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/** @file include/trx0trx.ic
 The transaction

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

#include "read0read.h"

/** Determines if a transaction is in the given state.
 The caller must hold trx_sys->mutex, or it must be the thread
 that is serving a running transaction.
 A running RW transaction must be in trx_sys->rw_trx_list.
 @return true if trx->state == state */
UNIV_INLINE
bool trx_state_eq(const trx_t *trx,  /*!< in: transaction */
                  trx_state_t state) /*!< in: state */
{
#ifdef UNIV_DEBUG
  switch (trx->state) {
    case TRX_STATE_PREPARED:

      ut_ad(!trx_is_autocommit_non_locking(trx));
      return (trx->state == state);

    case TRX_STATE_ACTIVE:

      assert_trx_nonlocking_or_in_list(trx);
      return (state == trx->state);

    case TRX_STATE_COMMITTED_IN_MEMORY:

      check_trx_state(trx);
      return (state == trx->state);

    case TRX_STATE_NOT_STARTED:
    case TRX_STATE_FORCED_ROLLBACK:

      /* These states are not allowed for running transactions. */
      ut_a(state == TRX_STATE_NOT_STARTED ||
           state == TRX_STATE_FORCED_ROLLBACK);

      ut_ad(!trx->in_rw_trx_list);

      return (true);
  }
  ut_error;
#else  /* UNIV_DEBUG */
  return (trx->state == state);
#endif /* UNIV_DEBUG */
}

/** Retrieves the index causing error from a trx.
@param[in]	trx	trx object
@return the error index */
UNIV_INLINE
const dict_index_t *trx_get_error_index(const trx_t *trx) {
  return (trx->error_index);
}

/** Retrieves transaction's que state in a human readable string. The string
 should not be free()'d or modified.
 @return string in the data segment */
UNIV_INLINE
const char *trx_get_que_state_str(const trx_t *trx) /*!< in: transaction */
{
  /* be sure to adjust TRX_QUE_STATE_STR_MAX_LEN if you change this */
  switch (trx->lock.que_state) {
    case TRX_QUE_RUNNING:
      return ("RUNNING");
    case TRX_QUE_LOCK_WAIT:
      return ("LOCK WAIT");
    case TRX_QUE_ROLLING_BACK:
      return ("ROLLING BACK");
    case TRX_QUE_COMMITTING:
      return ("COMMITTING");
    default:
      return ("UNKNOWN");
  }
}

/** Retreieves the transaction ID.
In a given point in time it is guaranteed that IDs of the running
transactions are unique. The values returned by this function for readonly
transactions may be reused, so a subsequent RO transaction may get the same ID
as a RO transaction that existed in the past. The values returned by this
function should be used for printing purposes only.
@param[in]	trx	transaction whose id to retrieve
@return transaction id */
UNIV_INLINE
trx_id_t trx_get_id_for_print(const trx_t *trx) {
  /* Readonly and transactions whose intentions are unknown (whether
  they will eventually do a WRITE) don't have trx_t::id assigned (it is
  0 for those transactions). Transaction IDs in
  information_schema.innodb_trx.trx_id,
  performance_schema.data_locks.engine_transaction_id,
  performance_schema.data_lock_waits.requesting_engine_transaction_id,
  performance_schema.data_lock_waits.blocking_engine_transaction_id
  should match because those tables
  could be used in an SQL JOIN on those columns. Also trx_t::id is
  printed by SHOW ENGINE INNODB STATUS, and in logs, so we must have the
  same value printed everywhere consistently. */

  /* DATA_TRX_ID_LEN is the storage size in bytes. */
  static const trx_id_t max_trx_id = (1ULL << (DATA_TRX_ID_LEN * CHAR_BIT)) - 1;

  ut_ad(trx->id <= max_trx_id);

  return (trx->id != 0 ? trx->id
                       : reinterpret_cast<trx_id_t>(trx) | (max_trx_id + 1));
}

/** Determine if a transaction is a dictionary operation.
 @return dictionary operation mode */
UNIV_INLINE
enum trx_dict_op_t trx_get_dict_operation(
    const trx_t *trx) /*!< in: transaction */
{
  trx_dict_op_t op = static_cast<trx_dict_op_t>(trx->dict_operation);

#ifdef UNIV_DEBUG
  switch (op) {
    case TRX_DICT_OP_NONE:
    case TRX_DICT_OP_TABLE:
    case TRX_DICT_OP_INDEX:
      return (op);
  }
  ut_error;
#endif /* UNIV_DEBUG */
  return (op);
}
/** Flag a transaction a dictionary operation. */
UNIV_INLINE
void trx_set_dict_operation(trx_t *trx,            /*!< in/out: transaction */
                            enum trx_dict_op_t op) /*!< in: operation, not
                                                   TRX_DICT_OP_NONE */
{
#ifdef UNIV_DEBUG
  enum trx_dict_op_t old_op = trx_get_dict_operation(trx);

  switch (op) {
    case TRX_DICT_OP_NONE:
      ut_error;
      break;
    case TRX_DICT_OP_TABLE:
      switch (old_op) {
        case TRX_DICT_OP_NONE:
        case TRX_DICT_OP_INDEX:
        case TRX_DICT_OP_TABLE:
          goto ok;
      }
      ut_error;
      break;
    case TRX_DICT_OP_INDEX:
      ut_ad(old_op == TRX_DICT_OP_NONE);
      break;
  }
ok:
#endif /* UNIV_DEBUG */

  trx->dict_operation = op;
}

/** Check if redo rseg is modified for insert/update. */
UNIV_INLINE
bool trx_is_redo_rseg_updated(const trx_t *trx) /*!< in: transaction */
{
  return (trx->rsegs.m_redo.insert_undo != 0 ||
          trx->rsegs.m_redo.update_undo != 0);
}

