duke@435: /*
duke@435:  * Copyright 2000 Sun Microsystems, Inc.  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:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // referencePolicy is used to determine when soft reference objects
duke@435: // should be cleared.
duke@435: 
duke@435: 
duke@435: class ReferencePolicy : public ResourceObj {
duke@435:  public:
duke@435:   virtual bool should_clear_reference(oop p)       { ShouldNotReachHere(); return true; }
duke@435: };
duke@435: 
duke@435: class NeverClearPolicy : public ReferencePolicy {
duke@435:  public:
duke@435:   bool should_clear_reference(oop p) { return false; }
duke@435: };
duke@435: 
duke@435: class AlwaysClearPolicy : public ReferencePolicy {
duke@435:  public:
duke@435:   bool should_clear_reference(oop p) { return true; }
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: 
duke@435:   bool should_clear_reference(oop p);
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: 
duke@435:   bool should_clear_reference(oop p);
duke@435: };