michael_list_nogc.h

// Copyright (c) 2006-2018 Maxim Khizhinsky
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef CDSLIB_CONTAINER_MICHAEL_LIST_NOGC_H
#define CDSLIB_CONTAINER_MICHAEL_LIST_NOGC_H

#include <memory>
#include <cds/container/details/michael_list_base.h>
#include <cds/intrusive/michael_list_nogc.h>
#include <cds/container/details/make_michael_list.h>

namespace cds { namespace container {

    //@cond
    namespace details {

        template <typename T, class Traits>
        struct make_michael_list_nogc: public make_michael_list<gc::nogc, T, Traits>
        {
            typedef make_michael_list<cds::gc::nogc, T, Traits>  base_maker;
            typedef typename base_maker::node_type node_type;

            struct intrusive_traits: public base_maker::intrusive_traits
            {
                typedef typename base_maker::node_deallocator    disposer;
            };

            typedef intrusive::MichaelList<cds::gc::nogc, node_type, intrusive_traits>  type;
        };

    }   // namespace details
    //@endcond

    /// Michael's lock-free ordered single-linked list (template specialization for \p gc::nogc)
    /** @ingroup cds_nonintrusive_list
        \anchor cds_nonintrusive_MichaelList_nogc

        This specialization is intended for so-called append-only usage when no item
        reclamation may be performed. The class does not support deleting of list item.
        Usually, ordered single-linked list is used as a building block for the hash table implementation.
        The complexity of searching is <tt>O(N)</tt>.

        See \ref cds_nonintrusive_MichaelList_gc "MichaelList" for description of template parameters.
    */
    template <typename T,
#ifdef CDS_DOXYGEN_INVOKED
        class Traits = michael_list::traits
#else
        class Traits
#endif
    >
    class MichaelList<gc::nogc, T, Traits>:
#ifdef CDS_DOXYGEN_INVOKED
        protected intrusive::MichaelList< gc::nogc, T, Traits >
#else
        protected details::make_michael_list_nogc< T, Traits >::type
#endif
    {
        //@cond
        typedef details::make_michael_list_nogc< T, Traits > maker;
        typedef typename maker::type  base_class;
        //@endcond

    public:
        typedef cds::gc::nogc gc;         ///< Garbage collector used
        typedef T             value_type; ///< Type of value stored in the list
        typedef Traits        traits;     ///< List traits

        typedef typename base_class::back_off     back_off;       ///< Back-off strategy used
        typedef typename maker::allocator_type    allocator_type; ///< Allocator type used for allocate/deallocate the nodes
        typedef typename base_class::item_counter item_counter;   ///< Item counting policy used
        typedef typename maker::key_comparator    key_comparator; ///< key comparison functor
        typedef typename base_class::memory_model memory_model;   ///< Memory ordering. See cds::opt::memory_model option
        typedef typename base_class::stat         stat;           ///< Internal statistics

        //@cond
        // Rebind traits (split-list support)
        template <typename... Options>
        struct rebind_traits {
            typedef MichaelList<
                gc
                , value_type
                , typename cds::opt::make_options< traits, Options...>::type
            > type;
        };

        // Stat selector
        template <typename Stat>
        using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
        //@endcond

    protected:
        //@cond
        typedef typename base_class::value_type   node_type;
        typedef typename maker::cxx_allocator     cxx_allocator;
        typedef typename maker::node_deallocator  node_deallocator;
        typedef typename maker::intrusive_traits::compare  intrusive_key_comparator;

        typedef typename base_class::atomic_node_ptr head_type;

        struct node_disposer {
            void operator()( node_type * pNode )
            {
                free_node( pNode );
            }
        };

        typedef std::unique_ptr< node_type, node_disposer >     scoped_node_ptr;
        //@endcond

    protected:
        //@cond
        template <bool IsConst>
        class iterator_type: protected base_class::template iterator_type<IsConst>
        {
            typedef typename base_class::template iterator_type<IsConst>    iterator_base;

            iterator_type( head_type const& pNode )
                : iterator_base( pNode )
            {}

            explicit iterator_type( const iterator_base& it )
                : iterator_base( it )
            {}

            friend class MichaelList;

        protected:
            explicit iterator_type( node_type& pNode )
                : iterator_base( &pNode )
            {}

        public:
            typedef typename cds::details::make_const_type<value_type, IsConst>::pointer   value_ptr;
            typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;

            iterator_type()
            {}

            iterator_type( const iterator_type& src )
                : iterator_base( src )
            {}

            value_ptr operator ->() const
            {
                typename iterator_base::value_ptr p = iterator_base::operator ->();
                return p ? &(p->m_Value) : nullptr;
            }

            value_ref operator *() const
            {
                return (iterator_base::operator *()).m_Value;
            }

