/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
* or http://forgerock.org/license/CDDLv1.0.html.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at legal-notices/CDDLv1_0.txt.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information:
* Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
*
* Copyright 2006-2009 Sun Microsystems, Inc.
* Portions Copyright 2013-2015 ForgeRock AS.
*/
package org.opends.server.replication.common;
import java.io.Serializable;
import java.util.Date;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteSequenceReader;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.ldap.ByteStringBuilder;
/**
* Class used to represent Change Sequence Numbers.
*
* @see <a href="http://tools.ietf.org/html/draft-ietf-ldup-infomod-08"
* >Inspiration for this class comes from LDAPChangeSequenceNumber</a>
*/
public class CSN implements Serializable, Comparable<CSN>
{
/**
* The number of bytes used by the byte string representation of a change
* number.
*
* @see #valueOf(ByteSequence)
* @see #toByteString()
* @see #toByteString(ByteStringBuilder)
*/
public static final int BYTE_ENCODING_LENGTH = 14;
/**
* The number of characters used by the string representation of a change
* number.
*
* @see #valueOf(String)
* @see #toString()
*/
public static final int STRING_ENCODING_LENGTH = 28;
/** The maximum possible value for a CSN. */
public static final CSN MAX_CSN_VALUE = new CSN(Long.MAX_VALUE, Integer.MAX_VALUE, Short.MAX_VALUE);
private static final long serialVersionUID = -8802722277749190740L;
private final long timeStamp;
/**
* The sequence number is set to zero at the start of each millisecond, and
* incremented by one for each update operation that occurs within that
* millisecond. It allows to distinguish changes that have been done in the
* same millisecond.
*/
private final int seqnum;
private final int serverId;
/**
* Parses the provided {@link #toString()} representation of a CSN.
*
* @param s
* The string to be parsed.
* @return The parsed CSN.
* @see #toString()
*/
public static CSN valueOf(String s)
{
return new CSN(s);
}
/**
* Decodes the provided {@link #toByteString()} representation of a change
* number.
*
* @param bs
* The byte sequence to be parsed.
* @return The decoded CSN.
* @see #toByteString()
*/
public static CSN valueOf(ByteSequence bs)
{
ByteSequenceReader reader = bs.asReader();
long timeStamp = reader.readLong();
int serverId = reader.readShort() & 0xffff;
int seqnum = reader.readInt();
return new CSN(timeStamp, seqnum, serverId);
}
/**
* Create a new {@link CSN} from a String.
*
* @param str
* the string from which to create a {@link CSN}
*/
public CSN(String str)
{
String temp = str.substring(0, 16);
timeStamp = Long.parseLong(temp, 16);
temp = str.substring(16, 20);
serverId = Integer.parseInt(temp, 16);
temp = str.substring(20, 28);
seqnum = Integer.parseInt(temp, 16);
}
/**
* Create a new {@link CSN}.
*
* @param timeStamp
* timeStamp for the {@link CSN}
* @param seqNum
* sequence number
* @param serverId
* identity of server
*/
public CSN(long timeStamp, int seqNum, int serverId)
{
this.serverId = serverId;
this.timeStamp = timeStamp;
this.seqnum = seqNum;
}
/**
* Getter for the time.
*
* @return the time
*/
public long getTime()
{
return timeStamp;
}
/**
* Get the timestamp associated to this {@link CSN} in seconds.
*
* @return timestamp associated to this {@link CSN} in seconds
*/
public long getTimeSec()
{
return timeStamp / 1000;
}
/**
* Getter for the sequence number.
*
* @return the sequence number
*/
public int getSeqnum()
{
return seqnum;
}
/**
* Getter for the server ID.
*
* @return the server ID
*/
public int getServerId()
{
return serverId;
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
{
return true;
}
else if (obj instanceof CSN)
{
final CSN csn = (CSN) obj;
return this.seqnum == csn.seqnum && this.serverId == csn.serverId
&& this.timeStamp == csn.timeStamp;
}
else
{
return false;
}
}
@Override
public int hashCode()
{
return this.seqnum + this.serverId + Long.valueOf(timeStamp).hashCode();
}
/**
* Encodes this CSN as a byte string.
* <p>
* NOTE: this representation must not be modified otherwise interop with
* earlier protocol versions will be broken.
*
* @return The encoded representation of this CSN.
* @see #valueOf(ByteSequence)
*/
public ByteString toByteString()
{
final ByteStringBuilder builder = new ByteStringBuilder(BYTE_ENCODING_LENGTH);
toByteString(builder);
return builder.toByteString();
}
/**
* Encodes this CSN into the provided byte string builder.
* <p>
* NOTE: this representation must not be modified otherwise interop with
* earlier protocol versions will be broken.
*
* @param builder
* The byte string builder.
* @see #valueOf(ByteSequence)
*/
public void toByteString(ByteStringBuilder builder)
{
builder.appendLong(timeStamp).appendShort(serverId & 0xffff).appendInt(seqnum);
}
/**
* Convert the {@link CSN} to a printable String.
* <p>
* NOTE: this representation must not be modified otherwise interop with
* earlier protocol versions will be broken.
