3 #ifndef CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H
4 #define CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H
6 #include <cds/intrusive/details/michael_list_base.h>
7 #include <cds/details/make_const_type.h>
9 namespace cds { namespace intrusive {
11 /// Michael's lock-free ordered single-linked list
12 /** @ingroup cds_intrusive_list
13 \anchor cds_intrusive_MichaelList_hp
15 Usually, ordered single-linked list is used as a building block for the hash table implementation.
16 The complexity of searching is <tt>O(N)</tt>.
19 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
22 - \p GC - Garbage collector used. Note the \p GC must be the same as the GC used for item type \p T (see \p michael_list::node).
23 - \p T - type to be stored in the list. The type must be based on \p michael_list::node (for \p michael_list::base_hook)
24 or it must have a member of type \p michael_list::node (for \p michael_list::member_hook).
25 - \p Traits - type traits, default is \p michael_list::traits. It is possible to declare option-based
26 list with \p cds::intrusive::michael_list::make_traits metafunction:
27 For example, the following traits-based declaration of \p gc::HP Michael's list
29 #include <cds/intrusive/michael_list_hp.h>
30 // Declare item stored in your list
31 struct item: public cds::intrusive::michael_list::node< cds::gc::HP >
37 // Declare comparator for the item
39 int operator()( item const& i1, item const& i2 ) const
41 return i1.nKey - i2.nKey;
46 struct my_traits: public cds::intrusive::michael_list::traits
48 typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > hook;
49 typedef my_compare compare;
52 // Declare traits-based list
53 typedef cds::intrusive::MichaelList< cds::gc::HP, item, my_traits > traits_based_list;
55 is equivalent for the following option-based list
57 #include <cds/intrusive/michael_list_hp.h>
59 // item struct and my_compare are the same
61 // Declare option-based list
62 typedef cds::intrusive::MichaelList< cds::gc::HP, item,
63 typename cds::intrusive::michael_list::make_traits<
64 cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > > // hook option
65 ,cds::intrusive::opt::compare< my_compare > // item comparator option
71 There are different specializations of this template for each garbage collecting schema.
72 You should select GC needed and include appropriate .h-file:
73 - for \p gc::HP: <tt> <cds/intrusive/michael_list_hp.h> </tt>
74 - for \p gc::DHP: <tt> <cds/intrusive/michael_list_dhp.h> </tt>
75 - for \ref cds_urcu_gc "RCU type" - see \ref cds_intrusive_MichaelList_rcu "RCU-based MichaelList"
76 - for \p gc::nogc: <tt> <cds/intrusive/michael_list_nogc.h> </tt>
77 See \ref cds_intrusive_MichaelList_nogc "non-GC MichaelList"
79 Then, you should incorporate \p michael_list::node into your struct \p T and provide
80 appropriate \p michael_list::traits::hook in your \p Traits template parameters. Usually, for \p Traits you
81 define a struct based on \p michael_list::traits.
83 Example for \p gc::DHP and base hook:
85 // Include GC-related Michael's list specialization
86 #include <cds/intrusive/michael_list_dhp.h>
88 // Data stored in Michael's list
89 struct my_data: public cds::intrusive::michael_list::node< cds::gc::DHP >
98 // my_data comparing functor
100 int operator()( const my_data& d1, const my_data& d2 )
102 return d1.strKey.compare( d2.strKey );
105 int operator()( const my_data& d, const std::string& s )
107 return d.strKey.compare(s);
110 int operator()( const std::string& s, const my_data& d )
112 return s.compare( d.strKey );
118 struct my_traits: public cds::intrusive::michael_list::traits
120 typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::DHP > > hook;
121 typedef my_data_cmp compare;
125 typedef cds::intrusive::MichaelList< cds::gc::DHP, my_data, my_traits > traits_based_list;
128 Equivalent option-based code:
130 // GC-related specialization
131 #include <cds/intrusive/michael_list_dhp.h>
140 // Declare option-based list
141 typedef cds::intrusive::MichaelList< cds::gc::DHP
143 , typename cds::intrusive::michael_list::make_traits<
144 cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::DHP > > >
145 ,cds::intrusive::opt::compare< my_data_cmp >
154 #ifdef CDS_DOXYGEN_INVOKED
155 ,class Traits = michael_list::traits
163 typedef T value_type; ///< type of value stored in the list
164 typedef Traits traits; ///< Traits template parameter
166 typedef typename traits::hook hook; ///< hook type
167 typedef typename hook::node_type node_type; ///< node type
