How to use

writeFields

method

in

org.apache.hadoop.hdfs.server.namenode.FSEditLogOp

 /**
  * Write an operation to the output stream
  * 
  * @param op The operation to write
  * @throws IOException if an error occurs during writing.
  */
 public void writeOp(FSEditLogOp op) throws IOException {
  int start = buf.getLength();
  // write the op code first to make padding and terminator verification
  // work
  buf.writeByte(op.opCode.getOpCode());
  buf.writeInt(0); // write 0 for the length first
  buf.writeLong(op.txid);
  op.writeFields(buf);
  int end = buf.getLength();
  
  // write the length back: content of the op + 4 bytes checksum - op_code
  int length = end - start - 1;
  buf.writeInt(length, start + 1);
  checksum.reset();
  checksum.update(buf.getData(), start, end-start);
  int sum = (int)checksum.getValue();
  buf.writeInt(sum);
 }
}

 /**
  * Write an operation to the output stream
  * 
  * @param op The operation to write
  * @throws IOException if an error occurs during writing.
  */
 public void writeOp(FSEditLogOp op) throws IOException {
  int start = buf.getLength();
  buf.writeByte(op.opCode.getOpCode());
  buf.writeLong(op.txid);
  op.writeFields(buf);
  int end = buf.getLength();
  Checksum checksum = FSEditLog.getChecksumForWrite();
  checksum.reset();
  checksum.update(buf.getData(), start, end-start);
  int sum = (int)checksum.getValue();
  buf.writeInt(sum);
 }
}

 /**
  * Write an operation to the output stream
  * 
  * @param op The operation to write
  * @throws IOException if an error occurs during writing.
  */
 public void writeOp(FSEditLogOp op) throws IOException {
  int start = buf.getLength();
  // write the op code first to make padding and terminator verification
  // work
  buf.writeByte(op.opCode.getOpCode());
  buf.writeInt(0); // write 0 for the length first
  buf.writeLong(op.txid);
  op.writeFields(buf);
  int end = buf.getLength();
  
  // write the length back: content of the op + 4 bytes checksum - op_code
  int length = end - start - 1;
  buf.writeInt(length, start + 1);
  checksum.reset();
  checksum.update(buf.getData(), start, end-start);
  int sum = (int)checksum.getValue();
  buf.writeInt(sum);
 }
}

 /**
  * Write an operation to the output stream
  * 
  * @param op The operation to write
  * @throws IOException if an error occurs during writing.
  */
 public void writeOp(FSEditLogOp op) throws IOException {
  int start = buf.getLength();
  // write the op code first to make padding and terminator verification
  // work
  buf.writeByte(op.opCode.getOpCode());
  buf.writeInt(0); // write 0 for the length first
  buf.writeLong(op.txid);
  op.writeFields(buf);
  int end = buf.getLength();
  
  // write the length back: content of the op + 4 bytes checksum - op_code
  int length = end - start - 1;
  buf.writeInt(length, start + 1);
  checksum.reset();
  checksum.update(buf.getData(), start, end-start);
  int sum = (int)checksum.getValue();
  buf.writeInt(sum);
 }
}