sweeper.hpp

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/* Copyright 1994-1996 LongView Technologies L.L.C. $Revision: 1.9 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
All rights reserved.

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// This is where the dirty work takes places.

// A Sweeper is an incremental cleaner for
//   Decaying invocation counters and cleanup inline caches in methodOops (MethodSweeper).

class Sweeper : public CHeapObj {
 // Static part
 private:
  static Sweeper* _head;
  static Sweeper* head()        { return _head; }
  static int sweep_seconds;
  static bool _is_running;
  static methodOop _active_method;
  static nmethod*  _active_nmethod;
 public:
  static bool register_active_frame(frame fr);
  static void clear_active_frame();

  static void print_all();
  static void step_all();
  static void add(Sweeper* sweeper);

  static methodOop active_method()  { return _active_method;  }
  static nmethod*  active_nmethod() { return _active_nmethod; }

  // Tells is the sweeper is running
  static bool is_running() { return _is_running; }
 protected:
  Sweeper*  _next;
  Sweeper*  next() const      { return _next; }
  int       _sweep_start;     // time of last activation
  bool      _is_active;       // are we waiting to do something?
  
  bool is_active() const      { return _is_active; }
  void set_active(bool value) { _is_active = value; }

  virtual void  step();
  virtual void  activate();
  virtual void  deactivate();
  virtual int   interval() const = 0;
  virtual char* name()     const = 0;
 public:
  Sweeper();
  virtual void task() = 0;
  void print() const;
};

// Sweeps through the heap for cleaning blockOops  
class HeapSweeper : public Sweeper {
 private:
  OldWaterMark mark;
 private:
  void  task();
  void  activate();
  int   interval() const { return HeapSweeperInterval; }
  char* name()     const { return "HeapSweeper"; }
};

class CodeSweeper : public Sweeper {
 protected:
  int CodeSweeperInterval;    // time interval (sec) between starting zone sweep; computed from half-life time
  double decayFactor;         // decay factor for invocation counts
  int oldHalfLifeTime;        // old half-life time (to dectect changes in half-life setting)
  int fractionPerTask;        // a task invocation does (1 / fractionPerTask) of the entire work

  void  updateInterval();      // check for change in half-life setting
 public:
  CodeSweeper() { oldHalfLifeTime = -1; CodeSweeperInterval = 1; decayFactor = 1; }
  int   interval() const;
};

// Sweeps through the methods and decay counters and cleanup inline caches.
// Traverses all methodOops by traversing the system dictionary.
class MethodSweeper : public CodeSweeper {
 private:
  int index; // next index in systemDictionary to process
 private:
  methodOop excluded_method()                { return Universe::sweeper_method();    }
  void set_excluded_method(methodOop method) { Universe::set_sweeper_method(method); }

  void  task();
  void  method_task(methodOop method);
  int   method_dict_task(objArrayOop methods);
  int   klass_task(klassOop klass);
  void  activate();
  char* name()     const { return "MethodSweeper"; }
  friend class Recompilation;
};

extern MethodSweeper* methodSweeper;      // single instance 

class ZoneSweeper : public CodeSweeper {
 private:
  nmethod* _excluded_nmethod; 
  nmethod* next;
 private:
  nmethod* excluded_nmethod() { return _excluded_nmethod; }
  void set_excluded_nmethod(nmethod* nm) { _excluded_nmethod = nm; }

  void  nmethod_task(nmethod* nm);
  void  task();
  void  activate();
  char* name()     const { return "ZoneSweeper"; }
};

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