com.datastax.oss.driver.internal.core.loadbalancing.helper.InferringLocalDcHelper Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 com.datastax.oss.driver.internal.core.loadbalancing.helper;
import static com.datastax.oss.driver.internal.core.time.Clock.LOG;
import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
import com.datastax.oss.driver.api.core.metadata.Node;
import com.datastax.oss.driver.internal.core.context.InternalDriverContext;
import com.datastax.oss.driver.internal.core.metadata.DefaultNode;
import edu.umd.cs.findbugs.annotations.NonNull;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.UUID;
import net.jcip.annotations.ThreadSafe;
/**
* An implementation of {@link LocalDcHelper} that fetches the user-supplied datacenter, if any,
* from the programmatic configuration API, or else, from the driver configuration. If no local
* datacenter is explicitly defined, this implementation infers the local datacenter from the
* contact points: if all contact points share the same datacenter, that datacenter is returned. If
* the contact points are from different datacenters, or if no contact points reported any
* datacenter, an {@link IllegalStateException} is thrown.
*/
@ThreadSafe
public class InferringLocalDcHelper extends OptionalLocalDcHelper {
public InferringLocalDcHelper(
@NonNull InternalDriverContext context,
@NonNull DriverExecutionProfile profile,
@NonNull String logPrefix) {
super(context, profile, logPrefix);
}
/** @return The local datacenter; always present. */
@NonNull
@Override
public Optional discoverLocalDc(@NonNull Map nodes) {
Optional optionalLocalDc = super.discoverLocalDc(nodes);
if (optionalLocalDc.isPresent()) {
return optionalLocalDc;
}
Set datacenters = new HashSet<>();
Set contactPoints = context.getMetadataManager().getContactPoints();
for (Node node : contactPoints) {
String datacenter = node.getDatacenter();
if (datacenter != null) {
datacenters.add(datacenter);
}
}
if (datacenters.size() == 1) {
String localDc = datacenters.iterator().next();
LOG.info("[{}] Inferred local DC from contact points: {}", logPrefix, localDc);
return Optional.of(localDc);
}
if (datacenters.isEmpty()) {
throw new IllegalStateException(
"The local DC could not be inferred from contact points, please set it explicitly (see "
+ DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER.getPath()
+ " in the config, or set it programmatically with SessionBuilder.withLocalDatacenter)");
}
throw new IllegalStateException(
String.format(
"No local DC was provided, but the contact points are from different DCs: %s; "
+ "please set the local DC explicitly (see "
+ DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER.getPath()
+ " in the config, or set it programmatically with SessionBuilder.withLocalDatacenter)",
formatNodesAndDcs(contactPoints)));
}
}