ObjectStreamEncoder.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.encoder;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import ch.qos.logback.core.CoreConstants;

/**
 * Write out events as java objects.
 *
 * @author Ceki Gülcü
 *
 * @param <E> type of log event object
 */
public class ObjectStreamEncoder<E> extends EncoderBase<E> {

  static public final int START_PEBBLE = 1853421169;
  static public final int STOP_PEBBLE = 640373619;

  private int MAX_BUFFER_SIZE = 100;

  List<E> bufferList = new ArrayList<E>(MAX_BUFFER_SIZE);

  public void doEncode(E event) throws IOException {
    bufferList.add(event);
    if (bufferList.size() == MAX_BUFFER_SIZE) {
      writeBuffer();
    }
  }

  void writeHeader(ByteArrayOutputStream baos, int bufferSize) {
    ByteArrayUtil.writeInt(baos, START_PEBBLE);
    ByteArrayUtil.writeInt(baos, bufferSize);
    ByteArrayUtil.writeInt(baos, 0);
    ByteArrayUtil.writeInt(baos, START_PEBBLE^bufferSize);
  }

  void writeFooter(ByteArrayOutputStream baos, int bufferSize) {
    ByteArrayUtil.writeInt(baos, STOP_PEBBLE);
    ByteArrayUtil.writeInt(baos, STOP_PEBBLE ^ bufferSize);
  }
  void writeBuffer() throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream(10000);

    int size = bufferList.size();
    writeHeader(baos, size);
    ObjectOutputStream oos = new ObjectOutputStream(baos);
    for (E e : bufferList) {
      oos.writeObject(e);
    }
    bufferList.clear();
    oos.flush();

    writeFooter(baos, size);

    byte[] byteArray = baos.toByteArray();
    oos.close();
    writeEndPosition(byteArray);
    outputStream.write(byteArray);

  }

  void writeEndPosition(byte[] byteArray) {
    int offset = 2*CoreConstants.BYTES_PER_INT;
    ByteArrayUtil.writeInt(byteArray,offset, byteArray.length-offset);
  }

  @Override
  public void init(OutputStream os) throws IOException {
    super.init(os);
    bufferList.clear();
  }

  public void close() throws IOException {
    writeBuffer();
  }
}