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_LAZY_LIST_H
32 #define CDSLIB_INTRUSIVE_IMPL_LAZY_LIST_H
34 #include <mutex> // unique_lock
35 #include <cds/intrusive/details/lazy_list_base.h>
37 namespace cds { namespace intrusive {
39 /// Lazy ordered single-linked list
40 /** @ingroup cds_intrusive_list
41 \anchor cds_intrusive_LazyList_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 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
48 "A Lazy Concurrent List-Based Set Algorithm"
50 The lazy list is based on an optimistic locking scheme for inserts and removes,
51 eliminating the need to use the equivalent of an atomically markable
52 reference. It also has a novel wait-free membership \p find operation
53 that does not need to perform cleanup operations and is more efficient.
56 - \p GC - Garbage collector used. Note the \p GC must be the same as the GC used for item type \p T (see lazy_list::node).
57 - \p T - type to be stored in the list. The type must be based on lazy_list::node (for lazy_list::base_hook)
58 or it must have a member of type lazy_list::node (for lazy_list::member_hook).
59 - \p Traits - type traits. See lazy_list::traits for explanation.
60 It is possible to declare option-based list with cds::intrusive::lazy_list::make_traits metafunction istead of \p Traits template
61 argument. For example, the following traits-based declaration of \p gc::HP lazy list
63 #include <cds/intrusive/lazy_list_hp.h>
64 // Declare item stored in your list
65 struct item: public cds::intrusive::lazy_list::node< cds::gc::HP >
68 // Declare comparator for the item
69 struct my_compare { ... }
72 struct my_traits: public cds::intrusive::lazy_list::traits
74 typedef cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::HP > > hook;
75 typedef my_compare compare;
78 // Declare traits-based list
79 typedef cds::intrusive::LazyList< cds::gc::HP, item, my_traits > traits_based_list;
81 is equivalent for the following option-based list
83 #include <cds/intrusive/lazy_list_hp.h>
85 // item struct and my_compare are the same
87 // Declare option-based list
88 typedef cds::intrusive::LazyList< cds::gc::HP, item,
89 typename cds::intrusive::lazy_list::make_traits<
90 cds::intrusive::opt::hook< cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::HP > > > // hook option
91 ,cds::intrusive::opt::compare< my_compare > // item comparator option
97 There are different specializations of this template for each garbage collecting schema used.
98 You should select GC needed and include appropriate .h-file:
99 - for gc::HP: \code #include <cds/intrusive/lazy_list_hp.h> \endcode
100 - for gc::DHP: \code #include <cds/intrusive/lazy_list_dhp.h> \endcode
101 - for gc::nogc: \code #include <cds/intrusive/lazy_list_nogc.h> \endcode
102 - for \ref cds_urcu_type "RCU" - see \ref cds_intrusive_LazyList_rcu "LazyList RCU specialization"
104 Then, you should incorporate lazy_list::node into your struct \p T and provide
105 appropriate \p lazy_list::traits::hook in your \p Traits template parameters. Usually, for \p Traits
106 a struct based on \p lazy_list::traits should be defined.
