oak-store-composite/src/main/java/org/apache/jackrabbit/oak/composite/CompositeNodeStoreService.java - jackrabbit-oak - Git at Google

 /*
  * 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.jackrabbit.oak.composite;

 import com.google.common.io.Closer;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.ConfigurationPolicy;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Property;
 import org.apache.felix.scr.annotations.PropertyUnbounded;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.ReferencePolicy;
 import org.apache.jackrabbit.oak.api.CommitFailedException;
 import org.apache.jackrabbit.oak.api.jmx.CheckpointMBean;
 import org.apache.jackrabbit.oak.commons.PropertiesUtil;
 import org.apache.jackrabbit.oak.composite.checks.NodeStoreChecks;
 import org.apache.jackrabbit.oak.osgi.OsgiWhiteboard;
 import org.apache.jackrabbit.oak.spi.commit.ObserverTracker;
 import org.apache.jackrabbit.oak.spi.mount.Mount;
 import org.apache.jackrabbit.oak.spi.mount.MountInfoProvider;
 import org.apache.jackrabbit.oak.spi.state.NodeStore;
 import org.apache.jackrabbit.oak.spi.state.NodeStoreProvider;
 import org.apache.jackrabbit.oak.spi.whiteboard.Registration;
 import org.apache.jackrabbit.oak.spi.whiteboard.Whiteboard;
 import org.apache.jackrabbit.oak.spi.whiteboard.WhiteboardUtils;
 import org.apache.jackrabbit.oak.stats.StatisticsProvider;
 import org.osgi.framework.Constants;
 import org.osgi.framework.ServiceRegistration;
 import org.osgi.service.component.ComponentContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Dictionary;
 import java.util.HashSet;
 import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import static com.google.common.collect.Sets.newIdentityHashSet;

 @Component(policy = ConfigurationPolicy.REQUIRE)
 public class CompositeNodeStoreService {

     private static final Logger LOG = LoggerFactory.getLogger(CompositeNodeStoreService.class);

     private static final String GLOBAL_ROLE = "composite:global";

     private static final String MOUNT_ROLE_PREFIX = "composite:mount:";

     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.STATIC)
     private MountInfoProvider mountInfoProvider;

     @Reference(cardinality = ReferenceCardinality.MANDATORY_MULTIPLE, policy = ReferencePolicy.DYNAMIC, bind = "bindNodeStore", unbind = "unbindNodeStore", referenceInterface = NodeStoreProvider.class, target="(!(service.pid=org.apache.jackrabbit.oak.composite.CompositeNodeStore))")
     private List<NodeStoreWithProps> nodeStores = new ArrayList<>();

     @Reference
     private NodeStoreChecks checks;

     @Reference
     private StatisticsProvider statisticsProvider = StatisticsProvider.NOOP;

     @Property(label = "Ignore read only writes",
             unbounded = PropertyUnbounded.ARRAY,
             description = "Writes to these read-only paths won't fail the commit"
     )
     private static final String PROP_IGNORE_READ_ONLY_WRITES = "ignoreReadOnlyWrites";

     @Property(label = "Read-only mounts",
             description = "The partial stores should be configured as read-only",
             boolValue = true
     )
     private static final String PROP_PARTIAL_READ_ONLY = "partialReadOnly";

     @Property(label = "Pre-populate seed mount",
             description = "Setting this parameter to a mount name will enable pre-populating the empty default store"
     )
     private static final String PROP_SEED_MOUNT = "seedMount";

     @Property(label = "Gather path statistics",
             description = "Whether the CompositeNodeStoreStatsMBean should gather information about the most popular paths (may be expensive)",
             boolValue = false
     )
     private static final String PATH_STATS = "pathStats";

     private ComponentContext context;

     private Set<NodeStoreProvider> nodeStoresInUse = newIdentityHashSet();

     private ServiceRegistration nsReg;

     private Closer mbeanRegistrations;

     private ObserverTracker observerTracker;

     private String[] ignoreReadOnlyWritePaths;

     private boolean partialReadOnly;

     private String seedMount;

     private boolean pathStats;

