jack-moseley commented on a change in pull request #2620: [GOBBLIN-756] Add flow catalog that updates when filesystem is modified URL: https://github.com/apache/incubator-gobblin/pull/2620#discussion_r279474556
########## File path: gobblin-service/src/main/java/org/apache/gobblin/service/modules/template_catalog/UpdatingFSFlowTemplateCatalog.java ########## @@ -0,0 +1,108 @@ +/* + * 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.gobblin.service.modules.template_catalog; + +import java.io.IOException; +import java.net.URI; +import java.net.URISyntaxException; +import java.util.List; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; + +import org.apache.hadoop.fs.Path; + +import com.typesafe.config.Config; + +import lombok.extern.slf4j.Slf4j; + +import org.apache.gobblin.runtime.api.JobTemplate; +import org.apache.gobblin.runtime.api.SpecNotFoundException; +import org.apache.gobblin.service.modules.template.FlowTemplate; +import org.apache.gobblin.util.filesystem.PathAlterationListener; +import org.apache.gobblin.util.filesystem.PathAlterationListenerAdaptor; + + +/** + * {@link FSFlowTemplateCatalog} that keeps a cache of flow and job templates. It has a + * {@link org.apache.gobblin.util.filesystem.PathAlterationListener} on the root path, and clears the cache when a change + * is detected so that the next call to {@link #getFlowTemplate(URI)} will use the updated files. + */ +@Slf4j +public class UpdatingFSFlowTemplateCatalog extends FSFlowTemplateCatalog { + private static Map<URI, FlowTemplate> flowTemplateMap = new ConcurrentHashMap<>(); + private static Map<URI, List<JobTemplate>> jobTemplateMap = new ConcurrentHashMap<>(); + + public UpdatingFSFlowTemplateCatalog(Config sysConfig) throws IOException { + super(sysConfig); + } + + @Override + public FlowTemplate getFlowTemplate(URI flowTemplateDirURI) + throws SpecNotFoundException, JobTemplate.TemplateException, IOException, URISyntaxException { + if (!flowTemplateMap.containsKey(flowTemplateDirURI)) { + flowTemplateMap.put(flowTemplateDirURI, super.getFlowTemplate(flowTemplateDirURI)); + } + return flowTemplateMap.get(flowTemplateDirURI); + } + + @Override + public List<JobTemplate> getJobTemplatesForFlow(URI flowTemplateDirURI) + throws IOException, SpecNotFoundException, JobTemplate.TemplateException, URISyntaxException { + if (!jobTemplateMap.containsKey(flowTemplateDirURI)) { + jobTemplateMap.put(flowTemplateDirURI, super.getJobTemplatesForFlow(flowTemplateDirURI)); + } + return jobTemplateMap.get(flowTemplateDirURI); + } + + @Override + protected PathAlterationListener getListener() { + return new FlowCatalogPathAlterationListener(); + } + + @Override + protected void startUp() throws IOException { + if (this.pathAlterationDetector != null) { + this.pathAlterationDetector.start(); + } + } + + /** + * Clear cached templates so they will be reloaded next time {@link #getFlowTemplate(URI)} is called. + */ + public void clearTemplates() { + log.info("Change detected, reloading flow templates."); + flowTemplateMap.clear(); + jobTemplateMap.clear(); + } + + /** + * {@link org.apache.gobblin.util.filesystem.PathAlterationListener} that clears job template cache if a file is + * created or updated. + */ + private class FlowCatalogPathAlterationListener extends PathAlterationListenerAdaptor { + @Override + public void onFileCreate(Path path) { + clearTemplates(); + } + + @Override + public void onFileChange(Path path) { + clearTemplates(); Review comment: There are cases where, for example, a job template could get updated and multiple flow templates are pointing to that job template, so we would have to figure out which flows used that job template and invalidate those as well. Due to this I think it's easier to just clear entire cache. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