108 Example for gc::DHP and base hook:
110 // Include GC-related lazy list specialization
111 #include <cds/intrusive/lazy_list_dhp.h>
113 // Data stored in lazy list
114 struct my_data: public cds::intrusive::lazy_list::node< cds::gc::DHP >
123 // my_data comparing functor
125 int operator()( const my_data& d1, const my_data& d2 )
127 return d1.strKey.compare( d2.strKey );
130 int operator()( const my_data& d, const std::string& s )
132 return d.strKey.compare(s);
135 int operator()( const std::string& s, const my_data& d )
137 return s.compare( d.strKey );
142 struct my_traits: public cds::intrusive::lazy_list::traits
144 typedef cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::DHP > > hook;
145 typedef my_data_cmp compare;
149 typedef cds::intrusive::LazyList< cds::gc::DHP, my_data, my_traits > traits_based_list;
152 Equivalent option-based code:
154 // GC-related specialization
155 #include <cds/intrusive/lazy_list_dhp.h>
164 // Declare option-based list
165 typedef cds::intrusive::LazyList< cds::gc::DHP
167 , typename cds::intrusive::lazy_list::make_traits<
168 cds::intrusive::opt::hook< cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::DHP > > >
169 ,cds::intrusive::opt::compare< my_data_cmp >
178 #ifdef CDS_DOXYGEN_INVOKED
179 ,class Traits = lazy_list::traits
187 typedef GC gc; ///< Garbage collector
188 typedef T value_type; ///< type of value stored in the list
189 typedef Traits traits; ///< Traits template parameter
191 typedef typename traits::hook hook; ///< hook type
192 typedef typename hook::node_type node_type; ///< node type
194 # ifdef CDS_DOXYGEN_INVOKED
195 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
197 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
200 typedef typename traits::disposer disposer; ///< disposer
201 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits; ///< node traits
202 typedef typename lazy_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
204 typedef typename traits::back_off back_off ; ///< back-off strategy
205 typedef typename traits::item_counter item_counter ; ///< Item counting policy used
206 typedef typename traits::memory_model memory_model; ///< C++ memory ordering (see \p lazy_list::traits::memory_model)
208 typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
210 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = 4; ///< Count of hazard pointer required for the algorithm
213 // Rebind traits (split-list support)
214 template <typename... Options>
215 struct rebind_traits {
219 , typename cds::opt::make_options< traits, Options...>::type
225 typedef typename node_type::marked_ptr marked_node_ptr; ///< Node marked pointer
226 typedef node_type * auxiliary_head; ///< Auxiliary head type (for split-list support)
233 item_counter m_ItemCounter ; ///< Item counter
236 struct clean_disposer {
237 void operator()( value_type * p )
239 lazy_list::node_cleaner<gc, node_type, memory_model>()( node_traits::to_node_ptr( p ));
244 /// Position pointer for item search
246 node_type * pPred ; ///< Previous node
247 node_type * pCur ; ///< Current node
249 typename gc::template GuardArray<2> guards ; ///< Guards array
256 /// Locks nodes \p pPred and \p pCur
259 pPred->m_Lock.lock();
263 /// Unlocks nodes \p pPred and \p pCur
266 pCur->m_Lock.unlock();
267 pPred->m_Lock.unlock();
271 typedef std::unique_lock< position > scoped_position_lock;
276 void link_node( node_type * pNode, node_type * pPred, node_type * pCur )
278 assert( pPred->m_pNext.load(memory_model::memory_order_relaxed).ptr() == pCur );
279 link_checker::is_empty( pNode );
281 pNode->m_pNext.store( marked_node_ptr(pCur), memory_model::memory_order_release );
282 pPred->m_pNext.store( marked_node_ptr(pNode), memory_model::memory_order_release );
285 void unlink_node( node_type * pPred, node_type * pCur, node_type * pHead )
287 assert( pPred->m_pNext.load(memory_model::memory_order_relaxed).ptr() == pCur );
289 node_type * pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr();
290 pCur->m_pNext.store( marked_node_ptr( pHead, 1 ), memory_model::memory_order_release ); // logical removal + back-link for search
291 pPred->m_pNext.store( marked_node_ptr( pNext ), memory_model::memory_order_release); // physically deleting
294 void retire_node( node_type * pNode )
296 assert( pNode != nullptr );
297 gc::template retire<clean_disposer>( node_traits::to_value_ptr( *pNode ));
303 template <bool IsConst>
306 friend class LazyList;
309 value_type * m_pNode;
310 typename gc::Guard m_Guard;
314 assert( m_pNode != nullptr );
317 typename gc::Guard g;
