ambari-server/src/main/java/org/apache/ambari/server/agent/stomp/AmbariSubscriptionRegistry.java - ambari - 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.ambari.server.agent.stomp;

 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;

 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
 import org.springframework.expression.ExpressionParser;
 import org.springframework.expression.PropertyAccessor;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.SimpleEvaluationContext;
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
 import org.springframework.messaging.simp.broker.AbstractSubscriptionRegistry;
 import org.springframework.messaging.simp.broker.SubscriptionRegistry;
 import org.springframework.messaging.support.MessageHeaderAccessor;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.PathMatcher;

 import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;

 /**
  * Implementation of {@link SubscriptionRegistry} that has configurable cache size, optimized working with cache and
  * destinations matching.
  */
 public class AmbariSubscriptionRegistry extends AbstractSubscriptionRegistry {
   private static final Logger LOG = LoggerFactory.getLogger(AmbariSubscriptionRegistry.class);

   /** Static evaluation context to reuse. */
   private static final EvaluationContext messageEvalContext =
       SimpleEvaluationContext.forPropertyAccessors(new SimpMessageHeaderPropertyAccessor()).build();

   private PathMatcher pathMatcher = new AntPathMatcher();

   private volatile int cacheLimit;

   private String selectorHeaderName = "selector";

   private volatile boolean selectorHeaderInUse = false;

   private final ExpressionParser expressionParser = new SpelExpressionParser();

   private final DestinationCache destinationCache;

   private final SessionSubscriptionRegistry subscriptionRegistry = new SessionSubscriptionRegistry();

   public AmbariSubscriptionRegistry(int cacheLimit) {
     this.cacheLimit = cacheLimit;
     destinationCache = new DestinationCache();
   }

   /**
    * Specify the {@link PathMatcher} to use.
    */
   public void setPathMatcher(PathMatcher pathMatcher) {
     this.pathMatcher = pathMatcher;
   }

   /**
    * Return the configured {@link PathMatcher}.
    */
   public PathMatcher getPathMatcher() {
     return this.pathMatcher;
   }

   /**
    * Specify the maximum number of entries for the resolved destination cache.
    * Default is 1024.
    */
   public void setCacheLimit(int cacheLimit) {
     this.cacheLimit = cacheLimit;
   }

   /**
    * Return the maximum number of entries for the resolved destination cache.
    */
   public int getCacheLimit() {
     return this.cacheLimit;
   }

   /**
    * Configure the name of a selector header that a subscription message can
    * have in order to filter messages based on their headers. The value of the
    * header can use Spring EL expressions against message headers.
    * <p>For example the following expression expects a header called "foo" to
    * have the value "bar":
    * <pre>
    * headers.foo == 'bar'
    * </pre>
    * <p>By default this is set to "selector".
    * @since 4.2
    */
   public void setSelectorHeaderName(String selectorHeaderName) {
     Assert.notNull(selectorHeaderName, "'selectorHeaderName' must not be null");
     this.selectorHeaderName = selectorHeaderName;
   }

   /**
    * Return the name for the selector header.
    * @since 4.2
    */
   public String getSelectorHeaderName() {
     return this.selectorHeaderName;
   }


   @Override
   protected void addSubscriptionInternal(
       String sessionId, String subsId, String destination, Message<?> message) {

     Expression expression = getSelectorExpression(message.getHeaders());
     this.subscriptionRegistry.addSubscription(sessionId, subsId, destination, expression);
     this.destinationCache.updateAfterNewSubscription(destination, sessionId, subsId);
   }

   @Nullable
   private Expression getSelectorExpression(MessageHeaders headers) {
     Expression expression = null;
     if (getSelectorHeaderName() != null) {
       String selector = SimpMessageHeaderAccessor.getFirstNativeHeader(getSelectorHeaderName(), headers);
       if (selector != null) {
         try {
           expression = this.expressionParser.parseExpression(selector);
           this.selectorHeaderInUse = true;
           if (logger.isTraceEnabled()) {
             logger.trace("Subscription selector: [" + selector + "]");
           }
         }
         catch (Throwable ex) {
           if (logger.isDebugEnabled()) {
             logger.debug("Failed to parse selector: " + selector, ex);
           }
         }
       }
     }
     return expression;
   }

