--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/referencePolicy.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2000, 2015, 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.
+ *
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_REFERENCEPOLICY_HPP
+#define SHARE_VM_GC_SHARED_REFERENCEPOLICY_HPP
+
+// referencePolicy is used to determine when soft reference objects
+// should be cleared.
+
+
+class ReferencePolicy : public CHeapObj<mtGC> {
+ public:
+  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
+    ShouldNotReachHere();
+    return true;
+  }
+
+  // Capture state (of-the-VM) information needed to evaluate the policy
+  virtual void setup() { /* do nothing */ }
+};
+
+class NeverClearPolicy : public ReferencePolicy {
+ public:
+  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
+    return false;
+  }
+};
+
+class AlwaysClearPolicy : public ReferencePolicy {
+ public:
+  virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
+    return true;
+  }
+};
+
+class LRUCurrentHeapPolicy : public ReferencePolicy {
+ private:
+  jlong _max_interval;
+
+ public:
+  LRUCurrentHeapPolicy();
+
+  // Capture state (of-the-VM) information needed to evaluate the policy
+  void setup();
+  virtual bool should_clear_reference(oop p, jlong timestamp_clock);
+};
+
+class LRUMaxHeapPolicy : public ReferencePolicy {
+ private:
+  jlong _max_interval;
+
+ public:
+  LRUMaxHeapPolicy();
+
+  // Capture state (of-the-VM) information needed to evaluate the policy
+  void setup();
+  virtual bool should_clear_reference(oop p, jlong timestamp_clock);
+};
+
+#endif // SHARE_VM_GC_SHARED_REFERENCEPOLICY_HPP