content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * Licensed 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
   *
   * https://opensource.org/licenses/Apache-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.tencent.angel.worker.storage;
  
  import java.io.IOException;
  
  /**
   * The interface Reader.
   *
   * @param <K> the KEY type
   * @param <V> the VALUE type
   */
  public interface Reader<K, V> {
  
    /**
     * Read the next key, value pair
     *
     * @return true if a key/value pair was read
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    boolean nextKeyValue() throws IOException, InterruptedException;
  
    /**
     * Gets current key.
     *
     * @return the current key
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    K getCurrentKey() throws IOException, InterruptedException;
  
    /**
     * Gets current value.
     *
     * @return the current value
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    V getCurrentValue() throws IOException, InterruptedException;
  
    /**
     * Reset the Reader position to beginning
     *
     * @throws IOException
     */
    void reset() throws IOException;
  
    /**
     * Close.
     *
     * @throws IOException
     */
    void close() throws IOException;
  
    /**
     * Gets progress.
     *
     * @return the progress
     */
    float getProgress();
  }