polardbxengine/storage/innobase/include/ut0lst.h

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

Copyright (c) 1995, 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/ut0lst.h
 List utilities

 Created 9/10/1995 Heikki Tuuri
 Rewritten by Sunny Bains Dec 2011.
 ***********************************************************************/

#ifndef ut0lst_h
#define ut0lst_h

/* Do not include univ.i because univ.i includes this. */

#include "ut0dbg.h"

/* This module implements the two-way linear list. Note that a single
list node may belong to two or more lists, but is only on one list
at a time. */

/** The two way list node.
 @tparam Type the list node type name */
template <typename Type>
struct ut_list_node {
  Type *prev; /*!< pointer to the previous
              node, NULL if start of list */
  Type *next; /*!< pointer to next node,
              NULL if end of list */

  void reverse() {
    Type *tmp = prev;
    prev = next;
    next = tmp;
  }
};

/** Macro used for legacy reasons */
#define UT_LIST_NODE_T(t) ut_list_node<t>

/** The two-way list base node. The base node contains pointers to both ends
 of the list and a count of nodes in the list (excluding the base node
 from the count). We also store a pointer to the member field so that it
 doesn't have to be specified when doing list operations.
 @tparam Type the type of the list element
 @tparam NodePtr field member pointer that points to the list node */
template <typename Type, typename NodePtr>
struct ut_list_base {
  typedef Type elem_type;
  typedef NodePtr node_ptr;
  typedef ut_list_node<Type> node_type;

  ulint count{0};            /*!< count of nodes in list */
  elem_type *start{nullptr}; /*!< pointer to list start,
                             NULL if empty */
  elem_type *end{nullptr};   /*!< pointer to list end,
                             NULL if empty */
  node_ptr node{nullptr};    /*!< Pointer to member field
                             that is used as a link node */
#ifdef UNIV_DEBUG
  ulint init{0}; /*!< UT_LIST_INITIALISED if
                 the list was initialised with
                 UT_LIST_INIT() */
#endif           /* UNIV_DEBUG */

  void reverse() {
    Type *tmp = start;
    start = end;
    end = tmp;
  }
};

#define UT_LIST_BASE_NODE_T(t) ut_list_base<t, ut_list_node<t> t::*>

#ifdef UNIV_DEBUG
#define UT_LIST_INITIALISED 0xCAFE
#define UT_LIST_INITIALISE(b) (b).init = UT_LIST_INITIALISED
#define UT_LIST_IS_INITIALISED(b) ut_a(((b).init == UT_LIST_INITIALISED))
#else
#define UT_LIST_INITIALISE(b)
#define UT_LIST_IS_INITIALISED(b)
#endif /* UNIV_DEBUG */

/** Note: This is really the list constructor. We should be able to use
 placement new here.
 Initializes the base node of a two-way list.
 @param b the list base node
 @param pmf point to member field that will be used as the link node */
#define UT_LIST_INIT(b, pmf) \
  {                          \
    (b).count = 0;           \
    (b).start = 0;           \
    (b).end = 0;             \
    (b).node = pmf;          \
    UT_LIST_INITIALISE(b);   \
  }

/** Functor for accessing the embedded node within a list element. This is
required because some lists can have the node emebedded inside a nested
struct/union. See lock0priv.h (table locks) for an example. It provides a
specialised functor to grant access to the list node. */
template <typename Type>
struct GenericGetNode {
  typedef ut_list_node<Type> node_type;

  GenericGetNode(node_type Type::*node) : m_node(node) {}

  node_type &operator()(Type &elem) { return (elem.*m_node); }

  node_type Type::*m_node;
};

/** Adds the node as the first element in a two-way linked list.
 @param list the base node (not a pointer to it)
 @param elem the element to add */
template <typename List>
void ut_list_prepend(List &list, typename List::elem_type *elem) {
  typename List::node_type &elem_node = elem->*list.node;

  UT_LIST_IS_INITIALISED(list);

  elem_node.prev = 0;
  elem_node.next = list.start;

  if (list.start != 0) {
    typename List::node_type &base_node = list.start->*list.node;

    ut_ad(list.start != elem);

    base_node.prev = elem;
  }

  list.start = elem;

  if (list.end == 0) {
    list.end = elem;
  }

  ++list.count;
}

/** Adds the node as the first element in a two-way linked list.
 @param LIST the base node (not a pointer to it)
 @param ELEM the element to add */
#define UT_LIST_ADD_FIRST(LIST, ELEM) ut_list_prepend(LIST, ELEM)

