io.debezium.connector.sqlserver.Lsn Maven / Gradle / Ivy
/*
* Copyright Debezium Authors.
*
* Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
*/
package io.debezium.connector.sqlserver;
import java.util.Arrays;
import io.debezium.connector.Nullable;
import io.debezium.util.Strings;
/**
* A logical representation of SQL Server LSN (log sequence number) position. When LSN is not available
* it is replaced with {@link Lsn#NULL} constant.
*
* @author Jiri Pechanec
*
*/
public class Lsn implements Comparable, Nullable {
private static final String NULL_STRING = "NULL";
public static final Lsn NULL = new Lsn(null);
private final byte[] binary;
private int[] unsignedBinary;
private String string;
private Lsn(byte[] binary) {
this.binary = binary;
}
/**
* @return binary representation of the stored LSN
*/
public byte[] getBinary() {
return binary;
}
/**
* @return true if this is a real LSN or false it it is {@code NULL}
*/
@Override
public boolean isAvailable() {
return binary != null;
}
private int[] getUnsignedBinary() {
if (unsignedBinary != null || binary == null) {
return unsignedBinary;
}
unsignedBinary = new int[binary.length];
for (int i = 0; i < binary.length; i++) {
unsignedBinary[i] = Byte.toUnsignedInt(binary[i]);
}
return unsignedBinary;
}
/**
* @return textual representation of the stored LSN
*/
public String toString() {
if (string != null) {
return string;
}
final StringBuilder sb = new StringBuilder();
if (binary == null) {
return NULL_STRING;
}
final int[] unsigned = getUnsignedBinary();
for (int i = 0; i < unsigned.length; i++) {
final String byteStr = Integer.toHexString(unsigned[i]);
if (byteStr.length() == 1) {
sb.append('0');
}
sb.append(byteStr);
if (i == 3 || i == 7) {
sb.append(':');
}
}
string = sb.toString();
return string;
}
/**
* @param lsnString - textual representation of Lsn
* @return LSN converted from its textual representation
*/
public static Lsn valueOf(String lsnString) {
return (lsnString == null || NULL_STRING.equals(lsnString)) ? NULL : new Lsn(Strings.hexStringToByteArray(lsnString.replace(":", "")));
}
/**
* @param lsnBinary - binary representation of Lsn
* @return LSN converted from its binary representation
*/
public static Lsn valueOf(byte[] lsnBinary) {
return (lsnBinary == null) ? NULL : new Lsn(lsnBinary);
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + Arrays.hashCode(binary);
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
Lsn other = (Lsn) obj;
if (!Arrays.equals(binary, other.binary)) {
return false;
}
return true;
}
/**
* Enables ordering of LSNs. The {@code NULL} LSN is always the smallest one.
*/
@Override
public int compareTo(Lsn o) {
if (this == o) {
return 0;
}
if (!this.isAvailable()) {
if (!o.isAvailable()) {
return 0;
}
return -1;
}
if (!o.isAvailable()) {
return 1;
}
final int[] thisU = getUnsignedBinary();
final int[] thatU = o.getUnsignedBinary();
for (int i = 0; i < thisU.length; i++) {
final int diff = thisU[i] - thatU[i];
if (diff != 0) {
return diff;
}
}
return 0;
}
/**
* Verifies whether the LSN falls into a LSN interval
*
* @param from start of the interval (included)
* @param to end of the interval (excluded)
*
* @return true if the LSN falls into the interval
*/
public boolean isBetween(Lsn from, Lsn to) {
return this.compareTo(from) >= 0 && this.compareTo(to) < 0;
}
}