*
* @return the string
*/
@Override
public String toString()
{
final StringBuilder buffer = new StringBuilder();
toString(buffer);
return buffer.toString();
}
/**
* Appends the text representation of this {@link CSN} into the provided StringBuilder.
* <p>
* NOTE: this representation must not be modified otherwise interop with
* earlier protocol versions will be broken.
*
* @param buffer the StringBuilder where to output the CSN text representation
*/
void toString(final StringBuilder buffer)
{
leftPadWithZeros(buffer, 16, Long.toHexString(timeStamp));
leftPadWithZeros(buffer, 4, Integer.toHexString(serverId));
leftPadWithZeros(buffer, 8, Integer.toHexString(seqnum));
}
private void leftPadWithZeros(StringBuilder buffer, int nbChars, String toAppend)
{
final int padding = nbChars - toAppend.length();
for (int i = 0; i < padding; i++)
{
buffer.append('0');
}
buffer.append(toAppend);
}
/**
* Convert the {@link CSN} to a printable String with a user friendly format.
*
* @return the string
*/
public String toStringUI()
{
final StringBuilder buffer = new StringBuilder();
toStringUI(buffer);
return buffer.toString();
}
private void toStringUI(final StringBuilder buffer)
{
toString(buffer);
buffer.append(" (sid=").append(serverId)
.append(",tsd=").append(new Date(timeStamp))
.append(",ts=").append(timeStamp)
.append(",seqnum=").append(seqnum)
.append(")");
}
/**
* Compares this CSN with the provided CSN for order and returns a negative
* number if {@code csn1} is older than {@code csn2}, zero if they have the
* same age, or a positive number if {@code csn1} is newer than {@code csn2}.
*
* @param csn1
* The first CSN to be compared, which may be {@code null}.
* @param csn2
* The second CSN to be compared, which may be {@code null}.
* @return A negative number if {@code csn1} is older than {@code csn2}, zero
* if they have the same age, or a positive number if {@code csn1} is
* newer than {@code csn2}.
*/
public static int compare(CSN csn1, CSN csn2)
{
if (csn1 == null)
{
return csn2 == null ? 0 : -1;
}
else if (csn2 == null)
{
return 1;
}
else if (csn1.timeStamp != csn2.timeStamp)
{
return csn1.timeStamp < csn2.timeStamp ? -1 : 1;
}
else if (csn1.seqnum != csn2.seqnum)
{
return csn1.seqnum - csn2.seqnum;
}
else
{
return csn1.serverId - csn2.serverId;
}
}
/**
* Computes the difference in number of changes between 2 CSNs. First one is
* expected to be newer than second one. If this is not the case, 0 will be
* returned.
*
* @param csn1
* the first {@link CSN}
* @param csn2
* the second {@link CSN}
* @return the difference
*/
public static int diffSeqNum(CSN csn1, CSN csn2)
{
if (csn1 == null)
{
return 0;
}
if (csn2 == null)
{
return csn1.getSeqnum();
}
if (csn2.isNewerThanOrEqualTo(csn1))
{
return 0;
}
int seqnum1 = csn1.getSeqnum();
long time1 = csn1.getTime();
int seqnum2 = csn2.getSeqnum();
long time2 = csn2.getTime();
if (time2 <= time1)
{
if (seqnum2 <= seqnum1)
{
return seqnum1 - seqnum2;
}
return Integer.MAX_VALUE - (seqnum2 - seqnum1) + 1;
}
return 0;
}
/**
* Returns {@code true} if this CSN is older than the provided CSN.
*
* @param csn
* The CSN to be compared.
* @return {@code true} if this CSN is older than the provided CSN.
*/
public boolean isOlderThan(CSN csn)
{
return compare(this, csn) < 0;
}
/**
* Returns {@code true} if this CSN is older than or equal to the provided
* CSN.
*
* @param csn
* The CSN to be compared.
* @return {@code true} if this CSN is older than or equal to the provided
* CSN.
*/
public boolean isOlderThanOrEqualTo(CSN csn)
{
return compare(this, csn) <= 0;
}
/**
* Returns {@code true} if this CSN is newer than or equal to the provided
* CSN.
*
* @param csn
* The CSN to be compared.
* @return {@code true} if this CSN is newer than or equal to the provided
* CSN.
*/
public boolean isNewerThanOrEqualTo(CSN csn)
{
return compare(this, csn) >= 0;
}
/**
* Returns {@code true} if this CSN is newer than the provided CSN.
*
* @param csn
* The CSN to be compared.
* @return {@code true} if this CSN is newer than the provided CSN.
*/
public boolean isNewerThan(CSN csn)
{
return compare(this, csn) > 0;
}
/**
* Compares this CSN with the provided CSN for order and returns a negative
* number if this CSN is older than {@code csn}, zero if they have the same
* age, or a positive number if this CSN is newer than {@code csn}.
*
* @param csn
* The CSN to be compared.
* @return A negative number if this CSN is older than {@code csn}, zero if
* they have the same age, or a positive number if this CSN is newer
* than {@code csn}.
*/
@Override
public int compareTo(CSN csn)
{
return compare(this, csn);
}
}