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

/** @file include/trx0sys.ic
 Transaction system

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

#include "data0type.h"
#include "srv0srv.h"
#include "trx0trx.h"
#ifndef UNIV_HOTBACKUP
#include "mtr0log.h"

/* The typedef for rseg slot in the file copy */
typedef byte trx_sysf_rseg_t;

/* Rollback segment specification slot offsets */
/*-------------------------------------------------------------*/
#define TRX_SYS_RSEG_SPACE          \
  0 /* space where the segment      \
    header is placed; starting with \
    MySQL/InnoDB 5.1.7, this is     \
    UNIV_UNDEFINED if the slot is unused */
#define TRX_SYS_RSEG_PAGE_NO           \
  4 /*  page number where the segment  \
    header is placed; this is FIL_NULL \
    if the slot is unused */
/*-------------------------------------------------------------*/
/* Size of a rollback segment specification slot */
#define TRX_SYS_RSEG_SLOT_SIZE 8

/** Writes the value of max_trx_id to the file based trx system header. */
void trx_sys_flush_max_trx_id(void);

/** Checks if a page address is the trx sys header page.
@param[in]	page_id	page id
@return true if trx sys header page */
UNIV_INLINE
bool trx_sys_hdr_page(const page_id_t &page_id) {
  return (page_id.space() == TRX_SYS_SPACE &&
          page_id.page_no() == TRX_SYS_PAGE_NO);
}

/** Gets a pointer to the transaction system header and x-latches its page.
 @return pointer to system header, page x-latched. */
UNIV_INLINE
trx_sysf_t *trx_sysf_get(mtr_t *mtr) /*!< in: mtr */
{
  buf_block_t *block;
  trx_sysf_t *header;

  ut_ad(mtr);

  block = buf_page_get(page_id_t(TRX_SYS_SPACE, TRX_SYS_PAGE_NO),
                       univ_page_size, RW_X_LATCH, mtr);
  buf_block_dbg_add_level(block, SYNC_TRX_SYS_HEADER);

  header = TRX_SYS + buf_block_get_frame(block);

  return (header);
}

/** Gets the space of the nth rollback segment slot in the trx system
 file copy.
 @return space id */
UNIV_INLINE
space_id_t trx_sysf_rseg_get_space(
    trx_sysf_t *sys_header, /*!< in: trx sys header */
    ulint slot,             /*!< in: slot index == rseg id */
    mtr_t *mtr)             /*!< in: mtr */
{
  ut_ad(sys_header);
  ut_ad(slot < TRX_SYS_N_RSEGS);

  return (mtr_read_ulint(sys_header + TRX_SYS_RSEGS +
                             slot * TRX_SYS_RSEG_SLOT_SIZE + TRX_SYS_RSEG_SPACE,
                         MLOG_4BYTES, mtr));
}

/** Gets the page number of the nth rollback segment slot in the trx system
 header.
 @return page number, FIL_NULL if slot unused */
UNIV_INLINE
page_no_t trx_sysf_rseg_get_page_no(
    trx_sysf_t *sys_header, /*!< in: trx system header */
    ulint slot,             /*!< in: slot index == rseg id */
    mtr_t *mtr)             /*!< in: mtr */
{
  ut_ad(sys_header);
  ut_ad(slot < TRX_SYS_N_RSEGS);

  return (mtr_read_ulint(sys_header + TRX_SYS_RSEGS +
                             slot * TRX_SYS_RSEG_SLOT_SIZE +
                             TRX_SYS_RSEG_PAGE_NO,
                         MLOG_4BYTES, mtr));
}

/** Sets the space id of the nth rollback segment slot in the trx system
 file copy. */
UNIV_INLINE
void trx_sysf_rseg_set_space(
    trx_sysf_t *sys_header, /*!< in: trx sys file copy */
    ulint slot,             /*!< in: slot index == rseg id */
    space_id_t space,       /*!< in: space id */
    mtr_t *mtr)             /*!< in: mtr */
{
  ut_ad(sys_header);
  ut_ad(slot < TRX_SYS_N_RSEGS);

  mlog_write_ulint(sys_header + TRX_SYS_RSEGS + slot * TRX_SYS_RSEG_SLOT_SIZE +
                       TRX_SYS_RSEG_SPACE,
                   space, MLOG_4BYTES, mtr);
}