169 # ifdef CDS_DOXYGEN_INVOKED
170 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
172 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
175 typedef typename traits::disposer disposer; ///< disposer used
176 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
177 typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
179 typedef GC gc ; ///< Garbage collector
180 typedef typename traits::back_off back_off; ///< back-off strategy
181 typedef typename traits::item_counter item_counter; ///< Item counting policy used
182 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
184 typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
187 // Rebind traits (split-list support)
188 template <typename... Options>
189 struct rebind_traits {
193 , typename cds::opt::make_options< traits, Options...>::type
199 typedef typename node_type::atomic_marked_ptr atomic_node_ptr; ///< Atomic node pointer
200 typedef typename node_type::marked_ptr marked_node_ptr; ///< Node marked pointer
202 typedef atomic_node_ptr auxiliary_head; ///< Auxiliary head type (for split-list support)
204 atomic_node_ptr m_pHead; ///< Head pointer
205 item_counter m_ItemCounter; ///< Item counter
208 /// Position pointer for item search
210 atomic_node_ptr * pPrev ; ///< Previous node
211 node_type * pCur ; ///< Current node
212 node_type * pNext ; ///< Next node
214 typename gc::template GuardArray<3> guards ; ///< Guards array
223 struct clean_disposer {
224 void operator()( value_type * p )
226 michael_list::node_cleaner<gc, node_type, memory_model>()( node_traits::to_node_ptr( p ));
234 static void retire_node( node_type * pNode )
236 assert( pNode != nullptr );
237 gc::template retire<clean_disposer>( node_traits::to_value_ptr( *pNode ));
240 static bool link_node( node_type * pNode, position& pos )
242 assert( pNode != nullptr );
243 link_checker::is_empty( pNode );
245 marked_node_ptr cur(pos.pCur);
246 pNode->m_pNext.store( cur, memory_model::memory_order_release );
247 return pos.pPrev->compare_exchange_strong( cur, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed );
250 static bool unlink_node( position& pos )
252 assert( pos.pPrev != nullptr );
253 assert( pos.pCur != nullptr );
255 // Mark the node (logical deleting)
256 marked_node_ptr next(pos.pNext, 0);
257 if ( pos.pCur->m_pNext.compare_exchange_strong( next, marked_node_ptr(pos.pNext, 1), memory_model::memory_order_release, atomics::memory_order_relaxed )) {
258 // physical deletion may be performed by search function if it detects that a node is logically deleted (marked)
259 // CAS may be successful here or in other thread that searching something
260 marked_node_ptr cur(pos.pCur);
261 if ( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr( pos.pNext ), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))
262 retire_node( pos.pCur );
271 template <bool IsConst>
274 friend class MichaelList;
277 value_type * m_pNode;
278 typename gc::Guard m_Guard;
283 typename gc::Guard g;
284 node_type * pCur = node_traits::to_node_ptr( *m_pNode );
286 marked_node_ptr pNext;
288 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed);
289 g.assign( node_traits::to_value_ptr( pNext.ptr()));
290 } while ( pNext != pCur->m_pNext.load(memory_model::memory_order_acquire));
293 m_pNode = m_Guard.assign( g.template get<value_type>());
301 iterator_type( atomic_node_ptr const& pNode )
304 marked_node_ptr p = pNode.load(memory_model::memory_order_relaxed);
306 m_pNode = m_Guard.assign( node_traits::to_value_ptr( p.ptr()));
312 if ( p == pNode.load(memory_model::memory_order_acquire))
318 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
319 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
325 iterator_type( iterator_type const& src )
328 m_pNode = m_Guard.assign( src.m_pNode );
334 value_ptr operator ->() const
339 value_ref operator *() const
341 assert( m_pNode != nullptr );
346 iterator_type& operator ++()
352 iterator_type& operator = (iterator_type const& src)
354 m_pNode = src.m_pNode;
355 m_Guard.assign( m_pNode );
361 void operator ++(int)
368 bool operator ==(iterator_type<C> const& i ) const
370 return m_pNode == i.m_pNode;
373 bool operator !=(iterator_type<C> const& i ) const
375 return m_pNode != i.m_pNode;
383 The forward iterator for Michael's list has some features:
384 - it has no post-increment operator
385 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
386 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
387 may be thrown if the limit of guard count per thread is exceeded.
