Update dependencies

2 files changed, 991 insertions, 0 deletions

diff --git a/vendor/google.golang.org/grpc/internal/channelz/funcs.go b/vendor/google.golang.org/grpc/internal/channelz/funcs.go
new file mode 100644
index 0000000..586a033
--- /dev/null
+++ b/vendor/google.golang.org/grpc/internal/channelz/funcs.go
@@ -0,0 +1,573 @@
+/*
+ *
+ * Copyright 2018 gRPC 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 channelz defines APIs for enabling channelz service, entry
+// registration/deletion, and accessing channelz data. It also defines channelz
+// metric struct formats.
+//
+// All APIs in this package are experimental.
+package channelz
+
+import (
+	"sort"
+	"sync"
+	"sync/atomic"
+
+	"google.golang.org/grpc/grpclog"
+)
+
+var (
+	db    dbWrapper
+	idGen idGenerator
+	// EntryPerPage defines the number of channelz entries to be shown on a web page.
+	EntryPerPage = 50
+	curState     int32
+)
+
+// TurnOn turns on channelz data collection.
+func TurnOn() {
+	if !IsOn() {
+		NewChannelzStorage()
+		atomic.StoreInt32(&curState, 1)
+	}
+}
+
+// IsOn returns whether channelz data collection is on.
+func IsOn() bool {
+	return atomic.CompareAndSwapInt32(&curState, 1, 1)
+}
+
+// dbWarpper wraps around a reference to internal channelz data storage, and
+// provide synchronized functionality to set and get the reference.
+type dbWrapper struct {
+	mu sync.RWMutex
+	DB *channelMap
+}
+
+func (d *dbWrapper) set(db *channelMap) {
+	d.mu.Lock()
+	d.DB = db
+	d.mu.Unlock()
+}
+
+func (d *dbWrapper) get() *channelMap {
+	d.mu.RLock()
+	defer d.mu.RUnlock()
+	return d.DB
+}
+
+// NewChannelzStorage initializes channelz data storage and id generator.
+//
+// Note: This function is exported for testing purpose only. User should not call
+// it in most cases.
+func NewChannelzStorage() {
+	db.set(&channelMap{
+		topLevelChannels: make(map[int64]struct{}),
+		channels:         make(map[int64]*channel),
+		listenSockets:    make(map[int64]*listenSocket),
+		normalSockets:    make(map[int64]*normalSocket),
+		servers:          make(map[int64]*server),
+		subChannels:      make(map[int64]*subChannel),
+	})
+	idGen.reset()
+}
+
+// GetTopChannels returns a slice of top channel's ChannelMetric, along with a
+// boolean indicating whether there's more top channels to be queried for.
+//
+// The arg id specifies that only top channel with id at or above it will be included
+// in the result. The returned slice is up to a length of EntryPerPage, and is
+// sorted in ascending id order.
+func GetTopChannels(id int64) ([]*ChannelMetric, bool) {
+	return db.get().GetTopChannels(id)
+}
+
+// GetServers returns a slice of server's ServerMetric, along with a
+// boolean indicating whether there's more servers to be queried for.
+//
+// The arg id specifies that only server with id at or above it will be included
+// in the result. The returned slice is up to a length of EntryPerPage, and is
+// sorted in ascending id order.
+func GetServers(id int64) ([]*ServerMetric, bool) {
+	return db.get().GetServers(id)
+}
+
+// GetServerSockets returns a slice of server's (identified by id) normal socket's
+// SocketMetric, along with a boolean indicating whether there's more sockets to
+// be queried for.
+//
+// The arg startID specifies that only sockets with id at or above it will be
+// included in the result. The returned slice is up to a length of EntryPerPage,
+// and is sorted in ascending id order.
+func GetServerSockets(id int64, startID int64) ([]*SocketMetric, bool) {
+	return db.get().GetServerSockets(id, startID)
+}
+
+// GetChannel returns the ChannelMetric for the channel (identified by id).
+func GetChannel(id int64) *ChannelMetric {
+	return db.get().GetChannel(id)
+}
+
+// GetSubChannel returns the SubChannelMetric for the subchannel (identified by id).
