YARN-11180. Fix CheckStyle.

Author: slfan1989

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java

@@ -669,14 +669,13 @@ public GetApplicationsResponse getApplications(GetApplicationsRequest request)
         federationFacade.getSubClusters(true);
     ClientMethod remoteMethod = new ClientMethod("getApplications",
         new Class[] {GetApplicationsRequest.class}, new Object[] {request});
-    Map<SubClusterId, GetApplicationsResponse> applications;
+    Map<SubClusterId, GetApplicationsResponse> applications = null;
     try {
       applications = invokeConcurrent(subclusters.keySet(), remoteMethod,
           GetApplicationsResponse.class);
     } catch (Exception ex) {
       routerMetrics.incrMultipleAppsFailedRetrieved();
-      LOG.error("Unable to get applications due to exception.", ex);
-      throw ex;
+      RouterServerUtil.logAndThrowException("Unable to get applications due to exception.", ex);
     }
     long stopTime = clock.getTime();
     routerMetrics.succeededMultipleAppsRetrieved(stopTime - startTime);
@@ -687,23 +686,23 @@ public GetApplicationsResponse getApplications(GetApplicationsRequest request)
   @Override
   public GetClusterMetricsResponse getClusterMetrics(
       GetClusterMetricsRequest request) throws YarnException, IOException {
+    if (request == null) {
+      routerMetrics.incrGetClusterMetricsFailedRetrieved();
+      RouterServerUtil.logAndThrowException("Missing getClusterMetrics request.", null);
+    }
     long startTime = clock.getTime();
-    Map<SubClusterId, SubClusterInfo> subclusters =
+    Map<SubClusterId, SubClusterInfo> subClusters =
         federationFacade.getSubClusters(true);
     ClientMethod remoteMethod = new ClientMethod("getClusterMetrics",
         new Class[] {GetClusterMetricsRequest.class}, new Object[] {request});
-    Map<SubClusterId, GetClusterMetricsResponse> clusterMetrics;
-
+    Map<SubClusterId, GetClusterMetricsResponse> clusterMetrics = null;
     try {
-      clusterMetrics = invokeConcurrent(subclusters.keySet(), remoteMethod,
+      clusterMetrics = invokeConcurrent(subClusters.keySet(), remoteMethod,
           GetClusterMetricsResponse.class);
-
     } catch (Exception ex) {
       routerMetrics.incrGetClusterMetricsFailedRetrieved();
-      LOG.error("Unable to get cluster metrics due to exception.", ex);
-      throw ex;
+      RouterServerUtil.logAndThrowException("Unable to get cluster metrics due to exception.", ex);
     }
-
     long stopTime = clock.getTime();
     routerMetrics.succeededGetClusterMetricsRetrieved(stopTime - startTime);
     return RouterYarnClientUtils.merge(clusterMetrics.values());

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/clientrm/TestFederationClientInterceptor.java

@@ -580,14 +580,14 @@ public void testGetApplicationAttemptEmptyRequest()
 
 
   @Test
-  public void testGetClusterMetricsRequest() throws YarnException, IOException {
+  public void testGetClusterMetricsRequest() throws Exception {
     LOG.info("Test FederationClientInterceptor : Get Cluster Metrics request");
     // null request
-    GetClusterMetricsResponse response = interceptor.getClusterMetrics(null);
-    Assert.assertEquals(subClusters.size(),
-        response.getClusterMetrics().getNumNodeManagers());
+    LambdaTestUtils.intercept(YarnException.class, "Missing getClusterMetrics request.",
+        () -> interceptor.getClusterMetrics(null));
+
     // normal request.
-    response =
+    GetClusterMetricsResponse response =
         interceptor.getClusterMetrics(GetClusterMetricsRequest.newInstance());
     Assert.assertEquals(subClusters.size(),
         response.getClusterMetrics().getNumNodeManagers());