Remove unused vars

[libcds.git] / cds / container / impl / ellen_bintree_map.h

//$$CDS-header$$

#ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H
#define __CDS_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H

#include <type_traits>
#include <cds/container/details/ellen_bintree_base.h>
#include <cds/intrusive/impl/ellen_bintree.h>
#include <cds/container/details/guarded_ptr_cast.h>

namespace cds { namespace container {

    /// Map based on Ellen's et al binary search tree
    /** @ingroup cds_nonintrusive_map
        @ingroup cds_nonintrusive_tree
        @anchor cds_container_EllenBinTreeMap

        Source:
            - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"

        %EllenBinTreeMap is an unbalanced leaf-oriented binary search tree that implements the <i>map</i>
        abstract data type. Nodes maintains child pointers but not parent pointers.
        Every internal node has exactly two children, and all data of type <tt>std::pair<Key const, T></tt>
        currently in the tree are stored in the leaves. Internal nodes of the tree are used to direct \p find
        operation along the path to the correct leaf. The keys (of \p Key type) stored in internal nodes
        may or may not be in the map.
        Unlike \ref cds_container_EllenBinTreeSet "EllenBinTreeSet" keys are not a part of \p T type.
        The map can be represented as a set containing <tt>std::pair< Key const, T> </tt> values.

        Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeMap can act as
        a <i>priority queue</i>. In this case you should provide unique compound key, for example,
        the priority value plus some uniformly distributed random value.

        @warning Recall the tree is <b>unbalanced</b>. The complexity of operations is <tt>O(log N)</tt>
        for uniformly distributed random keys, but in worst case the complexity is <tt>O(N)</tt>.

        @note In the current implementation we do not use helping technique described in the original paper.
        In Hazard Pointer schema helping is too complicated and does not give any observable benefits.
        Instead of helping, when a thread encounters a concurrent operation it just spins waiting for
        the operation done. Such solution allows greatly simplify implementation of the tree.

        <b>Template arguments</b> :
        - \p GC - safe memory reclamation (i.e. light-weight garbage collector) type, like \p cds::gc::HP, \p cds::gc::DHP
        - \p Key - key type
        - \p T - value type to be stored in tree's leaf nodes.
        - \p Traits - map traits, default is \p ellen_bintree::traits
            It is possible to declare option-based tree with \p ellen_bintree::make_map_traits metafunction
            instead of \p Traits template argument.

        @note Do not include <tt><cds/container/impl/ellen_bintree_map.h></tt> header file directly.
        There are header file for each GC type:
        - <tt><cds/container/ellen_bintree_map_hp.h></tt> - for Hazard Pointer GC cds::gc::HP
        - <tt><cds/container/ellen_bintree_map_dhp.h></tt> - for Dynamic Hazard Pointer GC cds::gc::DHP
        - <tt><cds/container/ellen_bintree_map_rcu.h></tt> - for RCU GC
            (see \ref cds_container_EllenBinTreeMap_rcu "RCU-based EllenBinTreeMap")
    */
    template <
        class GC,
        typename Key,
        typename T,
#ifdef CDS_DOXYGEN_INVOKED
        class Traits = ellen_bintree::traits
#else
        class Traits
#endif
    >
    class EllenBinTreeMap
#ifdef CDS_DOXYGEN_INVOKED
        : public cds::intrusive::EllenBinTree< GC, Key, T, Traits >
#else
        : public ellen_bintree::details::make_ellen_bintree_map< GC, Key, T, Traits >::type
#endif
    {
        //@cond
        typedef ellen_bintree::details::make_ellen_bintree_map< GC, Key, T, Traits > maker;
        typedef typename maker::type base_class;
        //@endcond
    public:
        typedef GC      gc;          ///< Garbage collector
        typedef Key     key_type;    ///< type of a key stored in the map
        typedef T       mapped_type; ///< type of value stored in the map
        typedef std::pair< key_type const, mapped_type >    value_type  ;   ///< Key-value pair stored in leaf node of the mp
        typedef Traits  traits;      ///< Map traits 

