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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.cluster.metadata;
import org.elasticsearch.Version;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.routing.allocation.decider.Decision;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.core.Booleans;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.OptionalInt;
import static org.elasticsearch.cluster.metadata.MetadataIndexStateService.isIndexVerifiedBeforeClosed;
/**
* This class acts as a functional wrapper around the {@code index.auto_expand_replicas} setting.
* This setting or rather it's value is expanded into a min and max value which requires special handling
* based on the number of datanodes in the cluster. This class handles all the parsing and streamlines the access to these values.
*/
public final class AutoExpandReplicas {
// the value we recognize in the "max" position to mean all the nodes
private static final String ALL_NODES_VALUE = "all";
private static final AutoExpandReplicas FALSE_INSTANCE = new AutoExpandReplicas(0, 0, false);
public static final Setting SETTING = new Setting<>(
IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS,
"false",
AutoExpandReplicas::parse,
Property.Dynamic,
Property.IndexScope
);
private static AutoExpandReplicas parse(String value) {
final int min;
final int max;
if (Booleans.isFalse(value)) {
return FALSE_INSTANCE;
}
final int dash = value.indexOf('-');
if (-1 == dash) {
throw new IllegalArgumentException(
"failed to parse [" + IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS + "] from value: [" + value + "] at index " + dash
);
}
final String sMin = value.substring(0, dash);
try {
min = Integer.parseInt(sMin);
} catch (NumberFormatException e) {
throw new IllegalArgumentException(
"failed to parse [" + IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS + "] from value: [" + value + "] at index " + dash,
e
);
}
String sMax = value.substring(dash + 1);
if (sMax.equals(ALL_NODES_VALUE)) {
max = Integer.MAX_VALUE;
} else {
try {
max = Integer.parseInt(sMax);
} catch (NumberFormatException e) {
throw new IllegalArgumentException(
"failed to parse [" + IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS + "] from value: [" + value + "] at index " + dash,
e
);
}
}
return new AutoExpandReplicas(min, max, true);
}
private final int minReplicas;
private final int maxReplicas;
private final boolean enabled;
private AutoExpandReplicas(int minReplicas, int maxReplicas, boolean enabled) {
if (minReplicas > maxReplicas) {
throw new IllegalArgumentException(
"["
+ IndexMetadata.SETTING_AUTO_EXPAND_REPLICAS
+ "] minReplicas must be =< maxReplicas but wasn't "
+ minReplicas
+ " > "
+ maxReplicas
);
}
this.minReplicas = minReplicas;
this.maxReplicas = maxReplicas;
this.enabled = enabled;
}
int getMinReplicas() {
return minReplicas;
}
int getMaxReplicas(int numDataNodes) {
return Math.min(maxReplicas, numDataNodes - 1);
}
public boolean expandToAllNodes() {
return maxReplicas == Integer.MAX_VALUE;
}
private OptionalInt getDesiredNumberOfReplicas(IndexMetadata indexMetadata, RoutingAllocation allocation) {
if (enabled) {
int numMatchingDataNodes = 0;
// Only start using new logic once all nodes are migrated to 7.6.0, avoiding disruption during an upgrade
if (allocation.nodes().getMinNodeVersion().onOrAfter(Version.V_7_6_0)) {
for (DiscoveryNode discoveryNode : allocation.nodes().getDataNodes().values()) {
Decision decision = allocation.deciders().shouldAutoExpandToNode(indexMetadata, discoveryNode, allocation);
if (decision.type() != Decision.Type.NO) {
numMatchingDataNodes++;
}
}
} else {
numMatchingDataNodes = allocation.nodes().getDataNodes().size();
}
final int min = getMinReplicas();
final int max = getMaxReplicas(numMatchingDataNodes);
int numberOfReplicas = numMatchingDataNodes - 1;
if (numberOfReplicas < min) {
numberOfReplicas = min;
} else if (numberOfReplicas > max) {
numberOfReplicas = max;
}
if (numberOfReplicas >= min && numberOfReplicas <= max) {
return OptionalInt.of(numberOfReplicas);
}
}
return OptionalInt.empty();
}
@Override
public String toString() {
return enabled ? minReplicas + "-" + maxReplicas : "false";
}
/**
* Checks if there are replicas with the auto-expand feature that need to be adapted.
* Returns a map of updates, which maps the indices to be updated to the desired number of replicas.
* The map has the desired number of replicas as key and the indices to update as value, as this allows the result
* of this method to be directly applied to RoutingTable.Builder#updateNumberOfReplicas.
*/
public static Map> getAutoExpandReplicaChanges(Metadata metadata, RoutingAllocation allocation) {
Map> nrReplicasChanged = new HashMap<>();
for (final IndexMetadata indexMetadata : metadata) {
if (indexMetadata.getState() == IndexMetadata.State.OPEN || isIndexVerifiedBeforeClosed(indexMetadata)) {
AutoExpandReplicas autoExpandReplicas = SETTING.get(indexMetadata.getSettings());
autoExpandReplicas.getDesiredNumberOfReplicas(indexMetadata, allocation).ifPresent(numberOfReplicas -> {
if (numberOfReplicas != indexMetadata.getNumberOfReplicas()) {
nrReplicasChanged.computeIfAbsent(numberOfReplicas, ArrayList::new).add(indexMetadata.getIndex().getName());
}
});
}
}
return nrReplicasChanged;
}
}