Refactor the TCCL processing to ClassLoaderContext

Handle the OSGi service un-registration gracefully

git-svn-id: http://svn.us.apache.org/repos/asf/tuscany@830852 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 299 insertions, 130 deletions

diff --git a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java
index 66df61996b..2317fbd475 100644
--- a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java
+++ b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/core/DefaultExtensionPointRegistry.java
@@ -41,7 +41,7 @@ import org.apache.tuscany.sca.extensibility.ServiceHelper;
  * @version $Rev$ $Date$
  */
 public class DefaultExtensionPointRegistry implements ExtensionPointRegistry {
-    private Map<Class<?>, Object> extensionPoints = new HashMap<Class<?>, Object>();
+    protected Map<Class<?>, Object> extensionPoints = new HashMap<Class<?>, Object>();
     private ServiceDiscovery discovery;
     /**
      * Constructs a new registry.
diff --git a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ClassLoaderContext.java b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ClassLoaderContext.java
new file mode 100644
index 0000000000..e6ccb22ed5
--- /dev/null
+++ b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ClassLoaderContext.java
@@ -0,0 +1,208 @@
+/*
+ * 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.tuscany.sca.extensibility;
+
+import java.security.PrivilegedAction;
+import java.security.PrivilegedActionException;
+import java.security.PrivilegedExceptionAction;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.apache.tuscany.sca.extensibility.impl.ClassLoaderDelegate;
+
+/**
+ * A utility that controls context class loaders
+ */
+public class ClassLoaderContext {
+    private ClassLoader classLoader;
+
+    /**
+     * Create a context with the parent classloader and a list of service types that can be discovered
+     * by the {@link ServiceDiscovery}
+     * @param parent
+     * @param discovery
+     * @param serviceTypes
+     */
+    public ClassLoaderContext(ClassLoader parent, ServiceDiscovery discovery, Class<?>... serviceTypes) {
+        this(parent, getClassLoaders(discovery, serviceTypes));
+    }
+
+    private ClassLoaderContext(ClassLoader parent, List<ClassLoader> delegates) {
+        List<ClassLoader> loaders = new ArrayList<ClassLoader>(delegates);
+        loaders.remove(parent);
+        if (delegates.isEmpty()) {
+            classLoader = parent;
+        } else {
+            classLoader = new ClassLoaderDelegate(parent, loaders);
+        }
+    }
+
+    /**
+     * Create a context that is visible to the parent classloader as well as the list of classloaders
+     * @param parent
+     * @param delegates
+     */
+    public ClassLoaderContext(ClassLoader parent, ClassLoader... delegates) {
+        this(parent, Arrays.asList(delegates));
+    }
+
+    /**
+     * Create a context with the parent classloader and a list of service types that can be discovered
+     * by the {@link ServiceDiscovery}
+     * @param parent
+     * @param discovery
+     * @param serviceTypes
+     */
+    public ClassLoaderContext(ClassLoader parent, ServiceDiscovery discovery, String... serviceTypes) {
+        this(parent, getClassLoaders(discovery, serviceTypes));
+    }
+
+    public <T> T doPrivileged(PrivilegedAction<T> action) {
+        ClassLoader tccl = Thread.currentThread().getContextClassLoader();
+        if (tccl != classLoader) {
+            Thread.currentThread().setContextClassLoader(classLoader);
+        }
+        try {
+            return action.run();
+        } finally {
+            if (tccl != classLoader) {
+                Thread.currentThread().setContextClassLoader(tccl);
+            }
+        }
+    }
+
+    public <T> T doPrivileged(PrivilegedExceptionAction<T> action) throws PrivilegedActionException {
+        ClassLoader tccl = Thread.currentThread().getContextClassLoader();
+        if (tccl != classLoader) {
+            Thread.currentThread().setContextClassLoader(classLoader);
+        }
+        try {
+            return action.run();
+        } catch (Exception e) {
+            throw new PrivilegedActionException(e);
+        } finally {
+            if (tccl != classLoader) {
+                Thread.currentThread().setContextClassLoader(tccl);
+            }
