/*

 * Copyright (c) 2003, 2008, 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.

 *

 */

// All heaps contains a "permanent generation," containing permanent

// (reflective) objects.  This is like a regular generation in some ways,

// but unlike one in others, and so is split apart.

class PermanentGenerationSpec;

// This is the "generation" view of a CompactingPermGen.

// NOTE: the shared spaces used for CDS are here handled in

// a somewhat awkward and potentially buggy fashion, see CR 6801625.

// This infelicity should be fixed, see CR 6897789.

class CompactingPermGenGen: public OneContigSpaceCardGeneration {

  friend class VMStructs;

  // Abstractly, this is a subtype that gets access to protected fields.

  friend class CompactingPermGen;

private:

  // Shared spaces

  PermanentGenerationSpec* _spec;

  size_t _shared_space_size;

  VirtualSpace _ro_vs;

  VirtualSpace _rw_vs;

  VirtualSpace _md_vs;

  VirtualSpace _mc_vs;

  BlockOffsetSharedArray* _ro_bts;

  BlockOffsetSharedArray* _rw_bts;

  OffsetTableContigSpace* _ro_space;

  OffsetTableContigSpace* _rw_space;

  // With shared spaces there is a dichotomy in the use of the

  // _virtual_space of the generation.  There is a portion of the

  // _virtual_space that is used for the unshared part of the

  // permanent generation and a portion that is reserved for the shared part.

  // The _reserved field in the generation represents both the

  // unshared and shared parts of the generation.  The _reserved

  // variable is initialized for only the unshared part but is

  // later extended to include the shared part during initialization

  // if shared spaces are being used.

  // The reserved size for the _virtual_space for CompactingPermGenGen

  // is the size of the space for the permanent generation including the

  // the shared spaces.  This can be seen by the use of MaxPermSize

  // in the allocation of PermanentGenerationSpec.  The space for the

  // shared spaces is committed separately (???).

  // In general at initialization only a part of the

  // space for the unshared part of the permanent generation is

  // committed and more is committed as the permanent generation is

  // grown.  In growing the permanent generation the capacity() and

  // max_capacity() of the generation are used.  For the permanent

  // generation (implemented with a CompactingPermGenGen) the capacity()

  // is taken from the capacity of the space (_the_space variable used for the

  // unshared part of the generation) and the max_capacity() is based

  // on the size of the _reserved variable (which includes the size of the

  // shared spaces) minus the size of the shared spaces.

  // These values are redundant, but are called out separately to avoid

  // going through heap/space/gen pointers for performance.

  static HeapWord* unshared_bottom;

  static HeapWord* unshared_end;

  static HeapWord* shared_bottom;

  static HeapWord* readonly_bottom;

  static HeapWord* readonly_end;

  static HeapWord* readwrite_bottom;

  static HeapWord* readwrite_end;

  static HeapWord* miscdata_bottom;

  static HeapWord* miscdata_end;

  static HeapWord* misccode_bottom;

  static HeapWord* misccode_end;

  static HeapWord* shared_end;

  // List of klassOops whose vtbl entries are used to patch others.

  static void**        _vtbl_list;

  // Performance Counters

  GenerationCounters*  _gen_counters;

  CSpaceCounters*      _space_counters;

  void initialize_performance_counters();

public:

  enum {

    vtbl_list_size = 16, // number of entries in the shared space vtable list.

    num_virtuals = 200   // number of virtual methods in Klass (or

                         // subclass) objects, or greater.

  };

  enum {

    ro = 0,  // read-only shared space in the heap

    rw = 1,  // read-write shared space in the heap

    md = 2,  // miscellaneous data for initializing tables, etc.

    mc = 3,  // miscellaneous code - vtable replacement.

    n_regions = 4

  };

  CompactingPermGenGen(ReservedSpace rs, ReservedSpace shared_rs,

                       size_t initial_byte_size, int level, GenRemSet* remset,

                       ContiguousSpace* space,

                       PermanentGenerationSpec* perm_spec);

  const char* name() const {

    return "compacting perm gen";

  }

  const char* short_name() const {

    return "Perm";

  }

  // Return the maximum capacity for the object space.  This

  // explicitly does not include the shared spaces.

