polardbxengine/storage/innobase/include/lock0priv.ic

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/** @file include/lock0priv.ic
 Lock module internal inline methods.

 Created July 16, 2007 Vasil Dimov
 *******************************************************/

/* This file contains only methods which are used in
lock/lock0* files, other than lock/lock0lock.cc.
I.e. lock/lock0lock.cc contains more internal inline
methods but they are used only in that file. */

#ifndef LOCK_MODULE_IMPLEMENTATION
#error Do not include lock0priv.ic outside of the lock/ module
#endif

/** Gets the type of a lock.
 @return LOCK_TABLE or LOCK_REC */
UNIV_INLINE
uint32_t lock_get_type_low(const lock_t *lock) /*!< in: lock */
{
  ut_ad(lock);

  return (lock->type_mode & LOCK_TYPE_MASK);
}

/** Checks if some transaction has an implicit x-lock on a record in a clustered
 index.
 @return transaction id of the transaction which has the x-lock, or 0 */
UNIV_INLINE
trx_id_t lock_clust_rec_some_has_impl(
    const rec_t *rec,          /*!< in: user record */
    const dict_index_t *index, /*!< in: clustered index */
    const ulint *offsets)      /*!< in: rec_get_offsets(rec, index) */
{
  ut_ad(index->is_clustered());
  ut_ad(page_rec_is_user_rec(rec));

  return (row_get_rec_trx_id(rec, index, offsets));
}

/** Gets the number of bits in a record lock bitmap.
 @return	number of bits */
UNIV_INLINE
ulint lock_rec_get_n_bits(const lock_t *lock) /*!< in: record lock */
{
  return (lock->rec_lock.n_bits);
}

/** Sets the nth bit of a record lock to TRUE. */
UNIV_INLINE
void lock_rec_set_nth_bit(lock_t *lock, /*!< in: record lock */
                          ulint i)      /*!< in: index of the bit */
{
  ulint byte_index;
  ulint bit_index;

  ut_ad(lock);
  ut_ad(lock_get_type_low(lock) == LOCK_REC);
  ut_ad(i < lock->rec_lock.n_bits);

  byte_index = i / 8;
  bit_index = i % 8;

  ((byte *)&lock[1])[byte_index] |= 1 << bit_index;

  lock->trx->lock.n_rec_locks.fetch_add(1, std::memory_order_relaxed);
}

/** Gets the first or next record lock on a page.
 @return	next lock, NULL if none exists */
UNIV_INLINE
lock_t *lock_rec_get_next_on_page(lock_t *lock) /*!< in: a record lock */
{
  return ((lock_t *)lock_rec_get_next_on_page_const(lock));
}

/** Gets the first record lock on a page, where the page is identified by its
 file address.
 @return	first lock, NULL if none exists */
UNIV_INLINE
lock_t *lock_rec_get_first_on_page_addr(
    hash_table_t *lock_hash, /*!< in: Lock hash table */
    space_id_t space,        /*!< in: space */
    page_no_t page_no)       /*!< in: page number */
{
  ut_ad(lock_mutex_own());

  for (lock_t *lock = static_cast<lock_t *>(
           HASH_GET_FIRST(lock_hash, lock_rec_hash(space, page_no)));
       lock != NULL; lock = static_cast<lock_t *>(HASH_GET_NEXT(hash, lock))) {
    if (lock->space_id() == space && lock->page_no() == page_no) {
      return (lock);
    }
  }

  return (NULL);
}

/** Gets the first record lock on a page, where the page is identified by a
 pointer to it.
 @return	first lock, NULL if none exists */
UNIV_INLINE
lock_t *lock_rec_get_first_on_page(
    hash_table_t *lock_hash,  /*!< in: lock hash table */
    const buf_block_t *block) /*!< in: buffer block */
{
  ut_ad(lock_mutex_own());

  space_id_t space = block->page.id.space();
  page_no_t page_no = block->page.id.page_no();
  ulint hash = buf_block_get_lock_hash_val(block);

  for (lock_t *lock = static_cast<lock_t *>(HASH_GET_FIRST(lock_hash, hash));
       lock != NULL; lock = static_cast<lock_t *>(HASH_GET_NEXT(hash, lock))) {
    if (lock->space_id() == space && lock->page_no() == page_no) {
      return (lock);
    }
  }

