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// An InstanceRefKlass is a specialized InstanceKlass for Java // classes that are subclasses of java/lang/ref/Reference. // // These classes are used to implement soft/weak/final/phantom // references and finalization, and need special treatment by the // garbage collector. // // During GC discovered reference objects are added (chained) to one // of the four lists below, depending on the type of reference. // The linked occurs through the next field in class java/lang/ref/Reference. // // Afterwards, the discovered references are processed in decreasing // order of reachability. Reference objects eligible for notification // are linked to the static pending_list in class java/lang/ref/Reference, // and the pending list lock object in the same class is notified.
class InstanceRefKlass: public InstanceKlass { friendclass InstanceKlass; public: staticconst KlassKind Kind = InstanceRefKlassKind;
public:
InstanceRefKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
// Oop fields (and metadata) iterators // // The InstanceRefKlass iterators also support reference processing.
// Forward iteration // Iterate over all oop fields and metadata. template <typename T, class OopClosureType> inlinevoid oop_oop_iterate(oop obj, OopClosureType* closure);
// Reverse iteration // Iterate over all oop fields and metadata. template <typename T, class OopClosureType> inlinevoid oop_oop_iterate_reverse(oop obj, OopClosureType* closure);
// Bounded range iteration // Iterate over all oop fields and metadata. template <typename T, class OopClosureType> inlinevoid oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr);
private:
// Reference processing part of the iterators.
template <typename T, class OopClosureType, class Contains> inlinevoid oop_oop_iterate_ref_processing(oop obj, OopClosureType* closure, Contains& contains);
// Only perform reference processing if the referent object is within mr. template <typename T, class OopClosureType> inlinevoid oop_oop_iterate_ref_processing_bounded(oop obj, OopClosureType* closure, MemRegion mr);
// Building blocks for specialized handling. template <typename T, class OopClosureType, class Contains> staticvoid do_referent(oop obj, OopClosureType* closure, Contains& contains);
template <typename T, class OopClosureType, class Contains> staticvoid do_discovered(oop obj, OopClosureType* closure, Contains& contains);
// Do discovery while handling InstanceRefKlasses. Reference discovery // is only done if the closure provides a ReferenceProcessor. template <typename T, class OopClosureType, class Contains> staticvoid oop_oop_iterate_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains);
// Used for a special case in G1 where the closure needs to be applied // to the discovered field. Reference discovery is also done if the // closure provides a ReferenceProcessor. template <typename T, class OopClosureType, class Contains> staticvoid oop_oop_iterate_discovered_and_discovery(oop obj, ReferenceType type, OopClosureType* closure, Contains& contains);
// Apply the closure to all fields. No reference discovery is done. template <typename T, class OopClosureType, class Contains> staticvoid oop_oop_iterate_fields(oop obj, OopClosureType* closure, Contains& contains);
// Apply the closure to all fields, except the referent field. No reference discovery is done. template <typename T, class OopClosureType, class Contains> staticvoid oop_oop_iterate_fields_except_referent(oop obj, OopClosureType* closure, Contains& contains);
public: // Update non-static oop maps so 'referent', 'nextPending' and // 'discovered' will look like non-oops staticvoid update_nonstatic_oop_maps(Klass* k);
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