     @Activate
     protected void activate(ComponentContext context, Map<String, ?> config) throws IOException, CommitFailedException {
         this.context = context;
         ignoreReadOnlyWritePaths = PropertiesUtil.toStringArray(config.get(PROP_IGNORE_READ_ONLY_WRITES), new String[0]);
         partialReadOnly = PropertiesUtil.toBoolean(config.get(PROP_PARTIAL_READ_ONLY), true);
         seedMount = PropertiesUtil.toString(config.get(PROP_SEED_MOUNT), null);
         pathStats = PropertiesUtil.toBoolean(config.get(PATH_STATS), false);
         registerCompositeNodeStore();
     }

     @Deactivate
     protected void deactivate() throws IOException {
         unregisterCompositeNodeStore();
     }

     private void registerCompositeNodeStore() throws IOException, CommitFailedException {
         if (nsReg != null) {
             return; // already registered
         }

         NodeStoreWithProps globalNs = null;
         Set<String> availableMounts = new HashSet<>();
         for (NodeStoreWithProps ns : nodeStores) {
             if (isGlobalNodeStore(ns)) {
                 globalNs = ns;
             } else {
                 availableMounts.add(getMountName(ns));
             }
         }

         if (globalNs == null) {
             LOG.info("Composite node store registration is deferred until there's a global node store registered in OSGi");
             return;
         } else {
             LOG.info("Found global node store: {}", globalNs.getDescription());
         }

         for (Mount m : mountInfoProvider.getNonDefaultMounts()) {
             if (!availableMounts.contains(m.getName())) {
                 LOG.info("Composite node store registration is deferred until there's mount {} registered in OSGi", m.getName());
                 return;
             }
         }
         LOG.info("Node stores for all configured mounts are available");

         CompositeNodeStore.Builder builder = new CompositeNodeStore.Builder(mountInfoProvider, globalNs.getNodeStoreProvider().getNodeStore());
         nodeStoresInUse.add(globalNs.getNodeStoreProvider());

         builder.with(checks);
         builder.setPartialReadOnly(partialReadOnly);
         for (String p : ignoreReadOnlyWritePaths) {
             builder.addIgnoredReadOnlyWritePath(p);
         }

         for (NodeStoreWithProps ns : nodeStores) {
             if (isGlobalNodeStore(ns)) {
                 continue;
             }
             String mountName = getMountName(ns);
             if (mountName == null) {
                 continue;
             }

             builder.addMount(mountName, ns.getNodeStoreProvider().getNodeStore());
             LOG.info("Mounting {} as {}", ns.getDescription(), mountName);
             nodeStoresInUse.add(ns.getNodeStoreProvider());

             if (mountName.equals(seedMount)) {
                 new InitialContentMigrator(globalNs.nodeStore.getNodeStore(), ns.getNodeStoreProvider().getNodeStore(), mountInfoProvider.getMountByName(seedMount)).migrate();
             }
         }

         CompositeNodeStoreStats nodeStateStats = new CompositeNodeStoreStats(statisticsProvider, "NODE_STATE", pathStats);
         CompositeNodeStoreStats nodeBuilderStats = new CompositeNodeStoreStats(statisticsProvider, "NODE_BUILDER", pathStats);
         builder.with(nodeStateStats, nodeBuilderStats);

         Dictionary<String, Object> props = new Hashtable<String, Object>();
         props.put(Constants.SERVICE_PID, CompositeNodeStore.class.getName());
         props.put("oak.nodestore.description", new String[] { "nodeStoreType=compositeStore" } );

         CompositeNodeStore store = builder.build();

         observerTracker = new ObserverTracker(store);
         observerTracker.start(context.getBundleContext());

