src/hotspot/share/memory/metaspace/metablock.hpp

/*
 * Copyright (c) 2023 Red Hat, Inc. All rights reserved.
 * Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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#ifndef SHARE_MEMORY_METASPACE_METABLOCK_HPP
#define SHARE_MEMORY_METASPACE_METABLOCK_HPP

#include "utilities/globalDefinitions.hpp"

class outputStream;

namespace metaspace {

// Tiny structure to be passed by value
class MetaBlock {

  MetaWord* _base;
  size_t _word_size;

public:

  MetaBlock(MetaWord* p, size_t word_size) :
    _base(word_size == 0 ? nullptr : p), _word_size(word_size) {}
  MetaBlock() : MetaBlock(nullptr, 0) {}

  MetaWord* base() const { return _base; }
  const MetaWord* end() const { return _base + _word_size; }
  size_t word_size() const { return _word_size; }
  bool is_empty() const { return _base == nullptr; }
  bool is_nonempty() const { return _base != nullptr; }
  void reset() { _base = nullptr; _word_size = 0; }

  bool operator==(const MetaBlock& rhs) const {
    return base() == rhs.base() &&
           word_size() == rhs.word_size();
  }

  // Split off tail block.
  inline MetaBlock split_off_tail(size_t tailsize);

  DEBUG_ONLY(inline void verify() const;)

  // Convenience functions
  inline bool is_aligned_base(size_t alignment_words) const;
  inline bool is_aligned_size(size_t alignment_words) const;

  void print_on(outputStream* st) const;
};

#define METABLOCKFORMAT                 "block (@" PTR_FORMAT " word size %zu)"
#define METABLOCKFORMATARGS(__block__)  p2i((__block__).base()), (__block__).word_size()

} // namespace metaspace

#endif // SHARE_MEMORY_METASPACE_METABLOCK_HPP