318 node_type * pCur = node_traits::to_node_ptr( m_pNode );
319 if ( pCur->m_pNext.load( memory_model::memory_order_relaxed ).ptr() != nullptr ) { // if pCur is not tail node
322 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr();
323 g.assign( node_traits::to_value_ptr( pNext ));
324 } while ( pNext != pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr());
326 m_pNode = m_Guard.assign( g.template get<value_type>());
333 if ( m_pNode != nullptr ) {
334 typename gc::Guard g;
335 node_type * pNode = node_traits::to_node_ptr( m_pNode );
337 // Dummy tail node could not be marked
338 while ( pNode->is_marked()) {
339 node_type * p = pNode->m_pNext.load(memory_model::memory_order_relaxed).ptr();
340 g.assign( node_traits::to_value_ptr( p ));
341 if ( p == pNode->m_pNext.load(memory_model::memory_order_relaxed).ptr())
344 if ( pNode != node_traits::to_node_ptr( m_pNode ))
345 m_pNode = m_Guard.assign( g.template get<value_type>());
349 iterator_type( node_type * pNode )
351 m_pNode = m_Guard.assign( node_traits::to_value_ptr( pNode ));
356 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
357 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
363 iterator_type( iterator_type const& src )
366 m_pNode = m_Guard.assign( src.m_pNode );
372 value_ptr operator ->() const
377 value_ref operator *() const
379 assert( m_pNode != nullptr );
384 iterator_type& operator ++()
391 iterator_type& operator = (iterator_type const& src)
393 m_pNode = src.m_pNode;
394 m_Guard.assign( m_pNode );
399 bool operator ==(iterator_type<C> const& i ) const
401 return m_pNode == i.m_pNode;
404 bool operator !=(iterator_type<C> const& i ) const
406 return m_pNode != i.m_pNode;
414 The forward iterator for lazy list has some features:
415 - it has no post-increment operator
416 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
417 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
418 may be thrown if a limit of guard count per thread is exceeded.
419 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
420 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
421 deleting operations it is no guarantee that you iterate all item in the list.
423 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
424 for debug purpose only.
426 typedef iterator_type<false> iterator;
427 /// Const forward iterator
429 For iterator's features and requirements see \ref iterator
431 typedef iterator_type<true> const_iterator;
433 /// Returns a forward iterator addressing the first element in a list
435 For empty list \code begin() == end() \endcode
439 iterator it( &m_Head );
440 ++it ; // skip dummy head
444 /// Returns an iterator that addresses the location succeeding the last element in a list
446 Do not use the value returned by <tt>end</tt> function to access any item.
448 The returned value can be used only to control reaching the end of the list.
449 For empty list \code begin() == end() \endcode
453 return iterator( &m_Tail );
456 /// Returns a forward const iterator addressing the first element in a list
458 const_iterator begin() const
460 return get_const_begin();
462 const_iterator cbegin() const
464 return get_const_begin();
468 /// Returns an const iterator that addresses the location succeeding the last element in a list
470 const_iterator end() const
472 return get_const_end();
474 const_iterator cend() const
476 return get_const_end();
482 const_iterator get_const_begin() const
484 const_iterator it( const_cast<node_type *>( &m_Head ));
485 ++it ; // skip dummy head
488 const_iterator get_const_end() const
490 return const_iterator( const_cast<node_type *>(&m_Tail));
495 /// Default constructor initializes empty list
498 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
499 m_Head.m_pNext.store( marked_node_ptr( &m_Tail ), memory_model::memory_order_relaxed );
502 /// Destroys the list object
506 assert( m_Head.m_pNext.load( memory_model::memory_order_relaxed ).ptr() == &m_Tail );
507 m_Head.m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
512 The function inserts \p val in the list if the list does not contain
513 an item with key equal to \p val.
515 Returns \p true if \p val is linked into the list, \p false otherwise.
517 bool insert( value_type& val )
519 return insert_at( &m_Head, val );
524 This function is intended for derived non-intrusive containers.
526 The function allows to split new item creating into two part:
527 - create item with key only
528 - insert new item into the list
529 - if inserting is success, calls \p f functor to initialize value-field of \p val.