#   ifdef CDS_DOXYGEN_INVOKED
        typedef implementation_defined key_comparator; ///< key compare functor based on \p Traits::compare and \p Traits::less
#   else
        typedef typename maker::intrusive_traits::compare   key_comparator;
#   endif
        typedef typename base_class::item_counter           item_counter; ///< Item counting policy
        typedef typename base_class::memory_model           memory_model; ///< Memory ordering, see \p cds::opt::memory_model
        typedef typename base_class::node_allocator         node_allocator_type; ///< allocator for maintaining internal node
        typedef typename base_class::stat                   stat;         ///< internal statistics type
        typedef typename traits::copy_policy                copy_policy;  ///< key copy policy
        typedef typename traits::back_off                   back_off;      ///< Back-off strategy

        typedef typename traits::allocator                  allocator_type;   ///< Allocator for leaf nodes
        typedef typename base_class::node_allocator         node_allocator;   ///< Internal node allocator
        typedef typename base_class::update_desc_allocator  update_desc_allocator; ///< Update descriptor allocator

    protected:
        //@cond
        typedef typename base_class::value_type         leaf_node;
        typedef typename base_class::internal_node      internal_node;
        typedef typename base_class::update_desc        update_desc;

        typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;

        typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator >    scoped_node_ptr;
        //@endcond

    public:
        /// Guarded pointer
        typedef cds::gc::guarded_ptr< gc, leaf_node, value_type, details::guarded_ptr_cast_set<leaf_node, value_type> > guarded_ptr;

    public:
        /// Default constructor
        EllenBinTreeMap()
            : base_class()
        {}

        /// Clears the map
        ~EllenBinTreeMap()
        {}

        /// Inserts new node with key and default value
        /**
            The function creates a node with \p key and default value, and then inserts the node created into the map.

            Preconditions:
            - The \ref key_type should be constructible from a value of type \p K.
                In trivial case, \p K is equal to \ref key_type.
            - The \ref mapped_type should be default-constructible.

            Returns \p true if inserting successful, \p false otherwise.
        */
        template <typename K>
        bool insert( K const& key )
        {
            return insert_key( key, [](value_type&){} );
        }

        /// Inserts new node
        /**
            The function creates a node with copy of \p val value
            and then inserts the node created into the map.

            Preconditions:
            - The \p key_type should be constructible from \p key of type \p K.
            - The \p value_type should be constructible from \p val of type \p V.

            Returns \p true if \p val is inserted into the map, \p false otherwise.
        */
        template <typename K, typename V>
        bool insert( K const& key, V const& val )
        {
            scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key, val ));
            if ( base_class::insert( *pNode ))
            {
                pNode.release();
                return true;
            }
            return false;
        }

        /// Inserts new node and initialize it by a functor
        /**
            This function inserts new node with key \p key and if inserting is successful then it calls
            \p func functor with signature
            \code
                struct functor {
                    void operator()( value_type& item );
                };
            \endcode

            The argument \p item of user-defined functor \p func is the reference
            to the map's item inserted:
                - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
                - <tt>item.second</tt> is a reference to item's value that may be changed.

            The key_type should be constructible from value of type \p K.

            The function allows to split creating of new item into two part:
            - create item from \p key;
            - insert new item into the map;
            - if inserting is successful, initialize the value of item by calling \p func functor

            This can be useful if complete initialization of object of \p value_type is heavyweight and
            it is preferable that the initialization should be completed only if inserting is successful.
        */
        template <typename K, typename Func>
        bool insert_key( const K& key, Func func )
        {
            scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
            if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { func( item.m_Value ); } )) {
                pNode.release();
                return true;
            }
            return false;
        }

        /// For key \p key inserts data of type \p value_type created in-place from \p args
        /**
            Returns \p true if inserting successful, \p false otherwise.
        */
        template <typename K, typename... Args>
        bool emplace( K&& key, Args&&... args )
        {
            scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
            if ( base_class::insert( *pNode )) {
                pNode.release();
                return true;
            }
            return false;
        }

        /// Ensures that the \p key exists in the map
        /**
            The operation performs inserting or changing data with lock-free manner.

