TUN-1734: Pin packages at exact versions

vendor/google.golang.org/grpc/internal/channelz/funcs.go

@@ -27,16 +27,22 @@ import (
 	"sort"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"google.golang.org/grpc/grpclog"
 )
 
+const (
+	defaultMaxTraceEntry int32 = 30
+)
+
 var (
 	db    dbWrapper
 	idGen idGenerator
 	// EntryPerPage defines the number of channelz entries to be shown on a web page.
-	EntryPerPage = 50
-	curState     int32
+	EntryPerPage  = int64(50)
+	curState      int32
+	maxTraceEntry = defaultMaxTraceEntry
 )
 
 // TurnOn turns on channelz data collection.
@@ -52,6 +58,22 @@ func IsOn() bool {
 	return atomic.CompareAndSwapInt32(&curState, 1, 1)
 }
 
+// SetMaxTraceEntry sets maximum number of trace entry per entity (i.e. channel/subchannel).
+// Setting it to 0 will disable channel tracing.
+func SetMaxTraceEntry(i int32) {
+	atomic.StoreInt32(&maxTraceEntry, i)
+}
+
+// ResetMaxTraceEntryToDefault resets the maximum number of trace entry per entity to default.
+func ResetMaxTraceEntryToDefault() {
+	atomic.StoreInt32(&maxTraceEntry, defaultMaxTraceEntry)
+}
+
+func getMaxTraceEntry() int {
+	i := atomic.LoadInt32(&maxTraceEntry)
+	return int(i)
+}
+
 // dbWarpper wraps around a reference to internal channelz data storage, and
 // provide synchronized functionality to set and get the reference.
 type dbWrapper struct {
@@ -91,20 +113,20 @@ func NewChannelzStorage() {
 // 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)
+// in the result. The returned slice is up to a length of the arg maxResults or
+// EntryPerPage if maxResults is zero, and is sorted in ascending id order.
+func GetTopChannels(id int64, maxResults int64) ([]*ChannelMetric, bool) {
+	return db.get().GetTopChannels(id, maxResults)
 }
 
 // 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)
+// in the result. The returned slice is up to a length of the arg maxResults or
+// EntryPerPage if maxResults is zero, and is sorted in ascending id order.
+func GetServers(id int64, maxResults int64) ([]*ServerMetric, bool) {
+	return db.get().GetServers(id, maxResults)
 }
 
 // GetServerSockets returns a slice of server's (identified by id) normal socket's
@@ -112,10 +134,10 @@ func GetServers(id int64) ([]*ServerMetric, bool) {
 // 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)
+// included in the result. The returned slice is up to a length of the arg maxResults
+// or EntryPerPage if maxResults is zero, and is sorted in ascending id order.
+func GetServerSockets(id int64, startID int64, maxResults int64) ([]*SocketMetric, bool) {
+	return db.get().GetServerSockets(id, startID, maxResults)
 }
 
 // GetChannel returns the ChannelMetric for the channel (identified by id).
@@ -133,6 +155,11 @@ func GetSocket(id int64) *SocketMetric {
 	return db.get().GetSocket(id)
 }
 
+// GetServer returns the ServerMetric for the server (identified by id).
+func GetServer(id int64) *ServerMetric {
+	return db.get().GetServer(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
@@ -146,6 +173,7 @@ func RegisterChannel(c Channel, pid int64, ref string) int64 {
 		nestedChans: make(map[int64]string),
 		id:          id,
 		pid:         pid,
+		trace:       &channelTrace{createdTime: time.Now(), events: make([]*TraceEvent, 0, getMaxTraceEntry())},
 	}
 	if pid == 0 {
 		db.get().addChannel(id, cn, true, pid, ref)
@@ -170,6 +198,7 @@ func RegisterSubChannel(c Channel, pid int64, ref string) int64 {
 		sockets: make(map[int64]string),
 		id:      id,
 		pid:     pid,
+		trace:   &channelTrace{createdTime: time.Now(), events: make([]*TraceEvent, 0, getMaxTraceEntry())},
 	}
 	db.get().addSubChannel(id, sc, pid, ref)
 	return id
@@ -226,6 +255,24 @@ func RemoveEntry(id int64) {
 	db.get().removeEntry(id)
 }
 