         Whiteboard whiteboard = new OsgiWhiteboard(context.getBundleContext());

         mbeanRegistrations = Closer.create();
         registerMBean(whiteboard,
                 CheckpointMBean.class,
                 new CompositeCheckpointMBean(store),
                 CheckpointMBean.TYPE,
                 "Composite node store checkpoint management");
         registerMBean(whiteboard,
                 CompositeNodeStoreStatsMBean.class,
                 nodeStateStats,
                 CompositeNodeStoreStatsMBean.TYPE,
                 "Composite node store statistics (node state)");
         registerMBean(whiteboard,
                 CompositeNodeStoreStatsMBean.class,
                 nodeBuilderStats,
                 CompositeNodeStoreStatsMBean.TYPE,
                 "Composite node store statistics (node builder)");

         LOG.info("Registering the composite node store");
         nsReg = context.getBundleContext().registerService(
                 new String[]{
                         NodeStore.class.getName()
                 },
                 store,
                 props);
     }

     private <T> void registerMBean(Whiteboard whiteboard,
                           Class<T> iface, T bean, String type, String name) {
         Registration reg = WhiteboardUtils.registerMBean(whiteboard, iface, bean, type, name);
         mbeanRegistrations.register(() -> reg.unregister());
     }

     private boolean isGlobalNodeStore(NodeStoreWithProps ns) {
         return GLOBAL_ROLE.equals(ns.getRole());
     }

     private String getMountName(NodeStoreWithProps ns) {
         String role = ns.getRole();
         if (role == null) {
             return null;
         }
         if (!role.startsWith(MOUNT_ROLE_PREFIX)) {
             return null;
         }
         return role.substring(MOUNT_ROLE_PREFIX.length());
     }

     private void unregisterCompositeNodeStore() throws IOException {
         if (nsReg != null) {
             LOG.info("Unregistering the composite node store");
             nsReg.unregister();
             nsReg = null;
         }
         if (mbeanRegistrations != null) {
             mbeanRegistrations.close();
             mbeanRegistrations = null;
         }
         if (observerTracker != null) {
             observerTracker.stop();
             observerTracker = null;
         }
         nodeStoresInUse.clear();
     }

     protected void bindNodeStore(NodeStoreProvider ns, Map<String, ?> config) throws IOException, CommitFailedException {
         NodeStoreWithProps newNs = new NodeStoreWithProps(ns, config);
         nodeStores.add(newNs);

         if (context == null) {
             LOG.info("bindNodeStore: context is null, delaying reconfiguration");
             return;
         }

         if (nsReg == null) {
             registerCompositeNodeStore();
         }
     }

     protected void unbindNodeStore(NodeStoreProvider ns) throws IOException {
         Iterator<NodeStoreWithProps> it = nodeStores.iterator();
         while (it.hasNext()) {
             if (it.next().getNodeStoreProvider() == ns) {
                 it.remove();
             }
         }

         if (context == null) {
             LOG.info("unbindNodeStore: context is null, delaying reconfiguration");
             return;
         }

         if (nsReg != null && nodeStoresInUse.contains(ns)) {
             unregisterCompositeNodeStore();
         }
     }

     private static class NodeStoreWithProps {

         private final NodeStoreProvider nodeStore;

         private final Map<String, ?> props;

         public NodeStoreWithProps(NodeStoreProvider nodeStore, Map<String, ?> props) {
             this.nodeStore = nodeStore;
             this.props = props;
         }

         public NodeStoreProvider getNodeStoreProvider() {
             return nodeStore;
         }

         public Map<String, ?> getProps() {
             return props;
         }

         public String getRole() {
             return PropertiesUtil.toString(props.get(NodeStoreProvider.ROLE), null);
         }

         public String getDescription() {
             return PropertiesUtil.toString(getProps().get("oak.nodestore.description"),
                     getNodeStoreProvider().getClass().toString());
         }
     }
 }
	/*
	* 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.jackrabbit.oak.composite;

