From 8e08a8226a752024187d7cefe481a4725f4bcdf1 Mon Sep 17 00:00:00 2001
From: Remi Vankeisbelck <remi@rvkb.com>
Date: Wed, 27 Jan 2016 14:47:55 +0100
Subject: [PATCH] #37 : cleanup, cache Async implementation class ctor to avoid
 looking it up too often

---
 .../stripes/controller/AsyncResolution.java   | 43 +++++++++++++------
 .../stripes/controller/DispatcherServlet.java |  1 -
 2 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/stripes/src/main/java/net/sourceforge/stripes/controller/AsyncResolution.java b/stripes/src/main/java/net/sourceforge/stripes/controller/AsyncResolution.java
index dd9842209..ec8f90f24 100644
--- a/stripes/src/main/java/net/sourceforge/stripes/controller/AsyncResolution.java
+++ b/stripes/src/main/java/net/sourceforge/stripes/controller/AsyncResolution.java
@@ -2,6 +2,8 @@
 
 import net.sourceforge.stripes.action.ActionBean;
 import net.sourceforge.stripes.action.Resolution;
+import net.sourceforge.stripes.exception.StripesRuntimeException;
+import net.sourceforge.stripes.util.Log;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -11,12 +13,36 @@
 
 public abstract class AsyncResolution implements Resolution {
 
+	private static final Log log = Log.getInstance(AsyncResolution.class);
+
 	private static final String REQ_ATTR_NAME = "__Stripes_Async_Resolution";
 	private final HttpServletRequest request;
 	private final HttpServletResponse response;
 	private final ActionBean bean;
 	private final Method handler;
 
+	private static Constructor<?> ctor = null;
+
+	static {
+		try {
+			HttpServletRequest.class.getMethod("startAsync");
+			Class<?> impl = Class.forName("net.sourceforge.stripes.controller.AsyncResolutionServlet3");
+			ctor = impl.getDeclaredConstructor(
+				HttpServletRequest.class,
+				HttpServletResponse.class,
+				ActionBean.class,
+				Method.class);
+		} catch (NoSuchMethodException e) {
+			// servlet3 not available
+			log.info("Container is not using Servlet3 : Async event handlers will throw runtime exceptions.");
+		} catch (Exception e) {
+			// should not happen unless we break internals (bad refactor etc).
+			log.error("Exception while initializing AsyncResolution implementation class.", e);
+			throw new RuntimeException(e);
+		}
+
+	}
+
 	private Runnable cleanupCallback;
 	private long timeout;
 
@@ -67,23 +93,12 @@ public void execute(HttpServletRequest request, HttpServletResponse response) th
 	public abstract void setTimeout(long timeout);
 
 	public static AsyncResolution newInstance(HttpServletRequest request, HttpServletResponse response, ActionBean bean, Method handler) {
-		// check wether or not we're using servlet3
+		if (ctor == null) {
+			throw new StripesRuntimeException("Async events are not available in your container (requires Servlet3+).");
+		}
 		try {
-			HttpServletRequest.class.getMethod("startAsync");
-			Class<?> impl = Class.forName("net.sourceforge.stripes.controller.AsyncResolutionServlet3");
-			Constructor<?> ctor = impl.getDeclaredConstructor(
-				HttpServletRequest.class,
-				HttpServletResponse.class,
-				ActionBean.class,
-				Method.class);
 			Object o = ctor.newInstance(request, response, bean, handler);
 			return (AsyncResolution)o;
-		} catch (NoSuchMethodException e) {
-			// not using servlet 3, throw exception for the moment
-			throw new UnsupportedOperationException("Async action beans require Servlet3+");
-		} catch (ClassNotFoundException e) {
-			// should never happen unless bad refactor
-			throw new RuntimeException(e);
 		} catch (IllegalAccessException e) {
 			throw new RuntimeException(e);
 		} catch (InstantiationException e) {
diff --git a/stripes/src/main/java/net/sourceforge/stripes/controller/DispatcherServlet.java b/stripes/src/main/java/net/sourceforge/stripes/controller/DispatcherServlet.java
index 193c88802..674c0c4d1 100644
--- a/stripes/src/main/java/net/sourceforge/stripes/controller/DispatcherServlet.java
+++ b/stripes/src/main/java/net/sourceforge/stripes/controller/DispatcherServlet.java
@@ -44,7 +44,6 @@
  *
  * @author Tim Fennell
  */
-//@WebServlet(asyncSupported = true)
 public class DispatcherServlet extends HttpServlet {
 	private static final long serialVersionUID = 1L;