   @Override
   protected void removeSubscriptionInternal(String sessionId, String subsId, Message<?> message) {
     SessionSubscriptionInfo info = this.subscriptionRegistry.getSubscriptions(sessionId);
     if (info != null) {
       String destination = info.removeSubscription(subsId);
       if (destination != null) {
         this.destinationCache.updateAfterRemovedSubscription(sessionId, subsId);
       }
     }
   }

   @Override
   public void unregisterAllSubscriptions(String sessionId) {
     SessionSubscriptionInfo info = this.subscriptionRegistry.removeSubscriptions(sessionId);
     if (info != null) {
       this.destinationCache.updateAfterRemovedSession(info);
     }
   }

   @Override
   protected MultiValueMap<String, String> findSubscriptionsInternal(String destination, Message<?> message) {
     MultiValueMap<String, String> result = this.destinationCache.getSubscriptions(destination, message);
     return filterSubscriptions(result, message);
   }

   private MultiValueMap<String, String> filterSubscriptions(
       MultiValueMap<String, String> allMatches, Message<?> message) {

     if (!this.selectorHeaderInUse) {
       return allMatches;
     }
     MultiValueMap<String, String> result = new LinkedMultiValueMap<>(allMatches.size());
     allMatches.forEach((sessionId, subIds) -> {
       subIds.forEach(subId -> {
         SessionSubscriptionInfo info = this.subscriptionRegistry.getSubscriptions(sessionId);
         if (info == null) {
           return;
         }
         Subscription sub = info.getSubscription(subId);
         if (sub == null) {
           return;
         }
         Expression expression = sub.getSelectorExpression();
         if (expression == null) {
           result.add(sessionId, subId);
           return;
         }
         try {
           if (Boolean.TRUE.equals(expression.getValue(messageEvalContext, message, Boolean.class))) {
             result.add(sessionId, subId);
           }
         }
         catch (SpelEvaluationException ex) {
           if (logger.isDebugEnabled()) {
             logger.debug("Failed to evaluate selector: " + ex.getMessage());
           }
         }
         catch (Throwable ex) {
           logger.debug("Failed to evaluate selector", ex);
         }
       });
     });
     return result;
   }

   @Override
   public String toString() {
     return "DefaultSubscriptionRegistry[" + this.destinationCache + ", " + this.subscriptionRegistry + "]";
   }


   /**
    * A cache for destinations previously resolved via
    * {@link org.springframework.messaging.simp.broker.DefaultSubscriptionRegistry#findSubscriptionsInternal(String, Message)}
    */
   private class DestinationCache {

     /** Map from destination -> <sessionId, subscriptionId> for fast look-ups */
     private final Map<String, LinkedMultiValueMap<String, String>> accessCache =
         new ConcurrentHashMap<>(cacheLimit);

     //TODO optimize usage of this cache on perf cluster
     private final Cache<String, String> notSubscriptionCache =
         CacheBuilder.newBuilder().maximumSize(cacheLimit).build();

     public LinkedMultiValueMap<String, String> getSubscriptions(String destination, Message<?> message) {
       LinkedMultiValueMap<String, String> copiedSubscriptions = new LinkedMultiValueMap<>();
       if (notSubscriptionCache.asMap().keySet().contains(destination)) {
         return copiedSubscriptions;
       }
       this.accessCache.compute(destination, (key, value) -> {
         if (value == null) {
           LinkedMultiValueMap<String, String> result = new LinkedMultiValueMap<>();
           subscriptionRegistry.getAllSubscriptions().forEach((info) -> {
             info.getDestinations().forEach((destinationPattern) -> {
               //TODO temporary changed to more fast-acting check without regex, need move investigation
               if (destinationPattern.equals(destination)) {
                 info.getSubscriptions(destinationPattern).forEach((subscription) -> {
                   result.add(info.sessionId, subscription.getId());
                 });
               }
             });
           });
           if (!result.isEmpty()) {
             copiedSubscriptions.addAll(result.deepCopy());
             return result;
           } else {
             notSubscriptionCache.put(destination, "");
             return null;
           }
         } else {
           copiedSubscriptions.addAll(value.deepCopy());
           return value;
         }
       });
       return copiedSubscriptions;
     }

