HBASE-19474 Brought down the number of Checkstyle errors in hbase-zookeeper

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ClusterStatusTracker.java

@@ -20,11 +20,12 @@ package org.apache.hadoop.hbase.zookeeper;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.Abortable;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.zookeeper.KeeperException;
+
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.ZooKeeperProtos;
-import org.apache.zookeeper.KeeperException;
 
 /**
  * Tracker on cluster settings up in zookeeper.
@@ -42,8 +43,9 @@ public class ClusterStatusTracker extends ZKNodeTracker {
    *
    * <p>After construction, use {@link #start} to kick off tracking.
    *
-   * @param watcher
+   * @param watcher reference to the {@link ZKWatcher} which also contains configuration and
-   * @param abortable
+   *                constants
+   * @param abortable used to abort if a fatal error occurs
    */
   public ClusterStatusTracker(ZKWatcher watcher, Abortable abortable) {
     super(watcher, watcher.znodePaths.clusterStateZNode, abortable);
@@ -52,7 +54,7 @@ public class ClusterStatusTracker extends ZKNodeTracker {
   /**
    * Checks if cluster is up.
    * @return true if the cluster up ('shutdown' is its name up in zk) znode
-   * exists with data, false if not
+   *         exists with data, false if not
    */
   public boolean isClusterUp() {
     return super.getData(false) != null;
@@ -88,7 +90,7 @@ public class ClusterStatusTracker extends ZKNodeTracker {
 
   /**
    * @return Content of the clusterup znode as a serialized pb with the pb
-   * magic as prefix.
+   *         magic as prefix.
    */
   static byte [] toByteArray() {
     ZooKeeperProtos.ClusterUp.Builder builder =

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/EmptyWatcher.java

@@ -25,7 +25,7 @@ import org.apache.zookeeper.Watcher;
  * An empty ZooKeeper watcher
  */
 @InterfaceAudience.Private
-public class EmptyWatcher implements Watcher {
+public final class EmptyWatcher implements Watcher {
   // Used in this package but also by tests so needs to be public
   public static final EmptyWatcher instance = new EmptyWatcher();
   private EmptyWatcher() {}

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/HQuorumPeer.java

@@ -35,11 +35,11 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.HBaseInterfaceAudience;
 import org.apache.hadoop.hbase.HConstants;
-import org.apache.yetus.audience.InterfaceAudience;
-import org.apache.yetus.audience.InterfaceStability;
 import org.apache.hadoop.hbase.util.DNS;
 import org.apache.hadoop.hbase.util.Strings;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.yetus.audience.InterfaceStability;
 import org.apache.zookeeper.server.ServerConfig;
 import org.apache.zookeeper.server.ZooKeeperServerMain;
 import org.apache.zookeeper.server.quorum.QuorumPeerConfig;
@@ -54,7 +54,9 @@ import org.apache.zookeeper.server.quorum.QuorumPeerMain;
  */
 @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
 @InterfaceStability.Evolving
-public class HQuorumPeer {
+public final class HQuorumPeer {
+  private HQuorumPeer() {
+  }
 
   /**
    * Parse ZooKeeper configuration from HBase XML config and run a QuorumPeer.
@@ -80,7 +82,8 @@ public class HQuorumPeer {
     }
   }
 
-  private static void runZKServer(QuorumPeerConfig zkConfig) throws UnknownHostException, IOException {
+  private static void runZKServer(QuorumPeerConfig zkConfig)
+          throws UnknownHostException, IOException {
     if (zkConfig.isDistributed()) {
       QuorumPeerMain qp = new QuorumPeerMain();
       qp.runFromConfig(zkConfig);
@@ -139,8 +142,8 @@ public class HQuorumPeer {
     }
 
     // Set the max session timeout from the provided client-side timeout
-    properties.setProperty("maxSessionTimeout",
+    properties.setProperty("maxSessionTimeout", conf.get(HConstants.ZK_SESSION_TIMEOUT,
-      conf.get(HConstants.ZK_SESSION_TIMEOUT, Integer.toString(HConstants.DEFAULT_ZK_SESSION_TIMEOUT)));
+            Integer.toString(HConstants.DEFAULT_ZK_SESSION_TIMEOUT)));
 
     if (myId == -1) {
       throw new IOException("Could not find my address: " + myAddress +

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/LoadBalancerTracker.java

@@ -21,13 +21,14 @@ import java.io.IOException;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.zookeeper.KeeperException;
+
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.LoadBalancerProtos;
-import org.apache.hadoop.hbase.util.Bytes;
-import org.apache.zookeeper.KeeperException;
 
 /**
  * Tracks the load balancer state up in ZK
@@ -57,12 +58,14 @@ public class LoadBalancerTracker extends ZKNodeTracker {
   }
 
   /**
-   * Set the balancer on/off
+   * Set the balancer on/off.
-   * @param balancerOn
+   *
-   * @throws KeeperException
+   * @param balancerOn true if the balancher should be on, false otherwise
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public void setBalancerOn(boolean balancerOn) throws KeeperException {
-  byte [] upData = toByteArray(balancerOn);
+    byte [] upData = toByteArray(balancerOn);
+
     try {
       ZKUtil.setData(watcher, watcher.znodePaths.balancerZNode, upData);
     } catch(KeeperException.NoNodeException nne) {

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MasterAddressTracker.java

@@ -23,14 +23,15 @@ import java.io.InterruptedIOException;
 import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.ServerName;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.data.Stat;
+
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException;
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.ZooKeeperProtos;
-import org.apache.zookeeper.KeeperException;
-import org.apache.zookeeper.data.Stat;
-import org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException;
 
 /**
  * Manages the location of the current active Master for the RegionServer.
@@ -138,12 +139,12 @@ public class MasterAddressTracker extends ZKNodeTracker {
    * instance of this tracker in your context.
    * @param zkw ZKWatcher to use
    * @return ServerName stored in the the master address znode or null if no
-   * znode present.
+   *         znode present.
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
-   * @throws IOException
+   * @throws IOException if the address of the ZooKeeper master cannot be retrieved
    */
   public static ServerName getMasterAddress(final ZKWatcher zkw)
-  throws KeeperException, IOException {
+          throws KeeperException, IOException {
     byte [] data;
     try {
       data = ZKUtil.getData(zkw, zkw.znodePaths.masterAddressZNode);
@@ -169,13 +170,12 @@ public class MasterAddressTracker extends ZKNodeTracker {
    * instance of this tracker in your context.
    * @param zkw ZKWatcher to use
    * @return master info port in the the master address znode or null if no
-   * znode present.
+   *         znode present.
-   * // TODO can't return null for 'int' return type. non-static verison returns 0
+   *         // TODO can't return null for 'int' return type. non-static verison returns 0
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
-   * @throws IOException
+   * @throws IOException if the address of the ZooKeeper master cannot be retrieved
    */
-  public static int getMasterInfoPort(final ZKWatcher zkw) throws KeeperException,
+  public static int getMasterInfoPort(final ZKWatcher zkw) throws KeeperException, IOException {
-      IOException {
     byte[] data;
     try {
       data = ZKUtil.getData(zkw, zkw.znodePaths.masterAddressZNode);
@@ -201,10 +201,10 @@ public class MasterAddressTracker extends ZKNodeTracker {
    * path.
    * @param zkw The ZKWatcher to use.
    * @param znode Where to create the znode; could be at the top level or it
-   * could be under backup masters
+   *              could be under backup masters
    * @param master ServerName of the current master must not be null.
    * @return true if node created, false if not; a watch is set in both cases
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static boolean setMasterAddress(final ZKWatcher zkw,
       final String znode, final ServerName master, int infoPort)
@@ -223,7 +223,7 @@ public class MasterAddressTracker extends ZKNodeTracker {
   /**
    * @param sn must not be null
    * @return Content of the master znode as a serialized pb with the pb
-   * magic as prefix.
+   *         magic as prefix.
    */
   static byte[] toByteArray(final ServerName sn, int infoPort) {
     ZooKeeperProtos.Master.Builder mbuilder = ZooKeeperProtos.Master.newBuilder();
@@ -240,7 +240,7 @@ public class MasterAddressTracker extends ZKNodeTracker {
   /**
    * @param data zookeeper data. may be null
    * @return pb object of master, null if no active master
-   * @throws DeserializationException
+   * @throws DeserializationException if the parsing fails
    */
   public static ZooKeeperProtos.Master parse(byte[] data) throws DeserializationException {
     if (data == null) {