+func GetSubChannel(id int64) *SubChannelMetric {
+	return db.get().GetSubChannel(id)
+}
+
+// GetSocket returns the SocketInternalMetric for the socket (identified by id).
+func GetSocket(id int64) *SocketMetric {
+	return db.get().GetSocket(id)
+}
+
+// RegisterChannel registers the given channel c in channelz database with ref
+// as its reference name, and add it to the child list of its parent (identified
+// by pid). pid = 0 means no parent. It returns the unique channelz tracking id
+// assigned to this channel.
+func RegisterChannel(c Channel, pid int64, ref string) int64 {
+	id := idGen.genID()
+	cn := &channel{
+		refName:     ref,
+		c:           c,
+		subChans:    make(map[int64]string),
+		nestedChans: make(map[int64]string),
+		id:          id,
+		pid:         pid,
+	}
+	if pid == 0 {
+		db.get().addChannel(id, cn, true, pid, ref)
+	} else {
+		db.get().addChannel(id, cn, false, pid, ref)
+	}
+	return id
+}
+
+// RegisterSubChannel registers the given channel c in channelz database with ref
+// as its reference name, and add it to the child list of its parent (identified
+// by pid). It returns the unique channelz tracking id assigned to this subchannel.
+func RegisterSubChannel(c Channel, pid int64, ref string) int64 {
+	if pid == 0 {
+		grpclog.Error("a SubChannel's parent id cannot be 0")
+		return 0
+	}
+	id := idGen.genID()
+	sc := &subChannel{
+		refName: ref,
+		c:       c,
+		sockets: make(map[int64]string),
+		id:      id,
+		pid:     pid,
+	}
+	db.get().addSubChannel(id, sc, pid, ref)
+	return id
+}
+
+// RegisterServer registers the given server s in channelz database. It returns
+// the unique channelz tracking id assigned to this server.
+func RegisterServer(s Server, ref string) int64 {
+	id := idGen.genID()
+	svr := &server{
+		refName:       ref,
+		s:             s,
+		sockets:       make(map[int64]string),
+		listenSockets: make(map[int64]string),
+		id:            id,
+	}
+	db.get().addServer(id, svr)
+	return id
+}
+
+// RegisterListenSocket registers the given listen socket s in channelz database
+// with ref as its reference name, and add it to the child list of its parent
+// (identified by pid). It returns the unique channelz tracking id assigned to
+// this listen socket.
+func RegisterListenSocket(s Socket, pid int64, ref string) int64 {
+	if pid == 0 {
+		grpclog.Error("a ListenSocket's parent id cannot be 0")
+		return 0
+	}
+	id := idGen.genID()
+	ls := &listenSocket{refName: ref, s: s, id: id, pid: pid}
+	db.get().addListenSocket(id, ls, pid, ref)
+	return id
+}
+
+// RegisterNormalSocket registers the given normal socket s in channelz database
+// with ref as its reference name, and add it to the child list of its parent
+// (identified by pid). It returns the unique channelz tracking id assigned to
+// this normal socket.
+func RegisterNormalSocket(s Socket, pid int64, ref string) int64 {
+	if pid == 0 {
+		grpclog.Error("a NormalSocket's parent id cannot be 0")
+		return 0
+	}
+	id := idGen.genID()
+	ns := &normalSocket{refName: ref, s: s, id: id, pid: pid}
+	db.get().addNormalSocket(id, ns, pid, ref)
+	return id
+}
+
+// RemoveEntry removes an entry with unique channelz trakcing id to be id from
+// channelz database.
+func RemoveEntry(id int64) {
+	db.get().removeEntry(id)
+}
+
+// channelMap is the storage data structure for channelz.
+// Methods of channelMap can be divided in two two categories with respect to locking.
+// 1. Methods acquire the global lock.
+// 2. Methods that can only be called when global lock is held.
+// A second type of method need always to be called inside a first type of method.
