path: root/sql/rpl_record.cc

/* Copyright 2007 MySQL AB. All rights reserved.

   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 */

#include "mysql_priv.h"
#include "rpl_rli.h"
#include "rpl_record.h"
#include "slave.h"                  // Need to pull in slave_print_msg

/**
   Pack a record of data for a table into a format suitable for
   transfer via the binary log.

   The format for a row in transfer with N fields is the following:

   ceil(N/8) null bytes:
       One null bit for every column *regardless of whether it can be
       null or not*. This simplifies the decoding. Observe that the
       number of null bits is equal to the number of set bits in the
       @c cols bitmap. The number of null bytes is the smallest number
       of bytes necessary to store the null bits.

       Padding bits are 1.

   N packets:
       Each field is stored in packed format.


   @param table    Table describing the format of the record

   @param cols     Bitmap with a set bit for each column that should
                   be stored in the row

   @param row_data Pointer to memory where row will be written

   @param record   Pointer to record that should be packed. It is
                   assumed that the pointer refers to either @c
                   record[0] or @c record[1], but no such check is
                   made since the code does not rely on that.

   @return The number of bytes written at @c row_data.
 */
#if !defined(MYSQL_CLIENT)
size_t
pack_row(TABLE *table, MY_BITMAP const* cols,
         uchar *row_data, const uchar *record)
{
  Field **p_field= table->field, *field;
  int const null_byte_count= (bitmap_bits_set(cols) + 7) / 8;
  uchar *pack_ptr = row_data + null_byte_count;
  uchar *null_ptr = row_data;
  my_ptrdiff_t const rec_offset= record - table->record[0];
  my_ptrdiff_t const def_offset= table->s->default_values - table->record[0];

  /*
    We write the null bits and the packed records using one pass
    through all the fields. The null bytes are written little-endian,
    i.e., the first fields are in the first byte.
   */
  unsigned int null_bits= (1U << 8) - 1;
  // Mask to mask out the correct but among the null bits
  unsigned int null_mask= 1U;
  for ( ; (field= *p_field) ; p_field++)
  {
    DBUG_PRINT("debug", ("null_mask=%d; null_ptr=%p; row_data=%p; null_byte_count=%d",
                         null_mask, null_ptr, row_data, null_byte_count));
    if (bitmap_is_set(cols, p_field - table->field))
    {
      my_ptrdiff_t offset;
      if (field->is_null(rec_offset))
      {
        offset= def_offset;
        null_bits |= null_mask;
      }
      else
      {
        offset= rec_offset;
        null_bits &= ~null_mask;

        /*
          We only store the data of the field if it is non-null
         */
        pack_ptr= field->pack(pack_ptr, field->ptr + offset);
      }

      null_mask <<= 1;
      if ((null_mask & 0xFF) == 0)
      {
        DBUG_ASSERT(null_ptr < row_data + null_byte_count);
        null_mask = 1U;
        *null_ptr++ = null_bits;
        null_bits= (1U << 8) - 1;
      }
    }
  }

  /*
    Write the last (partial) byte, if there is one
  */
  if ((null_mask & 0xFF) > 1)
  {
    DBUG_ASSERT(null_ptr < row_data + null_byte_count);
    *null_ptr++ = null_bits;
  }

  /*
    The null pointer should now point to the first byte of the
    packed data. If it doesn't, something is very wrong.
  */
  DBUG_ASSERT(null_ptr == row_data + null_byte_count);

  return static_cast<size_t>(pack_ptr - row_data);
}
#endif


/**
   Unpack a row into @c table->record[0].

   The function will always unpack into the @c table->record[0]
   record.  This is because there are too many dependencies on where
   the various member functions of Field and subclasses expect to
   write.

   The row is assumed to only consist of the fields for which the
   bitset represented by @c arr and @c bits; the other parts of the
   record are left alone.

   At most @c colcnt columns are read: if the table is larger than
   that, the remaining fields are not filled in.