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MetaTableLocator.java

@@ -99,9 +99,10 @@ public class MetaTableLocator {
   }
 
   /**
+   * Gets the meta regions and their locations for the given path and replica ID.
    *
-   * @param zkw
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @param replicaId
+   * @param replicaId the ID of the replica
    * @return meta table regions and their locations.
    */
   public List<Pair<RegionInfo, ServerName>> getMetaRegionsAndLocations(ZKWatcher zkw,
@@ -114,6 +115,8 @@ public class MetaTableLocator {
   }
 
   /**
+   * Gets the meta regions for the given path with the default replica ID.
+   *
    * @param zkw ZooKeeper watcher to be used
    * @return List of meta regions
    */
@@ -122,9 +125,10 @@ public class MetaTableLocator {
   }
 
   /**
+   * Gets the meta regions for the given path and replica ID.
    *
-   * @param zkw
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @param replicaId
+   * @param replicaId the ID of the replica
    * @return List of meta regions
    */
   public List<RegionInfo> getMetaRegions(ZKWatcher zkw, int replicaId) {
@@ -133,9 +137,11 @@ public class MetaTableLocator {
     return getListOfRegionInfos(result);
   }
 
-  private List<RegionInfo> getListOfRegionInfos(
+  private List<RegionInfo> getListOfRegionInfos(final List<Pair<RegionInfo, ServerName>> pairs) {
-      final List<Pair<RegionInfo, ServerName>> pairs) {
+    if (pairs == null || pairs.isEmpty()) {
-    if (pairs == null || pairs.isEmpty()) return Collections.EMPTY_LIST;
+      return Collections.EMPTY_LIST;
+    }
+
     List<RegionInfo> result = new ArrayList<>(pairs.size());
     for (Pair<RegionInfo, ServerName> pair: pairs) {
       result.add(pair.getFirst());
@@ -159,8 +165,8 @@ public class MetaTableLocator {
 
   /**
    * Gets the meta region location, if available.  Does not block.
-   * @param zkw
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @param replicaId
+   * @param replicaId the ID of the replica
    * @return server name
    */
   public ServerName getMetaRegionLocation(final ZKWatcher zkw, int replicaId) {
@@ -177,12 +183,13 @@ public class MetaTableLocator {
    * specified timeout if not immediately available.
    * Given the zookeeper notification could be delayed, we will try to
    * get the latest data.
-   * @param zkw
+   *
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
    * @param timeout maximum time to wait, in millis
    * @return server name for server hosting meta region formatted as per
    * {@link ServerName}, or null if none available
    * @throws InterruptedException if interrupted while waiting
-   * @throws NotAllMetaRegionsOnlineException
+   * @throws NotAllMetaRegionsOnlineException if a meta or root region is not online
    */
   public ServerName waitMetaRegionLocation(ZKWatcher zkw, long timeout)
   throws InterruptedException, NotAllMetaRegionsOnlineException {
@@ -190,17 +197,17 @@ public class MetaTableLocator {
   }
 
   /**
-   * Gets the meta region location, if available, and waits for up to the
+   * Gets the meta region location, if available, and waits for up to the specified timeout if not
-   * specified timeout if not immediately available.
+   * immediately available. Given the zookeeper notification could be delayed, we will try to
-   * Given the zookeeper notification could be delayed, we will try to
    * get the latest data.
-   * @param zkw
+   *
-   * @param replicaId
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
+   * @param replicaId the ID of the replica
    * @param timeout maximum time to wait, in millis
    * @return server name for server hosting meta region formatted as per
    * {@link ServerName}, or null if none available
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
-   * @throws NotAllMetaRegionsOnlineException
+   * @throws NotAllMetaRegionsOnlineException if a meta or root region is not online
    */
   public ServerName waitMetaRegionLocation(ZKWatcher zkw, int replicaId, long timeout)
   throws InterruptedException, NotAllMetaRegionsOnlineException {
@@ -234,7 +241,10 @@ public class MetaTableLocator {
     long startTime = System.currentTimeMillis();
     while (!stopped) {
       try {
-        if (waitMetaRegionLocation(zkw, 100) != null) break;
+        if (waitMetaRegionLocation(zkw, 100) != null) {
+          break;
+        }
+
         long sleepTime = System.currentTimeMillis() - startTime;
         // +1 in case sleepTime=0
         if ((sleepTime + 1) % 10000 == 0) {
@@ -251,33 +261,33 @@ public class MetaTableLocator {
 
   /**
    * Verify <code>hbase:meta</code> is deployed and accessible.
-   * @param hConnection
+   *
-   * @param zkw
+   * @param hConnection the connection to use
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
    * @param timeout How long to wait on zk for meta address (passed through to
-   * the internal call to {@link #getMetaServerConnection}.
+   *                the internal call to {@link #getMetaServerConnection}.
    * @return True if the <code>hbase:meta</code> location is healthy.
-   * @throws java.io.IOException
+   * @throws IOException if the number of retries for getting the connection is exceeded
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
    */
-  public boolean verifyMetaRegionLocation(ClusterConnection hConnection,
+  public boolean verifyMetaRegionLocation(ClusterConnection hConnection, ZKWatcher zkw,
-                                          ZKWatcher zkw, final long timeout)
+      final long timeout) throws InterruptedException, IOException {
-  throws InterruptedException, IOException {
     return verifyMetaRegionLocation(hConnection, zkw, timeout, RegionInfo.DEFAULT_REPLICA_ID);
   }
 
   /**
    * Verify <code>hbase:meta</code> is deployed and accessible.
-   * @param connection
+   *
-   * @param zkw
+   * @param connection the connection to use
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
    * @param timeout How long to wait on zk for meta address (passed through to
-   * @param replicaId
+   * @param replicaId the ID of the replica
    * @return True if the <code>hbase:meta</code> location is healthy.
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
-   * @throws IOException
+   * @throws IOException if the number of retries for getting the connection is exceeded
    */
-  public boolean verifyMetaRegionLocation(ClusterConnection connection,
+  public boolean verifyMetaRegionLocation(ClusterConnection connection, ZKWatcher zkw,
-                                          ZKWatcher zkw, final long timeout, int replicaId)
+      final long timeout, int replicaId) throws InterruptedException, IOException {
-  throws InterruptedException, IOException {
     AdminProtos.AdminService.BlockingInterface service = null;
     try {
       service = getMetaServerConnection(connection, zkw, timeout, replicaId);
@@ -299,12 +309,10 @@ public class MetaTableLocator {
    * Verify we can connect to <code>hostingServer</code> and that its carrying
    * <code>regionName</code>.
    * @param hostingServer Interface to the server hosting <code>regionName</code>
-   * @param address The servername that goes with the <code>metaServer</code>
+   * @param address The servername that goes with the <code>metaServer</code> interface.
-   * Interface.  Used logging.
+   *                Used logging.
    * @param regionName The regionname we are interested in.
-   * @return True if we were able to verify the region located at other side of
+   * @return True if we were able to verify the region located at other side of the interface.
-   * the Interface.
-   * @throws IOException
    */
   // TODO: We should be able to get the ServerName from the AdminProtocol
   // rather than have to pass it in.  Its made awkward by the fact that the
@@ -312,8 +320,7 @@ public class MetaTableLocator {
   // to be fixed to go to a local method or to a cache before we can do this.
   private boolean verifyRegionLocation(final ClusterConnection connection,
       AdminService.BlockingInterface hostingServer, final ServerName address,
-      final byte [] regionName)
+      final byte [] regionName) {
-  throws IOException {
     if (hostingServer == null) {
       LOG.info("Passed hostingServer is null");
       return false;
@@ -347,34 +354,33 @@ public class MetaTableLocator {
   }
 
