~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; version 2 of the License.

   This program 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 for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/**

 * @file

 * @brief Memory root declarations

 */

#pragma once

#include <drizzled/common_fwd.h>

#include <drizzled/definitions.h>

#include <drizzled/util/data_ref.h>

#include <drizzled/visibility.h>

namespace drizzled {

/**

 * @namespace drizzled::memory

 * Memory allocation utils

 *

 * NB: This namespace documentation may not seem very useful, but without a

 * comment on the namespace Doxygen won't extract any documentation for

 * namespace members.

 */

namespace memory {

static const int KEEP_PREALLOC= 1;

/* move used to free list and reuse them */

static const int MARK_BLOCKS_FREE= 2;

namespace internal 

{

  class UsedMemory

  {			   /* struct for once_alloc (block) */

  public:

    UsedMemory *next;	   /* Next block in use */

    size_t left;		   /* memory left in block  */            

    size_t size;		   /* size of block */

  };

}

static const size_t ROOT_MIN_BLOCK_SIZE= (MALLOC_OVERHEAD + sizeof(internal::UsedMemory) + 8);

class DRIZZLED_API Root

{

public:

  Root() :

    free(0),

    used(0),

    pre_alloc(0),

    min_malloc(0),

    block_size(0),

    block_num(0),

    first_block_usage(0)

  { }

  Root(size_t block_size_arg)

  {

    free= used= pre_alloc= 0;

    min_malloc= 32;

    block_size= block_size_arg - memory::ROOT_MIN_BLOCK_SIZE;

    block_num= 4;			/* We shift this with >>2 */

    first_block_usage= 0;

  }

  /**

   * blocks with free memory in it 

   */

  internal::UsedMemory *free;

  /**

   * blocks almost without free memory 

   */

  internal::UsedMemory *used;

  /**

   * preallocated block 

   */

  internal::UsedMemory *pre_alloc;

  /**

   * if block have less memory it will be put in 'used' list 

   */

  size_t min_malloc;

  size_t block_size;         ///< initial block size

  unsigned int block_num;    ///< allocated blocks counter 

  /**

   * first free block in queue test counter (if it exceed

   * MAX_BLOCK_USAGE_BEFORE_DROP block will be dropped in 'used' list)

   */

  unsigned int first_block_usage;

  void reset_defaults(size_t block_size, size_t prealloc_size);

  unsigned char* alloc(size_t Size);

  void mark_blocks_free();

  void* memdup(const void*, size_t);

  char* strdup(const char*);

  char* strdup(const char*, size_t);

  char* strdup(str_ref);

  void init(size_t block_size= ROOT_MIN_BLOCK_SIZE);

  bool alloc_root_inited() const

  {

    return min_malloc != 0;

  }

  void free_root(myf MyFLAGS);

  void* multi_alloc(int unused, ...);

  void* calloc(size_t size)

  {

    void* ptr= alloc(size);

    memset(ptr, 0, size);

    return ptr;

  }

};

} /* namespace memory */

} /* namespace drizzled */

inline void* operator new(size_t size, drizzled::memory::Root& root)

{

  return root.alloc(size);

}

inline void* operator new[](size_t size, drizzled::memory::Root& root)

{

  return root.alloc(size);

}

inline void operator delete(void*, drizzled::memory::Root&)

{

}

inline void operator delete[](void*, drizzled::memory::Root&)

{

}