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

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

#include "mtr0log.h"
#include "srv0srv.h"
#include "trx0purge.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(space_id_t space, page_no_t 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(space_id_t space, page_no_t 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
page_no_t 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 */
    page_no_t 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;
  page_no_t 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);
}

/** Convert a 7-bit ID stored in a rollback pointer to an undo space ID.
Before 8.0, this ID is called an rseg_id and is a slot in the TRX_SYS page
where the space_id can be read.
After 8.0 this is an undo space number which can be converted directly to
an undo space ID.
@param[in]	id		a 7-bit ID from a rollback pointer
@param[in]	is_temp		true if rseg from Temp Tablespace else false.
@return undo tablespace ID containing the rollback segment */
inline space_id_t trx_rseg_id_to_space_id(ulint id, bool is_temp) {
  /* The rseg_id must be an undo_space_num between 0 and 127. */
  ut_ad(id < TRX_SYS_N_RSEGS);

  /*  MySQL versions before v5.7.2 used the first 32 slots in the
  TRX_SYS page for redo rollback segments. v5.7.2 uses these seg_ids
  for no-redo rollback segments in the temporary tablespace.
  v8 will once again use them for durable/redo rollback segments. */
  if (is_temp) {
    return (srv_tmp_space.space_id());
  }

  /* If the ID is 0 then use the system tablespace. */
  if (id == 0) {
    return (TRX_SYS_SPACE);
  }

  if (srv_upgrade_old_undo_found) {
    /* Interpret the id as a slot in the TRX_SYS page. */
    trx_rseg_t *rseg = trx_sys->rsegs.find(id);
    return (rseg->space_id);
  }

  /* We assume at this point that all undo tablespaces have
  reserved space_ids and RSEG_ARRAY pages. */
  ut_ad(!undo::spaces->empty());

  /* The space_id_bank for this slot cannot change since this call is done
  by purge or MVCC. This space_id can only change during truncate when
  there are no more undo logs in this undo tablespace. */
  space_id_t space_id = undo::num2id(static_cast<space_id_t>(id));
  ut_ad(space_id != SPACE_UNKNOWN);

  return (space_id);
}

/** Get a pointer to the rollback segment directory header and x-latches its
page.
@param[in]	space_id	Undo Tablespace ID
@param[in]	mtr		mtr
@return pointer to rollback segment directory header with page x-latched. */
inline trx_rsegsf_t *trx_rsegsf_get(space_id_t space_id, mtr_t *mtr) {
  buf_block_t *block;
  trx_rsegsf_t *rsegs_header;

  ut_ad(mtr != nullptr);
  ut_ad(undo::is_reserved(space_id));

  block = buf_page_get(page_id_t(space_id, FSP_RSEG_ARRAY_PAGE_NO),
                       univ_page_size, RW_X_LATCH, mtr);
  buf_block_dbg_add_level(block, SYNC_RSEG_ARRAY_HEADER);

  rsegs_header = RSEG_ARRAY_HEADER + buf_block_get_frame(block);

  return (rsegs_header);
}

/** Get the page number of the nth rollback segment slot in the
RSEG_ARRAY page for this undo tablespace.
@param[in]	rsegs_header	rollback segment array page header
@param[in]	slot		slot index == rseg id
@param[in]	mtr		mtr
@return page number, FIL_NULL if slot unused */
inline page_no_t trx_rsegsf_get_page_no(trx_rsegsf_t *rsegs_header, ulint slot,
                                        mtr_t *mtr) {
  ut_ad(rsegs_header != nullptr);
  ut_ad(mtr != nullptr);
  ut_ad(slot < FSP_MAX_ROLLBACK_SEGMENTS);

  return (mtr_read_ulint(
      rsegs_header + RSEG_ARRAY_PAGES_OFFSET + slot * RSEG_ARRAY_SLOT_SIZE,
      MLOG_4BYTES, mtr));
}

/** Sets the page number of the nth rollback segment slot in the
independent undo tablespace.
@param[in]	rsegs_header	rollback segment array page header
@param[in]	slot		slot number on page  == rseg id
@param[in]	page_no		rollback regment header page number
@param[in]	mtr		mtr */
UNIV_INLINE
void trx_rsegsf_set_page_no(trx_rsegsf_t *rsegs_header, ulint slot,
                            page_no_t page_no, mtr_t *mtr) {
  ut_ad(rsegs_header);

  mlog_write_ulint(
      rsegs_header + RSEG_ARRAY_PAGES_OFFSET + slot * RSEG_ARRAY_SLOT_SIZE,
      page_no, MLOG_4BYTES, mtr);
}