--- a/jdk/src/share/classes/java/security/ProtectionDomain.java	Mon Dec 07 21:16:41 2009 -0800
+++ b/jdk/src/share/classes/java/security/ProtectionDomain.java	Tue Dec 08 15:58:49 2009 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 1997-2009 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,9 +25,15 @@
 
 package java.security;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
-import java.util.ArrayList;
+import java.util.Map;
+import java.util.WeakHashMap;
+import sun.misc.JavaSecurityProtectionDomainAccess;
+import static sun.misc.JavaSecurityProtectionDomainAccess.ProtectionDomainCache;
+import sun.misc.SharedSecrets;
 import sun.security.util.Debug;
 import sun.security.util.SecurityConstants;
 
@@ -72,6 +78,11 @@
        or dynamic (via a policy refresh) */
     private boolean staticPermissions;
 
+    /*
+     * An object used as a key when the ProtectionDomain is stored in a Map.
+     */
+    final Key key = new Key();
+
     private static final Debug debug = Debug.getInstance("domain");
 
     /**
@@ -238,7 +249,7 @@
     /**
      * Convert a ProtectionDomain to a String.
      */
-    public String toString() {
+    @Override public String toString() {
         String pals = "<no principals>";
         if (principals != null && principals.length > 0) {
             StringBuilder palBuf = new StringBuilder("(principals ");
@@ -396,4 +407,29 @@
 
         return mergedPerms;
     }
+
+    /**
+     * Used for storing ProtectionDomains as keys in a Map.
+     */
+    final class Key {}
+
+    static {
+        SharedSecrets.setJavaSecurityProtectionDomainAccess(
+            new JavaSecurityProtectionDomainAccess() {
+                public ProtectionDomainCache getProtectionDomainCache() {
+                    return new ProtectionDomainCache() {
+                        private final Map<Key, PermissionCollection> map =
+                            Collections.synchronizedMap
+                                (new WeakHashMap<Key, PermissionCollection>());
+                        public void put(ProtectionDomain pd,
+                            PermissionCollection pc) {
+                            map.put((pd == null ? null : pd.key), pc);
+                        }
+                        public PermissionCollection get(ProtectionDomain pd) {
+                            return pd == null ? map.get(null) : map.get(pd.key);
+                        }
+                    };
+                }
+            });
+    }
 }