package com.avaje.ebeaninternal.server.cluster;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;

/**
 * Represents a relatively small independent message.
 * <p>
 * In general terms we break up a potentially large object like
 * RemoteTransactionEvent into many smaller BinaryMessages. This is so that if
 * they don't all fit on a single Packet we can easily break them up and put
 * them on multiple packets.
 * </p>
 * <p>
 * Also note that for the Multicast approach a Packet will generally contain
 * many messages each directed to different members of the cluster. So it would
 * be common for many Ack, Resend and Control messages to all be contained in a
 * single packet.
 * </p>
 */
public class BinaryMessage {

  public static final int TYPE_MSGCONTROL = 0;
  public static final int TYPE_BEANIUD = 1;
  public static final int TYPE_TABLEIUD = 2;

  public static final int TYPE_MSGACK = 8;
  public static final int TYPE_MSGRESEND = 9;

  private final ByteArrayOutputStream buffer;
  private final DataOutputStream os;
  private byte[] bytes;

  /**
   * Create with an estimated buffer size.
   */
  public BinaryMessage(int bufSize) {
    this.buffer = new ByteArrayOutputStream(bufSize);
    this.os = new DataOutputStream(buffer);
  }

  /**
   * Return the DataOutputStream to write content to.
   */
  public DataOutputStream getOs() {
    return os;
  }

  /**
   * Return all the content as a byte array.
   */
  public byte[] getByteArray() {
    if (bytes == null) {
      bytes = buffer.toByteArray();
    }
    return bytes;
  }
}