+type channelMap struct {
+	mu               sync.RWMutex
+	topLevelChannels map[int64]struct{}
+	servers          map[int64]*server
+	channels         map[int64]*channel
+	subChannels      map[int64]*subChannel
+	listenSockets    map[int64]*listenSocket
+	normalSockets    map[int64]*normalSocket
+}
+
+func (c *channelMap) addServer(id int64, s *server) {
+	c.mu.Lock()
+	s.cm = c
+	c.servers[id] = s
+	c.mu.Unlock()
+}
+
+func (c *channelMap) addChannel(id int64, cn *channel, isTopChannel bool, pid int64, ref string) {
+	c.mu.Lock()
+	cn.cm = c
+	c.channels[id] = cn
+	if isTopChannel {
+		c.topLevelChannels[id] = struct{}{}
+	} else {
+		c.findEntry(pid).addChild(id, cn)
+	}
+	c.mu.Unlock()
+}
+
+func (c *channelMap) addSubChannel(id int64, sc *subChannel, pid int64, ref string) {
+	c.mu.Lock()
+	sc.cm = c
+	c.subChannels[id] = sc
+	c.findEntry(pid).addChild(id, sc)
+	c.mu.Unlock()
+}
+
+func (c *channelMap) addListenSocket(id int64, ls *listenSocket, pid int64, ref string) {
+	c.mu.Lock()
+	ls.cm = c
+	c.listenSockets[id] = ls
+	c.findEntry(pid).addChild(id, ls)
+	c.mu.Unlock()
+}
+
+func (c *channelMap) addNormalSocket(id int64, ns *normalSocket, pid int64, ref string) {
+	c.mu.Lock()
+	ns.cm = c
+	c.normalSockets[id] = ns
+	c.findEntry(pid).addChild(id, ns)
+	c.mu.Unlock()
+}
+
+// removeEntry triggers the removal of an entry, which may not indeed delete the
+// entry, if it has to wait on the deletion of its children, or may lead to a chain
+// of entry deletion. For example, deleting the last socket of a gracefully shutting
+// down server will lead to the server being also deleted.
+func (c *channelMap) removeEntry(id int64) {
+	c.mu.Lock()
+	c.findEntry(id).triggerDelete()
+	c.mu.Unlock()
+}
+
+// c.mu must be held by the caller.
+func (c *channelMap) findEntry(id int64) entry {
+	var v entry
+	var ok bool
+	if v, ok = c.channels[id]; ok {
+		return v
+	}
+	if v, ok = c.subChannels[id]; ok {
+		return v
+	}
+	if v, ok = c.servers[id]; ok {
+		return v
+	}
+	if v, ok = c.listenSockets[id]; ok {
+		return v
+	}
+	if v, ok = c.normalSockets[id]; ok {
+		return v
+	}
+	return &dummyEntry{idNotFound: id}
+}
+
+// c.mu must be held by the caller
+// deleteEntry simply deletes an entry from the channelMap. Before calling this
+// method, caller must check this entry is ready to be deleted, i.e removeEntry()
+// has been called on it, and no children still exist.
+// Conditionals are ordered by the expected frequency of deletion of each entity
+// type, in order to optimize performance.
+func (c *channelMap) deleteEntry(id int64) {
+	var ok bool
+	if _, ok = c.normalSockets[id]; ok {
+		delete(c.normalSockets, id)
+		return
+	}
+	if _, ok = c.subChannels[id]; ok {
+		delete(c.subChannels, id)
+		return
+	}
+	if _, ok = c.channels[id]; ok {
+		delete(c.channels, id)
+		delete(c.topLevelChannels, id)
+		return
+	}
+	if _, ok = c.listenSockets[id]; ok {
+		delete(c.listenSockets, id)
+		return
+	}
+	if _, ok = c.servers[id]; ok {
+		delete(c.servers, id)
+		return
+	}
+}
+
+type int64Slice []int64
+
+func (s int64Slice) Len() int           { return len(s) }
+func (s int64Slice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s int64Slice) Less(i, j int) bool { return s[i] < s[j] }
+
+func copyMap(m map[int64]string) map[int64]string {
