3 #ifndef __CDS_INTRUSIVE_IMPL_LAZY_LIST_H
4 #define __CDS_INTRUSIVE_IMPL_LAZY_LIST_H
6 #include <mutex> // unique_lock
7 #include <cds/intrusive/details/lazy_list_base.h>
9 namespace cds { namespace intrusive {
11 /// Lazy ordered single-linked list
12 /** @ingroup cds_intrusive_list
13 \anchor cds_intrusive_LazyList_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 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
20 "A Lazy Concurrent List-Based Set Algorithm"
22 The lazy list is based on an optimistic locking scheme for inserts and removes,
23 eliminating the need to use the equivalent of an atomically markable
24 reference. It also has a novel wait-free membership \p find operation
25 that does not need to perform cleanup operations and is more efficient.
28 - \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).
29 - \p T - type to be stored in the list. The type must be based on lazy_list::node (for lazy_list::base_hook)
30 or it must have a member of type lazy_list::node (for lazy_list::member_hook).
31 - \p Traits - type traits. See lazy_list::traits for explanation.
32 It is possible to declare option-based list with cds::intrusive::lazy_list::make_traits metafunction istead of \p Traits template
33 argument. For example, the following traits-based declaration of \p gc::HP lazy list
35 #include <cds/intrusive/lazy_list_hp.h>
36 // Declare item stored in your list
37 struct item: public cds::intrusive::lazy_list::node< cds::gc::HP >
40 // Declare comparator for the item
41 struct my_compare { ... }
44 struct my_traits: public cds::intrusive::lazy_list::traits
46 typedef cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::HP > > hook;
47 typedef my_compare compare;
50 // Declare traits-based list
51 typedef cds::intrusive::LazyList< cds::gc::HP, item, my_traits > traits_based_list;
53 is equivalent for the following option-based list
55 #include <cds/intrusive/lazy_list_hp.h>
57 // item struct and my_compare are the same
59 // Declare option-based list
60 typedef cds::intrusive::LazyList< cds::gc::HP, item,
61 typename cds::intrusive::lazy_list::make_traits<
62 cds::intrusive::opt::hook< cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::HP > > > // hook option
63 ,cds::intrusive::opt::compare< my_compare > // item comparator option
69 There are different specializations of this template for each garbage collecting schema used.
70 You should select GC needed and include appropriate .h-file:
71 - for gc::HP: \code #include <cds/intrusive/lazy_list_hp.h> \endcode
72 - for gc::DHP: \code #include <cds/intrusive/lazy_list_dhp.h> \endcode
73 - for gc::nogc: \code #include <cds/intrusive/lazy_list_nogc.h> \endcode
74 - for \ref cds_urcu_type "RCU" - see \ref cds_intrusive_LazyList_rcu "LazyList RCU specialization"
76 Then, you should incorporate lazy_list::node into your struct \p T and provide
77 appropriate \p lazy_list::traits::hook in your \p Traits template parameters. Usually, for \p Traits
78 a struct based on \p lazy_list::traits should be defined.