/** Check if noredo rseg is modified for insert/update. */
UNIV_INLINE
bool trx_is_temp_rseg_updated(const trx_t *trx) /*!< in: transaction */
{
  return (trx->rsegs.m_noredo.insert_undo != 0 ||
          trx->rsegs.m_noredo.update_undo != 0);
}

/** Check if redo/noredo rseg is modified for insert/update. */
UNIV_INLINE
bool trx_is_rseg_updated(const trx_t *trx) /*!< in: transaction */
{
  return (trx_is_redo_rseg_updated(trx) || trx_is_temp_rseg_updated(trx));
}

/** Check if redo/nonredo rseg is valid. */
UNIV_INLINE
bool trx_is_rseg_assigned(const trx_t *trx) /*!< in: transaction */
{
  return (trx->rsegs.m_redo.rseg != NULL || trx->rsegs.m_noredo.rseg != NULL);
}

/**
Increase the reference count. If the transaction is in state
TRX_STATE_COMMITTED_IN_MEMORY then the transaction is considered
committed and the reference count is not incremented.
@param trx Transaction that is being referenced
@param do_ref_count Increment the reference iff this is true
@return transaction instance if it is not committed */
UNIV_INLINE
trx_t *trx_reference(trx_t *trx, bool do_ref_count) {
  trx_mutex_enter(trx);

  if (trx_state_eq(trx, TRX_STATE_COMMITTED_IN_MEMORY)) {
    trx_mutex_exit(trx);
    trx = NULL;
  } else if (do_ref_count) {
    ut_ad(trx->n_ref >= 0);
    ++trx->n_ref;
    trx_mutex_exit(trx);
  } else {
    trx_mutex_exit(trx);
  }

  return (trx);
}

/**
Release the transaction. Decrease the reference count.
@param trx Transaction that is being released */
UNIV_INLINE
void trx_release_reference(trx_t *trx) {
  trx_mutex_enter(trx);

  ut_ad(trx->n_ref > 0);
  --trx->n_ref;

  trx_mutex_exit(trx);
}

/**
@param trx		Get the active vision for this transaction, if one exists
@return the transaction's vision or NULL if one not assigned. */
UNIV_INLINE
lizard::Vision *trx_get_vision(trx_t *trx) {
  /** read_view is being used or not assigned */
  return (&trx->vision);
}

/**
@param trx		Get the active view for this transaction, if one exists
@return the transaction's vsion or NULL if one not assigned. */
UNIV_INLINE
const lizard::Vision *trx_get_vision(const trx_t *trx) {
  /** read_view is being used or not assigned */
  return (&trx->vision);
}

///**
//@param trx		Get the active view for this transaction, if one exists
//@return the transaction's read view or NULL if one not assigned. */
//UNIV_INLINE
//ReadView *trx_get_read_view(trx_t *trx) {
//  return (!MVCC::is_view_active(trx->read_view) ? NULL : trx->read_view);
//}
//
///**
//@param trx		Get the active view for this transaction, if one exists
//@return the transaction's read view or NULL if one not assigned. */
//UNIV_INLINE
//const ReadView *trx_get_read_view(const trx_t *trx) {
//  return (!MVCC::is_view_active(trx->read_view) ? NULL : trx->read_view);
//}

/**
@param[in] trx		Transaction to check
@return true if the transaction is a high priority transaction.*/
UNIV_INLINE
bool trx_is_high_priority(const trx_t *trx) {
  if (trx->mysql_thd == NULL) {
    return (false);
  }

  return (thd_trx_priority(trx->mysql_thd) > 0);
}

/**
@param[in] requestor	Transaction requesting the lock
@param[in] holder	Transaction holding the lock
@return the transaction that will be rolled back, null don't care */
UNIV_INLINE
const trx_t *trx_arbitrate(const trx_t *requestor, const trx_t *holder) {
  ut_ad(!trx_is_autocommit_non_locking(holder));
  ut_ad(!trx_is_autocommit_non_locking(requestor));

  /* Note: Background stats collection transactions also acquire
  locks on user tables. They don't have an associated MySQL session
  instance. */

  if (requestor->mysql_thd == NULL) {
    ut_ad(!trx_is_high_priority(requestor));

    if (trx_is_high_priority(holder)) {
      return (requestor);
    } else {
      return (NULL);
    }

  } else if (holder->mysql_thd == NULL) {
    ut_ad(!trx_is_high_priority(holder));

    if (trx_is_high_priority(requestor)) {
      return (holder);
    }

    return (NULL);
  }

  const THD *victim =
      thd_trx_arbitrate(requestor->mysql_thd, holder->mysql_thd);

  ut_ad(victim == NULL || victim == requestor->mysql_thd ||
        victim == holder->mysql_thd);

  if (victim != NULL) {
    return (victim == requestor->mysql_thd ? requestor : holder);
  }

  return (NULL);
}