~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2006 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/**
  @file

  @brief
  Functions for easy reading of records, possible through a cache
*/
#include "config.h"
#include "drizzled/error.h"
#include "drizzled/table.h"
#include "drizzled/session.h"
#include "drizzled/records.h"
#include "drizzled/optimizer/range.h"
#include "drizzled/internal/my_sys.h"
#include "drizzled/internal/iocache.h"

namespace drizzled
{

int rr_sequential(READ_RECORD *info);
static int rr_quick(READ_RECORD *info);
static int rr_from_tempfile(READ_RECORD *info);
static int rr_unpack_from_tempfile(READ_RECORD *info);
static int rr_unpack_from_buffer(READ_RECORD *info);
static int rr_from_pointers(READ_RECORD *info);
static int rr_from_cache(READ_RECORD *info);
static int init_rr_cache(Session *session, READ_RECORD *info);
static int rr_cmp(unsigned char *a,unsigned char *b);
static int rr_index_first(READ_RECORD *info);
static int rr_index(READ_RECORD *info);

void init_read_record_idx(READ_RECORD *info, 
                          Session *, 
                          Table *table,
                          bool print_error, 
                          uint32_t idx)
{
  table->emptyRecord();
  memset(info, 0, sizeof(*info));
  info->table= table;
  info->cursor=  table->cursor;
  info->record= table->record[0];
  info->print_error= print_error;

  table->status=0;			/* And it's always found */
  if (!table->cursor->inited)
    table->cursor->ha_index_init(idx, 1);
  /* read_record will be changed to rr_index in rr_index_first */
  info->read_record= rr_index_first;
}


void init_read_record(READ_RECORD *info,
                      Session *session, 
                      Table *table,
                      optimizer::SqlSelect *select,
                      int use_record_cache, 
                      bool print_error)
{
  internal::IO_CACHE *tempfile;

  memset(info, 0, sizeof(*info));
  info->session=session;
  info->table=table;
  info->cursor= table->cursor;
  info->forms= &info->table;		/* Only one table */

  if (table->sort.addon_field)
  {
    info->rec_buf= table->sort.addon_buf;
    info->ref_length= table->sort.addon_length;
  }
  else
  {
    table->emptyRecord();
    info->record= table->record[0];
    info->ref_length= table->cursor->ref_length;
  }
  info->select=select;
  info->print_error= print_error;
  info->ignore_not_found_rows= 0;
  table->status=0;			/* And it's always found */

  if (select && my_b_inited(select->file))
    tempfile= select->file;
  else
    tempfile= table->sort.io_cache;
  if (tempfile && my_b_inited(tempfile)) // Test if ref-records was used
  {
    info->read_record= (table->sort.addon_field ?
                        rr_unpack_from_tempfile : rr_from_tempfile);
    info->io_cache=tempfile;
    reinit_io_cache(info->io_cache,internal::READ_CACHE,0L,0,0);
    info->ref_pos=table->cursor->ref;
    if (!table->cursor->inited)
      table->cursor->ha_rnd_init(0);

    /*
      table->sort.addon_field is checked because if we use addon fields,
      it doesn't make sense to use cache - we don't read from the table
      and table->sort.io_cache is read sequentially
    */
    if (!table->sort.addon_field &&
        session->variables.read_rnd_buff_size &&
        !(table->cursor->getEngine()->check_flag(HTON_BIT_FAST_KEY_READ)) &&
        (table->db_stat & HA_READ_ONLY ||
        table->reginfo.lock_type <= TL_READ_NO_INSERT) &&
        (uint64_t) table->s->reclength* (table->cursor->stats.records+
                                                table->cursor->stats.deleted) >
        (uint64_t) MIN_FILE_LENGTH_TO_USE_ROW_CACHE &&
        info->io_cache->end_of_file/info->ref_length * table->s->reclength >
        (internal::my_off_t) MIN_ROWS_TO_USE_TABLE_CACHE &&
        !table->s->blob_fields &&
        info->ref_length <= MAX_REFLENGTH)
    {
      if (! init_rr_cache(session, info))
      {
        info->read_record=rr_from_cache;
      }
    }
  }
  else if (select && select->quick)
  {
    info->read_record=rr_quick;
  }
  else if (table->sort.record_pointers)
  {
    table->cursor->ha_rnd_init(0);
    info->cache_pos=table->sort.record_pointers;
    info->cache_end=info->cache_pos+
                    table->sort.found_records*info->ref_length;
    info->read_record= (table->sort.addon_field ?
                        rr_unpack_from_buffer : rr_from_pointers);
  }
  else
  {
    info->read_record= rr_sequential;
    table->cursor->ha_rnd_init(1);
    /* We can use record cache if we don't update dynamic length tables */
    if (!table->no_cache &&
        (use_record_cache > 0 ||
        (int) table->reginfo.lock_type <= (int) TL_READ_WITH_SHARED_LOCKS ||
        !(table->s->db_options_in_use & HA_OPTION_PACK_RECORD)))
      table->cursor->extra_opt(HA_EXTRA_CACHE, session->variables.read_buff_size);
  }