/** Sets the page number of the nth rollback segment slot in the trx system
 header. */
UNIV_INLINE
void trx_sysf_rseg_set_page_no(
    trx_sysf_t *sys_header, /*!< in: trx sys header */
    ulint slot,             /*!< in: slot index == rseg id */
    page_no_t page_no,      /*!< in: page number, FIL_NULL if the
                            slot is reset to unused */
    mtr_t *mtr)             /*!< in: mtr */
{
  ut_ad(sys_header);
  ut_ad(slot < TRX_SYS_N_RSEGS);

  mlog_write_ulint(sys_header + TRX_SYS_RSEGS + slot * TRX_SYS_RSEG_SLOT_SIZE +
                       TRX_SYS_RSEG_PAGE_NO,
                   page_no, MLOG_4BYTES, mtr);
}
#endif /* !UNIV_HOTBACKUP */

/** Writes a trx id to an index page. In case that the id size changes in
 some future version, this function should be used instead of
 mach_write_... */
UNIV_INLINE
void trx_write_trx_id(byte *ptr,   /*!< in: pointer to memory where written */
                      trx_id_t id) /*!< in: id */
{
  ut_ad(id > 0);
  mach_write_to_6(ptr, id);
}

#ifndef UNIV_HOTBACKUP
/** Reads a trx id from an index page. In case that the id size changes in
 some future version, this function should be used instead of
 mach_read_...
 @return id */
UNIV_INLINE
trx_id_t trx_read_trx_id(
    const byte *ptr) /*!< in: pointer to memory from where to read */
{
  return (mach_read_from_6(ptr));
}

/** Looks for the trx handle with the given id in rw_trx_list.
 The caller must be holding trx_sys->mutex.
 @return the trx handle or NULL if not found;
 the pointer must not be dereferenced unless lock_sys->mutex was
 acquired before calling this function and is still being held */
UNIV_INLINE
trx_t *trx_get_rw_trx_by_id(trx_id_t trx_id) /*!< in: trx id to search for */
{
  ut_ad(trx_id > 0);
  ut_ad(trx_sys_mutex_own());

  if (trx_sys->rw_trx_hash.empty()) {
    return (NULL);
  }

  TrxIdHash::iterator it;

  it = trx_sys->rw_trx_hash.find(trx_id);

  return (it == trx_sys->rw_trx_hash.end() ? NULL : it->second);
}

/** Returns the minimum trx id in trx list. This is the smallest id for which
 the trx can possibly be active. (But, you must look at the trx->state
 to find out if the minimum trx id transaction itself is active, or already
 committed.). The caller must be holding the trx_sys_t::mutex in shared mode.
 @return the minimum trx id, or trx_sys->max_trx_id if the trx list is empty */
UNIV_INLINE
trx_id_t trx_rw_min_trx_id_low(void) {
  trx_id_t id;

  ut_ad(trx_sys_mutex_own());

  const trx_t *trx = UT_LIST_GET_LAST(trx_sys->rw_trx_list);

  if (trx == NULL) {
    id = trx_sys->max_trx_id;
  } else {
    assert_trx_in_rw_list(trx);
    id = trx->id;
  }

  return (id);
}

#if defined UNIV_DEBUG || defined UNIV_BLOB_LIGHT_DEBUG
/** Assert that a transaction has been recovered.
 @return true */
UNIV_INLINE
ibool trx_assert_recovered(trx_id_t trx_id) /*!< in: transaction identifier */
{
  const trx_t *trx;

  trx_sys_mutex_enter();

  trx = trx_get_rw_trx_by_id(trx_id);
  ut_a(trx->is_recovered);

  trx_sys_mutex_exit();

  return (TRUE);
}
#endif /* UNIV_DEBUG || UNIV_BLOB_LIGHT_DEBUG */

/** Returns the minimum trx id in rw trx list. This is the smallest id for which
 the rw trx can possibly be active. (But, you must look at the trx->state
 to find out if the minimum trx id transaction itself is active, or already
 committed.)
 @return the minimum trx id, or trx_sys->max_trx_id if rw trx list is empty */
UNIV_INLINE
trx_id_t trx_rw_min_trx_id(void) {
  trx_sys_mutex_enter();