+// TraceEventDesc is what the caller of AddTraceEvent should provide to describe the event to be added
+// to the channel trace.
+// The Parent field is optional. It is used for event that will be recorded in the entity's parent
+// trace also.
+type TraceEventDesc struct {
+	Desc     string
+	Severity Severity
+	Parent   *TraceEventDesc
+}
+
+// AddTraceEvent adds trace related to the entity with specified id, using the provided TraceEventDesc.
+func AddTraceEvent(id int64, desc *TraceEventDesc) {
+	if getMaxTraceEntry() == 0 {
+		return
+	}
+	db.get().traceEvent(id, desc)
+}
+
 // 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.
@@ -251,6 +298,7 @@ func (c *channelMap) addServer(id int64, s *server) {
 func (c *channelMap) addChannel(id int64, cn *channel, isTopChannel bool, pid int64, ref string) {
 	c.mu.Lock()
 	cn.cm = c
+	cn.trace.cm = c
 	c.channels[id] = cn
 	if isTopChannel {
 		c.topLevelChannels[id] = struct{}{}
@@ -263,6 +311,7 @@ func (c *channelMap) addChannel(id int64, cn *channel, isTopChannel bool, pid in
 func (c *channelMap) addSubChannel(id int64, sc *subChannel, pid int64, ref string) {
 	c.mu.Lock()
 	sc.cm = c
+	sc.trace.cm = c
 	c.subChannels[id] = sc
 	c.findEntry(pid).addChild(id, sc)
 	c.mu.Unlock()
@@ -284,16 +333,25 @@ func (c *channelMap) addNormalSocket(id int64, ns *normalSocket, pid int64, ref
 	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.
+// 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 and until no other entity's channel trace references it.
+// It 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) decrTraceRefCount(id int64) {
+	e := c.findEntry(id)
+	if v, ok := e.(tracedChannel); ok {
+		v.decrTraceRefCount()
+		e.deleteSelfIfReady()
+	}
+}
+
 // c.mu must be held by the caller.
 func (c *channelMap) findEntry(id int64) entry {
 	var v entry
@@ -347,6 +405,39 @@ func (c *channelMap) deleteEntry(id int64) {
 	}
 }
 
+func (c *channelMap) traceEvent(id int64, desc *TraceEventDesc) {
+	c.mu.Lock()
+	child := c.findEntry(id)
+	childTC, ok := child.(tracedChannel)
+	if !ok {
+		c.mu.Unlock()
+		return
+	}
+	childTC.getChannelTrace().append(&TraceEvent{Desc: desc.Desc, Severity: desc.Severity, Timestamp: time.Now()})
+	if desc.Parent != nil {
+		parent := c.findEntry(child.getParentID())
+		var chanType RefChannelType
+		switch child.(type) {
+		case *channel:
+			chanType = RefChannel
+		case *subChannel:
+			chanType = RefSubChannel
+		}
+		if parentTC, ok := parent.(tracedChannel); ok {
+			parentTC.getChannelTrace().append(&TraceEvent{
+				Desc:      desc.Parent.Desc,
+				Severity:  desc.Parent.Severity,
+				Timestamp: time.Now(),
+				RefID:     id,
+				RefName:   childTC.getRefName(),
+				RefType:   chanType,
+			})
+			childTC.incrTraceRefCount()
+		}
+	}
+	c.mu.Unlock()
+}
+
 type int64Slice []int64
 
 func (s int64Slice) Len() int           { return len(s) }
@@ -361,29 +452,32 @@ func copyMap(m map[int64]string) map[int64]string {
 	return n
 }
 
-func min(a, b int) int {
+func min(a, b int64) int64 {
 	if a < b {
 		return a
 	}
 	return b
 }
 
