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Java example source code file (genOopClosures.hpp)

This example Java source code file (genOopClosures.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

cardtablers, defnewgeneration, extendedoopclosure, fastscanclosure, generation, generictaskqueue, heapword, klassremset, null, oopsingenclosure, oopsinklassorgenclosure, share_vm_memory_genoopclosures_hpp, verifyoopclosure

The genOopClosures.hpp Java example source code

/*
 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_MEMORY_GENOOPCLOSURES_HPP
#define SHARE_VM_MEMORY_GENOOPCLOSURES_HPP

#include "memory/iterator.hpp"
#include "oops/oop.hpp"

class Generation;
class HeapWord;
class CardTableRS;
class CardTableModRefBS;
class DefNewGeneration;
class KlassRemSet;

template<class E, MEMFLAGS F, unsigned int N> class GenericTaskQueue;
typedef GenericTaskQueue<oop, mtGC, TASKQUEUE_SIZE> OopTaskQueue;
template<class T, MEMFLAGS F> class GenericTaskQueueSet;
typedef GenericTaskQueueSet<OopTaskQueue, mtGC> OopTaskQueueSet;

// Closure for iterating roots from a particular generation
// Note: all classes deriving from this MUST call this do_barrier
// method at the end of their own do_oop method!
// Note: no do_oop defined, this is an abstract class.

class OopsInGenClosure : public ExtendedOopClosure {
 private:
  Generation*  _orig_gen;     // generation originally set in ctor
  Generation*  _gen;          // generation being scanned

 protected:
  // Some subtypes need access.
  HeapWord*    _gen_boundary; // start of generation
  CardTableRS* _rs;           // remembered set

  // For assertions
  Generation* generation() { return _gen; }
  CardTableRS* rs() { return _rs; }

  // Derived classes that modify oops so that they might be old-to-young
  // pointers must call the method below.
  template <class T> void do_barrier(T* p);

  // Version for use by closures that may be called in parallel code.
  template <class T> void par_do_barrier(T* p);

 public:
  OopsInGenClosure() : ExtendedOopClosure(NULL),
    _orig_gen(NULL), _gen(NULL), _gen_boundary(NULL), _rs(NULL) {};

  OopsInGenClosure(Generation* gen);
  void set_generation(Generation* gen);

  void reset_generation() { _gen = _orig_gen; }

  // Problem with static closures: must have _gen_boundary set at some point,
  // but cannot do this until after the heap is initialized.
  void set_orig_generation(Generation* gen) {
    _orig_gen = gen;
    set_generation(gen);
  }

  HeapWord* gen_boundary() { return _gen_boundary; }

};

// Super class for scan closures. It contains code to dirty scanned Klasses.
class OopsInKlassOrGenClosure: public OopsInGenClosure {
  Klass* _scanned_klass;
 public:
  OopsInKlassOrGenClosure(Generation* g) : OopsInGenClosure(g), _scanned_klass(NULL) {}
  void set_scanned_klass(Klass* k) {
    assert(k == NULL || _scanned_klass == NULL, "Must be");
    _scanned_klass = k;
  }
  bool is_scanning_a_klass() { return _scanned_klass != NULL; }
  void do_klass_barrier();
};

// Closure for scanning DefNewGeneration.
//
// This closure will perform barrier store calls for ALL
// pointers in scanned oops.
class ScanClosure: public OopsInKlassOrGenClosure {
 protected:
  DefNewGeneration* _g;
  HeapWord*         _boundary;
  bool              _gc_barrier;
  template <class T> inline void do_oop_work(T* p);
 public:
  ScanClosure(DefNewGeneration* g, bool gc_barrier);
  virtual void do_oop(oop* p);
  virtual void do_oop(narrowOop* p);
  inline void do_oop_nv(oop* p);
  inline void do_oop_nv(narrowOop* p);
  Prefetch::style prefetch_style() {
    return Prefetch::do_write;
  }
};

// Closure for scanning DefNewGeneration.
//
// This closure only performs barrier store calls on
// pointers into the DefNewGeneration. This is less
// precise, but faster, than a ScanClosure
class FastScanClosure: public OopsInKlassOrGenClosure {
 protected:
  DefNewGeneration* _g;
  HeapWord*         _boundary;
  bool              _gc_barrier;
  template <class T> inline void do_oop_work(T* p);
 public:
  FastScanClosure(DefNewGeneration* g, bool gc_barrier);
  virtual void do_oop(oop* p);
  virtual void do_oop(narrowOop* p);
  inline void do_oop_nv(oop* p);
  inline void do_oop_nv(narrowOop* p);
  Prefetch::style prefetch_style() {
    return Prefetch::do_write;
  }
};

class KlassScanClosure: public KlassClosure {
  OopsInKlassOrGenClosure* _scavenge_closure;
  // true if the the modified oops state should be saved.
  bool                     _accumulate_modified_oops;
 public:
  KlassScanClosure(OopsInKlassOrGenClosure* scavenge_closure,
                   KlassRemSet* klass_rem_set_policy);
  void do_klass(Klass* k);
};

class FilteringClosure: public ExtendedOopClosure {
 private:
  HeapWord*   _boundary;
  ExtendedOopClosure* _cl;
 protected:
  template <class T> inline void do_oop_work(T* p) {
    T heap_oop = oopDesc::load_heap_oop(p);
    if (!oopDesc::is_null(heap_oop)) {
      oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
      if ((HeapWord*)obj < _boundary) {
        _cl->do_oop(p);
      }
    }
  }
 public:
  FilteringClosure(HeapWord* boundary, ExtendedOopClosure* cl) :
    ExtendedOopClosure(cl->_ref_processor), _boundary(boundary),
    _cl(cl) {}
  virtual void do_oop(oop* p);
  virtual void do_oop(narrowOop* p);
  inline void do_oop_nv(oop* p)       { FilteringClosure::do_oop_work(p); }
  inline void do_oop_nv(narrowOop* p) { FilteringClosure::do_oop_work(p); }
  virtual bool do_metadata()          { return do_metadata_nv(); }
  inline bool do_metadata_nv()        { assert(!_cl->do_metadata(), "assumption broken, must change to 'return _cl->do_metadata()'"); return false; }
};

// Closure for scanning DefNewGeneration's weak references.
// NOTE: very much like ScanClosure but not derived from
//  OopsInGenClosure -- weak references are processed all
//  at once, with no notion of which generation they were in.
class ScanWeakRefClosure: public OopClosure {
 protected:
  DefNewGeneration* _g;
  HeapWord*         _boundary;
  template <class T> inline void do_oop_work(T* p);
 public:
  ScanWeakRefClosure(DefNewGeneration* g);
  virtual void do_oop(oop* p);
  virtual void do_oop(narrowOop* p);
  inline void do_oop_nv(oop* p);
  inline void do_oop_nv(narrowOop* p);
};

class VerifyOopClosure: public OopClosure {
 protected:
  template <class T> inline void do_oop_work(T* p) {
    oop obj = oopDesc::load_decode_heap_oop(p);
    guarantee(obj->is_oop_or_null(), err_msg("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj));
  }
 public:
  virtual void do_oop(oop* p);
  virtual void do_oop(narrowOop* p);
  static VerifyOopClosure verify_oop;
};

#endif // SHARE_VM_MEMORY_GENOOPCLOSURES_HPP

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