/*
* 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.standalone;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.ReferencePolicy;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.discovery.ClusterView;
import org.apache.sling.discovery.DiscoveryService;
import org.apache.sling.discovery.InstanceDescription;
import org.apache.sling.discovery.InstanceFilter;
import org.apache.sling.discovery.PropertyProvider;
import org.apache.sling.discovery.TopologyEvent;
import org.apache.sling.discovery.TopologyEvent.Type;
import org.apache.sling.discovery.TopologyEventListener;
import org.apache.sling.discovery.TopologyView;
import org.apache.sling.settings.SlingSettingsService;
import org.osgi.framework.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This is a simple implementation of the discovery service
* which can be used for a cluster less installation (= single instance).
* It is disabled by default and can be enabled through a OSGi configuration.
*/
@Component(immediate=true)
@Service(value = {DiscoveryService.class})
public class NoClusterDiscoveryService implements DiscoveryService {
/** The logger. */
private final Logger logger = LoggerFactory.getLogger(this.getClass());
/**
* Sling settings service to get the Sling ID and run modes.
*/
@Reference
private SlingSettingsService settingsService;
/**
* All topology event listeners.
*/
@Reference(cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE, policy = ReferencePolicy.DYNAMIC)
private TopologyEventListener[] listeners = new TopologyEventListener[0];
/**
* All property providers.
*/
@Reference(cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE, policy = ReferencePolicy.DYNAMIC,
referenceInterface=PropertyProvider.class, updated="updatedPropertyProvider")
private List<ProviderInfo> providerInfos = new ArrayList<ProviderInfo>();
/**
* Special lock object to sync data structure access
*/
private final Object lock = new Object();
/**
* The current topology view.
*/
private TopologyView topologyView;
private Map<String, String> cachedProperties = new HashMap<String, String>();
/**
* Activate this service
* Create a new description.
*/
@Activate
protected void activate() {
logger.debug("NoClusterDiscoveryService started.");
final InstanceDescription myDescription = new InstanceDescription() {
public boolean isLocal() {
return true;
}
public boolean isLeader() {
return true;
}
public String getSlingId() {
return settingsService.getSlingId();
}
public String getProperty(final String name) {
synchronized(lock) {
return cachedProperties.get(name);
}
}
public Map<String, String> getProperties() {
synchronized(lock) {
return Collections.unmodifiableMap(cachedProperties);
}
}
public ClusterView getClusterView() {
final Collection<ClusterView> clusters = topologyView.getClusterViews();
if (clusters==null || clusters.size()==0) {
return null;
}
return clusters.iterator().next();
}
};
final Set<InstanceDescription> instances = new HashSet<InstanceDescription>();
instances.add(myDescription);
final TopologyEventListener[] registeredServices;
synchronized ( lock ) {
registeredServices = this.listeners;
final ClusterView clusterView = new ClusterView() {
public InstanceDescription getLeader() {
return myDescription;
}
public List<InstanceDescription> getInstances() {
return new LinkedList<InstanceDescription>(instances);
}
public String getId() {
return "0";
}
};
this.topologyView = new TopologyView() {
public InstanceDescription getLocalInstance() {
return myDescription;
}
public boolean isCurrent() {
return true;
}
public Set<InstanceDescription> getInstances() {
return instances;
}
public Set<InstanceDescription> findInstances(InstanceFilter picker) {
Set<InstanceDescription> result = new HashSet<InstanceDescription>();
for (Iterator<InstanceDescription> it = getTopology().getInstances().iterator(); it.hasNext();) {
InstanceDescription instance = it.next();
if (picker.accept(instance)) {
result.add(instance);
}
}
return result;
}
public Set<ClusterView> getClusterViews() {
Set<ClusterView> clusters = new HashSet<ClusterView>();
clusters.add(clusterView);
return clusters;
}
};
}
for(final TopologyEventListener da: registeredServices) {
da.handleTopologyEvent(new TopologyEvent(Type.TOPOLOGY_INIT, null, topologyView));
}
}
/**
* Deactivate this service.
*/
@Deactivate
protected void deactivate() {
logger.debug("NoClusterDiscoveryService stopped.");
this.topologyView = null;
}
/**
* Bind a new property provider.
*/
@SuppressWarnings("unused")
private void bindPropertyProvider(final PropertyProvider propertyProvider, final Map<String, Object> props) {
logger.debug("bindPropertyProvider: Binding PropertyProvider {}", propertyProvider);
final TopologyEventListener[] awares;
synchronized (lock) {
final ProviderInfo info = new ProviderInfo(propertyProvider, props);
this.providerInfos.add(info);
Collections.sort(this.providerInfos);
this.updatePropertiesCache();
if ( this.topologyView == null ) {
awares = null;
} else {
awares = this.listeners;
}
}
if ( awares != null ) {
for(final TopologyEventListener da : awares) {
da.handleTopologyEvent(new TopologyEvent(Type.PROPERTIES_CHANGED, this.topologyView, this.topologyView));
}
}
}
/**
* Update a property provider.