-func (c *channelMap) GetTopChannels(id int64) ([]*ChannelMetric, bool) {
+func (c *channelMap) GetTopChannels(id int64, maxResults int64) ([]*ChannelMetric, bool) {
+	if maxResults <= 0 {
+		maxResults = EntryPerPage
+	}
 	c.mu.RLock()
-	l := len(c.topLevelChannels)
+	l := int64(len(c.topLevelChannels))
 	ids := make([]int64, 0, l)
-	cns := make([]*channel, 0, min(l, EntryPerPage))
+	cns := make([]*channel, 0, min(l, maxResults))
 
 	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
+	count := int64(0)
 	var end bool
 	var t []*ChannelMetric
 	for i, v := range ids[idx:] {
-		if count == EntryPerPage {
+		if count == maxResults {
 			break
 		}
 		if cn, ok := c.channels[v]; ok {
@@ -408,25 +502,29 @@ func (c *channelMap) GetTopChannels(id int64) ([]*ChannelMetric, bool) {
 		t[i].ChannelData = cn.c.ChannelzMetric()
 		t[i].ID = cn.id
 		t[i].RefName = cn.refName
+		t[i].Trace = cn.trace.dumpData()
 	}
 	return t, end
 }
 
-func (c *channelMap) GetServers(id int64) ([]*ServerMetric, bool) {
+func (c *channelMap) GetServers(id, maxResults int64) ([]*ServerMetric, bool) {
+	if maxResults <= 0 {
+		maxResults = EntryPerPage
+	}
 	c.mu.RLock()
-	l := len(c.servers)
+	l := int64(len(c.servers))
 	ids := make([]int64, 0, l)
-	ss := make([]*server, 0, min(l, EntryPerPage))
+	ss := make([]*server, 0, min(l, maxResults))
 	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
+	count := int64(0)
 	var end bool
 	var s []*ServerMetric
 	for i, v := range ids[idx:] {
-		if count == EntryPerPage {
+		if count == maxResults {
 			break
 		}
 		if svr, ok := c.servers[v]; ok {
@@ -454,7 +552,10 @@ func (c *channelMap) GetServers(id int64) ([]*ServerMetric, bool) {
 	return s, end
 }
 
-func (c *channelMap) GetServerSockets(id int64, startID int64) ([]*SocketMetric, bool) {
+func (c *channelMap) GetServerSockets(id int64, startID int64, maxResults int64) ([]*SocketMetric, bool) {
+	if maxResults <= 0 {
+		maxResults = EntryPerPage
+	}
 	var svr *server
 	var ok bool
 	c.mu.RLock()
@@ -464,18 +565,18 @@ func (c *channelMap) GetServerSockets(id int64, startID int64) ([]*SocketMetric,
 		return nil, true
 	}
 	svrskts := svr.sockets
-	l := len(svrskts)
+	l := int64(len(svrskts))
 	ids := make([]int64, 0, l)
-	sks := make([]*normalSocket, 0, min(l, EntryPerPage))
+	sks := make([]*normalSocket, 0, min(l, maxResults))
 	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
+	sort.Sort(int64Slice(ids))
+	idx := sort.Search(len(ids), func(i int) bool { return ids[i] >= startID })
+	count := int64(0)
 	var end bool
 	for i, v := range ids[idx:] {
-		if count == EntryPerPage {
+		if count == maxResults {
 			break
 		}
 		if ns, ok := c.normalSockets[v]; ok {
@@ -514,10 +615,14 @@ func (c *channelMap) GetChannel(id int64) *ChannelMetric {
 	}
 	cm.NestedChans = copyMap(cn.nestedChans)
 	cm.SubChans = copyMap(cn.subChans)
+	// cn.c can be set to &dummyChannel{} when deleteSelfFromMap is called. Save a copy of cn.c when
+	// holding the lock to prevent potential data race.
+	chanCopy := cn.c
 	c.mu.RUnlock()
-	cm.ChannelData = cn.c.ChannelzMetric()
+	cm.ChannelData = chanCopy.ChannelzMetric()
 	cm.ID = cn.id
 	cm.RefName = cn.refName
+	cm.Trace = cn.trace.dumpData()
 	return cm
 }
 
