/*

 * Copyright (c) 2019, SAP SE. All rights reserved.

 * Copyright (c) 2019, 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

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 */

#ifndef SHARE_MEMORY_METASPACE_LEFTOVERBINS_HPP

#define SHARE_MEMORY_METASPACE_LEFTOVERBINS_HPP

#include "memory/allocation.hpp"

#include "memory/metaspace/blockListArray.hpp"

#include "memory/metaspace/counter.hpp"

#include "utilities/bitMap.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

class outputStream;

namespace metaspace {

// The LeftOverManager is responsible for managing small leftover-

// and deallocated blocks.

// They come from two sources:

// a) the leftover space left in a chunk when a chunk gets retired

//    because it cannot serve a requested allocation. These blocks

//    can be largeish (100s - 1000s of words).

// b) when a metaspace allocation is deallocated prematurely - e.g.

//    due to interrupted class loading. These blocks are small or

//    very small.

class LeftOverManager : public CHeapObj<mtInternal> {

  typedef BlockListArray<2, 2, 16> VerySmallBinsType;

  VerySmallBinsType _very_small_bins;

  block_t* _large_block_reserve;

  // The current large block we gnaw on

  MetaWord* _current;

  size_t _current_size;

  SizeCounter _total_word_size;

  // Take the topmost block from the large block reserve list

  // and make it current.

  inline void prime_current();

  // Allocate from current block. Returns NULL if current block

  // is too small.

  inline MetaWord* alloc_from_current(size_t word_size);

  void large_block_statistics(block_stats_t* stats) const;

public:

  static size_t minimal_word_size() {

    return VerySmallBinsType::minimal_word_size();

  }

  LeftOverManager() :

    _very_small_bins(),

    _large_block_reserve(NULL),

    _current(NULL),

    _current_size(0)

  {}

  inline void add_block(MetaWord* p, size_t word_size);

  inline MetaWord* get_block(size_t requested_word_size);

#ifdef ASSERT

  void verify() const;

#endif

  void statistics(block_stats_t* stats) const;

  void print(outputStream* st, bool detailed = false) const;

  size_t total_word_size() const { return _total_word_size.get(); }

};

} // namespace metaspace

#endif // SHARE_MEMORY_METASPACE_CHUNKMANAGER_HPP