%v", inctx),
+		cancel:     cancel,
+		substreams: make(map[int64]*watcherStream),
+
+		respc:    make(chan *pb.WatchResponse),
+		reqc:     make(chan *watchRequest),
+		donec:    make(chan struct{}),
+		errc:     make(chan error, 1),
+		closingc: make(chan *watcherStream),
+		resumec:  make(chan struct{}),
+	}
+	go wgs.run()
+	return wgs
+}
+
+// Watch posts a watch request to run() and waits for a new watcher channel
+func (w *watcher) Watch(ctx context.Context, key string, opts ...OpOption) WatchChan {
+	ow := opWatch(key, opts...)
+
+	var filters []pb.WatchCreateRequest_FilterType
+	if ow.filterPut {
+		filters = append(filters, pb.WatchCreateRequest_NOPUT)
+	}
+	if ow.filterDelete {
+		filters = append(filters, pb.WatchCreateRequest_NODELETE)
+	}
+
+	wr := &watchRequest{
+		ctx:            ctx,
+		createdNotify:  ow.createdNotify,
+		key:            string(ow.key),
+		end:            string(ow.end),
+		rev:            ow.rev,
+		progressNotify: ow.progressNotify,
+		filters:        filters,
+		prevKV:         ow.prevKV,
+		retc:           make(chan chan WatchResponse, 1),
+	}
+
+	ok := false
+	ctxKey := fmt.Sprintf("%v", ctx)
+
+	// find or allocate appropriate grpc watch stream
+	w.mu.Lock()
+	if w.streams == nil {
+		// closed
+		w.mu.Unlock()
+		ch := make(chan WatchResponse)
+		close(ch)
+		return ch
+	}
+	wgs := w.streams[ctxKey]
+	if wgs == nil {
+		wgs = w.newWatcherGrpcStream(ctx)
+		w.streams[ctxKey] = wgs
+	}
+	donec := wgs.donec
+	reqc := wgs.reqc
+	w.mu.Unlock()
+
+	// couldn't create channel; return closed channel
+	closeCh := make(chan WatchResponse, 1)
+
+	// submit request
+	select {
+	case reqc <- wr:
+		ok = true
+	case <-wr.ctx.Done():
+	case <-donec:
+		if wgs.closeErr != nil {
+			closeCh <- WatchResponse{closeErr: wgs.closeErr}
+			break
+		}
+		// retry; may have dropped stream from no ctxs
+		return w.Watch(ctx, key, opts...)
+	}
+
+	// receive channel
+	if ok {
+		select {
+		case ret := <-wr.retc:
+			return ret
+		case <-ctx.Done():
+		case <-donec:
+			if wgs.closeErr != nil {
+				closeCh <- WatchResponse{closeErr: wgs.closeErr}
+				break
+			}
+			// retry; may have dropped stream from no ctxs
+			return w.Watch(ctx, key, opts...)
+		}
+	}
+
+	close(closeCh)
+	return closeCh
+}
+
+func (w *watcher) Close() (err error) {
+	w.mu.Lock()
+	streams := w.streams
+	w.streams = nil
+	w.mu.Unlock()
+	for _, wgs := range streams {
+		if werr := wgs.Close(); werr != nil {
+			err = werr
+		}
+	}
+	return err
+}
+
+func (w *watchGrpcStream) Close() (err error) {
+	w.cancel()
+	<-w.donec
+	select {
+	case err = <-w.errc:
+	default:
+	}
+	return toErr(w.ctx, err)
+}
+
+func (w *watcher) closeStream(wgs *watchGrpcStream) {
+	w.mu.Lock()
+	close(wgs.donec)
+	wgs.cancel()
+	if w.streams != nil {
+		delete(w.streams, wgs.ctxKey)
+	}
+	w.mu.Unlock()
+}
+
+func (w *watchGrpcStream) addSubstream(resp *pb.WatchResponse, ws *watcherStream) {
+	if resp.WatchId == -1 {
+		// failed; no channel
+		close(ws.recvc)
+		return
+	}
+	ws.id = resp.WatchId
+	w.substreams[ws.id] = ws
+}
+
+func (w *watchGrpcStream) sendCloseSubstream(ws *watcherStream, resp *WatchResponse) {
+	select {
+	case ws.outc <- *resp:
+	case <-ws.initReq.ctx.Done():
+	case <-time.After(closeSendErrTimeout):
+	}
+	close(ws.outc)
+}
+
+func (w *watchGrpcStream) closeSubstream(ws *watcherStream) {
+	// send channel response in case stream was never established
+	select {
+	case ws.initReq.retc <- ws.outc:
+	default:
+	}
+	// close subscriber's channel
+	if closeErr := w.closeErr; closeErr != nil && ws.initReq.ctx.Err() == nil {
+		go w.sendCloseSubstream(ws, &WatchResponse{closeErr: w.closeErr})
+	} else if ws.outc != nil {
+		close(ws.outc)
+	}
