| /* |
| * 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.samza.coordinator.server; |
| |
| import java.io.IOException; |
| import java.util.Optional; |
| import javax.servlet.http.HttpServlet; |
| import javax.servlet.http.HttpServletRequest; |
| import javax.servlet.http.HttpServletResponse; |
| import org.apache.samza.container.LocalityManager; |
| import org.apache.samza.job.model.ProcessorLocality; |
| import org.apache.samza.job.model.LocalityModel; |
| import org.apache.samza.serializers.model.SamzaObjectMapper; |
| import org.codehaus.jackson.map.ObjectMapper; |
| |
| |
| /** |
| * A servlet for locality information of a job. The servlet is hosted alongside of the {@link JobServlet} which hosts |
| * job model and configuration. Historically, locality information was part of job model but we extracted the locality |
| * as job model is static within the lifecycle of an application attempt while locality changes in the event of container |
| * movements. The locality information is served under |
| * {@link org.apache.samza.coordinator.JobModelManager#server()}/locality. The server and the port information are |
| * dynamic and is determined at the start AM. YARN dashboard or job-coordinator logs contains the server |
| * and the port information. |
| * |
| * This separation enables us to achieve performance benefits by caching job model when it is served by the AM as it |
| * can incur significant penalty in the job start time for jobs with large number of containers. |
| */ |
| public class LocalityServlet extends HttpServlet { |
| private static final String PROCESSOR_ID_PARAM = "processorId"; |
| private final ObjectMapper mapper = SamzaObjectMapper.getObjectMapper(); |
| private final LocalityManager localityManager; |
| |
| public LocalityServlet(LocalityManager localityManager) { |
| this.localityManager = localityManager; |
| } |
| |
| @Override |
| public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { |
| response.setContentType("application/json"); |
| response.setStatus(HttpServletResponse.SC_OK); |
| LocalityModel localityModel = localityManager.readLocality(); |
| |
| if (request.getParameterMap().size() == 1) { |
| String processorId = request.getParameter(PROCESSOR_ID_PARAM); |
| ProcessorLocality processorLocality = Optional.ofNullable(localityModel.getProcessorLocality(processorId)) |
| .orElse(new ProcessorLocality(processorId, "")); |
| mapper.writeValue(response.getWriter(), processorLocality); |
| } else { |
| mapper.writeValue(response.getWriter(), localityModel); |
| } |
| } |
| } |