@@ -532,10 +637,14 @@ func (c *channelMap) GetSubChannel(id int64) *SubChannelMetric {
 		return nil
 	}
 	cm.Sockets = copyMap(sc.sockets)
+	// sc.c can be set to &dummyChannel{} when deleteSelfFromMap is called. Save a copy of sc.c when
+	// holding the lock to prevent potential data race.
+	chanCopy := sc.c
 	c.mu.RUnlock()
-	cm.ChannelData = sc.c.ChannelzMetric()
+	cm.ChannelData = chanCopy.ChannelzMetric()
 	cm.ID = sc.id
 	cm.RefName = sc.refName
+	cm.Trace = sc.trace.dumpData()
 	return cm
 }
 
@@ -560,6 +669,23 @@ func (c *channelMap) GetSocket(id int64) *SocketMetric {
 	return nil
 }
 
+func (c *channelMap) GetServer(id int64) *ServerMetric {
+	sm := &ServerMetric{}
+	var svr *server
+	var ok bool
+	c.mu.RLock()
+	if svr, ok = c.servers[id]; !ok {
+		c.mu.RUnlock()
+		return nil
+	}
+	sm.ListenSockets = copyMap(svr.listenSockets)
+	c.mu.RUnlock()
+	sm.ID = svr.id
+	sm.RefName = svr.refName
+	sm.ServerData = svr.s.ChannelzMetric()
+	return sm
+}
+
 type idGenerator struct {
 	id int64
 }

vendor/google.golang.org/grpc/internal/channelz/types.go

@@ -20,9 +20,12 @@ package channelz
 
 import (
 	"net"
+	"sync"
+	"sync/atomic"
 	"time"
 
 	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/grpclog"
 )
 
@@ -39,6 +42,8 @@ type entry interface {
 	// 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()
+	// getParentID returns parent ID of the entry. 0 value parent ID means no parent.
+	getParentID() int64
 }
 
 // dummyEntry is a fake entry to handle entry not found case.
@@ -72,6 +77,10 @@ func (*dummyEntry) deleteSelfIfReady() {
 	// code should not reach here. deleteSelfIfReady is always called on an existing entry.
 }
 
+func (*dummyEntry) getParentID() int64 {
+	return 0
+}
+
 // ChannelMetric defines the info channelz provides for a specific Channel, which
 // includes ChannelInternalMetric and channelz-specific data, such as channelz id,
 // child list, etc.
@@ -94,6 +103,8 @@ type ChannelMetric struct {
 	// Note current grpc implementation doesn't allow channel having sockets directly,
 	// therefore, this is field is unused.
 	Sockets map[int64]string
+	// Trace contains the most recent traced events.
+	Trace *ChannelTrace
 }
 
 // SubChannelMetric defines the info channelz provides for a specific SubChannel,
@@ -120,6 +131,8 @@ type SubChannelMetric struct {
 	// 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
+	// Trace contains the most recent traced events.
+	Trace *ChannelTrace
 }
 
