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_INTRUSIVE_IMPL_MICHAEL_LIST_H
32 #define CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H
34 #include <cds/intrusive/details/michael_list_base.h>
35 #include <cds/details/make_const_type.h>
37 namespace cds { namespace intrusive {
39 /// Michael's lock-free ordered single-linked list
40 /** @ingroup cds_intrusive_list
41 \anchor cds_intrusive_MichaelList_hp
43 Usually, ordered single-linked list is used as a building block for the hash table implementation.
44 The complexity of searching is <tt>O(N)</tt>.
47 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
50 - \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).
51 - \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)
52 or it must have a member of type \p michael_list::node (for \p michael_list::member_hook).
53 - \p Traits - type traits, default is \p michael_list::traits. It is possible to declare option-based
54 list with \p cds::intrusive::michael_list::make_traits metafunction:
55 For example, the following traits-based declaration of \p gc::HP Michael's list
57 #include <cds/intrusive/michael_list_hp.h>
58 // Declare item stored in your list
59 struct item: public cds::intrusive::michael_list::node< cds::gc::HP >
65 // Declare comparator for the item
67 int operator()( item const& i1, item const& i2 ) const
69 return i1.nKey - i2.nKey;
74 struct my_traits: public cds::intrusive::michael_list::traits
76 typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > hook;
77 typedef my_compare compare;
80 // Declare traits-based list
81 typedef cds::intrusive::MichaelList< cds::gc::HP, item, my_traits > traits_based_list;
83 is equivalent for the following option-based list
85 #include <cds/intrusive/michael_list_hp.h>
87 // item struct and my_compare are the same
89 // Declare option-based list
90 typedef cds::intrusive::MichaelList< cds::gc::HP, item,
91 typename cds::intrusive::michael_list::make_traits<
92 cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > > // hook option
93 ,cds::intrusive::opt::compare< my_compare > // item comparator option
99 There are different specializations of this template for each garbage collecting schema.
100 You should select GC needed and include appropriate .h-file:
101 - for \p gc::HP: <tt> <cds/intrusive/michael_list_hp.h> </tt>
102 - for \p gc::DHP: <tt> <cds/intrusive/michael_list_dhp.h> </tt>
103 - for \ref cds_urcu_gc "RCU type" - see \ref cds_intrusive_MichaelList_rcu "RCU-based MichaelList"
104 - for \p gc::nogc: <tt> <cds/intrusive/michael_list_nogc.h> </tt>
105 See \ref cds_intrusive_MichaelList_nogc "non-GC MichaelList"
107 Then, you should incorporate \p michael_list::node into your struct \p T and provide
108 appropriate \p michael_list::traits::hook in your \p Traits template parameters. Usually, for \p Traits you
109 define a struct based on \p michael_list::traits.
111 Example for \p gc::DHP and base hook:
113 // Include GC-related Michael's list specialization
114 #include <cds/intrusive/michael_list_dhp.h>
116 // Data stored in Michael's list
117 struct my_data: public cds::intrusive::michael_list::node< cds::gc::DHP >
126 // my_data comparing functor
128 int operator()( const my_data& d1, const my_data& d2 )
130 return d1.strKey.compare( d2.strKey );
133 int operator()( const my_data& d, const std::string& s )
135 return d.strKey.compare(s);
138 int operator()( const std::string& s, const my_data& d )
140 return s.compare( d.strKey );
146 struct my_traits: public cds::intrusive::michael_list::traits
148 typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::DHP > > hook;
149 typedef my_data_cmp compare;
153 typedef cds::intrusive::MichaelList< cds::gc::DHP, my_data, my_traits > traits_based_list;
156 Equivalent option-based code:
158 // GC-related specialization
159 #include <cds/intrusive/michael_list_dhp.h>
168 // Declare option-based list
169 typedef cds::intrusive::MichaelList< cds::gc::DHP
171 , typename cds::intrusive::michael_list::make_traits<
172 cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::DHP > > >
173 ,cds::intrusive::opt::compare< my_data_cmp >
182 #ifdef CDS_DOXYGEN_INVOKED
183 ,class Traits = michael_list::traits
191 typedef T value_type; ///< type of value stored in the list
192 typedef Traits traits; ///< Traits template parameter
194 typedef typename traits::hook hook; ///< hook type
195 typedef typename hook::node_type node_type; ///< node type
197 # ifdef CDS_DOXYGEN_INVOKED
198 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