   /**
-   * Gets a connection to the server hosting meta, as reported by ZooKeeper,
+   * Gets a connection to the server hosting meta, as reported by ZooKeeper, waiting up to the
-   * waiting up to the specified timeout for availability.
+   * specified timeout for availability.
+   *
    * <p>WARNING: Does not retry.  Use an {@link org.apache.hadoop.hbase.client.HTable} instead.
-   * @param connection
+   *
-   * @param zkw
+   * @param connection the connection to use
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
    * @param timeout How long to wait on meta location
-   * @param replicaId
+   * @param replicaId the ID of the replica
    * @return connection to server hosting meta
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
-   * @throws NotAllMetaRegionsOnlineException if timed out waiting
+   * @throws IOException if the number of retries for getting the connection is exceeded
-   * @throws IOException
    */
   private AdminService.BlockingInterface getMetaServerConnection(ClusterConnection connection,
-                                                                 ZKWatcher zkw, long timeout, int replicaId)
+      ZKWatcher zkw, long timeout, int replicaId) throws InterruptedException, IOException {
-  throws InterruptedException, NotAllMetaRegionsOnlineException, IOException {
     return getCachedConnection(connection, waitMetaRegionLocation(zkw, replicaId, timeout));
   }
 
   /**
    * @param sn ServerName to get a connection against.
    * @return The AdminProtocol we got when we connected to <code>sn</code>
-   * May have come from cache, may not be good, may have been setup by this
+   *         May have come from cache, may not be good, may have been setup by this invocation, or
-   * invocation, or may be null.
+   *         may be null.
-   * @throws IOException
+   * @throws IOException if the number of retries for getting the connection is exceeded
    */
   private static AdminService.BlockingInterface getCachedConnection(ClusterConnection connection,
-    ServerName sn)
+      ServerName sn) throws IOException {
-  throws IOException {
     if (sn == null) {
       return null;
     }
@@ -430,16 +436,16 @@ public class MetaTableLocator {
   }
 
   /**
-   * Sets the location of <code>hbase:meta</code> in ZooKeeper to the
+   * Sets the location of <code>hbase:meta</code> in ZooKeeper to the specified server address.
-   * specified server address.
+   * @param zookeeper reference to the {@link ZKWatcher} which also contains configuration and
-   * @param zookeeper
+   *                  operation
-   * @param serverName
+   * @param serverName the name of the server
-   * @param replicaId
+   * @param replicaId the ID of the replica
-   * @param state
+   * @param state the state of the region
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
-  public static void setMetaLocation(ZKWatcher zookeeper,
+  public static void setMetaLocation(ZKWatcher zookeeper, ServerName serverName, int replicaId,
-      ServerName serverName, int replicaId, RegionState.State state) throws KeeperException {
+      RegionState.State state) throws KeeperException {
     if (serverName == null) {
       LOG.warn("Tried to set null ServerName in hbase:meta; skipping -- ServerName required");
       return;
@@ -476,13 +482,14 @@ public class MetaTableLocator {
 
   /**
    * Load the meta region state from the meta server ZNode.
-   * @param zkw
+   *
-   * @param replicaId
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
+   * @param replicaId the ID of the replica
    * @return regionstate
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static RegionState getMetaRegionState(ZKWatcher zkw, int replicaId)
-      throws KeeperException {
+          throws KeeperException {
     RegionState.State state = RegionState.State.OPEN;
     ServerName serverName = null;
     try {
@@ -491,8 +498,8 @@ public class MetaTableLocator {
         try {
           int prefixLen = ProtobufUtil.lengthOfPBMagic();
           ZooKeeperProtos.MetaRegionServer rl =
-            ZooKeeperProtos.MetaRegionServer.PARSER.parseFrom
+            ZooKeeperProtos.MetaRegionServer.PARSER.parseFrom(data, prefixLen,
-              (data, prefixLen, data.length - prefixLen);
+                    data.length - prefixLen);
           if (rl.hasState()) {
             state = RegionState.State.convert(rl.getState());
           }
@@ -545,24 +552,28 @@ public class MetaTableLocator {
     }
   }
   /**
-   * Wait until the primary meta region is available. Get the secondary
+   * Wait until the primary meta region is available. Get the secondary locations as well but don't
-   * locations as well but don't block for those.
+   * block for those.
-   * @param zkw
+   *
-   * @param timeout
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @param conf
+   * @param timeout maximum time to wait in millis
+   * @param conf the {@link Configuration} to use
    * @return ServerName or null if we timed out.
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
    */
-  public List<ServerName> blockUntilAvailable(final ZKWatcher zkw,
+  public List<ServerName> blockUntilAvailable(final ZKWatcher zkw, final long timeout,
-      final long timeout, Configuration conf)
+      Configuration conf) throws InterruptedException {
-          throws InterruptedException {
     int numReplicasConfigured = 1;
 
     List<ServerName> servers = new ArrayList<>();
     // Make the blocking call first so that we do the wait to know
     // the znodes are all in place or timeout.
     ServerName server = blockUntilAvailable(zkw, timeout);
-    if (server == null) return null;
+
+    if (server == null) {
+      return null;
+    }
+
     servers.add(server);
 
     try {
@@ -583,27 +594,32 @@ public class MetaTableLocator {
    * @param zkw zookeeper connection to use
    * @param timeout maximum time to wait, in millis
    * @return ServerName or null if we timed out.
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
    */
-  public ServerName blockUntilAvailable(final ZKWatcher zkw,
+  public ServerName blockUntilAvailable(final ZKWatcher zkw, final long timeout)
-      final long timeout)
+          throws InterruptedException {
-  throws InterruptedException {
     return blockUntilAvailable(zkw, RegionInfo.DEFAULT_REPLICA_ID, timeout);
   }
 
   /**
    * Wait until the meta region is available and is not in transition.
-   * @param zkw
+   *
-   * @param replicaId
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and constants
-   * @param timeout
+   * @param replicaId the ID of the replica
+   * @param timeout maximum time to wait in millis
    * @return ServerName or null if we timed out.
-   * @throws InterruptedException
+   * @throws InterruptedException if waiting for the socket operation fails
    */
-  public ServerName blockUntilAvailable(final ZKWatcher zkw, int replicaId,
+  public ServerName blockUntilAvailable(final ZKWatcher zkw, int replicaId, final long timeout)
-                                        final long timeout)
+          throws InterruptedException {
-  throws InterruptedException {
+    if (timeout < 0) {
-    if (timeout < 0) throw new IllegalArgumentException();
+      throw new IllegalArgumentException();
-    if (zkw == null) throw new IllegalArgumentException();
+    }
+
+    if (zkw == null) {
+      throw new IllegalArgumentException();
+    }
+
     long startTime = System.currentTimeMillis();
     ServerName sn = null;
     while (true) {

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/MiniZooKeeperCluster.java

@@ -20,9 +20,9 @@ package org.apache.hadoop.hbase.zookeeper;
 
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.InterruptedIOException;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.InterruptedIOException;
 import java.io.OutputStream;
 import java.io.Reader;
 import java.net.BindException;
@@ -34,9 +34,9 @@ import java.util.Random;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HConstants;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.server.NIOServerCnxnFactory;
 import org.apache.zookeeper.server.ZooKeeperServer;
 import org.apache.zookeeper.server.persistence.FileTxnLog;
@@ -187,17 +187,18 @@ public class MiniZooKeeperCluster {
   }
 
   /**
-   * @param baseDir
+   * @param baseDir the base directory to use
-   * @param numZooKeeperServers
+   * @param numZooKeeperServers the number of ZooKeeper servers
-   * @return ClientPort server bound to, -1 if there was a
+   * @return ClientPort server bound to, -1 if there was a binding problem and we couldn't pick
-   *         binding problem and we couldn't pick another port.
+   *         another port.
-   * @throws IOException
+   * @throws IOException if an operation fails during the startup
-   * @throws InterruptedException
+   * @throws InterruptedException if the startup fails
    */
   public int startup(File baseDir, int numZooKeeperServers) throws IOException,
-      InterruptedException {
+          InterruptedException {
-    if (numZooKeeperServers <= 0)
+    if (numZooKeeperServers <= 0) {
       return -1;
+    }
 
     setupTestEnv();
     shutdown();
@@ -226,15 +227,18 @@ public class MiniZooKeeperCluster {
 