388 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
389 - Iterator ensures thread-safety even if you delete the item the iterator points to. However, in case of concurrent
390 deleting operations there is no guarantee that you iterate all item in the list.
392 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
393 for debug purpose only.
395 The iterator interface:
399 // Default constructor
403 iterator( iterator const& src );
405 // Dereference operator
406 value_type * operator ->() const;
408 // Dereference operator
409 value_type& operator *() const;
411 // Preincrement operator
412 iterator& operator ++();
414 // Assignment operator
415 iterator& operator = (iterator const& src);
417 // Equality operators
418 bool operator ==(iterator const& i ) const;
419 bool operator !=(iterator const& i ) const;
423 typedef iterator_type<false> iterator;
424 /// Const forward iterator
426 For iterator's features and requirements see \ref iterator
428 typedef iterator_type<true> const_iterator;
430 /// Returns a forward iterator addressing the first element in a list
432 For empty list \code begin() == end() \endcode
436 return iterator( m_pHead );
439 /// Returns an iterator that addresses the location succeeding the last element in a list
441 Do not use the value returned by <tt>end</tt> function to access any item.
442 Internally, <tt>end</tt> returning value equals to \p nullptr.
444 The returned value can be used only to control reaching the end of the list.
445 For empty list <tt>begin() == end()</tt>
452 /// Returns a forward const iterator addressing the first element in a list
453 const_iterator cbegin() const
455 return const_iterator( m_pHead );
458 /// Returns a forward const iterator addressing the first element in a list
459 const_iterator begin() const
461 return const_iterator( m_pHead );
464 /// Returns an const iterator that addresses the location succeeding the last element in a list
465 const_iterator end() const
467 return const_iterator();
470 /// Returns an const iterator that addresses the location succeeding the last element in a list
471 const_iterator cend() const
473 return const_iterator();
477 /// Default constructor initializes empty list
481 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
484 /// Destroys the list object
492 The function inserts \p val into the list if the list does not contain
493 an item with key equal to \p val.
495 Returns \p true if \p val has been linked to the list, \p false otherwise.
497 bool insert( value_type& val )
499 return insert_at( m_pHead, val );
504 This function is intended for derived non-intrusive containers.
506 The function allows to split new item creating into two part:
507 - create item with key only
508 - insert new item into the list
509 - if inserting is success, calls \p f functor to initialize value-field of \p val.
511 The functor signature is:
513 void func( value_type& val );
515 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
516 \p val no any other changes could be made on this list's item by concurrent threads.
517 The user-defined functor is called only if the inserting is success.
519 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
521 template <typename Func>
522 bool insert( value_type& val, Func f )
524 return insert_at( m_pHead, val, f );
529 The operation performs inserting or changing data with lock-free manner.
531 If the item \p val is not found in the list, then \p val is inserted
532 iff \p bInsert is \p true.
533 Otherwise, the functor \p func is called with item found.
534 The functor signature is:
536 void func( bool bNew, value_type& item, value_type& val );
539 - \p bNew - \p true if the item has been inserted, \p false otherwise
540 - \p item - item of the list
541 - \p val - argument \p val passed into the \p update() function
542 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
543 refers to the same thing.
545 The functor may change non-key fields of the \p item; however, \p func must guarantee
546 that during changing no any other modifications could be made on this item by concurrent threads.
548 Returns std::pair<bool, bool> where \p first is \p true if operation is successfull,
549 \p second is \p true if new item has been added or \p false if the item with \p key
550 already is in the list.
552 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
554 template <typename Func>
555 std::pair<bool, bool> update( value_type& val, Func func, bool bInsert = true )
557 return update_at( m_pHead, val, func, bInsert );
561 template <typename Func>
562 CDS_DEPRECATED("ensure() is deprecated, use update()")
563 std::pair<bool, bool> ensure( value_type& val, Func func )
565 return update( val, func, true );
569 /// Unlinks the item \p val from the list
571 The function searches the item \p val in the list and unlinks it from the list
572 if it is found and it is equal to \p val.