200 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
203 typedef typename traits::disposer disposer; ///< disposer used
204 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
205 typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
207 typedef GC gc ; ///< Garbage collector
208 typedef typename traits::back_off back_off; ///< back-off strategy
209 typedef typename traits::item_counter item_counter; ///< Item counting policy used
210 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
212 typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
214 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = 4; ///< Count of hazard pointer required for the algorithm
217 // Rebind traits (split-list support)
218 template <typename... Options>
219 struct rebind_traits {
223 , typename cds::opt::make_options< traits, Options...>::type
229 typedef typename node_type::atomic_marked_ptr atomic_node_ptr; ///< Atomic node pointer
230 typedef typename node_type::marked_ptr marked_node_ptr; ///< Node marked pointer
232 typedef atomic_node_ptr auxiliary_head; ///< Auxiliary head type (for split-list support)
234 atomic_node_ptr m_pHead; ///< Head pointer
235 item_counter m_ItemCounter; ///< Item counter
238 /// Position pointer for item search
240 atomic_node_ptr * pPrev ; ///< Previous node
241 node_type * pCur ; ///< Current node
242 node_type * pNext ; ///< Next node
244 typename gc::template GuardArray<3> guards ; ///< Guards array
253 struct clean_disposer {
254 void operator()( value_type * p )
256 michael_list::node_cleaner<gc, node_type, memory_model>()( node_traits::to_node_ptr( p ));
264 static void retire_node( node_type * pNode )
266 assert( pNode != nullptr );
267 gc::template retire<clean_disposer>( node_traits::to_value_ptr( *pNode ));
270 static bool link_node( node_type * pNode, position& pos )
272 assert( pNode != nullptr );
273 link_checker::is_empty( pNode );
275 marked_node_ptr cur(pos.pCur);
276 pNode->m_pNext.store( cur, memory_model::memory_order_release );
277 return pos.pPrev->compare_exchange_strong( cur, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed );
280 static bool unlink_node( position& pos )
282 assert( pos.pPrev != nullptr );
283 assert( pos.pCur != nullptr );
285 // Mark the node (logical deleting)
286 marked_node_ptr next(pos.pNext, 0);
287 if ( pos.pCur->m_pNext.compare_exchange_strong( next, marked_node_ptr(pos.pNext, 1), memory_model::memory_order_release, atomics::memory_order_relaxed )) {
288 // physical deletion may be performed by search function if it detects that a node is logically deleted (marked)
289 // CAS may be successful here or in other thread that searching something
290 marked_node_ptr cur(pos.pCur);
291 if ( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr( pos.pNext ), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))
292 retire_node( pos.pCur );
301 template <bool IsConst>
304 friend class MichaelList;
307 value_type * m_pNode;
308 typename gc::Guard m_Guard;
313 typename gc::Guard g;
314 node_type * pCur = node_traits::to_node_ptr( *m_pNode );
316 marked_node_ptr pNext;
318 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed);
319 g.assign( node_traits::to_value_ptr( pNext.ptr()));
320 } while ( pNext != pCur->m_pNext.load(memory_model::memory_order_acquire));
323 m_pNode = m_Guard.assign( g.template get<value_type>());
331 iterator_type( atomic_node_ptr const& pNode )
334 marked_node_ptr p = pNode.load(memory_model::memory_order_relaxed);
336 m_pNode = m_Guard.assign( node_traits::to_value_ptr( p.ptr()));
342 if ( p == pNode.load(memory_model::memory_order_acquire))
348 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
349 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
355 iterator_type( iterator_type const& src )
358 m_pNode = m_Guard.assign( src.m_pNode );
364 value_ptr operator ->() const
369 value_ref operator *() const
371 assert( m_pNode != nullptr );
376 iterator_type& operator ++()
382 iterator_type& operator = (iterator_type const& src)
384 m_pNode = src.m_pNode;
385 m_Guard.assign( m_pNode );
391 void operator ++(int)
398 bool operator ==(iterator_type<C> const& i ) const
400 return m_pNode == i.m_pNode;
403 bool operator !=(iterator_type<C> const& i ) const
405 return m_pNode != i.m_pNode;
413 The forward iterator for Michael's list has some features:
414 - it has no post-increment operator
415 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
416 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
417 may be thrown if the limit of guard count per thread is exceeded.