+	n := make(map[int64]string)
+	for k, v := range m {
+		n[k] = v
+	}
+	return n
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func (c *channelMap) GetTopChannels(id int64) ([]*ChannelMetric, bool) {
+	c.mu.RLock()
+	l := len(c.topLevelChannels)
+	ids := make([]int64, 0, l)
+	cns := make([]*channel, 0, min(l, EntryPerPage))
+
+	for k := range c.topLevelChannels {
+		ids = append(ids, k)
+	}
+	sort.Sort(int64Slice(ids))
+	idx := sort.Search(len(ids), func(i int) bool { return ids[i] >= id })
+	count := 0
+	var end bool
+	var t []*ChannelMetric
+	for i, v := range ids[idx:] {
+		if count == EntryPerPage {
+			break
+		}
+		if cn, ok := c.channels[v]; ok {
+			cns = append(cns, cn)
+			t = append(t, &ChannelMetric{
+				NestedChans: copyMap(cn.nestedChans),
+				SubChans:    copyMap(cn.subChans),
+			})
+			count++
+		}
+		if i == len(ids[idx:])-1 {
+			end = true
+			break
+		}
+	}
+	c.mu.RUnlock()
+	if count == 0 {
+		end = true
+	}
+
+	for i, cn := range cns {
+		t[i].ChannelData = cn.c.ChannelzMetric()
+		t[i].ID = cn.id
+		t[i].RefName = cn.refName
+	}
+	return t, end
+}
+
+func (c *channelMap) GetServers(id int64) ([]*ServerMetric, bool) {
+	c.mu.RLock()
+	l := len(c.servers)
+	ids := make([]int64, 0, l)
+	ss := make([]*server, 0, min(l, EntryPerPage))
+	for k := range c.servers {
+		ids = append(ids, k)
+	}
+	sort.Sort(int64Slice(ids))
+	idx := sort.Search(len(ids), func(i int) bool { return ids[i] >= id })
+	count := 0
+	var end bool
+	var s []*ServerMetric
+	for i, v := range ids[idx:] {
+		if count == EntryPerPage {
+			break
+		}
+		if svr, ok := c.servers[v]; ok {
+			ss = append(ss, svr)
+			s = append(s, &ServerMetric{
+				ListenSockets: copyMap(svr.listenSockets),
+			})
+			count++
+		}
+		if i == len(ids[idx:])-1 {
+			end = true
+			break
+		}
+	}
+	c.mu.RUnlock()
+	if count == 0 {
+		end = true
+	}
+
+	for i, svr := range ss {
+		s[i].ServerData = svr.s.ChannelzMetric()
+		s[i].ID = svr.id
+		s[i].RefName = svr.refName
+	}
+	return s, end
+}
+
+func (c *channelMap) GetServerSockets(id int64, startID int64) ([]*SocketMetric, bool) {
+	var svr *server
+	var ok bool
+	c.mu.RLock()
+	if svr, ok = c.servers[id]; !ok {
+		// server with id doesn't exist.
+		c.mu.RUnlock()
+		return nil, true
+	}
+	svrskts := svr.sockets
+	l := len(svrskts)
+	ids := make([]int64, 0, l)
+	sks := make([]*normalSocket, 0, min(l, EntryPerPage))
+	for k := range svrskts {
+		ids = append(ids, k)
+	}
+	sort.Sort((int64Slice(ids)))
+	idx := sort.Search(len(ids), func(i int) bool { return ids[i] >= id })
+	count := 0
+	var end bool
+	for i, v := range ids[idx:] {
+		if count == EntryPerPage {
+			break
+		}
+		if ns, ok := c.normalSockets[v]; ok {
+			sks = append(sks, ns)
+			count++
+		}
+		if i == len(ids[idx:])-1 {
+			end = true
+			break
+		}
+	}
+	c.mu.RUnlock()
+	if count == 0 {
+		end = true
+	}
+	var s []*SocketMetric
+	for _, ns := range sks {
+		sm := &SocketMetric{}
+		sm.SocketData = ns.s.ChannelzMetric()
+		sm.ID = ns.id
+		sm.RefName = ns.refName
+		s = append(s, sm)
+	}
+	return s, end
+}
+
+func (c *channelMap) GetChannel(id int64) *ChannelMetric {
+	cm := &ChannelMetric{}
+	var cn *channel
+	var ok bool
+	c.mu.RLock()
+	if cn, ok = c.channels[id]; !ok {
+		// channel with id doesn't exist.
