aoqi@0: /*
aoqi@0:  * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
aoqi@0: #define SHARE_VM_MEMORY_REFERENCEPOLICY_HPP
aoqi@0: 
aoqi@0: // referencePolicy is used to determine when soft reference objects
aoqi@0: // should be cleared.
aoqi@0: 
aoqi@0: 
aoqi@0: class ReferencePolicy : public CHeapObj<mtGC> {
aoqi@0:  public:
aoqi@0:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
aoqi@0:     ShouldNotReachHere();
aoqi@0:     return true;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Capture state (of-the-VM) information needed to evaluate the policy
aoqi@0:   virtual void setup() { /* do nothing */ }
aoqi@0: };
aoqi@0: 
aoqi@0: class NeverClearPolicy : public ReferencePolicy {
aoqi@0:  public:
aoqi@0:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
aoqi@0:     return false;
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: class AlwaysClearPolicy : public ReferencePolicy {
aoqi@0:  public:
aoqi@0:   virtual bool should_clear_reference(oop p, jlong timestamp_clock) {
aoqi@0:     return true;
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: class LRUCurrentHeapPolicy : public ReferencePolicy {
aoqi@0:  private:
aoqi@0:   jlong _max_interval;
aoqi@0: 
aoqi@0:  public:
aoqi@0:   LRUCurrentHeapPolicy();
aoqi@0: 
aoqi@0:   // Capture state (of-the-VM) information needed to evaluate the policy
aoqi@0:   void setup();
aoqi@0:   virtual bool should_clear_reference(oop p, jlong timestamp_clock);
aoqi@0: };
aoqi@0: 
aoqi@0: class LRUMaxHeapPolicy : public ReferencePolicy {
aoqi@0:  private:
aoqi@0:   jlong _max_interval;
aoqi@0: 
aoqi@0:  public:
aoqi@0:   LRUMaxHeapPolicy();
aoqi@0: 
aoqi@0:   // Capture state (of-the-VM) information needed to evaluate the policy
aoqi@0:   void setup();
aoqi@0:   virtual bool should_clear_reference(oop p, jlong timestamp_clock);
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_MEMORY_REFERENCEPOLICY_HPP