2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H
32 #define CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
39 /// Michael's ordered list fo key-value pair
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_MichaelKVList_gc
43 This is key-value variation of non-intrusive MichaelList.
44 Like standard container, this implementation split a value stored into two part -
45 constant key and alterable value.
47 Usually, ordered single-linked list is used as a building block for the hash table implementation.
48 The complexity of searching is <tt>O(N)</tt> where \p N is the item count in the list, not in the
52 - \p GC - garbage collector used
53 - \p Key - key type of an item stored in the list. It should be copy-constructible
54 - \p Value - value type stored in a list
55 - \p Traits - type traits, default is \p michael_list::traits
57 It is possible to declare option-based list with \p cds::container::michael_list::make_traits metafunction istead of \p Traits template
58 argument. For example, the following traits-based declaration of \p gc::HP Michael's list
60 #include <cds/container/michael_kvlist_hp.h>
61 // Declare comparator for the item
63 int operator ()( int i1, int i2 )
70 struct my_traits: public cds::container::michael_list::traits
72 typedef my_compare compare;
75 // Declare traits-based list
76 typedef cds::container::MichaelKVList< cds::gc::HP, int, int, my_traits > traits_based_list;
78 is equivalent for the following option-based list
80 #include <cds/container/michael_kvlist_hp.h>
82 // my_compare is the same
84 // Declare option-based list
85 typedef cds::container::MichaelKVList< cds::gc::HP, int, int,
86 typename cds::container::michael_list::make_traits<
87 cds::container::opt::compare< my_compare > // item comparator option
93 There are different specializations of this template for each garbage collecting schema used.
94 You should include appropriate .h-file depending on GC you are using:
95 - for gc::HP: \code #include <cds/container/michael_kvlist_hp.h> \endcode
96 - for gc::DHP: \code #include <cds/container/michael_kvlist_dhp.h> \endcode
97 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_kvlist_rcu.h> \endcode
98 - for gc::nogc: \code #include <cds/container/michael_kvlist_nogc.h> \endcode
104 #ifdef CDS_DOXYGEN_INVOKED
105 typename Traits = michael_list::traits
111 #ifdef CDS_DOXYGEN_INVOKED
112 protected intrusive::MichaelList< GC, implementation_defined, Traits >
114 protected details::make_michael_kvlist< GC, Key, Value, Traits >::type
118 typedef details::make_michael_kvlist< GC, Key, Value, Traits > maker;
119 typedef typename maker::type base_class;
123 #ifdef CDS_DOXYGEN_INVOKED
124 typedef Key key_type ; ///< Key type
125 typedef Value mapped_type ; ///< Type of value stored in the list
126 typedef std::pair<key_type const, mapped_type> value_type ; ///< key/value pair stored in the list
128 typedef typename maker::key_type key_type;
129 typedef typename maker::value_type mapped_type;
130 typedef typename maker::pair_type value_type;
133 typedef typename base_class::gc gc; ///< Garbage collector used
134 typedef typename base_class::back_off back_off; ///< Back-off strategy used
135 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
136 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
137 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
138 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
140 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
144 typedef typename base_class::value_type node_type;
145 typedef typename maker::cxx_allocator cxx_allocator;
146 typedef typename maker::node_deallocator node_deallocator;
147 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
149 typedef typename base_class::atomic_node_ptr head_type;
154 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_map<node_type, value_type> > guarded_ptr;
158 template <typename K>
159 static node_type * alloc_node(const K& key)
161 return cxx_allocator().New( key );
164 template <typename K, typename V>
165 static node_type * alloc_node( const K& key, const V& val )
167 return cxx_allocator().New( key, val );
170 template <typename K, typename... Args>
171 static node_type * alloc_node( K&& key, Args&&... args )
173 return cxx_allocator().MoveNew( std::forward<K>(key), std::forward<Args>(args)...);
176 static void free_node( node_type * pNode )
178 cxx_allocator().Delete( pNode );
181 struct node_disposer {
182 void operator()( node_type * pNode )
