org.jivesoftware.smack.sm.SMUtils Maven / Gradle / Ivy
/**
*
* Copyright © 2014 Florian Schmaus
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jivesoftware.smack.sm;
import java.math.BigInteger;
public class SMUtils {
private static long MASK_32_BIT = BigInteger.ONE.shiftLeft(32).subtract(BigInteger.ONE).longValue();
/**
* Increment the Stream Management height counter.
*
* Quoting XEP-198 4.:
* "In the unlikely case that the number of stanzas handled during a stream management session exceeds the number
* of digits that can be represented by the unsignedInt datatype as specified in XML Schema Part 2 [10]
* (i.e., 2^32), the value of 'h' SHALL be reset from 2^32-1 back to zero (rather than being incremented to 2^32)."
*
* @param height TODO javadoc me please
* @return the incremented height
*/
public static long incrementHeight(long height) {
return ++height & MASK_32_BIT;
}
/**
* Calculates the delta of the last known stanza handled count and the new
* reported stanza handled count while considering that the new value may be
* wrapped after 2^32-1.
*
* @param reportedHandledCount TODO javadoc me please
* @param lastKnownHandledCount TODO javadoc me please
* @return the delta
*/
public static long calculateDelta(long reportedHandledCount, long lastKnownHandledCount) {
if (lastKnownHandledCount > reportedHandledCount) {
throw new IllegalStateException("Illegal Stream Management State: Last known handled count (" + lastKnownHandledCount + ") is greater than reported handled count (" + reportedHandledCount + ')');
}
return (reportedHandledCount - lastKnownHandledCount) & MASK_32_BIT;
}
}