mariadb/storage/innobase/include/read0read.ic

/*****************************************************************************

Copyright (c) 1997, 2012, Oracle and/or its affiliates. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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this program; if not, write to the Free Software Foundation, Inc.,
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*****************************************************************************/

/**************************************************//**
@file include/read0read.ic
Cursor read

Created 2/16/1997 Heikki Tuuri
*******************************************************/

#include "trx0sys.h"

#ifdef UNIV_DEBUG
/*********************************************************************//**
Validates a read view object. */
static
bool
read_view_validate(
/*===============*/
	const read_view_t*	view)	/*!< in: view to validate */
{
	ut_ad(mutex_own(&trx_sys->mutex));

	/* Check that the view->trx_ids array is in descending order. */
	for (ulint i = 1; i < view->n_trx_ids; ++i) {

		ut_a(view->trx_ids[i] < view->trx_ids[i - 1]);
	}

	return(true);
}

/** Functor to validate the view list. */
struct	ViewCheck {

	ViewCheck() : m_prev_view(0) { }

	void	operator()(const read_view_t* view)
	{
		ut_a(m_prev_view == NULL
		     || m_prev_view->low_limit_no >= view->low_limit_no);

		m_prev_view = view;
	}

	const read_view_t*	m_prev_view;
};

/*********************************************************************//**
Validates a read view list. */
static
bool
read_view_list_validate(void)
/*=========================*/
{
	ut_ad(mutex_own(&trx_sys->mutex));

	ut_list_map(trx_sys->view_list, &read_view_t::view_list, ViewCheck());

	return(true);
}
#endif /* UNIV_DEBUG */

/*********************************************************************//**
Checks if a read view sees the specified transaction.
@return	true if sees */
UNIV_INLINE
bool
read_view_sees_trx_id(
/*==================*/
	const read_view_t*	view,	/*!< in: read view */
	trx_id_t		trx_id)	/*!< in: trx id */
{
	if (trx_id < view->up_limit_id) {

		return(true);
	} else if (trx_id >= view->low_limit_id) {

		return(false);
	} else {
		ulint	lower = 0;
		ulint	upper = view->n_trx_ids - 1;

		ut_a(view->n_trx_ids > 0);

		do {
			ulint		mid	= (lower + upper) >> 1;
			trx_id_t	mid_id	= view->trx_ids[mid];

			if (mid_id == trx_id) {
				return(FALSE);
			} else if (mid_id < trx_id) {
				if (mid > 0) {
					upper = mid - 1;
				} else {
					break;
				}
			} else {
				lower = mid + 1;
			}
		} while (lower <= upper);
	}

	return(true);
}

/*********************************************************************//**
Remove a read view from the trx_sys->view_list. */
UNIV_INLINE
void
read_view_remove(
/*=============*/
	read_view_t*	view,		/*!< in: read view, can be 0 */
	bool		own_mutex)	/*!< in: true if caller owns the
					trx_sys_t::mutex */
{
	if (view != 0) {
		if (!own_mutex) {
			mutex_enter(&trx_sys->mutex);
		}

		ut_ad(read_view_validate(view));

		UT_LIST_REMOVE(view_list, trx_sys->view_list, view);

		ut_ad(read_view_list_validate());

		if (!own_mutex) {
			mutex_exit(&trx_sys->mutex);
		}
	}
}