418 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
419 - Iterator ensures thread-safety even if you delete the item the iterator points to. However, in case of concurrent
420 deleting operations there is no guarantee that you iterate all item in the list.
422 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
423 for debug purpose only.
425 The iterator interface:
429 // Default constructor
433 iterator( iterator const& src );
435 // Dereference operator
436 value_type * operator ->() const;
438 // Dereference operator
439 value_type& operator *() const;
441 // Preincrement operator
442 iterator& operator ++();
444 // Assignment operator
445 iterator& operator = (iterator const& src);
447 // Equality operators
448 bool operator ==(iterator const& i ) const;
449 bool operator !=(iterator const& i ) const;
453 typedef iterator_type<false> iterator;
454 /// Const forward iterator
456 For iterator's features and requirements see \ref iterator
458 typedef iterator_type<true> const_iterator;
460 /// Returns a forward iterator addressing the first element in a list
462 For empty list \code begin() == end() \endcode
466 return iterator( m_pHead );
469 /// Returns an iterator that addresses the location succeeding the last element in a list
471 Do not use the value returned by <tt>end</tt> function to access any item.
472 Internally, <tt>end</tt> returning value equals to \p nullptr.
474 The returned value can be used only to control reaching the end of the list.
475 For empty list <tt>begin() == end()</tt>
482 /// Returns a forward const iterator addressing the first element in a list
483 const_iterator cbegin() const
485 return const_iterator( m_pHead );
488 /// Returns a forward const iterator addressing the first element in a list
489 const_iterator begin() const
491 return const_iterator( m_pHead );
494 /// Returns an const iterator that addresses the location succeeding the last element in a list
495 const_iterator end() const
497 return const_iterator();
500 /// Returns an const iterator that addresses the location succeeding the last element in a list
501 const_iterator cend() const
503 return const_iterator();
507 /// Default constructor initializes empty list
511 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
514 /// Destroys the list object
522 The function inserts \p val into the list if the list does not contain
523 an item with key equal to \p val.
525 Returns \p true if \p val has been linked to the list, \p false otherwise.
527 bool insert( value_type& val )
529 return insert_at( m_pHead, val );
534 This function is intended for derived non-intrusive containers.
536 The function allows to split new item creating into two part:
537 - create item with key only
538 - insert new item into the list
539 - if inserting is success, calls \p f functor to initialize value-field of \p val.
541 The functor signature is:
543 void func( value_type& val );
545 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
546 \p val no any other changes could be made on this list's item by concurrent threads.
547 The user-defined functor is called only if the inserting is success.
549 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
551 template <typename Func>
552 bool insert( value_type& val, Func f )
554 return insert_at( m_pHead, val, f );
559 The operation performs inserting or changing data with lock-free manner.
561 If the item \p val is not found in the list, then \p val is inserted
562 iff \p bInsert is \p true.
563 Otherwise, the functor \p func is called with item found.
564 The functor signature is:
566 void func( bool bNew, value_type& item, value_type& val );
569 - \p bNew - \p true if the item has been inserted, \p false otherwise
570 - \p item - item of the list
571 - \p val - argument \p val passed into the \p update() function
572 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
573 refers to the same thing.
575 The functor may change non-key fields of the \p item; however, \p func must guarantee
576 that during changing no any other modifications could be made on this item by concurrent threads.
578 Returns std::pair<bool, bool> where \p first is \p true if operation is successfull,
579 \p second is \p true if new item has been added or \p false if the item with \p key
580 already is in the list.
582 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
584 template <typename Func>
585 std::pair<bool, bool> update( value_type& val, Func func, bool bInsert = true )
587 return update_at( m_pHead, val, func, bInsert );
591 template <typename Func>
592 CDS_DEPRECATED("ensure() is deprecated, use update()")
593 std::pair<bool, bool> ensure( value_type& val, Func func )
595 return update( val, func, true );
599 /// Unlinks the item \p val from the list
601 The function searches the item \p val in the list and unlinks it from the list
602 if it is found and it is equal to \p val.
604 Difference between \p erase() and \p %unlink(): \p %erase() finds <i>a key</i>
605 and deletes the item found. \p %unlink() finds an item by key and deletes it
606 only if \p val is an item of the list, i.e. the pointer to item found
607 is equal to <tt> &val </tt>.
