Program Listing for File DynamicPoolList.hpp

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//////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2016-20, Lawrence Livermore National Security, LLC and Umpire
// project contributors. See the COPYRIGHT file for details.
//
// SPDX-License-Identifier: (MIT)
//////////////////////////////////////////////////////////////////////////////
#ifndef UMPIRE_DynamicPoolList_HPP
#define UMPIRE_DynamicPoolList_HPP

#include <functional>
#include <memory>
#include <vector>

#include "umpire/strategy/AllocationStrategy.hpp"
#include "umpire/strategy/DynamicSizePool.hpp"

namespace umpire {

class Allocator;

namespace strategy {

/*!
 * \brief Simple dynamic pool for allocations
 *
 * This AllocationStrategy uses Simpool to provide pooling for allocations of
 * any size. The behavior of the pool can be controlled by two parameters: the
 * initial allocation size, and the minimum allocation size.
 *
 * The initial size controls how large the first piece of memory allocated is,
 * and the minimum size controls the lower bound on all future chunk
 * allocations.
 */
class DynamicPoolList : public AllocationStrategy {
 public:
  using CoalesceHeuristic =
      std::function<bool(const strategy::DynamicPoolList&)>;

  static CoalesceHeuristic percent_releasable(int percentage);

  /*!
   * \brief Construct a new DynamicPoolList.
   *
   * \param name Name of this instance of the DynamicPoolList.
   * \param id Id of this instance of the DynamicPoolList.
   * \param allocator Allocation resource that pool uses
   * \param first_minimum_pool_allocation_size Minimum size the pool initially
   * allocates \param next_minimum_pool_allocation_size The minimum size of all
   * future allocations. \param align_bytes Number of bytes with which to align
   * allocation sizes (power-of-2) \param do_heuristic Heuristic for when to
   * perform coalesce operation
   */
  DynamicPoolList(
      const std::string& name, int id, Allocator allocator,
      const std::size_t first_minimum_pool_allocation_size = (512 * 1024 *
                                                              1024),
      const std::size_t next_minimum_pool_allocation_size = (1 * 1024 * 1024),
      const std::size_t alignment = 16,
      CoalesceHeuristic should_coalesce = percent_releasable(100)) noexcept;

  DynamicPoolList(const DynamicPoolList&) = delete;

  void* allocate(size_t bytes) override;
  void deallocate(void* ptr) override;
  void release() override;

  std::size_t getActualSize() const noexcept override;
  std::size_t getCurrentSize() const noexcept override;

  Platform getPlatform() noexcept override;

  MemoryResourceTraits getTraits() const noexcept final override;

  /*!
   * \brief Get the number of bytes that may be released back to resource
   *
   * A memory pool has a set of blocks that have no allocations
   * against them.  If the size of the set is greater than one, then
   * the pool will have a number of bytes that may be released back to
   * the resource or coalesced into a larger block.
   *
   * \return The total number of bytes that are releasable
   */
  std::size_t getReleasableSize() const noexcept;

  /*!
   * \brief Get the number of memory blocks that the pool has
   *
   * \return The total number of blocks that are allocated by the pool
   */
  std::size_t getBlocksInPool() const noexcept;

  /*!
   * \brief Get the largest allocatable number of bytes from pool before
   * the pool will grow.
   *
   * return The largest number of bytes that may be allocated without
   * causing pool growth
   */
  std::size_t getLargestAvailableBlock() const noexcept;

  void coalesce() noexcept;

 private:
  strategy::AllocationStrategy* m_allocator;
  DynamicSizePool<> dpa;
  CoalesceHeuristic m_should_coalesce;
};

} // end of namespace strategy
} // end namespace umpire

#endif // UMPIRE_DynamicPoolList_HPP