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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.allocation.decider;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.ToXContent;
import org.elasticsearch.common.xcontent.XContentBuilder;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
/**
* This abstract class defining basic {@link Decision} used during shard
* allocation process.
*
* @see AllocationDecider
*/
public abstract class Decision implements ToXContent {
public static final Decision ALWAYS = new Single(Type.YES);
public static final Decision YES = new Single(Type.YES);
public static final Decision NO = new Single(Type.NO);
public static final Decision THROTTLE = new Single(Type.THROTTLE);
/**
* Creates a simple decision
* @param type {@link Type} of the decision
* @param label label for the Decider that produced this decision
* @param explanation explanation of the decision
* @param explanationParams additional parameters for the decision
* @return new {@link Decision} instance
*/
public static Decision single(Type type, String label, String explanation, Object... explanationParams) {
return new Single(type, label, explanation, explanationParams);
}
public static void writeTo(Decision decision, StreamOutput out) throws IOException {
if (decision instanceof Multi) {
// Flag specifying whether it is a Multi or Single Decision
out.writeBoolean(true);
out.writeVInt(((Multi) decision).decisions.size());
for (Decision d : ((Multi) decision).decisions) {
writeTo(d, out);
}
} else {
// Flag specifying whether it is a Multi or Single Decision
out.writeBoolean(false);
Single d = ((Single) decision);
Type.writeTo(d.type, out);
out.writeOptionalString(d.label);
// Flatten explanation on serialization, so that explanationParams
// do not need to be serialized
out.writeOptionalString(d.getExplanation());
}
}
public static Decision readFrom(StreamInput in) throws IOException {
// Determine whether to read a Single or Multi Decision
if (in.readBoolean()) {
Multi result = new Multi();
int decisionCount = in.readVInt();
for (int i = 0; i < decisionCount; i++) {
Decision s = readFrom(in);
result.decisions.add(s);
}
return result;
} else {
Single result = new Single();
result.type = Type.readFrom(in);
result.label = in.readOptionalString();
result.explanationString = in.readOptionalString();
return result;
}
}
/**
* This enumeration defines the
* possible types of decisions
*/
public static enum Type {
YES,
NO,
THROTTLE;
public static Type resolve(String s) {
return Type.valueOf(s.toUpperCase(Locale.ROOT));
}
public static Type readFrom(StreamInput in) throws IOException {
int i = in.readVInt();
switch (i) {
case 0:
return NO;
case 1:
return YES;
case 2:
return THROTTLE;
default:
throw new IllegalArgumentException("No Type for integer [" + i + "]");
}
}
public static void writeTo(Type type, StreamOutput out) throws IOException {
switch (type) {
case NO:
out.writeVInt(0);
break;
case YES:
out.writeVInt(1);
break;
case THROTTLE:
out.writeVInt(2);
break;
default:
throw new IllegalArgumentException("Invalid Type [" + type + "]");
}
}
}
/**
* Get the {@link Type} of this decision
* @return {@link Type} of this decision
*/
public abstract Type type();
public abstract String label();
/**
* Simple class representing a single decision
*/
public static class Single extends Decision {
private Type type;
private String label;
private String explanation;
private String explanationString;
private Object[] explanationParams;
public Single() {
}
/**
* Creates a new {@link Single} decision of a given type
* @param type {@link Type} of the decision
*/
public Single(Type type) {
this(type, null, null, (Object[]) null);
}
/**
* Creates a new {@link Single} decision of a given type
*
* @param type {@link Type} of the decision
* @param explanation An explanation of this {@link Decision}
* @param explanationParams A set of additional parameters
*/
public Single(Type type, String label, String explanation, Object... explanationParams) {
this.type = type;
this.label = label;
this.explanation = explanation;
this.explanationParams = explanationParams;
}
@Override
public Type type() {
return this.type;
}
@Override
public String label() {
return this.label;
}
/**
* Returns the explanation string, fully formatted. Only formats the string once
*/
public String getExplanation() {
if (explanationString == null && explanation != null) {
explanationString = String.format(Locale.ROOT, explanation, explanationParams);
}
return this.explanationString;
}
@Override
public String toString() {
if (explanation == null) {
return type + "()";
}
return type + "(" + getExplanation() + ")";
}
@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
builder.startObject();
builder.field("decider", label);
builder.field("decision", type);
String explanation = getExplanation();
builder.field("explanation", explanation != null ? explanation : "none");
builder.endObject();
return builder;
}
}
/**
* Simple class representing a list of decisions
*/
public static class Multi extends Decision {
private final List<Decision> decisions = new ArrayList<>();
/**
* Add a decision to this {@link Multi}decision instance
* @param decision {@link Decision} to add
* @return {@link Multi}decision instance with the given decision added
*/
public Multi add(Decision decision) {
decisions.add(decision);
return this;
}
@Override
public Type type() {
Type ret = Type.YES;
for (int i = 0; i < decisions.size(); i++) {
Type type = decisions.get(i).type();
if (type == Type.NO) {
return type;
} else if (type == Type.THROTTLE) {
ret = type;
}
}
return ret;
}
@Override
public String label() {
// Multi decisions have no labels
return null;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (Decision decision : decisions) {
sb.append("[").append(decision.toString()).append("]");
}
return sb.toString();
}
@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
builder.startArray("decisions");
for (Decision d : decisions) {
d.toXContent(builder, params);
}
builder.endArray();
return builder;
}
}
}