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