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.bookie.storage.ldb;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.Map.Entry;
  
  /**
   * Abstraction of a generic key-value local database.
   */
  public interface KeyValueStorage extends Closeable {
  
      void put(byte[] key, byte[] value) throws IOException;
  
      /**
       * Get the value associated with the given key.
       *
       * @param key
       *            the key to lookup
       * @return the value or null if the key was not found
       */
      byte[] get(byte[] key) throws IOException;
  
      /**
       * Get the value associated with the given key.
       *
       * <p>This method will use the provided array store the value
       *
       * @param key
       *            the key to lookup
       * @param value
       *            an array where to store the result
       * @return -1 if the entry was not found or the length of the value
       * @throws IOException
       *             if the value array could not hold the result
       */
      int get(byte[] key, byte[] value) throws IOException;
  
      /**
       * Get the entry whose key is the biggest and it's lesser than the supplied key.
       *
       * <p>For example if the db contains :
       *
       * <pre>
       * {
       *      1 : 'a',
       *      2 : 'b',
       *      3 : 'c'
       * }
       * </pre>
       *
       * <p>Then:
       *
       * <pre>
       * getFloor(3) --> (2, 'b')
       * </pre>
       *
       * @param key
       *            the non-inclusive upper limit key
       * @return the entry before or null if there's no entry before key
       */
      Entry<byte[], byte[]> getFloor(byte[] key) throws IOException;
  
      /**
       * Get the entry whose key is bigger or equal the supplied key.
       *
       * @param key
       * @return
       * @throws IOException
       */
      Entry<byte[], byte[]> getCeil(byte[] key) throws IOException;
  
      /**
       *
       * @param key
       * @throws IOException
       */
      void delete(byte[] key) throws IOException;
  
      /**
       * Compact storage within a specified range.
       *
       * @param firstKey
       *            the first key in the range (included)
       * @param lastKey
       *            the last key in the range (not included)
       */
      default void compact(byte[] firstKey, byte[] lastKey) throws IOException {}
  
      /**
       * Compact storage full range.
       */
      default void compact() throws IOException {}
  
      /**
       * Get storage path.
       */
      String getDBPath();
  
      /**
       * Get an iterator over to scan sequentially through all the keys in the
       * database.
       *
       * @return
       */
      CloseableIterator<byte[]> keys();
  
      /**
       * Get an iterator over to scan sequentially through all the keys within a
       * specified range.
       *
       * @param firstKey
       *            the first key in the range (included)
       * @param lastKey
       *            the lastKey in the range (not included)
       *
       */
      CloseableIterator<byte[]> keys(byte[] firstKey, byte[] lastKey);
  
      /**
       * Return an iterator object that can be used to sequentially scan through all
       * the entries in the database.
       */
      CloseableIterator<Entry<byte[], byte[]>> iterator();
  
      /**
       * Commit all pending write to durable storage.
       */
      void sync() throws IOException;
  
      /**
       * @return the number of keys.
       */
      long count() throws IOException;
  
      /**
       * Iterator interface.
       *
       * @param <T>
       */
      interface CloseableIterator<T> extends Closeable {
          boolean hasNext() throws IOException;
  
          T next() throws IOException;
      }
  
      Batch newBatch();
  
      /**
       * Interface for a batch to be written in the storage.
       */
      public interface Batch extends Closeable {
          void put(byte[] key, byte[] value) throws IOException;
  
          void remove(byte[] key) throws IOException;
  
          void deleteRange(byte[] beginKey, byte[] endKey) throws IOException;
  
          void clear();
  
          void flush() throws IOException;
  
          default int batchCount() {
              return -1;
          }
      }
  }
  