            If the \p key not found in the map, then the new item created from \p key
            is inserted into the map (note that in this case the \ref key_type should be
            constructible from type \p K).
            Otherwise, the functor \p func is called with item found.
            The functor \p Func may be a function with signature:
            \code
                void func( bool bNew, value_type& item );
            \endcode
            or a functor:
            \code
                struct my_functor {
                    void operator()( bool bNew, value_type& item );
                };
            \endcode

            with arguments:
            - \p bNew - \p true if the item has been inserted, \p false otherwise
            - \p item - item of the list

            The functor may change any fields of the \p item.second that is \ref value_type.

            Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
            \p second is true if new item has been added or \p false if the item with \p key
            already is in the list.

            @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
        */
        template <typename K, typename Func>
        std::pair<bool, bool> ensure( K const& key, Func func )
        {
            scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
            std::pair<bool, bool> res = base_class::ensure( *pNode,
                [&func](bool bNew, leaf_node& item, leaf_node const& ){ func( bNew, item.m_Value ); }
            );
            if ( res.first && res.second )
                pNode.release();
            return res;
        }

        /// Delete \p key from the map
        /**\anchor cds_nonintrusive_EllenBinTreeMap_erase_val

            Return \p true if \p key is found and deleted, \p false otherwise
        */
        template <typename K>
        bool erase( K const& key )
        {
            return base_class::erase(key);
        }

        /// Deletes the item from the map using \p pred predicate for searching
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_val "erase(K const&)"
            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 map.
        */
        template <typename K, typename Less>
        bool erase_with( K const& key, Less pred )
        {
            CDS_UNUSED( pred );
            return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
        }

        /// Delete \p key from the map
        /** \anchor cds_nonintrusive_EllenBinTreeMap_erase_func

            The function searches an item with key \p key, calls \p f functor
            and deletes the item. If \p key is not found, the functor is not called.

            The functor \p Func interface:
            \code
            struct extractor {
                void operator()(value_type& item) { ... }
            };
            \endcode

            Return \p true if key is found and deleted, \p false otherwise
        */
        template <typename K, typename Func>
        bool erase( K const& key, Func f )
        {
            return base_class::erase( key, [&f]( leaf_node& node) { f( node.m_Value ); } );
        }

        /// Deletes the item from the map using \p pred predicate for searching
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_func "erase(K const&, Func)"
            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 map.
        */
        template <typename K, typename Less, typename Func>
        bool erase_with( K const& key, Less pred, Func f )
        {
            CDS_UNUSED( pred );
            return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
                [&f]( leaf_node& node) { f( node.m_Value ); } );
        }

        /// Extracts an item with minimal key from the map
        /**
            If the map is not empty, the function returns \p true, \p result contains a pointer to minimum value.
            If the map is empty, the function returns \p false, \p result is left unchanged.

            @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
            It means that the function gets leftmost leaf of the tree and tries to unlink it.
            During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
            So, the function returns the item with minimum key at the moment of tree traversing.

            The guarded pointer \p result prevents deallocation of returned item,
            see cds::gc::guarded_ptr for explanation.
            @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
        */
        bool extract_min( guarded_ptr& result )
        {
            return base_class::extract_min_( result.guard() );
        }

        /// Extracts an item with maximal key from the map
        /**
            If the map is not empty, the function returns \p true, \p result contains a pointer to maximal value.
            If the map is empty, the function returns \p false, \p result is left unchanged.

            @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
            It means that the function gets rightmost leaf of the tree and tries to unlink it.
            During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
            So, the function returns the item with maximum key at the moment of tree traversing.

            The guarded pointer \p result prevents deallocation of returned item,
            see cds::gc::guarded_ptr for explanation.
            @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
        */
        bool extract_max( guarded_ptr& result )
        {
            return base_class::extract_max_( result.guard() );
        }

        /// Extracts an item from the tree
        /** \anchor cds_nonintrusive_EllenBinTreeMap_extract
            The function searches an item with key equal to \p key in the tree,
            unlinks it, and returns pointer to an item found in \p result parameter.
            If the item  is not found the function returns \p false.

