Add SessionDestroyedEvent

Add support for SessionDestroyedEvent so that applications can detect
when a Spring Session has expired or explicitly deleted. This will
ensure that we can cleanup resources (i.e. WebSockets) can be cleaned up
when a Session ends.

Fixes gh-60

spring-session/src/main/java/org/springframework/session/MapSessionRepository.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.session;
 
+import org.springframework.session.events.SessionDestroyedEvent;
 import org.springframework.util.Assert;
 
 import java.util.Map;
@@ -25,6 +26,10 @@ import java.util.concurrent.ConcurrentHashMap;
  * {@link java.util.concurrent.ConcurrentHashMap} is used, but a custom {@link java.util.Map} can be injected to use
  * distributed maps provided by NoSQL stores like Redis and Hazelcast.
  *
+ * <p>
+ * The implementation does NOT support firing {@link SessionDestroyedEvent}.
+ * </p>
+ *
  * @author Rob Winch
  * @since 1.0
  */

spring-session/src/main/java/org/springframework/session/data/redis/RedisOperationsSessionRepository.java

@@ -30,6 +30,7 @@ import org.springframework.session.ExpiringSession;
 import org.springframework.session.MapSession;
 import org.springframework.session.Session;
 import org.springframework.session.SessionRepository;
+import org.springframework.session.events.SessionDestroyedEvent;
 import org.springframework.session.web.http.SessionRepositoryFilter;
 import org.springframework.util.Assert;
 
@@ -39,7 +40,8 @@ import org.springframework.util.Assert;
  * using Spring Data's
  * {@link org.springframework.data.redis.core.RedisOperations}. In a web
  * environment, this is typically used in combination with
- * {@link SessionRepositoryFilter}.
+ * {@link SessionRepositoryFilter}. This implementation supports
+ * {@link SessionDestroyedEvent} through {@link SessionMessageListener}.
  * </p>
  *
  * <h2>Creating a new instance</h2>

spring-session/src/main/java/org/springframework/session/data/redis/SessionMessageListener.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2013 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.session.data.redis;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.data.redis.connection.Message;
+import org.springframework.data.redis.connection.MessageListener;
+import org.springframework.session.events.SessionDestroyedEvent;
+import org.springframework.util.Assert;
+
+/**
+ * Listen for Redis {@link Message} notifications. If it is a "del" or "expired"
+ * translate into a {@link SessionDestroyedEvent}.
+ *
+ * @author Rob Winch
+ * @since 1.0
+ */
+public class SessionMessageListener implements MessageListener {
+    private static final Log logger = LogFactory.getLog(SessionMessageListener.class);
+
+    private final ApplicationEventPublisher eventPublisher;
+
+    /**
+     * Creates a new instance
+     *
+     * @param eventPublisher the {@link ApplicationEventPublisher} to use. Cannot be null.
+     */
+    public SessionMessageListener(ApplicationEventPublisher eventPublisher) {
+        Assert.notNull(eventPublisher, "eventPublisher cannot be null");
+        this.eventPublisher = eventPublisher;
+    }
+
+    @Override
+    public void onMessage(Message message, byte[] pattern) {
+        byte[] messageBody = message.getBody();
+        if(messageBody == null) {
+            return;
+        }
+        String body = new String(messageBody);
+        if(!("del".equals(body) || "expired".equals(body))) {
+            return;
+        }
+        String channel = new String(message.getChannel());
+        int beginIndex = channel.lastIndexOf(":") + 1;
+        int endIndex = channel.length();
+        String sessionId = channel.substring(beginIndex, endIndex);
+
+        publishEvent(new SessionDestroyedEvent(this, sessionId));
+    }
+
+    private void publishEvent(ApplicationEvent event) {
+        try {
+            this.eventPublisher.publishEvent(event);
+        }
+        catch (Throwable ex) {
+            logger.error("Error publishing " + event + ".", ex);
+        }
+    }
+
+}

spring-session/src/main/java/org/springframework/session/data/redis/config/annotation/web/http/RedisHttpSessionConfiguration.java

@@ -20,6 +20,7 @@ import java.util.Map;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportAware;
@@ -28,10 +29,13 @@ import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.data.redis.listener.PatternTopic;
+import org.springframework.data.redis.listener.RedisMessageListenerContainer;
 import org.springframework.data.redis.serializer.StringRedisSerializer;
 import org.springframework.session.ExpiringSession;
 import org.springframework.session.SessionRepository;
 import org.springframework.session.data.redis.RedisOperationsSessionRepository;
+import org.springframework.session.data.redis.SessionMessageListener;
 import org.springframework.session.web.http.HttpSessionStrategy;
 import org.springframework.session.web.http.SessionRepositoryFilter;
 import org.springframework.util.ClassUtils;
@@ -55,6 +59,24 @@ public class RedisHttpSessionConfiguration implements ImportAware, BeanClassLoad
 
     private HttpSessionStrategy httpSessionStrategy;
 
