src/main/java/com/sleepycat/je/log/Loggable.java

/*-
 * Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
 *
 * This file was distributed by Oracle as part of a version of Oracle Berkeley
 * DB Java Edition made available at:
 *
 * http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
 *
 * Please see the LICENSE file included in the top-level directory of the
 * appropriate version of Oracle Berkeley DB Java Edition for a copy of the
 * license and additional information.
 */

package com.sleepycat.je.log;

import java.nio.ByteBuffer;

/**
 * A class that implements Loggable knows how to read and write itself into
 * a ByteBuffer in a format suitable for the JE log or JE replication
 * messages.
 *
 * <p>Classes that implement {@code Loggable} and are included in replication
 * data should implement {@code VersionedWriteLoggable}.
 */
public interface Loggable {

    /*
     * Writing to a byte buffer
     */

    /**
     * @return number of bytes used to store this object.
     */
    public int getLogSize();

    /**
     * Serialize this object into the buffer.
     * @param logBuffer is the destination buffer
     */
    public void writeToLog(ByteBuffer logBuffer);

    /*
     *  Reading from a byte buffer
     */

    /**
     * Initialize this object from the data in itemBuf.
     * @param itemBuffer the source buffer
     * @param entryVersion the log version of the data
     */
    public void readFromLog(ByteBuffer itemBuffer, int entryVersion);

    /**
     * Write the object into the string buffer for log dumping. Each object
     * should be dumped without indentation or new lines and should be valid
     * XML.
     * @param sb destination string buffer
     * @param verbose if true, dump the full, verbose version
     */
    public void dumpLog(StringBuilder sb, boolean verbose);

    /**
     * @return the transaction id embedded within this loggable object. Objects
     * that have no transaction id should return 0.
     */
    public long getTransactionId();

    /**
     * @return true if these two loggable items are logically the same.
     * Used for replication testing.
     */
    public boolean logicalEquals(Loggable other);
}