HDDS-748. Use strongly typed metadata Table implementation. Contributed by Elek Marton.

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/ByteArrayKeyValue.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.apache.hadoop.utils.db;
+
+import org.apache.hadoop.utils.db.Table.KeyValue;
+
+/**
+ * Key value for raw Table implementations.
+ */
+public final class ByteArrayKeyValue implements KeyValue<byte[], byte[]> {
+  private byte[] key;
+  private byte[] value;
+
+  private ByteArrayKeyValue(byte[] key, byte[] value) {
+    this.key = key;
+    this.value = value;
+  }
+
+  /**
+   * Create a KeyValue pair.
+   *
+   * @param key   - Key Bytes
+   * @param value - Value bytes
+   * @return KeyValue object.
+   */
+  public static ByteArrayKeyValue create(byte[] key, byte[] value) {
+    return new ByteArrayKeyValue(key, value);
+  }
+
+  /**
+   * Return key.
+   *
+   * @return byte[]
+   */
+  public byte[] getKey() {
+    byte[] result = new byte[key.length];
+    System.arraycopy(key, 0, result, 0, key.length);
+    return result;
+  }
+
+  /**
+   * Return value.
+   *
+   * @return byte[]
+   */
+  public byte[] getValue() {
+    byte[] result = new byte[value.length];
+    System.arraycopy(value, 0, result, 0, value.length);
+    return result;
+  }
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/Codec.java

@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.apache.hadoop.utils.db;
+
+/**
+ * Codec interface to marshall/unmarshall data to/from a byte[] based
+ * key/value store.
+ *
+ * @param <T> Unserialized type
+ */
+public interface Codec<T> {
+
+  /**
+   * Convert object to raw persisted format.
+   */
+  byte[] toPersistedFormat(T object);
+
+  /**
+   * Convert object from raw persisted format.
+   */
+  T fromPersistedFormat(byte[] rawData);
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/CodecRegistry.java

@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.apache.hadoop.utils.db;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Collection of available codecs.
+ */
+public class CodecRegistry {
+
+  private Map<Class, Codec<?>> valueCodecs;
+
+  public CodecRegistry() {
+    valueCodecs = new HashMap<>();
+    valueCodecs.put(String.class, new StringCodec());
+  }
+
+  /**
+   * Convert raw value to strongly typed value/key with the help of a codec.
+   *
+   * @param rawData original byte array from the db.
+   * @param format  Class of the return value
+   * @param <T>     Type of the return value.
+   * @return the object with the parsed field data
+   */
+  public <T> T asObject(byte[] rawData, Class<T> format) {
+    if (valueCodecs.containsKey(format)) {
+      return (T) valueCodecs.get(format).fromPersistedFormat(rawData);
+    } else {
+      throw new IllegalStateException(
+          "Codec is not registered for type: " + format);
+    }
+  }
+
+  /**
+   * Convert strongly typed object to raw data to store it in the kv store.
+   *
+   * @param object typed object.
+   * @param <T>    Type of the typed object.
+   * @return byte array to store it ini the kv store.
+   */
+  public <T> byte[] asRawData(T object) {
+    Class<T> format = (Class<T>) object.getClass();
+    if (valueCodecs.containsKey(format)) {
+      Codec<T> codec = (Codec<T>) valueCodecs.get(format);
+      return codec.toPersistedFormat(object);
+    } else {
+      throw new IllegalStateException(
+          "Codec is not registered for type: " + format);
+    }
+  }
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/DBStore.java

@@ -41,7 +41,17 @@ public interface DBStore extends AutoCloseable {
    * @return - TableStore.
    * @throws IOException on Failure
    */
-  Table getTable(String name) throws IOException;
+  Table<byte[], byte[]> getTable(String name) throws IOException;
+
+  /**
+   * Gets an existing TableStore with implicit key/value conversion.
+   *
+   * @param name - Name of the TableStore to get
+   * @return - TableStore.
+   * @throws IOException on Failure
+   */
+  <KEY, VALUE> Table<KEY, VALUE> getTable(String name,
+      Class<KEY> keyType, Class<VALUE> valueType) throws IOException;
 
   /**
    * Lists the Known list of Tables in a DB.

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBStore.java

@@ -55,6 +55,7 @@ public class RDBStore implements DBStore {
   private final File dbLocation;
   private final WriteOptions writeOptions;
   private final DBOptions dbOptions;
+  private final CodecRegistry codecRegistry;
   private final Hashtable<String, ColumnFamilyHandle> handleTable;
   private ObjectName statMBeanName;
 
@@ -64,7 +65,7 @@ public RDBStore(File dbFile, DBOptions options, Set<TableConfig> families)
     Preconditions.checkNotNull(families);
     Preconditions.checkArgument(families.size() > 0);
     handleTable = new Hashtable<>();
-
+    codecRegistry = new CodecRegistry();
     final List<ColumnFamilyDescriptor> columnFamilyDescriptors =
         new ArrayList<>();
     final List<ColumnFamilyHandle> columnFamilyHandles = new ArrayList<>();
@@ -254,7 +255,7 @@ protected ObjectName getStatMBeanName() {
   }
 