	import com.google.common.io.Closer;
	import org.apache.felix.scr.annotations.Activate;
	import org.apache.felix.scr.annotations.Component;
	import org.apache.felix.scr.annotations.ConfigurationPolicy;
	import org.apache.felix.scr.annotations.Deactivate;
	import org.apache.felix.scr.annotations.Property;
	import org.apache.felix.scr.annotations.PropertyUnbounded;
	import org.apache.felix.scr.annotations.Reference;
	import org.apache.felix.scr.annotations.ReferenceCardinality;
	import org.apache.felix.scr.annotations.ReferencePolicy;
	import org.apache.jackrabbit.oak.api.CommitFailedException;
	import org.apache.jackrabbit.oak.api.jmx.CheckpointMBean;
	import org.apache.jackrabbit.oak.commons.PropertiesUtil;
	import org.apache.jackrabbit.oak.composite.checks.NodeStoreChecks;
	import org.apache.jackrabbit.oak.osgi.OsgiWhiteboard;
	import org.apache.jackrabbit.oak.spi.commit.ObserverTracker;
	import org.apache.jackrabbit.oak.spi.mount.Mount;
	import org.apache.jackrabbit.oak.spi.mount.MountInfoProvider;
	import org.apache.jackrabbit.oak.spi.state.NodeStore;
	import org.apache.jackrabbit.oak.spi.state.NodeStoreProvider;
	import org.apache.jackrabbit.oak.spi.whiteboard.Registration;
	import org.apache.jackrabbit.oak.spi.whiteboard.Whiteboard;
	import org.apache.jackrabbit.oak.spi.whiteboard.WhiteboardUtils;
	import org.apache.jackrabbit.oak.stats.StatisticsProvider;
	import org.osgi.framework.Constants;
	import org.osgi.framework.ServiceRegistration;
	import org.osgi.service.component.ComponentContext;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	import java.io.IOException;
	import java.util.ArrayList;
	import java.util.Dictionary;
	import java.util.HashSet;
	import java.util.Hashtable;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import static com.google.common.collect.Sets.newIdentityHashSet;

	@Component(policy = ConfigurationPolicy.REQUIRE)
	public class CompositeNodeStoreService {

	private static final Logger LOG = LoggerFactory.getLogger(CompositeNodeStoreService.class);

	private static final String GLOBAL_ROLE = "composite:global";

	private static final String MOUNT_ROLE_PREFIX = "composite:mount:";

	@Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY, policy = ReferencePolicy.STATIC)
	private MountInfoProvider mountInfoProvider;

	@Reference(cardinality = ReferenceCardinality.MANDATORY_MULTIPLE, policy = ReferencePolicy.DYNAMIC, bind = "bindNodeStore", unbind = "unbindNodeStore", referenceInterface = NodeStoreProvider.class, target="(!(service.pid=org.apache.jackrabbit.oak.composite.CompositeNodeStore))")
	private List<NodeStoreWithProps> nodeStores = new ArrayList<>();

	@Reference
	private NodeStoreChecks checks;

	@Reference
	private StatisticsProvider statisticsProvider = StatisticsProvider.NOOP;

	@Property(label = "Ignore read only writes",
	unbounded = PropertyUnbounded.ARRAY,
	description = "Writes to these read-only paths won't fail the commit"
	)
	private static final String PROP_IGNORE_READ_ONLY_WRITES = "ignoreReadOnlyWrites";

	@Property(label = "Read-only mounts",
	description = "The partial stores should be configured as read-only",
	boolValue = true
	)
	private static final String PROP_PARTIAL_READ_ONLY = "partialReadOnly";

	@Property(label = "Pre-populate seed mount",
	description = "Setting this parameter to a mount name will enable pre-populating the empty default store"
	)
	private static final String PROP_SEED_MOUNT = "seedMount";

