/* * 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.sling.discovery.impl.common; import java.util.Date; import java.util.HashSet; import java.util.Iterator; import java.util.Set; import org.apache.sling.api.resource.Resource; import org.apache.sling.api.resource.ResourceResolver; import org.apache.sling.api.resource.ValueMap; import org.apache.sling.discovery.impl.Config; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** helper for views **/ public class ViewHelper { private static final Logger logger = LoggerFactory .getLogger(ViewHelper.class); /** * Return the list of cluster instances that are 'live', ie that have * sent a heartbeat within the configured heartbeat timeout * @param clusterInstancesResource * @param config * @return */ public static Set<String> determineLiveInstances( final Resource clusterInstancesResource, final Config config) { final Set<String> myView = new HashSet<String>(); final Iterator<Resource> it = clusterInstancesResource.getChildren() .iterator(); while (it.hasNext()) { Resource aClusterInstance = it.next(); if (isHeartBeatCurrent(aClusterInstance, config)) { myView.add(aClusterInstance.getName()); } } return myView; } /** * Chck if the given resource has a heartbeat sent within the * configured heartbeat timeout * @param aClusterInstanceResource * @param config * @return */ private static boolean isHeartBeatCurrent( Resource aClusterInstanceResource, final Config config) { final ValueMap properties = aClusterInstanceResource.adaptTo(ValueMap.class); final Date lastHeartbeat = properties.get("lastHeartbeat", Date.class); final long now = System.currentTimeMillis(); if (lastHeartbeat == null) { return false; } final long then = lastHeartbeat.getTime(); final long diff = now - then; return (diff < config.getHeartbeatTimeoutMillis()); } /** * Return the currently established cluster view - or null if there is no * cluster view established at the moment. * * @param resourceResolver * @return */ public static View getEstablishedView(final ResourceResolver resourceResolver, final Config config) { final Resource establishedParent = resourceResolver .getResource(config.getEstablishedViewPath()); if (establishedParent == null) { logger.debug("getEstablishedView: no established view found: {}", config.getEstablishedViewPath()); return null; } final Iterable<Resource> children = establishedParent.getChildren(); if (children == null) { logger.debug("getEstablishedView: no children found of {}", establishedParent); return null; } final Iterator<Resource> it = children.iterator(); if (!it.hasNext()) { logger.debug("getEstablishedView: no it of children of {}", establishedParent); return null; } Resource establishedView = it.next(); if (!it.hasNext()) { return new View(establishedView); } // emergency cleanup in case there is more than one established view: while (true) { logger.error("getEstablishedView: more than one established view encountered! Removing: " + establishedView); new View(establishedView).remove(false); if (!it.hasNext()) { return null; } establishedView = it.next(); } } }