[icedtea-web] RFC: Patch to fix PR895

[Deepak Bhole]

Hi,

Attached patch fixes PR895:
"IcedTea-Web searches for missing classes on each loadClass or findClass"

http://icedtea.classpath.org/bugzilla/show_bug.cgi?id=895

ChangeLog:
2012-03-09  Deepak Bhole <dbhole at redhat.com>

    * netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java: Added new
    notFoundClasses list.
    (loadClass): Record if a class is not found and on next call for that
    class, return immediately.
    (findClass): Same.

I think it should be applied to 1.1 and 1.2 because it prevents servers from
being hammered unnecessarily.

OK for 1.1, 1.2 and HEAD?

Thanks,
Deepak
-------------- next part --------------
diff -r d2aff3800f4f netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
--- a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java	Thu Mar 08 15:54:39 2012 +0100
+++ b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java	Fri Mar 09 17:16:33 2012 -0500
@@ -47,6 +47,7 @@
 import java.util.Set;
 import java.util.TreeSet;
 import java.util.Vector;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
@@ -178,6 +179,11 @@
     private int useCount = 0;
 
     /**
+     * Classes that are not found, so that findClass can skip them next time
+     */
+    CopyOnWriteArrayList<String> notFoundClasses = new CopyOnWriteArrayList<String>();
+
+    /**
      * Create a new JNLPClassLoader from the specified file.
      *
      * @param file the JNLP file
@@ -1315,6 +1321,10 @@
      */
     public synchronized Class<?> loadClass(String name) throws ClassNotFoundException {
 
+        // If we have searched before and not found it, don't bother again
+        if (notFoundClasses.contains(name))
+            throw new ClassNotFoundException(name);
+
         Class<?> result = findLoadedClassAll(name);
 
         // try parent classloader
@@ -1395,6 +1405,7 @@
         }
 
         if (result == null) {
+            notFoundClasses.add(name);
             throw new ClassNotFoundException(name);
         }
 
@@ -1490,6 +1501,11 @@
      * Find the class in this loader or any of its extension loaders.
      */
     protected Class findClass(String name) throws ClassNotFoundException {
+
+        // If we have searched before and not found it, don't bother again
+        if (notFoundClasses.contains(name))
+            throw new ClassNotFoundException(name);
+
         for (int i = 0; i < loaders.length; i++) {
             try {
                 if (loaders[i] == this)
@@ -1505,7 +1521,8 @@
         if (codeBaseLoader != null)
             return codeBaseLoader.findClass(name);
         
-        // All else failed. Throw CNFE
+        // All else failed. Record it and throw CNFE
+        notFoundClasses.add(name);
         throw new ClassNotFoundException(name);
     }