187 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
191 return base_class::m_pHead;
194 head_type const& head() const
196 return base_class::m_pHead;
202 template <bool IsConst>
203 class iterator_type: protected base_class::template iterator_type<IsConst>
205 typedef typename base_class::template iterator_type<IsConst> iterator_base;
207 iterator_type( head_type const& pNode )
208 : iterator_base( pNode )
211 friend class MichaelKVList;
214 typedef typename cds::details::make_const_type<mapped_type, IsConst>::reference value_ref;
215 typedef typename cds::details::make_const_type<mapped_type, IsConst>::pointer value_ptr;
217 typedef typename cds::details::make_const_type<value_type, IsConst>::reference pair_ref;
218 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer pair_ptr;
223 iterator_type( iterator_type const& src )
224 : iterator_base( src )
227 key_type const& key() const
229 typename iterator_base::value_ptr p = iterator_base::operator ->();
230 assert( p != nullptr );
231 return p->m_Data.first;
234 pair_ptr operator ->() const
236 typename iterator_base::value_ptr p = iterator_base::operator ->();
237 return p ? &(p->m_Data) : nullptr;
240 pair_ref operator *() const
242 typename iterator_base::value_ref p = iterator_base::operator *();
246 value_ref val() const
248 typename iterator_base::value_ptr p = iterator_base::operator ->();
249 assert( p != nullptr );
250 return p->m_Data.second;
254 iterator_type& operator ++()
256 iterator_base::operator ++();
261 bool operator ==(iterator_type<C> const& i ) const
263 return iterator_base::operator ==(i);
266 bool operator !=(iterator_type<C> const& i ) const
268 return iterator_base::operator !=(i);
276 The forward iterator for Michael's list has some features:
277 - it has no post-increment operator
278 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
279 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
280 may be thrown if a limit of guard count per thread is exceeded.
281 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
282 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
283 deleting operations it is no guarantee that you iterate all item in the list.
285 @warning Use this iterator on the concurrent container for debugging purpose only.
287 The iterator interface to access item data:
288 - <tt> operator -> </tt> - returns a pointer to \ref value_type for iterator
289 - <tt> operator *</tt> - returns a reference (a const reference for \p const_iterator) to \ref value_type for iterator
290 - <tt> const key_type& key() </tt> - returns a key reference for iterator
291 - <tt> mapped_type& val() </tt> - retuns a value reference for iterator (const reference for \p const_iterator)
293 For both functions the iterator should not be equal to <tt> end() </tt>
295 typedef iterator_type<false> iterator;
297 /// Const forward iterator
299 For iterator's features and requirements see \ref iterator
301 typedef iterator_type<true> const_iterator;
303 ///@name Forward iterators (only for debugging purpose)
305 /// Returns a forward iterator addressing the first element in a list
307 For empty list \code begin() == end() \endcode
311 return iterator( head() );
314 /// Returns an iterator that addresses the location succeeding the last element in a list
316 Do not use the value returned by <tt>end</tt> function to access any item.
317 Internally, <tt>end</tt> returning value equals to \p nullptr.
319 The returned value can be used only to control reaching the end of the list.
320 For empty list \code begin() == end() \endcode
327 /// Returns a forward const iterator addressing the first element in a list
328 const_iterator begin() const
330 return const_iterator( head() );
333 /// Returns a forward const iterator addressing the first element in a list
334 const_iterator cbegin() const
336 return const_iterator( head() );
339 /// Returns an const iterator that addresses the location succeeding the last element in a list
340 const_iterator end() const
342 return const_iterator();
345 /// Returns an const iterator that addresses the location succeeding the last element in a list
346 const_iterator cend() const
348 return const_iterator();
353 /// Default constructor
355 Initializes empty list
369 /// Inserts new node with key and default value
371 The function creates a node with \p key and default value, and then inserts the node created into the list.
374 - The \p key_type should be constructible from value of type \p K.