            /// Pre-increment
            iterator_type& operator ++()
            {
                iterator_base::operator ++();
                return *this;
            }

            /// Post-increment
            iterator_type operator ++(int)
            {
                return iterator_base::operator ++(0);
            }

            template <bool C>
            bool operator ==(iterator_type<C> const& i ) const
            {
                return iterator_base::operator ==(i);
            }
            template <bool C>
            bool operator !=(iterator_type<C> const& i ) const
            {
                return iterator_base::operator !=(i);
            }
        };
        //@endcond

    public:
   ///@name Forward iterators
   //@{
        /// Returns a forward iterator addressing the first element in a list
        /**
            For empty list \code begin() == end() \endcode
        */
        typedef iterator_type<false>    iterator;

        /// Const forward iterator
        /**
            For iterator's features and requirements see \ref iterator
        */
        typedef iterator_type<true>     const_iterator;

        /// Returns a forward iterator addressing the first element in a list
        /**
            For empty list \code begin() == end() \endcode
        */
        iterator begin()
        {
            return iterator( head());
        }

        /// Returns an iterator that addresses the location succeeding the last element in a list
        /**
            Do not use the value returned by <tt>end</tt> function to access any item.
            Internally, <tt>end</tt> returning value equals to \p nullptr.

            The returned value can be used only to control reaching the end of the list.
            For empty list \code begin() == end() \endcode
        */
        iterator end()
        {
            return iterator();
        }

        /// Returns a forward const iterator addressing the first element in a list
        const_iterator begin() const
        {
            return const_iterator( head());
        }

        /// Returns a forward const iterator addressing the first element in a list
        const_iterator cbegin() const
        {
            return const_iterator( head());
        }

        /// Returns an const iterator that addresses the location succeeding the last element in a list
        const_iterator end() const
        {
            return const_iterator();
        }

        /// Returns an const iterator that addresses the location succeeding the last element in a list
        const_iterator cend() const
        {
            return const_iterator();
        }
    //@}

    public:
        /// Default constructor
        /**
            Initialize empty list
        */
        MichaelList()
        {}

        //@cond
        template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
        explicit MichaelList( Stat& st )
            : base_class( st )
        {}
        //@endcond

        /// List destructor
        /**
            Clears the list
        */
        ~MichaelList()
        {
            clear();
        }

        /// Inserts new node
        /**
            The function inserts \p val in the list if the list does not contain
            an item with key equal to \p val.

            Return an iterator pointing to inserted item if success \ref end() otherwise
        */
        template <typename Q>
        iterator insert( Q&& val )
        {
            return node_to_iterator( insert_at( head(), std::forward<Q>( val )));
        }

        /// Updates the item
        /**
            If \p key is not in the list and \p bAllowInsert is \p true,
            the function inserts a new item.
            Otherwise, the function returns an iterator pointing to the item found.

            Returns <tt> std::pair<iterator, bool>  </tt> where \p first is an iterator pointing to
            item found or inserted, \p second is true if new item has been added or \p false if the item
            already is in the list.
        */
        template <typename Q>
        std::pair<iterator, bool> update( Q&& key, bool bAllowInsert = true )
        {
            std::pair< node_type *, bool > ret = update_at( head(), std::forward<Q>( key ), bAllowInsert );
            return std::make_pair( node_to_iterator( ret.first ), ret.second );
        }
        //@cond
        template <typename Q>
        CDS_DEPRECATED("ensure() is deprecated, use update()")
        std::pair<iterator, bool> ensure( const Q& val )
        {
            return update( val, true );
        }
        //@endcond