609 \p disposer specified in \p Traits is called for deleted item.
611 The function returns \p true if success and \p false otherwise.
613 bool unlink( value_type& val )
615 return unlink_at( m_pHead, val );
618 /// Deletes the item from the list
619 /** \anchor cds_intrusive_MichaelList_hp_erase_val
620 The function searches an item with key equal to \p key in the list,
621 unlinks it from the list, and returns \p true.
622 If \p key is not found the function return \p false.
624 \p disposer specified in \p Traits is called for deleted item.
626 template <typename Q>
627 bool erase( Q const& key )
629 return erase_at( m_pHead, key, key_comparator());
632 /// Deletes the item from the list using \p pred predicate for searching
634 The function is an analog of \ref cds_intrusive_MichaelList_hp_erase_val "erase(Q const&)"
635 but \p pred is used for key comparing.
636 \p Less functor has the interface like \p std::less.
637 \p pred must imply the same element order as the comparator used for building the list.
639 \p disposer specified in \p Traits is called for deleted item.
641 template <typename Q, typename Less>
642 bool erase_with( Q const& key, Less pred )
645 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
648 /// Deletes the item from the list
649 /** \anchor cds_intrusive_MichaelList_hp_erase_func
650 The function searches an item with key equal to \p key in the list,
651 call \p func functor with item found, unlinks it from the list, and returns \p true.
652 The \p Func interface is
655 void operator()( value_type const& item );
658 If \p key is not found the function return \p false, \p func is not called.
660 \p disposer specified in \p Traits is called for deleted item.
662 template <typename Q, typename Func>
663 bool erase( Q const& key, Func func )
665 return erase_at( m_pHead, key, key_comparator(), func );
668 /// Deletes the item from the list using \p pred predicate for searching
670 The function is an analog of \ref cds_intrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
671 but \p pred is used for key comparing.
672 \p Less functor has the interface like \p std::less.
673 \p pred must imply the same element order as the comparator used for building the list.
675 \p disposer specified in \p Traits is called for deleted item.
677 template <typename Q, typename Less, typename Func>
678 bool erase_with( Q const& key, Less pred, Func f )
681 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
684 /// Extracts the item from the list with specified \p key
685 /** \anchor cds_intrusive_MichaelList_hp_extract
686 The function searches an item with key equal to \p key,
687 unlinks it from the list, and returns it as \p guarded_ptr.
688 If \p key is not found returns an empty guarded pointer.
690 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
692 The \ref disposer specified in \p Traits class template parameter is called automatically
693 by garbage collector \p GC when returned \ref guarded_ptr object will be destroyed or released.
694 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
698 typedef cds::intrusive::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
702 ord_list::guarded_ptr gp(theList.extract( 5 ));
707 // Destructor of gp releases internal HP guard
711 template <typename Q>
712 guarded_ptr extract( Q const& key )
715 extract_at( m_pHead, gp.guard(), key, key_comparator());
719 /// Extracts the item using compare functor \p pred
721 The function is an analog of \ref cds_intrusive_MichaelList_hp_extract "extract(Q const&)"
722 but \p pred predicate is used for key comparing.
724 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
726 \p pred must imply the same element order as the comparator used for building the list.
728 template <typename Q, typename Less>
729 guarded_ptr extract_with( Q const& key, Less pred )
733 extract_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
737 /// Finds \p key in the list
738 /** \anchor cds_intrusive_MichaelList_hp_find_func
739 The function searches the item with key equal to \p key and calls the functor \p f for item found.
740 The interface of \p Func functor is:
743 void operator()( value_type& item, Q& key );
746 where \p item is the item found, \p key is the <tt>find</tt> function argument.
748 The functor may change non-key fields of \p item. Note that the function is only guarantee
749 that \p item cannot be disposed during functor is executing.
750 The function does not serialize simultaneous access to the \p item. If such access is
751 possible you must provide your own synchronization schema to keep out unsafe item modifications.
753 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
754 may modify both arguments.
756 The function returns \p true if \p val is found, \p false otherwise.
758 template <typename Q, typename Func>
759 bool find( Q& key, Func f )
761 return find_at( m_pHead, key, key_comparator(), f );
764 template <typename Q, typename Func>
765 bool find( Q const& key, Func f )
767 return find_at( m_pHead, key, key_comparator(), f );
771 /// Finds the \p key using \p pred predicate for searching
773 The function is an analog of \ref cds_intrusive_MichaelList_hp_find_func "find(Q&, Func)"
774 but \p pred is used for key comparing.