+		c.mu.RUnlock()
+		return nil
+	}
+	cm.NestedChans = copyMap(cn.nestedChans)
+	cm.SubChans = copyMap(cn.subChans)
+	c.mu.RUnlock()
+	cm.ChannelData = cn.c.ChannelzMetric()
+	cm.ID = cn.id
+	cm.RefName = cn.refName
+	return cm
+}
+
+func (c *channelMap) GetSubChannel(id int64) *SubChannelMetric {
+	cm := &SubChannelMetric{}
+	var sc *subChannel
+	var ok bool
+	c.mu.RLock()
+	if sc, ok = c.subChannels[id]; !ok {
+		// subchannel with id doesn't exist.
+		c.mu.RUnlock()
+		return nil
+	}
+	cm.Sockets = copyMap(sc.sockets)
+	c.mu.RUnlock()
+	cm.ChannelData = sc.c.ChannelzMetric()
+	cm.ID = sc.id
+	cm.RefName = sc.refName
+	return cm
+}
+
+func (c *channelMap) GetSocket(id int64) *SocketMetric {
+	sm := &SocketMetric{}
+	c.mu.RLock()
+	if ls, ok := c.listenSockets[id]; ok {
+		c.mu.RUnlock()
+		sm.SocketData = ls.s.ChannelzMetric()
+		sm.ID = ls.id
+		sm.RefName = ls.refName
+		return sm
+	}
+	if ns, ok := c.normalSockets[id]; ok {
+		c.mu.RUnlock()
+		sm.SocketData = ns.s.ChannelzMetric()
+		sm.ID = ns.id
+		sm.RefName = ns.refName
+		return sm
+	}
+	c.mu.RUnlock()
+	return nil
+}
+
+type idGenerator struct {
+	id int64
+}
+
+func (i *idGenerator) reset() {
+	atomic.StoreInt64(&i.id, 0)
+}
+
+func (i *idGenerator) genID() int64 {
+	return atomic.AddInt64(&i.id, 1)
+}
diff --git a/vendor/google.golang.org/grpc/internal/channelz/types.go b/vendor/google.golang.org/grpc/internal/channelz/types.go
new file mode 100644
index 0000000..153d753
--- /dev/null
+++ b/vendor/google.golang.org/grpc/internal/channelz/types.go
@@ -0,0 +1,418 @@
+/*
+ *
+ * Copyright 2018 gRPC 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 channelz
+
+import (
+	"net"
+	"time"
+
+	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/grpclog"
+)
+
+// entry represents a node in the channelz database.
+type entry interface {
+	// addChild adds a child e, whose channelz id is id to child list
+	addChild(id int64, e entry)
+	// deleteChild deletes a child with channelz id to be id from child list
+	deleteChild(id int64)
+	// triggerDelete tries to delete self from channelz database. However, if child
+	// list is not empty, then deletion from the database is on hold until the last
+	// child is deleted from database.
+	triggerDelete()
+	// deleteSelfIfReady check whether triggerDelete() has been called before, and whether child
+	// list is now empty. If both conditions are met, then delete self from database.
+	deleteSelfIfReady()
+}
+
+// dummyEntry is a fake entry to handle entry not found case.
+type dummyEntry struct {
+	idNotFound int64
+}
+
+func (d *dummyEntry) addChild(id int64, e entry) {
+	// Note: It is possible for a normal program to reach here under race condition.
+	// For example, there could be a race between ClientConn.Close() info being propagated
+	// to addrConn and http2Client. ClientConn.Close() cancel the context and result
+	// in http2Client to error. The error info is then caught by transport monitor
+	// and before addrConn.tearDown() is called in side ClientConn.Close(). Therefore,
+	// the addrConn will create a new transport. And when registering the new transport in
+	// channelz, its parent addrConn could have already been torn down and deleted
+	// from channelz tracking, and thus reach the code here.
+	grpclog.Infof("attempt to add child of type %T with id %d to a parent (id=%d) that doesn't currently exist", e, id, d.idNotFound)
+}
+
+func (d *dummyEntry) deleteChild(id int64) {
+	// It is possible for a normal program to reach here under race condition.
+	// Refer to the example described in addChild().
