1 /* 2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_MEMORY_REFERENCEPOLICY_HPP 26 #define SHARE_VM_MEMORY_REFERENCEPOLICY_HPP 27 28 // referencePolicy is used to determine when soft reference objects 29 // should be cleared. 30 31 32 class ReferencePolicy : public CHeapObj { 33 public: 34 virtual bool should_clear_reference(oop p) { ShouldNotReachHere(); return true; } 35 // Capture state (of-the-VM) information needed to evaluate the policy 36 virtual void setup() { /* do nothing */ } 37 }; 38 39 class NeverClearPolicy : public ReferencePolicy { 40 public: 41 bool should_clear_reference(oop p) { return false; } 42 }; 43 44 class AlwaysClearPolicy : public ReferencePolicy { 45 public: 46 bool should_clear_reference(oop p) { return true; } 47 }; 48 49 class LRUCurrentHeapPolicy : public ReferencePolicy { 50 private: 51 jlong _max_interval; 52 53 public: 54 LRUCurrentHeapPolicy(); 55 56 // Capture state (of-the-VM) information needed to evaluate the policy 57 void setup(); 58 bool should_clear_reference(oop p); 59 }; 60 61 class LRUMaxHeapPolicy : public ReferencePolicy { 62 private: 63 jlong _max_interval; 64 65 public: 66 LRUMaxHeapPolicy(); 67 68 // Capture state (of-the-VM) information needed to evaluate the policy 69 void setup(); 70 bool should_clear_reference(oop p); 71 }; 72 73 #endif // SHARE_VM_MEMORY_REFERENCEPOLICY_HPP