531 The functor signature is:
533 void func( value_type& val );
535 where \p val is the item inserted.
536 While the functor \p f is called the item \p val is locked so
537 the functor has an exclusive access to the item.
538 The user-defined functor is called only if the inserting is success.
540 template <typename Func>
541 bool insert( value_type& val, Func f )
543 return insert_at( &m_Head, val, f );
548 The operation performs inserting or changing data with lock-free manner.
550 If the item \p val not found in the list, then \p val is inserted into the list
551 iff \p bAllowInsert is \p true.
552 Otherwise, the functor \p func is called with item found.
553 The functor signature is:
556 void operator()( bool bNew, value_type& item, value_type& val );
560 - \p bNew - \p true if the item has been inserted, \p false otherwise
561 - \p item - item of the list
562 - \p val - argument \p val passed into the \p update() function
563 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
564 refer to the same thing.
566 The functor may change non-key fields of the \p item.
567 While the functor \p f is working the item \p item is locked,
568 so \p func has exclusive access to the item.
570 Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successfull,
571 \p second is \p true if new item has been added or \p false if the item with \p key
572 already is in the list.
574 The function makes RCU lock internally.
576 template <typename Func>
577 std::pair<bool, bool> update( value_type& val, Func func, bool bAllowInsert = true )
579 return update_at( &m_Head, val, func, bAllowInsert );
582 template <typename Func>
583 CDS_DEPRECATED("ensure() is deprecated, use update()")
584 std::pair<bool, bool> ensure( value_type& val, Func func )
586 return update( val, func, true );
590 /// Unlinks the item \p val from the list
592 The function searches the item \p val in the list and unlink it from the list
593 if it is found and it is equal to \p val.
595 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
596 and deletes the item found. \p unlink finds an item by key and deletes it
597 only if \p val is an item of that list, i.e. the pointer to item found
598 is equal to <tt> &val </tt>.
600 The function returns \p true if success and \p false otherwise.
602 \p disposer specified in \p Traits is called for unlinked item.
604 bool unlink( value_type& val )
606 return unlink_at( &m_Head, val );
609 /// Deletes the item from the list
610 /** \anchor cds_intrusive_LazyList_hp_erase_val
611 The function searches an item with key equal to \p key in the list,
612 unlinks it from the list, and returns \p true.
613 If the item with the key equal to \p key is not found the function return \p false.
615 \p disposer specified in \p Traits is called for deleted item.
617 template <typename Q>
618 bool erase( Q const& key )
620 return erase_at( &m_Head, key, key_comparator());
623 /// Deletes the item from the list using \p pred predicate for searching
625 The function is an analog of \ref cds_intrusive_LazyList_hp_erase_val "erase(Q const&)"
626 but \p pred is used for key comparing.
627 \p Less functor has the interface like \p std::less.
628 \p pred must imply the same element order as the comparator used for building the list.
630 \p disposer specified in \p Traits is called for deleted item.
632 template <typename Q, typename Less>
633 bool erase_with( Q const& key, Less pred )
636 return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
639 /// Deletes the item from the list
640 /** \anchor cds_intrusive_LazyList_hp_erase_func
641 The function searches an item with key equal to \p key in the list,
642 call \p func functor with item found, unlinks it from the list, and returns \p true.
643 The \p Func interface is
646 void operator()( value_type const& item );
650 If \p key is not found the function return \p false.
652 \p disposer specified in \p Traits is called for deleted item.
654 template <typename Q, typename Func>
655 bool erase( const Q& key, Func func )
657 return erase_at( &m_Head, key, key_comparator(), func );
660 /// Deletes the item from the list using \p pred predicate for searching
662 The function is an analog of \ref cds_intrusive_LazyList_hp_erase_func "erase(Q const&, Func)"
663 but \p pred is used for key comparing.
664 \p Less functor has the interface like \p std::less.
