/*
* Copyright 2002-2018 the original author or authors.
*
* Licensed 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.springframework.messaging.simp.broker;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
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.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.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 org.springframework.util.StringUtils;
/**
* Implementation of {@link SubscriptionRegistry} that stores subscriptions
* in memory and uses a {@link org.springframework.util.PathMatcher PathMatcher}
* for matching destinations.
*
* <p>As of 4.2, this class supports a {@link #setSelectorHeaderName selector}
* header on subscription messages with Spring EL expressions evaluated against
* the headers to filter out messages in addition to destination matching.
*
* @author Rossen Stoyanchev
* @author Sebastien Deleuze
* @author Juergen Hoeller
* @since 4.0
*/
public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
/** Default maximum number of entries for the destination cache: 1024. */
public static final int DEFAULT_CACHE_LIMIT = 1024;
/** Static evaluation context to reuse. */
private static final EvaluationContext messageEvalContext =
SimpleEvaluationContext.forPropertyAccessors(new SimpMessageHeaderPropertyAccessor()).build();
private PathMatcher pathMatcher = new AntPathMatcher();
private volatile int cacheLimit = DEFAULT_CACHE_LIMIT;
@Nullable
private String selectorHeaderName = "selector";
private volatile boolean selectorHeaderInUse = false;
private final ExpressionParser expressionParser = new SpelExpressionParser();
private final DestinationCache destinationCache = new DestinationCache();
private final SessionSubscriptionRegistry subscriptionRegistry = new SessionSubscriptionRegistry();
/**
* 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 header that a subscription message can have for
* the purpose of filtering messages matched to the subscription. The header
* value is expected to be a Spring EL boolean expression to be applied to
* the headers of messages matched to the subscription.
* <p>For example:
* <pre>
* headers.foo == 'bar'
* </pre>
* <p>By default this is set to "selector". You can set it to a different
* name, or to {@code null} to turn off support for a selector header.
* @param selectorHeaderName the name to use for a selector header
* @since 4.2
*/
public void setSelectorHeaderName(@Nullable String selectorHeaderName) {
this.selectorHeaderName = (StringUtils.hasText(selectorHeaderName) ? selectorHeaderName : null);
}
/**
* Return the name for the selector header name.
* @since 4.2
*/
@Nullable
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) -> {
for (String subId : subIds) {
SessionSubscriptionInfo info = this.subscriptionRegistry.getSubscriptions(sessionId);
if (info == null) {
continue;
}
Subscription sub = info.getSubscription(subId);
if (sub == null) {
continue;
}
Expression expression = sub.getSelectorExpression();
if (expression == null) {
result.add(sessionId, subId);
continue;
}
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 DefaultSubscriptionRegistry#findSubscriptionsInternal(String, Message)}.
*/
private class DestinationCache {
/** Map from destination to {@code <sessionId, subscriptionId>} for fast look-ups. */
private final Map<String, LinkedMultiValueMap<String, String>> accessCache =
new ConcurrentHashMap<>(DEFAULT_CACHE_LIMIT);
/** Map from destination to {@code <sessionId, subscriptionId>} with locking. */
@SuppressWarnings("serial")
private final Map<String, LinkedMultiValueMap<String, String>> updateCache =
new LinkedHashMap<String, LinkedMultiValueMap<String, String>>(DEFAULT_CACHE_LIMIT, 0.75f, true) {
@Override
protected boolean removeEldestEntry(Map.Entry<String, LinkedMultiValueMap<String, String>> eldest) {
if (size() > getCacheLimit()) {
accessCache.remove(eldest.getKey());
return true;
}
else {
return false;
}
}
};
public LinkedMultiValueMap<String, String> getSubscriptions(String destination, Message<?> message) {
LinkedMultiValueMap<String, String> result = this.accessCache.get(destination);
if (result == null) {
synchronized (this.updateCache) {
result = new LinkedMultiValueMap<>();
for (SessionSubscriptionInfo info : subscriptionRegistry.getAllSubscriptions()) {
for (String destinationPattern : info.getDestinations()) {
if (getPathMatcher().match(destinationPattern, destination)) {
for (Subscription sub : info.getSubscriptions(destinationPattern)) {
result.add(info.sessionId, sub.getId());
}
}
}
}
if (!result.isEmpty()) {
this.updateCache.put(destination, result.deepCopy());
this.accessCache.put(destination, result);
}
}
}
return result;
}
public void updateAfterNewSubscription(String destination, String sessionId, String subsId) {
synchronized (this.updateCache) {
this.updateCache.forEach((cachedDestination, subscriptions) -> {
if (getPathMatcher().match(destination, cachedDestination)) {
// Subscription id's may also be populated via getSubscriptions()
List<String> subsForSession = subscriptions.get(sessionId);
if (subsForSession == null || !subsForSession.contains(subsId)) {
subscriptions.add(sessionId, subsId);
this.accessCache.put(cachedDestination, subscriptions.deepCopy());
}
}
});
}
}
public void updateAfterRemovedSubscription(String sessionId, String subsId) {
synchronized (this.updateCache) {
Set<String> destinationsToRemove = new HashSet<>();
this.updateCache.forEach((destination, sessionMap) -> {
List<String> subscriptions = sessionMap.get(sessionId);
if (subscriptions != null) {
subscriptions.remove(subsId);
if (subscriptions.isEmpty()) {
sessionMap.remove(sessionId);
}
if (sessionMap.isEmpty()) {
destinationsToRemove.add(destination);
}
else {
this.accessCache.put(destination, sessionMap.deepCopy());
}
}
});
for (String destination : destinationsToRemove) {
this.updateCache.remove(destination);
this.accessCache.remove(destination);
}
}
}
public void updateAfterRemovedSession(SessionSubscriptionInfo info) {
synchronized (this.updateCache) {
Set<String> destinationsToRemove = new HashSet<>();
this.updateCache.forEach((destination, sessionMap) -> {
if (sessionMap.remove(info.getSessionId()) != null) {
if (sessionMap.isEmpty()) {
destinationsToRemove.add(destination);
}
else {
this.accessCache.put(destination, sessionMap.deepCopy());
}
}
});
for (String destination : destinationsToRemove) {
this.updateCache.remove(destination);
this.accessCache.remove(destination);
}
}
}
@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<DefaultSubscriptionRegistry.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<DefaultSubscriptionRegistry.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) {
}
}
}