 // ChannelInternalMetric defines the struct that the implementor of Channel interface
@@ -137,7 +150,35 @@ type ChannelInternalMetric struct {
 	CallsFailed int64
 	// The last time a call was started on the channel.
 	LastCallStartedTimestamp time.Time
-	//TODO: trace
+}
+
+// ChannelTrace stores traced events on a channel/subchannel and related info.
+type ChannelTrace struct {
+	// EventNum is the number of events that ever got traced (i.e. including those that have been deleted)
+	EventNum int64
+	// CreationTime is the creation time of the trace.
+	CreationTime time.Time
+	// Events stores the most recent trace events (up to $maxTraceEntry, newer event will overwrite the
+	// oldest one)
+	Events []*TraceEvent
+}
+
+// TraceEvent represent a single trace event
+type TraceEvent struct {
+	// Desc is a simple description of the trace event.
+	Desc string
+	// Severity states the severity of this trace event.
+	Severity Severity
+	// Timestamp is the event time.
+	Timestamp time.Time
+	// RefID is the id of the entity that gets referenced in the event. RefID is 0 if no other entity is
+	// involved in this event.
+	// e.g. SubChannel (id: 4[]) Created. --> RefID = 4, RefName = "" (inside [])
+	RefID int64
+	// RefName is the reference name for the entity that gets referenced in the event.
+	RefName string
+	// RefType indicates the referenced entity type, i.e Channel or SubChannel.
+	RefType RefChannelType
 }
 
 // Channel is the interface that should be satisfied in order to be tracked by
@@ -146,6 +187,12 @@ type Channel interface {
 	ChannelzMetric() *ChannelInternalMetric
 }
 
+type dummyChannel struct{}
+
+func (d *dummyChannel) ChannelzMetric() *ChannelInternalMetric {
+	return &ChannelInternalMetric{}
+}
+
 type channel struct {
 	refName     string
 	c           Channel
@@ -155,6 +202,10 @@ type channel struct {
 	id          int64
 	pid         int64
 	cm          *channelMap
+	trace       *channelTrace
+	// traceRefCount is the number of trace events that reference this channel.
+	// Non-zero traceRefCount means the trace of this channel cannot be deleted.
+	traceRefCount int32
 }
 
 func (c *channel) addChild(id int64, e entry) {
@@ -179,25 +230,96 @@ func (c *channel) triggerDelete() {
 	c.deleteSelfIfReady()
 }
 
-func (c *channel) deleteSelfIfReady() {
+func (c *channel) getParentID() int64 {
+	return c.pid
+}
+
+// deleteSelfFromTree tries to delete the channel from the channelz entry relation tree, which means
+// deleting the channel reference from its parent's child list.
+//
+// In order for a channel to be deleted from the tree, it must meet the criteria that, removal of the
+// corresponding grpc object has been invoked, and the channel does not have any children left.
+//
+// The returned boolean value indicates whether the channel has been successfully deleted from tree.
+func (c *channel) deleteSelfFromTree() (deleted bool) {
 	if !c.closeCalled || len(c.subChans)+len(c.nestedChans) != 0 {
-		return
+		return false
 	}
-	c.cm.deleteEntry(c.id)
 	// not top channel
 	if c.pid != 0 {
 		c.cm.findEntry(c.pid).deleteChild(c.id)
 	}
+	return true
+}
+
+// deleteSelfFromMap checks whether it is valid to delete the channel from the map, which means
+// deleting the channel from channelz's tracking entirely. Users can no longer use id to query the
+// channel, and its memory will be garbage collected.
+//
+// The trace reference count of the channel must be 0 in order to be deleted from the map. This is
+// specified in the channel tracing gRFC that as long as some other trace has reference to an entity,
+// the trace of the referenced entity must not be deleted. In order to release the resource allocated
+// by grpc, the reference to the grpc object is reset to a dummy object.
+//
+// deleteSelfFromMap must be called after deleteSelfFromTree returns true.
+//
+// It returns a bool to indicate whether the channel can be safely deleted from map.
+func (c *channel) deleteSelfFromMap() (delete bool) {
+	if c.getTraceRefCount() != 0 {
+		c.c = &dummyChannel{}
+		return false
+	}
+	return true
+}
+
+// deleteSelfIfReady tries to delete the channel itself from the channelz database.
+// The delete process includes two steps:
+// 1. delete the channel from the entry relation tree, i.e. delete the channel reference from its
+//    parent's child list.
+// 2. delete the channel from the map, i.e. delete the channel entirely from channelz. Lookup by id
+//    will return entry not found error.
+func (c *channel) deleteSelfIfReady() {
+	if !c.deleteSelfFromTree() {
+		return
+	}
+	if !c.deleteSelfFromMap() {
+		return
+	}
+	c.cm.deleteEntry(c.id)
+	c.trace.clear()
+}
+
+func (c *channel) getChannelTrace() *channelTrace {
+	return c.trace
+}
+
+func (c *channel) incrTraceRefCount() {
+	atomic.AddInt32(&c.traceRefCount, 1)
+}
+
+func (c *channel) decrTraceRefCount() {
+	atomic.AddInt32(&c.traceRefCount, -1)
+}
+
+func (c *channel) getTraceRefCount() int {
+	i := atomic.LoadInt32(&c.traceRefCount)
+	return int(i)
+}
+
+func (c *channel) getRefName() string {
+	return c.refName
 }
 