     public void updateAfterNewSubscription(String destination, String sessionId, String subsId) {
       LinkedMultiValueMap<String, String> updatedMap = this.accessCache.computeIfPresent(destination, (key, value) -> {
         if (getPathMatcher().match(destination, key)) {
           LinkedMultiValueMap<String, String> subs = value;
           subs.add(sessionId, subsId);
           return subs;
         }
         return value;
       });
       if (updatedMap == null) {
         this.notSubscriptionCache.invalidate(destination);
       }
     }

     public void updateAfterRemovedSubscription(String sessionId, String subsId) {
       for (Iterator<Map.Entry<String, LinkedMultiValueMap<String, String>>> iterator =
            this.accessCache.entrySet().iterator(); iterator.hasNext(); ) {
         Map.Entry<String, LinkedMultiValueMap<String, String>> entry = iterator.next();
         String destination = entry.getKey();
         this.accessCache.compute(destination, (key, value) -> {
           if (value != null) {
             List<String> subscriptions = value.get(sessionId);
             if (subscriptions != null) {
               subscriptions.remove(subsId);
               if (subscriptions.isEmpty()) {
                 value.remove(sessionId);
               }
               if (value.isEmpty()) {
                 return null;
               } else {
                 this.notSubscriptionCache.invalidate(destination);
               }
             }
           }
           return value;
         });
       }
     }

     public void updateAfterRemovedSession(SessionSubscriptionInfo info) {
       for (Iterator<Map.Entry<String, LinkedMultiValueMap<String, String>>> iterator =
            this.accessCache.entrySet().iterator(); iterator.hasNext(); ) {
         Map.Entry<String, LinkedMultiValueMap<String, String>> entry = iterator.next();
         String destination = entry.getKey();
         this.accessCache.compute(destination, (key, value) -> {
           if (value != null) {
             if (value.remove(info.getSessionId()) != null) {
               if (value.isEmpty()) {
                 return null;
               } else {
                 this.notSubscriptionCache.invalidate(destination);
               }
             }
           }
           return value;
         });
       }
     }

     @Override
     public String toString() {
       return "cache[" + this.accessCache.size() + " destination(s)]";
     }
   }


   /**
    * Provide access to session subscriptions by sessionId.
    */
   private static class SessionSubscriptionRegistry {

     // sessionId -> SessionSubscriptionInfo
     private final ConcurrentMap<String, SessionSubscriptionInfo> sessions = new ConcurrentHashMap<>();

     @Nullable
     public SessionSubscriptionInfo getSubscriptions(String sessionId) {
       return this.sessions.get(sessionId);
     }

     public Collection<SessionSubscriptionInfo> getAllSubscriptions() {
       return this.sessions.values();
     }

     public SessionSubscriptionInfo addSubscription(String sessionId, String subscriptionId,
                                                    String destination, @Nullable Expression selectorExpression) {

       SessionSubscriptionInfo info = this.sessions.get(sessionId);
       if (info == null) {
         info = new SessionSubscriptionInfo(sessionId);
         SessionSubscriptionInfo value = this.sessions.putIfAbsent(sessionId, info);
         if (value != null) {
           info = value;
         }
       }
       info.addSubscription(destination, subscriptionId, selectorExpression);
       return info;
     }

     @Nullable
     public SessionSubscriptionInfo removeSubscriptions(String sessionId) {
       return this.sessions.remove(sessionId);
     }

     @Override
     public String toString() {
       return "registry[" + this.sessions.size() + " sessions]";
     }
   }


   /**
    * Hold subscriptions for a session.
    */
   private static class SessionSubscriptionInfo {

     private final String sessionId;

     // destination -> subscriptions
     private final Map<String, Set<Subscription>> destinationLookup = new ConcurrentHashMap<>(4);

     public SessionSubscriptionInfo(String sessionId) {
       Assert.notNull(sessionId, "'sessionId' must not be null");
       this.sessionId = sessionId;
     }

     public String getSessionId() {
       return this.sessionId;
     }

     public Set<String> getDestinations() {
       return this.destinationLookup.keySet();
     }

     public Set<Subscription> getSubscriptions(String destination) {
       return this.destinationLookup.get(destination);
     }