80 Example for gc::DHP and base hook:
82 // Include GC-related lazy list specialization
83 #include <cds/intrusive/lazy_list_dhp.h>
85 // Data stored in lazy list
86 struct my_data: public cds::intrusive::lazy_list::node< cds::gc::DHP >
95 // my_data comparing functor
97 int operator()( const my_data& d1, const my_data& d2 )
99 return d1.strKey.compare( d2.strKey );
102 int operator()( const my_data& d, const std::string& s )
104 return d.strKey.compare(s);
107 int operator()( const std::string& s, const my_data& d )
109 return s.compare( d.strKey );
114 struct my_traits: public cds::intrusive::lazy_list::traits
116 typedef cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::DHP > > hook;
117 typedef my_data_cmp compare;
121 typedef cds::intrusive::LazyList< cds::gc::DHP, my_data, my_traits > traits_based_list;
124 Equivalent option-based code:
126 // GC-related specialization
127 #include <cds/intrusive/lazy_list_dhp.h>
136 // Declare option-based list
137 typedef cds::intrusive::LazyList< cds::gc::DHP
139 , typename cds::intrusive::lazy_list::make_traits<
140 cds::intrusive::opt::hook< cds::intrusive::lazy_list::base_hook< cds::opt::gc< cds::gc::DHP > > >
141 ,cds::intrusive::opt::compare< my_data_cmp >
150 #ifdef CDS_DOXYGEN_INVOKED
151 ,class Traits = lazy_list::traits
159 typedef GC gc; ///< Garbage collector
160 typedef T value_type; ///< type of value stored in the list
161 typedef Traits traits; ///< Traits template parameter
163 typedef typename traits::hook hook; ///< hook type
164 typedef typename hook::node_type node_type; ///< node type
166 # ifdef CDS_DOXYGEN_INVOKED
167 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
169 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
172 typedef typename traits::disposer disposer; ///< disposer
173 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits; ///< node traits
174 typedef typename lazy_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
176 typedef typename traits::back_off back_off ; ///< back-off strategy
177 typedef typename traits::item_counter item_counter ; ///< Item counting policy used
178 typedef typename traits::memory_model memory_model; ///< C++ memory ordering (see \p lazy_list::traits::memory_model)
180 typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
183 // Rebind traits (split-list support)
184 template <typename... Options>
185 struct rebind_traits {
189 , typename cds::opt::make_options< traits, Options...>::type
195 typedef typename node_type::marked_ptr marked_node_ptr; ///< Node marked pointer
196 typedef node_type * auxiliary_head; ///< Auxiliary head type (for split-list support)
203 item_counter m_ItemCounter ; ///< Item counter
206 struct clean_disposer {
207 void operator()( value_type * p )
209 lazy_list::node_cleaner<gc, node_type, memory_model>()( node_traits::to_node_ptr( p ) );
214 /// Position pointer for item search
216 node_type * pPred ; ///< Previous node
217 node_type * pCur ; ///< Current node
219 typename gc::template GuardArray<2> guards ; ///< Guards array
226 /// Locks nodes \p pPred and \p pCur
229 pPred->m_Lock.lock();
233 /// Unlocks nodes \p pPred and \p pCur
236 pCur->m_Lock.unlock();
237 pPred->m_Lock.unlock();
241 class auto_lock_position {
244 auto_lock_position( position& pos )
249 ~auto_lock_position()
258 void link_node( node_type * pNode, node_type * pPred, node_type * pCur )
260 assert( pPred->m_pNext.load(memory_model::memory_order_relaxed).ptr() == pCur );
262 pNode->m_pNext.store( marked_node_ptr(pCur), memory_model::memory_order_release );
263 pPred->m_pNext.store( marked_node_ptr(pNode), memory_model::memory_order_release );
266 void unlink_node( node_type * pPred, node_type * pCur, node_type * pHead )
268 assert( pPred->m_pNext.load(memory_model::memory_order_relaxed).ptr() == pCur );
270 node_type * pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr();
271 //pCur->m_pNext.store( marked_node_ptr( pNext, 1), memory_model::memory_order_release) ; // logically deleting
272 pCur->m_pNext.store( marked_node_ptr( pHead, 1 ), memory_model::memory_order_release ) ; // logical removal + back-link for search
273 pPred->m_pNext.store( marked_node_ptr( pNext ), memory_model::memory_order_release); // physically deleting
274 //pCur->m_pNext.store( marked_node_ptr( pHead, 1 ), memory_model::memory_order_release ) ; // back-link for search
277 void retire_node( node_type * pNode )
