fix(spring): implement thread safety for ServletContext resolution & lookup

Author: lincolnthree

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServiceEnricher.java

@@ -19,27 +19,25 @@
 import java.util.Collection;
 
 import javax.servlet.ServletContext;
-import javax.servlet.ServletContextEvent;
 
 import org.ocpsoft.common.spi.ServiceEnricher;
 import org.ocpsoft.logging.Logger;
-import org.ocpsoft.rewrite.servlet.spi.ContextListener;
 import org.springframework.web.context.support.SpringBeanAutowiringSupport;
 
 /**
  * {@link ServiceEnricher} implementation for Spring.
  * 
  * @author Christian Kaltepoth
  */
-public class SpringServiceEnricher implements ServiceEnricher, ContextListener
+public class SpringServiceEnricher implements ServiceEnricher
 {
 
    private final Logger log = Logger.getLogger(SpringServiceEnricher.class);
-   private static ServletContext context;
 
    @Override
    public <T> void enrich(final T service)
    {
+      ServletContext context = SpringServletContextLoader.getCurrentServletContext();
       if (context != null) {
          SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(service, context);
       }
@@ -58,22 +56,4 @@ public <T> Collection<T> produce(final Class<T> type)
       return new ArrayList<T>();
    }
 
-   @Override
-   public void contextInitialized(ServletContextEvent event)
-   {
-      context = event.getServletContext();
-   }
-
-   @Override
-   public void contextDestroyed(ServletContextEvent event)
-   {
-      context = null;
-   }
-
-   @Override
-   public int priority()
-   {
-      return 0;
-   }
-
 }

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServiceLocator.java

@@ -21,10 +21,8 @@
 import java.util.Set;
 
 import javax.servlet.ServletContext;
-import javax.servlet.ServletContextEvent;
 
 import org.ocpsoft.common.spi.ServiceLocator;
-import org.ocpsoft.rewrite.servlet.spi.ContextListener;
 import org.springframework.web.context.ContextLoader;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.WebApplicationContextUtils;
@@ -35,16 +33,15 @@
  * @author Christian Kaltepoth
  * @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
  */
-public class SpringServiceLocator implements ServiceLocator, ContextListener
+public class SpringServiceLocator implements ServiceLocator
 {
-   private static ServletContext servletContext;
-
    @Override
    @SuppressWarnings("unchecked")
    public <T> Collection<Class<T>> locate(Class<T> clazz)
    {
       Set<Class<T>> result = new LinkedHashSet<Class<T>>();
 
+      ServletContext servletContext = SpringServletContextLoader.getCurrentServletContext();
       WebApplicationContext applicationContext = null;
       if (servletContext != null) {
          applicationContext = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);
@@ -69,22 +66,4 @@ public <T> Collection<Class<T>> locate(Class<T> clazz)
       return result;
    }
 
-   @Override
-   public void contextInitialized(ServletContextEvent event)
-   {
-      servletContext = event.getServletContext();
-   }
-
-   @Override
-   public void contextDestroyed(ServletContextEvent event)
-   {
-      servletContext = null;
-   }
-
-   @Override
-   public int priority()
-   {
-      return 0;
-   }
-
 }

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServletContextLoader.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2011 <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
+ * 
+ * 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.ocpsoft.rewrite.spring;
+
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletRequestEvent;
+
+import org.ocpsoft.rewrite.servlet.spi.ContextListener;
+import org.ocpsoft.rewrite.servlet.spi.RequestListener;
+
+/**
+ * Thread-safe {@link ServletContext} loader implementation for Spring.
+ * 
+ * @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
+ */
+public class SpringServletContextLoader implements ContextListener, RequestListener
+{
+   private static final Map<ClassLoader, ServletContext> contextMap = new ConcurrentHashMap<>(1);
+
+   @Override
+   public void contextInitialized(ServletContextEvent event)
+   {
+      ServletContext servletContext = event.getServletContext();
+      contextMap.put(Thread.currentThread().getContextClassLoader(), servletContext);
+   }
+
+   @Override
+   public void contextDestroyed(ServletContextEvent event)
+   {
+      removeContext(event.getServletContext());
+   }
+
+   @Override
+   public void requestInitialized(ServletRequestEvent event)
+   {
+      ServletContext servletContext = event.getServletContext();
+      contextMap.put(Thread.currentThread().getContextClassLoader(), servletContext);
+   }
+
+   @Override
+   public void requestDestroyed(ServletRequestEvent event)
+   {
+      removeContext(event.getServletContext());
+
+   }
+
+   private static void removeContext(ServletContext context)
+   {
+      if (contextMap.containsValue(context)) {
+         for (Entry<ClassLoader, ServletContext> entry : contextMap.entrySet()) {
+            if (entry.getValue() == context) {
+               contextMap.remove(entry.getKey());
+            }
+         }
+      }
+   }
+
+   public static ServletContext getCurrentServletContext()
+   {
+      return contextMap.get(Thread.currentThread().getContextClassLoader());
+   }
+
+   @Override
+   public int priority()
+   {
+      return 0;
+   }
+
+}

integration-spring/src/main/resources/META-INF/services/org.ocpsoft.rewrite.servlet.spi.ContextListener

@@ -1,2 +1 @@
-org.ocpsoft.rewrite.spring.SpringServiceEnricher
-org.ocpsoft.rewrite.spring.SpringServiceLocator
+org.ocpsoft.rewrite.spring.SpringServletContextLoader