+	grpclog.Infof("attempt to delete child with id %d from a parent (id=%d) that doesn't currently exist", id, d.idNotFound)
+}
+
+func (d *dummyEntry) triggerDelete() {
+	grpclog.Warningf("attempt to delete an entry (id=%d) that doesn't currently exist", d.idNotFound)
+}
+
+func (*dummyEntry) deleteSelfIfReady() {
+	// code should not reach here. deleteSelfIfReady is always called on an existing entry.
+}
+
+// ChannelMetric defines the info channelz provides for a specific Channel, which
+// includes ChannelInternalMetric and channelz-specific data, such as channelz id,
+// child list, etc.
+type ChannelMetric struct {
+	// ID is the channelz id of this channel.
+	ID int64
+	// RefName is the human readable reference string of this channel.
+	RefName string
+	// ChannelData contains channel internal metric reported by the channel through
+	// ChannelzMetric().
+	ChannelData *ChannelInternalMetric
+	// NestedChans tracks the nested channel type children of this channel in the format of
+	// a map from nested channel channelz id to corresponding reference string.
+	NestedChans map[int64]string
+	// SubChans tracks the subchannel type children of this channel in the format of a
+	// map from subchannel channelz id to corresponding reference string.
+	SubChans map[int64]string
+	// Sockets tracks the socket type children of this channel in the format of a map
+	// from socket channelz id to corresponding reference string.
+	// Note current grpc implementation doesn't allow channel having sockets directly,
+	// therefore, this is field is unused.
+	Sockets map[int64]string
+}
+
+// SubChannelMetric defines the info channelz provides for a specific SubChannel,
+// which includes ChannelInternalMetric and channelz-specific data, such as
+// channelz id, child list, etc.
+type SubChannelMetric struct {
+	// ID is the channelz id of this subchannel.
+	ID int64
+	// RefName is the human readable reference string of this subchannel.
+	RefName string
+	// ChannelData contains subchannel internal metric reported by the subchannel
+	// through ChannelzMetric().
+	ChannelData *ChannelInternalMetric
+	// NestedChans tracks the nested channel type children of this subchannel in the format of
+	// a map from nested channel channelz id to corresponding reference string.
+	// Note current grpc implementation doesn't allow subchannel to have nested channels
+	// as children, therefore, this field is unused.
+	NestedChans map[int64]string
+	// SubChans tracks the subchannel type children of this subchannel in the format of a
+	// map from subchannel channelz id to corresponding reference string.
+	// Note current grpc implementation doesn't allow subchannel to have subchannels
+	// as children, therefore, this field is unused.
+	SubChans map[int64]string
+	// Sockets tracks the socket type children of this subchannel in the format of a map
+	// from socket channelz id to corresponding reference string.
+	Sockets map[int64]string
+}
+
+// ChannelInternalMetric defines the struct that the implementor of Channel interface
+// should return from ChannelzMetric().
+type ChannelInternalMetric struct {
+	// current connectivity state of the channel.
+	State connectivity.State
+	// The target this channel originally tried to connect to.  May be absent
+	Target string
+	// The number of calls started on the channel.
+	CallsStarted int64
+	// The number of calls that have completed with an OK status.
+	CallsSucceeded int64
+	// The number of calls that have a completed with a non-OK status.
+	CallsFailed int64
+	// The last time a call was started on the channel.
+	LastCallStartedTimestamp time.Time
+	//TODO: trace
+}
+
+// Channel is the interface that should be satisfied in order to be tracked by
+// channelz as Channel or SubChannel.
