1 /* 2 * Copyright (c) 2001, 2012, 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 #include "precompiled.hpp" 26 #include "classfile/classLoaderData.hpp" 27 #include "memory/cardTableRS.hpp" 28 #include "memory/genRemSet.hpp" 29 30 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and 31 // enumerate ref fields that have been modified (since the last 32 // enumeration.) 33 34 uintx GenRemSet::max_alignment_constraint(Name nm) { 35 switch (nm) { 36 case GenRemSet::CardTable: 37 return CardTableRS::ct_max_alignment_constraint(); 38 default: 39 guarantee(false, "Unrecognized GenRemSet type."); 40 return (0); // Make Windows compiler happy 41 } 42 } 43 44 class HasAccumulatedModifiedOopsClosure : public KlassClosure { 45 bool _found; 46 public: 47 HasAccumulatedModifiedOopsClosure() : _found(false) {} 48 void do_klass(Klass* klass) { 49 if (_found) { 50 return; 51 } 52 53 if (klass->has_accumulated_modified_oops()) { 54 _found = true; 55 } 56 } 57 bool found() { 58 return _found; 59 } 60 }; 61 62 bool KlassRemSet::mod_union_is_clear() { 63 HasAccumulatedModifiedOopsClosure closure; 64 ClassLoaderDataGraph::classes_do(&closure); 65 66 return !closure.found(); 67 } 68 69 70 class ClearKlassModUnionClosure : public KlassClosure { 71 public: 72 void do_klass(Klass* klass) { 73 if (klass->has_accumulated_modified_oops()) { 74 klass->clear_accumulated_modified_oops(); 75 } 76 } 77 }; 78 79 void KlassRemSet::clear_mod_union() { 80 ClearKlassModUnionClosure closure; 81 ClassLoaderDataGraph::classes_do(&closure); 82 }