8193156: Need to backout fixes for JDK-8058547, JDK-8055753, JDK-8085903

Reviewed-by: mullan

src/share/classes/java/security/ProtectionDomain.java

 /*
- * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2017, 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
@@ -25,27 +25,21 @@
 
 package java.security;
 
-import java.lang.ref.Reference;
-import java.lang.ref.ReferenceQueue;
-import java.lang.ref.SoftReference;
-import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.WeakHashMap;
+import sun.misc.JavaSecurityAccess;
 import sun.misc.JavaSecurityProtectionDomainAccess;
 import static sun.misc.JavaSecurityProtectionDomainAccess.ProtectionDomainCache;
+import sun.misc.SharedSecrets;
 import sun.security.util.Debug;
 import sun.security.util.SecurityConstants;
-import sun.misc.JavaSecurityAccess;
-import sun.misc.SharedSecrets;
 
 /**
- *
- *<p>
- * This ProtectionDomain class encapsulates the characteristics of a domain,
+ * The ProtectionDomain class encapsulates the characteristics of a domain,
  * which encloses a set of classes whose instances are granted a set
  * of permissions when being executed on behalf of a given set of Principals.
  * <p>
@@ -460,14 +454,25 @@ public class ProtectionDomain {
     /**
      * Used for storing ProtectionDomains as keys in a Map.
      */
-    static final class Key {}
+    final class Key {}
 
     static {
         SharedSecrets.setJavaSecurityProtectionDomainAccess(
             new JavaSecurityProtectionDomainAccess() {
                 @Override
                 public ProtectionDomainCache getProtectionDomainCache() {
-                    return new PDCache();
+                    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);
+                        }
+                    };
                 }
 
                 @Override
@@ -476,119 +481,4 @@ public class ProtectionDomain {
                 }
             });
     }
-
-    /**
-     * A cache of ProtectionDomains and their Permissions.
-     *
-     * This class stores ProtectionDomains as weak keys in a ConcurrentHashMap
-     * with additional support for checking and removing weak keys that are no
-     * longer in use. There can be cases where the permission collection may
-     * have a chain of strong references back to the ProtectionDomain, which
-     * ordinarily would prevent the entry from being removed from the map. To
-     * address that, we wrap the permission collection in a SoftReference so
-     * that it can be reclaimed by the garbage collector due to memory demand.
-     */
-    private static class PDCache implements ProtectionDomainCache {
-        private final ConcurrentHashMap<WeakProtectionDomainKey,
-                                        SoftReference<PermissionCollection>>
-                                        pdMap = new ConcurrentHashMap<>();
-        private final ReferenceQueue<Key> queue = new ReferenceQueue<>();
-
-        @Override
-        public void put(ProtectionDomain pd, PermissionCollection pc) {
-            processQueue(queue, pdMap);
-            WeakProtectionDomainKey weakPd =
-                new WeakProtectionDomainKey(pd, queue);
-            pdMap.put(weakPd, new SoftReference<>(pc));
-        }
-
-        @Override
-        public PermissionCollection get(ProtectionDomain pd) {
-            processQueue(queue, pdMap);
-            WeakProtectionDomainKey weakPd = new WeakProtectionDomainKey(pd);
-            SoftReference<PermissionCollection> sr = pdMap.get(weakPd);
-            return (sr == null) ? null : sr.get();
-        }
-
-        /**
-         * Removes weak keys from the map that have been enqueued
-         * on the reference queue and are no longer in use.
-         */
-        private static void processQueue(ReferenceQueue<Key> queue,
-                                         ConcurrentHashMap<? extends
-                                         WeakReference<Key>, ?> pdMap) {
-            Reference<? extends Key> ref;
-            while ((ref = queue.poll()) != null) {
-                pdMap.remove(ref);
-            }
-        }
-    }
-
-    /**
-     * A weak key for a ProtectionDomain.
-     */
-    private static class WeakProtectionDomainKey extends WeakReference<Key> {
-        /**
-         * Saved value of the referent's identity hash code, to maintain
-         * a consistent hash code after the referent has been cleared
-         */
-        private final int hash;
-
-        /**
-         * A key representing a null ProtectionDomain.
-         */
-        private static final Key NULL_KEY = new Key();
-
-        /**
-         * Create a new WeakProtectionDomain with the specified domain and
-         * registered with a queue.
-         */
-        WeakProtectionDomainKey(ProtectionDomain pd, ReferenceQueue<Key> rq) {
-            this((pd == null ? NULL_KEY : pd.key), rq);
-        }
-
-        WeakProtectionDomainKey(ProtectionDomain pd) {
-            this(pd == null ? NULL_KEY : pd.key);
-        }
-
-        private WeakProtectionDomainKey(Key key, ReferenceQueue<Key> rq) {
-            super(key, rq);
-            hash = key.hashCode();
-        }
-
-        private WeakProtectionDomainKey(Key key) {
-            super(key);
-            hash = key.hashCode();
-        }
-
-        /**
-         * Returns the identity hash code of the original referent.
-         */
-        @Override
-        public int hashCode() {
-            return hash;
-        }
-
-        /**
-         * Returns true if the given object is an identical
-         * WeakProtectionDomainKey instance, or, if this object's referent
-         * has not been cleared and the given object is another
-         * WeakProtectionDomainKey instance with an identical non-null
-         * referent as this one.
-         */
-        @Override
-        public boolean equals(Object obj) {
-            if (obj == this) {
-                return true;
-            }
-
-            if (obj instanceof WeakProtectionDomainKey) {
-                Object referent = get();
-                return (referent != null) &&
-                       (referent == ((WeakProtectionDomainKey)obj).get());
-            } else {
-                return false;
-            }
-        }
-    }
 }