  return (NULL);
}

/** Gets the next explicit lock request on a record.
 @return	next lock, NULL if none exists or if heap_no == ULINT_UNDEFINED
 */
UNIV_INLINE
lock_t *lock_rec_get_next(ulint heap_no, /*!< in: heap number of the record */
                          lock_t *lock)  /*!< in: lock */
{
  ut_ad(lock_mutex_own());

  do {
    ut_ad(lock_get_type_low(lock) == LOCK_REC);
    lock = lock_rec_get_next_on_page(lock);
  } while (lock != nullptr && !lock_rec_get_nth_bit(lock, heap_no));

  return (lock);
}

/** Gets the next explicit lock request on a record.
 @return	next lock, NULL if none exists or if heap_no == ULINT_UNDEFINED
 */
UNIV_INLINE
const lock_t *lock_rec_get_next_const(
    ulint heap_no,      /*!< in: heap number of the record */
    const lock_t *lock) /*!< in: lock */
{
  return (lock_rec_get_next(heap_no, (lock_t *)lock));
}

/** Gets the first explicit lock request on a record.
@param[in]	hash		Record hash
@param[in]	rec_id		Record ID
@return	first lock, nullptr if none exists */
UNIV_INLINE
lock_t *lock_rec_get_first(hash_table_t *hash, const RecID &rec_id) {
  ut_ad(lock_mutex_own());

  auto lock = lock_rec_get_first_on_page_addr(hash, rec_id.m_space_id,
                                              rec_id.m_page_no);

  if (lock != nullptr && !lock_rec_get_nth_bit(lock, rec_id.m_heap_no)) {
    lock = lock_rec_get_next(rec_id.m_heap_no, lock);
  }

  return (lock);
}

/** Gets the first explicit lock request on a record.
 @return	first lock, NULL if none exists */
UNIV_INLINE
lock_t *lock_rec_get_first(
    hash_table_t *hash,       /*!< in: hash chain the lock on */
    const buf_block_t *block, /*!< in: block containing the record */
    ulint heap_no)            /*!< in: heap number of the record */
{
  ut_ad(lock_mutex_own());

  for (lock_t *lock = lock_rec_get_first_on_page(hash, block); lock;
       lock = lock_rec_get_next_on_page(lock)) {
    if (lock_rec_get_nth_bit(lock, heap_no)) {
      return (lock);
    }
  }

  return (NULL);
}

/** Gets the nth bit of a record lock.
@param[in]	lock		Record lock
@param[in]	i		Index of the bit to check
@return true if bit set also if i == ULINT_UNDEFINED return false */
UNIV_INLINE
bool lock_rec_get_nth_bit(const lock_t *lock, ulint i) {
  const byte *b;

  ut_ad(lock);
  ut_ad(lock_get_type_low(lock) == LOCK_REC);

  if (i >= lock->rec_lock.n_bits) {
    return (false);
  }

  b = ((const byte *)&lock[1]) + (i / 8);

  return (true & *b >> (i % 8));
}

/** Gets the first or next record lock on a page.
 @return next lock, NULL if none exists */
UNIV_INLINE
const lock_t *lock_rec_get_next_on_page_const(
    const lock_t *lock) /*!< in: a record lock */
{
  ut_ad(lock_mutex_own());
  ut_ad(lock_get_type_low(lock) == LOCK_REC);

  space_id_t space = lock->space_id();
  page_no_t page_no = lock->page_no();

  while ((lock = static_cast<const lock_t *>(HASH_GET_NEXT(hash, lock))) !=
         NULL) {
    if (lock->space_id() == space && lock->page_no() == page_no) {
      return (lock);
    }
  }

  return (NULL);
}

/** Gets the mode of a lock.
 @return mode */
UNIV_INLINE
enum lock_mode lock_get_mode(const lock_t *lock) /*!< in: lock */
{
  ut_ad(lock);

  return (static_cast<enum lock_mode>(lock->type_mode & LOCK_MODE_MASK));
}

/** Calculates if lock mode 1 is compatible with lock mode 2.
 @return nonzero if mode1 compatible with mode2 */
UNIV_INLINE
ulint lock_mode_compatible(enum lock_mode mode1, /*!< in: lock mode */
                           enum lock_mode mode2) /*!< in: lock mode */
{
  ut_ad((ulint)mode1 < lock_types);
  ut_ad((ulint)mode2 < lock_types);