            The guarded pointer \p result prevents deallocation of returned item,
            see cds::gc::guarded_ptr for explanation.
            @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
        */
        template <typename Q>
        bool extract( guarded_ptr& result, Q const& key )
        {
            return base_class::extract_( result.guard(), key );
        }

        /// Extracts an item from the map using \p pred for searching
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_extract "extract(guarded_ptr&, Q const&)"
            but \p pred is used for key compare.
            \p Less has the interface like \p std::less.
            \p pred must imply the same element order as the comparator used for building the map.
        */
        template <typename Q, typename Less>
        bool extract_with( guarded_ptr& result, Q const& key, Less pred )
        {
            CDS_UNUSED( pred );
            return base_class::extract_with_( result.guard(), key,
                cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
        }

        /// Find the key \p key
        /** \anchor cds_nonintrusive_EllenBinTreeMap_find_cfunc

            The function searches the item with key equal to \p key and calls the functor \p f for item found.
            The interface of \p Func functor is:
            \code
            struct functor {
                void operator()( value_type& item );
            };
            \endcode
            where \p item is the item found.

            The functor may change \p item.second.

            The function returns \p true if \p key is found, \p false otherwise.
        */
        template <typename K, typename Func>
        bool find( K const& key, Func f )
        {
            return base_class::find( key, [&f](leaf_node& item, K const& ) { f( item.m_Value );});
        }

        /// Finds the key \p val using \p pred predicate for searching
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_cfunc "find(K const&, Func)"
            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 map.
        */
        template <typename K, typename Less, typename Func>
        bool find_with( K const& key, Less pred, Func f )
        {
            CDS_UNUSED( pred );
            return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
                [&f](leaf_node& item, K const& ) { f( item.m_Value );});
        }

        /// Find the key \p key
        /** \anchor cds_nonintrusive_EllenBinTreeMap_find_val

            The function searches the item with key equal to \p key
            and returns \p true if it is found, and \p false otherwise.
        */
        template <typename K>
        bool find( K const& key )
        {
            return base_class::find( key );
        }

        /// Finds the key \p val using \p pred predicate for searching
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_val "find(K const&)"
            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 map.
        */
        template <typename K, typename Less>
        bool find_with( K const& key, Less pred )
        {
            CDS_UNUSED( pred );
            return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
        }

        /// Finds \p key and returns the item found
        /** @anchor cds_nonintrusive_EllenBinTreeMap_get
            The function searches the item with key equal to \p key and returns the item found in \p result parameter.
            The function returns \p true if \p key is found, \p false otherwise.

            The guarded pointer \p result prevents deallocation of returned item,
            see cds::gc::guarded_ptr for explanation.
            @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
        */
        template <typename Q>
        bool get( guarded_ptr& result, Q const& key )
        {
            return base_class::get_( result.guard(), key );
        }

        /// Finds \p key with predicate \p pred and returns the item found
        /**
            The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_get "get(guarded_ptr&, Q const&)"
            but \p pred is used for key comparing.
            \p Less functor has the interface like \p std::less.
            \p pred must imply the same element order as the comparator used for building the map.
        */
        template <typename Q, typename Less>
        bool get_with( guarded_ptr& result, Q const& key, Less pred )
        {
            CDS_UNUSED( pred );
            return base_class::get_with_( result.guard(), key,
                cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
        }

        /// Clears the map (not atomic)
        void clear()
        {
            base_class::clear();
        }

        /// Checks if the map is empty
        /**
            Emptiness is checked by item counting: if item count is zero then the map is empty.
        */
        bool empty() const
        {
            return base_class::empty();
        }

        /// Returns item count in the set
        /**
            Only leaf nodes containing user data are counted.

            The value returned depends on item counter type provided by \p Traits template parameter.
            If it is \p atomicity::empty_item_counter this function always returns 0.

            The function is not suitable for checking the tree emptiness, use \p empty()
            member function for this purpose.
        */
        size_t size() const
        {
            return base_class::size();
        }

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

        /// Checks internal consistency (not atomic, not thread-safe)
        /**
            The debugging function to check internal consistency of the tree.
        */
        bool check_consistency() const
        {
            return base_class::check_consistency();
        }

    };
}} // namespace cds::container

#endif //#ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H