| /* |
| * 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.bookkeeper.common.resolver; |
| |
| import com.google.common.base.Function; |
| import com.google.common.collect.Lists; |
| import io.grpc.NameResolver; |
| import io.grpc.NameResolverProvider; |
| import io.grpc.internal.DnsNameResolverProvider; |
| import java.net.URI; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| import javax.annotation.Nullable; |
| import lombok.extern.slf4j.Slf4j; |
| import org.apache.bookkeeper.common.net.ServiceURI; |
| import org.apache.bookkeeper.common.util.SharedResourceManager.Resource; |
| |
| /** |
| * An implementation of {@link NameResolverProvider} that provides {@link NameResolver}s |
| * to resolve {@link org.apache.bookkeeper.common.net.ServiceURI}. |
| */ |
| @Slf4j |
| public final class ServiceNameResolverProvider extends NameResolverFactoryProvider { |
| |
| private final DnsNameResolverProvider dnsProvider; |
| private final Resource<ExecutorService> executorResource; |
| |
| public ServiceNameResolverProvider() { |
| this.dnsProvider = new DnsNameResolverProvider(); |
| this.executorResource = new Resource<ExecutorService>() { |
| @Override |
| public ExecutorService create() { |
| return Executors.newSingleThreadScheduledExecutor(); |
| } |
| |
| @Override |
| public void close(ExecutorService instance) { |
| instance.shutdown(); |
| } |
| }; |
| } |
| |
| @Override |
| protected boolean isAvailable() { |
| return true; |
| } |
| |
| @Override |
| protected int priority() { |
| return 10; |
| } |
| |
| @Nullable |
| @Override |
| public NameResolver newNameResolver(URI targetUri, NameResolver.Args params) { |
| ServiceURI serviceURI; |
| try { |
| serviceURI = ServiceURI.create(targetUri); |
| } catch (NullPointerException | IllegalArgumentException e) { |
| // invalid uri here, so return null to allow grpc to use other name resolvers |
| log.info("ServiceNameResolverProvider doesn't know how to resolve {} : cause {}", |
| targetUri, e.getMessage()); |
| return null; |
| } |
| |
| if (null == serviceURI.getServiceName() |
| || ServiceURI.SERVICE_BK.equals(serviceURI.getServiceName())) { |
| |
| String[] hosts = serviceURI.getServiceHosts(); |
| if (hosts.length == 0) { |
| // no host is find, so return null to let grpc choose other resolver. |
| return null; |
| } else if (hosts.length == 1) { |
| // create a dns name resolver |
| URI dnsUri = URI.create("dns:///" + hosts[0]); |
| return dnsProvider.newNameResolver(dnsUri, params); |
| } else { |
| // create a static resolver taking the list of servers. |
| List<String> hostList = new ArrayList<>(); |
| for (String host : hosts) { |
| hostList.add(host); |
| } |
| List<URI> hostUris = Lists.transform( |
| hostList, |
| new Function<String, URI>() { |
| @Nullable |
| @Override |
| public URI apply(@Nullable String host) { |
| return URI.create("//" + host); |
| } |
| } |
| ); |
| |
| return new StaticNameResolver( |
| "static", |
| executorResource, |
| hostUris); |
| } |
| } else { |
| return null; |
| } |
| } |
| |
| @Override |
| public String getDefaultScheme() { |
| return ServiceURI.SERVICE_BK; |
| } |
| |
| @Override |
| public NameResolver.Factory toFactory() { |
| return new NameResolverProviderFactory(Lists.newArrayList(this)); |
| } |
| |
| } |