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99 lines
2.7 KiB
Text
99 lines
2.7 KiB
Text
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/*****************************************************************************
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Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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Place, Suite 330, Boston, MA 02111-1307 USA
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*****************************************************************************/
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/**************************************************//**
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@file include/read0read.ic
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Cursor read
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Created 2/16/1997 Heikki Tuuri
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*******************************************************/
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/*********************************************************************//**
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Gets the nth trx id in a read view.
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@return trx id */
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UNIV_INLINE
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trx_id_t
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read_view_get_nth_trx_id(
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/*=====================*/
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const read_view_t* view, /*!< in: read view */
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ulint n) /*!< in: position */
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{
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ut_ad(n < view->n_trx_ids);
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return(*(view->trx_ids + n));
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}
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/*********************************************************************//**
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Sets the nth trx id in a read view. */
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UNIV_INLINE
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void
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read_view_set_nth_trx_id(
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/*=====================*/
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read_view_t* view, /*!< in: read view */
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ulint n, /*!< in: position */
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trx_id_t trx_id) /*!< in: trx id to set */
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{
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ut_ad(n < view->n_trx_ids);
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*(view->trx_ids + n) = trx_id;
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}
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/*********************************************************************//**
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Checks if a read view sees the specified transaction.
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@return TRUE if sees */
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UNIV_INLINE
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ibool
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read_view_sees_trx_id(
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/*==================*/
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const read_view_t* view, /*!< in: read view */
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trx_id_t trx_id) /*!< in: trx id */
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{
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ulint n_ids;
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int cmp;
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ulint i;
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if (ut_dulint_cmp(trx_id, view->up_limit_id) < 0) {
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return(TRUE);
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}
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if (ut_dulint_cmp(trx_id, view->low_limit_id) >= 0) {
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return(FALSE);
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}
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/* We go through the trx ids in the array smallest first: this order
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may save CPU time, because if there was a very long running
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transaction in the trx id array, its trx id is looked at first, and
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the first two comparisons may well decide the visibility of trx_id. */
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n_ids = view->n_trx_ids;
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for (i = 0; i < n_ids; i++) {
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cmp = ut_dulint_cmp(
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trx_id,
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read_view_get_nth_trx_id(view, n_ids - i - 1));
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if (cmp <= 0) {
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return(cmp < 0);
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}
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}
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return(TRUE);
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}
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