   @Override
-  public Table getTable(String name) throws IOException {
+  public Table<byte[], byte[]> getTable(String name) throws IOException {
     ColumnFamilyHandle handle = handleTable.get(name);
     if (handle == null) {
       throw new IOException("No such table in this DB. TableName : " + name);
@@ -262,6 +263,13 @@ public Table getTable(String name) throws IOException {
     return new RDBTable(this.db, handle, this.writeOptions);
   }
 
+  @Override
+  public <KEY, VALUE> Table<KEY, VALUE> getTable(String name,
+      Class<KEY> keyType, Class<VALUE> valueType) throws IOException {
+    return new TypedTable<KEY, VALUE>(getTable(name), codecRegistry, keyType,
+        valueType);
+  }
+
   @Override
   public ArrayList<Table> listTables() throws IOException {
     ArrayList<Table> returnList = new ArrayList<>();

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBStoreIterator.java

@@ -19,17 +19,17 @@
 
 package org.apache.hadoop.utils.db;
 
-import org.apache.hadoop.utils.db.Table.KeyValue;
-import org.rocksdb.RocksIterator;
-
 import java.io.IOException;
 import java.util.NoSuchElementException;
 import java.util.function.Consumer;
 
+import org.rocksdb.RocksIterator;
+
 /**
  * RocksDB store iterator.
  */
-public class RDBStoreIterator implements TableIterator<KeyValue> {
+public class RDBStoreIterator
+    implements TableIterator<byte[], ByteArrayKeyValue> {
 
   private RocksIterator rocksDBIterator;
 
@@ -39,7 +39,8 @@ public RDBStoreIterator(RocksIterator iterator) {
   }
 
   @Override
-  public void forEachRemaining(Consumer<? super KeyValue> action) {
+  public void forEachRemaining(
+      Consumer<? super ByteArrayKeyValue> action) {
     while(hasNext()) {
       action.accept(next());
     }
@@ -51,9 +52,10 @@ public boolean hasNext() {
   }
 
   @Override
-  public Table.KeyValue next() {
+  public ByteArrayKeyValue next() {
     if (rocksDBIterator.isValid()) {
-      KeyValue value = KeyValue.create(rocksDBIterator.key(), rocksDBIterator
+      ByteArrayKeyValue value =
+          ByteArrayKeyValue.create(rocksDBIterator.key(), rocksDBIterator
           .value());
       rocksDBIterator.next();
       return value;
@@ -72,10 +74,10 @@ public void seekToLast() {
   }
 
   @Override
-  public KeyValue seek(byte[] key) {
+  public ByteArrayKeyValue seek(byte[] key) {
     rocksDBIterator.seek(key);
     if (rocksDBIterator.isValid()) {
-      return KeyValue.create(rocksDBIterator.key(),
+      return ByteArrayKeyValue.create(rocksDBIterator.key(),
           rocksDBIterator.value());
     }
     return null;

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBTable.java

@@ -35,7 +35,8 @@
 /**
  * RocksDB implementation of ozone metadata store.
  */
-public class RDBTable implements Table {
+public class RDBTable implements Table<byte[], byte[]> {
+
 
   private static final Logger LOG =
       LoggerFactory.getLogger(RDBTable.class);
@@ -108,7 +109,7 @@ public void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
 
   @Override
   public boolean isEmpty() throws IOException {
-    try (TableIterator<KeyValue> keyIter = iterator()) {
+    try (TableIterator<byte[], ByteArrayKeyValue> keyIter = iterator()) {
       keyIter.seekToFirst();
       return !keyIter.hasNext();
     }
@@ -145,7 +146,7 @@ public void deleteWithBatch(BatchOperation batch, byte[] key)
   }
 
   @Override
-  public TableIterator<KeyValue> iterator() {
+  public TableIterator<byte[], ByteArrayKeyValue> iterator() {
     ReadOptions readOptions = new ReadOptions();
     return new RDBStoreIterator(db.newIterator(handle, readOptions));
   }

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/StringCodec.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.apache.hadoop.utils.db;
+
+import org.apache.hadoop.hdfs.DFSUtil;
+
+/**
+ * Codec to convert String to/from byte array.
+ */
+public class StringCodec implements Codec<String> {
+
+  @Override
+  public byte[] toPersistedFormat(String object) {
+    if (object != null) {
+      return DFSUtil.string2Bytes(object);
+    } else {
+      return null;
+    }
+  }
+
+  @Override
+  public String fromPersistedFormat(byte[] rawData) {
+    if (rawData != null) {
+      return DFSUtil.bytes2String(rawData);
+    } else {
+      return null;
+    }
+  }
+}

