Issue #5162 CDI embedded integration improvements (#5177)

* Issue #5162 CDI embedded integration improvements

Clean up CDI integration and documentation to better support embedded usage.
 + made listener public
 + added utility class for SCIs

* Issue #5162 CDI embedded integration improvements

Clean up CDI integration and documentation to better support embedded usage.
 + moved EmbeddedWeldTest to jetty-embedded

* fix javadoc

Signed-off-by: Greg Wilkins <gregw@webtide.com>

* Issue #5162 CDI embedded integration improvements

ventilated text

* fix test pom

Signed-off-by: Greg Wilkins <gregw@webtide.com>

* Fixed javadoc

* Fixed javadoc

* Issue #5162 CDI embedded integration improvements

Moved tests to jetty-cdi to avoid consequences to other tests in embedded

* trailing new line

Signed-off-by: Greg Wilkins <gregw@webtide.com>

* updates from review

Signed-off-by: Greg Wilkins <gregw@webtide.com>

* Feedback from review

jetty-cdi/pom.xml

@@ -32,6 +32,12 @@
       <version>${project.version}</version>
       <scope>compile</scope>
     </dependency>
+    <dependency>
+      <groupId>org.jboss.weld.servlet</groupId>
+      <artifactId>weld-servlet-core</artifactId>
+      <version>${weld.version}</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
   <build>
     <plugins>

jetty-cdi/src/main/java/org/eclipse/jetty/cdi/CdiDecoratingListener.java

@@ -24,13 +24,14 @@
 /**
  * A DecoratingListener that listens for "org.eclipse.jetty.cdi.decorator"
  */
-class CdiDecoratingListener extends DecoratingListener
+public class CdiDecoratingListener extends DecoratingListener
 {
     public static final String MODE = "CdiDecoratingListener";
     public static final String ATTRIBUTE = "org.eclipse.jetty.cdi.decorator";
 
     public CdiDecoratingListener(ServletContextHandler contextHandler)
     {
         super(contextHandler, ATTRIBUTE);
+        contextHandler.setAttribute(CdiServletContainerInitializer.CDI_INTEGRATION_ATTRIBUTE, MODE);
     }
 }

jetty-cdi/src/main/java/org/eclipse/jetty/cdi/CdiServletContainerInitializer.java

@@ -86,8 +86,6 @@ public void onStartup(Set<Class<?>> c, ServletContext ctx)
                 default:
                     throw new IllegalStateException(mode);
             }
-
-            context.setAttribute(CDI_INTEGRATION_ATTRIBUTE, mode);
             LOG.info(mode + " enabled in " + ctx);
         }
         catch (UnsupportedOperationException | ClassNotFoundException e)

jetty-cdi/src/main/java/org/eclipse/jetty/cdi/CdiSpiDecorator.java

@@ -21,8 +21,12 @@
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import org.eclipse.jetty.servlet.ServletContextHandler;
 import org.eclipse.jetty.util.Decorator;
@@ -61,11 +65,15 @@ public class CdiSpiDecorator implements Decorator
     private final MethodHandle _inject;
     private final MethodHandle _dispose;
     private final MethodHandle _release;
+    private final Set<String> _undecorated = new HashSet<>(Collections.singletonList("org.jboss.weld.environment.servlet.Listener"));
 
     public CdiSpiDecorator(ServletContextHandler context) throws UnsupportedOperationException
     {
         _context = context;
+        context.setAttribute(CdiServletContainerInitializer.CDI_INTEGRATION_ATTRIBUTE, MODE);
         ClassLoader classLoader = _context.getClassLoader();
+        if (classLoader == null)
+            classLoader = this.getClass().getClassLoader();
 
         try
         {
@@ -92,6 +100,54 @@ public CdiSpiDecorator(ServletContextHandler context) throws UnsupportedOperatio
         }
     }
 
+    /**
+     * Test if a class can be decorated.
+     * The default implementation checks the set from  {@link #getUndecoratable()}
+     * on the class and all it's super classes.
+     * @param clazz The class to check
+     * @return True if the class and all it's super classes can be decorated
+     */
+    protected boolean isDecoratable(Class<?> clazz)
+    {
+        if (Object.class == clazz)
+            return true;
+        if (getUndecoratable().contains(clazz.getName()))
+            return false;
+        return isDecoratable(clazz.getSuperclass());
+    }
+
+    /**
+     * Get the set of classes that will not be decorated. The default set includes the listener from Weld that will itself
+     * setup decoration.
+     * @return The modifiable set of class names that will not be decorated (ie {@link #isDecoratable(Class)} will return false.
+     * @see #isDecoratable(Class)
+     */
+    public Set<String> getUndecoratable()
+    {
+        return _undecorated;
+    }
+
+    /**
+     * @param classnames The set of class names that will not be decorated.
+     * @see #isDecoratable(Class)
+     */
+    public void setUndecoratable(Set<String> classnames)
+    {
+        _undecorated.clear();
+        if (classnames != null)
+            _undecorated.addAll(classnames);
+    }
+
+    /**
+     * @param classname A class name that will be added to the undecoratable classes set.
+     * @see #getUndecoratable()
+     * @see #isDecoratable(Class)
+     */
+    public void addUndecoratable(String... classname)
+    {
+        _undecorated.addAll(Arrays.asList());
+    }
+
     /**
      * Decorate an object.
      * <p>The signature of this method must match what is introspected for by the
@@ -108,7 +164,8 @@ public <T> T decorate(T o)
             if (LOG.isDebugEnabled())
                 LOG.debug("decorate {} in {}", o, _context);
 
-            _decorated.put(o, new Decorated(o));
+            if (isDecoratable(o.getClass()))
+                _decorated.put(o, new Decorated(o));
         }
         catch (Throwable th)
         {