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/*****************************************************************************
Copyright (c) 1997, 2009, Innobase Oy. 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
*****************************************************************************/
/**************************************************//**
@file include/read0read.ic
Cursor read
Created 2/16/1997 Heikki Tuuri
*******************************************************/
/*********************************************************************//**
Gets the nth trx id in a read view.
@return trx id */
UNIV_INLINE
trx_id_t
read_view_get_nth_trx_id(
/*=====================*/
const read_view_t* view, /*!< in: read view */
ulint n) /*!< in: position */
{
ut_ad(n < view->n_trx_ids);
return(*(view->trx_ids + n));
}
/*********************************************************************//**
Sets the nth trx id in a read view. */
UNIV_INLINE
void
read_view_set_nth_trx_id(
/*=====================*/
read_view_t* view, /*!< in: read view */
ulint n, /*!< in: position */
trx_id_t trx_id) /*!< in: trx id to set */
{
ut_ad(n < view->n_trx_ids);
*(view->trx_ids + n) = trx_id;
}
/*********************************************************************//**
Checks if a read view sees the specified transaction.
@return TRUE if sees */
UNIV_INLINE
ibool
read_view_sees_trx_id(
/*==================*/
const read_view_t* view, /*!< in: read view */
trx_id_t trx_id) /*!< in: trx id */
{
ulint n_ids;
int cmp;
ulint i;
if (ut_dulint_cmp(trx_id, view->up_limit_id) < 0) {
return(TRUE);
}
if (ut_dulint_cmp(trx_id, view->low_limit_id) >= 0) {
return(FALSE);
}
/* We go through the trx ids in the array smallest first: this order
may save CPU time, because if there was a very long running
transaction in the trx id array, its trx id is looked at first, and
the first two comparisons may well decide the visibility of trx_id. */
n_ids = view->n_trx_ids;
for (i = 0; i < n_ids; i++) {
cmp = ut_dulint_cmp(
trx_id,
read_view_get_nth_trx_id(view, n_ids - i - 1));
if (cmp <= 0) {
return(cmp < 0);
}
}
return(TRUE);
}
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