+type Channel interface {
+	ChannelzMetric() *ChannelInternalMetric
+}
+
+type channel struct {
+	refName     string
+	c           Channel
+	closeCalled bool
+	nestedChans map[int64]string
+	subChans    map[int64]string
+	id          int64
+	pid         int64
+	cm          *channelMap
+}
+
+func (c *channel) addChild(id int64, e entry) {
+	switch v := e.(type) {
+	case *subChannel:
+		c.subChans[id] = v.refName
+	case *channel:
+		c.nestedChans[id] = v.refName
+	default:
+		grpclog.Errorf("cannot add a child (id = %d) of type %T to a channel", id, e)
+	}
+}
+
+func (c *channel) deleteChild(id int64) {
+	delete(c.subChans, id)
+	delete(c.nestedChans, id)
+	c.deleteSelfIfReady()
+}
+
+func (c *channel) triggerDelete() {
+	c.closeCalled = true
+	c.deleteSelfIfReady()
+}
+
+func (c *channel) deleteSelfIfReady() {
+	if !c.closeCalled || len(c.subChans)+len(c.nestedChans) != 0 {
+		return
+	}
+	c.cm.deleteEntry(c.id)
+	// not top channel
+	if c.pid != 0 {
+		c.cm.findEntry(c.pid).deleteChild(c.id)
+	}
+}
+
+type subChannel struct {
+	refName     string
+	c           Channel
+	closeCalled bool
+	sockets     map[int64]string
+	id          int64
+	pid         int64
+	cm          *channelMap
+}
+
+func (sc *subChannel) addChild(id int64, e entry) {
+	if v, ok := e.(*normalSocket); ok {
+		sc.sockets[id] = v.refName
+	} else {
+		grpclog.Errorf("cannot add a child (id = %d) of type %T to a subChannel", id, e)
+	}
+}
+
+func (sc *subChannel) deleteChild(id int64) {
+	delete(sc.sockets, id)
+	sc.deleteSelfIfReady()
+}
+
+func (sc *subChannel) triggerDelete() {
+	sc.closeCalled = true
+	sc.deleteSelfIfReady()
+}
+
+func (sc *subChannel) deleteSelfIfReady() {
+	if !sc.closeCalled || len(sc.sockets) != 0 {
+		return
+	}
+	sc.cm.deleteEntry(sc.id)
+	sc.cm.findEntry(sc.pid).deleteChild(sc.id)
+}
+
+// SocketMetric defines the info channelz provides for a specific Socket, which
+// includes SocketInternalMetric and channelz-specific data, such as channelz id, etc.
+type SocketMetric struct {
+	// ID is the channelz id of this socket.
+	ID int64
+	// RefName is the human readable reference string of this socket.
+	RefName string
+	// SocketData contains socket internal metric reported by the socket through
+	// ChannelzMetric().
+	SocketData *SocketInternalMetric
+}
+
+// SocketInternalMetric defines the struct that the implementor of Socket interface
+// should return from ChannelzMetric().
+type SocketInternalMetric struct {
+	// The number of streams that have been started.
+	StreamsStarted int64
+	// The number of streams that have ended successfully:
+	// On client side, receiving frame with eos bit set.
+	// On server side, sending frame with eos bit set.
+	StreamsSucceeded int64
+	// The number of streams that have ended unsuccessfully:
+	// On client side, termination without receiving frame with eos bit set.
+	// On server side, termination without sending frame with eos bit set.
+	StreamsFailed int64
+	// The number of messages successfully sent on this socket.
+	MessagesSent     int64
+	MessagesReceived int64
+	// The number of keep alives sent.  This is typically implemented with HTTP/2
+	// ping messages.
+	KeepAlivesSent int64
+	// The last time a stream was created by this endpoint.  Usually unset for
+	// servers.
+	LastLocalStreamCreatedTimestamp time.Time
+	// The last time a stream was created by the remote endpoint.  Usually unset
+	// for clients.
+	LastRemoteStreamCreatedTimestamp time.Time
+	// The last time a message was sent by this endpoint.
+	LastMessageSentTimestamp time.Time
+	// The last time a message was received by this endpoint.
+	LastMessageReceivedTimestamp time.Time
+	// The amount of window, granted to the local endpoint by the remote endpoint.
+	// This may be slightly out of date due to network latency.  This does NOT
+	// include stream level or TCP level flow control info.
+	LocalFlowControlWindow int64
+	// The amount of window, granted to the remote endpoint by the local endpoint.
+	// This may be slightly out of date due to network latency.  This does NOT
+	// include stream level or TCP level flow control info.
+	RemoteFlowControlWindow int64
+	// The locally bound address.
+	LocalAddr net.Addr
+	// The remote bound address.  May be absent.
+	RemoteAddr net.Addr
+	// Optional, represents the name of the remote endpoint, if different than
+	// the original target name.
+	RemoteName string
+	//TODO: socket options
+	//TODO: Security
+}
+
+// Socket is the interface that should be satisfied in order to be tracked by
+// channelz as Socket.