 type subChannel struct {
-	refName     string
-	c           Channel
-	closeCalled bool
-	sockets     map[int64]string
-	id          int64
-	pid         int64
-	cm          *channelMap
+	refName       string
+	c             Channel
+	closeCalled   bool
+	sockets       map[int64]string
+	id            int64
+	pid           int64
+	cm            *channelMap
+	trace         *channelTrace
+	traceRefCount int32
 }
 
 func (sc *subChannel) addChild(id int64, e entry) {
@@ -218,12 +340,82 @@ func (sc *subChannel) triggerDelete() {
 	sc.deleteSelfIfReady()
 }
 
-func (sc *subChannel) deleteSelfIfReady() {
+func (sc *subChannel) getParentID() int64 {
+	return sc.pid
+}
+
+// deleteSelfFromTree tries to delete the subchannel from the channelz entry relation tree, which
+// means deleting the subchannel reference from its parent's child list.
+//
+// In order for a subchannel to be deleted from the tree, it must meet the criteria that, removal of
+// the corresponding grpc object has been invoked, and the subchannel does not have any children left.
+//
+// The returned boolean value indicates whether the channel has been successfully deleted from tree.
+func (sc *subChannel) deleteSelfFromTree() (deleted bool) {
 	if !sc.closeCalled || len(sc.sockets) != 0 {
+		return false
+	}
+	sc.cm.findEntry(sc.pid).deleteChild(sc.id)
+	return true
+}
+
+// deleteSelfFromMap checks whether it is valid to delete the subchannel from the map, which means
+// deleting the subchannel from channelz's tracking entirely. Users can no longer use id to query
+// the subchannel, and its memory will be garbage collected.
+//
+// The trace reference count of the subchannel must be 0 in order to be deleted from the map. This is
+// specified in the channel tracing gRFC that as long as some other trace has reference to an entity,
+// the trace of the referenced entity must not be deleted. In order to release the resource allocated
+// by grpc, the reference to the grpc object is reset to a dummy object.
+//
+// deleteSelfFromMap must be called after deleteSelfFromTree returns true.
+//
+// It returns a bool to indicate whether the channel can be safely deleted from map.
+func (sc *subChannel) deleteSelfFromMap() (delete bool) {
+	if sc.getTraceRefCount() != 0 {
+		// free the grpc struct (i.e. addrConn)
+		sc.c = &dummyChannel{}
+		return false
+	}
+	return true
+}
+
+// deleteSelfIfReady tries to delete the subchannel itself from the channelz database.
+// The delete process includes two steps:
+// 1. delete the subchannel from the entry relation tree, i.e. delete the subchannel reference from
+//    its parent's child list.
+// 2. delete the subchannel from the map, i.e. delete the subchannel entirely from channelz. Lookup
+//    by id will return entry not found error.
+func (sc *subChannel) deleteSelfIfReady() {
+	if !sc.deleteSelfFromTree() {
+		return
+	}
+	if !sc.deleteSelfFromMap() {
 		return
 	}
 	sc.cm.deleteEntry(sc.id)
-	sc.cm.findEntry(sc.pid).deleteChild(sc.id)
+	sc.trace.clear()
+}
+
+func (sc *subChannel) getChannelTrace() *channelTrace {
+	return sc.trace
+}
+
+func (sc *subChannel) incrTraceRefCount() {
+	atomic.AddInt32(&sc.traceRefCount, 1)
+}
+
+func (sc *subChannel) decrTraceRefCount() {
+	atomic.AddInt32(&sc.traceRefCount, -1)
+}
+
+func (sc *subChannel) getTraceRefCount() int {
+	i := atomic.LoadInt32(&sc.traceRefCount)
+	return int(i)
+}
+
+func (sc *subChannel) getRefName() string {
+	return sc.refName
 }
 
