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/*
* 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.cluster.metadata;
import org.apache.lucene.util.SetOnce;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.collect.Tuple;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;
/**
* Encapsulates the {@link IndexMetaData} instances of a concrete index or indices an alias is pointing to.
*/
public interface AliasOrIndex {
/**
* @return whether this an alias or concrete index
*/
boolean isAlias();
/**
* @return All {@link IndexMetaData} of all concrete indices this alias is referring to
* or if this is a concrete index its {@link IndexMetaData}
*/
List getIndices();
/**
* Represents an concrete index and encapsulates its {@link IndexMetaData}
*/
class Index implements AliasOrIndex {
private final IndexMetaData concreteIndex;
public Index(IndexMetaData indexMetaData) {
this.concreteIndex = indexMetaData;
}
@Override
public boolean isAlias() {
return false;
}
@Override
public List getIndices() {
return Collections.singletonList(concreteIndex);
}
}
/**
* Represents an alias and groups all {@link IndexMetaData} instances sharing the same alias name together.
*/
class Alias implements AliasOrIndex {
private final String aliasName;
private final List referenceIndexMetaDatas;
private final SetOnce writeIndex = new SetOnce<>();
public Alias(AliasMetaData aliasMetaData, IndexMetaData indexMetaData) {
this.aliasName = aliasMetaData.getAlias();
this.referenceIndexMetaDatas = new ArrayList<>();
this.referenceIndexMetaDatas.add(indexMetaData);
}
@Override
public boolean isAlias() {
return true;
}
public String getAliasName() {
return aliasName;
}
@Override
public List getIndices() {
return referenceIndexMetaDatas;
}
@Nullable
public IndexMetaData getWriteIndex() {
return writeIndex.get();
}
/**
* Returns the unique alias metadata per concrete index.
*
* (note that although alias can point to the same concrete indices, each alias reference may have its own routing
* and filters)
*/
public Iterable> getConcreteIndexAndAliasMetaDatas() {
return () -> new Iterator>() {
int index = 0;
@Override
public boolean hasNext() {
return index < referenceIndexMetaDatas.size();
}
@Override
public Tuple next() {
IndexMetaData indexMetaData = referenceIndexMetaDatas.get(index++);
return new Tuple<>(indexMetaData.getIndex().getName(), indexMetaData.getAliases().get(aliasName));
}
};
}
public AliasMetaData getFirstAliasMetaData() {
return referenceIndexMetaDatas.get(0).getAliases().get(aliasName);
}
void addIndex(IndexMetaData indexMetaData) {
this.referenceIndexMetaDatas.add(indexMetaData);
}
public void computeAndValidateWriteIndex() {
List writeIndices = referenceIndexMetaDatas.stream()
.filter(idxMeta -> Boolean.TRUE.equals(idxMeta.getAliases().get(aliasName).writeIndex()))
.collect(Collectors.toList());
if (writeIndices.isEmpty() && referenceIndexMetaDatas.size() == 1
&& referenceIndexMetaDatas.get(0).getAliases().get(aliasName).writeIndex() == null) {
writeIndices.add(referenceIndexMetaDatas.get(0));
}
if (writeIndices.size() == 1) {
writeIndex.set(writeIndices.get(0));
} else if (writeIndices.size() > 1) {
List writeIndicesStrings = writeIndices.stream()
.map(i -> i.getIndex().getName()).collect(Collectors.toList());
throw new IllegalStateException("alias [" + aliasName + "] has more than one write index [" +
Strings.collectionToCommaDelimitedString(writeIndicesStrings) + "]");
}
}
}
}