content: /**
   * Copyright 2011 The Apache Software Foundation
   *
   * 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.wasp.fserver;
  
  import com.alibaba.wasp.EntityGroupInfo;
  import com.alibaba.wasp.protobuf.generated.ClientProtos.QueryResultProto;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.List;
  
  public interface InternalScanner extends Closeable {
  
    /**
     * @return The EntityGroupInfo for this scanner.
     */
    public EntityGroupInfo getEntityGroupInfo();
  
    /**
     * Grab the next row's worth of values.
     * 
     * @param results
     *          return output array
     * @return true if more rows exist after this one, false if scanner is done
     * @throws java.io.IOException
     *           e
     */
    public boolean next(List<QueryResultProto> results) throws IOException;
  
    /**
     * Grab the next row's worth of values.
     *
     * @param results
     *          return output array
     * @param metric
     *          the metric name
     * @return true if more rows exist after this one, false if scanner is done
     * @throws java.io.IOException
     *           e
     */
    public boolean next(List<QueryResultProto> results, String metric) throws IOException;
  
  
    /**
     * Closes the scanner and releases any resources it has allocated
     *
     * @throws java.io.IOException
     */
    public void close() throws IOException;
  }
  