        /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
        /**
            Return an iterator pointing to inserted item if success \ref end() otherwise
        */
        template <typename... Args>
        iterator emplace( Args&&... args )
        {
            return node_to_iterator( emplace_at( head(), std::forward<Args>(args)... ));
        }

        /// Checks whether the list contains \p key
        /**
            The function searches the item with key equal to \p key
            and returns an iterator pointed to item found if the key is found,
            and \ref end() otherwise
        */
        template <typename Q>
        iterator contains( Q const& key )
        {
            return node_to_iterator( find_at( head(), key, intrusive_key_comparator()));
        }
        //@cond
        template <typename Q>
        CDS_DEPRECATED("deprecated, use contains()")
        iterator find( Q const& key )
        {
            return contains( key );
        }
        //@endcond

        /// Checks whether the map contains \p key using \p pred predicate for searching
        /**
            The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
            \p Less functor has the interface like \p std::less.
            \p Less must imply the same element order as the comparator used for building the list.
        */
        template <typename Q, typename Less>
        iterator contains( Q const& key, Less pred )
        {
            CDS_UNUSED( pred );
            return node_to_iterator( find_at( head(), key, typename maker::template less_wrapper<Less>()));
        }
        //@cond
        template <typename Q, typename Less>
        CDS_DEPRECATED("deprecated, use contains()")
        iterator find_with( Q const& key, Less pred )
        {
            return contains( key, pred );
        }
        //@endcond

        /// Check if the list is empty
        bool empty() const
        {
            return base_class::empty();
        }

        /// Returns list's item count
        /**
            The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
            this function always returns 0.

            @note Even if you use real item counter and it returns 0, this fact does not mean that the list
            is empty. To check list emptyness use \p empty() method.
        */
        size_t size() const
        {
            return base_class::size();
        }

        /// Returns const reference to internal statistics
        stat const& statistics() const
        {
            return base_class::statistics();
        }

        /// Clears the list
        void clear()
        {
            base_class::clear();
        }

    protected:
        //@cond
        static value_type& node_to_value( node_type& n )
        {
            return n.m_Value;
        }

        static node_type * alloc_node()
        {
            return cxx_allocator().New();
        }

        static node_type * alloc_node( value_type const& v )
        {
            return cxx_allocator().New( v );
        }

        template <typename... Args>
        static node_type * alloc_node( Args&&... args )
        {
            return cxx_allocator().MoveNew( std::forward<Args>( args )... );
        }

        static void free_node( node_type * pNode )
        {
            cxx_allocator().Delete( pNode );
        }

        head_type& head()
        {
            return base_class::m_pHead;
        }

        head_type const& head() const
        {
            return base_class::m_pHead;
        }

        iterator node_to_iterator( node_type * pNode )
        {
            if ( pNode )
                return iterator( *pNode );
            return end();
        }

        iterator insert_node( node_type * pNode )
        {
            return node_to_iterator( insert_node_at( head(), pNode ));
        }

        node_type * insert_node_at( head_type& refHead, node_type * pNode )
        {
            assert( pNode != nullptr );
            scoped_node_ptr p(pNode);
            if ( base_class::insert_at( refHead, *pNode ))
                return p.release();

            return nullptr;
        }

        template <typename Q>
        node_type * insert_at( head_type& refHead, Q&& val )
        {
            return insert_node_at( refHead, alloc_node( std::forward<Q>( val )));
        }

        template <typename Q>
        std::pair< node_type *, bool > update_at( head_type& refHead, Q&& val, bool bAllowInsert )
        {
            scoped_node_ptr pNode( alloc_node( std::forward<Q>( val )));
            node_type * pItemFound = nullptr;

            std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
                [&pItemFound](bool, node_type& item, node_type&) { pItemFound = &item; },
                bAllowInsert );

            if ( ret.second )
                pNode.release();
            return std::make_pair( pItemFound, ret.second );
        }

        template <typename... Args>
        node_type * emplace_at( head_type& refHead, Args&&... args )
        {
            return insert_node_at( refHead, alloc_node( std::forward<Args>(args)...));
        }

        template <typename Q, typename Compare>
        node_type * find_at( head_type& refHead, Q const& key, Compare cmp )
        {
            return base_class::find_at( refHead, key, cmp );
        }
        //@endcond
    };
}} // namespace cds::container

#endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_NOGC_H