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.reader;
  
  import java.io.ByteArrayInputStream;
  import java.io.DataInputStream;
  import java.io.IOException;
  
  import org.apache.carbondata.core.datastore.impl.FileFactory;
  import org.apache.carbondata.core.util.CarbonUtil;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataInputStream;
  import org.apache.thrift.TBase;
  import org.apache.thrift.TException;
  import org.apache.thrift.protocol.TCompactProtocol;
  import org.apache.thrift.protocol.TProtocol;
  import org.apache.thrift.transport.TIOStreamTransport;
  import org.apache.thrift.transport.TTransportException;
  
  /**
   * A simple class for reading Thrift objects (of a single type) from a fileName.
   */
  public class ThriftReader {
    /**
     * File containing the objects.
     */
    private String fileName;
    /**
     * Used to create empty objects that will be initialized with values from the fileName.
     */
    private TBaseCreator creator;
    /**
     * For reading the fileName.
     */
    private DataInputStream dataInputStream;
    /**
     * For reading the binary thrift objects.
     */
    private TProtocol binaryIn;
  
    private Configuration configuration;
  
    /**
     * Constructor.
     */
    public ThriftReader(String fileName, TBaseCreator creator) {
      this.fileName = fileName;
      this.creator = creator;
    }
  
    public ThriftReader(String fileName, TBaseCreator creator, Configuration configuration) {
      this.fileName = fileName;
      this.configuration = configuration;
      this.creator = creator;
    }
  
    /**
     * Constructor.
     */
    public ThriftReader(String fileName) {
      this.fileName = fileName;
    }
  
    /**
     * Constructor.
     */
    public ThriftReader(String fileName, Configuration configuration) {
      this.fileName = fileName;
      this.configuration = configuration;
    }
  
    /**
     * Constructor.
     */
    public ThriftReader(byte[] fileData) {
      dataInputStream = new DataInputStream(new ByteArrayInputStream(fileData));
      try {
        binaryIn = new TCompactProtocol(new TIOStreamTransport(dataInputStream));
      } catch (TTransportException e) {
        throw new RuntimeException(e);
      }
    }
  
    /**
     * Opens the fileName for reading.
     */
    public void open() throws IOException {
      Configuration conf = configuration != null ? configuration : FileFactory.getConfiguration();
      dataInputStream = FileFactory.getDataInputStream(fileName, conf);
      try {
        binaryIn = new TCompactProtocol(new TIOStreamTransport(dataInputStream));
      } catch (TTransportException e) {
        throw new IOException(e);
      }
    }
  
    /**
     * This method will set the position of stream from where data has to be read
     */
    public void setReadOffset(long bytesToSkip) throws IOException {
      if (dataInputStream instanceof FSDataInputStream) {
        ((FSDataInputStream)dataInputStream).seek(bytesToSkip);
      } else if (dataInputStream.skip(bytesToSkip) != bytesToSkip) {
        throw new IOException("It doesn't set the offset properly");
      }
    }
  
    /**
     * Checks if another objects is available by attempting to read another byte from the stream.
     */
    public boolean hasNext() throws IOException {
      return dataInputStream.available() > 0;
    }
  
    /**
     * Reads the next object from the fileName.
     */
    public TBase read() throws IOException {
      TBase t = creator.create();
      try {
        t.read(binaryIn);
      } catch (TException e) {
        throw new IOException(e);
      }
      return t;
    }
  
    /**
     * Reads the next object from the fileName.
     *
     * @param creator type of object which will be returned
     * @throws IOException any problem while reading
     */
    public TBase read(TBaseCreator creator) throws IOException {
      TBase t = creator.create();
      try {
        t.read(binaryIn);
      } catch (TException e) {
        throw new IOException(e);
      }
      return t;
    }
  
    /**
     * Close the fileName.
     */
    public void close() {
      CarbonUtil.closeStreams(dataInputStream);
    }
  
    /**
     * Thrift deserializes by taking an existing object and populating it. ThriftReader
     * needs a way of obtaining instances of the class to be populated and this interface
     * defines the mechanism by which a client provides these instances.
     */
    public interface TBaseCreator {
      TBase create();
    }
  }
  