574 Difference between \p erase() and \p %unlink(): \p %erase() finds <i>a key</i>
575 and deletes the item found. \p %unlink() finds an item by key and deletes it
576 only if \p val is an item of the list, i.e. the pointer to item found
577 is equal to <tt> &val </tt>.
579 The function returns \p true if success and \p false otherwise.
581 bool unlink( value_type& val )
583 return unlink_at( m_pHead, val );
586 /// Deletes the item from the list
587 /** \anchor cds_intrusive_MichaelList_hp_erase_val
588 The function searches an item with key equal to \p key in the list,
589 unlinks it from the list, and returns \p true.
590 If \p key is not found the function return \p false.
592 template <typename Q>
593 bool erase( Q const& key )
595 return erase_at( m_pHead, key, key_comparator());
598 /// Deletes the item from the list using \p pred predicate for searching
600 The function is an analog of \ref cds_intrusive_MichaelList_hp_erase_val "erase(Q const&)"
601 but \p pred is used for key comparing.
602 \p Less functor has the interface like \p std::less.
603 \p pred must imply the same element order as the comparator used for building the list.
605 template <typename Q, typename Less>
606 bool erase_with( Q const& key, Less pred )
609 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
612 /// Deletes the item from the list
613 /** \anchor cds_intrusive_MichaelList_hp_erase_func
614 The function searches an item with key equal to \p key in the list,
615 call \p func functor with item found, unlinks it from the list, and returns \p true.
616 The \p Func interface is
619 void operator()( value_type const& item );
622 If \p key is not found the function return \p false, \p func is not called.
624 template <typename Q, typename Func>
625 bool erase( Q const& key, Func func )
627 return erase_at( m_pHead, key, key_comparator(), func );
630 /// Deletes the item from the list using \p pred predicate for searching
632 The function is an analog of \ref cds_intrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
633 but \p pred is used for key comparing.
634 \p Less functor has the interface like \p std::less.
635 \p pred must imply the same element order as the comparator used for building the list.
637 template <typename Q, typename Less, typename Func>
638 bool erase_with( Q const& key, Less pred, Func f )
641 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
644 /// Extracts the item from the list with specified \p key
645 /** \anchor cds_intrusive_MichaelList_hp_extract
646 The function searches an item with key equal to \p key,
647 unlinks it from the list, and returns it as \p guarded_ptr.
648 If \p key is not found returns an empty guarded pointer.
650 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
652 The \ref disposer specified in \p Traits class template parameter is called automatically
653 by garbage collector \p GC when returned \ref guarded_ptr object will be destroyed or released.
654 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
658 typedef cds::intrusive::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
662 ord_list::guarded_ptr gp(theList.extract( 5 ));
667 // Destructor of gp releases internal HP guard
671 template <typename Q>
672 guarded_ptr extract( Q const& key )
675 extract_at( m_pHead, gp.guard(), key, key_comparator());
679 /// Extracts the item using compare functor \p pred
681 The function is an analog of \ref cds_intrusive_MichaelList_hp_extract "extract(Q const&)"
682 but \p pred predicate is used for key comparing.
684 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
686 \p pred must imply the same element order as the comparator used for building the list.
688 template <typename Q, typename Less>
689 guarded_ptr extract_with( Q const& key, Less pred )
693 extract_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
697 /// Finds \p key in the list
698 /** \anchor cds_intrusive_MichaelList_hp_find_func
699 The function searches the item with key equal to \p key and calls the functor \p f for item found.
700 The interface of \p Func functor is:
703 void operator()( value_type& item, Q& key );
706 where \p item is the item found, \p key is the <tt>find</tt> function argument.
708 The functor may change non-key fields of \p item. Note that the function is only guarantee
709 that \p item cannot be disposed during functor is executing.
710 The function does not serialize simultaneous access to the \p item. If such access is
711 possible you must provide your own synchronization schema to keep out unsafe item modifications.
713 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
714 may modify both arguments.
716 The function returns \p true if \p val is found, \p false otherwise.
718 template <typename Q, typename Func>
719 bool find( Q& key, Func f )
721 return find_at( m_pHead, key, key_comparator(), f );
724 template <typename Q, typename Func>
725 bool find( Q const& key, Func f )
727 return find_at( m_pHead, key, key_comparator(), f );
731 /// Finds the \p key using \p pred predicate for searching
733 The function is an analog of \ref cds_intrusive_MichaelList_hp_find_func "find(Q&, Func)"
734 but \p pred is used for key comparing.