  size_t max_capacity() const;

  void update_counters();

  void compute_new_size() {

    assert(false, "Should not call this -- handled at PermGen level.");

  }

  bool must_be_youngest() const { return false; }

  bool must_be_oldest() const { return false; }

  OffsetTableContigSpace* ro_space() const { return _ro_space; }

  OffsetTableContigSpace* rw_space() const { return _rw_space; }

  VirtualSpace*           md_space()       { return &_md_vs; }

  VirtualSpace*           mc_space()       { return &_mc_vs; }

  ContiguousSpace* unshared_space() const { return _the_space; }

  static bool inline is_shared(const oopDesc* p) {

    return (HeapWord*)p >= shared_bottom && (HeapWord*)p < shared_end;

  }

  // RedefineClasses note: this tester is used to check residence of

  // the specified oop in the shared readonly space and not whether

  // the oop is readonly.

  static bool inline is_shared_readonly(const oopDesc* p) {

    return (HeapWord*)p >= readonly_bottom && (HeapWord*)p < readonly_end;

  }

  // RedefineClasses note: this tester is used to check residence of

  // the specified oop in the shared readwrite space and not whether

  // the oop is readwrite.

  static bool inline is_shared_readwrite(const oopDesc* p) {

    return (HeapWord*)p >= readwrite_bottom && (HeapWord*)p < readwrite_end;

  }

  bool is_in_unshared(const void* p) const {

    return OneContigSpaceCardGeneration::is_in(p);

  }

  bool is_in_shared(const void* p) const {

   return p >= shared_bottom && p < shared_end;

   }

  inline bool is_in(const void* p) const {

    return is_in_unshared(p) || is_in_shared(p);

  }

  inline PermanentGenerationSpec* spec() const { return _spec; }

  inline void set_spec(PermanentGenerationSpec* spec) { _spec = spec; }

  void pre_adjust_pointers();

  void adjust_pointers();

  void space_iterate(SpaceClosure* blk, bool usedOnly = false);

  void print_on(outputStream* st) const;

  void younger_refs_iterate(OopsInGenClosure* blk);

  void compact();

  void post_compact();

  size_t contiguous_available() const;

  void clear_remembered_set();

  void invalidate_remembered_set();

  inline bool block_is_obj(const HeapWord* addr) const {

    if      (addr < the_space()->top()) return true;

    else if (addr < the_space()->end()) return false;

    else if (addr < ro_space()->top())  return true;

    else if (addr < ro_space()->end())  return false;

    else if (addr < rw_space()->top())  return true;

    else                                return false;

  }

  inline size_t block_size(const HeapWord* addr) const {

    if (addr < the_space()->top()) {

      return oop(addr)->size();

    }

    else if (addr < the_space()->end()) {

      assert(addr == the_space()->top(), "non-block head arg to block_size");

      return the_space()->end() - the_space()->top();

    }

    else if (addr < ro_space()->top()) {

      return oop(addr)->size();

    }

    else if (addr < ro_space()->end()) {

      assert(addr == ro_space()->top(), "non-block head arg to block_size");

      return ro_space()->end() - ro_space()->top();

    }

    else if (addr < rw_space()->top()) {

      return oop(addr)->size();

    }

    else {

      assert(addr == rw_space()->top(), "non-block head arg to block_size");

      return rw_space()->end() - rw_space()->top();

    }

  }

  static void generate_vtable_methods(void** vtbl_list,

                                      void** vtable,

                                      char** md_top, char* md_end,

                                      char** mc_top, char* mc_end);

  void verify(bool allow_dirty);

  // Serialization

  static void initialize_oops() KERNEL_RETURN;

  static void serialize_oops(SerializeOopClosure* soc);

  void serialize_bts(SerializeOopClosure* soc);

  // Initiate dumping of shared file.

  static jint dump_shared(GrowableArray<oop>* class_promote_order, TRAPS);

  // JVM/TI RedefineClasses() support:

  // Remap the shared readonly space to shared readwrite, private if

  // sharing is enabled. Simply returns true if sharing is not enabled

  // or if the remapping has already been done by a prior call.

  static bool remap_shared_readonly_as_readwrite();

};