~drizzle-trunk/drizzle/development

/* Copyright (C) 2003, 2005 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*

  Preload indexes into key cache

*/

#include "myisam_priv.h"

#include <stdlib.h>

#include <drizzled/util/test.h>

using namespace drizzled;

/*

  Preload pages of the index file for a table into the key cache

  SYNOPSIS

    mi_preload()

      info          open table

      map           map of indexes to preload into key cache

      ignore_leaves only non-leaves pages are to be preloaded

  RETURN VALUE

    0 if a success. error code - otherwise.

  NOTES.

    At present pages for all indexes are preloaded.

    In future only pages for indexes specified in the key_map parameter

    of the table will be preloaded.

*/

int mi_preload(MI_INFO *info, uint64_t key_map, bool ignore_leaves)

{

  uint32_t i;

  uint32_t length, block_length= 0;

  unsigned char *buff= NULL;

  MYISAM_SHARE* share= info->s;

  uint32_t keys= share->state.header.keys;

  MI_KEYDEF *keyinfo= share->keyinfo;

  internal::my_off_t key_file_length= share->state.state.key_file_length;

  internal::my_off_t pos= share->base.keystart;

  if (!keys || !mi_is_any_key_active(key_map) || key_file_length == pos)

    return(0);

  block_length= keyinfo[0].block_length;

  if (ignore_leaves)

  {

    /* Check whether all indexes use the same block size */

    for (i= 1 ; i < keys ; i++)

    {

      if (keyinfo[i].block_length != block_length)

        return(errno= HA_ERR_NON_UNIQUE_BLOCK_SIZE);

    }

  }

  else

    block_length= share->key_cache->key_cache_block_size;

  length= info->preload_buff_size/block_length * block_length;

  set_if_bigger(length, block_length);

  if (!(buff= (unsigned char *) malloc(length)))

    return(errno= HA_ERR_OUT_OF_MEM);

  if (flush_key_blocks(share->key_cache,share->kfile, FLUSH_RELEASE))

    goto err;

  do

  {

    /* Read the next block of index file into the preload buffer */

    if ((internal::my_off_t) length > (key_file_length-pos))

      length= (uint32_t) (key_file_length-pos);

    if (my_pread(share->kfile, (unsigned char*) buff, length, pos, MYF(MY_FAE|MY_FNABP)))

      goto err;

    if (ignore_leaves)

    {

      unsigned char *end= buff+length;

      do

      {

        if (mi_test_if_nod(buff))

        {

          if (key_cache_insert(share->key_cache,

                               share->kfile, pos, DFLT_INIT_HITS,

                              (unsigned char*) buff, block_length))

	    goto err;

	}

        pos+= block_length;

      }

      while ((buff+= block_length) != end);

      buff= end-length;

    }

    else

    {

      if (key_cache_insert(share->key_cache,

                           share->kfile, pos, DFLT_INIT_HITS,

                           (unsigned char*) buff, length))

	goto err;

      pos+= length;

    }

  }

  while (pos != key_file_length);

  free((char*) buff);

  return(0);

err:

  free((char*) buff);

  return(errno= errno);

}