MemoryPool.hpp

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/** A very simple memory pool to minimize allocation time in memory-limited
 * Xeon Phi cards.
 * Basically, it's a circular buffer.
 * Allocation is simply done by returning the current offset and then shifting
 * the offset (and wrapping around it when necessary).
 *
 * Example:
 *
 * foo(); // internally uses pool->Allocate(), which will shift the offset
 * size_t fooEnd = pool->getTail();
 * ...
 * boo(); // internally uses pool->Allocate()
 * ...
 * size_t barBegin = pool->getTail();
 * bar();
 * ...
 * pool->setHeadOffset(fooEnd); // free those allocated before foo
 * ...
 * pool->setTailOffset(barBegin); // free those allocated after boo
 */

#pragma once

#include <cstdlib>

namespace SpMP
{

class MemoryPool
{
public :
  MemoryPool();
  MemoryPool(size_t sz);
  ~MemoryPool();

  void initialize(size_t sz);
  void finalize();

  void setHead(size_t offset);
  void setTail(size_t offset);

  size_t getHead() const;
  size_t getTail() const;

  void *allocate(size_t sz, int align = 64);
  void *allocateFront(size_t sz, int align = 64);
  void deallocateAll();

  template<typename T> T *allocate(size_t cnt) {
    return (T *)allocate(sizeof(T)*cnt);
  }
  template<typename T> T *allocateFront(size_t cnt) {
    return (T *)allocateFront(sizeof(T)*cnt);
  }

  /**
   * @return true if ptr is in this pool
   */
  bool contains(const void *ptr) const;
  
  static MemoryPool *getSingleton();

#ifdef HBW_ALLOC
  static MemoryPool *getMemkindSingleton();
#endif

private :
  size_t size_;
  size_t head_, tail_;
  char *buffer_;
};

} // namespace SpMP