+    @Autowired
+    private ApplicationEventPublisher eventPublisher;
+
+    @Bean
+    public RedisMessageListenerContainer redisMessageListenerContainer(
+            RedisConnectionFactory connectionFactory) {
+        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
+        container.setConnectionFactory(connectionFactory);
+        container.addMessageListener(redisSessionMessageListener(),
+                new PatternTopic("__keyspace@0__:spring:session:sessions:*"));
+        return container;
+    }
+
+    @Bean
+    public SessionMessageListener redisSessionMessageListener() {
+        return new SessionMessageListener(eventPublisher);
+    }
+
     @Bean
     public RedisTemplate<String,ExpiringSession> sessionRedisTemplate(RedisConnectionFactory connectionFactory) {
         RedisTemplate<String, ExpiringSession> template = new RedisTemplate<String, ExpiringSession>();

spring-session/src/main/java/org/springframework/session/events/SessionDestroyedEvent.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2002-2013 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.session.events;
+
+import org.springframework.context.ApplicationEvent;
+import org.springframework.session.Session;
+import org.springframework.session.SessionRepository;
+
+/**
+ * For {@link SessionRepository} implementations that support it, this event is
+ * fired when a {@link Session} is destroyed either explicitly or via
+ * expiration.
+ *
+ * @author Rob Winch
+ * @since 1.0
+ *
+ */
+@SuppressWarnings("serial")
+public class SessionDestroyedEvent extends ApplicationEvent {
+    private final String sessionId;
+
+    public SessionDestroyedEvent(Object source, String sessionId) {
+        super(source);
+        this.sessionId = sessionId;
+    }
+
+    public String getSessionId() {
+        return sessionId;
+    }
+}

spring-session/src/test/java/org/springframework/session/data/redis/SessionMessageListenerTests.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2002-2013 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.session.data.redis;
+
+import static org.fest.assertions.Assertions.assertThat;
+import static org.mockito.Mockito.*;
+
+import java.io.UnsupportedEncodingException;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.data.redis.connection.Message;
+import org.springframework.session.events.SessionDestroyedEvent;
+
+
+/**
+ *
+ * @author Rob Winch
+ *
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class SessionMessageListenerTests {
+    @Mock
+    ApplicationEventPublisher eventPublisher;
+
+    @Mock
+    Message message;
+
+    @Captor
+    ArgumentCaptor<SessionDestroyedEvent> event;
+
+    byte[] pattern;
+
+    SessionMessageListener listener;
+
+    @Before
+    public void setup() {
+        listener = new SessionMessageListener(eventPublisher);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void constructorNullEventPublisher() {
+        new SessionMessageListener(null);
+    }
+
+    @Test
+    public void onMessageNullBody() throws Exception {
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageDel() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSessionId()).isEqualTo("123");
+    }
+
+    @Test
+    public void onMessageSource() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSource()).isEqualTo(listener);
+    }
+
+    @Test
+    public void onMessageExpired() throws Exception {
+        mockMessage("expired","spring:sessions:session:543");
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(event.capture());
+        assertThat(event.getValue().getSessionId()).isEqualTo("543");
+    }
+
+    @Test
+    public void onMessageHset() throws Exception {
+        mockMessage("hset","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageRename() throws Exception {
+        mockMessage("rename","spring:sessions:session:123");
+
+        listener.onMessage(message, pattern);
+
+        verifyZeroInteractions(eventPublisher);
+    }
+
+    @Test
+    public void onMessageEventPublisherErrorCaught() throws Exception {
+        mockMessage("del","spring:sessions:session:123");
+        doThrow(new IllegalStateException("Test Exceptions are caught")).when(eventPublisher).publishEvent(any(ApplicationEvent.class));
+
+        listener.onMessage(message, pattern);
+
+        verify(eventPublisher).publishEvent(any(ApplicationEvent.class));
+    }
+
+    private void mockMessage(String body, String channel) throws UnsupportedEncodingException {
+        when(message.getBody()).thenReturn(bytes(body));
+        when(message.getChannel()).thenReturn(bytes(channel));
+    }
+
+    private static byte[] bytes(String s) throws UnsupportedEncodingException {
+        return s.getBytes("UTF-8");
+    }
+}