     @Nullable
     public Subscription getSubscription(String subscriptionId) {
       for (Map.Entry<String, Set<Subscription>> destinationEntry :
           this.destinationLookup.entrySet()) {
         for (Subscription sub : destinationEntry.getValue()) {
           if (sub.getId().equalsIgnoreCase(subscriptionId)) {
             return sub;
           }
         }
       }
       return null;
     }

     public void addSubscription(String destination, String subscriptionId, @Nullable Expression selectorExpression) {
       Set<Subscription> subs = this.destinationLookup.get(destination);
       if (subs == null) {
         synchronized (this.destinationLookup) {
           subs = this.destinationLookup.get(destination);
           if (subs == null) {
             subs = new CopyOnWriteArraySet<>();
             this.destinationLookup.put(destination, subs);
           }
         }
       }
       subs.add(new Subscription(subscriptionId, selectorExpression));
     }

     @Nullable
     public String removeSubscription(String subscriptionId) {
       for (Map.Entry<String, Set<Subscription>> destinationEntry :
           this.destinationLookup.entrySet()) {
         Set<Subscription> subs = destinationEntry.getValue();
         if (subs != null) {
           for (Subscription sub : subs) {
             if (sub.getId().equals(subscriptionId) && subs.remove(sub)) {
               synchronized (this.destinationLookup) {
                 if (subs.isEmpty()) {
                   this.destinationLookup.remove(destinationEntry.getKey());
                 }
               }
               return destinationEntry.getKey();
             }
           }
         }
       }
       return null;
     }

     @Override
     public String toString() {
       return "[sessionId=" + this.sessionId + ", subscriptions=" + this.destinationLookup + "]";
     }
   }


   private static final class Subscription {

     private final String id;

     @Nullable
     private final Expression selectorExpression;

     public Subscription(String id, @Nullable Expression selector) {
       Assert.notNull(id, "Subscription id must not be null");
       this.id = id;
       this.selectorExpression = selector;
     }

     public String getId() {
       return this.id;
     }

     @Nullable
     public Expression getSelectorExpression() {
       return this.selectorExpression;
     }

     @Override
     public boolean equals(Object other) {
       return (this == other || (other instanceof Subscription && this.id.equals(((Subscription) other).id)));
     }

     @Override
     public int hashCode() {
       return this.id.hashCode();
     }

     @Override
     public String toString() {
       return "subscription(id=" + this.id + ")";
     }
   }


   private static class SimpMessageHeaderPropertyAccessor implements PropertyAccessor {

     @Override
     public Class<?>[] getSpecificTargetClasses() {
       return new Class<?>[]{Message.class, MessageHeaders.class};
     }

     @Override
     public boolean canRead(EvaluationContext context, @Nullable Object target, String name) {
       return true;
     }

     @Override
     public TypedValue read(EvaluationContext context, @Nullable Object target, String name) {
       Object value;
       if (target instanceof Message) {
         value = name.equals("headers") ? ((Message) target).getHeaders() : null;
       } else if (target instanceof MessageHeaders) {
         MessageHeaders headers = (MessageHeaders) target;
         SimpMessageHeaderAccessor accessor =
             MessageHeaderAccessor.getAccessor(headers, SimpMessageHeaderAccessor.class);
         Assert.state(accessor != null, "No SimpMessageHeaderAccessor");
         if ("destination".equalsIgnoreCase(name)) {
           value = accessor.getDestination();
         } else {
           value = accessor.getFirstNativeHeader(name);
           if (value == null) {
             value = headers.get(name);
           }
         }
       } else {
         // Should never happen...
         throw new IllegalStateException("Expected Message or MessageHeaders.");
       }
       return new TypedValue(value);
     }

     @Override
     public boolean canWrite(EvaluationContext context, @Nullable Object target, String name) {
       return false;
     }

     @Override
     public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object value) {
     }
   }

 }
	/**
	* 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.ambari.server.agent.stomp;

	import java.util.Collection;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;
	import java.util.concurrent.ConcurrentHashMap;
	import java.util.concurrent.ConcurrentMap;
	import java.util.concurrent.CopyOnWriteArraySet;

