/*
* 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) {
return null;
}
final Iterable<Resource> children = establishedParent.getChildren();
if (children == null) {
return null;
}
final Iterator<Resource> it = children.iterator();
if (!it.hasNext()) {
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();
}
}
/**
* Check if the established view matches the given set of slingIds
*/
public static boolean establishedViewMatches(
final ResourceResolver resourceResolver, final Config config, final Set<String> view) {
final View establishedView = ViewHelper.getEstablishedView(resourceResolver, config);
if (establishedView == null) {
return false;
} else {
return (establishedView.matches(view));
}
}
}