1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_OOPS_INSTANCEREFKLASS_HPP
26 #define SHARE_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 KlassKind Kind = InstanceRefKlassKind;
54
55 private:
56 InstanceRefKlass(const ClassFileParser& parser) : InstanceKlass(parser, Kind) {}
57
58 public:
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_discovered(oop obj, OopClosureType* closure, Contains& contains);
102
103 template <typename T, class OopClosureType>
104 static bool try_discover(oop obj, ReferenceType type, OopClosureType* closure);
105
106 // Do discovery while handling InstanceRefKlasses. Reference discovery
107 // is only done if the closure provides a ReferenceProcessor.
108 template <typename T, class OopClosureType, class Contains>
109 static void oop_oop_iterate_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains);
110
111 // Used for a special case in G1 where the closure needs to be applied
112 // to the discovered field. Reference discovery is also done if the
113 // closure provides a ReferenceProcessor.
114 template <typename T, class OopClosureType, class Contains>
115 static void oop_oop_iterate_discovered_and_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains);
116
117 // Apply the closure to all fields. No reference discovery is done.
118 template <typename T, class OopClosureType, class Contains>
119 static void oop_oop_iterate_fields(oop obj, OopClosureType* closure, Contains& contains);
120
121 // Apply the closure to all fields, except the referent field. No reference discovery is done.
122 template <typename T, class OopClosureType, class Contains>
123 static void oop_oop_iterate_fields_except_referent(oop obj, OopClosureType* closure, Contains& contains);
124
125 template <typename T>
126 void trace_reference_gc(const char *s, oop obj) NOT_DEBUG_RETURN;
127
128 public:
129 // Update non-static oop maps so 'referent', 'nextPending' and
130 // 'discovered' will look like non-oops
131 static void update_nonstatic_oop_maps(Klass* k);
132
133 public:
134 // Verification
135 void oop_verify_on(oop obj, outputStream* st);
136 };
137
138 #endif // SHARE_OOPS_INSTANCEREFKLASS_HPP