From e51a17574f0d8dca331e479466f24e3aa3adef14 Mon Sep 17 00:00:00 2001
From: Chengyuan Zhang <chengyuanzhang@google.com>
Date: Mon, 7 Jun 2021 11:01:04 -0700
Subject: [PATCH] xds: append a random number to C2P generated node id (#8239)

Adding a random number to the xDS stream node id helps debugging for distinguishing between different clients.
---
 .../io/grpc/xds/GoogleCloudToProdNameResolver.java   | 12 ++++++++----
 .../grpc/xds/GoogleCloudToProdNameResolverTest.java  | 10 ++++++++--
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/xds/src/main/java/io/grpc/xds/GoogleCloudToProdNameResolver.java b/xds/src/main/java/io/grpc/xds/GoogleCloudToProdNameResolver.java
index 45d146e4a8..55ec809772 100644
--- a/xds/src/main/java/io/grpc/xds/GoogleCloudToProdNameResolver.java
+++ b/xds/src/main/java/io/grpc/xds/GoogleCloudToProdNameResolver.java
@@ -40,6 +40,7 @@ import java.net.HttpURLConnection;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.util.Random;
 import java.util.concurrent.Executor;
 
 /**
@@ -71,6 +72,7 @@ final class GoogleCloudToProdNameResolver extends NameResolver {
   private final Resource<Executor> executorResource;
   private final XdsClientPoolFactory xdsClientPoolFactory;
   private final NameResolver delegate;
+  private final Random rand;
   private final boolean usingExecutorResource;
   // It's not possible to use both PSM and DirectPath C2P in the same application.
   // Delegate to DNS if user-provided bootstrap is found.
@@ -83,15 +85,17 @@ final class GoogleCloudToProdNameResolver extends NameResolver {
 
   GoogleCloudToProdNameResolver(URI targetUri, Args args, Resource<Executor> executorResource,
       XdsClientPoolFactory xdsClientPoolFactory) {
-    this(targetUri, args, executorResource, xdsClientPoolFactory,
+    this(targetUri, args, executorResource, new Random(), xdsClientPoolFactory,
         NameResolverRegistry.getDefaultRegistry().asFactory());
   }
 
   @VisibleForTesting
   GoogleCloudToProdNameResolver(URI targetUri, Args args, Resource<Executor> executorResource,
-      XdsClientPoolFactory xdsClientPoolFactory, NameResolver.Factory nameResolverFactory) {
+      Random rand, XdsClientPoolFactory xdsClientPoolFactory,
+      NameResolver.Factory nameResolverFactory) {
     this.executorResource = checkNotNull(executorResource, "executorResource");
     this.xdsClientPoolFactory = checkNotNull(xdsClientPoolFactory, "xdsClientPoolFactory");
+    this.rand = checkNotNull(rand, "rand");
     String targetPath = checkNotNull(checkNotNull(targetUri, "targetUri").getPath(), "targetPath");
     Preconditions.checkArgument(
         targetPath.startsWith("/"),
@@ -169,9 +173,9 @@ final class GoogleCloudToProdNameResolver extends NameResolver {
     executor.execute(new Resolve());
   }
 
-  private static ImmutableMap<String, ?> generateBootstrap(String zone, boolean supportIpv6) {
+  private ImmutableMap<String, ?> generateBootstrap(String zone, boolean supportIpv6) {
     ImmutableMap.Builder<String, Object> nodeBuilder = ImmutableMap.builder();
-    nodeBuilder.put("id", "C2P");
+    nodeBuilder.put("id", "C2P-" + rand.nextInt());
     if (!zone.isEmpty()) {
       nodeBuilder.put("locality", ImmutableMap.of("zone", zone));
     }
diff --git a/xds/src/test/java/io/grpc/xds/GoogleCloudToProdNameResolverTest.java b/xds/src/test/java/io/grpc/xds/GoogleCloudToProdNameResolverTest.java
index 9df8953485..07e957b24c 100644
--- a/xds/src/test/java/io/grpc/xds/GoogleCloudToProdNameResolverTest.java
+++ b/xds/src/test/java/io/grpc/xds/GoogleCloudToProdNameResolverTest.java
@@ -47,6 +47,7 @@ import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Random;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicReference;
 import javax.annotation.Nullable;
@@ -103,6 +104,8 @@ public class GoogleCloudToProdNameResolverTest {
 
   @Mock
   private NameResolver.Listener2 mockListener;
+  @Mock
+  private Random mockRandom;
   @Captor
   private ArgumentCaptor<Status> errorCaptor;
   private boolean originalIsOnGcp;
@@ -111,6 +114,7 @@ public class GoogleCloudToProdNameResolverTest {
 
   @Before
   public void setUp() {
+    when(mockRandom.nextInt()).thenReturn(123456789);
     nsRegistry.register(new FakeNsProvider("dns"));
     nsRegistry.register(new FakeNsProvider("xds"));
     originalIsOnGcp = GoogleCloudToProdNameResolver.isOnGcp;
@@ -142,7 +146,8 @@ public class GoogleCloudToProdNameResolverTest {
       }
     };
     resolver = new GoogleCloudToProdNameResolver(
-        TARGET_URI, args, fakeExecutorResource, fakeXdsClientPoolFactory, nsRegistry.asFactory());
+        TARGET_URI, args, fakeExecutorResource, mockRandom, fakeXdsClientPoolFactory,
+        nsRegistry.asFactory());
     resolver.setHttpConnectionProvider(httpConnections);
   }
 
@@ -178,7 +183,8 @@ public class GoogleCloudToProdNameResolverTest {
     Map<String, ?> bootstrap = fakeXdsClientPoolFactory.bootstrapRef.get();
     Map<String, ?> node = (Map<String, ?>) bootstrap.get("node");
     assertThat(node).containsExactly(
-        "id", "C2P", "locality", ImmutableMap.of("zone", ZONE),
+        "id", "C2P-123456789",
+        "locality", ImmutableMap.of("zone", ZONE),
         "metadata", ImmutableMap.of("TRAFFICDIRECTOR_DIRECTPATH_C2P_IPV6_CAPABLE", true));
     Map<String, ?> server = Iterables.getOnlyElement(
         (List<Map<String, ?>>) bootstrap.get("xds_servers"));