       ZooKeeperServer server = new ZooKeeperServer(dir, dir, tickTimeToUse);
       // Setting {min,max}SessionTimeout defaults to be the same as in Zookeeper
-      server.setMinSessionTimeout(configuration.getInt("hbase.zookeeper.property.minSessionTimeout", -1));
+      server.setMinSessionTimeout(configuration.getInt(
-      server.setMaxSessionTimeout(configuration.getInt("hbase.zookeeper.property.maxSessionTimeout", -1));
+              "hbase.zookeeper.property.minSessionTimeout", -1));
+      server.setMaxSessionTimeout(configuration.getInt(
+              "hbase.zookeeper.property.maxSessionTimeout", -1));
       NIOServerCnxnFactory standaloneServerFactory;
       while (true) {
         try {
           standaloneServerFactory = new NIOServerCnxnFactory();
           standaloneServerFactory.configure(
             new InetSocketAddress(currentClientPort),
-            configuration.getInt(HConstants.ZOOKEEPER_MAX_CLIENT_CNXNS, HConstants.DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS));
+            configuration.getInt(HConstants.ZOOKEEPER_MAX_CLIENT_CNXNS,
+                    HConstants.DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS));
         } catch (BindException e) {
           LOG.debug("Failed binding ZK Server to client port: " +
               currentClientPort, e);
@@ -290,7 +294,7 @@ public class MiniZooKeeperCluster {
   }
 
   /**
-   * @throws IOException
+   * @throws IOException if waiting for the shutdown of a server fails
    */
   public void shutdown() throws IOException {
     // shut down all the zk servers
@@ -321,13 +325,12 @@ public class MiniZooKeeperCluster {
     }
   }
 
-  /**@return clientPort return clientPort if there is another ZK backup can run
+  /**
+   * @return clientPort return clientPort if there is another ZK backup can run
    *         when killing the current active; return -1, if there is no backups.
-   * @throws IOException
+   * @throws IOException if waiting for the shutdown of a server fails
-   * @throws InterruptedException
    */
-  public int killCurrentActiveZooKeeperServer() throws IOException,
+  public int killCurrentActiveZooKeeperServer() throws IOException, InterruptedException {
-                                        InterruptedException {
     if (!started || activeZKServerIndex < 0) {
       return -1;
     }
@@ -363,14 +366,12 @@ public class MiniZooKeeperCluster {
   }
 
   /**
-   * Kill one back up ZK servers
+   * Kill one back up ZK servers.
-   * @throws IOException
+   *
-   * @throws InterruptedException
+   * @throws IOException if waiting for the shutdown of a server fails
    */
-  public void killOneBackupZooKeeperServer() throws IOException,
+  public void killOneBackupZooKeeperServer() throws IOException, InterruptedException {
-                                        InterruptedException {
+    if (!started || activeZKServerIndex < 0 || standaloneServerFactoryList.size() <= 1) {
-    if (!started || activeZKServerIndex < 0 ||
-        standaloneServerFactoryList.size() <= 1) {
       return ;
     }
 

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/RecoverableZooKeeper.java

@@ -26,13 +26,13 @@ import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.hbase.trace.TraceUtil;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.RetryCounter;
 import org.apache.hadoop.hbase.util.RetryCounterFactory;
-import org.apache.yetus.audience.InterfaceAudience;
-import org.apache.hadoop.hbase.trace.TraceUtil;
 import org.apache.htrace.core.TraceScope;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.AsyncCallback;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.KeeperException;
@@ -113,14 +113,19 @@ public class RecoverableZooKeeper {
     this.sessionTimeout = sessionTimeout;
     this.quorumServers = quorumServers;
     this.metrics = new ZKMetrics();
-    try {checkZk();} catch (Exception x) {/* ignore */}
+
+    try {
+      checkZk();
+    } catch (Exception x) {
+      /* ignore */
+    }
   }
 
   /**
    * Try to create a ZooKeeper connection. Turns any exception encountered into a
    * KeeperException.OperationTimeoutException so it can retried.
    * @return The created ZooKeeper connection object
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   protected synchronized ZooKeeper checkZk() throws KeeperException {
     if (this.zk == null) {
@@ -161,7 +166,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           checkZk().delete(path, version);
-          this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerWriteOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -205,7 +211,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           Stat nodeStat = checkZk().exists(path, watcher);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime, 1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime, 1));
           return nodeStat;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -239,7 +246,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           Stat nodeStat = checkZk().exists(path, watch);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return nodeStat;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -285,7 +293,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           List<String> children = checkZk().getChildren(path, watcher);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return children;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -320,7 +329,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           List<String> children = checkZk().getChildren(path, watch);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return children;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -355,7 +365,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           byte[] revData = checkZk().getData(path, watcher, stat);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return ZKMetadata.removeMetaData(revData);
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -390,7 +401,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           byte[] revData = checkZk().getData(path, watch, stat);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return ZKMetadata.removeMetaData(revData);
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -430,7 +442,8 @@ public class RecoverableZooKeeper {
         try {
           startTime = EnvironmentEdgeManager.currentTime();
           Stat nodeStat = checkZk().setData(path, newData, version);
-          this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerWriteOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return nodeStat;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -450,7 +463,8 @@ public class RecoverableZooKeeper {
                   Stat stat = new Stat();
                   startTime = EnvironmentEdgeManager.currentTime();
                   byte[] revData = checkZk().getData(path, false, stat);
-                  this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+                  this.metrics.registerReadOperationLatency(
+                          Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
                   if(Bytes.compareTo(revData, newData) == 0) {
                     // the bad version is caused by previous successful setData
                     return stat;
@@ -484,7 +498,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           List<ACL> nodeACL = checkZk().getACL(path, stat);
-          this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerReadOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return nodeACL;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -519,7 +534,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           Stat nodeStat = checkZk().setACL(path, acls, version);
-          this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerWriteOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return nodeStat;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -587,7 +603,8 @@ public class RecoverableZooKeeper {
       try {
         startTime = EnvironmentEdgeManager.currentTime();
         String nodePath = checkZk().create(path, data, acl, createMode);
-        this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+        this.metrics.registerWriteOperationLatency(
+                Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
         return nodePath;
       } catch (KeeperException e) {
         this.metrics.registerFailedZKCall();
@@ -599,7 +616,8 @@ public class RecoverableZooKeeper {
               // so we read the node and compare.
               startTime = EnvironmentEdgeManager.currentTime();
               byte[] currentData = checkZk().getData(path, false, null);
-              this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+              this.metrics.registerReadOperationLatency(
+                      Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
               if (currentData != null &&
                   Bytes.compareTo(currentData, data) == 0) {
                 // We successfully created a non-sequential node
@@ -649,7 +667,8 @@ public class RecoverableZooKeeper {
         first = false;
         long startTime = EnvironmentEdgeManager.currentTime();
         String nodePath = checkZk().create(newPath, data, acl, createMode);
-        this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+        this.metrics.registerWriteOperationLatency(
+                Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
         return nodePath;
       } catch (KeeperException e) {
         this.metrics.registerFailedZKCall();
@@ -674,9 +693,10 @@ public class RecoverableZooKeeper {
    * Convert Iterable of {@link org.apache.zookeeper.Op} we got into the ZooKeeper.Op
    * instances to actually pass to multi (need to do this in order to appendMetaData).
    */
-  private Iterable<Op> prepareZKMulti(Iterable<Op> ops)
+  private Iterable<Op> prepareZKMulti(Iterable<Op> ops) throws UnsupportedOperationException {
-  throws UnsupportedOperationException {
+    if(ops == null) {
-    if(ops == null) return null;
+      return null;
+    }
 