+	if ws.id != -1 {
+		delete(w.substreams, ws.id)
+		return
+	}
+	for i := range w.resuming {
+		if w.resuming[i] == ws {
+			w.resuming[i] = nil
+			return
+		}
+	}
+}
+
+// run is the root of the goroutines for managing a watcher client
+func (w *watchGrpcStream) run() {
+	var wc pb.Watch_WatchClient
+	var closeErr error
+
+	// substreams marked to close but goroutine still running; needed for
+	// avoiding double-closing recvc on grpc stream teardown
+	closing := make(map[*watcherStream]struct{})
+
+	defer func() {
+		w.closeErr = closeErr
+		// shutdown substreams and resuming substreams
+		for _, ws := range w.substreams {
+			if _, ok := closing[ws]; !ok {
+				close(ws.recvc)
+				closing[ws] = struct{}{}
+			}
+		}
+		for _, ws := range w.resuming {
+			if _, ok := closing[ws]; ws != nil && !ok {
+				close(ws.recvc)
+				closing[ws] = struct{}{}
+			}
+		}
+		w.joinSubstreams()
+		for range closing {
+			w.closeSubstream(<-w.closingc)
+		}
+		w.wg.Wait()
+		w.owner.closeStream(w)
+	}()
+
+	// start a stream with the etcd grpc server
+	if wc, closeErr = w.newWatchClient(); closeErr != nil {
+		return
+	}
+
+	cancelSet := make(map[int64]struct{})
+
+	for {
+		select {
+		// Watch() requested
+		case wreq := <-w.reqc:
+			outc := make(chan WatchResponse, 1)
+			ws := &watcherStream{
+				initReq: *wreq,
+				id:      -1,
+				outc:    outc,
+				// unbufffered so resumes won't cause repeat events
+				recvc: make(chan *WatchResponse),
+			}
+
+			ws.donec = make(chan struct{})
+			w.wg.Add(1)
+			go w.serveSubstream(ws, w.resumec)
+
+			// queue up for watcher creation/resume
+			w.resuming = append(w.resuming, ws)
+			if len(w.resuming) == 1 {
+				// head of resume queue, can register a new watcher
+				wc.Send(ws.initReq.toPB())
+			}
+		// New events from the watch client
+		case pbresp := <-w.respc:
+			switch {
+			case pbresp.Created:
+				// response to head of queue creation
+				if ws := w.resuming[0]; ws != nil {
+					w.addSubstream(pbresp, ws)
+					w.dispatchEvent(pbresp)
+					w.resuming[0] = nil
+				}
+				if ws := w.nextResume(); ws != nil {
+					wc.Send(ws.initReq.toPB())
+				}
+			case pbresp.Canceled:
+				delete(cancelSet, pbresp.WatchId)
+				if ws, ok := w.substreams[pbresp.WatchId]; ok {
+					// signal to stream goroutine to update closingc
+					close(ws.recvc)
+					closing[ws] = struct{}{}
+				}
+			default:
+				// dispatch to appropriate watch stream
+				if ok := w.dispatchEvent(pbresp); ok {
+					break
+				}
+				// watch response on unexpected watch id; cancel id
+				if _, ok := cancelSet[pbresp.WatchId]; ok {
+					break
+				}
+				cancelSet[pbresp.WatchId] = struct{}{}
+				cr := &pb.WatchRequest_CancelRequest{
+					CancelRequest: &pb.WatchCancelRequest{
+						WatchId: pbresp.WatchId,
+					},
+				}
+				req := &pb.WatchRequest{RequestUnion: cr}
+				wc.Send(req)
+			}
+		// watch client failed to recv; spawn another if possible
+		case err := <-w.errc:
+			if isHaltErr(w.ctx, err) || toErr(w.ctx, err) == v3rpc.ErrNoLeader {
+				closeErr = err
+				return
+			}
+			if wc, closeErr = w.newWatchClient(); closeErr != nil {
+				return
+			}
+			if ws := w.nextResume(); ws != nil {
+				wc.Send(ws.initReq.toPB())
+			}
+			cancelSet = make(map[int64]struct{})
+		case <-w.ctx.Done():
+			return
+		case ws := <-w.closingc:
+			w.closeSubstream(ws)
+			delete(closing, ws)
+			if len(w.substreams)+len(w.resuming) == 0 {
+				// no more watchers on this stream, shutdown
+				return
+			}
+		}
+	}
+}
+
+// nextResume chooses the next resuming to register with the grpc stream. Abandoned
+// streams are marked as nil in the queue since the head must wait for its inflight registration.
