--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.naming/share/classes/com/sun/naming/internal/FactoryEnumeration.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 1999, 2011, Oracle and/or its affiliates. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.naming.internal;
+
+import java.util.List;
+import javax.naming.NamingException;
+
+/**
+  * The FactoryEnumeration is used for returning factory instances.
+  *
+  * @author Rosanna Lee
+  * @author Scott Seligman
+ */
+
+// no need to implement Enumeration since this is only for internal use
+public final class FactoryEnumeration {
+    // List<NamedWeakReference<Class | Object>>
+    private List<NamedWeakReference<Object>> factories;
+    private int posn = 0;
+    private ClassLoader loader;
+
+    /**
+     * Records the input list and uses it directly to satisfy
+     * hasMore()/next() requests. An alternative would have been to use
+     * an enumeration/iterator from the list, but we want to update the
+     * list so we keep the
+     * original list. The list initially contains Class objects.
+     * As each element is used, the Class object is replaced by an
+     * instance of the Class itself; eventually, the list contains
+     * only a list of factory instances and no more updates are required.
+     *
+     * <p> Both Class objects and factories are wrapped in weak
+     * references so as not to prevent GC of the class loader.  Each
+     * weak reference is tagged with the factory's class name so the
+     * class can be reloaded if the reference is cleared.
+     *
+     * @param factories A non-null list
+     * @param loader    The class loader of the list's contents
+     *
+     * This internal method is used with Thread Context Class Loader (TCCL),
+     * please don't expose this method as public.
+     */
+    FactoryEnumeration(List<NamedWeakReference<Object>> factories,
+                       ClassLoader loader) {
+        this.factories = factories;
+        this.loader = loader;
+    }
+
+    public Object next() throws NamingException {
+        synchronized (factories) {
+
+            NamedWeakReference<Object> ref = factories.get(posn++);
+            Object answer = ref.get();
+            if ((answer != null) && !(answer instanceof Class)) {
+                return answer;
+            }
+
+            String className = ref.getName();
+
+            try {
+                if (answer == null) {   // reload class if weak ref cleared
+                    Class<?> cls = Class.forName(className, true, loader);
+                    answer = cls;
+                }
+                // Instantiate Class to get factory
+                @SuppressWarnings("deprecation")
+                Object tmp = ((Class) answer).newInstance();
+                answer = tmp;
+                ref = new NamedWeakReference<>(answer, className);
+                factories.set(posn-1, ref);  // replace Class object or null
+                return answer;
+            } catch (ClassNotFoundException e) {
+                NamingException ne =
+                    new NamingException("No longer able to load " + className);
+                ne.setRootCause(e);
+                throw ne;
+            } catch (InstantiationException e) {
+                NamingException ne =
+                    new NamingException("Cannot instantiate " + answer);
+                ne.setRootCause(e);
+                throw ne;
+            } catch (IllegalAccessException e) {
+                NamingException ne = new NamingException("Cannot access " + answer);
+                ne.setRootCause(e);
+                throw ne;
+            }
+        }
+    }
+
+    public boolean hasMore() {
+        synchronized (factories) {
+            return posn < factories.size();
+        }
+    }
+}