/*
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* The contents of this file are subject to the terms of the Common Development and
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* Distribution License (the License). You may not use this file except in compliance with the
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* License.
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*
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* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
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* specific language governing permission and limitations under the License.
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*
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* When distributing Covered Software, include this CDDL Header Notice in each file and include
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* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
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* Header, with the fields enclosed by brackets [] replaced by your own identifying
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* information: "Portions Copyright [year] [name of copyright owner]".
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*
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* Copyright 2006-2009 Sun Microsystems, Inc.
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* Portions Copyright 2013-2015 ForgeRock AS.
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*/
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package org.opends.server.replication.common;
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import java.io.Serializable;
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import java.util.Date;
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import org.forgerock.opendj.ldap.ByteSequence;
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import org.forgerock.opendj.ldap.ByteSequenceReader;
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import org.forgerock.opendj.ldap.ByteString;
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import org.forgerock.opendj.ldap.ByteStringBuilder;
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/**
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* Class used to represent Change Sequence Numbers.
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*
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* @see <a href="http://tools.ietf.org/html/draft-ietf-ldup-infomod-08"
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* >Inspiration for this class comes from LDAPChangeSequenceNumber</a>
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*/
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public class CSN implements Serializable, Comparable<CSN>
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{
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/**
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* The number of bytes used by the byte string representation of a change
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* number.
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*
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* @see #valueOf(ByteSequence)
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* @see #toByteString()
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* @see #toByteString(ByteStringBuilder)
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*/
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public static final int BYTE_ENCODING_LENGTH = 14;
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/**
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* The number of characters used by the string representation of a change
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* number.
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*
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* @see #valueOf(String)
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* @see #toString()
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*/
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public static final int STRING_ENCODING_LENGTH = 28;
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/** The maximum possible value for a CSN. */
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public static final CSN MAX_CSN_VALUE = new CSN(Long.MAX_VALUE, Integer.MAX_VALUE, Short.MAX_VALUE);
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private static final long serialVersionUID = -8802722277749190740L;
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private final long timeStamp;
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/**
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* The sequence number is set to zero at the start of each millisecond, and
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* incremented by one for each update operation that occurs within that
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* millisecond. It allows to distinguish changes that have been done in the
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* same millisecond.
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*/
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private final int seqnum;
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private final int serverId;
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/**
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* Parses the provided {@link #toString()} representation of a CSN.
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*
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* @param s
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* The string to be parsed.
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* @return The parsed CSN.
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* @see #toString()
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*/
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public static CSN valueOf(String s)
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{
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return new CSN(s);
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}
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/**
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* Decodes the provided {@link #toByteString()} representation of a change
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* number.
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*
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* @param bs
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* The byte sequence to be parsed.
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* @return The decoded CSN.
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* @see #toByteString()
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*/
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public static CSN valueOf(ByteSequence bs)
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{
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ByteSequenceReader reader = bs.asReader();
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long timeStamp = reader.readLong();
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int serverId = reader.readShort() & 0xffff;
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int seqnum = reader.readInt();
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return new CSN(timeStamp, seqnum, serverId);
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}
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/**
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* Create a new {@link CSN} from a String.
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*
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* @param str
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* the string from which to create a {@link CSN}
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*/
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public CSN(String str)
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{
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String temp = str.substring(0, 16);
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timeStamp = Long.parseLong(temp, 16);
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temp = str.substring(16, 20);
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serverId = Integer.parseInt(temp, 16);
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temp = str.substring(20, 28);
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seqnum = Integer.parseInt(temp, 16);
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}
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/**
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* Create a new {@link CSN}.
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*
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* @param timeStamp
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* timeStamp for the {@link CSN}
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* @param seqNum
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* sequence number
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* @param serverId
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* identity of server
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*/
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public CSN(long timeStamp, int seqNum, int serverId)
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{
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this.serverId = serverId;
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this.timeStamp = timeStamp;
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this.seqnum = seqNum;
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}
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/**
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* Getter for the time.