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/Table.java

@@ -30,7 +30,7 @@
  * different kind of tables.
  */
 @InterfaceStability.Evolving
-public interface Table extends AutoCloseable {
+public interface Table<KEY, VALUE> extends AutoCloseable {
 
   /**
    * Puts a key-value pair into the store.
@@ -38,7 +38,7 @@ public interface Table extends AutoCloseable {
    * @param key metadata key
    * @param value metadata value
    */
-  void put(byte[] key, byte[] value) throws IOException;
+  void put(KEY key, VALUE value) throws IOException;
 
   /**
    * Puts a key-value pair into the store as part of a bath operation.
@@ -47,7 +47,7 @@ public interface Table extends AutoCloseable {
    * @param key metadata key
    * @param value metadata value
    */
-  void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
+  void putWithBatch(BatchOperation batch, KEY key, VALUE value)
       throws IOException;
 
   /**
@@ -64,7 +64,7 @@ void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
    * @return value in byte array or null if the key is not found.
    * @throws IOException on Failure
    */
-  byte[] get(byte[] key) throws IOException;
+  VALUE get(KEY key) throws IOException;
 
   /**
    * Deletes a key from the metadata store.
@@ -72,7 +72,7 @@ void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
    * @param key metadata key
    * @throws IOException on Failure
    */
-  void delete(byte[] key) throws IOException;
+  void delete(KEY key) throws IOException;
 
   /**
    * Deletes a key from the metadata store as part of a batch operation.
@@ -81,14 +81,14 @@ void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
    * @param key metadata key
    * @throws IOException on Failure
    */
-  void deleteWithBatch(BatchOperation batch, byte[] key) throws IOException;
+  void deleteWithBatch(BatchOperation batch, KEY key) throws IOException;
 
   /**
    * Returns the iterator for this metadata store.
    *
    * @return MetaStoreIterator
    */
-  TableIterator<KeyValue> iterator();
+  TableIterator<KEY, ? extends KeyValue<KEY, VALUE>> iterator();
 
   /**
    * Returns the Name of this Table.
@@ -100,53 +100,10 @@ void putWithBatch(BatchOperation batch, byte[] key, byte[] value)
   /**
    * Class used to represent the key and value pair of a db entry.
    */
-  class KeyValue {
+  interface KeyValue<KEY, VALUE> {
 
-    private final byte[] key;
+    KEY getKey();
-    private final byte[] value;
 
-    /**
+    VALUE getValue();
-     * KeyValue Constructor, used to represent a key and value of a db entry.
-     *
-     * @param key - Key Bytes
-     * @param value - Value bytes
-     */
-    private KeyValue(byte[] key, byte[] value) {
-      this.key = key;
-      this.value = value;
-    }
-
-    /**
-     * Create a KeyValue pair.
-     *
-     * @param key - Key Bytes
-     * @param value - Value bytes
-     * @return KeyValue object.
-     */
-    public static KeyValue create(byte[] key, byte[] value) {
-      return new KeyValue(key, value);
-    }
-
-    /**
-     * Return key.
-     *
-     * @return byte[]
-     */
-    public byte[] getKey() {
-      byte[] result = new byte[key.length];
-      System.arraycopy(key, 0, result, 0, key.length);
-      return result;
-    }
-
-    /**
-     * Return value.
-     *
-     * @return byte[]
-     */
-    public byte[] getValue() {
-      byte[] result = new byte[value.length];
-      System.arraycopy(value, 0, result, 0, value.length);
-      return result;
-    }
   }
 }

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/TableIterator.java

@@ -27,7 +27,7 @@
  *
  * @param <T>
  */
-public interface TableIterator<T> extends Iterator<T>, Closeable {
+public interface TableIterator<KEY, T> extends Iterator<T>, Closeable {
 
   /**
    * seek to first entry.
@@ -43,8 +43,8 @@ public interface TableIterator<T> extends Iterator<T>, Closeable {
    * Seek to the specific key.
    *
    * @param key - Bytes that represent the key.
-   * @return T.
+   * @return VALUE.
    */
-  T seek(byte[] key);
+  T seek(KEY key);
 
