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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.index.seqno;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.common.xcontent.ConstructingObjectParser;
import org.elasticsearch.common.xcontent.ToXContent;
import org.elasticsearch.common.xcontent.ToXContentFragment;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.gateway.MetaDataStateFormat;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Collectors;
/**
* Represents a versioned collection of retention leases. We version the collection of retention leases to ensure that sync requests that
* arrive out of order on the replica, using the version to ensure that older sync requests are rejected.
*/
public class RetentionLeases implements ToXContentFragment, Writeable {
private final long primaryTerm;
/**
* The primary term of this retention lease collection.
*
* @return the primary term
*/
public long primaryTerm() {
return primaryTerm;
}
private final long version;
/**
* The version of this retention lease collection. The version is managed on the primary and incremented any time that a retention lease
* is added, renewed, or when retention leases expire.
*
* @return the version of this retention lease collection
*/
public long version() {
return version;
}
/**
* Checks if this retention leases collection supersedes the specified retention leases collection. A retention leases collection
* supersedes another retention leases collection if its primary term is higher, or if for equal primary terms its version is higher.
*
* @param that the retention leases collection to test against
* @return true if this retention leases collection supercedes the specified retention lease collection, otherwise false
*/
boolean supersedes(final RetentionLeases that) {
return supersedes(that.primaryTerm, that.version);
}
/**
* Checks if this retention leases collection would supersede a retention leases collection with the specified primary term and version.
* A retention leases collection supersedes another retention leases collection if its primary term is higher, or if for equal primary
* terms its version is higher.
*
* @param primaryTerm the primary term
* @param version the version
* @return true if this retention leases collection would supercedes a retention lease collection with the specified primary term and
* version
*/
boolean supersedes(final long primaryTerm, final long version) {
return this.primaryTerm > primaryTerm || this.primaryTerm == primaryTerm && this.version > version;
}
private final Map leases;
/**
* The underlying collection of retention leases
*
* @return the retention leases
*/
public Collection leases() {
return Collections.unmodifiableCollection(leases.values());
}
/**
* Checks if this retention lease collection contains a retention lease with the specified {@link RetentionLease#id()}.
*
* @param id the retention lease ID
* @return true if this retention lease collection contains a retention lease with the specified ID, otherwise false
*/
public boolean contains(final String id) {
return leases.containsKey(id);
}
/**
* Returns the retention lease with the specified ID, or null if no such retention lease exists.
*
* @param id the retention lease ID
* @return the retention lease, or null if no retention lease with the specified ID exists
*/
public RetentionLease get(final String id) {
return leases.get(id);
}
/**
* Represents an empty an un-versioned retention lease collection. This is used when no retention lease collection is found in the
* commit point
*/
public static RetentionLeases EMPTY = new RetentionLeases(1, 0, Collections.emptyList());
/**
* Constructs a new retention lease collection with the specified version and underlying collection of retention leases.
*
* @param primaryTerm the primary term under which this retention lease collection was created
* @param version the version of this retention lease collection
* @param leases the retention leases
*/
public RetentionLeases(final long primaryTerm, final long version, final Collection leases) {
if (primaryTerm <= 0) {
throw new IllegalArgumentException("primary term must be positive but was [" + primaryTerm + "]");
}
if (version < 0) {
throw new IllegalArgumentException("version must be non-negative but was [" + version + "]");
}
Objects.requireNonNull(leases);
this.primaryTerm = primaryTerm;
this.version = version;
this.leases = Collections.unmodifiableMap(toMap(leases));
}
/**
* Constructs a new retention lease collection from a stream. The retention lease collection should have been written via
* {@link #writeTo(StreamOutput)}.
*
* @param in the stream to construct the retention lease collection from
* @throws IOException if an I/O exception occurs reading from the stream
*/
public RetentionLeases(final StreamInput in) throws IOException {
primaryTerm = in.readVLong();
version = in.readVLong();
leases = Collections.unmodifiableMap(toMap(in.readList(RetentionLease::new)));
}
/**
* Writes a retention lease collection to a stream in a manner suitable for later reconstruction via
* {@link #RetentionLeases(StreamInput)} (StreamInput)}.
*
* @param out the stream to write the retention lease collection to
* @throws IOException if an I/O exception occurs writing to the stream
*/
@Override
public void writeTo(final StreamOutput out) throws IOException {
out.writeVLong(primaryTerm);
out.writeVLong(version);
out.writeCollection(leases.values());
}
private static final ParseField PRIMARY_TERM_FIELD = new ParseField("primary_term");
private static final ParseField VERSION_FIELD = new ParseField("version");
private static final ParseField LEASES_FIELD = new ParseField("leases");
@SuppressWarnings("unchecked")
private static final ConstructingObjectParser PARSER = new ConstructingObjectParser<>(
"retention_leases",
(a) -> new RetentionLeases((Long) a[0], (Long) a[1], (Collection) a[2]));
static {
PARSER.declareLong(ConstructingObjectParser.constructorArg(), PRIMARY_TERM_FIELD);
PARSER.declareLong(ConstructingObjectParser.constructorArg(), VERSION_FIELD);
PARSER.declareObjectArray(ConstructingObjectParser.constructorArg(), (p, c) -> RetentionLease.fromXContent(p), LEASES_FIELD);
}
@Override
public XContentBuilder toXContent(final XContentBuilder builder, final Params params) throws IOException {
builder.field(PRIMARY_TERM_FIELD.getPreferredName(), primaryTerm);
builder.field(VERSION_FIELD.getPreferredName(), version);
builder.startArray(LEASES_FIELD.getPreferredName());
{
for (final RetentionLease retentionLease : leases.values()) {
retentionLease.toXContent(builder, params);
}
}
builder.endArray();
return builder;
}
/**
* Parses a retention leases collection from {@link org.elasticsearch.common.xcontent.XContent}. This method assumes that the retention
* leases were converted to {@link org.elasticsearch.common.xcontent.XContent} via {@link #toXContent(XContentBuilder, Params)}.
*
* @param parser the parser
* @return a retention leases collection
*/
public static RetentionLeases fromXContent(final XContentParser parser) {
return PARSER.apply(parser, null);
}
static final MetaDataStateFormat FORMAT = new MetaDataStateFormat("retention-leases-") {
@Override
public void toXContent(final XContentBuilder builder, final RetentionLeases retentionLeases) throws IOException {
retentionLeases.toXContent(builder, ToXContent.EMPTY_PARAMS);
}
@Override
public RetentionLeases fromXContent(final XContentParser parser) {
return RetentionLeases.fromXContent(parser);
}
};
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
final RetentionLeases that = (RetentionLeases) o;
return primaryTerm == that.primaryTerm &&
version == that.version &&
Objects.equals(leases, that.leases);
}
@Override
public int hashCode() {
return Objects.hash(primaryTerm, version, leases);
}
@Override
public String toString() {
return "RetentionLeases{" +
"primaryTerm=" + primaryTerm +
", version=" + version +
", leases=" + leases +
'}';
}
/**
* A utility method to convert retention leases to a map from retention lease ID to retention lease.
*
* @param leases the retention leases
* @return the map from retention lease ID to retention lease
*/
private static Map toMap(final Collection leases) {
// use a linked hash map to preserve order
return leases.stream()
.collect(Collectors.toMap(
RetentionLease::id,
Function.identity(),
(left, right) -> {
assert left.id().equals(right.id()) : "expected [" + left.id() + "] to equal [" + right.id() + "]";
throw new IllegalStateException("duplicate retention lease ID [" + left.id() + "]");
},
LinkedHashMap::new));
}
}