 // SocketMetric defines the info channelz provides for a specific Socket, which
@@ -281,9 +473,9 @@ type SocketInternalMetric struct {
 	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
+	RemoteName    string
+	SocketOptions *SocketOptionData
+	Security      credentials.ChannelzSecurityValue
 }
 
 // Socket is the interface that should be satisfied in order to be tracked by
@@ -317,6 +509,10 @@ func (ls *listenSocket) deleteSelfIfReady() {
 	grpclog.Errorf("cannot call deleteSelfIfReady on a listen socket")
 }
 
+func (ls *listenSocket) getParentID() int64 {
+	return ls.pid
+}
+
 type normalSocket struct {
 	refName string
 	s       Socket
@@ -342,6 +538,10 @@ func (ns *normalSocket) deleteSelfIfReady() {
 	grpclog.Errorf("cannot call deleteSelfIfReady on a normal socket")
 }
 
+func (ns *normalSocket) getParentID() int64 {
+	return ns.pid
+}
+
 // ServerMetric defines the info channelz provides for a specific Server, which
 // includes ServerInternalMetric and channelz-specific data, such as channelz id,
 // child list, etc.
@@ -369,7 +569,6 @@ type ServerInternalMetric struct {
 	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
@@ -416,3 +615,88 @@ func (s *server) deleteSelfIfReady() {
 	}
 	s.cm.deleteEntry(s.id)
 }
+
+func (s *server) getParentID() int64 {
+	return 0
+}
+
+type tracedChannel interface {
+	getChannelTrace() *channelTrace
+	incrTraceRefCount()
+	decrTraceRefCount()
+	getRefName() string
+}
+
+type channelTrace struct {
+	cm          *channelMap
+	createdTime time.Time
+	eventCount  int64
+	mu          sync.Mutex
+	events      []*TraceEvent
+}
+
+func (c *channelTrace) append(e *TraceEvent) {
+	c.mu.Lock()
+	if len(c.events) == getMaxTraceEntry() {
+		del := c.events[0]
+		c.events = c.events[1:]
+		if del.RefID != 0 {
+			// start recursive cleanup in a goroutine to not block the call originated from grpc.
+			go func() {
+				// need to acquire c.cm.mu lock to call the unlocked attemptCleanup func.
+				c.cm.mu.Lock()
+				c.cm.decrTraceRefCount(del.RefID)
+				c.cm.mu.Unlock()
+			}()
+		}
+	}
+	e.Timestamp = time.Now()
+	c.events = append(c.events, e)
+	c.eventCount++
+	c.mu.Unlock()
+}
+
+func (c *channelTrace) clear() {
+	c.mu.Lock()
+	for _, e := range c.events {
+		if e.RefID != 0 {
+			// caller should have already held the c.cm.mu lock.
+			c.cm.decrTraceRefCount(e.RefID)
+		}
+	}
+	c.mu.Unlock()
+}
+
+// Severity is the severity level of a trace event.
+// The canonical enumeration of all valid values is here:
+// https://github.com/grpc/grpc-proto/blob/9b13d199cc0d4703c7ea26c9c330ba695866eb23/grpc/channelz/v1/channelz.proto#L126.
+type Severity int
+
+const (
+	// CtUNKNOWN indicates unknown severity of a trace event.
+	CtUNKNOWN Severity = iota
+	// CtINFO indicates info level severity of a trace event.
+	CtINFO
+	// CtWarning indicates warning level severity of a trace event.
+	CtWarning
+	// CtError indicates error level severity of a trace event.
+	CtError
+)
+
+// RefChannelType is the type of the entity being referenced in a trace event.
+type RefChannelType int
+
+const (
+	// RefChannel indicates the referenced entity is a Channel.
+	RefChannel RefChannelType = iota
+	// RefSubChannel indicates the referenced entity is a SubChannel.
+	RefSubChannel
+)
+
+func (c *channelTrace) dumpData() *ChannelTrace {
+	c.mu.Lock()
+	ct := &ChannelTrace{EventNum: c.eventCount, CreationTime: c.createdTime}
+	ct.Events = c.events[:len(c.events)]
+	c.mu.Unlock()
+	return ct
+}

