/*

 * Copyright (c) 2018, 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_GC_SHARED_OOPSTORAGE_INLINE_HPP

#define SHARE_GC_SHARED_OOPSTORAGE_INLINE_HPP

#include "gc/shared/oopStorage.hpp"

#include "metaprogramming/conditional.hpp"

#include "metaprogramming/isConst.hpp"

#include "oops/oop.hpp"

#include "runtime/safepoint.hpp"

#include "utilities/align.hpp"

#include "utilities/count_trailing_zeros.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

// Array of all active blocks.  Refcounted for lock-free reclaim of

// old array when a new array is allocated for expansion.

class OopStorage::ActiveArray {

  friend class OopStorage::TestAccess;

  size_t _size;

  volatile size_t _block_count;

  mutable volatile int _refcount;

  // Block* _blocks[1];            // Pseudo flexible array member.

  ActiveArray(size_t size);

  ~ActiveArray();

  // Noncopyable

  ActiveArray(const ActiveArray&);

  ActiveArray& operator=(const ActiveArray&);

  static size_t blocks_offset();

  Block* const* base_ptr() const;

  Block* const* block_ptr(size_t index) const;

  Block** block_ptr(size_t index);

public:

  static ActiveArray* create(size_t size, AllocFailType alloc_fail = AllocFailStrategy::EXIT_OOM);

  static void destroy(ActiveArray* ba);

  inline Block* at(size_t i) const;

  size_t size() const;

  size_t block_count() const;

  size_t block_count_acquire() const;

  void increment_refcount() const;

  bool decrement_refcount() const; // Return true if zero, otherwise false

  // Support for OopStorage::allocate.

  // Add block to the end of the array.  Updates block count at the

  // end of the operation, with a release_store. Returns true if the

  // block was added, false if there was no room available.

  // precondition: owner's _allocation_mutex is locked, or at safepoint.

  bool push(Block* block);

  // Support OopStorage::delete_empty_blocks_xxx operations.

  // Remove block from the array.

  // precondition: block must be present at its active_index element.

  void remove(Block* block);

  void copy_from(const ActiveArray* from);

};

inline size_t OopStorage::ActiveArray::blocks_offset() {

  return align_up(sizeof(ActiveArray), sizeof(Block*));

}

inline OopStorage::Block* const* OopStorage::ActiveArray::base_ptr() const {

  const void* ptr = reinterpret_cast<const char*>(this) + blocks_offset();

  return reinterpret_cast<Block* const*>(ptr);

}

inline OopStorage::Block* const* OopStorage::ActiveArray::block_ptr(size_t index) const {

  return base_ptr() + index;

}

inline OopStorage::Block** OopStorage::ActiveArray::block_ptr(size_t index) {

  return const_cast<Block**>(base_ptr() + index);

}

inline OopStorage::Block* OopStorage::ActiveArray::at(size_t index) const {

  assert(index < _block_count, "precondition");

  return *block_ptr(index);

}

// A Block has an embedded AllocationListEntry to provide the links between

// Blocks in an AllocationList.

class OopStorage::AllocationListEntry {

  friend class OopStorage::AllocationList;

  // Members are mutable, and we deal exclusively with pointers to

  // const, to make const blocks easier to use; a block being const

  // doesn't prevent modifying its list state.

  mutable const Block* _prev;

  mutable const Block* _next;

  // Noncopyable.

  AllocationListEntry(const AllocationListEntry&);

  AllocationListEntry& operator=(const AllocationListEntry&);

public:

  AllocationListEntry();

  ~AllocationListEntry();

};

// Fixed-sized array of oops, plus bookkeeping data.

// All blocks are in the storage's _active_array, at the block's _active_index.