279 assert( pNode != nullptr );
280 gc::template retire<clean_disposer>( node_traits::to_value_ptr( *pNode ) );
286 template <bool IsConst>
289 friend class LazyList;
292 value_type * m_pNode;
293 typename gc::Guard m_Guard;
297 assert( m_pNode != nullptr );
300 typename gc::Guard g;
301 node_type * pCur = node_traits::to_node_ptr( m_pNode );
302 if ( pCur->m_pNext.load( memory_model::memory_order_relaxed ).ptr() != nullptr ) { // if pCur is not tail node
305 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr();
306 g.assign( node_traits::to_value_ptr( pNext ));
307 } while ( pNext != pCur->m_pNext.load(memory_model::memory_order_relaxed).ptr() );
309 m_pNode = m_Guard.assign( g.template get<value_type>() );
316 if ( m_pNode != nullptr ) {
317 typename gc::Guard g;
318 node_type * pNode = node_traits::to_node_ptr( m_pNode );
320 // Dummy tail node could not be marked
321 while ( pNode->is_marked() ) {
322 node_type * p = pNode->m_pNext.load(memory_model::memory_order_relaxed).ptr();
323 g.assign( node_traits::to_value_ptr( p ));
324 if ( p == pNode->m_pNext.load(memory_model::memory_order_relaxed).ptr() )
327 if ( pNode != node_traits::to_node_ptr( m_pNode ) )
328 m_pNode = m_Guard.assign( g.template get<value_type>() );
332 iterator_type( node_type * pNode )
334 m_pNode = m_Guard.assign( node_traits::to_value_ptr( pNode ));
339 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
340 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
346 iterator_type( iterator_type const& src )
349 m_pNode = m_Guard.assign( src.m_pNode );
355 value_ptr operator ->() const
360 value_ref operator *() const
362 assert( m_pNode != nullptr );
367 iterator_type& operator ++()
374 iterator_type& operator = (iterator_type const& src)
376 m_pNode = src.m_pNode;
377 m_Guard.assign( m_pNode );
382 bool operator ==(iterator_type<C> const& i ) const
384 return m_pNode == i.m_pNode;
387 bool operator !=(iterator_type<C> const& i ) const
389 return m_pNode != i.m_pNode;
397 The forward iterator for lazy list has some features:
398 - it has no post-increment operator
399 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
400 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
401 may be thrown if a limit of guard count per thread is exceeded.
402 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
403 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
404 deleting operations it is no guarantee that you iterate all item in the list.
406 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
407 for debug purpose only.
409 typedef iterator_type<false> iterator;
410 /// Const forward iterator
412 For iterator's features and requirements see \ref iterator
414 typedef iterator_type<true> const_iterator;
416 /// Returns a forward iterator addressing the first element in a list
418 For empty list \code begin() == end() \endcode
422 iterator it( &m_Head );
423 ++it ; // skip dummy head
427 /// Returns an iterator that addresses the location succeeding the last element in a list
429 Do not use the value returned by <tt>end</tt> function to access any item.
431 The returned value can be used only to control reaching the end of the list.
432 For empty list \code begin() == end() \endcode
436 return iterator( &m_Tail );
439 /// Returns a forward const iterator addressing the first element in a list
441 const_iterator begin() const
443 return get_const_begin();
445 const_iterator cbegin() const
447 return get_const_begin();
451 /// Returns an const iterator that addresses the location succeeding the last element in a list
453 const_iterator end() const
455 return get_const_end();
457 const_iterator cend() const
459 return get_const_end();
465 const_iterator get_const_begin() const
467 const_iterator it( const_cast<node_type *>( &m_Head ));
468 ++it ; // skip dummy head
471 const_iterator get_const_end() const
473 return const_iterator( const_cast<node_type *>(&m_Tail) );
478 /// 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" );
482 m_Head.m_pNext.store( marked_node_ptr( &m_Tail ), memory_model::memory_order_relaxed );
485 /// Destroys the list object
489 assert( m_Head.m_pNext.load( memory_model::memory_order_relaxed ).ptr() == &m_Tail );
490 m_Head.m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
495 The function inserts \p val in the list if the list does not contain
496 an item with key equal to \p val.
