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 com.alibaba.jstorm.cache.rocksdb;
  
  import backtype.storm.state.Serializer;
  import com.alibaba.jstorm.cache.IKvStore;
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.collect.Maps;
  import org.rocksdb.*;
  import org.slf4j.*;
  
  import java.io.IOException;
  import java.util.Map;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * Class that creates and restores {@link IKvStore IKvStores} in RocksDB.
   */
  public class RocksDbKvStoreManager {
      private static final org.slf4j.Logger LOG = LoggerFactory.getLogger(RocksDbKvStoreManager.class);
  
      private final RocksDB rocksDB;
      private final ColumnFamilyOptions columnOptions;
      private final Serializer<Object> serializer;
      private final Map<String, ColumnFamilyHandle> columnFamilies;
  
      @VisibleForTesting
      public RocksDbKvStoreManager(RocksDB rocksDB, ColumnFamilyOptions columnOptions, Serializer<Object> serializer) {
          this.rocksDB = checkNotNull(rocksDB, "rocksDB");
          this.columnOptions = checkNotNull(columnOptions, "columnOptions");
          this.serializer = checkNotNull(serializer, "serializer");
          this.columnFamilies = Maps.newHashMap();
      }
  
      public <K, V> IKvStore<K, V> getOrCreate(String kvStoreId) throws IOException {
          // TODO: restore IKvStores in failures recovery.
          return RocksDbKvStoreFactory.rocksDbCache(rocksDB, getOrCreateColumnFamily(kvStoreId), serializer);
      }
  
      private ColumnFamilyHandle getOrCreateColumnFamily(String kvStoreId) throws IOException {
          ColumnFamilyHandle columnFamily = columnFamilies.get(kvStoreId);
          // TODO: verify existing column family is compatible with the request.
          if (columnFamily == null) {
              ColumnFamilyDescriptor columnDescriptor =
                      new ColumnFamilyDescriptor(kvStoreId.getBytes(), columnOptions);
              try {
                  columnFamily = rocksDB.createColumnFamily(columnDescriptor);
                  columnFamilies.put(kvStoreId, columnFamily);
              } catch (RocksDBException e) {
                  throw new IOException("Error creating ColumnFamilyHandle.", e);
              }
          }
          return columnFamily;
      }
  
      public void close() {
          try {
              this.rocksDB.flush(new FlushOptions());
          } catch (RocksDBException e) {
              LOG.warn("Failed to flush db before cleanup", e);
          }
          this.rocksDB.dispose();
      }
  }
  