665 \p pred must imply the same element order as the comparator used for building the list.
667 \p disposer specified in \p Traits is called for deleted item.
669 template <typename Q, typename Less, typename Func>
670 bool erase_with( const Q& key, Less pred, Func func )
673 return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), func );
676 /// Extracts the item from the list with specified \p key
677 /** \anchor cds_intrusive_LazyList_hp_extract
678 The function searches an item with key equal to \p key,
679 unlinks it from the list, and returns it as \p guarded_ptr.
680 If \p key is not found the function returns an empty guarded pointer.
682 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
684 The \ref disposer specified in \p Traits class template parameter is called automatically
685 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
686 will be destroyed or released.
687 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
691 typedef cds::intrusive::LazyList< cds::gc::HP, foo, my_traits > ord_list;
695 ord_list::guarded_ptr gp( theList.extract( 5 ));
699 // Destructor of gp releases internal HP guard
703 template <typename Q>
704 guarded_ptr extract( Q const& key )
707 extract_at( &m_Head, gp.guard(), key, key_comparator());
711 /// Extracts the item from the list with comparing functor \p pred
713 The function is an analog of \ref cds_intrusive_LazyList_hp_extract "extract(Q const&)"
714 but \p pred predicate is used for key comparing.
716 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
718 \p pred must imply the same element order as the comparator used for building the list.
720 template <typename Q, typename Less>
721 guarded_ptr extract_with( Q const& key, Less pred )
725 extract_at( &m_Head, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
729 /// Finds the key \p key
730 /** \anchor cds_intrusive_LazyList_hp_find
731 The function searches the item with key equal to \p key and calls the functor \p f for item found.
732 The interface of \p Func functor is:
735 void operator()( value_type& item, Q& key );
738 where \p item is the item found, \p key is the <tt>find</tt> function argument.
740 The functor may change non-key fields of \p item.
741 While the functor \p f is calling the item \p item is locked.
743 The function returns \p true if \p key is found, \p false otherwise.
745 template <typename Q, typename Func>
746 bool find( Q& key, Func f )
748 return find_at( &m_Head, key, key_comparator(), f );
751 template <typename Q, typename Func>
752 bool find( Q const& key, Func f )
754 return find_at( &m_Head, key, key_comparator(), f );
758 /// Finds the key \p key using \p pred predicate for searching
760 The function is an analog of \ref cds_intrusive_LazyList_hp_find "find(Q&, Func)"
761 but \p pred is used for key comparing.
762 \p Less functor has the interface like \p std::less.
763 \p pred must imply the same element order as the comparator used for building the list.
765 template <typename Q, typename Less, typename Func>
766 bool find_with( Q& key, Less pred, Func f )
769 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
772 template <typename Q, typename Less, typename Func>
773 bool find_with( Q const& key, Less pred, Func f )
776 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
780 /// Checks whether the list contains \p key
782 The function searches the item with key equal to \p key
783 and returns \p true if it is found, and \p false otherwise.
785 template <typename Q>
786 bool contains( Q const& key )
788 return find_at( &m_Head, key, key_comparator());
791 template <typename Q>
792 CDS_DEPRECATED("deprecated, use contains()")
793 bool find( Q const& key )
795 return contains( key );
799 /// Checks whether the map contains \p key using \p pred predicate for searching
801 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
802 \p Less functor has the interface like \p std::less.
803 \p Less must imply the same element order as the comparator used for building the list.
805 template <typename Q, typename Less>
806 bool contains( Q const& key, Less pred )
809 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
812 template <typename Q, typename Less>
813 CDS_DEPRECATED("deprecated, use contains()")
814 bool find_with( Q const& key, Less pred )
816 return contains( key, pred );
820 /// Finds \p key and return the item found
821 /** \anchor cds_intrusive_LazyList_hp_get
822 The function searches the item with key equal to \p key
823 and returns an guarded pointer to it.
