1 files changed, 10 insertions, 1 deletions
diff --git a/vendor/google.golang.org/grpc/resolver/manual/manual.go b/vendor/google.golang.org/grpc/resolver/manual/manual.go
index f6e7b5ae3..f27978e12 100644
--- a/vendor/google.golang.org/grpc/resolver/manual/manual.go
+++ b/vendor/google.golang.org/grpc/resolver/manual/manual.go
@@ -21,6 +21,8 @@
 package manual
 
 import (
+	"sync"
+
 	"google.golang.org/grpc/resolver"
 )
 
@@ -50,6 +52,7 @@ type Resolver struct {
 	scheme        string
 
 	// Fields actually belong to the resolver.
+	mu             sync.Mutex // Guards access to CC.
 	CC             resolver.ClientConn
 	bootstrapState *resolver.State
 }
@@ -62,8 +65,10 @@ func (r *Resolver) InitialState(s resolver.State) {
 
 // Build returns itself for Resolver, because it's both a builder and a resolver.
 func (r *Resolver) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
-	r.BuildCallback(target, cc, opts)
+	r.mu.Lock()
 	r.CC = cc
+	r.mu.Unlock()
+	r.BuildCallback(target, cc, opts)
 	if r.bootstrapState != nil {
 		r.UpdateState(*r.bootstrapState)
 	}
@@ -87,10 +92,14 @@ func (r *Resolver) Close() {
 
 // UpdateState calls CC.UpdateState.
 func (r *Resolver) UpdateState(s resolver.State) {
+	r.mu.Lock()
 	r.CC.UpdateState(s)
+	r.mu.Unlock()
 }
 
 // ReportError calls CC.ReportError.
 func (r *Resolver) ReportError(err error) {
+	r.mu.Lock()
 	r.CC.ReportError(err)
+	r.mu.Unlock()
 }