498 Returns \p true if \p val is linked into the list, \p false otherwise.
500 bool insert( value_type& val )
502 return insert_at( &m_Head, val );
507 This function is intended for derived non-intrusive containers.
509 The function allows to split new item creating into two part:
510 - create item with key only
511 - insert new item into the list
512 - if inserting is success, calls \p f functor to initialize value-field of \p val.
514 The functor signature is:
516 void func( value_type& val );
518 where \p val is the item inserted.
519 While the functor \p f is called the item \p val is locked so
520 the functor has an exclusive access to the item.
521 The user-defined functor is called only if the inserting is success.
523 template <typename Func>
524 bool insert( value_type& val, Func f )
526 return insert_at( &m_Head, val, f );
529 /// Ensures that the \p item exists in the list
531 The operation performs inserting or changing data with lock-free manner.
533 If the item \p val not found in the list, then \p val is inserted into the list.
534 Otherwise, the functor \p func is called with item found.
535 The functor signature is:
537 void func( bool bNew, value_type& item, value_type& val );
540 - \p bNew - \p true if the item has been inserted, \p false otherwise
541 - \p item - item of the list
542 - \p val - argument \p val passed into the \p ensure function
543 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
544 refer to the same thing.
546 The functor may change non-key fields of the \p item.
547 While the functor \p f is working the item \p item is locked,
548 so \p f has exclusive access to the item.
550 Returns std::pair<bool, bool> where \p first is \p true if operation is successfull,
551 \p second is \p true if new item has been added or \p false if the item with \p key
552 already is in the list.
554 template <typename Func>
555 std::pair<bool, bool> ensure( value_type& val, Func func )
557 return ensure_at( &m_Head, val, func );
560 /// Unlinks the item \p val from the list
562 The function searches the item \p val in the list and unlink it from the list
563 if it is found and it is equal to \p val.
565 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
566 and deletes the item found. \p unlink finds an item by key and deletes it
567 only if \p val is an item of that list, i.e. the pointer to item found
568 is equal to <tt> &val </tt>.
570 The function returns \p true if success and \p false otherwise.
572 bool unlink( value_type& val )
574 return unlink_at( &m_Head, val );
577 /// Deletes the item from the list
578 /** \anchor cds_intrusive_LazyList_hp_erase_val
579 The function searches an item with key equal to \p key in the list,
580 unlinks it from the list, and returns \p true.
581 If the item with the key equal to \p key is not found the function return \p false.
583 template <typename Q>
584 bool erase( Q const& key )
586 return erase_at( &m_Head, key, key_comparator() );
589 /// Deletes the item from the list using \p pred predicate for searching
591 The function is an analog of \ref cds_intrusive_LazyList_hp_erase_val "erase(Q const&)"
592 but \p pred is used for key comparing.
593 \p Less functor has the interface like \p std::less.
594 \p pred must imply the same element order as the comparator used for building the list.
596 template <typename Q, typename Less>
597 bool erase_with( Q const& key, Less pred )
599 return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>() );
602 /// Deletes the item from the list
603 /** \anchor cds_intrusive_LazyList_hp_erase_func
604 The function searches an item with key equal to \p key in the list,
605 call \p func functor with item found, unlinks it from the list, and returns \p true.
606 The \p Func interface is
609 void operator()( value_type const& item );
613 If \p key is not found the function return \p false.
615 template <typename Q, typename Func>
616 bool erase( const Q& key, Func func )
618 return erase_at( &m_Head, key, key_comparator(), func );
621 /// Deletes the item from the list using \p pred predicate for searching
623 The function is an analog of \ref cds_intrusive_LazyList_hp_erase_func "erase(Q const&, Func)"
624 but \p pred is used for key comparing.
625 \p Less functor has the interface like \p std::less.