	@Property(label = "Gather path statistics",
	description = "Whether the CompositeNodeStoreStatsMBean should gather information about the most popular paths (may be expensive)",
	boolValue = false
	)
	private static final String PATH_STATS = "pathStats";

	private ComponentContext context;

	private Set<NodeStoreProvider> nodeStoresInUse = newIdentityHashSet();

	private ServiceRegistration nsReg;

	private Closer mbeanRegistrations;

	private ObserverTracker observerTracker;

	private String[] ignoreReadOnlyWritePaths;

	private boolean partialReadOnly;

	private String seedMount;

	private boolean pathStats;

	@Activate
	protected void activate(ComponentContext context, Map<String, ?> config) throws IOException, CommitFailedException {
	this.context = context;
	ignoreReadOnlyWritePaths = PropertiesUtil.toStringArray(config.get(PROP_IGNORE_READ_ONLY_WRITES), new String[0]);
	partialReadOnly = PropertiesUtil.toBoolean(config.get(PROP_PARTIAL_READ_ONLY), true);
	seedMount = PropertiesUtil.toString(config.get(PROP_SEED_MOUNT), null);
	pathStats = PropertiesUtil.toBoolean(config.get(PATH_STATS), false);
	registerCompositeNodeStore();
	}

	@Deactivate
	protected void deactivate() throws IOException {
	unregisterCompositeNodeStore();
	}

	private void registerCompositeNodeStore() throws IOException, CommitFailedException {
	if (nsReg != null) {
	return; // already registered
	}

	NodeStoreWithProps globalNs = null;
	Set<String> availableMounts = new HashSet<>();
	for (NodeStoreWithProps ns : nodeStores) {
	if (isGlobalNodeStore(ns)) {
	globalNs = ns;
	} else {
	availableMounts.add(getMountName(ns));
	}
	}

	if (globalNs == null) {
	LOG.info("Composite node store registration is deferred until there's a global node store registered in OSGi");
	return;
	} else {
	LOG.info("Found global node store: {}", globalNs.getDescription());
	}

	for (Mount m : mountInfoProvider.getNonDefaultMounts()) {
	if (!availableMounts.contains(m.getName())) {
	LOG.info("Composite node store registration is deferred until there's mount {} registered in OSGi", m.getName());
	return;
	}
	}
	LOG.info("Node stores for all configured mounts are available");

	CompositeNodeStore.Builder builder = new CompositeNodeStore.Builder(mountInfoProvider, globalNs.getNodeStoreProvider().getNodeStore());
	nodeStoresInUse.add(globalNs.getNodeStoreProvider());

	builder.with(checks);
	builder.setPartialReadOnly(partialReadOnly);
	for (String p : ignoreReadOnlyWritePaths) {
	builder.addIgnoredReadOnlyWritePath(p);
	}

	for (NodeStoreWithProps ns : nodeStores) {
	if (isGlobalNodeStore(ns)) {
	continue;
	}
	String mountName = getMountName(ns);
	if (mountName == null) {
	continue;
	}

	builder.addMount(mountName, ns.getNodeStoreProvider().getNodeStore());
	LOG.info("Mounting {} as {}", ns.getDescription(), mountName);
	nodeStoresInUse.add(ns.getNodeStoreProvider());

	if (mountName.equals(seedMount)) {
	new InitialContentMigrator(globalNs.nodeStore.getNodeStore(), ns.getNodeStoreProvider().getNodeStore(), mountInfoProvider.getMountByName(seedMount)).migrate();
	}
	}

	CompositeNodeStoreStats nodeStateStats = new CompositeNodeStoreStats(statisticsProvider, "NODE_STATE", pathStats);
	CompositeNodeStoreStats nodeBuilderStats = new CompositeNodeStoreStats(statisticsProvider, "NODE_BUILDER", pathStats);
	builder.with(nodeStateStats, nodeBuilderStats);

	Dictionary<String, Object> props = new Hashtable<String, Object>();
	props.put(Constants.SERVICE_PID, CompositeNodeStore.class.getName());
	props.put("oak.nodestore.description", new String[] { "nodeStoreType=compositeStore" } );