  return;
} /* init_read_record */


void end_read_record(READ_RECORD *info)
{                   /* free cache if used */
  if (info->cache)
  {
    free((char*) info->cache);
    info->cache=0;
  }
  if (info->table)
  {
    info->table->filesort_free_buffers();
    (void) info->cursor->extra(HA_EXTRA_NO_CACHE);
    if (info->read_record != rr_quick) // otherwise quick_range does it
      (void) info->cursor->ha_index_or_rnd_end();
    info->table=0;
  }
}

static int rr_handle_error(READ_RECORD *info, int error)
{
  if (error == HA_ERR_END_OF_FILE)
    error= -1;
  else
  {
    if (info->print_error)
      info->table->print_error(error, MYF(0));
    if (error < 0)                            // Fix negative BDB errno
      error= 1;
  }
  return error;
}

/** Read a record from head-database. */
static int rr_quick(READ_RECORD *info)
{
  int tmp;
  while ((tmp= info->select->quick->get_next()))
  {
    if (info->session->killed)
    {
      my_error(ER_SERVER_SHUTDOWN, MYF(0));
      return 1;
    }
    if (tmp != HA_ERR_RECORD_DELETED)
    {
      tmp= rr_handle_error(info, tmp);
      break;
    }
  }

  return tmp;
}

/**
  Reads first row in an index scan.

  @param info  	Scan info

  @retval
    0   Ok
  @retval
    -1   End of records
  @retval
    1   Error
*/
static int rr_index_first(READ_RECORD *info)
{
  int tmp= info->cursor->index_first(info->record);
  info->read_record= rr_index;
  if (tmp)
    tmp= rr_handle_error(info, tmp);
  return tmp;
}

/**
  Reads index sequentially after first row.

  Read the next index record (in forward direction) and translate return
  value.

  @param info  Scan info

  @retval
    0   Ok
  @retval
    -1   End of records
  @retval
    1   Error
*/
static int rr_index(READ_RECORD *info)
{
  int tmp= info->cursor->index_next(info->record);
  if (tmp)
    tmp= rr_handle_error(info, tmp);
  return tmp;
}

int rr_sequential(READ_RECORD *info)
{
  int tmp;
  while ((tmp= info->cursor->rnd_next(info->record)))
  {
    if (info->session->killed)
    {
      info->session->send_kill_message();
      return 1;
    }
    /*
      TODO> Fix this so that engine knows how to behave on its own.
      rnd_next can return RECORD_DELETED for MyISAM when one thread is
      reading and another deleting without locks.
    */
    if (tmp != HA_ERR_RECORD_DELETED)
    {
      tmp= rr_handle_error(info, tmp);
      break;
    }
  }

  return tmp;
}

static int rr_from_tempfile(READ_RECORD *info)
{
  int tmp;
  for (;;)
  {
    if (my_b_read(info->io_cache,info->ref_pos,info->ref_length))
      return -1;					/* End of cursor */
    if (!(tmp=info->cursor->rnd_pos(info->record,info->ref_pos)))
      break;
    /* The following is extremely unlikely to happen */
    if (tmp == HA_ERR_RECORD_DELETED ||
        (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
      continue;
    tmp= rr_handle_error(info, tmp);
    break;
  }
  return tmp;
} /* rr_from_tempfile */

/**
  Read a result set record from a temporary cursor after sorting.

  The function first reads the next sorted record from the temporary cursor.
  into a buffer. If a success it calls a callback function that unpacks
  the fields values use in the result set from this buffer into their
  positions in the regular record buffer.

  @param info          Reference to the context including record descriptors

  @retval
    0   Record successfully read.
  @retval
    -1   There is no record to be read anymore.
*/
static int rr_unpack_from_tempfile(READ_RECORD *info)
{
  if (my_b_read(info->io_cache, info->rec_buf, info->ref_length))
    return -1;
  Table *table= info->table;
  (*table->sort.unpack)(table->sort.addon_field, info->rec_buf);

  return 0;
}

static int rr_from_pointers(READ_RECORD *info)
{
  int tmp;
  unsigned char *cache_pos;

  for (;;)
  {
    if (info->cache_pos == info->cache_end)
      return -1;					/* End of cursor */
    cache_pos= info->cache_pos;
    info->cache_pos+= info->ref_length;

    if (!(tmp=info->cursor->rnd_pos(info->record,cache_pos)))
      break;

    /* The following is extremely unlikely to happen */
    if (tmp == HA_ERR_RECORD_DELETED ||
        (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
      continue;
    tmp= rr_handle_error(info, tmp);
    break;
  }
  return tmp;
}

/**
  Read a result set record from a buffer after sorting.

