IFile.java 文件源码

/**
 * Construct an IFile Reader.
 * 
 * @param conf Configuration File 
 * @param in   The input stream
 * @param length Length of the data in the stream, including the checksum
 *               bytes.
 * @param codec codec
 * @param readsCounter Counter for records read from disk
 * @throws IOException
 */
public Reader(Configuration conf, FSDataInputStream in, long length, 
              CompressionCodec codec,
              Counters.Counter readsCounter) throws IOException {
  readRecordsCounter = readsCounter;
  checksumIn = new IFileInputStream(in,length, conf);
  if (codec != null) {
    decompressor = CodecPool.getDecompressor(codec);
    if (decompressor != null) {
      this.in = codec.createInputStream(checksumIn, decompressor);
    } else {
      LOG.warn("Could not obtain decompressor from CodecPool");
      this.in = checksumIn;
    }
  } else {
    this.in = checksumIn;
  }
  this.dataIn = new DataInputStream(this.in);
  this.fileLength = length;

  if (conf != null) {
    bufferSize = conf.getInt("io.file.buffer.size", DEFAULT_BUFFER_SIZE);
  }
}