	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;
	import org.springframework.expression.EvaluationContext;
	import org.springframework.expression.Expression;
	import org.springframework.expression.ExpressionParser;
	import org.springframework.expression.PropertyAccessor;
	import org.springframework.expression.TypedValue;
	import org.springframework.expression.spel.SpelEvaluationException;
	import org.springframework.expression.spel.standard.SpelExpressionParser;
	import org.springframework.expression.spel.support.SimpleEvaluationContext;
	import org.springframework.lang.Nullable;
	import org.springframework.messaging.Message;
	import org.springframework.messaging.MessageHeaders;
	import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
	import org.springframework.messaging.simp.broker.AbstractSubscriptionRegistry;
	import org.springframework.messaging.simp.broker.SubscriptionRegistry;
	import org.springframework.messaging.support.MessageHeaderAccessor;
	import org.springframework.util.AntPathMatcher;
	import org.springframework.util.Assert;
	import org.springframework.util.LinkedMultiValueMap;
	import org.springframework.util.MultiValueMap;
	import org.springframework.util.PathMatcher;

	import com.google.common.cache.Cache;
	import com.google.common.cache.CacheBuilder;

	/**
	* Implementation of {@link SubscriptionRegistry} that has configurable cache size, optimized working with cache and
	* destinations matching.
	*/
	public class AmbariSubscriptionRegistry extends AbstractSubscriptionRegistry {
	private static final Logger LOG = LoggerFactory.getLogger(AmbariSubscriptionRegistry.class);

	/** Static evaluation context to reuse. */
	private static final EvaluationContext messageEvalContext =
	SimpleEvaluationContext.forPropertyAccessors(new SimpMessageHeaderPropertyAccessor()).build();

	private PathMatcher pathMatcher = new AntPathMatcher();

	private volatile int cacheLimit;

	private String selectorHeaderName = "selector";

	private volatile boolean selectorHeaderInUse = false;

	private final ExpressionParser expressionParser = new SpelExpressionParser();

	private final DestinationCache destinationCache;

	private final SessionSubscriptionRegistry subscriptionRegistry = new SessionSubscriptionRegistry();

	public AmbariSubscriptionRegistry(int cacheLimit) {
	this.cacheLimit = cacheLimit;
	destinationCache = new DestinationCache();
	}

	/**
	* Specify the {@link PathMatcher} to use.
	*/
	public void setPathMatcher(PathMatcher pathMatcher) {
	this.pathMatcher = pathMatcher;
	}

	/**
	* Return the configured {@link PathMatcher}.
	*/
	public PathMatcher getPathMatcher() {
	return this.pathMatcher;
	}

	/**
	* Specify the maximum number of entries for the resolved destination cache.
	* Default is 1024.
	*/
	public void setCacheLimit(int cacheLimit) {
	this.cacheLimit = cacheLimit;
	}

	/**
	* Return the maximum number of entries for the resolved destination cache.
	*/
	public int getCacheLimit() {
	return this.cacheLimit;
	}

	/**
	* Configure the name of a selector header that a subscription message can
	* have in order to filter messages based on their headers. The value of the
	* header can use Spring EL expressions against message headers.
	* <p>For example the following expression expects a header called "foo" to
	* have the value "bar":
	* <pre>
	* headers.foo == 'bar'
	* </pre>
	* <p>By default this is set to "selector".
	* @since 4.2
	*/
	public void setSelectorHeaderName(String selectorHeaderName) {
	Assert.notNull(selectorHeaderName, "'selectorHeaderName' must not be null");
	this.selectorHeaderName = selectorHeaderName;
	}

	/**
	* Return the name for the selector header.
	* @since 4.2
	*/
	public String getSelectorHeaderName() {
	return this.selectorHeaderName;
	}


	@Override
	protected void addSubscriptionInternal(
	String sessionId, String subsId, String destination, Message<?> message) {

	Expression expression = getSelectorExpression(message.getHeaders());
	this.subscriptionRegistry.addSubscription(sessionId, subsId, destination, expression);
	this.destinationCache.updateAfterNewSubscription(destination, sessionId, subsId);
	}