	CompositeNodeStore store = builder.build();

	observerTracker = new ObserverTracker(store);
	observerTracker.start(context.getBundleContext());

	Whiteboard whiteboard = new OsgiWhiteboard(context.getBundleContext());

	mbeanRegistrations = Closer.create();
	registerMBean(whiteboard,
	CheckpointMBean.class,
	new CompositeCheckpointMBean(store),
	CheckpointMBean.TYPE,
	"Composite node store checkpoint management");
	registerMBean(whiteboard,
	CompositeNodeStoreStatsMBean.class,
	nodeStateStats,
	CompositeNodeStoreStatsMBean.TYPE,
	"Composite node store statistics (node state)");
	registerMBean(whiteboard,
	CompositeNodeStoreStatsMBean.class,
	nodeBuilderStats,
	CompositeNodeStoreStatsMBean.TYPE,
	"Composite node store statistics (node builder)");

	LOG.info("Registering the composite node store");
	nsReg = context.getBundleContext().registerService(
	new String[]{
	NodeStore.class.getName()
	},
	store,
	props);
	}

	private <T> void registerMBean(Whiteboard whiteboard,
	Class<T> iface, T bean, String type, String name) {
	Registration reg = WhiteboardUtils.registerMBean(whiteboard, iface, bean, type, name);
	mbeanRegistrations.register(() -> reg.unregister());
	}

	private boolean isGlobalNodeStore(NodeStoreWithProps ns) {
	return GLOBAL_ROLE.equals(ns.getRole());
	}

	private String getMountName(NodeStoreWithProps ns) {
	String role = ns.getRole();
	if (role == null) {
	return null;
	}
	if (!role.startsWith(MOUNT_ROLE_PREFIX)) {
	return null;
	}
	return role.substring(MOUNT_ROLE_PREFIX.length());
	}

	private void unregisterCompositeNodeStore() throws IOException {
	if (nsReg != null) {
	LOG.info("Unregistering the composite node store");
	nsReg.unregister();
	nsReg = null;
	}
	if (mbeanRegistrations != null) {
	mbeanRegistrations.close();
	mbeanRegistrations = null;
	}
	if (observerTracker != null) {
	observerTracker.stop();
	observerTracker = null;
	}
	nodeStoresInUse.clear();
	}

	protected void bindNodeStore(NodeStoreProvider ns, Map<String, ?> config) throws IOException, CommitFailedException {
	NodeStoreWithProps newNs = new NodeStoreWithProps(ns, config);
	nodeStores.add(newNs);

	if (context == null) {
	LOG.info("bindNodeStore: context is null, delaying reconfiguration");
	return;
	}

	if (nsReg == null) {
	registerCompositeNodeStore();
	}
	}

	protected void unbindNodeStore(NodeStoreProvider ns) throws IOException {
	Iterator<NodeStoreWithProps> it = nodeStores.iterator();
	while (it.hasNext()) {
	if (it.next().getNodeStoreProvider() == ns) {
	it.remove();
	}
	}

	if (context == null) {
	LOG.info("unbindNodeStore: context is null, delaying reconfiguration");
	return;
	}

	if (nsReg != null && nodeStoresInUse.contains(ns)) {
	unregisterCompositeNodeStore();
	}
	}

	private static class NodeStoreWithProps {

	private final NodeStoreProvider nodeStore;

	private final Map<String, ?> props;

	public NodeStoreWithProps(NodeStoreProvider nodeStore, Map<String, ?> props) {
	this.nodeStore = nodeStore;
	this.props = props;
	}

	public NodeStoreProvider getNodeStoreProvider() {
	return nodeStore;
	}

	public Map<String, ?> getProps() {
	return props;
	}

	public String getRole() {
	return PropertiesUtil.toString(props.get(NodeStoreProvider.ROLE), null);
	}

	public String getDescription() {
	return PropertiesUtil.toString(getProps().get("oak.nodestore.description"),
	getNodeStoreProvider().getClass().toString());
	}
	}
	}