626 \p pred must imply the same element order as the comparator used for building the list.
628 template <typename Q, typename Less, typename Func>
629 bool erase_with( const Q& key, Less pred, Func func )
631 return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), func );
634 /// Extracts the item from the list with specified \p key
635 /** \anchor cds_intrusive_LazyList_hp_extract
636 The function searches an item with key equal to \p key,
637 unlinks it from the list, and returns it as \p guarded_ptr.
638 If \p key is not found the function returns an empty guarded pointer.
640 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
642 The \ref disposer specified in \p Traits class template parameter is called automatically
643 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
644 will be destroyed or released.
645 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
649 typedef cds::intrusive::LazyList< cds::gc::HP, foo, my_traits > ord_list;
653 ord_list::guarded_ptr gp( theList.extract( 5 ));
657 // Destructor of gp releases internal HP guard
661 template <typename Q>
662 guarded_ptr extract( Q const& key )
665 extract_at( &m_Head, gp.guard(), key, key_comparator() );
669 /// Extracts the item from the list with comparing functor \p pred
671 The function is an analog of \ref cds_intrusive_LazyList_hp_extract "extract(Q const&)"
672 but \p pred predicate is used for key comparing.
674 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
676 \p pred must imply the same element order as the comparator used for building the list.
678 template <typename Q, typename Less>
679 guarded_ptr extract_with( Q const& key, Less pred )
682 extract_at( &m_Head, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>() );
686 /// Finds the key \p key
687 /** \anchor cds_intrusive_LazyList_hp_find
688 The function searches the item with key equal to \p key and calls the functor \p f for item found.
689 The interface of \p Func functor is:
692 void operator()( value_type& item, Q& key );
695 where \p item is the item found, \p key is the <tt>find</tt> function argument.
697 The functor may change non-key fields of \p item.
698 While the functor \p f is calling the item \p item is locked.
700 The function returns \p true if \p key is found, \p false otherwise.
702 template <typename Q, typename Func>
703 bool find( Q& key, Func f )
705 return find_at( &m_Head, key, key_comparator(), f );
708 template <typename Q, typename Func>
709 bool find( Q const& key, Func f )
711 return find_at( &m_Head, key, key_comparator(), f );
715 /// Finds the key \p key using \p pred predicate for searching
717 The function is an analog of \ref cds_intrusive_LazyList_hp_find "find(Q&, Func)"
718 but \p pred is used for key comparing.
719 \p Less functor has the interface like \p std::less.
720 \p pred must imply the same element order as the comparator used for building the list.
722 template <typename Q, typename Less, typename Func>
723 bool find_with( Q& key, Less pred, Func f )
725 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
728 template <typename Q, typename Less, typename Func>
729 bool find_with( Q const& key, Less pred, Func f )
731 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
735 /// Finds the key \p key
736 /** \anchor cds_intrusive_LazyList_hp_find_val
737 The function searches the item with key equal to \p key
738 and returns \p true if it is found, and \p false otherwise
740 template <typename Q>
741 bool find( Q const& key )
743 return find_at( &m_Head, key, key_comparator() );
746 /// Finds \p key using \p pred predicate for searching
748 The function is an analog of \ref cds_intrusive_LazyList_hp_find_val "find(Q const&)"
749 but \p pred is used for key comparing.
750 \p Less functor has the interface like \p std::less.
751 \p pred must imply the same element order as the comparator used for building the list.
753 template <typename Q, typename Less>
754 bool find_with( Q const& key, Less pred )
756 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>() );
759 /// Finds \p key and return the item found
760 /** \anchor cds_intrusive_LazyList_hp_get
761 The function searches the item with key equal to \p key
762 and returns an guarded pointer to it.
763 If \p key is not found the function returns an empty guarded pointer.
765 The \ref disposer specified in \p Traits class template parameter is called
766 by garbage collector \p GC automatically when returned \p guarded_ptr object
767 will be destroyed or released.