	@Nullable
	private Expression getSelectorExpression(MessageHeaders headers) {
	Expression expression = null;
	if (getSelectorHeaderName() != null) {
	String selector = SimpMessageHeaderAccessor.getFirstNativeHeader(getSelectorHeaderName(), headers);
	if (selector != null) {
	try {
	expression = this.expressionParser.parseExpression(selector);
	this.selectorHeaderInUse = true;
	if (logger.isTraceEnabled()) {
	logger.trace("Subscription selector: [" + selector + "]");
	}
	}
	catch (Throwable ex) {
	if (logger.isDebugEnabled()) {
	logger.debug("Failed to parse selector: " + selector, ex);
	}
	}
	}
	}
	return expression;
	}

	@Override
	protected void removeSubscriptionInternal(String sessionId, String subsId, Message<?> message) {
	SessionSubscriptionInfo info = this.subscriptionRegistry.getSubscriptions(sessionId);
	if (info != null) {
	String destination = info.removeSubscription(subsId);
	if (destination != null) {
	this.destinationCache.updateAfterRemovedSubscription(sessionId, subsId);
	}
	}
	}

	@Override
	public void unregisterAllSubscriptions(String sessionId) {
	SessionSubscriptionInfo info = this.subscriptionRegistry.removeSubscriptions(sessionId);
	if (info != null) {
	this.destinationCache.updateAfterRemovedSession(info);
	}
	}

	@Override
	protected MultiValueMap<String, String> findSubscriptionsInternal(String destination, Message<?> message) {
	MultiValueMap<String, String> result = this.destinationCache.getSubscriptions(destination, message);
	return filterSubscriptions(result, message);
	}

	private MultiValueMap<String, String> filterSubscriptions(
	MultiValueMap<String, String> allMatches, Message<?> message) {

	if (!this.selectorHeaderInUse) {
	return allMatches;
	}
	MultiValueMap<String, String> result = new LinkedMultiValueMap<>(allMatches.size());
	allMatches.forEach((sessionId, subIds) -> {
	subIds.forEach(subId -> {
	SessionSubscriptionInfo info = this.subscriptionRegistry.getSubscriptions(sessionId);
	if (info == null) {
	return;
	}
	Subscription sub = info.getSubscription(subId);
	if (sub == null) {
	return;
	}
	Expression expression = sub.getSelectorExpression();
	if (expression == null) {
	result.add(sessionId, subId);
	return;
	}
	try {
	if (Boolean.TRUE.equals(expression.getValue(messageEvalContext, message, Boolean.class))) {
	result.add(sessionId, subId);
	}
	}
	catch (SpelEvaluationException ex) {
	if (logger.isDebugEnabled()) {
	logger.debug("Failed to evaluate selector: " + ex.getMessage());
	}
	}
	catch (Throwable ex) {
	logger.debug("Failed to evaluate selector", ex);
	}
	});
	});
	return result;
	}

	@Override
	public String toString() {
	return "DefaultSubscriptionRegistry[" + this.destinationCache + ", " + this.subscriptionRegistry + "]";
	}


	/**
	* A cache for destinations previously resolved via
	* {@link org.springframework.messaging.simp.broker.DefaultSubscriptionRegistry#findSubscriptionsInternal(String, Message)}
	*/
	private class DestinationCache {

	/** Map from destination -> <sessionId, subscriptionId> for fast look-ups */
	private final Map<String, LinkedMultiValueMap<String, String>> accessCache =
	new ConcurrentHashMap<>(cacheLimit);

	//TODO optimize usage of this cache on perf cluster
	private final Cache<String, String> notSubscriptionCache =
	CacheBuilder.newBuilder().maximumSize(cacheLimit).build();

	public LinkedMultiValueMap<String, String> getSubscriptions(String destination, Message<?> message) {
	LinkedMultiValueMap<String, String> copiedSubscriptions = new LinkedMultiValueMap<>();
	if (notSubscriptionCache.asMap().keySet().contains(destination)) {
	return copiedSubscriptions;
	}
	this.accessCache.compute(destination, (key, value) -> {
	if (value == null) {
	LinkedMultiValueMap<String, String> result = new LinkedMultiValueMap<>();
	subscriptionRegistry.getAllSubscriptions().forEach((info) -> {
	info.getDestinations().forEach((destinationPattern) -> {
	//TODO temporary changed to more fast-acting check without regex, need move investigation
	if (destinationPattern.equals(destination)) {
	info.getSubscriptions(destinationPattern).forEach((subscription) -> {
	result.add(info.sessionId, subscription.getId());
	});
	}
	});
	});
	if (!result.isEmpty()) {
	copiedSubscriptions.addAll(result.deepCopy());
	return result;
	} else {
	notSubscriptionCache.put(destination, "");
	return null;
	}
	} else {
	copiedSubscriptions.addAll(value.deepCopy());
	return value;
	}
	});
	return copiedSubscriptions;
	}