vendor/google.golang.org/grpc/internal/channelz/types_linux.go

@@ -0,0 +1,53 @@
+// +build !appengine
+
+/*
+ *
+ * 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 (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// SocketOptionData defines the struct to hold socket option data, and related
+// getter function to obtain info from fd.
+type SocketOptionData struct {
+	Linger      *unix.Linger
+	RecvTimeout *unix.Timeval
+	SendTimeout *unix.Timeval
+	TCPInfo     *unix.TCPInfo
+}
+
+// Getsockopt defines the function to get socket options requested by channelz.
+// It is to be passed to syscall.RawConn.Control().
+func (s *SocketOptionData) Getsockopt(fd uintptr) {
+	if v, err := unix.GetsockoptLinger(int(fd), syscall.SOL_SOCKET, syscall.SO_LINGER); err == nil {
+		s.Linger = v
+	}
+	if v, err := unix.GetsockoptTimeval(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVTIMEO); err == nil {
+		s.RecvTimeout = v
+	}
+	if v, err := unix.GetsockoptTimeval(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDTIMEO); err == nil {
+		s.SendTimeout = v
+	}
+	if v, err := unix.GetsockoptTCPInfo(int(fd), syscall.SOL_TCP, syscall.TCP_INFO); err == nil {
+		s.TCPInfo = v
+	}
+}

vendor/google.golang.org/grpc/internal/channelz/types_nonlinux.go

@@ -0,0 +1,44 @@
+// +build !linux appengine
+
+/*
+ *
+ * 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 (
+	"sync"
+
+	"google.golang.org/grpc/grpclog"
+)
+
+var once sync.Once
+
+// SocketOptionData defines the struct to hold socket option data, and related
+// getter function to obtain info from fd.
+// Windows OS doesn't support Socket Option
+type SocketOptionData struct {
+}
+
+// Getsockopt defines the function to get socket options requested by channelz.
+// It is to be passed to syscall.RawConn.Control().
+// Windows OS doesn't support Socket Option
+func (s *SocketOptionData) Getsockopt(fd uintptr) {
+	once.Do(func() {
+		grpclog.Warningln("Channelz: socket options are not supported on non-linux os and appengine.")
+	})
+}

vendor/google.golang.org/grpc/internal/channelz/util_linux.go

@@ -0,0 +1,39 @@
+// +build linux,!appengine
+
+/*
+ *
+ * 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 (
+	"syscall"
+)
+
+// GetSocketOption gets the socket option info of the conn.
+func GetSocketOption(socket interface{}) *SocketOptionData {
+	c, ok := socket.(syscall.Conn)
+	if !ok {
+		return nil
+	}
+	data := &SocketOptionData{}
+	if rawConn, err := c.SyscallConn(); err == nil {
+		rawConn.Control(data.Getsockopt)
+		return data
+	}
+	return nil
+}

vendor/google.golang.org/grpc/internal/channelz/util_nonlinux.go

@@ -0,0 +1,26 @@
+// +build !linux appengine
+
+/*
+ *
+ * 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
+
+// GetSocketOption gets the socket option info of the conn.
+func GetSocketOption(c interface{}) *SocketOptionData {
+	return nil
+}