From f6f9af4ee6945a24ecaa80203ac4307b0660bbe3 Mon Sep 17 00:00:00 2001
From: Menghan Li <menghanl@google.com>
Date: Fri, 4 Jun 2021 15:40:06 -0700
Subject: [PATCH 1/2] [c2p_id_random] c2p: add random number to xDS node ID in
 google-c2p resolver

---
 internal/grpcrand/grpcrand.go          | 8 ++++++++
 xds/googledirectpath/googlec2p.go      | 5 ++++-
 xds/googledirectpath/googlec2p_test.go | 2 +-
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/internal/grpcrand/grpcrand.go b/internal/grpcrand/grpcrand.go
index 200b115ca20..8d9c3975dc4 100644
--- a/internal/grpcrand/grpcrand.go
+++ b/internal/grpcrand/grpcrand.go
@@ -31,6 +31,14 @@ var (
 	mu sync.Mutex
 )
 
+// Int implements rand.Int on the grpcrand global source.
+func Int() int {
+	mu.Lock()
+	res := r.Int()
+	mu.Unlock()
+	return res
+}
+
 // Int63n implements rand.Int63n on the grpcrand global source.
 func Int63n(n int64) int64 {
 	mu.Lock()
diff --git a/xds/googledirectpath/googlec2p.go b/xds/googledirectpath/googlec2p.go
index b514f03bfbf..af487ec4a73 100644
--- a/xds/googledirectpath/googlec2p.go
+++ b/xds/googledirectpath/googlec2p.go
@@ -35,6 +35,7 @@ import (
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/internal/googlecloud"
 	internalgrpclog "google.golang.org/grpc/internal/grpclog"
+	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/internal/xds/env"
 	"google.golang.org/grpc/resolver"
 	_ "google.golang.org/grpc/xds" // To register xds resolvers and balancers.
@@ -152,13 +153,15 @@ var ipv6EnabledMetadata = &structpb.Struct{
 	},
 }
 
+var id = fmt.Sprintf("C2P-%d", grpcrand.Int())
+
 // newNode makes a copy of defaultNode, and populate it's Metadata and
 // Locality fields.
 func newNode(zone string, ipv6Capable bool) *v3corepb.Node {
 	ret := &v3corepb.Node{
 		// Not all required fields are set in defaultNote. Metadata will be set
 		// if ipv6 is enabled. Locality will be set to the value from metadata.
-		Id:                   "C2P",
+		Id:                   id,
 		UserAgentName:        gRPCUserAgentName,
 		UserAgentVersionType: &v3corepb.Node_UserAgentVersion{UserAgentVersion: grpc.Version},
 		ClientFeatures:       []string{clientFeatureNoOverprovisioning},
diff --git a/xds/googledirectpath/googlec2p_test.go b/xds/googledirectpath/googlec2p_test.go
index 5b8085ef34c..fb68fa23a1d 100644
--- a/xds/googledirectpath/googlec2p_test.go
+++ b/xds/googledirectpath/googlec2p_test.go
@@ -194,7 +194,7 @@ func TestBuildXDS(t *testing.T) {
 			}
 
 			wantNode := &v3corepb.Node{
-				Id:                   "C2P",
+				Id:                   id,
 				Metadata:             nil,
 				Locality:             &v3corepb.Locality{Zone: testZone},
 				UserAgentName:        gRPCUserAgentName,

From ce0f463c32373a56d7dbca5ddb0a7052b0eb3349 Mon Sep 17 00:00:00 2001
From: Menghan Li <menghanl@google.com>
Date: Mon, 7 Jun 2021 16:18:45 -0700
Subject: [PATCH 2/2] [c2p_id_random] c1

---
 internal/grpcrand/grpcrand.go | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/internal/grpcrand/grpcrand.go b/internal/grpcrand/grpcrand.go
index 8d9c3975dc4..7bc3583b5fc 100644
--- a/internal/grpcrand/grpcrand.go
+++ b/internal/grpcrand/grpcrand.go
@@ -34,31 +34,27 @@ var (
 // Int implements rand.Int on the grpcrand global source.
 func Int() int {
 	mu.Lock()
-	res := r.Int()
-	mu.Unlock()
-	return res
+	defer mu.Unlock()
+	return r.Int()
 }
 
 // Int63n implements rand.Int63n on the grpcrand global source.
 func Int63n(n int64) int64 {
 	mu.Lock()
-	res := r.Int63n(n)
-	mu.Unlock()
-	return res
+	defer mu.Unlock()
+	return r.Int63n(n)
 }
 
 // Intn implements rand.Intn on the grpcrand global source.
 func Intn(n int) int {
 	mu.Lock()
-	res := r.Intn(n)
-	mu.Unlock()
-	return res
+	defer mu.Unlock()
+	return r.Intn(n)
 }
 
 // Float64 implements rand.Float64 on the grpcrand global source.
 func Float64() float64 {
 	mu.Lock()
-	res := r.Float64()
-	mu.Unlock()
-	return res
+	defer mu.Unlock()
+	return r.Float64()
 }