HBASE-27203 Clean up error-prone findings in hbase-client [branch-2] (#4651)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Viraj Jasani <vjasani@apache.org>

Author: apurtell

hbase-client/src/main/java/org/apache/hadoop/hbase/AsyncMetaTableAccessor.java

@@ -101,11 +101,7 @@ public static CompletableFuture<Optional<TableState>> getTableState(AsyncTable<?
     return future;
   }
 
-  /**
-   * Returns the HRegionLocation from meta for the given region n * @param regionName region we're
-   * looking for
-   * @return HRegionLocation for the given region
-   */
+  /** Returns the HRegionLocation from meta for the given region */
   public static CompletableFuture<Optional<HRegionLocation>>
     getRegionLocation(AsyncTable<?> metaTable, byte[] regionName) {
     CompletableFuture<Optional<HRegionLocation>> future = new CompletableFuture<>();
@@ -127,11 +123,7 @@ public static CompletableFuture<Optional<TableState>> getTableState(AsyncTable<?
     return future;
   }
 
-  /**
-   * Returns the HRegionLocation from meta for the given encoded region name n * @param
-   * encodedRegionName region we're looking for
-   * @return HRegionLocation for the given region
-   */
+  /** Returns the HRegionLocation from meta for the given encoded region name */
   public static CompletableFuture<Optional<HRegionLocation>>
     getRegionLocationWithEncodedName(AsyncTable<?> metaTable, byte[] encodedRegionName) {
     CompletableFuture<Optional<HRegionLocation>> future = new CompletableFuture<>();
@@ -176,8 +168,9 @@ private static Optional<TableState> getTableState(Result r) throws IOException {
   }
 
   /**
-   * Used to get all region locations for the specific table. n * @param tableName table we're
-   * looking for, can be null for getting all regions
+   * Used to get all region locations for the specific table
+   * @param metaTable scanner over meta table
+   * @param tableName table we're looking for, can be null for getting all regions
    * @return the list of region locations. The return value will be wrapped by a
    *         {@link CompletableFuture}.
    */
@@ -200,8 +193,9 @@ public static CompletableFuture<List<HRegionLocation>> getTableHRegionLocations(
   }
 
   /**
-   * Used to get table regions' info and server. n * @param tableName table we're looking for, can
-   * be null for getting all regions
+   * Used to get table regions' info and server.
+   * @param metaTable                   scanner over meta table
+   * @param tableName                   table we're looking for, can be null for getting all regions
    * @param excludeOfflinedSplitParents don't return split parents
    * @return the list of regioninfos and server. The return value will be wrapped by a
    *         {@link CompletableFuture}.
@@ -259,9 +253,11 @@ void add(Result r) {
   }
 
   /**
-   * Performs a scan of META table for given table. n * @param tableName table withing we scan
-   * @param type    scanned part of meta
-   * @param visitor Visitor invoked against each row
+   * Performs a scan of META table for given table.
+   * @param metaTable scanner over meta table
+   * @param tableName table within we scan
+   * @param type      scanned part of meta
+   * @param visitor   Visitor invoked against each row
    */
   private static CompletableFuture<Void> scanMeta(AsyncTable<AdvancedScanResultConsumer> metaTable,
     TableName tableName, QueryType type, final Visitor visitor) {
@@ -270,11 +266,13 @@ private static CompletableFuture<Void> scanMeta(AsyncTable<AdvancedScanResultCon
   }
 
   /**
-   * Performs a scan of META table for given table. n * @param startRow Where to start the scan
-   * @param stopRow Where to stop the scan
-   * @param type    scanned part of meta
-   * @param maxRows maximum rows to return
-   * @param visitor Visitor invoked against each row
+   * Performs a scan of META table for given table.
+   * @param metaTable scanner over meta table
+   * @param startRow  Where to start the scan
+   * @param stopRow   Where to stop the scan
+   * @param type      scanned part of meta
+   * @param maxRows   maximum rows to return
+   * @param visitor   Visitor invoked against each row
    */
   private static CompletableFuture<Void> scanMeta(AsyncTable<AdvancedScanResultConsumer> metaTable,
     byte[] startRow, byte[] stopRow, QueryType type, int maxRows, final Visitor visitor) {
@@ -410,25 +408,32 @@ private static Scan getMetaScan(AsyncTable<?> metaTable, int rowUpperLimit) {
    *         can't deserialize the result.
    */
   private static Optional<RegionLocations> getRegionLocations(final Result r) {
-    if (r == null) return Optional.empty();
+    if (r == null) {
+      return Optional.empty();
+    }
     Optional<RegionInfo> regionInfo = getHRegionInfo(r, getRegionInfoColumn());
-    if (!regionInfo.isPresent()) return Optional.empty();
+    if (!regionInfo.isPresent()) {
+      return Optional.empty();
+    }
 
     List<HRegionLocation> locations = new ArrayList<HRegionLocation>(1);
     NavigableMap<byte[], NavigableMap<byte[], byte[]>> familyMap = r.getNoVersionMap();
 
     locations.add(getRegionLocation(r, regionInfo.get(), 0));
 