735 \p Less functor has the interface like \p std::less.
736 \p pred must imply the same element order as the comparator used for building the list.
738 template <typename Q, typename Less, typename Func>
739 bool find_with( Q& key, Less pred, Func f )
742 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
745 template <typename Q, typename Less, typename Func>
746 bool find_with( Q const& key, Less pred, Func f )
749 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
753 /// Checks whether the list contains \p key
755 The function searches the item with key equal to \p key
756 and returns \p true if it is found, and \p false otherwise.
758 template <typename Q>
759 bool contains( Q const& key )
761 return find_at( m_pHead, key, key_comparator());
764 template <typename Q>
765 CDS_DEPRECATED("deprecated, use contains()")
766 bool find( Q const& key )
768 return contains( key );
772 /// Checks whether the list contains \p key using \p pred predicate for searching
774 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
775 \p Less functor has the interface like \p std::less.
776 \p Less must imply the same element order as the comparator used for building the list.
778 template <typename Q, typename Less>
779 bool contains( Q const& key, Less pred )
782 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
785 template <typename Q, typename Less>
786 CDS_DEPRECATED("deprecated, use contains()")
787 bool find_with( Q const& key, Less pred )
789 return contains( key, pred );
793 /// Finds the \p key and return the item found
794 /** \anchor cds_intrusive_MichaelList_hp_get
795 The function searches the item with key equal to \p key
796 and returns it as \p guarded_ptr.
797 If \p key is not found the function returns an empty guarded pointer.
799 The \ref disposer specified in \p Traits class template parameter is called
800 by garbage collector \p GC automatically when returned \ref guarded_ptr object
801 will be destroyed or released.
802 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
806 typedef cds::intrusive::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
810 ord_list::guarded_ptr gp(theList.get( 5 ));
815 // Destructor of guarded_ptr releases internal HP guard
819 Note the compare functor specified for \p Traits template parameter
820 should accept a parameter of type \p Q that can be not the same as \p value_type.
822 template <typename Q>
823 guarded_ptr get( Q const& key )
826 get_at( m_pHead, gp.guard(), key, key_comparator());
830 /// Finds the \p key and return the item found
832 The function is an analog of \ref cds_intrusive_MichaelList_hp_get "get( Q const&)"
833 but \p pred is used for comparing the keys.
835 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
837 \p pred must imply the same element order as the comparator used for building the list.
839 template <typename Q, typename Less>
840 guarded_ptr get_with( Q const& key, Less pred )
844 get_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
850 The function unlink all items from the list.
854 typename gc::Guard guard;
855 marked_node_ptr head;
857 head = m_pHead.load(memory_model::memory_order_relaxed);
859 guard.assign( node_traits::to_value_ptr( *head.ptr()));
860 if ( m_pHead.load(memory_model::memory_order_acquire) == head ) {
861 if ( head.ptr() == nullptr )
863 value_type& val = *node_traits::to_value_ptr( *head.ptr());
869 /// Checks whether the list is empty
872 return m_pHead.load( memory_model::memory_order_relaxed ).all() == nullptr;
875 /// Returns list's item count
877 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
878 this function always returns 0.
880 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
881 is empty. To check list emptyness use \p empty() method.
885 return m_ItemCounter.value();
890 // split-list support
891 bool insert_aux_node( node_type * pNode )
893 return insert_aux_node( m_pHead, pNode );
896 // split-list support
897 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
899 assert( pNode != nullptr );
901 // Hack: convert node_type to value_type.
902 // In principle, auxiliary node can be non-reducible to value_type
903 // We assume that comparator can correctly distinguish aux and regular node.
