content: /*
   * 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.bookkeeper.statelib.impl.kv;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufUtil;
  import io.netty.buffer.Unpooled;
  import io.netty.util.ReferenceCountUtil;
  import java.io.IOException;
  import java.util.concurrent.CompletableFuture;
  import java.util.function.Supplier;
  import org.apache.bookkeeper.common.coder.Coder;
  import org.apache.bookkeeper.common.concurrent.FutureUtils;
  import org.apache.bookkeeper.proto.statestore.kv.Command;
  import org.apache.bookkeeper.statelib.api.StateStoreSpec;
  import org.apache.bookkeeper.statelib.api.exceptions.InvalidStateStoreException;
  import org.apache.bookkeeper.statelib.api.kv.KVAsyncStore;
  import org.apache.bookkeeper.statelib.impl.journal.AbstractStateStoreWithJournal;
  import org.apache.bookkeeper.statelib.impl.journal.CommandProcessor;
  import org.apache.distributedlog.api.namespace.Namespace;
  
  /**
   * A async kv store implementation.
   */
  public class RocksdbKVAsyncStore<K, V>
      extends AbstractStateStoreWithJournal<RocksdbKVStore<byte[], byte[]>>
      implements KVAsyncStore<K, V> {
  
      private static final byte[] CATCHUP_MARKER = new byte[0];
  
      private Coder<K> keyCoder;
      private Coder<V> valCoder;
  
      public RocksdbKVAsyncStore(Supplier<RocksdbKVStore<byte[], byte[]>> localStateStoreSupplier,
                                 Supplier<Namespace> namespaceSupplier) {
          super(localStateStoreSupplier, namespaceSupplier);
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public CompletableFuture<Void> init(StateStoreSpec spec) {
          this.keyCoder = (Coder<K>) spec.getKeyCoder();
          this.valCoder = (Coder<V>) spec.getValCoder();
  
          return super.init(spec);
      }
  
      @Override
      public CompletableFuture<V> get(K key) {
          synchronized (this) {
              if (!isInitialized) {
                  return uninitializedException();
              }
          }
  
          return executeReadIO(() -> {
              byte[] keyBytes = keyCoder.encode(key);
              byte[] valBytes = localStore.get(keyBytes);
              if (null == valBytes) {
                  return null;
              } else {
                  return KVUtils.deserialize(valCoder, Unpooled.wrappedBuffer(valBytes));
              }
          });
      }
  
      @Override
      public CompletableFuture<Void> put(K key, V value) {
          synchronized (this) {
              if (!isInitialized) {
                  return uninitializedException();
              }
          }
  
          byte[] keyBytes = keyCoder.encode(key);
          byte[] valBytes = valCoder.encode(value);
  
          Command command = Command.newBuilder()
              .setPutReq(KVUtils.newPutRequest(keyBytes, valBytes))
              .build();
          return writeCommandReturnTxId(command).thenApplyAsync((revision) -> {
              ByteBuf serializedBuf = KVUtils.serialize(valBytes, revision);
              try {
                  byte[] serializedBytes = ByteBufUtil.getBytes(serializedBuf);
                  localStore.put(keyBytes, serializedBytes, revision);
              } finally {
                  ReferenceCountUtil.release(serializedBuf);
              }
              return null;
          }, writeIOScheduler);
      }
  
      @Override
      public CompletableFuture<V> putIfAbsent(K key, V value) {
  
          byte[] keyBytes = keyCoder.encode(key);
          byte[] valBytes = valCoder.encode(value);
  
          Command command = Command.newBuilder()
              .setPutIfAbsentReq(KVUtils.newPutIfAbsentRequest(keyBytes, valBytes))
              .build();
          return writeCommandReturnTxId(command).thenApplyAsync((revision) -> {
              ByteBuf serializedBuf = KVUtils.serialize(valBytes, revision);
              try {
                  byte[] serializedBytes = ByteBufUtil.getBytes(serializedBuf);
                  byte[] prevValue = localStore.putIfAbsent(keyBytes, serializedBytes, revision);
                  if (null == prevValue) {
                      return null;
                  } else {
                      return KVUtils.deserialize(valCoder, Unpooled.wrappedBuffer(prevValue));
                  }
              } finally {
                  ReferenceCountUtil.release(serializedBuf);
              }
          }, writeIOScheduler);
      }
  
      @Override
      public CompletableFuture<V> delete(K key) {
          byte[] keyBytes = keyCoder.encode(key);
  
          Command command = Command.newBuilder()
              .setDelReq(KVUtils.newDeleteRequest(keyBytes))
              .build();
          return writeCommandReturnTxId(command).thenApplyAsync((revision) -> {
              byte[] prevValue = localStore.delete(keyBytes, revision);
              if (null == prevValue) {
                  return null;
              } else {
                  return KVUtils.deserialize(valCoder, Unpooled.wrappedBuffer(prevValue));
              }
          }, writeIOScheduler);
      }
  
      private <AnyT> CompletableFuture<AnyT> uninitializedException() {
          return FutureUtils.exception(
              new InvalidStateStoreException("State store " + name() + " is not initialized yet."));
      }
  
      //
      // Journaled State Store interfaces
      //
  
      @Override
      protected ByteBuf newCatchupMarker() {
          return Unpooled.wrappedBuffer(CATCHUP_MARKER);
      }
  
      @Override
      protected CommandProcessor<RocksdbKVStore<byte[], byte[]>> newCommandProcessor() {
          return KVCommandProcessor.of();
      }
  
      private CompletableFuture<Long> writeCommandReturnTxId(Command command) {
          try {
              ByteBuf cmdBuf = KVUtils.newCommandBuf(command);
              return writeCommandBufReturnTxId(cmdBuf);
          } catch (IOException e) {
              return FutureUtils.exception(e);
          }
      }
  }
  