  return (lock_compatibility_matrix[mode1][mode2]);
}

UNIV_INLINE
bool lock_mode_stronger_or_eq(enum lock_mode mode1, enum lock_mode mode2) {
  ut_ad((ulint)mode1 < lock_types);
  ut_ad((ulint)mode2 < lock_types);

  return (lock_strength_matrix[mode1][mode2] != 0);
}

/** Gets the wait flag of a lock.
 @return LOCK_WAIT if waiting, 0 if not */
UNIV_INLINE
ulint lock_get_wait(const lock_t *lock) /*!< in: lock */
{
  ut_ad(lock);

  return (lock->type_mode & LOCK_WAIT);
}

/** The back pointer to a waiting lock request in the transaction is set to NULL
 and the wait bit in lock type_mode is reset. */
UNIV_INLINE
void lock_reset_lock_and_trx_wait(lock_t *lock) /*!< in/out: record lock */
{
  ut_ad(lock->trx->lock.wait_lock == lock);
  ut_ad(lock_get_wait(lock));
  ut_ad(lock_mutex_own());

  /* We intentionally don't clear trx->lock.blocking_trx here, as
  lock_reset_lock_and_trx_wait() is called also during movements of locks from
  one page to another, which does not really change the structure of the
  wait-for graph. Instead the lock_reset_wait_and_release_thread_if_suspended()
  is responsible for clearing the blocking_trx field once it is sure that
  we really want to remove the edge from the wait-for graph.*/
  lock->trx->lock.wait_lock = NULL;
  /* We intentionally don't clear lock->trx->lock.wait_lock_type here, to make
  it easier to obtain stats about the last wait in lock_wait_suspend_thread().
  @see trx_lock_t::wait_lock_type for more detailed explanation. */
  lock->type_mode &= ~LOCK_WAIT;
}

/** Looks for a suitable type record lock struct by the same trx on the same
 page. This can be used to save space when a new record lock should be set on a
 page: no new struct is needed, if a suitable old is found.
 @return lock or NULL */
UNIV_INLINE
lock_t *lock_rec_find_similar_on_page(
    ulint type_mode,  /*!< in: lock type_mode field */
    ulint heap_no,    /*!< in: heap number of the record */
    lock_t *lock,     /*!< in: lock_rec_get_first_on_page() */
    const trx_t *trx) /*!< in: transaction */
{
  ut_ad(lock_mutex_own());

  for (/* No op */; lock != NULL; lock = lock_rec_get_next_on_page(lock)) {
    if (lock->trx == trx && lock->type_mode == type_mode &&
        lock_rec_get_n_bits(lock) > heap_no) {
      return (lock);
    }
  }

  return (NULL);
}

UNIV_INLINE
bool lock_table_has(const trx_t *trx, const dict_table_t *table,
                    lock_mode in_mode) {
  ut_ad(!trx_mutex_own(trx));
  trx_mutex_enter(trx);

  if (trx->lock.table_locks.empty()) {
    trx_mutex_exit(trx);
    return (false);
  }

  typedef lock_pool_t::const_reverse_iterator iterator;

  iterator end = trx->lock.table_locks.rend();

  /* Look for stronger locks the same trx already has on the table */

  for (iterator it = trx->lock.table_locks.rbegin(); it != end; ++it) {
    const lock_t *lock = *it;

    ut_ad(lock != nullptr);

    lock_mode mode = lock_get_mode(lock);

    ut_ad(trx == lock->trx);
    ut_ad(lock_get_type_low(lock) & LOCK_TABLE);
    ut_ad(lock->tab_lock.table != NULL);

    if (table == lock->tab_lock.table &&
        lock_mode_stronger_or_eq(mode, in_mode)) {
      ut_ad(!lock_get_wait(lock));

      trx_mutex_exit(trx);
      return (true);
    }
  }

  trx_mutex_exit(trx);
  return (false);
}

/* Check if the rec id matches the lock instance.
@param[i]	lock		Lock to compare with
@return true if <space, page_no, heap_no> matches the lock. */
bool RecID::matches(const lock_t *lock) const {
  return (lock->rec_lock.space == m_space_id &&
          lock->rec_lock.page_no == m_page_no &&
          lock_rec_get_nth_bit(lock, m_heap_no));
}

/* vim: set filetype=c: */