   @param rli     Relay log info
   @param table   Table to unpack into
   @param colcnt  Number of columns to read from record
   @param row     Packed row data
   @param cols    Pointer to columns data to fill in
   @param row_end Pointer to variable that will hold the value of the
                  one-after-end position for the row
   @param master_reclength
                  Pointer to variable that will be set to the length of the
                  record on the master side
   @param rw_set  Pointer to bitmap that holds either the read_set or the
                  write_set of the table


   @retval 0 No error

   @retval ER_NO_DEFAULT_FOR_FIELD
   Returned if one of the fields existing on the slave but not on the
   master does not have a default value (and isn't nullable)

 */
#if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
int
unpack_row(RELAY_LOG_INFO const *rli,
           TABLE *table, uint const colcnt,
           uchar const *const row_data, MY_BITMAP const *cols,
           uchar const **const row_end, ulong *const master_reclength,
           MY_BITMAP* const rw_set, Log_event_type const event_type)
{
  DBUG_ENTER("unpack_row");
  DBUG_ASSERT(row_data);
  size_t const master_null_byte_count= (bitmap_bits_set(cols) + 7) / 8;
  int error= 0;

  uchar const *null_ptr= row_data;
  uchar const *pack_ptr= row_data + master_null_byte_count;

  bitmap_clear_all(rw_set);

  empty_record(table);

  Field **const begin_ptr = table->field;
  Field **field_ptr;
  Field **const end_ptr= begin_ptr + colcnt;

  DBUG_ASSERT(null_ptr < row_data + master_null_byte_count);

  // Mask to mask out the correct bit among the null bits
  unsigned int null_mask= 1U;
  // The "current" null bits
  unsigned int null_bits= *null_ptr++;
  for (field_ptr= begin_ptr ; field_ptr < end_ptr ; ++field_ptr)
  {
    Field *const f= *field_ptr;

    /*
      No need to bother about columns that does not exist: they have
      gotten default values when being emptied above.
     */
    if (bitmap_is_set(cols, field_ptr -  begin_ptr))
    {
      if ((null_mask & 0xFF) == 0)
      {
        DBUG_ASSERT(null_ptr < row_data + master_null_byte_count);
        null_mask= 1U;
        null_bits= *null_ptr++;
      }

      DBUG_ASSERT(null_mask & 0xFF); // One of the 8 LSB should be set

      /* Field...::unpack() cannot return 0 */
      DBUG_ASSERT(pack_ptr != NULL);

      if ((null_bits & null_mask) && f->maybe_null())
        f->set_null();
      else
      {
        f->set_notnull();

        /*
          We only unpack the field if it was non-null
        */
        pack_ptr= f->unpack(f->ptr, pack_ptr);
      }

      bitmap_set_bit(rw_set, f->field_index);
      null_mask <<= 1;
    }
  }

  /*
    We should now have read all the null bytes, otherwise something is
    really wrong.
   */
  DBUG_ASSERT(null_ptr == row_data + master_null_byte_count);

  *row_end = pack_ptr;
  if (master_reclength)
  {
    if (*field_ptr)
      *master_reclength = (*field_ptr)->ptr - table->record[0];
    else
      *master_reclength = table->s->reclength;
  }

  /*
    Set properties for remaining columns, if there are any. We let the
    corresponding bit in the write_set be set, to write the value if
    it was not there already. We iterate over all remaining columns,
    even if there were an error, to get as many error messages as
    possible.  We are still able to return a pointer to the next row,
    so redo that.

    This generation of error messages is only relevant when inserting
    new rows.
   */
  for ( ; *field_ptr ; ++field_ptr)
  {
    uint32 const mask= NOT_NULL_FLAG | NO_DEFAULT_VALUE_FLAG;
    Field *const f= *field_ptr;

    if (event_type == WRITE_ROWS_EVENT &&
        ((*field_ptr)->flags & mask) == mask)
    {
      rli->report(ERROR_LEVEL, ER_NO_DEFAULT_FOR_FIELD,
                  "Field `%s` of table `%s`.`%s` "
                  "has no default value and cannot be NULL",
                  (*field_ptr)->field_name, table->s->db.str,
                  table->s->table_name.str);
      error = ER_NO_DEFAULT_FOR_FIELD;
    }
    else
      f->set_default();
  }

  DBUG_RETURN(error);
}

#endif // HAVE_REPLICATION