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src/hotspot/share/oops/weakHandle.hpp

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  22  *
  23  */
  24 
  25 #ifndef SHARE_OOPS_WEAKHANDLE_HPP
  26 #define SHARE_OOPS_WEAKHANDLE_HPP
  27 
  28 #include "oops/oop.hpp"
  29 #include "runtime/handles.hpp"
  30 
  31 class outputStream;
  32 class OopStorage;
  33 
  34 // A WeakHandle is a pointer to an oop that is stored in an OopStorage that is
  35 // processed weakly by GC.  The runtime structures that point to the oop must
  36 // either peek or resolve the oop, the latter will keep the oop alive for
  37 // the GC cycle.  The runtime structures that reference the oop must test
  38 // if the value is NULL.  If it is NULL, it has been cleaned out by GC.
  39 // This is the vm version of jweak but has different GC lifetimes and policies,
  40 // depending on the type.
  41 
  42 enum WeakHandleType { vm_class_loader_data, vm_string_table_data, vm_resolved_method_table_data };
  43 
  44 template <WeakHandleType T>
  45 class WeakHandle {
  46  public:
  47  private:
  48   oop* _obj;
  49 
  50   WeakHandle(oop* w) : _obj(w) {}
  51   static OopStorage* get_storage();
  52  public:
  53   WeakHandle() : _obj(NULL) {} // needed for init
  54 
  55   static WeakHandle create(Handle obj);

  56   inline oop resolve() const;
  57   inline oop peek() const;
  58   void release() const;
  59   bool is_null() const { return _obj == NULL; }
  60 
  61   void replace(oop with_obj);

  62 
  63   void print() const;
  64   void print_on(outputStream* st) const;
  65 };
  66 
  67 #endif // SHARE_OOPS_WEAKHANDLE_HPP


  22  *
  23  */
  24 
  25 #ifndef SHARE_OOPS_WEAKHANDLE_HPP
  26 #define SHARE_OOPS_WEAKHANDLE_HPP
  27 
  28 #include "oops/oop.hpp"
  29 #include "runtime/handles.hpp"
  30 
  31 class outputStream;
  32 class OopStorage;
  33 
  34 // A WeakHandle is a pointer to an oop that is stored in an OopStorage that is
  35 // processed weakly by GC.  The runtime structures that point to the oop must
  36 // either peek or resolve the oop, the latter will keep the oop alive for
  37 // the GC cycle.  The runtime structures that reference the oop must test
  38 // if the value is NULL.  If it is NULL, it has been cleaned out by GC.
  39 // This is the vm version of jweak but has different GC lifetimes and policies,
  40 // depending on the type.
  41 
  42 enum WeakHandleType { vm_class_loader_data, vm_string_table_data, vm_resolved_method_table_data, vm_nmethod_keepalive_data };
  43 
  44 template <WeakHandleType T>
  45 class WeakHandle {
  46  public:
  47  private:
  48   oop* _obj;
  49 
  50   WeakHandle(oop* w) : _obj(w) {}
  51   static OopStorage* get_storage();
  52  public:
  53   WeakHandle() : _obj(NULL) {} // needed for init
  54 
  55   static WeakHandle create(Handle obj);
  56   static WeakHandle from_raw(oop* raw);
  57   inline oop resolve() const;
  58   inline oop peek() const;
  59   void release() const;
  60   bool is_null() const { return _obj == NULL; }
  61 
  62   void replace(oop with_obj);
  63   oop* raw() { return _obj; }
  64 
  65   void print() const;
  66   void print_on(outputStream* st) const;
  67 };
  68 
  69 #endif // SHARE_OOPS_WEAKHANDLE_HPP
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