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*
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* @return the time
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*/
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public long getTime()
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{
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return timeStamp;
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}
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/**
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* Get the timestamp associated to this {@link CSN} in seconds.
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*
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* @return timestamp associated to this {@link CSN} in seconds
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*/
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public long getTimeSec()
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{
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return timeStamp / 1000;
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}
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/**
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* Getter for the sequence number.
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*
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* @return the sequence number
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*/
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public int getSeqnum()
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{
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return seqnum;
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}
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/**
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* Getter for the server ID.
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*
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* @return the server ID
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*/
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public int getServerId()
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{
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return serverId;
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}
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@Override
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public boolean equals(Object obj)
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{
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if (this == obj)
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{
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return true;
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}
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else if (obj instanceof CSN)
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{
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final CSN csn = (CSN) obj;
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return this.seqnum == csn.seqnum && this.serverId == csn.serverId
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&& this.timeStamp == csn.timeStamp;
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}
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else
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{
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return false;
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}
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}
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@Override
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public int hashCode()
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{
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return this.seqnum + this.serverId + Long.valueOf(timeStamp).hashCode();
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}
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/**
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* Encodes this CSN as a byte string.
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* <p>
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* NOTE: this representation must not be modified otherwise interop with
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* earlier protocol versions will be broken.
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*
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* @return The encoded representation of this CSN.
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* @see #valueOf(ByteSequence)
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*/
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public ByteString toByteString()
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{
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final ByteStringBuilder builder = new ByteStringBuilder(BYTE_ENCODING_LENGTH);
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toByteString(builder);
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return builder.toByteString();
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}
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/**
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* Encodes this CSN into the provided byte string builder.
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* <p>
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* NOTE: this representation must not be modified otherwise interop with
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* earlier protocol versions will be broken.
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*
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* @param builder
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* The byte string builder.
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* @see #valueOf(ByteSequence)
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*/
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public void toByteString(ByteStringBuilder builder)
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{
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builder.appendLong(timeStamp).appendShort(serverId & 0xffff).appendInt(seqnum);
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}
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/**
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* Convert the {@link CSN} to a printable String.
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* <p>
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* NOTE: this representation must not be modified otherwise interop with
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* earlier protocol versions will be broken.
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*
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* @return the string
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*/
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@Override
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public String toString()
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{
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final StringBuilder buffer = new StringBuilder();
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toString(buffer);
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return buffer.toString();
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}
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/**
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* Appends the text representation of this {@link CSN} into the provided StringBuilder.
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* <p>
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* NOTE: this representation must not be modified otherwise interop with
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* earlier protocol versions will be broken.
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*
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* @param buffer the StringBuilder where to output the CSN text representation
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*/
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void toString(final StringBuilder buffer)
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{
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leftPadWithZeros(buffer, 16, Long.toHexString(timeStamp));
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leftPadWithZeros(buffer, 4, Integer.toHexString(serverId));
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leftPadWithZeros(buffer, 8, Integer.toHexString(seqnum));
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}
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private void leftPadWithZeros(StringBuilder buffer, int nbChars, String toAppend)
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{
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final int padding = nbChars - toAppend.length();
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for (int i = 0; i < padding; i++)
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{
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buffer.append('0');
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}
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buffer.append(toAppend);
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}
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/**
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* Convert the {@link CSN} to a printable String with a user friendly format.
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*
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* @return the string
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*/
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public String toStringUI()
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{
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final StringBuilder buffer = new StringBuilder();
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toStringUI(buffer);
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return buffer.toString();
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}
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private void toStringUI(final StringBuilder buffer)
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{
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toString(buffer);
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buffer.append(" (sid=").append(serverId)
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.append(",tsd=").append(new Date(timeStamp))
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.append(",ts=").append(timeStamp)
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.append(",seqnum=").append(seqnum)
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.append(")");
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}
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/**
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* Compares this CSN with the provided CSN for order and returns a negative
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* number if {@code csn1} is older than {@code csn2}, zero if they have the
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* same age, or a positive number if {@code csn1} is newer than {@code csn2}.