     List<Op> preparedOps = new LinkedList<>();
     for (Op op : ops) {
@@ -689,8 +709,8 @@ public class RecoverableZooKeeper {
         preparedOps.add(op);
       } else if (op.getType() == ZooDefs.OpCode.setData) {
         SetDataRequest setData = (SetDataRequest)op.toRequestRecord();
-        preparedOps.add(Op.setData(setData.getPath(), ZKMetadata.appendMetaData(id, setData.getData()),
+        preparedOps.add(Op.setData(setData.getPath(),
-          setData.getVersion()));
+                ZKMetadata.appendMetaData(id, setData.getData()), setData.getVersion()));
       } else {
         throw new UnsupportedOperationException("Unexpected ZKOp type: " + op.getClass().getName());
       }
@@ -710,7 +730,8 @@ public class RecoverableZooKeeper {
         try {
           long startTime = EnvironmentEdgeManager.currentTime();
           List<OpResult> opResults = checkZk().multi(multiOps);
-          this.metrics.registerWriteOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+          this.metrics.registerWriteOperationLatency(
+                  Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
           return opResults;
         } catch (KeeperException e) {
           this.metrics.registerFailedZKCall();
@@ -741,13 +762,15 @@ public class RecoverableZooKeeper {
     String nodePrefix = path.substring(lastSlashIdx+1);
     long startTime = EnvironmentEdgeManager.currentTime();
     List<String> nodes = checkZk().getChildren(parent, false);
-    this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+    this.metrics.registerReadOperationLatency(
+            Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
     List<String> matching = filterByPrefix(nodes, nodePrefix);
     for (String node : matching) {
       String nodePath = parent + "/" + node;
       startTime = EnvironmentEdgeManager.currentTime();
       Stat stat = checkZk().exists(nodePath, false);
-      this.metrics.registerReadOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+      this.metrics.registerReadOperationLatency(
+              Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
       if (stat != null) {
         return nodePath;
       }
@@ -760,7 +783,9 @@ public class RecoverableZooKeeper {
   }
 
   public synchronized void close() throws InterruptedException {
-    if (zk != null) zk.close();
+    if (zk != null) {
+      zk.close();
+    }
   }
 
   public synchronized States getState() {
@@ -778,7 +803,8 @@ public class RecoverableZooKeeper {
   public void sync(String path, AsyncCallback.VoidCallback cb, Object ctx) throws KeeperException {
     long startTime = EnvironmentEdgeManager.currentTime();
     checkZk().sync(path, cb, null);
-    this.metrics.registerSyncOperationLatency(Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
+    this.metrics.registerSyncOperationLatency(
+            Math.min(EnvironmentEdgeManager.currentTime() - startTime,  1));
   }
 
   /**

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/RegionNormalizerTracker.java

@@ -18,16 +18,17 @@
 
 package org.apache.hadoop.hbase.zookeeper;
 
+import java.io.IOException;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
-import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.RegionNormalizerProtos;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.zookeeper.KeeperException;
 
-import java.io.IOException;
+import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.RegionNormalizerProtos;
 
 /**
  * Tracks region normalizer state up in ZK
@@ -35,8 +36,7 @@ import java.io.IOException;
 public class RegionNormalizerTracker extends ZKNodeTracker {
   private static final Log LOG = LogFactory.getLog(RegionNormalizerTracker.class);
 
-  public RegionNormalizerTracker(ZKWatcher watcher,
+  public RegionNormalizerTracker(ZKWatcher watcher, Abortable abortable) {
-                             Abortable abortable) {
     super(watcher, watcher.znodePaths.regionNormalizerZNode, abortable);
   }
 
@@ -59,7 +59,7 @@ public class RegionNormalizerTracker extends ZKNodeTracker {
   /**
    * Set region normalizer on/off
    * @param normalizerOn whether normalizer should be on or off
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public void setNormalizerOn(boolean normalizerOn) throws KeeperException {
     byte [] upData = toByteArray(normalizerOn);

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKAclReset.java

@@ -26,9 +26,9 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.conf.Configured;
 import org.apache.hadoop.hbase.HBaseConfiguration;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.util.Tool;
 import org.apache.hadoop.util.ToolRunner;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.ZooDefs;
 import org.apache.zookeeper.ZooKeeper;
 

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKClusterId.java

@@ -23,8 +23,8 @@ import java.util.UUID;
 
 import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.ClusterId;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.KeeperException;
 
 /**
@@ -90,7 +90,7 @@ public class ZKClusterId {
    * Get the UUID for the provided ZK watcher. Doesn't handle any ZK exceptions
    * @param zkw watcher connected to an ensemble
    * @return the UUID read from zookeeper
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static UUID getUUIDForCluster(ZKWatcher zkw) throws KeeperException {
     String uuid = readClusterIdZNode(zkw);

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKLeaderManager.java

@@ -23,8 +23,8 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.hbase.Stoppable;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.KeeperException;
 
 /**

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKMainServer.java

@@ -76,22 +76,26 @@ public class ZKMainServer {
   }
 
   /**
-   * @param args
+   * @param args the arguments to check
    * @return True if argument strings have a '-server' in them.
    */
-  private static boolean hasServer(final String args[]) {
+  private static boolean hasServer(final String[] args) {
     return args.length > 0 && args[0].equals(SERVER_ARG);
   }
 
   /**
-   * @param args
+   * @param args the arguments to check for command-line arguments
    * @return True if command-line arguments were passed.
    */
-  private static boolean hasCommandLineArguments(final String args[]) {
+  private static boolean hasCommandLineArguments(final String[] args) {
     if (hasServer(args)) {
-      if (args.length < 2) throw new IllegalStateException("-server param but no value");
+      if (args.length < 2) {
+        throw new IllegalStateException("-server param but no value");
+      }
+
       return args.length > 2;
     }
+
     return args.length > 0;
   }
 
@@ -99,7 +103,7 @@ public class ZKMainServer {
    * Run the tool.
    * @param args Command line arguments. First arg is path to zookeepers file.
    */
-  public static void main(String args[]) throws Exception {
+  public static void main(String[] args) throws Exception {
     String [] newArgs = args;
     if (!hasServer(args)) {
       // Add the zk ensemble from configuration if none passed on command-line.

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKNodeTracker.java

@@ -53,9 +53,10 @@ public abstract class ZKNodeTracker extends ZKListener {
    *
    * <p>After construction, use {@link #start} to kick off tracking.
    *
-   * @param watcher
+   * @param watcher reference to the {@link ZKWatcher} which also contains configuration and
-   * @param node
+   *                constants
-   * @param abortable
+   * @param node path of the node being tracked
+   * @param abortable used to abort if a fatal error occurs
    */
   public ZKNodeTracker(ZKWatcher watcher, String node,
                        Abortable abortable) {
@@ -109,14 +110,17 @@ public abstract class ZKNodeTracker extends ZKListener {
    * Gets the data of the node, blocking until the node is available or the
    * specified timeout has elapsed.
    *
-   * @param timeout maximum time to wait for the node data to be available,
+   * @param timeout maximum time to wait for the node data to be available, n milliseconds. Pass 0
-   * n milliseconds.  Pass 0 for no timeout.
+   *                for no timeout.
    * @return data of the node
    * @throws InterruptedException if the waiting thread is interrupted
    */
   public synchronized byte [] blockUntilAvailable(long timeout, boolean refresh)
-  throws InterruptedException {
+          throws InterruptedException {
-    if (timeout < 0) throw new IllegalArgumentException();
+    if (timeout < 0) {
+      throw new IllegalArgumentException();
+    }
+
     boolean notimeout = timeout == 0;
     long startTime = System.currentTimeMillis();
     long remaining = timeout;
@@ -137,9 +141,8 @@ public abstract class ZKNodeTracker extends ZKListener {
         try {
           nodeExistsChecked = (ZKUtil.checkExists(watcher, node) != -1);
         } catch (KeeperException e) {
-          LOG.warn(
+          LOG.warn("Got exception while trying to check existence in  ZooKeeper" +
-            "Got exception while trying to check existence in  ZooKeeper" +
+            " of the node: " + node + ", retrying if timeout not reached", e);
-            " of the node: "+node+", retrying if timeout not reached",e );
         }
 
         // It did not exists, and now it does.
@@ -188,7 +191,10 @@ public abstract class ZKNodeTracker extends ZKListener {
 
   @Override
   public synchronized void nodeCreated(String path) {
-    if (!path.equals(node)) return;
+    if (!path.equals(node)) {
+      return;
+    }
+
     try {
       byte [] data = ZKUtil.getDataAndWatch(watcher, node);
       if (data != null) {

