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

Copyright (c) 2007, 2018, Oracle and/or its affiliates. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License, version 2.0, as published by the
Free Software Foundation.

This program is also distributed with certain software (including but not
limited to OpenSSL) that is licensed under separate terms, as designated in a
particular file or component or in included license documentation. The authors
of MySQL hereby grant you an additional permission to link the program and
your derivative works with the separately licensed software that they have
included with MySQL.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

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

/** @file include/lock0iter.h
 Lock queue iterator type and function prototypes.

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

#ifndef lock0iter_h
#define lock0iter_h

#include "lock0types.h"
#include "univ.i"

struct lock_queue_iterator_t {
  const lock_t *current_lock;
  /* In case this is a record lock queue (not table lock queue)
  then bit_no is the record number within the heap in which the
  record is stored. */
  ulint bit_no;
};

/** Initialize lock queue iterator so that it starts to iterate from
 "lock". bit_no specifies the record number within the heap where the
 record is stored. It can be undefined (ULINT_UNDEFINED) in two cases:
 1. If the lock is a table lock, thus we have a table lock queue;
 2. If the lock is a record lock and it is a wait lock. In this case
    bit_no is calculated in this function by using
    lock_rec_find_set_bit(). There is exactly one bit set in the bitmap
    of a wait lock. */
void lock_queue_iterator_reset(
    lock_queue_iterator_t *iter, /*!< out: iterator */
    const lock_t *lock,          /*!< in: lock to start from */
    ulint bit_no);               /*!< in: record number in the
                                 heap */

/** Gets the previous lock in the lock queue, returns NULL if there are no
 more locks (i.e. the current lock is the first one). The iterator is
 receded (if not-NULL is returned).
 @return previous lock or NULL */
const lock_t *lock_queue_iterator_get_prev(
    lock_queue_iterator_t *iter); /*!< in/out: iterator */

#endif /* lock0iter_h */