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*
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* @param csn1
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* The first CSN to be compared, which may be {@code null}.
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* @param csn2
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* The second CSN to be compared, which may be {@code null}.
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* @return A negative number if {@code csn1} is older than {@code csn2}, zero
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* if they have the same age, or a positive number if {@code csn1} is
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* newer than {@code csn2}.
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*/
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public static int compare(CSN csn1, CSN csn2)
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{
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if (csn1 == null)
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{
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return csn2 == null ? 0 : -1;
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}
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else if (csn2 == null)
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{
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return 1;
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}
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else if (csn1.timeStamp != csn2.timeStamp)
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{
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return csn1.timeStamp < csn2.timeStamp ? -1 : 1;
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}
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else if (csn1.seqnum != csn2.seqnum)
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{
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return csn1.seqnum - csn2.seqnum;
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}
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else
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{
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return csn1.serverId - csn2.serverId;
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}
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}
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/**
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* Computes the difference in number of changes between 2 CSNs. First one is
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* expected to be newer than second one. If this is not the case, 0 will be
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* returned.
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*
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* @param csn1
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* the first {@link CSN}
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* @param csn2
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* the second {@link CSN}
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* @return the difference
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*/
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public static int diffSeqNum(CSN csn1, CSN csn2)
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{
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if (csn1 == null)
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{
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return 0;
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}
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if (csn2 == null)
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{
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return csn1.getSeqnum();
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}
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if (csn2.isNewerThanOrEqualTo(csn1))
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{
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return 0;
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}
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int seqnum1 = csn1.getSeqnum();
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long time1 = csn1.getTime();
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int seqnum2 = csn2.getSeqnum();
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long time2 = csn2.getTime();
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if (time2 <= time1)
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{
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if (seqnum2 <= seqnum1)
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{
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return seqnum1 - seqnum2;
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}
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return Integer.MAX_VALUE - (seqnum2 - seqnum1) + 1;
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}
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return 0;
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}
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/**
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* Returns {@code true} if this CSN is older than the provided CSN.
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*
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* @param csn
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* The CSN to be compared.
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* @return {@code true} if this CSN is older than the provided CSN.
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*/
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public boolean isOlderThan(CSN csn)
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{
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return compare(this, csn) < 0;
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}
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/**
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* Returns {@code true} if this CSN is older than or equal to the provided
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* CSN.
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*
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* @param csn
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* The CSN to be compared.
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* @return {@code true} if this CSN is older than or equal to the provided
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* CSN.
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*/
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public boolean isOlderThanOrEqualTo(CSN csn)
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{
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return compare(this, csn) <= 0;
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}
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/**
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* Returns {@code true} if this CSN is newer than or equal to the provided
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* CSN.
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*
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* @param csn
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* The CSN to be compared.
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* @return {@code true} if this CSN is newer than or equal to the provided
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* CSN.
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*/
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public boolean isNewerThanOrEqualTo(CSN csn)
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{
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return compare(this, csn) >= 0;
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}
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/**
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* Returns {@code true} if this CSN is newer than the provided CSN.
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*
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* @param csn
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* The CSN to be compared.
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* @return {@code true} if this CSN is newer than the provided CSN.
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*/
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public boolean isNewerThan(CSN csn)
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{
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return compare(this, csn) > 0;
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}
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/**
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* Compares this CSN with the provided CSN for order and returns a negative
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* number if this CSN is older than {@code csn}, zero if they have the same
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* age, or a positive number if this CSN is newer than {@code csn}.
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*
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* @param csn
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* The CSN to be compared.
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* @return A negative number if this CSN is older than {@code csn}, zero if
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* they have the same age, or a positive number if this CSN is newer
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* than {@code csn}.
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*/
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@Override
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public int compareTo(CSN csn)
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{
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return compare(this, csn);
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}
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}
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