1 /* 2 * Copyright (c) 1997, 2018, 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_OOPS_INSTANCEREFKLASS_HPP 26 #define SHARE_VM_OOPS_INSTANCEREFKLASS_HPP 27 28 #include "oops/instanceKlass.hpp" 29 #include "utilities/macros.hpp" 30 31 class ClassFileParser; 32 33 // An InstanceRefKlass is a specialized InstanceKlass for Java 34 // classes that are subclasses of java/lang/ref/Reference. 35 // 36 // These classes are used to implement soft/weak/final/phantom 37 // references and finalization, and need special treatment by the 38 // garbage collector. 39 // 40 // During GC discovered reference objects are added (chained) to one 41 // of the four lists below, depending on the type of reference. 42 // The linked occurs through the next field in class java/lang/ref/Reference. 43 // 44 // Afterwards, the discovered references are processed in decreasing 45 // order of reachability. Reference objects eligible for notification 46 // are linked to the static pending_list in class java/lang/ref/Reference, 47 // and the pending list lock object in the same class is notified. 48 49 50 class InstanceRefKlass: public InstanceKlass { 51 friend class InstanceKlass; 52 public: 53 static const KlassID ID = InstanceRefKlassID; 54 55 private: InstanceRefKlass(const ClassFileParser & parser)56 InstanceRefKlass(const ClassFileParser& parser) : InstanceKlass(parser, InstanceKlass::_misc_kind_reference, ID) {} 57 58 public: InstanceRefKlass()59 InstanceRefKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); } 60 61 // Oop fields (and metadata) iterators 62 // 63 // The InstanceRefKlass iterators also support reference processing. 64 65 66 // Forward iteration 67 // Iterate over all oop fields and metadata. 68 template <typename T, class OopClosureType> 69 inline void oop_oop_iterate(oop obj, OopClosureType* closure); 70 71 // Reverse iteration 72 // Iterate over all oop fields and metadata. 73 template <typename T, class OopClosureType> 74 inline void oop_oop_iterate_reverse(oop obj, OopClosureType* closure); 75 76 // Bounded range iteration 77 // Iterate over all oop fields and metadata. 78 template <typename T, class OopClosureType> 79 inline void oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr); 80 81 private: 82 83 // Reference processing part of the iterators. 84 85 template <typename T, class OopClosureType, class Contains> 86 inline void oop_oop_iterate_ref_processing(oop obj, OopClosureType* closure, Contains& contains); 87 88 // Only perform reference processing if the referent object is within mr. 89 template <typename T, class OopClosureType> 90 inline void oop_oop_iterate_ref_processing_bounded(oop obj, OopClosureType* closure, MemRegion mr); 91 92 // Reference processing 93 template <typename T, class OopClosureType> 94 inline void oop_oop_iterate_ref_processing(oop obj, OopClosureType* closure); 95 96 // Building blocks for specialized handling. 97 template <typename T, class OopClosureType, class Contains> 98 static void do_referent(oop obj, OopClosureType* closure, Contains& contains); 99 100 template <typename T, class OopClosureType, class Contains> 101 static void do_next(oop obj, OopClosureType* closure, Contains& contains); 102 103 template <typename T, class OopClosureType, class Contains> 104 static void do_discovered(oop obj, OopClosureType* closure, Contains& contains); 105 106 template <typename T, class OopClosureType> 107 static bool try_discover(oop obj, ReferenceType type, OopClosureType* closure); 108 109 // Do discovery while handling InstanceRefKlasses. Reference discovery 110 // is only done if the closure provides a ReferenceProcessor. 111 template <typename T, class OopClosureType, class Contains> 112 static void oop_oop_iterate_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains); 113 114 // Used for a special case in G1 where the closure needs to be applied 115 // to the discovered field. Reference discovery is also done if the 116 // closure provides a ReferenceProcessor. 117 template <typename T, class OopClosureType, class Contains> 118 static void oop_oop_iterate_discovered_and_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains); 119 120 // Apply the closure to all fields. No reference discovery is done. 121 template <typename T, class OopClosureType, class Contains> 122 static void oop_oop_iterate_fields(oop obj, OopClosureType* closure, Contains& contains); 123 124 // Apply the closure to all fields, except the referent field. No reference discovery is done. 125 template <typename T, class OopClosureType, class Contains> 126 static void oop_oop_iterate_fields_except_referent(oop obj, OopClosureType* closure, Contains& contains); 127 128 template <typename T> 129 static void trace_reference_gc(const char *s, oop obj) NOT_DEBUG_RETURN; 130 131 public: 132 // Update non-static oop maps so 'referent', 'nextPending' and 133 // 'discovered' will look like non-oops 134 static void update_nonstatic_oop_maps(Klass* k); 135 136 public: 137 // Verification 138 void oop_verify_on(oop obj, outputStream* st); 139 }; 140 141 #endif // SHARE_VM_OOPS_INSTANCEREFKLASS_HPP 142