 }

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/TypedTable.java

@@ -0,0 +1,184 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.apache.hadoop.utils.db;
+
+import java.io.IOException;
+
+/**
+ * Strongly typed table implementation.
+ * <p>
+ * Automatically converts values and keys using a raw byte[] based table
+ * implementation and registered converters.
+ *
+ * @param <KEY>   type of the keys in the store.
+ * @param <VALUE> type of the values in the store.
+ */
+public class TypedTable<KEY, VALUE> implements Table<KEY, VALUE> {
+
+  private Table<byte[], byte[]> rawTable;
+
+  private CodecRegistry codecRegistry;
+
+  private Class<KEY> keyType;
+
+  private Class<VALUE> valueType;
+
+  public TypedTable(
+      Table<byte[], byte[]> rawTable,
+      CodecRegistry codecRegistry, Class<KEY> keyType,
+      Class<VALUE> valueType) {
+    this.rawTable = rawTable;
+    this.codecRegistry = codecRegistry;
+    this.keyType = keyType;
+    this.valueType = valueType;
+  }
+
+  @Override
+  public void put(KEY key, VALUE value) throws IOException {
+    byte[] keyData = codecRegistry.asRawData(key);
+    byte[] valueData = codecRegistry.asRawData(value);
+    rawTable.put(keyData, valueData);
+  }
+
+  @Override
+  public void putWithBatch(BatchOperation batch, KEY key, VALUE value)
+      throws IOException {
+    byte[] keyData = codecRegistry.asRawData(key);
+    byte[] valueData = codecRegistry.asRawData(value);
+    rawTable.putWithBatch(batch, keyData, valueData);
+  }
+
+  @Override
+  public boolean isEmpty() throws IOException {
+    return rawTable.isEmpty();
+  }
+
+  @Override
+  public VALUE get(KEY key) throws IOException {
+    byte[] keyBytes = codecRegistry.asRawData(key);
+    byte[] valueBytes = rawTable.get(keyBytes);
+    return codecRegistry.asObject(valueBytes, valueType);
+  }
+
+  @Override
+  public void delete(KEY key) throws IOException {
+    rawTable.delete(codecRegistry.asRawData(key));
+  }
+
+  @Override
+  public void deleteWithBatch(BatchOperation batch, KEY key)
+      throws IOException {
+    rawTable.deleteWithBatch(batch, codecRegistry.asRawData(key));
+
+  }
+
+  @Override
+  public TableIterator<KEY, TypedKeyValue> iterator() {
+    TableIterator<byte[], ? extends KeyValue<byte[], byte[]>> iterator =
+        rawTable.iterator();
+    return new TypedTableIterator(iterator, keyType, valueType);
+  }
+
+  @Override
+  public String getName() throws IOException {
+    return rawTable.getName();
+  }
+
+  @Override
+  public void close() throws Exception {
+    rawTable.close();
+
+  }
+
+  /**
+   * Key value implementation for strongly typed tables.
+   */
+  public class TypedKeyValue implements KeyValue<KEY, VALUE> {
+
+    private KeyValue<byte[], byte[]> rawKeyValue;
+
+    public TypedKeyValue(KeyValue<byte[], byte[]> rawKeyValue) {
+      this.rawKeyValue = rawKeyValue;
+    }
+
+    public TypedKeyValue(KeyValue<byte[], byte[]> rawKeyValue,
+        Class<KEY> keyType, Class<VALUE> valueType) {
+      this.rawKeyValue = rawKeyValue;
+    }
+
+    @Override
+    public KEY getKey() {
+      return codecRegistry.asObject(rawKeyValue.getKey(), keyType);
+    }
+
+    @Override
+    public VALUE getValue() {
+      return codecRegistry.asObject(rawKeyValue.getValue(), valueType);
+    }
+  }
+
+  /**
+   * Table Iterator implementation for strongly typed tables.
+   */
+  public class TypedTableIterator implements TableIterator<KEY, TypedKeyValue> {
+
+    private TableIterator<byte[], ? extends KeyValue<byte[], byte[]>>
+        rawIterator;
+
+    public TypedTableIterator(
+        TableIterator<byte[], ? extends KeyValue<byte[], byte[]>> rawIterator,
+        Class<KEY> keyType,
+        Class<VALUE> valueType) {
+      this.rawIterator = rawIterator;
+    }
+
+    @Override
+    public void seekToFirst() {
+      rawIterator.seekToFirst();
+    }
+
+    @Override
+    public void seekToLast() {
+      rawIterator.seekToLast();
+    }
+
+    @Override
+    public TypedKeyValue seek(KEY key) {
+      byte[] keyBytes = codecRegistry.asRawData(key);
+      KeyValue<byte[], byte[]> result = rawIterator.seek(keyBytes);
+      return new TypedKeyValue(result);
+    }
+
+    @Override
+    public void close() throws IOException {
+      rawIterator.close();
+    }
+
+    @Override
+    public boolean hasNext() {
+      return rawIterator.hasNext();
+    }
+
+    @Override
+    public TypedKeyValue next() {
+      return new TypedKeyValue(rawIterator.next(), keyType,
+          valueType);
+    }
+  }
+}

hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/TestDBStoreBuilder.java

@@ -124,7 +124,7 @@ public void builderWithDataWrites() throws Exception {
         .addTable("First")
         .addTable("Second")
         .build()) {
-      try (Table firstTable = dbStore.getTable("First")) {
+      try (Table<byte[], byte[]> firstTable = dbStore.getTable("First")) {
         byte[] key =
             RandomStringUtils.random(9).getBytes(StandardCharsets.UTF_8);
         byte[] value =
@@ -154,7 +154,7 @@ public void builderWithDiskProfileWrites() throws Exception {
         .addTable("Second")
         .setProfile(DBProfile.DISK)
         .build()) {
-      try (Table firstTable = dbStore.getTable("First")) {
+      try (Table<byte[], byte[]> firstTable = dbStore.getTable("First")) {
         byte[] key =
             RandomStringUtils.random(9).getBytes(StandardCharsets.UTF_8);
         byte[] value =

hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/TestRDBStore.java

@@ -19,8 +19,20 @@
 
 package org.apache.hadoop.utils.db;
 