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKServerTool.java

@@ -19,6 +19,9 @@
 
 package org.apache.hadoop.hbase.zookeeper;
 
+import java.util.LinkedList;
+import java.util.List;
+
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.HBaseInterfaceAudience;
@@ -26,15 +29,15 @@ import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.yetus.audience.InterfaceAudience;
 
-import java.util.LinkedList;
-import java.util.List;
-
 /**
  * Tool for reading ZooKeeper servers from HBase XML configuration and producing
  * a line-by-line list for use by bash scripts.
  */
 @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
-public class ZKServerTool {
+public final class ZKServerTool {
+  private ZKServerTool() {
+  }
+
   public static ServerName[] readZKNodes(Configuration conf) {
     List<ServerName> hosts = new LinkedList<>();
     String quorum = conf.get(HConstants.ZOOKEEPER_QUORUM, HConstants.LOCALHOST);
@@ -56,7 +59,7 @@ public class ZKServerTool {
    * Run the tool.
    * @param args Command line arguments.
    */
-  public static void main(String args[]) {
+  public static void main(String[] args) {
     for(ServerName server: readZKNodes(HBaseConfiguration.create())) {
       // bin/zookeeper.sh relies on the "ZK host" string for grepping which is case sensitive.
       System.out.println("ZK host: " + server.getHostname());

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKSplitLog.java

@@ -30,12 +30,16 @@ import org.apache.hadoop.hbase.HConstants;
 import org.apache.yetus.audience.InterfaceAudience;
 
 /**
- * Common methods and attributes used by SplitLogManager and SplitLogWorker running distributed splitting of WAL logs.
+ * Common methods and attributes used by SplitLogManager and SplitLogWorker running distributed
+ * splitting of WAL logs.
  */
 @InterfaceAudience.Private
-public class ZKSplitLog {
+public final class ZKSplitLog {
   private static final Log LOG = LogFactory.getLog(ZKSplitLog.class);
 
+  private ZKSplitLog() {
+  }
+
   /**
    * Gets the full path node name for the log file being split.
    * This method will url encode the filename.
@@ -80,7 +84,9 @@ public class ZKSplitLog {
   }
 
   /**
-   * @param zkw
+   * Checks if the given path represents a rescan node.
+   *
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and constants
    * @param path the absolute path, starts with '/'
    * @return whether the path represents a rescan node
    */

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java

@@ -45,12 +45,8 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.AuthUtil;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.HConstants;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
 import org.apache.hadoop.hbase.security.Superusers;
-import org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException;
-import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.ReplicationProtos;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.Threads;
 import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.CreateAndFailSilent;
@@ -59,6 +55,7 @@ import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.SetData;
 import org.apache.hadoop.security.SecurityUtil;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.authentication.util.KerberosUtil;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.AsyncCallback;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.KeeperException;
@@ -77,6 +74,10 @@ import org.apache.zookeeper.proto.DeleteRequest;
 import org.apache.zookeeper.proto.SetDataRequest;
 import org.apache.zookeeper.server.ZooKeeperSaslServer;
 
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException;
+import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.ReplicationProtos;
+
 /**
  * Internal HBase utility class for ZooKeeper.
  *
@@ -87,11 +88,14 @@ import org.apache.zookeeper.server.ZooKeeperSaslServer;
  * If ZK is required for the operation, the server will need to be aborted.
  */
 @InterfaceAudience.Private
-public class ZKUtil {
+public final class ZKUtil {
   private static final Log LOG = LogFactory.getLog(ZKUtil.class);
 
   private static int zkDumpConnectionTimeOut;
 
+  private ZKUtil() {
+  }
+
   /**
    * Creates a new connection to ZooKeeper, pulling settings and ensemble config
    * from the specified configuration object using methods from {@link ZKConfig}.
@@ -198,13 +202,15 @@ public class ZKUtil {
       String userNameKey, String hostname,
       String loginContextProperty, String loginContextName)
       throws IOException {
-    if (!isSecureZooKeeper(conf))
+    if (!isSecureZooKeeper(conf)) {
       return;
+    }
 
     // User has specified a jaas.conf, keep this one as the good one.
     // HBASE_OPTS="-Djava.security.auth.login.config=jaas.conf"
-    if (System.getProperty("java.security.auth.login.config") != null)
+    if (System.getProperty("java.security.auth.login.config") != null) {
       return;
+    }
 
     // No keytab specified, no auth
     String keytabFilename = conf.get(keytabFileKey);
@@ -295,7 +301,11 @@ public class ZKUtil {
         KEYTAB_KERBEROS_OPTIONS.put("useTicketCache", useTicketCache ? "true" : "false");
         return KEYTAB_KERBEROS_CONF;
       }
-      if (baseConfig != null) return baseConfig.getAppConfigurationEntry(appName);
+
+      if (baseConfig != null) {
+        return baseConfig.getAppConfigurationEntry(appName);
+      }
+
       return(null);
     }
   }
@@ -454,7 +464,7 @@ public class ZKUtil {
    * @param zkw zookeeper reference
    * @param znode node to get children of and watch
    * @return list of znode names, null if the node doesn't exist
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static List<String> listChildrenAndWatchThem(ZKWatcher zkw,
       String znode) throws KeeperException {
@@ -544,8 +554,8 @@ public class ZKUtil {
     try {
       return !zkw.getRecoverableZooKeeper().getChildren(znode, null).isEmpty();
     } catch(KeeperException.NoNodeException ke) {
-      LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
+      LOG.debug(zkw.prefix("Unable to list children of znode " + znode +
-      "because node does not exist (not an error)"));
+              " because node does not exist (not an error)"));
       return false;
     } catch (KeeperException e) {
       LOG.warn(zkw.prefix("Unable to list children of znode " + znode), e);
@@ -591,8 +601,8 @@ public class ZKUtil {
 
   /**
    * Get znode data. Does not set a watcher.
-   * @return ZNode data, null if the node does not exist or if there is an
+   *
-   *  error.
+   * @return ZNode data, null if the node does not exist or if there is an error.
    */
   public static byte [] getData(ZKWatcher zkw, String znode)
       throws KeeperException, InterruptedException {
@@ -748,17 +758,16 @@ public class ZKUtil {
    * Sets no watches under any conditions.
    *
    * @param zkw zk reference
-   * @param znode
+   * @param znode the path to the ZNode
-   * @param data
+   * @param data the data to store in ZooKeeper
-   * @param expectedVersion
+   * @param expectedVersion the expected version
    * @throws KeeperException if unexpected zookeeper exception
    * @throws KeeperException.BadVersionException if version mismatch
    * @deprecated Unused
    */
   @Deprecated
-  public static void updateExistingNodeData(ZKWatcher zkw, String znode,
+  public static void updateExistingNodeData(ZKWatcher zkw, String znode, byte[] data,
-                                            byte [] data, int expectedVersion)
+      int expectedVersion) throws KeeperException {
-  throws KeeperException {
     try {
       zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion);
     } catch(InterruptedException ie) {
@@ -808,11 +817,10 @@ public class ZKUtil {
    * @param zkw zk reference
    * @param znode path of node
    * @param data data to set for node
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
-  public static void createSetData(final ZKWatcher zkw, final String znode,
+  public static void createSetData(final ZKWatcher zkw, final String znode, final byte [] data)
-                                   final byte [] data)
+          throws KeeperException {
-  throws KeeperException {
     if (checkExists(zkw, znode) == -1) {
       ZKUtil.createWithParents(zkw, znode, data);
     } else {
@@ -1025,9 +1033,8 @@ public class ZKUtil {
    * @return true name of the newly created znode or null
    * @throws KeeperException if unexpected zookeeper exception
    */
-  public static String createNodeIfNotExistsNoWatch(ZKWatcher zkw, String znode,
+  public static String createNodeIfNotExistsNoWatch(ZKWatcher zkw, String znode, byte[] data,
-                                                    byte[] data, CreateMode createMode) throws KeeperException {
+      CreateMode createMode) throws KeeperException {
-
     String createdZNode = null;
     try {
       createdZNode = zkw.getRecoverableZooKeeper().create(znode, data,
@@ -1069,7 +1076,8 @@ public class ZKUtil {
         throw KeeperException.create(KeeperException.Code.SYSTEMERROR,
             "ZK.exists returned null (i.e.: znode does not exist) for znode=" + znode);
       }
-     return stat.getVersion();
+
+      return stat.getVersion();
     } catch (InterruptedException e) {
       zkw.interruptedException(e);
       return -1;
@@ -1086,8 +1094,8 @@ public class ZKUtil {
    * @param zkw zk reference
    * @param znode path of node to create
    * @param data data of node to create
-   * @param cb
+   * @param cb the callback to use for the creation
-   * @param ctx
+   * @param ctx the context to use for the creation
    */
   public static void asyncCreate(ZKWatcher zkw,
       String znode, byte [] data, final AsyncCallback.StringCallback cb,
@@ -1232,9 +1240,10 @@ public class ZKUtil {
 