     NavigableMap<byte[], byte[]> infoMap = familyMap.get(getCatalogFamily());
-    if (infoMap == null) return Optional.of(new RegionLocations(locations));
+    if (infoMap == null) {
+      return Optional.of(new RegionLocations(locations));
+    }
 
     // iterate until all serverName columns are seen
     int replicaId = 0;
     byte[] serverColumn = getServerColumn(replicaId);
-    SortedMap<byte[], byte[]> serverMap = null;
-    serverMap = infoMap.tailMap(serverColumn, false);
+    SortedMap<byte[], byte[]> serverMap = infoMap.tailMap(serverColumn, false);
 
-    if (serverMap.isEmpty()) return Optional.of(new RegionLocations(locations));
+    if (serverMap.isEmpty()) {
+      return Optional.of(new RegionLocations(locations));
+    }
 
     for (Map.Entry<byte[], byte[]> entry : serverMap.entrySet()) {
       replicaId = parseReplicaIdFromServerColumn(entry.getKey());

hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterId.java

@@ -51,6 +51,7 @@ public byte[] toByteArray() {
   }
 
   /**
+   * Parse the serialized representation of the {@link ClusterId}
    * @param bytes A pb serialized {@link ClusterId} instance with pb magic prefix
    * @return An instance of {@link ClusterId} made from <code>bytes</code> n * @see #toByteArray()
    */

hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterMetricsBuilder.java

@@ -67,11 +67,11 @@ public static ClusterStatusProtos.ClusterStatus toClusterStatus(ClusterMetrics m
           .collect(Collectors.toList()))
         .addAllTableRegionStatesCount(metrics.getTableRegionStatesCount().entrySet().stream()
           .map(status -> ClusterStatusProtos.TableRegionStatesCount.newBuilder()
-            .setTableName(ProtobufUtil.toProtoTableName((status.getKey())))
+            .setTableName(ProtobufUtil.toProtoTableName(status.getKey()))
             .setRegionStatesCount(ProtobufUtil.toTableRegionStatesCount(status.getValue())).build())
           .collect(Collectors.toList()));
     if (metrics.getMasterName() != null) {
-      builder.setMaster(ProtobufUtil.toServerName((metrics.getMasterName())));
+      builder.setMaster(ProtobufUtil.toServerName(metrics.getMasterName()));
     }
     if (metrics.getMasterTasks() != null) {
       builder.addAllMasterTasks(metrics.getMasterTasks().stream()

hbase-client/src/main/java/org/apache/hadoop/hbase/ClusterStatus.java

@@ -186,6 +186,7 @@ public List<RegionState> getRegionStatesInTransition() {
   }
 
   /** Returns the HBase version string as reported by the HMaster */
+  @Override
   public String getHBaseVersion() {
     return metrics.getHBaseVersion();
   }
@@ -279,6 +280,7 @@ public ServerLoad getLoad(final ServerName sn) {
     return serverMetrics == null ? null : new ServerLoad(serverMetrics);
   }
 
+  @Override
   public String getClusterId() {
     return metrics.getClusterId();
   }
@@ -289,6 +291,7 @@ public List<String> getMasterCoprocessorNames() {
   }
 
   /**
+   * Get the list of master coprocessor names.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getMasterCoprocessorNames} instead.
    */
@@ -299,6 +302,7 @@ public String[] getMasterCoprocessors() {
   }
 
   /**
+   * Get the last major compaction time for a given table.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getLastMajorCompactionTimestamp(TableName)} instead.
    */
@@ -308,6 +312,7 @@ public long getLastMajorCompactionTsForTable(TableName table) {
   }
 
   /**
+   * Get the last major compaction time for a given region.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 Use
    *             {@link #getLastMajorCompactionTimestamp(byte[])} instead.
    */
@@ -317,6 +322,7 @@ public long getLastMajorCompactionTsForRegion(final byte[] region) {
   }
 
   /**
+   * Returns true if the balancer is enabled.
    * @deprecated As of release 2.0.0, this will be removed in HBase 3.0.0 No flag in 2.0
    */
   @Deprecated

hbase-client/src/main/java/org/apache/hadoop/hbase/CoprocessorEnvironment.java

@@ -44,8 +44,8 @@ public interface CoprocessorEnvironment<C extends Coprocessor> {
   int getLoadSequence();
 
   /**
-   * @return a Read-only Configuration; throws {@link UnsupportedOperationException} if you try to
-   *         set a configuration.
+   * Returns a Read-only Configuration; throws {@link UnsupportedOperationException} if you try to
+   * set a configuration.
    */
   Configuration getConfiguration();
 

hbase-client/src/main/java/org/apache/hadoop/hbase/HBaseServerException.java

@@ -44,10 +44,7 @@ public HBaseServerException(boolean serverOverloaded, String message) {
     this.serverOverloaded = serverOverloaded;
   }
 
-  /**
-   * @param t throwable to check for server overloaded state
-   * @return True if the server was considered overloaded when the exception was thrown
-   */
+  /** Returns True if the server was considered overloaded when the exception was thrown */
   public static boolean isServerOverloaded(Throwable t) {
     if (t instanceof HBaseServerException) {
       return ((HBaseServerException) t).isServerOverloaded();