-import org.apache.commons.lang3.RandomStringUtils;
+import javax.management.MBeanServer;
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
 import org.apache.hadoop.hdfs.DFSUtil;
+
+import org.apache.commons.lang3.RandomStringUtils;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Before;
@@ -34,17 +46,6 @@
 import org.rocksdb.Statistics;
 import org.rocksdb.StatsLevel;
 
-import javax.management.MBeanServer;
-import java.io.IOException;
-import java.lang.management.ManagementFactory;
-import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-
 /**
  * RDBStore Tests.
  */
@@ -126,7 +127,8 @@ public void moveKey() throws Exception {
 
     try (Table firstTable = rdbStore.getTable(families.get(1))) {
       firstTable.put(key, value);
-      try (Table secondTable = rdbStore.getTable(families.get(2))) {
+      try (Table<byte[], byte[]> secondTable = rdbStore
+          .getTable(families.get(2))) {
         rdbStore.move(key, firstTable, secondTable);
         byte[] newvalue = secondTable.get(key);
         // Make sure we have value in the second table
@@ -150,7 +152,8 @@ public void moveWithValue() throws Exception {
         RandomStringUtils.random(10).getBytes(StandardCharsets.UTF_8);
     try (Table firstTable = rdbStore.getTable(families.get(1))) {
       firstTable.put(key, value);
-      try (Table secondTable = rdbStore.getTable(families.get(2))) {
+      try (Table<byte[], byte[]> secondTable = rdbStore
+          .getTable(families.get(2))) {
         rdbStore.move(key, nextValue, firstTable, secondTable);
         byte[] newvalue = secondTable.get(key);
         // Make sure we have value in the second table

hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/TestRDBTableStore.java

@@ -95,7 +95,7 @@ public void getHandle() throws Exception {
 
   @Test
   public void putGetAndEmpty() throws Exception {
-    try (Table testTable = rdbStore.getTable("First")) {
+    try (Table<byte[], byte[]> testTable = rdbStore.getTable("First")) {
       byte[] key =
           RandomStringUtils.random(10).getBytes(StandardCharsets.UTF_8);
       byte[] value =
@@ -209,7 +209,7 @@ public void forEachAndIterator() throws Exception {
         testTable.put(key, value);
       }
       int localCount = 0;
-      try (TableIterator<Table.KeyValue> iter = testTable.iterator()) {
+      try (TableIterator<byte[], Table.KeyValue> iter = testTable.iterator()) {
         while (iter.hasNext()) {
           Table.KeyValue keyValue = iter.next();
           localCount++;

hadoop-hdds/common/src/test/java/org/apache/hadoop/utils/db/TestTypedRDBTableStore.java