768 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
772 typedef cds::intrusive::LazyList< cds::gc::HP, foo, my_traits > ord_list;
776 ord_list::guarded_ptr gp(theList.get( 5 ));
781 // Destructor of guarded_ptr releases internal HP guard
785 Note the compare functor specified for class \p Traits template parameter
786 should accept a parameter of type \p Q that can be not the same as \p value_type.
788 template <typename Q>
789 guarded_ptr get( Q const& key )
792 get_at( &m_Head, gp.guard(), key, key_comparator() );
796 /// Finds \p key and return the item found
798 The function is an analog of \ref cds_intrusive_LazyList_hp_get "get( Q const&)"
799 but \p pred is used for comparing the keys.
801 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
803 \p pred must imply the same element order as the comparator used for building the list.
805 template <typename Q, typename Less>
806 guarded_ptr get_with( Q const& key, Less pred )
809 get_at( &m_Head, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>() );
816 typename gc::Guard guard;
819 h = m_Head.m_pNext.load( memory_model::memory_order_relaxed );
820 guard.assign( node_traits::to_value_ptr( h.ptr() ));
821 if ( m_Head.m_pNext.load(memory_model::memory_order_acquire) == h ) {
822 m_Head.m_Lock.lock();
825 unlink_node( &m_Head, h.ptr(), &m_Head );
828 m_Head.m_Lock.unlock();
830 retire_node( h.ptr() ) ; // free node
835 /// Checks if the list is empty
838 return m_Head.m_pNext.load( memory_model::memory_order_relaxed ).ptr() == &m_Tail;
841 /// Returns list's item count
843 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
844 this function always returns 0.
846 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
847 is empty. To check list emptyness use \p empty() method.
851 return m_ItemCounter.value();
856 // split-list support
857 bool insert_aux_node( node_type * pNode )
859 return insert_aux_node( &m_Head, pNode );
862 // split-list support
863 bool insert_aux_node( node_type * pHead, node_type * pNode )
865 assert( pNode != nullptr );
867 // Hack: convert node_type to value_type.
868 // In principle, auxiliary node cannot be reducible to value_type
869 // We assume that internal comparator can correctly distinguish aux and regular node.
870 return insert_at( pHead, *node_traits::to_value_ptr( pNode ) );
873 bool insert_at( node_type * pHead, value_type& val )
875 link_checker::is_empty( node_traits::to_node_ptr( val ) );
880 search( pHead, val, pos, key_comparator() );
882 auto_lock_position alp( pos );
883 if ( validate( pos.pPred, pos.pCur )) {
884 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
885 // failed: key already in list
889 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
898 template <typename Func>
899 bool insert_at( node_type * pHead, value_type& val, Func f )
901 link_checker::is_empty( node_traits::to_node_ptr( val ) );
906 search( pHead, val, pos, key_comparator() );
908 auto_lock_position alp( pos );
909 if ( validate( pos.pPred, pos.pCur )) {
910 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
911 // failed: key already in list
915 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
925 template <typename Func>
926 std::pair<bool, bool> ensure_at( node_type * pHead, value_type& val, Func func )
932 search( pHead, val, pos, key_comparator() );
934 auto_lock_position alp( pos );
935 if ( validate( pos.pPred, pos.pCur )) {
936 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
937 // key already in the list
939 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
940 return std::make_pair( true, false );
944 link_checker::is_empty( node_traits::to_node_ptr( val ) );
946 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
947 func( true, val, val );