+        }
+    }
+
+    /**
+     * Set the thread context classloader (TCCL) to a classloader that delegates to a collection
+     * of classloaders 
+     * @param parent The parent classloader
+     * @param delegates A list of classloaders to try
+     * @return The existing TCCL 
+     */
+    public static ClassLoader setContextClassLoader(ClassLoader parent, ClassLoader... delegates) {
+        ClassLoaderContext context = new ClassLoaderContext(parent, delegates);
+        return context.setContextClassLoader();
+    }
+
+    /**
+     * Set the context classloader so that it can access the list of service providers
+     * @param parent The parent classloader
+     * @param serviceNames A list of service provider names
+     * @return The old TCCL if a new one is set, otherwise null
+     */
+    public static ClassLoader setContextClassLoader(ClassLoader parent, ServiceDiscovery discovery, String... serviceNames) {
+        ClassLoaderContext context = new ClassLoaderContext(parent, discovery, serviceNames);
+        return context.setContextClassLoader();
+    }
+
+    /**
+     * Set the context classloader so that it can access the list of service providers
+     * @param parent The parent classloader
+     * @param serviceNames A list of service provider names
+     * @return The old TCCL if a new one is set, otherwise null
+     */
+    public static ClassLoader setContextClassLoader(ClassLoader parent, ServiceDiscovery discovery, Class<?>... serviceTypes) {
+        ClassLoaderContext context = new ClassLoaderContext(parent, discovery, serviceTypes);
+        return context.setContextClassLoader();
+    }
+
+    public ClassLoader setContextClassLoader() {
+        ClassLoader tccl = Thread.currentThread().getContextClassLoader();
+        if (tccl != classLoader) {
+            Thread.currentThread().setContextClassLoader(classLoader);
+            return tccl;
+        } else {
+            return null;
+        }
+    }
+
+    private static ClassLoader getClassLoader(ServiceDiscovery discovery, String serviceProvider) {
+        try {
+            ServiceDeclaration sd = discovery.getServiceDeclaration(serviceProvider);
+            if (sd != null) {
+                return sd.loadClass().getClassLoader();
+            }
+        } catch (Exception e) {
+            // Ignore
+        }
+        return null;
+    }
+
+    private static List<ClassLoader> getClassLoaders(ServiceDiscovery discovery, String... serviceNames) {
+        List<ClassLoader> loaders = new ArrayList<ClassLoader>();
+        for (String sp : serviceNames) {
+            ClassLoader loader = getClassLoader(discovery, sp);
+            if (loader != null) {
+                if (!loaders.contains(loader)) {
+                    loaders.add(loader);
+                }
+            }
+        }
+        ClassLoader tccl = discovery.getContextClassLoader();
+        if (!loaders.contains(tccl)) {
+            loaders.add(tccl);
+        }
+        return loaders;
+    }
+
+    private static ClassLoader getClassLoader(ServiceDiscovery discovery, Class<?> serviceType) {
+        try {
+            ServiceDeclaration sd = discovery.getServiceDeclaration(serviceType);
+            if (sd != null) {
+                return sd.loadClass().getClassLoader();
+            }
+        } catch (Exception e) {
+            // Ignore
+        }
+        return null;
+    }
+
+    private static List<ClassLoader> getClassLoaders(ServiceDiscovery discovery, Class<?>... serviceTypes) {
+        List<ClassLoader> loaders = new ArrayList<ClassLoader>();
+        for (Class<?> serviceType : serviceTypes) {
+            ClassLoader classLoader = getClassLoader(discovery, serviceType);
+            if (classLoader != null && loaders.contains(classLoader)) {
+                loaders.add(classLoader);
+            }
+        }
+        ClassLoader tccl = discovery.getContextClassLoader();
+        if (!loaders.contains(tccl)) {
+            loaders.add(tccl);
+        }
+        return loaders;
+    }
+
+}
diff --git a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
index 1c03166eeb..b5f26c7a34 100644
--- a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
+++ b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
@@ -20,19 +20,16 @@
 package org.apache.tuscany.sca.extensibility;
 
