From 26a42bd2034a7ecb1e5bd0f0dfbd179a2185502a Mon Sep 17 00:00:00 2001
From: Stefan Bodewig <bodewig@apache.org>
Date: Thu, 3 Sep 2009 07:06:58 +0000
Subject: [PATCH] clean up classloaders if things go wrong as well

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@810790 13f79535-47bb-0310-9956-ffa450edef68
---
 .../ant/filters/util/ChainReaderHelper.java   | 25 +++++++++++++++----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/main/org/apache/tools/ant/filters/util/ChainReaderHelper.java b/src/main/org/apache/tools/ant/filters/util/ChainReaderHelper.java
index 068a5580b..41ba53b1f 100644
--- a/src/main/org/apache/tools/ant/filters/util/ChainReaderHelper.java
+++ b/src/main/org/apache/tools/ant/filters/util/ChainReaderHelper.java
@@ -24,6 +24,7 @@ import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Vector;
 import org.apache.tools.ant.AntClassLoader;
 import org.apache.tools.ant.BuildException;
@@ -138,6 +139,8 @@ public final class ChainReaderHelper {
         final int filtersCount = finalFilters.size();
 
         if (filtersCount > 0) {
+            boolean success = false;
+            try {
             for (int i = 0; i < filtersCount; i++) {
                 Object o = finalFilters.elementAt(i);
 
@@ -155,8 +158,8 @@ public final class ChainReaderHelper {
                             } else {
                                 AntClassLoader al
                                     = pro.createClassLoader(classpath);
-                                clazz = Class.forName(className, true, al);
                                 classLoadersToCleanUp.add(al);
+                                clazz = Class.forName(className, true, al);
                             }
                             if (clazz != null) {
                                 if (!FilterReader.class.isAssignableFrom(clazz)) {
@@ -208,16 +211,19 @@ public final class ChainReaderHelper {
                     setProjectOnObject(instream);
                 }
             }
+            success = true;
+            } finally {
+                if (!success && classLoadersToCleanUp.size() > 0) {
+                    cleanUpClassLoaders(classLoadersToCleanUp);
+                }
+            }
         }
         final Reader finalReader = instream;
         return classLoadersToCleanUp.size() == 0 ? finalReader
             : new FilterReader(finalReader) {
                     public void close() throws IOException {
                         FileUtils.close(in);
-                        for (Iterator it = classLoadersToCleanUp.iterator();
-                             it.hasNext(); ) {
-                            ((AntClassLoader) it.next()).cleanup();
-                        }
+                        cleanUpClassLoaders(classLoadersToCleanUp);
                     }
                     protected void finalize() throws Throwable {
                         try {
@@ -245,6 +251,15 @@ public final class ChainReaderHelper {
         project.setProjectReference(obj);
     }
 
+    /**
+     * Deregisters Classloaders from the project so GC can remove them later.
+     */
+    private static void cleanUpClassLoaders(List/*<AntClassLoader>*/ loaders) {
+        for (Iterator it = loaders.iterator(); it.hasNext(); ) {
+            ((AntClassLoader) it.next()).cleanup();
+        }
+    }
+
     /**
      * Read data from the reader and return the
      * contents as a string.