	public void updateAfterNewSubscription(String destination, String sessionId, String subsId) {
	LinkedMultiValueMap<String, String> updatedMap = this.accessCache.computeIfPresent(destination, (key, value) -> {
	if (getPathMatcher().match(destination, key)) {
	LinkedMultiValueMap<String, String> subs = value;
	subs.add(sessionId, subsId);
	return subs;
	}
	return value;
	});
	if (updatedMap == null) {
	this.notSubscriptionCache.invalidate(destination);
	}
	}

	public void updateAfterRemovedSubscription(String sessionId, String subsId) {
	for (Iterator<Map.Entry<String, LinkedMultiValueMap<String, String>>> iterator =
	this.accessCache.entrySet().iterator(); iterator.hasNext(); ) {
	Map.Entry<String, LinkedMultiValueMap<String, String>> entry = iterator.next();
	String destination = entry.getKey();
	this.accessCache.compute(destination, (key, value) -> {
	if (value != null) {
	List<String> subscriptions = value.get(sessionId);
	if (subscriptions != null) {
	subscriptions.remove(subsId);
	if (subscriptions.isEmpty()) {
	value.remove(sessionId);
	}
	if (value.isEmpty()) {
	return null;
	} else {
	this.notSubscriptionCache.invalidate(destination);
	}
	}
	}
	return value;
	});
	}
	}

	public void updateAfterRemovedSession(SessionSubscriptionInfo info) {
	for (Iterator<Map.Entry<String, LinkedMultiValueMap<String, String>>> iterator =
	this.accessCache.entrySet().iterator(); iterator.hasNext(); ) {
	Map.Entry<String, LinkedMultiValueMap<String, String>> entry = iterator.next();
	String destination = entry.getKey();
	this.accessCache.compute(destination, (key, value) -> {
	if (value != null) {
	if (value.remove(info.getSessionId()) != null) {
	if (value.isEmpty()) {
	return null;
	} else {
	this.notSubscriptionCache.invalidate(destination);
	}
	}
	}
	return value;
	});
	}
	}

	@Override
	public String toString() {
	return "cache[" + this.accessCache.size() + " destination(s)]";
	}
	}


	/**
	* Provide access to session subscriptions by sessionId.
	*/
	private static class SessionSubscriptionRegistry {

	// sessionId -> SessionSubscriptionInfo
	private final ConcurrentMap<String, SessionSubscriptionInfo> sessions = new ConcurrentHashMap<>();

	@Nullable
	public SessionSubscriptionInfo getSubscriptions(String sessionId) {
	return this.sessions.get(sessionId);
	}

	public Collection<SessionSubscriptionInfo> getAllSubscriptions() {
	return this.sessions.values();
	}

	public SessionSubscriptionInfo addSubscription(String sessionId, String subscriptionId,
	String destination, @Nullable Expression selectorExpression) {

	SessionSubscriptionInfo info = this.sessions.get(sessionId);
	if (info == null) {
	info = new SessionSubscriptionInfo(sessionId);
	SessionSubscriptionInfo value = this.sessions.putIfAbsent(sessionId, info);
	if (value != null) {
	info = value;
	}
	}
	info.addSubscription(destination, subscriptionId, selectorExpression);
	return info;
	}

	@Nullable
	public SessionSubscriptionInfo removeSubscriptions(String sessionId) {
	return this.sessions.remove(sessionId);
	}

	@Override
	public String toString() {
	return "registry[" + this.sessions.size() + " sessions]";
	}
	}


	/**
	* Hold subscriptions for a session.
	*/
	private static class SessionSubscriptionInfo {

	private final String sessionId;