 import java.io.IOException;
-import java.net.URL;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.Enumeration;
-import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
-import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import org.apache.tuscany.sca.extensibility.impl.ClassLoaderDelegate;
 import org.apache.tuscany.sca.extensibility.impl.LDAPFilter;
 
 /**
@@ -243,130 +240,5 @@ public final class ServiceDiscovery implements ServiceDiscoverer {
     public ClassLoader getContextClassLoader() {
         return discoverer.getContextClassLoader();
     }
-    
-    private static class ClassLoaderDelegate extends ClassLoader {
-        private final List<ClassLoader> classLoaders = new ArrayList<ClassLoader>();
-
-        /**
-         * @param parent The parent classloaders
-         * @param loaders A list of classloaders to be used to load classes or resources
-         */
-        public ClassLoaderDelegate(ClassLoader parent, Collection<ClassLoader> loaders) {
-            super(parent);
-            if (loaders != null) {
-                for (ClassLoader cl : loaders) {
-                    if (cl != null && cl != parent && !classLoaders.contains(cl)) {
-                        this.classLoaders.add(cl);
-                    }
-                }
-            }
-        }
-
-        @Override
-        protected Class<?> findClass(String className) throws ClassNotFoundException {
-            for (ClassLoader delegate : classLoaders) {
-                try {
-                    return delegate.loadClass(className);
-                } catch (ClassNotFoundException e) {
-                    continue;
-                }
-            }
-            throw new ClassNotFoundException(className);
-        }
-
-        @Override
-        protected URL findResource(String resName) {
-            for (ClassLoader delegate : classLoaders) {
-                URL url = delegate.getResource(resName);
-                if (url != null) {
-                    return url;
-                }
-            }
-            return null;
-        }
-
-        @Override
-        protected Enumeration<URL> findResources(String resName) throws IOException {
-            Set<URL> urlSet = new HashSet<URL>();
-            for (ClassLoader delegate : classLoaders) {
-                Enumeration<URL> urls = delegate.getResources(resName);
-                if (urls != null) {
-                    while (urls.hasMoreElements()) {
-                        urlSet.add(urls.nextElement());
-                    }
-                }
-            }
-            return Collections.enumeration(urlSet);
-        }
-    }
-
-    private ClassLoader getClassLoader(String serviceProvider) {
-        try {
-            ServiceDeclaration sd = getServiceDeclaration(serviceProvider);
-            if (sd != null) {
-                return sd.loadClass().getClassLoader();
-            }
-        } catch (Exception e) {
-            // Ignore
-        }
-        return null;
-    }
-    
-    /**
-     * Set the context classloader so that it can access the list of service providers
-     * @param parent The parent classloader
-     * @param serviceProviders A list of service provider names
-     * @return The old TCCL if a new one is set, otherwise null
-     */
-    public ClassLoader setContextClassLoader(ClassLoader parent, String... serviceProviders) {
-        List<ClassLoader> loaders = getClassLoaders(serviceProviders);
-        return setContextClassLoader(parent, loaders.toArray(new ClassLoader[loaders.size()]));
-    }
-
-    private List<ClassLoader> getClassLoaders(String... serviceProviders) {
-        List<ClassLoader> loaders = new ArrayList<ClassLoader>();
-        for (String sp : serviceProviders) {
-            ClassLoader loader = getClassLoader(sp);
-            if (loader != null) {
-                if (!loaders.contains(loader)) {
-                    loaders.add(loader);
-                }
-            }
-        }
-        return loaders;
-    }
-
-    /**
-     * Set the thread context classloader (TCCL) to a classloader that delegates to a collection
-     * of classloaders 
-     * @param parent The parent classloader
-     * @param delegates A list of classloaders to try
-     * @return The existing TCCL 
-     */
-    public ClassLoader setContextClassLoader(ClassLoader parent, ClassLoader... delegates) {
-        ClassLoader tccl = Thread.currentThread().getContextClassLoader();
-        List<ClassLoader> loaders = new ArrayList<ClassLoader>();
-        for (ClassLoader loader : delegates) {
-            if (loader != null && loader != tccl && loader != parent) {
-                if (!loaders.contains(loader)) {
-                    loaders.add(loader);
-                }
-            }
-        }
-        if (!loaders.isEmpty()) {
-            ClassLoader cl = getContextClassLoader();
-            if (cl != parent) {
-                loaders.add(cl);
-            }
-            if (tccl != parent) {
-                loaders.add(tccl);
-            }
-            ClassLoader newTccl = new ClassLoaderDelegate(parent, loaders);
-            Thread.currentThread().setContextClassLoader(newTccl);
-            return tccl;
-        } else {
-            return null;
-        }
-    }
 
 }
diff --git a/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/impl/ClassLoaderDelegate.java b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/impl/ClassLoaderDelegate.java
new file mode 100644
index 0000000000..d052d6b10f
--- /dev/null
+++ b/java/sca/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/impl/ClassLoaderDelegate.java
@@ -0,0 +1,89 @@
+/*
+ * 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.tuscany.sca.extensibility.impl;
+
+import java.io.IOException;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * A classloader that can delegate to a list of other classloaders
+ */
+public class ClassLoaderDelegate extends ClassLoader {
+    private final List<ClassLoader> classLoaders = new ArrayList<ClassLoader>();
+
+    /**
+     * @param parent The parent classloaders
+     * @param loaders A list of classloaders to be used to load classes or resources
+     */
+    public ClassLoaderDelegate(ClassLoader parent, Collection<ClassLoader> loaders) {
+        super(parent);
+        if (loaders != null) {
+            for (ClassLoader cl : loaders) {
+                if (cl != null && cl != parent && !classLoaders.contains(cl)) {
+                    this.classLoaders.add(cl);
+                }
+            }
+        }
+    }
+
+    @Override
+    protected Class<?> findClass(String className) throws ClassNotFoundException {
+        for (ClassLoader delegate : classLoaders) {
+            try {
+                return delegate.loadClass(className);
+            } catch (ClassNotFoundException e) {
+                continue;
+            }
+        }
+        throw new ClassNotFoundException(className);
+    }
+
+    @Override
+    protected URL findResource(String resName) {
+        for (ClassLoader delegate : classLoaders) {
+            URL url = delegate.getResource(resName);
+            if (url != null) {
+                return url;
+            }
+        }
+        return null;
+    }
+
+    @Override
+    protected Enumeration<URL> findResources(String resName) throws IOException {
+        Set<URL> urlSet = new HashSet<URL>();
+        for (ClassLoader delegate : classLoaders) {
+            Enumeration<URL> urls = delegate.getResources(resName);
+            if (urls != null) {
+                while (urls.hasMoreElements()) {
+                    urlSet.add(urls.nextElement());
+                }
+            }
+        }
+        return Collections.enumeration(urlSet);
+    }
+}