YARN-6979. [Addendum patch] Fixed classname and added javadocs. (Kartheek Muthyala via asuresh)

(cherry picked from commit 7a82d7bcea8124e1b65c275fac15bf2047d17471)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/CMgrDecreaseContainersResourceEvent.java → hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/CMgrUpdateContainersEvent.java

@@ -21,17 +21,28 @@ package org.apache.hadoop.yarn.server.nodemanager;
 import org.apache.hadoop.yarn.api.records.Container;
 import java.util.List;
 
-public class CMgrDecreaseContainersResourceEvent extends ContainerManagerEvent {
+/**
+ * Event used by the NodeStatusUpdater to notify the ContainerManager of
+ * container update commands it received from the RM.
+ */
+public class CMgrUpdateContainersEvent extends ContainerManagerEvent {
 
-  private final List<Container> containersToDecrease;
+  private final List<Container> containersToUpdate;
 
-  public CMgrDecreaseContainersResourceEvent(List<Container>
-      containersToDecrease) {
-    super(ContainerManagerEventType.DECREASE_CONTAINERS_RESOURCE);
-    this.containersToDecrease = containersToDecrease;
+  /**
+   * Create event.
+   * @param containersToUpdate Container to update.
+   */
+  public CMgrUpdateContainersEvent(List<Container> containersToUpdate) {
+    super(ContainerManagerEventType.UPDATE_CONTAINERS);
+    this.containersToUpdate = containersToUpdate;
   }
 
-  public List<Container> getContainersToDecrease() {
-    return this.containersToDecrease;
+  /**
+   * Get containers to update.
+   * @return List of containers to update.
+   */
+  public List<Container> getContainersToUpdate() {
+    return this.containersToUpdate;
   }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/ContainerManagerEventType.java

@@ -21,6 +21,6 @@ package org.apache.hadoop.yarn.server.nodemanager;
 public enum ContainerManagerEventType {
   FINISH_APPS,
   FINISH_CONTAINERS,
-  DECREASE_CONTAINERS_RESOURCE,
+  UPDATE_CONTAINERS,
   SIGNAL_CONTAINERS
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/NodeStatusUpdaterImpl.java

@@ -834,12 +834,10 @@ public class NodeStatusUpdaterImpl extends AbstractService implements
                     parseCredentials(systemCredentials));
               }
               List<org.apache.hadoop.yarn.api.records.Container>
-                  containersToDecrease = response.getContainersToUpdate();
-              if (!containersToDecrease.isEmpty()) {
+                  containersToUpdate = response.getContainersToUpdate();
+              if (!containersToUpdate.isEmpty()) {
                 dispatcher.getEventHandler().handle(
-                    new CMgrDecreaseContainersResourceEvent(
-                        containersToDecrease)
-                );
+                    new CMgrUpdateContainersEvent(containersToUpdate));
               }
 
               // SignalContainer request originally comes from end users via

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/ContainerManagerImpl.java

@@ -95,7 +95,7 @@ import org.apache.hadoop.yarn.server.api.records.ContainerQueuingLimit;
 import org.apache.hadoop.yarn.server.api.records.OpportunisticContainersStatus;
 import org.apache.hadoop.yarn.server.nodemanager.CMgrCompletedAppsEvent;
 import org.apache.hadoop.yarn.server.nodemanager.CMgrCompletedContainersEvent;
-import org.apache.hadoop.yarn.server.nodemanager.CMgrDecreaseContainersResourceEvent;
+import org.apache.hadoop.yarn.server.nodemanager.CMgrUpdateContainersEvent;
 import org.apache.hadoop.yarn.server.nodemanager.CMgrSignalContainersEvent;
 import org.apache.hadoop.yarn.server.nodemanager.ContainerExecutor;
 import org.apache.hadoop.yarn.server.nodemanager.ContainerManagerEvent;
@@ -1512,11 +1512,11 @@ public class ContainerManagerImpl extends CompositeService implements
                   "Container Killed by ResourceManager"));
       }
       break;
-    case DECREASE_CONTAINERS_RESOURCE:
-      CMgrDecreaseContainersResourceEvent containersDecreasedEvent =
-          (CMgrDecreaseContainersResourceEvent) event;
+    case UPDATE_CONTAINERS:
+      CMgrUpdateContainersEvent containersDecreasedEvent =
+          (CMgrUpdateContainersEvent) event;
       for (org.apache.hadoop.yarn.api.records.Container container
-          : containersDecreasedEvent.getContainersToDecrease()) {
+          : containersDecreasedEvent.getContainersToUpdate()) {
         try {
           ContainerTokenIdentifier containerTokenIdentifier =
               BuilderUtils.newContainerTokenIdentifier(