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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.routing;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.UUIDs;
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.ObjectParser;
import org.elasticsearch.common.xcontent.ToXContent;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import java.io.IOException;
import java.util.Objects;
/**
* Uniquely identifies an allocation. An allocation is a shard moving from unassigned to initializing,
* or relocation.
* <p>
* Relocation is a special case, where the origin shard is relocating with a relocationId and same id, and
* the target shard (only materialized in RoutingNodes) is initializing with the id set to the origin shard
* relocationId. Once relocation is done, the new allocation id is set to the relocationId. This is similar
* behavior to how ShardRouting#currentNodeId is used.
*/
public class AllocationId implements ToXContent, Writeable {
private static final String ID_KEY = "id";
private static final String RELOCATION_ID_KEY = "relocation_id";
private static final ObjectParser<AllocationId.Builder, Void> ALLOCATION_ID_PARSER = new ObjectParser<>(
"allocationId");
static {
ALLOCATION_ID_PARSER.declareString(AllocationId.Builder::setId, new ParseField(ID_KEY));
ALLOCATION_ID_PARSER.declareString(AllocationId.Builder::setRelocationId, new ParseField(RELOCATION_ID_KEY));
}
private static class Builder {
private String id;
private String relocationId;
public void setId(String id) {
this.id = id;
}
public void setRelocationId(String relocationId) {
this.relocationId = relocationId;
}
public AllocationId build() {
return new AllocationId(id, relocationId);
}
}
private final String id;
@Nullable
private final String relocationId;
AllocationId(StreamInput in) throws IOException {
this.id = in.readString();
this.relocationId = in.readOptionalString();
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeString(this.id);
out.writeOptionalString(this.relocationId);
}
private AllocationId(String id, String relocationId) {
Objects.requireNonNull(id, "Argument [id] must be non-null");
this.id = id;
this.relocationId = relocationId;
}
/**
* Creates a new allocation id for initializing allocation.
*/
public static AllocationId newInitializing() {
return new AllocationId(UUIDs.randomBase64UUID(), null);
}
/**
* Creates a new allocation id for initializing allocation based on an existing id.
*/
public static AllocationId newInitializing(String existingAllocationId) {
return new AllocationId(existingAllocationId, null);
}
/**
* Creates a new allocation id for the target initializing shard that is the result
* of a relocation.
*/
public static AllocationId newTargetRelocation(AllocationId allocationId) {
assert allocationId.getRelocationId() != null;
return new AllocationId(allocationId.getRelocationId(), allocationId.getId());
}
/**
* Creates a new allocation id for a shard that moves to be relocated, populating
* the transient holder for relocationId.
*/
public static AllocationId newRelocation(AllocationId allocationId) {
assert allocationId.getRelocationId() == null;
return new AllocationId(allocationId.getId(), UUIDs.randomBase64UUID());
}
/**
* Creates a new allocation id representing a cancelled relocation.
* <p>
* Note that this is expected to be called on the allocation id
* of the *source* shard
*/
public static AllocationId cancelRelocation(AllocationId allocationId) {
assert allocationId.getRelocationId() != null;
return new AllocationId(allocationId.getId(), null);
}
/**
* Creates a new allocation id finalizing a relocation.
* <p>
* Note that this is expected to be called on the allocation id
* of the *target* shard and thus it only needs to clear the relocating id.
*/
public static AllocationId finishRelocation(AllocationId allocationId) {
assert allocationId.getRelocationId() != null;
return new AllocationId(allocationId.getId(), null);
}
/**
* The allocation id uniquely identifying an allocation, note, if it is relocation
* the {@link #getRelocationId()} need to be taken into account as well.
*/
public String getId() {
return id;
}
/**
* The transient relocation id holding the unique id that is used for relocation.
*/
public String getRelocationId() {
return relocationId;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null) {
return false;
}
AllocationId that = (AllocationId) o;
if (!id.equals(that.id)) {
return false;
}
return !(relocationId != null ? !relocationId.equals(that.relocationId) : that.relocationId != null);
}
@Override
public int hashCode() {
int result = id.hashCode();
result = 31 * result + (relocationId != null ? relocationId.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "[id=" + id + (relocationId == null ? "" : ", rId=" + relocationId) + "]";
}
@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
builder.startObject();
builder.field(ID_KEY, id);
if (relocationId != null) {
builder.field(RELOCATION_ID_KEY, relocationId);
}
builder.endObject();
return builder;
}
public static AllocationId fromXContent(XContentParser parser) throws IOException {
return ALLOCATION_ID_PARSER.parse(parser, new AllocationId.Builder(), null).build();
}
}