904 return insert_at( refHead, *node_traits::to_value_ptr( pNode ));
907 bool insert_at( atomic_node_ptr& refHead, value_type& val )
909 node_type * pNode = node_traits::to_node_ptr( val );
910 link_checker::is_empty( pNode );
914 if ( search( refHead, val, pos, key_comparator()))
917 if ( link_node( pNode, pos )) {
923 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
927 template <typename Func>
928 bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
930 node_type * pNode = node_traits::to_node_ptr( val );
931 link_checker::is_empty( pNode );
935 if ( search( refHead, val, pos, key_comparator()))
938 typename gc::Guard guard;
939 guard.assign( &val );
940 if ( link_node( pNode, pos )) {
947 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
951 template <typename Func>
952 std::pair<bool, bool> update_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bInsert )
956 node_type * pNode = node_traits::to_node_ptr( val );
958 if ( search( refHead, val, pos, key_comparator())) {
959 if ( pos.pCur->m_pNext.load(memory_model::memory_order_acquire).bits()) {
961 continue; // the node found is marked as deleted
963 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur )) == 0 );
965 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
966 return std::make_pair( true, false );
970 return std::make_pair( false, false );
972 typename gc::Guard guard;
973 guard.assign( &val );
974 if ( link_node( pNode, pos )) {
976 func( true, val, val );
977 return std::make_pair( true, true );
980 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
985 bool unlink_at( atomic_node_ptr& refHead, value_type& val )
990 while ( search( refHead, val, pos, key_comparator())) {
991 if ( node_traits::to_value_ptr( *pos.pCur ) == &val ) {
992 if ( unlink_node( pos )) {
1005 template <typename Q, typename Compare, typename Func>
1006 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f, position& pos )
1009 while ( search( refHead, val, pos, cmp )) {
1010 if ( unlink_node( pos )) {
1011 f( *node_traits::to_value_ptr( *pos.pCur ));
1021 template <typename Q, typename Compare, typename Func>
1022 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f )
1025 return erase_at( refHead, val, cmp, f, pos );
1028 template <typename Q, typename Compare>
1029 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1032 return erase_at( refHead, val, cmp, [](value_type const&){}, pos );
1035 template <typename Q, typename Compare>
1036 bool extract_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& dest, Q const& val, Compare cmp )
1040 while ( search( refHead, val, pos, cmp )) {
1041 if ( unlink_node( pos )) {
1042 dest.set( pos.guards.template get<value_type>( position::guard_current_item ));
1052 template <typename Q, typename Compare>
1053 bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1056 return search( refHead, val, pos, cmp );
1059 template <typename Q, typename Compare, typename Func>
1060 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f )
1063 if ( search( refHead, val, pos, cmp )) {
1064 f( *node_traits::to_value_ptr( *pos.pCur ), val );
1070 template <typename Q, typename Compare>
1071 bool get_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp )
1074 if ( search( refHead, val, pos, cmp )) {
1075 guard.set( pos.guards.template get<value_type>( position::guard_current_item ));
1086 template <typename Q, typename Compare >
1087 bool search( atomic_node_ptr& refHead, const Q& val, position& pos, Compare cmp )
1089 atomic_node_ptr * pPrev;
1090 marked_node_ptr pNext;
1091 marked_node_ptr pCur;
1099 pCur = pos.guards.protect( position::guard_current_item, *pPrev,
1100 [](marked_node_ptr p) -> value_type *
1102 return node_traits::to_value_ptr( p.ptr());
1106 if ( pCur.ptr() == nullptr ) {
1109 pos.pNext = nullptr;
1113 pNext = pos.guards.protect( position::guard_next_item, pCur->m_pNext,
1114 [](marked_node_ptr p ) -> value_type *
1116 return node_traits::to_value_ptr( p.ptr());
1118 if ( pPrev->load(memory_model::memory_order_acquire).all() != pCur.ptr()) {
1123 // pNext contains deletion mark for pCur
1124 if ( pNext.bits() == 1 ) {
1125 // pCur marked i.e. logically deleted. Help the erase/unlink function to unlink pCur node
1126 marked_node_ptr cur( pCur.ptr());
1127 if ( pPrev->compare_exchange_strong( cur, marked_node_ptr( pNext.ptr()), memory_model::memory_order_acquire, atomics::memory_order_relaxed )) {
1128 retire_node( pCur.ptr());
1136 assert( pCur.ptr() != nullptr );
1137 int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr()), val );
1140 pos.pCur = pCur.ptr();
1141 pos.pNext = pNext.ptr();
1144 pPrev = &( pCur->m_pNext );
1145 pos.guards.copy( position::guard_prev_item, position::guard_current_item );
1148 pos.guards.copy( position::guard_current_item, position::guard_next_item );
1153 }} // namespace cds::intrusive
1155 #endif // #ifndef CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H