duke@435: /*
mikael@4153:  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #ifndef SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
stefank@2314: #define SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
stefank@2314: 
duke@435: // referencePolicy is used to determine when soft reference objects
duke@435: // should be cleared.
duke@435: 
duke@435: 
zgu@3900: class ReferencePolicy : public CHeapObj<mtGC> {
duke@435:  public:
johnc@3188:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188:     ShouldNotReachHere();
johnc@3188:     return true;
johnc@3188:   }
johnc@3188: 
ysr@888:   // Capture state (of-the-VM) information needed to evaluate the policy
ysr@892:   virtual void setup() { /* do nothing */ }
duke@435: };
duke@435: 
duke@435: class NeverClearPolicy : public ReferencePolicy {
duke@435:  public:
johnc@3188:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188:     return false;
johnc@3188:   }
duke@435: };
duke@435: 
duke@435: class AlwaysClearPolicy : public ReferencePolicy {
duke@435:  public:
johnc@3188:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
johnc@3188:     return true;
johnc@3188:   }
duke@435: };
duke@435: 
duke@435: class LRUCurrentHeapPolicy : public ReferencePolicy {
duke@435:  private:
duke@435:   jlong _max_interval;
duke@435: 
duke@435:  public:
duke@435:   LRUCurrentHeapPolicy();
duke@435: 
ysr@888:   // Capture state (of-the-VM) information needed to evaluate the policy
ysr@892:   void setup();
johnc@3188:   virtual bool should_clear_reference(oop p, jlong timestamp_clock);
duke@435: };
duke@435: 
duke@435: class LRUMaxHeapPolicy : public ReferencePolicy {
duke@435:  private:
duke@435:   jlong _max_interval;
duke@435: 
duke@435:  public:
duke@435:   LRUMaxHeapPolicy();
duke@435: 
ysr@888:   // Capture state (of-the-VM) information needed to evaluate the policy
ysr@892:   void setup();
johnc@3188:   virtual bool should_clear_reference(oop p, jlong timestamp_clock);
duke@435: };
stefank@2314: 
stefank@2314: #endif // SHARE_VM_MEMORY_REFERENCEPOLICY_HPP