375 In trivial case, \p K is equal to \p key_type.
376 - The \p mapped_type should be default-constructible.
378 Returns \p true if inserting successful, \p false otherwise.
380 template <typename K>
381 bool insert( const K& key )
383 return insert_at( head(), key );
386 /// Inserts new node with a key and a value
388 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
391 - The \p key_type should be constructible from \p key of type \p K.
392 - The \p mapped_type should be constructible from \p val of type \p V.
394 Returns \p true if inserting successful, \p false otherwise.
396 template <typename K, typename V>
397 bool insert( const K& key, const V& val )
399 // We cannot use insert with functor here
400 // because we cannot lock inserted node for updating
401 // Therefore, we use separate function
402 return insert_at( head(), key, val );
405 /// Inserts new node and initialize it by a functor
407 This function inserts new node with key \p key and if inserting is successful then it calls
408 \p func functor with signature
411 void operator()( value_type& item );
415 The argument \p item of user-defined functor \p func is the reference
416 to the item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
417 User-defined functor \p func should guarantee that during changing item's value no any other changes
418 could be made on this list's item by concurrent threads.
419 The user-defined functor is called only if inserting is successful.
421 The \p key_type should be constructible from value of type \p K.
423 The function allows to split creating of new item into two part:
424 - create a new item from \p key;
425 - insert the new item into the list;
426 - if inserting is successful, initialize the value of item by calling \p func functor
428 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
429 it is preferable that the initialization should be completed only if inserting is successful.
431 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
433 template <typename K, typename Func>
434 bool insert_with( const K& key, Func func )
436 return insert_with_at( head(), key, func );
439 /// Updates data by \p key
441 The operation performs inserting or replacing the element with lock-free manner.
443 If the \p key not found in the list, then the new item created from \p key
444 will be inserted iff \p bAllowInsert is \p true.
445 (note that in this case the \ref key_type should be constructible from type \p K).
446 Otherwise, if \p key is found, the functor \p func is called with item found.
448 The functor \p Func signature is:
451 void operator()( bool bNew, value_type& item );
455 - \p bNew - \p true if the item has been inserted, \p false otherwise
456 - \p item - the item found or inserted
458 The functor may change any fields of the \p item.second of \p mapped_type;
459 however, \p func must guarantee that during changing no any other modifications
460 could be made on this item by concurrent threads.
462 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
463 \p second is true if new item has been added or \p false if the item with \p key
466 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
468 template <typename K, typename Func>
469 std::pair<bool, bool> update( K const& key, Func f, bool bAllowInsert = true )
471 return update_at( head(), key, f, bAllowInsert );
474 template <typename K, typename Func>
475 CDS_DEPRECATED("ensure() is deprecated, use update()")
476 std::pair<bool, bool> ensure( K const& key, Func f )
478 return update( key, f, true );
482 /// Inserts a new node using move semantics
484 \p key_type field of new item is constructed from \p key argument,
485 \p mapped_type field is done from \p args.
487 Returns \p true if inserting successful, \p false otherwise.
489 template <typename K, typename... Args>
490 bool emplace( K&& key, Args&&... args )
492 return emplace_at( head(), std::forward<K>(key), std::forward<Args>(args)... );
495 /// Deletes \p key from the list
496 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_val
498 Returns \p true if \p key is found and has been deleted, \p false otherwise
500 template <typename K>
501 bool erase( K const& key )
503 return erase_at( head(), key, intrusive_key_comparator() );
506 /// Deletes the item from the list using \p pred predicate for searching
508 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_val "erase(K const&)"
509 but \p pred is used for key comparing.
510 \p Less functor has the interface like \p std::less.
511 \p pred must imply the same element order as the comparator used for building the list.
