src/hotspot/share/gc/shared/classUnloadingContext.hpp

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#ifndef SHARE_GC_SHARED_CLASSUNLOADINGCONTEXT_HPP
#define SHARE_GC_SHARED_CLASSUNLOADINGCONTEXT_HPP

#include "memory/allocation.hpp"
#include "utilities/growableArray.hpp"

class ClassLoaderData;
class Klass;
class nmethod;

class ClassUnloadingContext : public CHeapObj<mtGC> {
  static ClassUnloadingContext* _context;

  ClassLoaderData* volatile _cld_head;

  const uint _num_nmethod_unlink_workers;

  using NMethodSet = GrowableArrayCHeap<nmethod*, mtGC>;
  NMethodSet** _unlinked_nmethods;

  bool _unregister_nmethods_during_purge;
  bool _lock_nmethod_free_separately;

public:
  static ClassUnloadingContext* context() { assert(_context != nullptr, "context not set"); return _context; }

  // Num_nmethod_unlink_workers configures the maximum numbers of threads unlinking
  //     nmethods.
  // unregister_nmethods_during_purge determines whether unloaded nmethods should
  //     be unregistered from the garbage collector during purge. If not, ,the caller
  //     is responsible to do that later.
  // lock_nmethod_free_separately determines whether freeing the nmethods takes
  //     the CodeCache_lock during the whole operation (=false) or per nmethod
  //     free operation (=true).
  ClassUnloadingContext(uint num_nmethod_unlink_workers,
                        bool unregister_nmethods_during_purge,
                        bool lock_nmethod_free_separately);
  ~ClassUnloadingContext();

  bool has_unloaded_classes() const;

  void register_unloading_class_loader_data(ClassLoaderData* cld);
  void purge_class_loader_data();

  void classes_unloading_do(void f(Klass* const));

  // Register unloading nmethods, potentially in parallel.
  void register_unlinked_nmethod(nmethod* nm);
  void purge_nmethods();
  void free_nmethods();

  void purge_and_free_nmethods() {
    purge_nmethods();
    free_nmethods();
  }
};

#endif // SHARE_GC_SHARED_CLASSUNLOADINGCONTEXT_HPP