824 If \p key is not found the function returns an empty guarded pointer.
826 The \ref disposer specified in \p Traits class template parameter is called
827 by garbage collector \p GC automatically when returned \p guarded_ptr object
828 will be destroyed or released.
829 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
833 typedef cds::intrusive::LazyList< cds::gc::HP, foo, my_traits > ord_list;
837 ord_list::guarded_ptr gp(theList.get( 5 ));
842 // Destructor of guarded_ptr releases internal HP guard
846 Note the compare functor specified for class \p Traits template parameter
847 should accept a parameter of type \p Q that can be not the same as \p value_type.
849 template <typename Q>
850 guarded_ptr get( Q const& key )
853 get_at( &m_Head, gp.guard(), key, key_comparator());
857 /// Finds \p key and return the item found
859 The function is an analog of \ref cds_intrusive_LazyList_hp_get "get( Q const&)"
860 but \p pred is used for comparing the keys.
862 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
864 \p pred must imply the same element order as the comparator used for building the list.
866 template <typename Q, typename Less>
867 guarded_ptr get_with( Q const& key, Less pred )
871 get_at( &m_Head, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
878 typename gc::Guard guard;
881 h = m_Head.m_pNext.load( memory_model::memory_order_relaxed );
882 guard.assign( node_traits::to_value_ptr( h.ptr()));
883 if ( m_Head.m_pNext.load(memory_model::memory_order_acquire) == h ) {
884 m_Head.m_Lock.lock();
887 unlink_node( &m_Head, h.ptr(), &m_Head );
891 m_Head.m_Lock.unlock();
893 retire_node( h.ptr()) ; // free node
898 /// Checks if the list is empty
901 return m_Head.m_pNext.load( memory_model::memory_order_relaxed ).ptr() == &m_Tail;
904 /// Returns list's item count
906 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
907 this function always returns 0.
909 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
910 is empty. To check list emptyness use \p empty() method.
914 return m_ItemCounter.value();
919 // split-list support
920 bool insert_aux_node( node_type * pNode )
922 return insert_aux_node( &m_Head, pNode );
925 // split-list support
926 bool insert_aux_node( node_type * pHead, node_type * pNode )
928 assert( pNode != nullptr );
930 // Hack: convert node_type to value_type.
931 // In principle, auxiliary node cannot be reducible to value_type
932 // We assume that internal comparator can correctly distinguish aux and regular node.
933 return insert_at( pHead, *node_traits::to_value_ptr( pNode ));
936 bool insert_at( node_type * pHead, value_type& val )
942 search( pHead, val, pos, key_comparator());
944 scoped_position_lock alp( pos );
945 if ( validate( pos.pPred, pos.pCur )) {
946 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
947 // failed: key already in list
951 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
960 template <typename Func>
961 bool insert_at( node_type * pHead, value_type& val, Func f )
967 search( pHead, val, pos, key_comparator());
969 scoped_position_lock alp( pos );
970 if ( validate( pos.pPred, pos.pCur )) {
971 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
972 // failed: key already in list
976 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
986 template <typename Func>
987 std::pair<bool, bool> update_at( node_type * pHead, value_type& val, Func func, bool bAllowInsert )
993 search( pHead, val, pos, key_comparator());
995 scoped_position_lock alp( pos );
996 if ( validate( pos.pPred, pos.pCur )) {
997 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
998 // key already in the list
1000 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
1001 return std::make_pair( true, false );
1005 if ( !bAllowInsert )
1006 return std::make_pair( false, false );