+type Socket interface {
+	ChannelzMetric() *SocketInternalMetric
+}
+
+type listenSocket struct {
+	refName string
+	s       Socket
+	id      int64
+	pid     int64
+	cm      *channelMap
+}
+
+func (ls *listenSocket) addChild(id int64, e entry) {
+	grpclog.Errorf("cannot add a child (id = %d) of type %T to a listen socket", id, e)
+}
+
+func (ls *listenSocket) deleteChild(id int64) {
+	grpclog.Errorf("cannot delete a child (id = %d) from a listen socket", id)
+}
+
+func (ls *listenSocket) triggerDelete() {
+	ls.cm.deleteEntry(ls.id)
+	ls.cm.findEntry(ls.pid).deleteChild(ls.id)
+}
+
+func (ls *listenSocket) deleteSelfIfReady() {
+	grpclog.Errorf("cannot call deleteSelfIfReady on a listen socket")
+}
+
+type normalSocket struct {
+	refName string
+	s       Socket
+	id      int64
+	pid     int64
+	cm      *channelMap
+}
+
+func (ns *normalSocket) addChild(id int64, e entry) {
+	grpclog.Errorf("cannot add a child (id = %d) of type %T to a normal socket", id, e)
+}
+
+func (ns *normalSocket) deleteChild(id int64) {
+	grpclog.Errorf("cannot delete a child (id = %d) from a normal socket", id)
+}
+
+func (ns *normalSocket) triggerDelete() {
+	ns.cm.deleteEntry(ns.id)
+	ns.cm.findEntry(ns.pid).deleteChild(ns.id)
+}
+
+func (ns *normalSocket) deleteSelfIfReady() {
+	grpclog.Errorf("cannot call deleteSelfIfReady on a normal socket")
+}
+
+// ServerMetric defines the info channelz provides for a specific Server, which
+// includes ServerInternalMetric and channelz-specific data, such as channelz id,
+// child list, etc.
+type ServerMetric struct {
+	// ID is the channelz id of this server.
+	ID int64
+	// RefName is the human readable reference string of this server.
+	RefName string
+	// ServerData contains server internal metric reported by the server through
+	// ChannelzMetric().
+	ServerData *ServerInternalMetric
+	// ListenSockets tracks the listener socket type children of this server in the
+	// format of a map from socket channelz id to corresponding reference string.
+	ListenSockets map[int64]string
+}
+
+// ServerInternalMetric defines the struct that the implementor of Server interface
+// should return from ChannelzMetric().
+type ServerInternalMetric struct {
+	// The number of incoming calls started on the server.
+	CallsStarted int64
+	// The number of incoming calls that have completed with an OK status.
+	CallsSucceeded int64
+	// The number of incoming calls that have a completed with a non-OK status.
+	CallsFailed int64
+	// The last time a call was started on the server.
+	LastCallStartedTimestamp time.Time
+	//TODO: trace
+}
+
+// Server is the interface to be satisfied in order to be tracked by channelz as
+// Server.
+type Server interface {
+	ChannelzMetric() *ServerInternalMetric
+}
+
+type server struct {
+	refName       string
+	s             Server
+	closeCalled   bool
+	sockets       map[int64]string
+	listenSockets map[int64]string
+	id            int64
+	cm            *channelMap
+}
+
+func (s *server) addChild(id int64, e entry) {
+	switch v := e.(type) {
+	case *normalSocket:
+		s.sockets[id] = v.refName
+	case *listenSocket:
+		s.listenSockets[id] = v.refName
+	default:
+		grpclog.Errorf("cannot add a child (id = %d) of type %T to a server", id, e)
+	}
+}
+
+func (s *server) deleteChild(id int64) {
+	delete(s.sockets, id)
+	delete(s.listenSockets, id)
+	s.deleteSelfIfReady()
+}
+
+func (s *server) triggerDelete() {
+	s.closeCalled = true
+	s.deleteSelfIfReady()
+}
+
+func (s *server) deleteSelfIfReady() {
+	if !s.closeCalled || len(s.sockets)+len(s.listenSockets) != 0 {
+		return
+	}
+	s.cm.deleteEntry(s.id)
+}