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.carbondata.core.datastore;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  
  public interface FileReader {
  
    /**
     * This method will be used to reads the data to byteBuffer from file based on offset
     * and length(number of bytes) need to read
     *
     * @param filePath fully qualified file path
     * @param offset reading start position,
     * @param length number of bytes to be read
     * @return ByteBuffer
     * @throws IOException
     */
    ByteBuffer readByteBuffer(String filePath, long offset, int length)
        throws IOException;
  
    /**
     * This method will be used to read the byte array from file based on offset
     * and length(number of bytes) need to read
     *
     * @param filePath fully qualified file path
     * @param offset   reading start position,
     * @param length   number of bytes to be read
     * @return read byte array
     */
    byte[] readByteArray(String filePath, long offset, int length) throws IOException;
  
    /**
     * This method will be used to read the byte array from file based on length(number of bytes)
     *
     * @param filePath fully qualified file path
     * @param length   number of bytes to be read
     * @return read byte array
     */
    byte[] readByteArray(String filePath, int length) throws IOException;
  
    /**
     * This method will be used to read int from file from position(offset), here
     * length will be always 4 because int byte size if 4
     *
     * @param filePath fully qualified file path
     * @param offset   reading start position,
     * @return read int
     */
    int readInt(String filePath, long offset) throws IOException;
  
    /**
     * This method will be used to read long from file from position(offset), here
     * length will be always 8 because int byte size is 8
     *
     * @param filePath fully qualified file path
     * @param offset   reading start position,
     * @return read long
     */
    long readLong(String filePath, long offset) throws IOException;
  
    /**
     * This method will be used to read int from file from position(offset), here
     * length will be always 4 because int byte size if 4
     *
     * @param filePath fully qualified file path
     * @return read int
     */
    int readInt(String filePath) throws IOException;
  
    /**
     * This method will be used to read long value from file from position(offset), here
     * length will be always 8 because long byte size if 4
     *
     * @param filePath fully qualified file path
     * @param offset   reading start position,
     * @return read long
     */
    long readDouble(String filePath, long offset) throws IOException;
  
    /**
     * This method will be used to close all the streams currently present in the cache
     */
    void finish() throws IOException;
  
    /**
     * Set the flag to read data page by page instead of whole blocklet.
     *
     * @param isReadPageByPage
     */
    void setReadPageByPage(boolean isReadPageByPage);
  
    /**
     * Whether read the data page by page from carbondata file instead of reading whole
     * blocklet to memory. It is need in case of memory constraint operations.
     */
    boolean isReadPageByPage();
  
  }