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

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#ifndef SHARE_GC_SHARED_WEAKPROCESSOR_HPP
#define SHARE_GC_SHARED_WEAKPROCESSOR_HPP

#include "gc/shared/oopStorageParState.hpp"
#include "gc/shared/oopStorageSetParState.hpp"
#include "gc/shared/workerThread.hpp"
#include "memory/allStatic.hpp"

class WeakProcessorTimes;
class WorkerThreads;

// Helper class to aid in root scanning and cleaning of weak oops in the VM.
//
// New containers of weak oops added to this class will automatically
// be cleaned by all GCs, including the young generation GCs.
class WeakProcessor : AllStatic {
public:
  // Visit all oop*s and apply the keep_alive closure if the referenced
  // object is considered alive by the is_alive closure, otherwise do some
  // container specific cleanup of element holding the oop.
  static void weak_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive);

  // Visit all oop*s and apply the given closure.
  static void oops_do(OopClosure* closure);

  // Parallel version.  Uses ergo_workers() to determine the number of
  // threads to use, limited by the total workers and phase_times'
  // max_threads.
  // IsAlive must be derived from BoolObjectClosure.
  // KeepAlive must be derived from OopClosure.
  template<typename IsAlive, typename KeepAlive>
  static void weak_oops_do(WorkerThreads* workers,
                           IsAlive* is_alive,
                           KeepAlive* keep_alive,
                           WeakProcessorTimes* times);

  // Convenience parallel version.  Uses ergo_workers() to determine the
  // number of threads to use, limited by the total workers.  Implicitly
  // logs phase times.
  // IsAlive must be derived from BoolObjectClosure.
  // KeepAlive must be derived from OopClosure.
  template<typename IsAlive, typename KeepAlive>
  static void weak_oops_do(WorkerThreads* workers,
                           IsAlive* is_alive,
                           KeepAlive* keep_alive,
                           uint indent_log);

  // Uses the total number of weak references and ReferencesPerThread to
  // determine the number of threads to use, limited by max_workers.
  static uint ergo_workers(uint max_workers);

  class Task;

private:
  template<typename IsAlive, typename KeepAlive>
  class CountingClosure;

  class WeakOopsDoTask;
};

class WeakProcessor::Task {
  typedef OopStorage::ParState<false, false> StorageState;

  WeakProcessorTimes* _times;
  uint _nworkers;
  OopStorageSetWeakParState<false, false> _storage_states;

  void initialize();

public:
  Task(uint nworkers);          // No time tracking.
  Task(WeakProcessorTimes* times, uint nworkers);

  template<typename IsAlive, typename KeepAlive>
  void work(uint worker_id, IsAlive* is_alive, KeepAlive* keep_alive);

  void report_num_dead();
};

#endif // SHARE_GC_SHARED_WEAKPROCESSOR_HPP