~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2002, 2004-2006 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 */

/* Write a record to heap-databas */

#include "heap_priv.h"

#ifdef __WIN__

#include <fcntl.h>

#endif

#include <drizzled/error_t.h>

#define LOWFIND 1

#define LOWUSED 2

#define HIGHFIND 4

#define HIGHUSED 8

using namespace drizzled;

static HASH_INFO *hp_find_free_hash(HP_SHARE *info, HP_BLOCK *block,

				     uint32_t records);

int heap_write(HP_INFO *info, const unsigned char *record)

{

  HP_KEYDEF *keydef, *end;

  unsigned char *pos;

  HP_SHARE *share=info->getShare();

  if ((share->records >= share->max_records && share->max_records) ||

    (share->recordspace.total_data_length + share->index_length >= share->max_table_size))

  {

    return(errno=HA_ERR_RECORD_FILE_FULL);

  }

  if (!(pos=hp_allocate_chunkset(&share->recordspace, 1)))

    return(errno);

  share->changed=1;

  for (keydef = share->keydef, end = keydef + share->keys; keydef < end;

       keydef++)

  {

    if (hp_write_key(info, keydef, record, pos))

      goto err;

  }

  hp_copy_record_data_to_chunkset(share, record, pos);

  if (++share->records == share->blength)

    share->blength+= share->blength;

  info->current_ptr=pos;

  info->current_hash_ptr=0;

  info->update|=HA_STATE_AKTIV;

  if (share->auto_key)

    heap_update_auto_increment(info, record);

  return(0);

err:

  info->errkey= keydef - share->keydef;

  while (keydef >= share->keydef)

  {

    if (hp_delete_key(info, keydef, record, pos, 0))

      break;

    keydef--;

  }

  hp_free_chunks(&share->recordspace, pos);

  return(errno);

} /* heap_write */

/*

  Write a hash-key to the hash-index

  SYNOPSIS

    info     Heap table info

    keyinfo  Key info

    record   Table record to added

    recpos   Memory buffer where the table record will be stored if added

             successfully

  NOTE

    Hash index uses HP_BLOCK structure as a 'growable array' of HASH_INFO

    structs. Array size == number of entries in hash index.

    hp_mask(hp_rec_hashnr()) maps hash entries values to hash array positions.

    If there are several hash entries with the same hash array position P,

    they are connected in a linked list via HASH_INFO::next_key. The first

    list element is located at position P, next elements are located at

    positions for which there is no record that should be located at that

    position. The order of elements in the list is arbitrary.

  RETURN

    0  - OK

    -1 - Out of memory

    HA_ERR_FOUND_DUPP_KEY - Duplicate record on unique key. The record was

    still added and the caller must call hp_delete_key for it.

*/

int hp_write_key(HP_INFO *info, HP_KEYDEF *keyinfo,

		 const unsigned char *record, unsigned char *recpos)

{

  HP_SHARE *share = info->getShare();

  int flag;

  uint32_t halfbuff,hashnr,first_index;

  unsigned char *ptr_to_rec= NULL,*ptr_to_rec2= NULL;

  HASH_INFO *empty, *gpos= NULL, *gpos2= NULL, *pos;

  flag=0;

  if (!(empty= hp_find_free_hash(share,&keyinfo->block,share->records)))

    return(-1);				/* No more memory */

  halfbuff= (long) share->blength >> 1;

  pos= hp_find_hash(&keyinfo->block,(first_index=share->records-halfbuff));

  /*

    We're about to add one more hash array position, with hash_mask=#records.

    The number of hash positions will change and some entries might need to

    be relocated to the newly added position. Those entries are currently

    members of the list that starts at #first_index position (this is

    guaranteed by properties of hp_mask(hp_rec_hashnr(X)) mapping function)

    At #first_index position currently there may be either:

    a) An entry with hashnr != first_index. We don't need to move it.

    or

    b) A list of items with hash_mask=first_index. The list contains entries

       of 2 types:

       1) entries that should be relocated to the list that starts at new

          position we're adding ('uppper' list)

       2) entries that should be left in the list starting at #first_index

          position ('lower' list)

  */

  if (pos != empty)				/* If some records */

  {

    do

    {

      hashnr = hp_rec_hashnr(keyinfo, pos->ptr_to_rec);

      if (flag == 0)

      {

        /*

          First loop, bail out if we're dealing with case a) from above

          comment

        */

	if (hp_mask(hashnr, share->blength, share->records) != first_index)

	  break;

      }

      /*

        flag & LOWFIND - found a record that should be put into lower position

        flag & LOWUSED - lower position occupied by the record

        Same for HIGHFIND and HIGHUSED and 'upper' position

        gpos  - ptr to last element in lower position's list

        gpos2 - ptr to last element in upper position's list

        ptr_to_rec - ptr to last entry that should go into lower list.

        ptr_to_rec2 - same for upper list.