@@ -0,0 +1,235 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.apache.hadoop.utils.db;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.utils.db.Table.KeyValue;
+
+import org.apache.commons.lang3.RandomStringUtils;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.rocksdb.ColumnFamilyOptions;
+import org.rocksdb.DBOptions;
+import org.rocksdb.RocksDB;
+import org.rocksdb.Statistics;
+import org.rocksdb.StatsLevel;
+
+/**
+ * Tests for RocksDBTable Store.
+ */
+public class TestTypedRDBTableStore {
+  private static int count = 0;
+  private final List<String> families =
+      Arrays.asList(DFSUtil.bytes2String(RocksDB.DEFAULT_COLUMN_FAMILY),
+          "First", "Second", "Third",
+          "Fourth", "Fifth",
+          "Sixth");
+  @Rule
+  public TemporaryFolder folder = new TemporaryFolder();
+  private RDBStore rdbStore = null;
+  private DBOptions options = null;
+  private CodecRegistry codecRegistry;
+
+  @Before
+  public void setUp() throws Exception {
+    options = new DBOptions();
+    options.setCreateIfMissing(true);
+    options.setCreateMissingColumnFamilies(true);
+
+    Statistics statistics = new Statistics();
+    statistics.setStatsLevel(StatsLevel.ALL);
+    options = options.setStatistics(statistics);
+
+    Set<TableConfig> configSet = new HashSet<>();
+    for (String name : families) {
+      TableConfig newConfig = new TableConfig(name, new ColumnFamilyOptions());
+      configSet.add(newConfig);
+    }
+    rdbStore = new RDBStore(folder.newFolder(), options, configSet);
+
+    codecRegistry = new CodecRegistry();
+
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    if (rdbStore != null) {
+      rdbStore.close();
+    }
+  }
+
+  @Test
+  public void toIOException() {
+  }
+
+  @Test
+  public void putGetAndEmpty() throws Exception {
+    try (Table<String, String> testTable = createTypedTable(
+        "First")) {
+      String key =
+          RandomStringUtils.random(10);
+      String value = RandomStringUtils.random(10);
+      testTable.put(key, value);
+      Assert.assertFalse(testTable.isEmpty());
+      String readValue = testTable.get(key);
+      Assert.assertEquals(value, readValue);
+    }
+    try (Table secondTable = rdbStore.getTable("Second")) {
+      Assert.assertTrue(secondTable.isEmpty());
+    }
+  }
+
+  private Table<String, String> createTypedTable(String name)
+      throws IOException {
+    return new TypedTable<String, String>(
+        rdbStore.getTable(name),
+        codecRegistry,
+        String.class, String.class);
+  }
+
+  @Test
+  public void delete() throws Exception {
+    List<String> deletedKeys = new LinkedList<>();
+    List<String> validKeys = new LinkedList<>();
+    String value =
+        RandomStringUtils.random(10);
+    for (int x = 0; x < 100; x++) {
+      deletedKeys.add(
+          RandomStringUtils.random(10));
+    }
+
+    for (int x = 0; x < 100; x++) {
+      validKeys.add(
+          RandomStringUtils.random(10));
+    }
+
+    // Write all the keys and delete the keys scheduled for delete.
+    //Assert we find only expected keys in the Table.
+    try (Table<String, String> testTable = createTypedTable(
+        "Fourth")) {
+      for (int x = 0; x < deletedKeys.size(); x++) {
+        testTable.put(deletedKeys.get(x), value);
+        testTable.delete(deletedKeys.get(x));
+      }
+
+      for (int x = 0; x < validKeys.size(); x++) {
+        testTable.put(validKeys.get(x), value);
+      }
+
+      for (int x = 0; x < validKeys.size(); x++) {
+        Assert.assertNotNull(testTable.get(validKeys.get(0)));
+      }
+
+      for (int x = 0; x < deletedKeys.size(); x++) {
+        Assert.assertNull(testTable.get(deletedKeys.get(0)));
+      }
+    }
+  }
+
+  @Test
+  public void batchPut() throws Exception {
+
+    try (Table<String, String> testTable = createTypedTable(
+        "Fourth");
+        BatchOperation batch = rdbStore.initBatchOperation()) {
+      //given
+      String key =
+          RandomStringUtils.random(10);
+      String value =
+          RandomStringUtils.random(10);
+
+      //when
+      testTable.putWithBatch(batch, key, value);
+      rdbStore.commitBatchOperation(batch);
+
+      //then
+      Assert.assertNotNull(testTable.get(key));
+    }
+  }
+
+  @Test
+  public void batchDelete() throws Exception {
+    try (Table<String, String> testTable = createTypedTable(
+        "Fourth");
+        BatchOperation batch = rdbStore.initBatchOperation()) {
+
+      //given
+      String key =
+          RandomStringUtils.random(10);
+      String value =
+          RandomStringUtils.random(10);
+      testTable.put(key, value);
+
+      //when
+      testTable.deleteWithBatch(batch, key);
+      rdbStore.commitBatchOperation(batch);
+
+      //then
+      Assert.assertNull(testTable.get(key));
+    }
+  }
+
+  private static boolean consume(Table.KeyValue keyValue) {
+    count++;
+    Assert.assertNotNull(keyValue.getKey());
+    return true;
+  }
+
+  @Test
+  public void forEachAndIterator() throws Exception {
+    final int iterCount = 100;
+    try (Table<String, String> testTable = createTypedTable(
+        "Sixth")) {
+      for (int x = 0; x < iterCount; x++) {
+        String key =
+            RandomStringUtils.random(10);
+        String value =
+            RandomStringUtils.random(10);
+        testTable.put(key, value);
+      }
+      int localCount = 0;
+
+      try (TableIterator<String, ? extends KeyValue<String, String>> iter =
+          testTable.iterator()) {
+        while (iter.hasNext()) {
+          Table.KeyValue keyValue = iter.next();
+          localCount++;
+        }
+
+        Assert.assertEquals(iterCount, localCount);
+        iter.seekToFirst();
+        iter.forEachRemaining(TestTypedRDBTableStore::consume);
+        Assert.assertEquals(iterCount, count);
+
+      }
+    }
+  }
+}

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/OMMetadataManager.java

@@ -203,50 +203,50 @@ List<OmVolumeArgs> listVolumes(String userName, String prefix,
    *
    * @return UserTable.
    */
-  Table getUserTable();
+  Table<byte[], byte[]> getUserTable();
 
   /**
    * Returns the Volume Table.
    *
    * @return VolumeTable.
    */
-  Table getVolumeTable();
+  Table<byte[], byte[]> getVolumeTable();
 
   /**
    * Returns the BucketTable.
    *
    * @return BucketTable.
    */
-  Table getBucketTable();
+  Table<byte[], byte[]> getBucketTable();
 
