JLANG::JAllocator Class Reference

Memory management for small objects. More...

#include <JAllocator.hh>

Inheritance diagram for JLANG::JAllocator:

Public Member Functions
	JAllocator (const std::size_t block_size, const JBlock_t number_of_blocks=std::numeric_limits< JBlock_t >::max())
	Constructor. More...
long long int	getTotalRAM ()
	Get total used RAM. More...
long long int	getFreeRAM ()
	Get total free RAM. More...
void *	allocate ()
	Allocate memory. More...
void	free (void *p)
	Deallocate memory. More...

Private Types
typedef JAllocatorBuffer::JBlock_t	JBlock_t

Private Attributes
std::size_t	BLOCK_SIZE
JBlock_t	numberOfBlocks
JAllocatorBuffer *	pAlloc
JAllocatorBuffer *	pDealloc

Detailed Description

Memory management for small objects.

This object allocator consitutes a comprimise between speed and memory overhead.

Source code is taken from reference: A. Alexandrescu, Modern C++ Design, Addison Wesley.

Definition at line 116 of file JAllocator.hh.

Member Typedef Documentation

typedef JAllocatorBuffer::JBlock_t JLANG::JAllocator::JBlock_t

private

Definition at line 121 of file JAllocator.hh.

Constructor & Destructor Documentation

JLANG::JAllocator::JAllocator ( const std::size_t  block_size, const JBlock_t  number_of_blocks = std::numeric_limits<JBlock_t>::max()  )

inline

Constructor.

Parameters

block_size	number of bytes
number_of_blocks	number of blocks

Definition at line 136 of file JAllocator.hh.

                                                                                        :
      std::vector<JAllocatorBuffer>(),
      BLOCK_SIZE    (block_size),
      numberOfBlocks(number_of_blocks),
      pAlloc  (NULL),
      pDealloc(NULL)
    {}

Member Function Documentation

long long int JLANG::JAllocator::getTotalRAM ( )

inline

Get total used RAM.

Returns

number of bytes

Definition at line 151 of file JAllocator.hh.

    {
      return this->size() * BLOCK_SIZE * numberOfBlocks;
    }

long long int JLANG::JAllocator::getFreeRAM ( )

inline

Get total free RAM.

Returns

number of bytes

Definition at line 162 of file JAllocator.hh.

    {
      long long int n = 0;

      for (const_iterator i = this->begin(); i != this->end(); ++i) {
        n += i->numberOfFreeBlocks;
      }

      return n * BLOCK_SIZE;
    }

void* JLANG::JAllocator::allocate ( )

inline

Allocate memory.

Returns

pointer to avaible memory

Definition at line 179 of file JAllocator.hh.

    {
      if (pAlloc == NULL || pAlloc->numberOfFreeBlocks == 0) {

        for (iterator i = this->begin(); ; ++i) {

          if (i == this->end()) {

            this->push_back(JAllocatorBuffer(BLOCK_SIZE, numberOfBlocks));

            pAlloc   = &this->back();
            pDealloc = pAlloc;
            break;
          }

          if (i->numberOfFreeBlocks != 0) {

            pAlloc   = &(*i);
            break;
          }
        }

        if (pAlloc == NULL) {
          THROW(JException, "JAllocator::allocate() no buffer available.");
        }

        if (pAlloc->numberOfFreeBlocks == 0) {
          THROW(JException, "JAllocator::allocate() no buffer available.");
        }
      }

      return pAlloc->allocate(BLOCK_SIZE);
    }

void JLANG::JAllocator::free ( void *  p )

inline

Deallocate memory.

Parameters

p	pointer to memory to be freed

Definition at line 219 of file JAllocator.hh.

    {
      if (this->size() != 1) {

        if (p <  pDealloc->buffer ||
            p >= pDealloc->buffer + numberOfBlocks * BLOCK_SIZE) {
          
          for (std::vector<JAllocatorBuffer>::iterator i = this->begin(); i != this->end(); ++i) {
            
            if (p >= i->buffer && 
                p <  i->buffer + numberOfBlocks * BLOCK_SIZE) {
              pDealloc = &(*i);
              break;
            }
          }
        }
      }


      pDealloc->free(p, BLOCK_SIZE);


      if (this->size() != 1 && pDealloc->numberOfFreeBlocks == numberOfBlocks) {

        std::vector<JAllocatorBuffer>::reverse_iterator i = this->rbegin();

        for ( ; &(*i) != pDealloc && i->numberOfFreeBlocks == numberOfBlocks; ++i) {}

        if (&(*i) != pDealloc) {

          std::swap(*pDealloc, *i);

          if (i != this->rend()) {

            delete [] this->rbegin()->buffer;
            
            this->pop_back();
          }
        }
      }

      pAlloc = pDealloc;
    }

Member Data Documentation

std::size_t JLANG::JAllocator::BLOCK_SIZE

private

Definition at line 123 of file JAllocator.hh.

JBlock_t JLANG::JAllocator::numberOfBlocks

private

Definition at line 124 of file JAllocator.hh.

JAllocatorBuffer* JLANG::JAllocator::pAlloc

private

Definition at line 126 of file JAllocator.hh.

JAllocatorBuffer* JLANG::JAllocator::pDealloc

private

Definition at line 127 of file JAllocator.hh.

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The documentation for this class was generated from the following file:

• JAllocator.hh