1008 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
1009 func( true, val, val );
1011 return std::make_pair( true, true );
1018 bool unlink_at( node_type * pHead, value_type& val )
1024 search( pHead, val, pos, key_comparator());
1028 scoped_position_lock alp( pos );
1029 if ( validate( pos.pPred, pos.pCur )) {
1030 if ( pos.pCur != &m_Tail
1031 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0
1032 && node_traits::to_value_ptr( pos.pCur ) == &val )
1035 unlink_node( pos.pPred, pos.pCur, pHead );
1044 if ( nResult > 0 ) {
1045 retire_node( pos.pCur );
1054 template <typename Q, typename Compare, typename Func>
1055 bool erase_at( node_type * pHead, const Q& val, Compare cmp, Func f, position& pos )
1058 search( pHead, val, pos, cmp );
1062 scoped_position_lock alp( pos );
1063 if ( validate( pos.pPred, pos.pCur )) {
1064 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
1066 unlink_node( pos.pPred, pos.pCur, pHead );
1067 f( *node_traits::to_value_ptr( *pos.pCur ));
1077 if ( nResult > 0 ) {
1078 retire_node( pos.pCur );
1087 template <typename Q, typename Compare, typename Func>
1088 bool erase_at( node_type * pHead, const Q& val, Compare cmp, Func f )
1091 return erase_at( pHead, val, cmp, f, pos );
1094 template <typename Q, typename Compare>
1095 bool erase_at( node_type * pHead, const Q& val, Compare cmp )
1098 return erase_at( pHead, val, cmp, [](value_type const &){}, pos );
1101 template <typename Q, typename Compare>
1102 bool extract_at( node_type * pHead, typename guarded_ptr::native_guard& gp, const Q& val, Compare cmp )
1105 if ( erase_at( pHead, val, cmp, [](value_type const &){}, pos )) {
1106 gp.set( pos.guards.template get<value_type>(position::guard_current_item));
1112 template <typename Q, typename Compare, typename Func>
1113 bool find_at( node_type * pHead, Q& val, Compare cmp, Func f )
1117 search( pHead, val, pos, cmp );
1118 if ( pos.pCur != &m_Tail ) {
1119 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
1120 if ( !pos.pCur->is_marked()
1121 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
1123 f( *node_traits::to_value_ptr( *pos.pCur ), val );
1130 template <typename Q, typename Compare>
1131 bool find_at( node_type * pHead, Q const& val, Compare cmp )
1135 search( pHead, val, pos, cmp );
1136 return pos.pCur != &m_Tail
1137 && !pos.pCur->is_marked()
1138 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0;
1141 template <typename Q, typename Compare>
1142 bool get_at( node_type * pHead, typename guarded_ptr::native_guard& gp, Q const& val, Compare cmp )
1146 search( pHead, val, pos, cmp );
1147 if ( pos.pCur != &m_Tail
1148 && !pos.pCur->is_marked()
1149 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
1151 gp.set( pos.guards.template get<value_type>( position::guard_current_item ));
1161 template <typename Q, typename Compare>
1162 void search( node_type * pHead, const Q& key, position& pos, Compare cmp )
1164 node_type const* pTail = &m_Tail;
1166 marked_node_ptr pCur( pHead );
1167 marked_node_ptr pPrev( pHead );
1169 while ( pCur.ptr() != pTail ) {
1170 if ( pCur.ptr() != pHead ) {
1171 if ( cmp( *node_traits::to_value_ptr( *pCur.ptr()), key ) >= 0 )
1175 pos.guards.copy( position::guard_prev_item, position::guard_current_item );
1178 pCur = pos.guards.protect( position::guard_current_item, pPrev->m_pNext,
1179 []( marked_node_ptr p ) { return node_traits::to_value_ptr( p.ptr()); }
1181 assert( pCur.ptr() != nullptr );
1183 pPrev = pCur = pHead;
1186 pos.pCur = pCur.ptr();
1187 pos.pPred = pPrev.ptr();
1190 static bool validate( node_type * pPred, node_type * pCur )
1192 return !pPred->is_marked()
1193 && !pCur->is_marked()
1194 && pPred->m_pNext.load(memory_model::memory_order_relaxed) == pCur;
1199 }} // namespace cds::intrusive
1201 #endif // CDSLIB_INTRUSIVE_IMPL_LAZY_LIST_H