   /**
    * Returns the KeyTable.
    *
    * @return KeyTable.
    */
-  Table getKeyTable();
+  Table<byte[], byte[]> getKeyTable();
 
   /**
    * Get Deleted Table.
    *
    * @return Deleted Table.
    */
-  Table getDeletedTable();
+  Table<byte[], byte[]> getDeletedTable();
 
   /**
    * Gets the OpenKeyTable.
    *
    * @return Table.
    */
-  Table getOpenKeyTable();
+  Table<byte[], byte[]> getOpenKeyTable();
 
   /**
    * Gets the S3Bucket to Ozone Volume/bucket mapping table.
    *
    * @return Table.
    */
-  Table getS3Table();
 
+  Table<byte[], byte[]> getS3Table();
   /**
    * Returns number of rows in a table.  This should not be used for very
    * large tables.
@@ -254,5 +254,6 @@ List<OmVolumeArgs> listVolumes(String userName, String prefix,
    * @return long
    * @throws IOException
    */
-  long countRowsInTable(Table table) throws IOException;
+  <KEY, VALUE> long countRowsInTable(Table<KEY, VALUE> table)
+      throws IOException;
 }

hadoop-ozone/integration-test/src/test/java/org/apache/hadoop/ozone/om/TestOzoneManager.java

@@ -58,6 +58,7 @@
 import org.apache.hadoop.ozone.web.response.ListVolumes;
 import org.apache.hadoop.util.Time;
 import org.apache.hadoop.utils.db.Table;
+import org.apache.hadoop.utils.db.Table.KeyValue;
 import org.apache.hadoop.utils.db.TableIterator;
 import org.junit.AfterClass;
 import org.junit.Assert;
@@ -652,8 +653,7 @@ public void testDeleteKey() throws IOException, OzoneException {
     // Make sure the deleted key has been moved to the deleted table.
     OMMetadataManager manager = cluster.getOzoneManager().
         getMetadataManager();
-
+    try (TableIterator<byte[], ? extends KeyValue<byte[], byte[]>> iter =
-    try(TableIterator<Table.KeyValue> iter =
             manager.getDeletedTable().iterator()) {
       iter.seekToFirst();
       Table.KeyValue kv = iter.next();

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OmMetadataManagerImpl.java

@@ -16,10 +16,16 @@
  */
 package org.apache.hadoop.ozone.om;
 
-import com.google.common.annotations.VisibleForTesting;
+import java.io.File;
-import com.google.common.base.Strings;
+import java.io.IOException;
-import com.google.common.collect.Lists;
+import java.nio.file.Paths;
-import org.apache.commons.lang3.StringUtils;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
 import org.apache.hadoop.hdds.client.BlockID;
 import org.apache.hadoop.hdds.conf.OzoneConfiguration;
 import org.apache.hadoop.hdfs.DFSUtil;
@@ -40,25 +46,20 @@
 import org.apache.hadoop.utils.db.DBStore;
 import org.apache.hadoop.utils.db.DBStoreBuilder;
 import org.apache.hadoop.utils.db.Table;
+import org.apache.hadoop.utils.db.Table.KeyValue;
 import org.apache.hadoop.utils.db.TableIterator;
-import org.eclipse.jetty.util.StringUtil;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.io.File;
-import java.io.IOException;
-import java.nio.file.Paths;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.stream.Collectors;
 
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
+import com.google.common.collect.Lists;
+import org.apache.commons.lang3.StringUtils;
 import static org.apache.hadoop.ozone.OzoneConfigKeys.OZONE_OPEN_KEY_EXPIRE_THRESHOLD_SECONDS;
 import static org.apache.hadoop.ozone.OzoneConfigKeys.OZONE_OPEN_KEY_EXPIRE_THRESHOLD_SECONDS_DEFAULT;
 import static org.apache.hadoop.ozone.OzoneConsts.OM_DB_NAME;
 import static org.apache.hadoop.ozone.OzoneConsts.OM_KEY_PREFIX;
+import org.eclipse.jetty.util.StringUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Ozone metadata manager interface.
@@ -122,37 +123,37 @@ public OmMetadataManagerImpl(OzoneConfiguration conf) throws IOException {
   }
 
   @Override
-  public Table getUserTable() {
+  public Table<byte[], byte[]> getUserTable() {
     return userTable;
   }
 
   @Override
-  public Table getVolumeTable() {
+  public Table<byte[], byte[]> getVolumeTable() {
     return volumeTable;
   }
 
   @Override
-  public Table getBucketTable() {
+  public Table<byte[], byte[]> getBucketTable() {
     return bucketTable;
   }
 
   @Override
-  public Table getKeyTable() {
+  public Table<byte[], byte[]> getKeyTable() {
     return keyTable;
   }
 
   @Override
-  public Table getDeletedTable() {
+  public Table<byte[], byte[]> getDeletedTable() {
     return deletedTable;
   }
 
   @Override
-  public Table getOpenKeyTable() {
+  public Table<byte[], byte[]> getOpenKeyTable() {
     return openKeyTable;
   }
 