513 template <typename K, typename Less>
514 bool erase_with( K const& key, Less pred )
517 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type() );
520 /// Deletes \p key from the list
521 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_func
522 The function searches an item with key \p key, calls \p f functor
523 and deletes the item. If \p key is not found, the functor is not called.
525 The functor \p Func interface:
528 void operator()(value_type& val) { ... }
532 Return \p true if key is found and deleted, \p false otherwise
536 template <typename K, typename Func>
537 bool erase( K const& key, Func f )
539 return erase_at( head(), key, intrusive_key_comparator(), f );
542 /// Deletes the item from the list using \p pred predicate for searching
544 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_func "erase(K const&, Func)"
545 but \p pred is used for key comparing.
546 \p Less functor has the interface like \p std::less.
547 \p pred must imply the same element order as the comparator used for building the list.
549 template <typename K, typename Less, typename Func>
550 bool erase_with( K const& key, Less pred, Func f )
553 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
556 /// Extracts the item from the list with specified \p key
557 /** \anchor cds_nonintrusive_MichaelKVList_hp_extract
558 The function searches an item with key equal to \p key,
559 unlinks it from the list, and returns it as \p guarded_ptr.
560 If \p key is not found the function returns an empty guarded pointer.
562 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
564 The \p disposer specified in \p Traits class template parameter is called automatically
565 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
566 will be destroyed or released.
567 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
571 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
575 ord_list::guarded_ptr gp(theList.extract( 5 ));
580 // Destructor of gp releases internal HP guard
584 template <typename K>
585 guarded_ptr extract( K const& key )
588 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
592 /// Extracts the item from the list with comparing functor \p pred
594 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_extract "extract(K const&)"
595 but \p pred predicate is used for key comparing.
597 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
599 \p pred must imply the same element order as the comparator used for building the list.
601 template <typename K, typename Less>
602 guarded_ptr extract_with( K const& key, Less pred )
606 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
610 /// Checks whether the list contains \p key
612 The function searches the item with key equal to \p key
613 and returns \p true if it is found, and \p false otherwise.
615 template <typename Q>
616 bool contains( Q const& key )
618 return find_at( head(), key, intrusive_key_comparator() );
621 template <typename Q>
622 CDS_DEPRECATED("deprecated, use contains()")
623 bool find( Q const& key )
625 return contains( key );
629 /// Checks whether the map contains \p key using \p pred predicate for searching
631 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
632 \p Less functor has the interface like \p std::less.
633 \p Less must imply the same element order as the comparator used for building the list.
635 template <typename Q, typename Less>
636 bool contains( Q const& key, Less pred )
639 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
642 template <typename Q, typename Less>
643 CDS_DEPRECATED("deprecated, use contains()")
644 bool find_with( Q const& key, Less pred )
647 return contains( key, pred );
651 /// Finds the key \p key and performs an action with it
652 /** \anchor cds_nonintrusive_MichaelKVList_hp_find_func
653 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
654 The interface of \p Func functor is:
657 void operator()( value_type& item );
660 where \p item is the item found.
662 The functor may change <tt>item.second</tt> that is reference to value of node.
663 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
664 The function does not serialize simultaneous access to the list \p item. If such access is
665 possible you must provide your own synchronization schema to exclude unsafe item modifications.
667 The function returns \p true if \p key is found, \p false otherwise.
669 template <typename Q, typename Func>
670 bool find( Q const& key, Func f )
672 return find_at( head(), key, intrusive_key_comparator(), f );
675 /// Finds the key \p val using \p pred predicate for searching
677 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_find_func "find(Q&, Func)"
678 but \p pred is used for key comparing.
679 \p Less functor has the interface like \p std::less.
680 \p pred must imply the same element order as the comparator used for building the list.
