/*

 * 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

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#include "memory/metaspace/metabase.hpp"

#include "memory/metaspace/metaspaceCommon.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

class MetachunkTest;

namespace metaspace {

class VirtualSpaceNode;

//  Metachunk - Quantum of allocation from a Virtualspace

//    Metachunks are reused (when freed are put on a global freelist) and

//    have no permanent association to a SpaceManager.

//            +--------------+ <- end    --+       --+

//            |              |             |         |

//            |              |             | free    |

//            |              |             |         |

//            |              |             |         | size | capacity

//            |              |             |         |

//            |              | <- top   -- +         |

//            |              |             |         |

//            |              |             | used    |

//            |              |             |         |

//            |              |             |         |

//            +--------------+ <- bottom --+       --+

enum ChunkOrigin {

  // Chunk normally born (via take_from_committed)

  origin_normal = 1,

  // Chunk was born as padding chunk

  origin_pad = 2,

  // Chunk was born as leftover chunk in VirtualSpaceNode::retire

  origin_leftover = 3,

  // Chunk was born as result of a merge of smaller chunks

  origin_merge = 4,

  // Chunk was born as result of a split of a larger chunk

  origin_split = 5,

  origin_minimum = origin_normal,

  origin_maximum = origin_split,

  origins_count = origin_maximum + 1

};

inline bool is_valid_chunkorigin(ChunkOrigin origin) {

  return origin == origin_normal ||

    origin == origin_pad ||

    origin == origin_leftover ||

    origin == origin_merge ||

    origin == origin_split;

}

class Metachunk : public Metabase<Metachunk> {

  friend class ::MetachunkTest;

  // The VirtualSpaceNode containing this chunk.

  VirtualSpaceNode* const _container;

  // Current allocation top.

  MetaWord* _top;

  // A 32bit sentinel for debugging purposes.

  enum { CHUNK_SENTINEL = 0x4d4554EF,  // "MET"

         CHUNK_SENTINEL_INVALID = 0xFEEEEEEF

  };

  uint32_t _sentinel;

  const ChunkIndex _chunk_type;

  const bool _is_class;

  // Whether the chunk is free (in freelist) or in use by some class loader.

  bool _is_tagged_free;

  ChunkOrigin _origin;

  int _use_count;

  MetaWord* initial_top() const { return (MetaWord*)this + overhead(); }

  MetaWord* top() const         { return _top; }

 public:

  // Metachunks are allocated out of a MetadataVirtualSpace and

  // and use some of its space to describe itself (plus alignment

  // considerations).  Metadata is allocated in the rest of the chunk.

  // This size is the overhead of maintaining the Metachunk within

  // the space.

  // Alignment of each allocation in the chunks.

  static size_t object_alignment();

  // Size of the Metachunk header, in words, including alignment.

  static size_t overhead();

  Metachunk(ChunkIndex chunktype, bool is_class, size_t word_size, VirtualSpaceNode* container);

  MetaWord* allocate(size_t word_size);

  VirtualSpaceNode* container() const { return _container; }

  MetaWord* bottom() const { return (MetaWord*) this; }

  // Reset top to bottom so chunk can be reused.

  void reset_empty() { _top = initial_top(); clear_next(); clear_prev(); }

  bool is_empty() { return _top == initial_top(); }

  // used (has been allocated)

  // free (available for future allocations)

  size_t word_size() const { return size(); }

  size_t used_word_size() const;

  size_t free_word_size() const;

  bool is_tagged_free() { return _is_tagged_free; }

  void set_is_tagged_free(bool v) { _is_tagged_free = v; }

  bool contains(const void* ptr) { return bottom() <= ptr && ptr < _top; }

  void print_on(outputStream* st) const;

  bool is_valid_sentinel() const        { return _sentinel == CHUNK_SENTINEL; }

  void remove_sentinel()                { _sentinel = CHUNK_SENTINEL_INVALID; }

  int get_use_count() const             { return _use_count; }

  void inc_use_count()                  { _use_count ++; }

  ChunkOrigin get_origin() const        { return _origin; }

  void set_origin(ChunkOrigin orig)     { _origin = orig; }

  ChunkIndex get_chunk_type() const     { return _chunk_type; }

  bool is_class() const                 { return _is_class; }

  DEBUG_ONLY(void mangle(juint word_value);)

  DEBUG_ONLY(void verify() const;)

};

// Helper function that does a bunch of checks for a chunk.

DEBUG_ONLY(void do_verify_chunk(Metachunk* chunk);)

// Given a Metachunk, update its in-use information (both in the

// chunk and the occupancy map).

void do_update_in_use_info_for_chunk(Metachunk* chunk, bool inuse);

} // namespace metaspace