      */

      if (!(hashnr & halfbuff))

      {

        /* Key should be put into 'lower' list */

	if (!(flag & LOWFIND))

	{

          /* key is the first element to go into lower position */

	  if (flag & HIGHFIND)

	  {

	    flag=LOWFIND | HIGHFIND;

	    /* key shall be moved to the current empty position */

	    gpos=empty;

	    ptr_to_rec=pos->ptr_to_rec;

	    empty=pos;				/* This place is now free */

	  }

	  else

	  {

            /*

              We can only get here at first iteration: key is at 'lower'

              position pos and should be left here.

            */

	    flag=LOWFIND | LOWUSED;

	    gpos=pos;

	    ptr_to_rec=pos->ptr_to_rec;

	  }

	}

	else

        {

          /* Already have another key for lower position */

	  if (!(flag & LOWUSED))

	  {

	    /* Change link of previous lower-list key */

	    gpos->ptr_to_rec=ptr_to_rec;

	    gpos->next_key=pos;

	    flag= (flag & HIGHFIND) | (LOWFIND | LOWUSED);

	  }

	  gpos=pos;

	  ptr_to_rec=pos->ptr_to_rec;

	}

      }

      else

      {

        /* key will be put into 'higher' list */

	if (!(flag & HIGHFIND))

	{

	  flag= (flag & LOWFIND) | HIGHFIND;

	  /* key shall be moved to the last (empty) position */

	  gpos2= empty;

          empty= pos;

	  ptr_to_rec2=pos->ptr_to_rec;

	}

	else

	{

	  if (!(flag & HIGHUSED))

	  {

	    /* Change link of previous upper-list key and save */

	    gpos2->ptr_to_rec=ptr_to_rec2;

	    gpos2->next_key=pos;

	    flag= (flag & LOWFIND) | (HIGHFIND | HIGHUSED);

	  }

	  gpos2=pos;

	  ptr_to_rec2=pos->ptr_to_rec;

	}

      }

    }

    while ((pos=pos->next_key));

    if ((flag & (LOWFIND | HIGHFIND)) == (LOWFIND | HIGHFIND))

    {

      /*

        If both 'higher' and 'lower' list have at least one element, now

        there are two hash buckets instead of one.

      */

      keyinfo->hash_buckets++;

    }

    if ((flag & (LOWFIND | LOWUSED)) == LOWFIND)

    {

      gpos->ptr_to_rec=ptr_to_rec;

      gpos->next_key=0;

    }

    if ((flag & (HIGHFIND | HIGHUSED)) == HIGHFIND)

    {

      gpos2->ptr_to_rec=ptr_to_rec2;

      gpos2->next_key=0;

    }

  }

  /* Check if we are at the empty position */

  pos=hp_find_hash(&keyinfo->block, hp_mask(hp_rec_hashnr(keyinfo, record),

					 share->blength, share->records + 1));

  if (pos == empty)

  {

    pos->ptr_to_rec=recpos;

    pos->next_key=0;

    keyinfo->hash_buckets++;

  }

  else

  {

    /* Check if more records in same hash-nr family */

    empty[0]=pos[0];

    gpos=hp_find_hash(&keyinfo->block,

		      hp_mask(hp_rec_hashnr(keyinfo, pos->ptr_to_rec),

			      share->blength, share->records + 1));

    if (pos == gpos)

    {

      pos->ptr_to_rec=recpos;

      pos->next_key=empty;

    }

    else

    {

      keyinfo->hash_buckets++;

      pos->ptr_to_rec=recpos;

      pos->next_key=0;

      hp_movelink(pos, gpos, empty);

    }

    /* Check if duplicated keys */

    if ((keyinfo->flag & HA_NOSAME) && pos == gpos &&

	(!(keyinfo->flag & HA_NULL_PART_KEY) ||

	 !hp_if_null_in_key(keyinfo, record)))

    {

      pos=empty;

      do

      {

	if (! hp_rec_key_cmp(keyinfo, record, pos->ptr_to_rec, 1))

	{

	  return(errno=HA_ERR_FOUND_DUPP_KEY);

	}

      } while ((pos=pos->next_key));

    }

  }

  return(0);

}

	/* Returns ptr to block, and allocates block if neaded */

static HASH_INFO *hp_find_free_hash(HP_SHARE *info,

				     HP_BLOCK *block, uint32_t records)

{

  uint32_t block_pos;

  size_t length;

  if (records < block->last_allocated)

    return hp_find_hash(block,records);

  if (!(block_pos=(records % block->records_in_block)))

  {

    if (hp_get_new_block(block,&length))

      return(NULL);

    info->index_length+=length;

  }

  block->last_allocated=records+1;

  return((HASH_INFO*) ((unsigned char*) block->level_info[0].last_blocks+

		       block_pos*block->recbuffer));

}