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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.allocator;
import org.elasticsearch.cluster.routing.allocation.FailedRerouteAllocation;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.routing.allocation.StartedRerouteAllocation;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.gateway.GatewayAllocator;
/**
* The {@link ShardsAllocator} class offers methods for allocating shard within a cluster.
* These methods include moving shards and re-balancing the cluster. It also allows management
* of shards by their state.
*/
public class ShardsAllocators extends AbstractComponent implements ShardsAllocator {
private final GatewayAllocator gatewayAllocator;
private final ShardsAllocator allocator;
public ShardsAllocators(GatewayAllocator allocator) {
this(Settings.Builder.EMPTY_SETTINGS, allocator);
}
public ShardsAllocators(Settings settings, GatewayAllocator allocator) {
this(settings, allocator, new BalancedShardsAllocator(settings));
}
@Inject
public ShardsAllocators(Settings settings, GatewayAllocator gatewayAllocator, ShardsAllocator allocator) {
super(settings);
this.gatewayAllocator = gatewayAllocator;
this.allocator = allocator;
}
@Override
public void applyStartedShards(StartedRerouteAllocation allocation) {
gatewayAllocator.applyStartedShards(allocation);
allocator.applyStartedShards(allocation);
}
@Override
public void applyFailedShards(FailedRerouteAllocation allocation) {
gatewayAllocator.applyFailedShards(allocation);
allocator.applyFailedShards(allocation);
}
@Override
public boolean allocateUnassigned(RoutingAllocation allocation) {
boolean changed = false;
changed |= gatewayAllocator.allocateUnassigned(allocation);
changed |= allocator.allocateUnassigned(allocation);
return changed;
}
protected long nanoTime() {
return System.nanoTime();
}
@Override
public boolean rebalance(RoutingAllocation allocation) {
if (allocation.hasPendingAsyncFetch() == false) {
/*
* see https://github.com/elastic/elasticsearch/issues/14387
* if we allow rebalance operations while we are still fetching shard store data
* we might end up with unnecessary rebalance operations which can be super confusion/frustrating
* since once the fetches come back we might just move all the shards back again.
* Therefore we only do a rebalance if we have fetched all information.
*/
return allocator.rebalance(allocation);
} else {
logger.debug("skipping rebalance due to in-flight shard/store fetches");
return false;
}
}
@Override
public boolean moveShards(RoutingAllocation allocation) {
return allocator.moveShards(allocation);
}
}