| /** |
| * 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.distributedlog.net; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| import org.apache.bookkeeper.net.DNSToSwitchMapping; |
| import org.apache.commons.lang.StringUtils; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| |
| /** |
| * Abstract DNS resolver for bookkeeper ensemble placement. |
| */ |
| public abstract class DNSResolver implements DNSToSwitchMapping { |
| static final Logger LOG = LoggerFactory.getLogger(DNSResolver.class); |
| |
| protected final ConcurrentMap<String, String> domainNameToNetworkLocation = |
| new ConcurrentHashMap<String, String>(); |
| |
| protected final ConcurrentMap<String, String> hostNameToRegion = |
| new ConcurrentHashMap<String, String>(); |
| |
| /** |
| * Construct the default dns resolver without host-region overrides. |
| */ |
| public DNSResolver() { |
| this(""); |
| } |
| |
| /** |
| * Construct the dns resolver with host-region overrides. |
| * |
| * <p><i>hostRegionOverrides</i> is a string of pairs of host-region mapping |
| * (host:region) separated by ';'. during dns resolution, the host will be resolved |
| * to override region. example: <i>host1:region1;host2:region2;...</i> |
| * |
| * @param hostRegionOverrides |
| * pairs of host-region mapping separated by ';' |
| */ |
| public DNSResolver(String hostRegionOverrides) { |
| if (StringUtils.isNotBlank(hostRegionOverrides)) { |
| // Host Region Overrides are of the form |
| // HN1:R1;HN2:R2;... |
| String[] overrides = hostRegionOverrides.split(";"); |
| |
| for (String override : overrides) { |
| String[] parts = override.split(":"); |
| if (parts.length != 2) { |
| LOG.warn("Incorrect override specified", override); |
| } else { |
| hostNameToRegion.putIfAbsent(parts[0], parts[1]); |
| } |
| } |
| } // otherwise, no overrides were specified |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public List<String> resolve(List<String> names) { |
| List<String> networkLocations = new ArrayList<String>(names.size()); |
| for (String name : names) { |
| networkLocations.add(resolve(name)); |
| } |
| return networkLocations; |
| } |
| |
| private String resolve(String domainName) { |
| String networkLocation = domainNameToNetworkLocation.get(domainName); |
| if (null == networkLocation) { |
| networkLocation = resolveToNetworkLocation(domainName); |
| domainNameToNetworkLocation.put(domainName, networkLocation); |
| } |
| return networkLocation; |
| } |
| |
| /** |
| * Resolve the <code>domainName</code> to its network location. |
| * |
| * @param domainName |
| * domain name |
| * @return the network location of <i>domainName</i> |
| */ |
| protected abstract String resolveToNetworkLocation(String domainName); |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void reloadCachedMappings() { |
| domainNameToNetworkLocation.clear(); |
| } |
| } |