682 template <typename Q, typename Less, typename Func>
683 bool find_with( Q const& key, Less pred, Func f )
686 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
689 /// Finds the \p key and return the item found
690 /** \anchor cds_nonintrusive_MichaelKVList_hp_get
691 The function searches the item with key equal to \p key
692 and returns it as \p guarded_ptr.
693 If \p key is not found the function returns an empty guarded pointer.
695 The \p disposer specified in \p Traits class template parameter is called
696 by garbage collector \p GC automatically when returned \p guarded_ptr object
697 will be destroyed or released.
698 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
702 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
706 ord_list::guarded_ptr gp(theList.get( 5 ));
711 // Destructor of guarded_ptr releases internal HP guard
715 Note the compare functor specified for class \p Traits template parameter
716 should accept a parameter of type \p K that can be not the same as \p key_type.
718 template <typename K>
719 guarded_ptr get( K const& key )
722 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
726 /// Finds the \p key and return the item found
728 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_get "get( guarded_ptr& ptr, K const&)"
729 but \p pred is used for comparing the keys.
731 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
733 \p pred must imply the same element order as the comparator used for building the list.
735 template <typename K, typename Less>
736 guarded_ptr get_with( K const& key, Less pred )
740 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
744 /// Checks if the list is empty
747 return base_class::empty();
750 /// Returns list's item count
752 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
753 this function always returns 0.
755 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
756 is empty. To check list emptyness use \p empty() method.
760 return base_class::size();
771 bool insert_node_at( head_type& refHead, node_type * pNode )
773 assert( pNode != nullptr );
774 scoped_node_ptr p( pNode );
775 if ( base_class::insert_at( refHead, *pNode )) {
782 template <typename K>
783 bool insert_at( head_type& refHead, const K& key )
785 return insert_node_at( refHead, alloc_node( key ));
788 template <typename K, typename V>
789 bool insert_at( head_type& refHead, const K& key, const V& val )
791 return insert_node_at( refHead, alloc_node( key, val ));
794 template <typename K, typename Func>
795 bool insert_with_at( head_type& refHead, const K& key, Func f )
797 scoped_node_ptr pNode( alloc_node( key ));
799 if ( base_class::insert_at( refHead, *pNode, [&f](node_type& node){ f( node.m_Data ); })) {
806 template <typename K, typename... Args>
807 bool emplace_at( head_type& refHead, K&& key, Args&&... args )
809 return insert_node_at( refHead, alloc_node( std::forward<K>(key), std::forward<Args>(args)... ));
812 template <typename K, typename Func>
813 std::pair<bool, bool> update_at( head_type& refHead, const K& key, Func f, bool bAllowInsert )
815 scoped_node_ptr pNode( alloc_node( key ));
817 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
818 [&f]( bool bNew, node_type& node, node_type& ){ f( bNew, node.m_Data ); },
820 if ( ret.first && ret.second )
826 template <typename K, typename Compare>
827 bool erase_at( head_type& refHead, K const& key, Compare cmp )
829 return base_class::erase_at( refHead, key, cmp );
832 template <typename K, typename Compare, typename Func>
833 bool erase_at( head_type& refHead, K const& key, Compare cmp, Func f )
835 return base_class::erase_at( refHead, key, cmp, [&f]( node_type const & node ){ f( const_cast<value_type&>(node.m_Data)); });
837 template <typename K, typename Compare>
838 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
840 return base_class::extract_at( refHead, guard, key, cmp );
843 template <typename K, typename Compare>
844 bool find_at( head_type& refHead, K const& key, Compare cmp )
846 return base_class::find_at( refHead, key, cmp );
849 template <typename K, typename Compare, typename Func>
850 bool find_at( head_type& refHead, K& key, Compare cmp, Func f )
852 return base_class::find_at( refHead, key, cmp, [&f](node_type& node, K const&){ f( node.m_Data ); });
855 template <typename K, typename Compare>
856 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
858 return base_class::get_at( refHead, guard, key, cmp );
864 }} // namespace cds::container
866 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H