/** Adds the node as the last element in a two-way linked list.
 @param list list
 @param elem the element to add
 @param get_node to get the list node for that element */
template <typename List, typename Functor>
void ut_list_append(List &list, typename List::elem_type *elem,
                    Functor get_node) {
  typename List::node_type &node = get_node(*elem);

  UT_LIST_IS_INITIALISED(list);

  node.next = 0;
  node.prev = list.end;

  if (list.end != 0) {
    typename List::node_type &base_node = get_node(*list.end);

    ut_ad(list.end != elem);

    base_node.next = elem;
  }

  list.end = elem;

  if (list.start == 0) {
    list.start = elem;
  }

  ++list.count;
}

/** Adds the node as the last element in a two-way linked list.
 @param list list
 @param elem the element to add */
template <typename List>
void ut_list_append(List &list, typename List::elem_type *elem) {
  ut_list_append(list, elem,
                 GenericGetNode<typename List::elem_type>(list.node));
}

/** Adds the node as the last element in a two-way linked list.
 @param LIST list base node (not a pointer to it)
 @param ELEM the element to add */
#define UT_LIST_ADD_LAST(LIST, ELEM) ut_list_append(LIST, ELEM)

/** Inserts a ELEM2 after ELEM1 in a list.
 @param list the base node
 @param elem1 node after which ELEM2 is inserted
 @param elem2 node being inserted after ELEM1 */
template <typename List>
void ut_list_insert(List &list, typename List::elem_type *elem1,
                    typename List::elem_type *elem2) {
  ut_ad(elem1 != elem2);
  UT_LIST_IS_INITIALISED(list);

  typename List::node_type &elem1_node = elem1->*list.node;
  typename List::node_type &elem2_node = elem2->*list.node;

  elem2_node.prev = elem1;
  elem2_node.next = elem1_node.next;

  if (elem1_node.next != NULL) {
    typename List::node_type &next_node = elem1_node.next->*list.node;

    next_node.prev = elem2;
  }

  elem1_node.next = elem2;

  if (list.end == elem1) {
    list.end = elem2;
  }

  ++list.count;
}

/** Inserts a ELEM2 after ELEM1 in a list.
 @param LIST list base node (not a pointer to it)
 @param ELEM1 node after which ELEM2 is inserted
 @param ELEM2 node being inserted after ELEM1 */
#define UT_LIST_INSERT_AFTER(LIST, ELEM1, ELEM2) \
  ut_list_insert(LIST, ELEM1, ELEM2)

/** Removes a node from a two-way linked list.
 @param list the base node (not a pointer to it)
 @param node member node within list element that is to be removed
 @param get_node functor to get the list node from elem */
template <typename List, typename Functor>
void ut_list_remove(List &list, typename List::node_type &node,
                    Functor get_node) {
  ut_a(list.count > 0);
  UT_LIST_IS_INITIALISED(list);

  if (node.next != NULL) {
    typename List::node_type &next_node = get_node(*node.next);

    next_node.prev = node.prev;
  } else {
    list.end = node.prev;
  }

  if (node.prev != NULL) {
    typename List::node_type &prev_node = get_node(*node.prev);

    prev_node.next = node.next;
  } else {
    list.start = node.next;
  }

  node.next = 0;
  node.prev = 0;

  --list.count;
}

/** Removes a node from a two-way linked list.
 @param list the base node (not a pointer to it)
 @param elem element to be removed from the list
 @param get_node functor to get the list node from elem */
template <typename List, typename Functor>
void ut_list_remove(List &list, typename List::elem_type *elem,
                    Functor get_node) {
  ut_list_remove(list, get_node(*elem), get_node);
}

/** Removes a node from a two-way linked list.
 @param list the base node (not a pointer to it)
 @param elem element to be removed from the list */
template <typename List>
void ut_list_remove(List &list, typename List::elem_type *elem) {
  ut_list_remove(list, elem->*list.node,
                 GenericGetNode<typename List::elem_type>(list.node));
}

