com.couchbase.client.core.deps.org.xbill.DNS.Serial Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of core-io Show documentation
Show all versions of core-io Show documentation
The official Couchbase JVM Core IO Library
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 2003-2004 Brian Wellington ([email protected])
package com.couchbase.client.core.deps.org.xbill.DNS;
/**
* Helper functions for doing serial arithmetic. These should be used when setting/checking SOA
* serial numbers. SOA serial number arithmetic is defined in RFC 1982 and also referenced in RFC
* 2136.
*
* @author Brian Wellington
*/
public final class Serial {
private static final long MAX32 = 0xFFFFFFFFL;
private Serial() {}
/**
* Compares two numbers using serial arithmetic. The numbers are assumed to be 32 bit unsigned
* integers stored in longs.
*
* @param serial1 The first integer
* @param serial2 The second integer
* @return 0 if the 2 numbers are equal, a positive number if serial1 is greater than serial2, and
* a negative number if serial2 is greater than serial1.
* @throws IllegalArgumentException serial1 or serial2 is out of range
*/
public static int compare(long serial1, long serial2) {
if (serial1 < 0 || serial1 > MAX32) {
throw new IllegalArgumentException(serial1 + " out of range");
}
if (serial2 < 0 || serial2 > MAX32) {
throw new IllegalArgumentException(serial2 + " out of range");
}
long diff = serial1 - serial2;
if (diff >= MAX32) {
diff -= MAX32 + 1;
} else if (diff < -MAX32) {
diff += MAX32 + 1;
}
return (int) diff;
}
/**
* Increments a serial number. The number is assumed to be a 32 bit unsigned integer stored in a
* long. This basically adds 1 and resets the value to 1 if it is 2^32. A zero value is explicitly
* forbidden as per * RFC 2136 section 4.2 and 7.11.
*
* @param serial The serial number
* @return The incremented serial number
* @throws IllegalArgumentException serial is out of range
*/
public static long increment(long serial) {
if (serial < 0 || serial > MAX32) {
throw new IllegalArgumentException(serial + " out of range");
}
if (serial == MAX32) {
return 1;
}
return serial + 1;
}
}