Function my_hash_update

mysys/hash.c:612–709

	  */

my_bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
                       size_t old_key_length)
{
  uint new_index,new_pos_index,blength,records;
  size_t idx,empty;
  HASH_LINK org_link,*data,*previous,*pos;
  DBUG_ENTER("my_hash_update");
  
  if (HASH_UNIQUE & hash->flags)
  {
    HASH_SEARCH_STATE state;
    uchar *found, *new_key= (uchar*) my_hash_key(hash, record, &idx, 1);
    if ((found= my_hash_first(hash, new_key, idx, &state)))
    {
      do 
      {
        if (found != record)
          DBUG_RETURN(1);		/* Duplicate entry */
      } 
      while ((found= my_hash_next(hash, new_key, idx, &state)));
    }
  }

  data=dynamic_element(&hash->array,0,HASH_LINK*);
  blength=hash->blength; records=hash->records;

  /* Search after record with key */

  idx= my_hash_mask(calc_hash(hash, old_key, (old_key_length ?
                                              old_key_length :
                                              hash->key_length)),
                    blength, records);
  new_index= my_hash_mask(rec_hashnr(hash, record), blength, records);
  if (idx == new_index)
    DBUG_RETURN(0);			/* Nothing to do (No record check) */
  previous=0;
  for (;;)
  {

    if ((pos= data+idx)->data == record)
      break;
    previous=pos;
    if ((idx=pos->next) == NO_RECORD)
      DBUG_RETURN(1);			/* Not found in links */
  }
  org_link= *pos;
  empty=idx;

  /* Relink record from current chain */

  if (!previous)
  {
    if (pos->next != NO_RECORD)
    {
      empty=pos->next;
      *pos= data[pos->next];
    }
  }