1 /* 2 * Copyright (c) 2000, 2015, 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_GC_SHARED_REFERENCEPOLICY_HPP 26 #define SHARE_VM_GC_SHARED_REFERENCEPOLICY_HPP 27 28 #include "oops/oopsHierarchy.hpp" 29 30 // referencePolicy is used to determine when soft reference objects 31 // should be cleared. 32 33 34 class ReferencePolicy : public CHeapObj<mtGC> { 35 public: 36 virtual bool should_clear_reference(oop p, jlong timestamp_clock) { 37 ShouldNotReachHere(); 38 return true; 39 } 40 41 // Capture state (of-the-VM) information needed to evaluate the policy 42 virtual void setup() { /* do nothing */ } 43 }; 44 45 class NeverClearPolicy : public ReferencePolicy { 46 public: 47 virtual bool should_clear_reference(oop p, jlong timestamp_clock) { 48 return false; 49 } 50 }; 51 52 class AlwaysClearPolicy : public ReferencePolicy { 53 public: 54 virtual bool should_clear_reference(oop p, jlong timestamp_clock) { 55 return true; 56 } 57 }; 58 59 class LRUCurrentHeapPolicy : public ReferencePolicy { 60 private: 61 jlong _max_interval; 62 63 public: 64 LRUCurrentHeapPolicy(); 65 66 // Capture state (of-the-VM) information needed to evaluate the policy 67 void setup(); 68 virtual bool should_clear_reference(oop p, jlong timestamp_clock); 69 }; 70 71 class LRUMaxHeapPolicy : public ReferencePolicy { 72 private: 73 jlong _max_interval; 74 75 public: 76 LRUMaxHeapPolicy(); 77 78 // Capture state (of-the-VM) information needed to evaluate the policy 79 void setup(); 80 virtual bool should_clear_reference(oop p, jlong timestamp_clock); 81 }; 82 83 #endif // SHARE_VM_GC_SHARED_REFERENCEPOLICY_HPP