949 return std::make_pair( true, true );
956 bool unlink_at( node_type * pHead, value_type& val )
962 search( pHead, val, pos, key_comparator() );
966 auto_lock_position alp( pos );
967 if ( validate( pos.pPred, pos.pCur ) ) {
968 if ( pos.pCur != &m_Tail
969 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0
970 && node_traits::to_value_ptr( pos.pCur ) == &val )
973 unlink_node( pos.pPred, pos.pCur, pHead );
983 retire_node( pos.pCur );
992 template <typename Q, typename Compare, typename Func>
993 bool erase_at( node_type * pHead, const Q& val, Compare cmp, Func f, position& pos )
996 search( pHead, val, pos, cmp );
1000 auto_lock_position alp( pos );
1001 if ( validate( pos.pPred, pos.pCur )) {
1002 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
1004 unlink_node( pos.pPred, pos.pCur, pHead );
1005 f( *node_traits::to_value_ptr( *pos.pCur ) );
1015 if ( nResult > 0 ) {
1016 retire_node( pos.pCur );
1025 template <typename Q, typename Compare, typename Func>
1026 bool erase_at( node_type * pHead, const Q& val, Compare cmp, Func f )
1029 return erase_at( pHead, val, cmp, f, pos );
1032 template <typename Q, typename Compare>
1033 bool erase_at( node_type * pHead, const Q& val, Compare cmp )
1036 return erase_at( pHead, val, cmp, [](value_type const &){}, pos );
1039 template <typename Q, typename Compare>
1040 bool extract_at( node_type * pHead, typename guarded_ptr::native_guard& gp, const Q& val, Compare cmp )
1043 if ( erase_at( pHead, val, cmp, [](value_type const &){}, pos )) {
1044 gp.set( pos.guards.template get<value_type>(position::guard_current_item) );
1050 template <typename Q, typename Compare, typename Func>
1051 bool find_at( node_type * pHead, Q& val, Compare cmp, Func f )
1055 search( pHead, val, pos, cmp );
1056 if ( pos.pCur != &m_Tail ) {
1057 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
1058 if ( !pos.pCur->is_marked()
1059 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
1061 f( *node_traits::to_value_ptr( *pos.pCur ), val );
1068 template <typename Q, typename Compare>
1069 bool find_at( node_type * pHead, Q const& val, Compare cmp )
1073 search( pHead, val, pos, cmp );
1074 return pos.pCur != &m_Tail
1075 && !pos.pCur->is_marked()
1076 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0;
1079 template <typename Q, typename Compare>
1080 bool get_at( node_type * pHead, typename guarded_ptr::native_guard& gp, Q const& val, Compare cmp )
1084 search( pHead, val, pos, cmp );
1085 if ( pos.pCur != &m_Tail
1086 && !pos.pCur->is_marked()
1087 && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
1089 gp.set( pos.guards.template get<value_type>( position::guard_current_item ));
1099 template <typename Q, typename Compare>
1100 void search( node_type * pHead, const Q& key, position& pos, Compare cmp )
1102 const node_type * pTail = &m_Tail;
1104 marked_node_ptr pCur( pHead );
1105 marked_node_ptr pPrev( pHead );
1109 while ( pCur.ptr() != pTail )
1111 if ( pCur.ptr() != pHead ) {
1112 if ( cmp( *node_traits::to_value_ptr( *pCur.ptr() ), key ) >= 0 )
1116 pos.guards.copy( position::guard_prev_item, position::guard_current_item );
1120 pCur = pPrev->m_pNext.load(memory_model::memory_order_relaxed);
1121 pos.guards.assign( position::guard_current_item, node_traits::to_value_ptr( pCur.ptr() ));
1122 if ( pCur == pPrev->m_pNext.load(memory_model::memory_order_acquire) )
1126 assert( pCur.ptr() != nullptr );
1129 pos.pCur = pCur.ptr();
1130 pos.pPred = pPrev.ptr();
1133 static bool validate( node_type * pPred, node_type * pCur )
1135 return !pPred->is_marked()
1136 && !pCur->is_marked()
1137 && pPred->m_pNext.load(memory_model::memory_order_relaxed) == pCur;
1142 }} // namespace cds::intrusive
1144 #endif // __CDS_INTRUSIVE_IMPL_LAZY_LIST_H