/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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.elasticsearch.index.seqno;
import java.util.Map;
/**
* A utility class for handling sequence numbers.
*/
public class SequenceNumbers {
public static final String LOCAL_CHECKPOINT_KEY = "local_checkpoint";
public static final String MAX_SEQ_NO = "max_seq_no";
/**
* Reads the sequence number stats from the commit data (maximum sequence number and local checkpoint) and uses the specified global
* checkpoint.
*
* @param globalCheckpoint the global checkpoint to use
* @param commitData the commit data
* @return the sequence number stats
*/
public static SeqNoStats loadSeqNoStatsFromLuceneCommit(
final long globalCheckpoint,
final Iterable<Map.Entry<String, String>> commitData) {
long maxSeqNo = SequenceNumbersService.NO_OPS_PERFORMED;
long localCheckpoint = SequenceNumbersService.NO_OPS_PERFORMED;
for (final Map.Entry<String, String> entry : commitData) {
final String key = entry.getKey();
if (key.equals(SequenceNumbers.LOCAL_CHECKPOINT_KEY)) {
assert localCheckpoint == SequenceNumbersService.NO_OPS_PERFORMED : localCheckpoint;
localCheckpoint = Long.parseLong(entry.getValue());
} else if (key.equals(SequenceNumbers.MAX_SEQ_NO)) {
assert maxSeqNo == SequenceNumbersService.NO_OPS_PERFORMED : maxSeqNo;
maxSeqNo = Long.parseLong(entry.getValue());
}
}
return new SeqNoStats(maxSeqNo, localCheckpoint, globalCheckpoint);
}
/**
* Compute the minimum of the given current minimum sequence number and the specified sequence number, accounting for the fact that the
* current minimum sequence number could be {@link SequenceNumbersService#NO_OPS_PERFORMED} or
* {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}. When the current minimum sequence number is not
* {@link SequenceNumbersService#NO_OPS_PERFORMED} nor {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}, the specified sequence number
* must not be {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}.
*
* @param minSeqNo the current minimum sequence number
* @param seqNo the specified sequence number
* @return the new minimum sequence number
*/
public static long min(final long minSeqNo, final long seqNo) {
if (minSeqNo == SequenceNumbersService.NO_OPS_PERFORMED) {
return seqNo;
} else if (minSeqNo == SequenceNumbersService.UNASSIGNED_SEQ_NO) {
return seqNo;
} else {
if (seqNo == SequenceNumbersService.UNASSIGNED_SEQ_NO) {
throw new IllegalArgumentException("sequence number must be assigned");
}
return Math.min(minSeqNo, seqNo);
}
}
/**
* Compute the maximum of the given current maximum sequence number and the specified sequence number, accounting for the fact that the
* current maximum sequence number could be {@link SequenceNumbersService#NO_OPS_PERFORMED} or
* {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}. When the current maximum sequence number is not
* {@link SequenceNumbersService#NO_OPS_PERFORMED} nor {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}, the specified sequence number
* must not be {@link SequenceNumbersService#UNASSIGNED_SEQ_NO}.
*
* @param maxSeqNo the current maximum sequence number
* @param seqNo the specified sequence number
* @return the new maximum sequence number
*/
public static long max(final long maxSeqNo, final long seqNo) {
if (maxSeqNo == SequenceNumbersService.NO_OPS_PERFORMED) {
return seqNo;
} else if (maxSeqNo == SequenceNumbersService.UNASSIGNED_SEQ_NO) {
return seqNo;
} else {
if (seqNo == SequenceNumbersService.UNASSIGNED_SEQ_NO) {
throw new IllegalArgumentException("sequence number must be assigned");
}
return Math.max(maxSeqNo, seqNo);
}
}
}