775 \p Less functor has the interface like \p std::less.
776 \p pred must imply the same element order as the comparator used for building the list.
778 template <typename Q, typename Less, typename Func>
779 bool find_with( Q& key, Less pred, Func f )
782 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
785 template <typename Q, typename Less, typename Func>
786 bool find_with( Q const& key, Less pred, Func f )
789 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
793 /// Checks whether the list contains \p key
795 The function searches the item with key equal to \p key
796 and returns \p true if it is found, and \p false otherwise.
798 template <typename Q>
799 bool contains( Q const& key )
801 return find_at( m_pHead, key, key_comparator());
804 template <typename Q>
805 CDS_DEPRECATED("deprecated, use contains()")
806 bool find( Q const& key )
808 return contains( key );
812 /// Checks whether the list contains \p key using \p pred predicate for searching
814 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
815 \p Less functor has the interface like \p std::less.
816 \p Less must imply the same element order as the comparator used for building the list.
818 template <typename Q, typename Less>
819 bool contains( Q const& key, Less pred )
822 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
825 template <typename Q, typename Less>
826 CDS_DEPRECATED("deprecated, use contains()")
827 bool find_with( Q const& key, Less pred )
829 return contains( key, pred );
833 /// Finds the \p key and return the item found
834 /** \anchor cds_intrusive_MichaelList_hp_get
835 The function searches the item with key equal to \p key
836 and returns it as \p guarded_ptr.
837 If \p key is not found the function returns an empty guarded pointer.
839 The \ref disposer specified in \p Traits class template parameter is called
840 by garbage collector \p GC automatically when returned \ref guarded_ptr object
841 will be destroyed or released.
842 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
846 typedef cds::intrusive::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
850 ord_list::guarded_ptr gp(theList.get( 5 ));
855 // Destructor of guarded_ptr releases internal HP guard
859 Note the compare functor specified for \p Traits template parameter
860 should accept a parameter of type \p Q that can be not the same as \p value_type.
862 template <typename Q>
863 guarded_ptr get( Q const& key )
866 get_at( m_pHead, gp.guard(), key, key_comparator());
870 /// Finds the \p key and return the item found
872 The function is an analog of \ref cds_intrusive_MichaelList_hp_get "get( Q const&)"
873 but \p pred is used for comparing the keys.
875 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
877 \p pred must imply the same element order as the comparator used for building the list.
879 template <typename Q, typename Less>
880 guarded_ptr get_with( Q const& key, Less pred )
884 get_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
890 The function unlink all items from the list.
894 typename gc::Guard guard;
895 marked_node_ptr head;
897 head = m_pHead.load(memory_model::memory_order_relaxed);
899 guard.assign( node_traits::to_value_ptr( *head.ptr()));
900 if ( m_pHead.load(memory_model::memory_order_acquire) == head ) {
901 if ( head.ptr() == nullptr )
903 value_type& val = *node_traits::to_value_ptr( *head.ptr());
909 /// Checks whether the list is empty
912 return m_pHead.load( memory_model::memory_order_relaxed ).all() == nullptr;
915 /// Returns list's item count
917 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
918 this function always returns 0.
920 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
921 is empty. To check list emptyness use \p empty() method.
925 return m_ItemCounter.value();
930 // split-list support
931 bool insert_aux_node( node_type * pNode )
933 return insert_aux_node( m_pHead, pNode );
936 // split-list support
937 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
939 assert( pNode != nullptr );
941 // Hack: convert node_type to value_type.
942 // In principle, auxiliary node can be non-reducible to value_type
943 // We assume that comparator can correctly distinguish aux and regular node.
