Fresh dep ensure

vendor/google.golang.org/grpc/resolver_conn_wrapper.go

@@ -23,17 +23,19 @@ import (
 	"strings"
 
 	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal/channelz"
 	"google.golang.org/grpc/resolver"
 )
 
 // ccResolverWrapper is a wrapper on top of cc for resolvers.
 // It implements resolver.ClientConnection interface.
 type ccResolverWrapper struct {
-	cc       *ClientConn
-	resolver resolver.Resolver
-	addrCh   chan []resolver.Address
-	scCh     chan string
-	done     chan struct{}
+	cc                 *ClientConn
+	resolver           resolver.Resolver
+	addrCh             chan []resolver.Address
+	scCh               chan string
+	done               chan struct{}
+	lastAddressesCount int
 }
 
 // split2 returns the values from strings.SplitN(s, sep, 2).
@@ -114,6 +116,9 @@ func (ccr *ccResolverWrapper) watcher() {
 			default:
 			}
 			grpclog.Infof("ccResolverWrapper: sending new addresses to cc: %v", addrs)
+			if channelz.IsOn() {
+				ccr.addChannelzTraceEvent(addrs)
+			}
 			ccr.cc.handleResolvedAddrs(addrs, nil)
 		case sc := <-ccr.scCh:
 			select {
@@ -156,3 +161,29 @@ func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
 	}
 	ccr.scCh <- sc
 }
+
+func (ccr *ccResolverWrapper) addChannelzTraceEvent(addrs []resolver.Address) {
+	if len(addrs) == 0 && ccr.lastAddressesCount != 0 {
+		channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
+			Desc:     "Resolver returns an empty address list",
+			Severity: channelz.CtWarning,
+		})
+	} else if len(addrs) != 0 && ccr.lastAddressesCount == 0 {
+		var s string
+		for i, a := range addrs {
+			if a.ServerName != "" {
+				s += a.Addr + "(" + a.ServerName + ")"
+			} else {
+				s += a.Addr
+			}
+			if i != len(addrs)-1 {
+				s += " "
+			}
+		}
+		channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
+			Desc:     fmt.Sprintf("Resolver returns a non-empty address list (previous one was empty) %q", s),
+			Severity: channelz.CtINFO,
+		})
+	}
+	ccr.lastAddressesCount = len(addrs)
+}