	// destination -> subscriptions
	private final Map<String, Set<Subscription>> destinationLookup = new ConcurrentHashMap<>(4);

	public SessionSubscriptionInfo(String sessionId) {
	Assert.notNull(sessionId, "'sessionId' must not be null");
	this.sessionId = sessionId;
	}

	public String getSessionId() {
	return this.sessionId;
	}

	public Set<String> getDestinations() {
	return this.destinationLookup.keySet();
	}

	public Set<Subscription> getSubscriptions(String destination) {
	return this.destinationLookup.get(destination);
	}

	@Nullable
	public Subscription getSubscription(String subscriptionId) {
	for (Map.Entry<String, Set<Subscription>> destinationEntry :
	this.destinationLookup.entrySet()) {
	for (Subscription sub : destinationEntry.getValue()) {
	if (sub.getId().equalsIgnoreCase(subscriptionId)) {
	return sub;
	}
	}
	}
	return null;
	}

	public void addSubscription(String destination, String subscriptionId, @Nullable Expression selectorExpression) {
	Set<Subscription> subs = this.destinationLookup.get(destination);
	if (subs == null) {
	synchronized (this.destinationLookup) {
	subs = this.destinationLookup.get(destination);
	if (subs == null) {
	subs = new CopyOnWriteArraySet<>();
	this.destinationLookup.put(destination, subs);
	}
	}
	}
	subs.add(new Subscription(subscriptionId, selectorExpression));
	}

	@Nullable
	public String removeSubscription(String subscriptionId) {
	for (Map.Entry<String, Set<Subscription>> destinationEntry :
	this.destinationLookup.entrySet()) {
	Set<Subscription> subs = destinationEntry.getValue();
	if (subs != null) {
	for (Subscription sub : subs) {
	if (sub.getId().equals(subscriptionId) && subs.remove(sub)) {
	synchronized (this.destinationLookup) {
	if (subs.isEmpty()) {
	this.destinationLookup.remove(destinationEntry.getKey());
	}
	}
	return destinationEntry.getKey();
	}
	}
	}
	}
	return null;
	}

	@Override
	public String toString() {
	return "[sessionId=" + this.sessionId + ", subscriptions=" + this.destinationLookup + "]";
	}
	}


	private static final class Subscription {

	private final String id;

	@Nullable
	private final Expression selectorExpression;

	public Subscription(String id, @Nullable Expression selector) {
	Assert.notNull(id, "Subscription id must not be null");
	this.id = id;
	this.selectorExpression = selector;
	}

	public String getId() {
	return this.id;
	}

	@Nullable
	public Expression getSelectorExpression() {
	return this.selectorExpression;
	}

	@Override
	public boolean equals(Object other) {
	return (this == other \|\| (other instanceof Subscription && this.id.equals(((Subscription) other).id)));
	}

	@Override
	public int hashCode() {
	return this.id.hashCode();
	}

	@Override
	public String toString() {
	return "subscription(id=" + this.id + ")";
	}
	}


	private static class SimpMessageHeaderPropertyAccessor implements PropertyAccessor {

	@Override
	public Class<?>[] getSpecificTargetClasses() {
	return new Class<?>[]{Message.class, MessageHeaders.class};
	}

	@Override
	public boolean canRead(EvaluationContext context, @Nullable Object target, String name) {
	return true;
	}

	@Override
	public TypedValue read(EvaluationContext context, @Nullable Object target, String name) {
	Object value;
	if (target instanceof Message) {
	value = name.equals("headers") ? ((Message) target).getHeaders() : null;
	} else if (target instanceof MessageHeaders) {
	MessageHeaders headers = (MessageHeaders) target;
	SimpMessageHeaderAccessor accessor =
	MessageHeaderAccessor.getAccessor(headers, SimpMessageHeaderAccessor.class);
	Assert.state(accessor != null, "No SimpMessageHeaderAccessor");
	if ("destination".equalsIgnoreCase(name)) {
	value = accessor.getDestination();
	} else {
	value = accessor.getFirstNativeHeader(name);
	if (value == null) {
	value = headers.get(name);
	}
	}
	} else {
	// Should never happen...
	throw new IllegalStateException("Expected Message or MessageHeaders.");
	}
	return new TypedValue(value);
	}

	@Override
	public boolean canWrite(EvaluationContext context, @Nullable Object target, String name) {
	return false;
	}

	@Override
	public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object value) {
	}
	}

	}