*/
@SuppressWarnings("unused")
private void updatedPropertyProvider(final PropertyProvider propertyProvider, final Map<String, Object> props) {
logger.debug("bindPropertyProvider: Updating PropertyProvider {}", propertyProvider);
this.unbindPropertyProvider(propertyProvider, props, false);
this.bindPropertyProvider(propertyProvider, props);
}
/**
* Unbind a property provider
*/
@SuppressWarnings("unused")
private void unbindPropertyProvider(final PropertyProvider propertyProvider, final Map<String, Object> props) {
this.unbindPropertyProvider(propertyProvider, props, true);
}
/**
* Unbind a property provider
*/
@SuppressWarnings("unused")
private void unbindPropertyProvider(final PropertyProvider propertyProvider,
final Map<String, Object> props,
final boolean inform) {
logger.debug("unbindPropertyProvider: Releasing PropertyProvider {}", propertyProvider);
final TopologyEventListener[] awares;
synchronized (lock) {
final ProviderInfo info = new ProviderInfo(propertyProvider, props);
this.providerInfos.remove(info);
this.updatePropertiesCache();
if ( this.topologyView == null ) {
awares = null;
} else {
awares = this.listeners;
}
}
if ( inform && awares != null ) {
for(final TopologyEventListener da : awares) {
da.handleTopologyEvent(new TopologyEvent(Type.PROPERTIES_CHANGED, this.topologyView, this.topologyView));
}
}
}
private void updatePropertiesCache() {
final Map<String, String> newProps = new HashMap<String, String>();
for(final ProviderInfo info : this.providerInfos) {
newProps.putAll(info.properties);
}
this.cachedProperties = newProps;
if ( this.logger.isDebugEnabled() ) {
this.logger.debug("New properties: {}", this.cachedProperties);
}
}
@SuppressWarnings("unused")
private void bindTopologyEventListener(final TopologyEventListener clusterAware) {
logger.debug("bindTopologyEventListener: Binding TopologyEventListener {}", clusterAware);
boolean inform = true;
synchronized (lock) {
List<TopologyEventListener> currentList = new ArrayList<TopologyEventListener>(
Arrays.asList(listeners));
currentList.add(clusterAware);
this.listeners = currentList.toArray(new TopologyEventListener[currentList.size()]);
if ( this.topologyView == null ) {
inform = false;
}
}
if ( inform ) {
clusterAware.handleTopologyEvent(new TopologyEvent(Type.TOPOLOGY_INIT, null, topologyView));
}
}
@SuppressWarnings("unused")
private void unbindTopologyEventListener(final TopologyEventListener clusterAware) {
logger.debug("unbindTopologyEventListener: Releasing TopologyEventListener {}", clusterAware);
synchronized (lock) {
List<TopologyEventListener> currentList = new ArrayList<TopologyEventListener>(
Arrays.asList(listeners));
currentList.remove(clusterAware);
this.listeners = currentList.toArray(new TopologyEventListener[currentList.size()]);
}
}
/**
* @see DiscoveryService#getTopology()
*/
public TopologyView getTopology() {
return topologyView;
}
/**
* Internal class caching some provider infos like service id and ranking.
*/
private final static class ProviderInfo implements Comparable<ProviderInfo> {
public final PropertyProvider provider;
public final int ranking;
public final long serviceId;
public final Map<String, String> properties = new HashMap<String, String>();
public ProviderInfo(final PropertyProvider provider, final Map<String, Object> serviceProps) {
this.provider = provider;
final Object sr = serviceProps.get(Constants.SERVICE_RANKING);
if ( sr == null || !(sr instanceof Integer)) {
this.ranking = 0;
} else {
this.ranking = (Integer)sr;
}
this.serviceId = (Long)serviceProps.get(Constants.SERVICE_ID);
final Object namesObj = serviceProps.get(PropertyProvider.PROPERTY_PROPERTIES);
if ( namesObj instanceof String ) {
final String val = provider.getProperty((String)namesObj);
if ( val != null ) {
this.properties.put((String)namesObj, val);
}
} else if ( namesObj instanceof String[] ) {
for(final String name : (String[])namesObj ) {
final String val = provider.getProperty(name);
if ( val != null ) {
this.properties.put(name, val);
}
}
}
}
/**
* @see java.lang.Comparable#compareTo(java.lang.Object)
*/
public int compareTo(final ProviderInfo o) {
// Sort by rank in ascending order.
if ( this.ranking < o.ranking ) {
return -1; // lower rank
} else if (this.ranking > o.ranking ) {
return 1; // higher rank
}
// If ranks are equal, then sort by service id in descending order.
return (this.serviceId < o.serviceId) ? 1 : -1;
}
@Override
public boolean equals(final Object obj) {
if ( obj instanceof ProviderInfo ) {
return ((ProviderInfo)obj).serviceId == this.serviceId;
}
return false;
}
@Override
public int hashCode() {
return provider.hashCode();
}
}
}