+func (w *watchGrpcStream) nextResume() *watcherStream {
+	for len(w.resuming) != 0 {
+		if w.resuming[0] != nil {
+			return w.resuming[0]
+		}
+		w.resuming = w.resuming[1:len(w.resuming)]
+	}
+	return nil
+}
+
+// dispatchEvent sends a WatchResponse to the appropriate watcher stream
+func (w *watchGrpcStream) dispatchEvent(pbresp *pb.WatchResponse) bool {
+	events := make([]*Event, len(pbresp.Events))
+	for i, ev := range pbresp.Events {
+		events[i] = (*Event)(ev)
+	}
+	wr := &WatchResponse{
+		Header:          *pbresp.Header,
+		Events:          events,
+		CompactRevision: pbresp.CompactRevision,
+		Created:         pbresp.Created,
+		Canceled:        pbresp.Canceled,
+		cancelReason:    pbresp.CancelReason,
+	}
+	ws, ok := w.substreams[pbresp.WatchId]
+	if !ok {
+		return false
+	}
+	select {
+	case ws.recvc <- wr:
+	case <-ws.donec:
+		return false
+	}
+	return true
+}
+
+// serveWatchClient forwards messages from the grpc stream to run()
+func (w *watchGrpcStream) serveWatchClient(wc pb.Watch_WatchClient) {
+	for {
+		resp, err := wc.Recv()
+		if err != nil {
+			select {
+			case w.errc <- err:
+			case <-w.donec:
+			}
+			return
+		}
+		select {
+		case w.respc <- resp:
+		case <-w.donec:
+			return
+		}
+	}
+}
+
+// serveSubstream forwards watch responses from run() to the subscriber
+func (w *watchGrpcStream) serveSubstream(ws *watcherStream, resumec chan struct{}) {
+	if ws.closing {
+		panic("created substream goroutine but substream is closing")
+	}
+
+	// nextRev is the minimum expected next revision
+	nextRev := ws.initReq.rev
+	resuming := false
+	defer func() {
+		if !resuming {
+			ws.closing = true
+		}
+		close(ws.donec)
+		if !resuming {
+			w.closingc <- ws
+		}
+		w.wg.Done()
+	}()
+
+	emptyWr := &WatchResponse{}
+	for {
+		curWr := emptyWr
+		outc := ws.outc
+
+		if len(ws.buf) > 0 {
+			curWr = ws.buf[0]
+		} else {
+			outc = nil
+		}
+		select {
+		case outc <- *curWr:
+			if ws.buf[0].Err() != nil {
+				return
+			}
+			ws.buf[0] = nil
+			ws.buf = ws.buf[1:]
+		case wr, ok := <-ws.recvc:
+			if !ok {
+				// shutdown from closeSubstream
+				return
+			}
+
+			if wr.Created {
+				if ws.initReq.retc != nil {
+					ws.initReq.retc <- ws.outc
+					// to prevent next write from taking the slot in buffered channel
+					// and posting duplicate create events
+					ws.initReq.retc = nil
+
+					// send first creation event only if requested
+					if ws.initReq.createdNotify {
+						ws.outc <- *wr
+					}
+					// once the watch channel is returned, a current revision
+					// watch must resume at the store revision. This is necessary
+					// for the following case to work as expected:
+					//	wch := m1.Watch("a")
+					//	m2.Put("a", "b")
+					//	<-wch
+					// If the revision is only bound on the first observed event,
+					// if wch is disconnected before the Put is issued, then reconnects
+					// after it is committed, it'll miss the Put.