// Non-full blocks are in the storage's _allocation_list, linked through the

// block's _allocation_list_entry.  Empty blocks are at the end of that list.

class OopStorage::Block /* No base class, to avoid messing up alignment. */ {

  // _data must be the first non-static data member, for alignment.

  oop _data[BitsPerWord];

  static const unsigned _data_pos = 0; // Position of _data.

  volatile uintx _allocated_bitmask; // One bit per _data element.

  const OopStorage* _owner;

  void* _memory;              // Unaligned storage containing block.

  size_t _active_index;

  AllocationListEntry _allocation_list_entry;

  Block* volatile _deferred_updates_next;

  volatile uintx _release_refcount;

  Block(const OopStorage* owner, void* memory);

  ~Block();

  void check_index(unsigned index) const;

  unsigned get_index(const oop* ptr) const;

  template<typename F, typename BlockPtr>

  static bool iterate_impl(F f, BlockPtr b);

  // Noncopyable.

  Block(const Block&);

  Block& operator=(const Block&);

public:

  const AllocationListEntry& allocation_list_entry() const;

  static size_t allocation_size();

  static size_t allocation_alignment_shift();

  oop* get_pointer(unsigned index);

  const oop* get_pointer(unsigned index) const;

  uintx bitmask_for_index(unsigned index) const;

  uintx bitmask_for_entry(const oop* ptr) const;

  // Allocation bitmask accessors are racy.

  bool is_full() const;

  bool is_empty() const;

  uintx allocated_bitmask() const;

  bool is_deletable() const;

  Block* deferred_updates_next() const;

  void set_deferred_updates_next(Block* new_next);

  bool contains(const oop* ptr) const;

  size_t active_index() const;

  void set_active_index(size_t index);

  static size_t active_index_safe(const Block* block); // Returns 0 if access fails.

  // Returns NULL if ptr is not in a block or not allocated in that block.

  static Block* block_for_ptr(const OopStorage* owner, const oop* ptr);

  oop* allocate();

  static Block* new_block(const OopStorage* owner);

  static void delete_block(const Block& block);

  void release_entries(uintx releasing, Block* volatile* deferred_list);

  template<typename F> bool iterate(F f);

  template<typename F> bool iterate(F f) const;

}; // class Block

inline OopStorage::Block* OopStorage::AllocationList::head() {

  return const_cast<Block*>(_head);

}

inline OopStorage::Block* OopStorage::AllocationList::tail() {

  return const_cast<Block*>(_tail);

}

inline const OopStorage::Block* OopStorage::AllocationList::chead() const {

  return _head;

}

inline const OopStorage::Block* OopStorage::AllocationList::ctail() const {

  return _tail;

}

inline OopStorage::Block* OopStorage::AllocationList::prev(Block& block) {

  return const_cast<Block*>(block.allocation_list_entry()._prev);

}

inline OopStorage::Block* OopStorage::AllocationList::next(Block& block) {

  return const_cast<Block*>(block.allocation_list_entry()._next);

}

inline const OopStorage::Block* OopStorage::AllocationList::prev(const Block& block) const {

  return block.allocation_list_entry()._prev;

}

inline const OopStorage::Block* OopStorage::AllocationList::next(const Block& block) const {

  return block.allocation_list_entry()._next;

}

template<typename Closure>

class OopStorage::OopFn {

public:

  explicit OopFn(Closure* cl) : _cl(cl) {}

  template<typename OopPtr>     // [const] oop*

  bool operator()(OopPtr ptr) const {

    _cl->do_oop(ptr);

    return true;

  }

private:

  Closure* _cl;

};

template<typename Closure>

inline OopStorage::OopFn<Closure> OopStorage::oop_fn(Closure* cl) {

  return OopFn<Closure>(cl);

}

template<typename IsAlive, typename F>

class OopStorage::IfAliveFn {

public:

  IfAliveFn(IsAlive* is_alive, F f) : _is_alive(is_alive), _f(f) {}

  bool operator()(oop* ptr) const {

    bool result = true;

    oop v = *ptr;

    if (v != NULL) {

      if (_is_alive->do_object_b(v)) {

        result = _f(ptr);

      } else {

        *ptr = NULL;            // Clear dead value.

