/**
* 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 org.apache.hadoop.yarn.util;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
import org.apache.hadoop.net.CachedDNSToSwitchMapping;
import org.apache.hadoop.net.DNSToSwitchMapping;
import org.apache.hadoop.net.NetworkTopology;
import org.apache.hadoop.net.Node;
import org.apache.hadoop.net.NodeBase;
import org.apache.hadoop.net.ScriptBasedMapping;
import org.apache.hadoop.util.ReflectionUtils;
import com.google.common.annotations.VisibleForTesting;
@InterfaceAudience.LimitedPrivate({"YARN", "MAPREDUCE"})
public class RackResolver {
private static DNSToSwitchMapping dnsToSwitchMapping;
private static boolean initCalled = false;
private static final Log LOG = LogFactory.getLog(RackResolver.class);
public synchronized static void init(Configuration conf) {
if (initCalled) {
return;
} else {
initCalled = true;
}
Class<? extends DNSToSwitchMapping> dnsToSwitchMappingClass =
conf.getClass(
CommonConfigurationKeysPublic.NET_TOPOLOGY_NODE_SWITCH_MAPPING_IMPL_KEY,
ScriptBasedMapping.class,
DNSToSwitchMapping.class);
try {
DNSToSwitchMapping newInstance = ReflectionUtils.newInstance(
dnsToSwitchMappingClass, conf);
// Wrap around the configured class with the Cached implementation so as
// to save on repetitive lookups.
// Check if the impl is already caching, to avoid double caching.
dnsToSwitchMapping =
((newInstance instanceof CachedDNSToSwitchMapping) ? newInstance
: new CachedDNSToSwitchMapping(newInstance));
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/**
* Utility method for getting a hostname resolved to a node in the
* network topology. This method initializes the class with the
* right resolver implementation.
* @param conf
* @param hostName
* @return node {@link Node} after resolving the hostname
*/
public static Node resolve(Configuration conf, String hostName) {
init(conf);
return coreResolve(hostName);
}
/**
* Utility method for getting a hostname resolved to a node in the
* network topology. This method doesn't initialize the class.
* Call {@link #init(Configuration)} explicitly.
* @param hostName
* @return node {@link Node} after resolving the hostname
*/
public static Node resolve(String hostName) {
if (!initCalled) {
throw new IllegalStateException("RackResolver class not yet initialized");
}
return coreResolve(hostName);
}
private static Node coreResolve(String hostName) {
List <String> tmpList = new ArrayList<String>(1);
tmpList.add(hostName);
List <String> rNameList = dnsToSwitchMapping.resolve(tmpList);
String rName = null;
if (rNameList == null || rNameList.get(0) == null) {
rName = NetworkTopology.DEFAULT_RACK;
LOG.info("Couldn't resolve " + hostName + ". Falling back to "
+ NetworkTopology.DEFAULT_RACK);
} else {
rName = rNameList.get(0);
LOG.info("Resolved " + hostName + " to " + rName);
}
return new NodeBase(hostName, rName);
}
/**
* Only used by tests
*/
@Private
@VisibleForTesting
static DNSToSwitchMapping getDnsToSwitchMapping(){
return dnsToSwitchMapping;
}
}