+					if ws.initReq.rev == 0 {
+						nextRev = wr.Header.Revision
+					}
+				}
+			} else {
+				// current progress of watch; <= store revision
+				nextRev = wr.Header.Revision
+			}
+
+			if len(wr.Events) > 0 {
+				nextRev = wr.Events[len(wr.Events)-1].Kv.ModRevision + 1
+			}
+			ws.initReq.rev = nextRev
+
+			// created event is already sent above,
+			// watcher should not post duplicate events
+			if wr.Created {
+				continue
+			}
+
+			// TODO pause channel if buffer gets too large
+			ws.buf = append(ws.buf, wr)
+		case <-w.ctx.Done():
+			return
+		case <-ws.initReq.ctx.Done():
+			return
+		case <-resumec:
+			resuming = true
+			return
+		}
+	}
+	// lazily send cancel message if events on missing id
+}
+
+func (w *watchGrpcStream) newWatchClient() (pb.Watch_WatchClient, error) {
+	// mark all substreams as resuming
+	close(w.resumec)
+	w.resumec = make(chan struct{})
+	w.joinSubstreams()
+	for _, ws := range w.substreams {
+		ws.id = -1
+		w.resuming = append(w.resuming, ws)
+	}
+	// strip out nils, if any
+	var resuming []*watcherStream
+	for _, ws := range w.resuming {
+		if ws != nil {
+			resuming = append(resuming, ws)
+		}
+	}
+	w.resuming = resuming
+	w.substreams = make(map[int64]*watcherStream)
+
+	// connect to grpc stream while accepting watcher cancelation
+	stopc := make(chan struct{})
+	donec := w.waitCancelSubstreams(stopc)
+	wc, err := w.openWatchClient()
+	close(stopc)
+	<-donec
+
+	// serve all non-closing streams, even if there's a client error
+	// so that the teardown path can shutdown the streams as expected.
+	for _, ws := range w.resuming {
+		if ws.closing {
+			continue
+		}
+		ws.donec = make(chan struct{})
+		w.wg.Add(1)
+		go w.serveSubstream(ws, w.resumec)
+	}
+
+	if err != nil {
+		return nil, v3rpc.Error(err)
+	}
+
+	// receive data from new grpc stream
+	go w.serveWatchClient(wc)
+	return wc, nil
+}
+
+func (w *watchGrpcStream) waitCancelSubstreams(stopc <-chan struct{}) <-chan struct{} {
+	var wg sync.WaitGroup
+	wg.Add(len(w.resuming))
+	donec := make(chan struct{})
+	for i := range w.resuming {
+		go func(ws *watcherStream) {
+			defer wg.Done()
+			if ws.closing {
+				if ws.initReq.ctx.Err() != nil && ws.outc != nil {
+					close(ws.outc)
+					ws.outc = nil
+				}
+				return
+			}
+			select {
+			case <-ws.initReq.ctx.Done():
+				// closed ws will be removed from resuming
+				ws.closing = true
+				close(ws.outc)
+				ws.outc = nil
+				w.wg.Add(1)
+				go func() {
+					defer w.wg.Done()
+					w.closingc <- ws
+				}()
+			case <-stopc:
+			}
+		}(w.resuming[i])
+	}
+	go func() {
+		defer close(donec)
+		wg.Wait()
+	}()
+	return donec
+}
+
+// joinSubstream waits for all substream goroutines to complete
+func (w *watchGrpcStream) joinSubstreams() {
+	for _, ws := range w.substreams {
+		<-ws.donec
+	}
+	for _, ws := range w.resuming {
+		if ws != nil {
+			<-ws.donec
+		}
+	}
+}
+
+// openWatchClient retries opening a watchclient until retryConnection fails
+func (w *watchGrpcStream) openWatchClient() (ws pb.Watch_WatchClient, err error) {
+	for {
+		select {
+		case <-w.ctx.Done():
+			if err == nil {
+				return nil, w.ctx.Err()
+			}
+			return nil, err
+		default:
+		}
+		if ws, err = w.remote.Watch(w.ctx, grpc.FailFast(false)); ws != nil && err == nil {
+			break
+		}
+		if isHaltErr(w.ctx, err) {
+			return nil, v3rpc.Error(err)
+		}
+	}
+	return ws, nil
+}
+
+// toPB converts an internal watch request structure to its protobuf messagefunc (wr *watchRequest)
+func (wr *watchRequest) toPB() *pb.WatchRequest {
+	req := &pb.WatchCreateRequest{
+		StartRevision:  wr.rev,
+		Key:            []byte(wr.key),
+		RangeEnd:       []byte(wr.end),
+		ProgressNotify: wr.progressNotify,
+		Filters:        wr.filters,
+		PrevKv:         wr.prevKV,
+	}
+	cr := &pb.WatchRequest_CreateRequest{CreateRequest: req}
+	return &pb.WatchRequest{RequestUnion: cr}
+}