1 /*
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  7  * published by the Free Software Foundation.
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 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).
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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);
 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   static 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