  The function first reads the next sorted record from the sort buffer.
  If a success it calls a callback function that unpacks
  the fields values use in the result set from this buffer into their
  positions in the regular record buffer.

  @param info          Reference to the context including record descriptors

  @retval
    0   Record successfully read.
  @retval
    -1   There is no record to be read anymore.
*/
static int rr_unpack_from_buffer(READ_RECORD *info)
{
  if (info->cache_pos == info->cache_end)
    return -1;                      /* End of buffer */
  Table *table= info->table;
  (*table->sort.unpack)(table->sort.addon_field, info->cache_pos);
  info->cache_pos+= info->ref_length;

  return 0;
}

/* cacheing of records from a database */
static int init_rr_cache(Session *session, READ_RECORD *info)
{
  uint32_t rec_cache_size;

  info->struct_length= 3+MAX_REFLENGTH;
  info->reclength= ALIGN_SIZE(info->table->s->reclength+1);
  if (info->reclength < info->struct_length)
    info->reclength= ALIGN_SIZE(info->struct_length);

  info->error_offset= info->table->s->reclength;
  info->cache_records= (session->variables.read_rnd_buff_size /
                        (info->reclength+info->struct_length));
  rec_cache_size= info->cache_records*info->reclength;
  info->rec_cache_size= info->cache_records*info->ref_length;

  // We have to allocate one more byte to use uint3korr (see comments for it)
  if (info->cache_records <= 2 ||
      !(info->cache=(unsigned char*) malloc(rec_cache_size+info->cache_records*
					    info->struct_length+1)))
    return(1);
#ifdef HAVE_purify
  // Avoid warnings in qsort
  memset(info->cache, 0,
         rec_cache_size+info->cache_records* info->struct_length+1);
#endif
  info->read_positions=info->cache+rec_cache_size;
  info->cache_pos=info->cache_end=info->cache;
  return(0);
} /* init_rr_cache */

static int rr_from_cache(READ_RECORD *info)
{
  register uint32_t i;
  uint32_t length;
  internal::my_off_t rest_of_file;
  int16_t error;
  unsigned char *position,*ref_position,*record_pos;
  uint32_t record;

  for (;;)
  {
    if (info->cache_pos != info->cache_end)
    {
      if (info->cache_pos[info->error_offset])
      {
        shortget(error,info->cache_pos);
        if (info->print_error)
          info->table->print_error(error,MYF(0));
      }
      else
      {
        error=0;
        memcpy(info->record,info->cache_pos, (size_t) info->table->s->reclength);
      }
      info->cache_pos+=info->reclength;
      return ((int) error);
    }
    length=info->rec_cache_size;
    rest_of_file=info->io_cache->end_of_file - my_b_tell(info->io_cache);
    if ((internal::my_off_t) length > rest_of_file)
      length= (uint32_t) rest_of_file;
    if (!length || my_b_read(info->io_cache,info->cache,length))
    {
      return -1;			/* End of cursor */
    }

    length/=info->ref_length;
    position=info->cache;
    ref_position=info->read_positions;
    for (i=0 ; i < length ; i++,position+=info->ref_length)
    {
      memcpy(ref_position,position,(size_t) info->ref_length);
      ref_position+=MAX_REFLENGTH;
      int3store(ref_position,(long) i);
      ref_position+=3;
    }
    internal::my_qsort(info->read_positions, length, info->struct_length,
                       (qsort_cmp) rr_cmp);

    position=info->read_positions;
    for (i=0 ; i < length ; i++)
    {
      memcpy(info->ref_pos,position,(size_t) info->ref_length);
      position+=MAX_REFLENGTH;
      record=uint3korr(position);
      position+=3;
      record_pos=info->cache+record*info->reclength;
      if ((error=(int16_t) info->cursor->rnd_pos(record_pos,info->ref_pos)))
      {
        record_pos[info->error_offset]=1;
        shortstore(record_pos,error);
      }
      else
        record_pos[info->error_offset]=0;
    }
    info->cache_end=(info->cache_pos=info->cache)+length*info->reclength;
  }
} /* rr_from_cache */

static int rr_cmp(unsigned char *a,unsigned char *b)
{
  if (a[0] != b[0])
    return (int) a[0] - (int) b[0];
  if (a[1] != b[1])
    return (int) a[1] - (int) b[1];
  if (a[2] != b[2])
    return (int) a[2] - (int) b[2];
#if MAX_REFLENGTH == 4
  return (int) a[3] - (int) b[3];
#else
  if (a[3] != b[3])
    return (int) a[3] - (int) b[3];
  if (a[4] != b[4])
    return (int) a[4] - (int) b[4];
  if (a[5] != b[5])
    return (int) a[1] - (int) b[5];
  if (a[6] != b[6])
    return (int) a[6] - (int) b[6];
  return (int) a[7] - (int) b[7];
#endif
}

} /* namespace drizzled */