  trx_id_t id = trx_rw_min_trx_id_low();

  trx_sys_mutex_exit();

  return (id);
}

UNIV_INLINE
trx_t *trx_rw_is_active_low(trx_id_t trx_id, ibool *corrupt) {
  trx_t *trx;

  ut_ad(trx_sys_mutex_own());

  if (trx_id < trx_rw_min_trx_id_low()) {
    trx = NULL;
  } else if (trx_id >= trx_sys->max_trx_id) {
    /* There must be corruption: we let the caller handle the
    diagnostic prints in this case. */

    trx = NULL;
    if (corrupt != NULL) {
      *corrupt = TRUE;
    }
  } else {
    trx = trx_get_rw_trx_by_id(trx_id);
    /* We remove trx from rw trxs list and change state to
    TRX_STATE_COMMITTED_IN_MEMORY in a same critical section protected by
    trx_sys->mutex, which we happen to hold here, so we expect the state of trx
    to match its presence in that list */
    ut_ad(trx == NULL || !trx_state_eq(trx, TRX_STATE_COMMITTED_IN_MEMORY));
  }

  return (trx);
}

UNIV_INLINE
trx_t *trx_rw_is_active(trx_id_t trx_id, ibool *corrupt, bool do_ref_count) {
  trx_t *trx;

  /* Fast checking. If it's smaller than minimal active trx id, just
  return NULL. */

  if (lizard::lizard_sys_get_min_active_trx_id() > trx_id) {
    return (NULL);
  }

  trx_sys_mutex_enter();

  trx = trx_rw_is_active_low(trx_id, corrupt);

  if (trx != 0) {
    trx = trx_reference(trx, do_ref_count);
  }

  trx_sys_mutex_exit();

  return (trx);
}

/** Allocates a new transaction id.
 @return new, allocated trx id */
UNIV_INLINE
trx_id_t trx_sys_get_new_trx_id() {
  ut_ad(trx_sys_mutex_own());

  /* VERY important: after the database is started, max_trx_id value is
  divisible by TRX_SYS_TRX_ID_WRITE_MARGIN, and the following if
  will evaluate to TRUE when this function is first time called,
  and the value for trx id will be written to disk-based header!
  Thus trx id values will not overlap when the database is
  repeatedly started! */

  if (!(trx_sys->max_trx_id % TRX_SYS_TRX_ID_WRITE_MARGIN)) {
    trx_sys_flush_max_trx_id();
  }

  return (trx_sys->max_trx_id++);
}

inline trx_id_t trx_sys_get_max_trx_id() {
  ut_ad(!trx_sys_mutex_own());

  if (UNIV_WORD_SIZE < DATA_TRX_ID_LEN) {
    /* Avoid torn reads. */

    trx_sys_mutex_enter();

    trx_id_t max_trx_id = trx_sys->max_trx_id;

    trx_sys_mutex_exit();

    return (max_trx_id);
  } else {
    /* Perform a dirty read. Callers should be prepared for stale
    values, and we know that the value fits in a machine word, so
    that it will be read and written atomically. */

    return (trx_sys->max_trx_id);
  }
}

/** Determine if there are incomplete transactions in the system.
@return whether incomplete transactions need rollback */
UNIV_INLINE
bool trx_sys_need_rollback() {
  ulint n_trx;

  trx_sys_mutex_enter();

  n_trx = UT_LIST_GET_LEN(trx_sys->rw_trx_list);
  ut_ad(n_trx >= trx_sys->n_prepared_trx);
  n_trx -= trx_sys->n_prepared_trx;

  trx_sys_mutex_exit();

  return (n_trx > 0);
}

/**
Add the transaction to the RW transaction set
@param trx		transaction instance to add */
UNIV_INLINE
void trx_sys_rw_trx_add(trx_t *trx) {
  ut_ad(trx->id != 0);

  trx_sys->rw_trx_hash.insert(TrxPair(trx->id, trx));
  ut_d(trx->in_rw_trx_list = true);
}

#endif /* !UNIV_HOTBACKUP */