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

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

/**************************************************//**
@file include/trx0rseg.ic
Rollback segment

Created 3/26/1996 Heikki Tuuri
*******************************************************/

#include "srv0srv.h"
#include "mtr0log.h"
#include "trx0sys.h"

/** Gets a rollback segment header.
@param[in]	space		space where placed
@param[in]	page_no		page number of the header
@param[in]	page_size	page size
@param[in,out]	mtr		mini-transaction
@return rollback segment header, page x-latched */
UNIV_INLINE
trx_rsegf_t*
trx_rsegf_get(
	ulint			space,
	ulint			page_no,
	const page_size_t&	page_size,
	mtr_t*			mtr)
{
	buf_block_t*	block;
	trx_rsegf_t*	header;

	block = buf_page_get(
		page_id_t(space, page_no), page_size, RW_X_LATCH, mtr);

	buf_block_dbg_add_level(block, SYNC_RSEG_HEADER);

	header = TRX_RSEG + buf_block_get_frame(block);

	return(header);
}

/** Gets a newly created rollback segment header.
@param[in]	space		space where placed
@param[in]	page_no		page number of the header
@param[in]	page_size	page size
@param[in,out]	mtr		mini-transaction
@return rollback segment header, page x-latched */
UNIV_INLINE
trx_rsegf_t*
trx_rsegf_get_new(
	ulint			space,
	ulint			page_no,
	const page_size_t&	page_size,
	mtr_t*			mtr)
{
	buf_block_t*	block;
	trx_rsegf_t*	header;

	block = buf_page_get(
		page_id_t(space, page_no), page_size, RW_X_LATCH, mtr);

	buf_block_dbg_add_level(block, SYNC_RSEG_HEADER_NEW);

	header = TRX_RSEG + buf_block_get_frame(block);

	return(header);
}

/***************************************************************//**
Gets the file page number of the nth undo log slot.
@return page number of the undo log segment */
UNIV_INLINE
ulint
trx_rsegf_get_nth_undo(
/*===================*/
	trx_rsegf_t*	rsegf,	/*!< in: rollback segment header */
	ulint		n,	/*!< in: index of slot */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_a(n < TRX_RSEG_N_SLOTS);

	return(mtr_read_ulint(rsegf + TRX_RSEG_UNDO_SLOTS
			      + n * TRX_RSEG_SLOT_SIZE, MLOG_4BYTES, mtr));
}

/***************************************************************//**
Sets the file page number of the nth undo log slot. */
UNIV_INLINE
void
trx_rsegf_set_nth_undo(
/*===================*/
	trx_rsegf_t*	rsegf,	/*!< in: rollback segment header */
	ulint		n,	/*!< in: index of slot */
	ulint		page_no,/*!< in: page number of the undo log segment */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_a(n < TRX_RSEG_N_SLOTS);

	mlog_write_ulint(rsegf + TRX_RSEG_UNDO_SLOTS + n * TRX_RSEG_SLOT_SIZE,
			 page_no, MLOG_4BYTES, mtr);
}

/****************************************************************//**
Looks for a free slot for an undo log segment.
@return slot index or ULINT_UNDEFINED if not found */
UNIV_INLINE
ulint
trx_rsegf_undo_find_free(
/*=====================*/
	trx_rsegf_t*	rsegf,	/*!< in: rollback segment header */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ulint		i;
	ulint		page_no;
	ulint		max_slots = TRX_RSEG_N_SLOTS;

#ifdef UNIV_DEBUG
	if (trx_rseg_n_slots_debug) {
		max_slots = ut_min(static_cast<ulint>(trx_rseg_n_slots_debug),
				   static_cast<ulint>(TRX_RSEG_N_SLOTS));
	}
#endif

	for (i = 0; i < max_slots; i++) {
		page_no = trx_rsegf_get_nth_undo(rsegf, i, mtr);

		if (page_no == FIL_NULL) {
			return(i);
		}
	}

	return(ULINT_UNDEFINED);
}

/******************************************************************//**
Looks for a rollback segment, based on the rollback segment id.
@return rollback segment */
UNIV_INLINE
trx_rseg_t*
trx_rseg_get_on_id(
/*===============*/
	ulint	id,		/*!< in: rollback segment id */
	bool	is_redo_rseg)	/*!< in: true if redo rseg else false. */
{
	ut_a(id < TRX_SYS_N_RSEGS);

	/* If redo rseg is being requested and id falls in range of
	non-redo rseg that is from slot-1....slot-srv_tmp_undo_logs then
	server is being upgraded from pre-5.7.2. In such case return
	rseg from pending_purge_rseg_array array. */
	if (is_redo_rseg && trx_sys_is_noredo_rseg_slot(id)) {
		ut_ad(trx_sys->pending_purge_rseg_array[id] != NULL);
		return(trx_sys->pending_purge_rseg_array[id]);
	}

	return(trx_sys->rseg_array[id]);
}