      }

    }

    return result;

  }

private:

  IsAlive* _is_alive;

  F _f;

};

template<typename IsAlive, typename F>

inline OopStorage::IfAliveFn<IsAlive, F> OopStorage::if_alive_fn(IsAlive* is_alive, F f) {

  return IfAliveFn<IsAlive, F>(is_alive, f);

}

template<typename F>

class OopStorage::SkipNullFn {

public:

  SkipNullFn(F f) : _f(f) {}

  template<typename OopPtr>     // [const] oop*

  bool operator()(OopPtr ptr) const {

    return (*ptr != NULL) ? _f(ptr) : true;

  }

private:

  F _f;

};

template<typename F>

inline OopStorage::SkipNullFn<F> OopStorage::skip_null_fn(F f) {

  return SkipNullFn<F>(f);

}

// Inline Block accesses for use in iteration loops.

inline const OopStorage::AllocationListEntry& OopStorage::Block::allocation_list_entry() const {

  return _allocation_list_entry;

}

inline void OopStorage::Block::check_index(unsigned index) const {

  assert(index < ARRAY_SIZE(_data), "Index out of bounds: %u", index);

}

inline oop* OopStorage::Block::get_pointer(unsigned index) {

  check_index(index);

  return &_data[index];

}

inline const oop* OopStorage::Block::get_pointer(unsigned index) const {

  check_index(index);

  return &_data[index];

}

inline uintx OopStorage::Block::allocated_bitmask() const {

  return _allocated_bitmask;

}

inline uintx OopStorage::Block::bitmask_for_index(unsigned index) const {

  check_index(index);

  return uintx(1) << index;

}

// Provide const or non-const iteration, depending on whether BlockPtr

// is const Block* or Block*, respectively.

template<typename F, typename BlockPtr> // BlockPtr := [const] Block*

inline bool OopStorage::Block::iterate_impl(F f, BlockPtr block) {

  uintx bitmask = block->allocated_bitmask();

  while (bitmask != 0) {

    unsigned index = count_trailing_zeros(bitmask);

    bitmask ^= block->bitmask_for_index(index);

    if (!f(block->get_pointer(index))) {

      return false;

    }

  }

  return true;

}

template<typename F>

inline bool OopStorage::Block::iterate(F f) {

  return iterate_impl(f, this);

}

template<typename F>

inline bool OopStorage::Block::iterate(F f) const {

  return iterate_impl(f, this);

}

//////////////////////////////////////////////////////////////////////////////

// Support for serial iteration, always at a safepoint.

// Provide const or non-const iteration, depending on whether Storage is

// const OopStorage* or OopStorage*, respectively.

template<typename F, typename Storage> // Storage := [const] OopStorage

inline bool OopStorage::iterate_impl(F f, Storage* storage) {

  assert_at_safepoint();

  // Propagate const/non-const iteration to the block layer, by using

  // const or non-const blocks as corresponding to Storage.

  typedef typename Conditional<IsConst<Storage>::value, const Block*, Block*>::type BlockPtr;

  ActiveArray* blocks = storage->_active_array;

  size_t limit = blocks->block_count();

  for (size_t i = 0; i < limit; ++i) {

    BlockPtr block = blocks->at(i);

    if (!block->iterate(f)) {

      return false;

    }

  }

  return true;

}

template<typename F>

inline bool OopStorage::iterate_safepoint(F f) {

  return iterate_impl(f, this);

}

template<typename F>

inline bool OopStorage::iterate_safepoint(F f) const {

  return iterate_impl(f, this);

}

template<typename Closure>

inline void OopStorage::oops_do(Closure* cl) {

  iterate_safepoint(oop_fn(cl));

}

template<typename Closure>

inline void OopStorage::oops_do(Closure* cl) const {

  iterate_safepoint(oop_fn(cl));

}

template<typename Closure>

inline void OopStorage::weak_oops_do(Closure* cl) {

  iterate_safepoint(skip_null_fn(oop_fn(cl)));

}

template<typename IsAliveClosure, typename Closure>

inline void OopStorage::weak_oops_do(IsAliveClosure* is_alive, Closure* cl) {

  iterate_safepoint(if_alive_fn(is_alive, oop_fn(cl)));

}

#endif // include guard