   /**
    * Deletes the specified node.  Fails silent if the node does not exist.
-   * @param zkw
+   *
-   * @param node
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @throws KeeperException
+   * @param node the node to delete
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static void deleteNodeFailSilent(ZKWatcher zkw, String node)
   throws KeeperException {
@@ -1273,7 +1282,7 @@ public class ZKUtil {
    * Sets no watches.  Throws all exceptions besides dealing with deletion of
    * children.
    *
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static void deleteChildrenRecursively(ZKWatcher zkw, String node)
       throws KeeperException {
@@ -1506,7 +1515,7 @@ public class ZKUtil {
      * ZKUtilOp representing createAndFailSilent in ZooKeeper
      * (attempt to create node, ignore error if already exists)
      */
-    public static class CreateAndFailSilent extends ZKUtilOp {
+    public static final class CreateAndFailSilent extends ZKUtilOp {
       private byte [] data;
 
       private CreateAndFailSilent(String path, byte [] data) {
@@ -1520,8 +1529,12 @@ public class ZKUtil {
 
       @Override
       public boolean equals(Object o) {
-        if (this == o) return true;
+        if (this == o) {
-        if (!(o instanceof CreateAndFailSilent)) return false;
+          return true;
+        }
+        if (!(o instanceof CreateAndFailSilent)) {
+          return false;
+        }
 
         CreateAndFailSilent op = (CreateAndFailSilent) o;
         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
@@ -1538,15 +1551,19 @@ public class ZKUtil {
      * ZKUtilOp representing deleteNodeFailSilent in ZooKeeper
      * (attempt to delete node, ignore error if node doesn't exist)
      */
-    public static class DeleteNodeFailSilent extends ZKUtilOp {
+    public static final class DeleteNodeFailSilent extends ZKUtilOp {
       private DeleteNodeFailSilent(String path) {
         super(path);
       }
 
       @Override
       public boolean equals(Object o) {
-        if (this == o) return true;
+        if (this == o) {
-        if (!(o instanceof DeleteNodeFailSilent)) return false;
+          return true;
+        }
+        if (!(o instanceof DeleteNodeFailSilent)) {
+          return false;
+        }
 
         return super.equals(o);
       }
@@ -1560,7 +1577,7 @@ public class ZKUtil {
     /**
      * ZKUtilOp representing setData in ZooKeeper
      */
-    public static class SetData extends ZKUtilOp {
+    public static final class SetData extends ZKUtilOp {
       private byte [] data;
 
       private SetData(String path, byte [] data) {
@@ -1574,8 +1591,12 @@ public class ZKUtil {
 
       @Override
       public boolean equals(Object o) {
-        if (this == o) return true;
+        if (this == o) {
-        if (!(o instanceof SetData)) return false;
+          return true;
+        }
+        if (!(o instanceof SetData)) {
+          return false;
+        }
 
         SetData op = (SetData) o;
         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
@@ -1592,9 +1613,10 @@ public class ZKUtil {
   /**
    * Convert from ZKUtilOp to ZKOp
    */
-  private static Op toZooKeeperOp(ZKWatcher zkw, ZKUtilOp op)
+  private static Op toZooKeeperOp(ZKWatcher zkw, ZKUtilOp op) throws UnsupportedOperationException {
-  throws UnsupportedOperationException {
+    if(op == null) {
-    if(op == null) return null;
+      return null;
+    }
 
     if (op instanceof CreateAndFailSilent) {
       CreateAndFailSilent cafs = (CreateAndFailSilent)op;
@@ -1629,14 +1651,16 @@ public class ZKUtil {
    * In this case, if the previous conditions hold, the commands are run sequentially, which should
    * result in the correct final state, but means that the operations will not run atomically.
    *
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public static void multiOrSequential(ZKWatcher zkw, List<ZKUtilOp> ops,
                                        boolean runSequentialOnMultiFailure) throws KeeperException {
     if (zkw.getConfiguration().get("hbase.zookeeper.useMulti") != null) {
       LOG.warn("hbase.zookeeper.useMulti is deprecated. Default to true always.");
     }
-    if (ops == null) return;
+    if (ops == null) {
+      return;
+    }
 
     List<Op> zkOps = new LinkedList<>();
     for (ZKUtilOp op : ops) {
@@ -1646,21 +1670,21 @@ public class ZKUtil {
       zkw.getRecoverableZooKeeper().multi(zkOps);
     } catch (KeeperException ke) {
       switch (ke.code()) {
-      case NODEEXISTS:
+        case NODEEXISTS:
-      case NONODE:
+        case NONODE:
-      case BADVERSION:
+        case BADVERSION:
-      case NOAUTH:
+        case NOAUTH:
-        // if we get an exception that could be solved by running sequentially
+          // if we get an exception that could be solved by running sequentially
-        // (and the client asked us to), then break out and run sequentially
+          // (and the client asked us to), then break out and run sequentially
-        if (runSequentialOnMultiFailure) {
+          if (runSequentialOnMultiFailure) {
-          LOG.info("On call to ZK.multi, received exception: " + ke.toString() + "."
+            LOG.info("On call to ZK.multi, received exception: " + ke.toString() + "."
-              + "  Attempting to run operations sequentially because"
+                + "  Attempting to run operations sequentially because"
-              + " runSequentialOnMultiFailure is: " + runSequentialOnMultiFailure + ".");
+                + " runSequentialOnMultiFailure is: " + runSequentialOnMultiFailure + ".");
-          processSequentially(zkw, ops);
+            processSequentially(zkw, ops);
-          break;
+            break;
-        }
+          }
-      default:
+        default:
-        throw ke;
+          throw ke;
       }
     } catch (InterruptedException ie) {
       zkw.interruptedException(ie);
@@ -1748,14 +1772,19 @@ public class ZKUtil {
 
   /**
    * Appends replication znodes to the passed StringBuilder.
-   * @param zkw
+   *
-   * @param sb
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
-   * @throws KeeperException
+   * @param sb the {@link StringBuilder} to append to
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   private static void getReplicationZnodesDump(ZKWatcher zkw, StringBuilder sb)
       throws KeeperException {
     String replicationZnode = zkw.znodePaths.replicationZNode;
-    if (ZKUtil.checkExists(zkw, replicationZnode) == -1) return;
+
+    if (ZKUtil.checkExists(zkw, replicationZnode) == -1) {
+      return;
+    }
+
     // do a ls -r on this znode
     sb.append("\n").append(replicationZnode).append(": ");
     List<String> children = ZKUtil.listChildrenNoWatch(zkw, replicationZnode);
@@ -1790,7 +1819,7 @@ public class ZKUtil {
 
   /**
    * Returns a string with replication znodes and position of the replication log
-   * @param zkw
+   * @param zkw reference to the {@link ZKWatcher} which also contains configuration and operation
    * @return aq string of replication znodes and log positions
    */
   public static String getReplicationZnodesDump(ZKWatcher zkw) throws KeeperException {
@@ -1858,13 +1887,16 @@ public class ZKUtil {
     }
   }
 