/** Removes a node from a two-way linked list.
 @param LIST the base node (not a pointer to it)
 @param ELEM node to be removed from the list */
#define UT_LIST_REMOVE(LIST, ELEM) ut_list_remove(LIST, ELEM)

/** Gets the next node in a two-way list.
 @param NAME list name
 @param N pointer to a node
 @return the successor of N in NAME, or NULL */
#define UT_LIST_GET_NEXT(NAME, N) (((N)->NAME).next)

/** Gets the previous node in a two-way list.
 @param NAME list name
 @param N pointer to a node
 @return the predecessor of N in NAME, or NULL */
#define UT_LIST_GET_PREV(NAME, N) (((N)->NAME).prev)

/** Alternative macro to get the number of nodes in a two-way list, i.e.,
 its length.
 @param BASE the base node (not a pointer to it).
 @return the number of nodes in the list */
#define UT_LIST_GET_LEN(BASE) (BASE).count

/** Gets the first node in a two-way list.
 @param BASE the base node (not a pointer to it)
 @return first node, or NULL if the list is empty */
#define UT_LIST_GET_FIRST(BASE) (BASE).start

/** Gets the last node in a two-way list.
 @param BASE the base node (not a pointer to it)
 @return last node, or NULL if the list is empty */
#define UT_LIST_GET_LAST(BASE) (BASE).end

struct NullValidate {
  void operator()(const void *elem) {}
};

/** Iterate over all the elements and call the functor for each element.
 @param[in]	list	base node (not a pointer to it)
 @param[in,out]	functor	Functor that is called for each element in the list */
template <typename List, class Functor>
void ut_list_map(const List &list, Functor &functor) {
  ulint count = 0;

  UT_LIST_IS_INITIALISED(list);

  for (typename List::elem_type *elem = list.start; elem != 0;
       elem = (elem->*list.node).next, ++count) {
    functor(elem);
  }

  ut_a(count == list.count);
}

template <typename List>
void ut_list_reverse(List &list) {
  UT_LIST_IS_INITIALISED(list);

  for (typename List::elem_type *elem = list.start; elem != 0;
       elem = (elem->*list.node).prev) {
    (elem->*list.node).reverse();
  }

  list.reverse();
}

#define UT_LIST_REVERSE(LIST) ut_list_reverse(LIST)

/** Checks the consistency of a two-way list.
 @param[in]		list base node (not a pointer to it)
 @param[in,out]		functor Functor that is called for each element in
 the list */
template <typename List, class Functor>
void ut_list_validate(const List &list, Functor &functor) {
  ut_list_map(list, functor);

  /* Validate the list backwards. */
  ulint count = 0;

  for (typename List::elem_type *elem = list.end; elem != 0;
       elem = (elem->*list.node).prev) {
    ++count;
  }

  ut_a(count == list.count);
}

/** Check the consistency of a two-way list.
@param[in] LIST base node reference */
#define UT_LIST_CHECK(LIST)        \
  do {                             \
    NullValidate nullV;            \
    ut_list_validate(LIST, nullV); \
  } while (0)

/** Move the given element to the beginning of the list.
@param[in,out]	list	the list object
@param[in]	elem	the element of the list which will be moved
                        to the beginning of the list. */
template <typename List>
void ut_list_move_to_front(List &list, typename List::elem_type *elem) {
  ut_ad(ut_list_exists(list, elem));

  if (UT_LIST_GET_FIRST(list) != elem) {
    ut_list_remove(list, elem);
    ut_list_prepend(list, elem);
  }
}

#ifdef UNIV_DEBUG
/** Check if the given element exists in the list.
@param[in,out]	list	the list object
@param[in]	elem	the element of the list which will be checked */
template <typename List>
bool ut_list_exists(List &list, typename List::elem_type *elem) {
  typename List::elem_type *e1;

  for (e1 = UT_LIST_GET_FIRST(list); e1 != NULL; e1 = (e1->*list.node).next) {
    if (elem == e1) {
      return (true);
    }
  }
  return (false);
}
#endif

#define UT_LIST_MOVE_TO_FRONT(LIST, ELEM) ut_list_move_to_front(LIST, ELEM)

#endif /* ut0lst.h */