HADOOP-18694. Client.Connection#updateAddress needs to ensure that address is resolved before updating (#5542). Contributed by dzcxzl.

Reviewed-by: Steve Vaughan <email@stevevaughan.me>
Reviewed-by: He Xiaoqiao <hexiaoqiao@apache.org>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -590,9 +590,8 @@ public class Client implements AutoCloseable {
       InetSocketAddress currentAddr = NetUtils.createSocketAddrForHost(
                                server.getHostName(), server.getPort());
 
-      if (!server.equals(currentAddr)) {
-        LOG.warn("Address change detected. Old: " + server.toString() +
-                                 " New: " + currentAddr.toString());
+      if (!currentAddr.isUnresolved() && !server.equals(currentAddr)) {
+        LOG.warn("Address change detected. Old: {} New: {}", server, currentAddr);
         server = currentAddr;
         // Update the remote address so that reconnections are with the updated address.
         // This avoids thrashing.

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestIPC.java

@@ -1728,6 +1728,47 @@ public class TestIPC {
     checkUserBinding(true);
   }
 
+  @Test(timeout=60000)
+  public void testUpdateAddressEnsureResolved() throws Exception {
+    // start server
+    Server server = new TestServer(1, false);
+    server.start();
+
+    SocketFactory mockFactory = Mockito.mock(SocketFactory.class);
+    doThrow(new ConnectTimeoutException("fake")).when(mockFactory)
+        .createSocket();
+    Client client = new Client(LongWritable.class, conf, mockFactory);
+    InetSocketAddress address =
+        new InetSocketAddress("localhost", NetUtils.getFreeSocketPort());
+    ConnectionId remoteId = getConnectionId(address, 100, conf);
+    try {
+      LambdaTestUtils.intercept(IOException.class, (Callable<Void>) () -> {
+        client.call(RpcKind.RPC_BUILTIN, new LongWritable(RANDOM.nextLong()),
+            remoteId, RPC.RPC_SERVICE_CLASS_DEFAULT, null);
+        return null;
+      });
+
+      assertFalse(address.isUnresolved());
+      assertFalse(remoteId.getAddress().isUnresolved());
+      assertEquals(System.identityHashCode(remoteId.getAddress()),
+          System.identityHashCode(address));
+
+      NetUtils.addStaticResolution("localhost", "host.invalid");
+      LambdaTestUtils.intercept(IOException.class, (Callable<Void>) () -> {
+        client.call(RpcKind.RPC_BUILTIN, new LongWritable(RANDOM.nextLong()),
+            remoteId, RPC.RPC_SERVICE_CLASS_DEFAULT, null);
+        return null;
+      });
+
+      assertFalse(remoteId.getAddress().isUnresolved());
+      assertEquals(System.identityHashCode(remoteId.getAddress()),
+          System.identityHashCode(address));
+    } finally {
+      client.stop();
+      server.stop();
+    }
+  }
+
   private void checkUserBinding(boolean asProxy) throws Exception {
     Socket s;
     // don't attempt bind with no service host.