944 return insert_at( refHead, *node_traits::to_value_ptr( pNode ));
947 bool insert_at( atomic_node_ptr& refHead, value_type& val )
949 node_type * pNode = node_traits::to_node_ptr( val );
953 if ( search( refHead, val, pos, key_comparator()))
956 if ( link_node( pNode, pos )) {
962 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
966 template <typename Func>
967 bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
969 node_type * pNode = node_traits::to_node_ptr( val );
973 if ( search( refHead, val, pos, key_comparator()))
976 typename gc::Guard guard;
977 guard.assign( &val );
978 if ( link_node( pNode, pos )) {
985 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
989 template <typename Func>
990 std::pair<bool, bool> update_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bInsert )
994 node_type * pNode = node_traits::to_node_ptr( val );
996 if ( search( refHead, val, pos, key_comparator())) {
997 if ( pos.pCur->m_pNext.load(memory_model::memory_order_acquire).bits()) {
999 continue; // the node found is marked as deleted
1001 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur )) == 0 );
1003 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
1004 return std::make_pair( true, false );
1008 return std::make_pair( false, false );
1010 typename gc::Guard guard;
1011 guard.assign( &val );
1012 if ( link_node( pNode, pos )) {
1014 func( true, val, val );
1015 return std::make_pair( true, true );
1018 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
1023 bool unlink_at( atomic_node_ptr& refHead, value_type& val )
1028 while ( search( refHead, val, pos, key_comparator())) {
1029 if ( node_traits::to_value_ptr( *pos.pCur ) == &val ) {
1030 if ( unlink_node( pos )) {
1043 template <typename Q, typename Compare, typename Func>
1044 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f, position& pos )
1047 while ( search( refHead, val, pos, cmp )) {
1048 if ( unlink_node( pos )) {
1049 f( *node_traits::to_value_ptr( *pos.pCur ));
1059 template <typename Q, typename Compare, typename Func>
1060 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f )
1063 return erase_at( refHead, val, cmp, f, pos );
1066 template <typename Q, typename Compare>
1067 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1070 return erase_at( refHead, val, cmp, [](value_type const&){}, pos );
1073 template <typename Q, typename Compare>
1074 bool extract_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& dest, Q const& val, Compare cmp )
1078 while ( search( refHead, val, pos, cmp )) {
1079 if ( unlink_node( pos )) {
1080 dest.set( pos.guards.template get<value_type>( position::guard_current_item ));
1090 template <typename Q, typename Compare>
1091 bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1094 return search( refHead, val, pos, cmp );
1097 template <typename Q, typename Compare, typename Func>
1098 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f )
1101 if ( search( refHead, val, pos, cmp )) {
1102 f( *node_traits::to_value_ptr( *pos.pCur ), val );
1108 template <typename Q, typename Compare>
1109 bool get_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp )
1112 if ( search( refHead, val, pos, cmp )) {
1113 guard.set( pos.guards.template get<value_type>( position::guard_current_item ));
1124 template <typename Q, typename Compare >
1125 bool search( atomic_node_ptr& refHead, const Q& val, position& pos, Compare cmp )
1127 atomic_node_ptr * pPrev;
1128 marked_node_ptr pNext;
1129 marked_node_ptr pCur;
1137 pCur = pos.guards.protect( position::guard_current_item, *pPrev,
1138 [](marked_node_ptr p) -> value_type *
1140 return node_traits::to_value_ptr( p.ptr());
1144 if ( pCur.ptr() == nullptr ) {
1147 pos.pNext = nullptr;
1151 pNext = pos.guards.protect( position::guard_next_item, pCur->m_pNext,
1152 [](marked_node_ptr p ) -> value_type *
1154 return node_traits::to_value_ptr( p.ptr());
1156 if ( pPrev->load(memory_model::memory_order_acquire).all() != pCur.ptr()) {
1161 // pNext contains deletion mark for pCur
1162 if ( pNext.bits() == 1 ) {
1163 // pCur marked i.e. logically deleted. Help the erase/unlink function to unlink pCur node
1164 marked_node_ptr cur( pCur.ptr());
1165 if ( pPrev->compare_exchange_strong( cur, marked_node_ptr( pNext.ptr()), memory_model::memory_order_acquire, atomics::memory_order_relaxed )) {
1166 retire_node( pCur.ptr());
1174 assert( pCur.ptr() != nullptr );
1175 int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr()), val );
1178 pos.pCur = pCur.ptr();
1179 pos.pNext = pNext.ptr();
1182 pPrev = &( pCur->m_pNext );
1183 pos.guards.copy( position::guard_prev_item, position::guard_current_item );
1186 pos.guards.copy( position::guard_current_item, position::guard_next_item );
1191 }} // namespace cds::intrusive
1193 #endif // #ifndef CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H