   @Override
-  public Table getS3Table() {
+  public Table<byte[], byte[]> getS3Table() {
     return s3Table;
   }
 
@@ -349,8 +350,9 @@ private boolean startsWith(byte[] firstArray, byte[] secondArray) {
   @Override
   public boolean isVolumeEmpty(String volume) throws IOException {
     byte[] volumePrefix = getVolumeKey(volume + OM_KEY_PREFIX);
-    try (TableIterator<Table.KeyValue> bucketIter = bucketTable.iterator()) {
+    try (TableIterator<byte[], Table.KeyValue> bucketIter = bucketTable
-      Table.KeyValue kv = bucketIter.seek(volumePrefix);
+        .iterator()) {
+      Table.KeyValue<byte[], byte[]> kv = bucketIter.seek(volumePrefix);
       if (kv != null && startsWith(kv.getKey(), volumePrefix)) {
         return false; // we found at least one bucket with this volume prefix.
       }
@@ -370,8 +372,8 @@ public boolean isVolumeEmpty(String volume) throws IOException {
   public boolean isBucketEmpty(String volume, String bucket)
       throws IOException {
     byte[] keyPrefix = getBucketKey(volume, bucket + OM_KEY_PREFIX);
-    try (TableIterator<Table.KeyValue> keyIter = keyTable.iterator()) {
+    try (TableIterator<byte[], Table.KeyValue> keyIter = keyTable.iterator()) {
-      Table.KeyValue kv = keyIter.seek(keyPrefix);
+      Table.KeyValue<byte[], byte[]> kv = keyIter.seek(keyPrefix);
       if (kv != null && startsWith(kv.getKey(), keyPrefix)) {
         return false; // we found at least one key with this vol/bucket prefix.
       }
@@ -422,8 +424,9 @@ public List<OmBucketInfo> listBuckets(final String volumeName,
       seekPrefix = getVolumeKey(volumeName + OM_KEY_PREFIX);
     }
     int currentCount = 0;
-    try (TableIterator<Table.KeyValue> bucketIter = bucketTable.iterator()) {
+    try (TableIterator<byte[], Table.KeyValue> bucketIter = bucketTable
-      Table.KeyValue kv = bucketIter.seek(startKey);
+        .iterator()) {
+      Table.KeyValue<byte[], byte[]> kv = bucketIter.seek(startKey);
       while (currentCount < maxNumOfBuckets && bucketIter.hasNext()) {
         kv = bucketIter.next();
         // Skip the Start Bucket if needed.
@@ -483,8 +486,10 @@ public List<OmKeyInfo> listKeys(String volumeName, String bucketName,
       seekPrefix = getBucketKey(volumeName, bucketName + OM_KEY_PREFIX);
     }
     int currentCount = 0;
-    try (TableIterator<Table.KeyValue> keyIter = getKeyTable().iterator()) {
+    try (TableIterator<byte[], ? extends KeyValue<byte[], byte[]>> keyIter =
-      Table.KeyValue kv = keyIter.seek(seekKey);
+        getKeyTable()
+            .iterator()) {
+      Table.KeyValue<byte[], byte[]> kv = keyIter.seek(seekKey);
       while (currentCount < maxKeys && keyIter.hasNext()) {
         kv = keyIter.next();
         // Skip the Start key if needed.
@@ -578,10 +583,12 @@ private VolumeList getVolumesByUser(byte[] userNameKey)
   public List<BlockGroup> getPendingDeletionKeys(final int keyCount)
       throws IOException {
     List<BlockGroup> keyBlocksList = Lists.newArrayList();
-    try (TableIterator<Table.KeyValue> keyIter = getDeletedTable().iterator()) {
+    try (TableIterator<byte[], ? extends KeyValue<byte[], byte[]>> keyIter =
+        getDeletedTable()
+            .iterator()) {
       int currentCount = 0;
       while (keyIter.hasNext() && currentCount < keyCount) {
-        Table.KeyValue kv = keyIter.next();
+        KeyValue<byte[], byte[]> kv = keyIter.next();
         if (kv != null) {
           OmKeyInfo info =
               OmKeyInfo.getFromProtobuf(KeyInfo.parseFrom(kv.getValue()));
@@ -632,11 +639,12 @@ public List<BlockGroup> getExpiredOpenKeys() throws IOException {
   }
 
   @Override
-  public long countRowsInTable(Table table) throws IOException {
+  public <KEY, VALUE> long countRowsInTable(Table<KEY, VALUE> table)
+      throws IOException {
     long count = 0;
     if (table != null) {
-      try (TableIterator<Table.KeyValue> keyValueTableIterator =
+      try (TableIterator<KEY, ? extends KeyValue<KEY, VALUE>>
-               table.iterator()) {
+          keyValueTableIterator = table.iterator()) {
         while (keyValueTableIterator.hasNext()) {
           keyValueTableIterator.next();
           count++;