-  private static void appendPeerState(ZKWatcher zkw, String znodeToProcess,
+  private static void appendPeerState(ZKWatcher zkw, String znodeToProcess, StringBuilder sb)
-                                      StringBuilder sb) throws KeeperException, InvalidProtocolBufferException {
+          throws KeeperException, InvalidProtocolBufferException {
     String peerState = zkw.getConfiguration().get("zookeeper.znode.replication.peers.state",
       "peer-state");
     int pblen = ProtobufUtil.lengthOfPBMagic();
     for (String child : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
-      if (!child.equals(peerState)) continue;
+      if (!child.equals(peerState)) {
+        continue;
+      }
+
       String peerStateZnode = ZNodePaths.joinZNode(znodeToProcess, child);
       sb.append("\n").append(peerStateZnode).append(": ");
       byte[] peerStateData;
@@ -1929,7 +1961,10 @@ public class ZKUtil {
 
   private static void logRetrievedMsg(final ZKWatcher zkw,
       final String znode, final byte [] data, final boolean watcherSet) {
-    if (!LOG.isTraceEnabled()) return;
+    if (!LOG.isTraceEnabled()) {
+      return;
+    }
+
     LOG.trace(zkw.prefix("Retrieved " + ((data == null)? 0: data.length) +
       " byte(s) of data from znode " + znode +
       (watcherSet? " and set watcher; ": "; data=") +
@@ -2008,7 +2043,10 @@ public class ZKUtil {
    * @param root name of the root directory in zk to print
    */
   public static void logZKTree(ZKWatcher zkw, String root) {
-    if (!LOG.isDebugEnabled()) return;
+    if (!LOG.isDebugEnabled()) {
+      return;
+    }
+
     LOG.debug("Current zk system:");
     String prefix = "|-";
     LOG.debug(prefix + root);
@@ -2027,7 +2065,11 @@ public class ZKUtil {
   protected static void logZKTree(ZKWatcher zkw, String root, String prefix)
       throws KeeperException {
     List<String> children = ZKUtil.listChildrenNoWatch(zkw, root);
-    if (children == null) return;
+
+    if (children == null) {
+      return;
+    }
+
     for (String child : children) {
       LOG.debug(prefix + child);
       String node = ZNodePaths.joinZNode(root.equals("/") ? "" : root, child);
@@ -2036,7 +2078,7 @@ public class ZKUtil {
   }
 
   /**
-   * @param position
+   * @param position the position to serialize
    * @return Serialized protobuf of <code>position</code> with pb magic prefix prepended suitable
    *         for use as content of an wal position in a replication queue.
    */
@@ -2049,7 +2091,7 @@ public class ZKUtil {
   /**
    * @param bytes - Content of a WAL position znode.
    * @return long - The current WAL position.
-   * @throws DeserializationException
+   * @throws DeserializationException if the WAL position cannot be parsed
    */
   public static long parseWALPositionFrom(final byte[] bytes) throws DeserializationException {
     if (bytes == null) {

hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKWatcher.java

@@ -33,9 +33,9 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.AuthUtil;
 import org.apache.hadoop.hbase.ZooKeeperConnectionException;
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.security.Superusers;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.KeeperException;
 import org.apache.zookeeper.WatchedEvent;
 import org.apache.zookeeper.Watcher;
@@ -85,8 +85,6 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
   // negotiation to complete
   public CountDownLatch saslLatch = new CountDownLatch(1);
 
-
-
   private final Configuration conf;
 
   /* A pattern that matches a Kerberos name, borrowed from Hadoop's KerberosName */
@@ -95,8 +93,8 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
   /**
    * Instantiate a ZooKeeper connection and watcher.
    * @param identifier string that is passed to RecoverableZookeeper to be used as
-   * identifier for this instance. Use null for default.
+   *                   identifier for this instance. Use null for default.
-   * @throws IOException
+   * @throws IOException if the connection to ZooKeeper fails
    * @throws ZooKeeperConnectionException
    */
   public ZKWatcher(Configuration conf, String identifier,
@@ -106,13 +104,13 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
 
   /**
    * Instantiate a ZooKeeper connection and watcher.
-   * @param conf
+   * @param conf the configuration to use
    * @param identifier string that is passed to RecoverableZookeeper to be used as identifier for
    *          this instance. Use null for default.
    * @param abortable Can be null if there is on error there is no host to abort: e.g. client
    *          context.
-   * @param canCreateBaseZNode
+   * @param canCreateBaseZNode true if a base ZNode can be created
-   * @throws IOException
+   * @throws IOException if the connection to ZooKeeper fails
    * @throws ZooKeeperConnectionException
    */
   public ZKWatcher(Configuration conf, String identifier,
@@ -211,7 +209,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
   /**
    * Set the znode perms recursively. This will do post-order recursion, so that baseZnode ACLs
    * will be set last in case the master fails in between.
-   * @param znode
+   * @param znode the ZNode to set the permissions for
    */
   private void setZnodeAclsRecursive(String znode) throws KeeperException, InterruptedException {
     List<String> children = recoverableZooKeeper.getChildren(znode, false);
@@ -228,7 +226,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
    * Checks whether the ACLs returned from the base znode (/hbase) is set for secure setup.
    * @param acls acls from zookeeper
    * @return whether ACLs are set for the base znode
-   * @throws IOException
+   * @throws IOException if getting the current user fails
    */
   private boolean isBaseZnodeAclSetup(List<ACL> acls) throws IOException {
     if (LOG.isDebugEnabled()) {
@@ -355,7 +353,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
    * Adds this instance's identifier as a prefix to the passed <code>str</code>
    * @param str String to amend.
    * @return A new string with this instance's identifier as prefix: e.g.
-   * if passed 'hello world', the returned string could be
+   *         if passed 'hello world', the returned string could be
    */
   public String prefix(final String str) {
     return this.toString() + " " + str;
@@ -364,7 +362,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
   /**
    * Get the znodes corresponding to the meta replicas from ZK
    * @return list of znodes
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
   public List<String> getMetaReplicaNodes() throws KeeperException {
     List<String> childrenOfBaseNode = ZKUtil.listChildrenNoWatch(this, znodePaths.baseZNode);
@@ -372,7 +370,9 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
     if (childrenOfBaseNode != null) {
       String pattern = conf.get("zookeeper.znode.metaserver","meta-region-server");
       for (String child : childrenOfBaseNode) {
-        if (child.startsWith(pattern)) metaReplicaNodes.add(child);
+        if (child.startsWith(pattern)) {
+          metaReplicaNodes.add(child);
+        }
       }
     }
     return metaReplicaNodes;
@@ -380,7 +380,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
 
   /**
    * Register the specified listener to receive ZooKeeper events.
-   * @param listener
+   * @param listener the listener to register
    */
   public void registerListener(ZKListener listener) {
     listeners.add(listener);
@@ -389,7 +389,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
   /**
    * Register the specified listener to receive ZooKeeper events and add it as
    * the first in the list of current listeners.
-   * @param listener
+   * @param listener the listener to register
    */
   public void registerListenerFirst(ZKListener listener) {
     listeners.add(0, listener);
@@ -512,7 +512,7 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
    * call, it's possible for the Abortable to catch it and try to create a new
    * session with ZooKeeper. This is what the client does in HCM.
    * <p>
-   * @param event
+   * @param event the connection-related event
    */
   private void connectionEvent(WatchedEvent event) {
     switch(event.getState()) {
@@ -571,11 +571,10 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
    * <p>
    * TODO: Currently this method rethrows the exception to let the caller handle
    * <p>
-   * @param ke
+   * @param ke the exception to rethrow
-   * @throws KeeperException
+   * @throws KeeperException if a ZooKeeper operation fails
    */
-  public void keeperException(KeeperException ke)
+  public void keeperException(KeeperException ke) throws KeeperException {
-  throws KeeperException {
     LOG.error(prefix("Received unexpected KeeperException, re-throwing exception"), ke);
     throw ke;
   }
@@ -623,8 +622,11 @@ public class ZKWatcher implements Watcher, Abortable, Closeable {
 
   @Override
   public void abort(String why, Throwable e) {
-    if (this.abortable != null) this.abortable.abort(why, e);
+    if (this.abortable != null) {
-    else this.aborted = true;
+      this.abortable.abort(why, e);
+    } else {
+      this.aborted = true;
+    }
   }
 
   @Override