3 #ifndef CDSLIB_INTRUSIVE_MICHAEL_LIST_RCU_H
4 #define CDSLIB_INTRUSIVE_MICHAEL_LIST_RCU_H
6 #include <cds/intrusive/details/michael_list_base.h>
7 #include <cds/urcu/details/check_deadlock.h>
8 #include <cds/details/binary_functor_wrapper.h>
9 #include <cds/details/make_const_type.h>
10 #include <cds/urcu/exempt_ptr.h>
12 namespace cds { namespace intrusive {
14 /// Michael's lock-free ordered single-linked list (template specialization for \ref cds_urcu_desc "RCU")
15 /** @ingroup cds_intrusive_list
16 \anchor cds_intrusive_MichaelList_rcu
18 Usually, ordered single-linked list is used as a building block for the hash table implementation.
19 The complexity of searching is <tt>O(N)</tt>.
22 - \p RCU - one of \ref cds_urcu_gc "RCU type"
23 - \p T - type to be stored in the list; the type \p T should be based on (or has a member of type)
24 cds::intrusive::micheal_list::node
25 - \p Traits - type traits. See \p michael_list::traits for explanation. It is possible to declare option-based
26 list with \p cds::intrusive::michael_list::make_traits metafunction,
27 see \ref cds_intrusive_MichaelList_hp "here" for explanations.
30 Before including <tt><cds/intrusive/michael_list_rcu.h></tt> you should include appropriate RCU header file,
31 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
32 For example, for \ref cds_urcu_general_buffered_gc "general-purpose buffered RCU" you should include:
34 #include <cds/urcu/general_buffered.h>
35 #include <cds/intrusive/michael_list_rcu.h>
37 // Now, you can declare Michael's list for type Foo and default traits:
38 typedef cds::intrusive::MichaelList<cds::urcu::gc< cds::urcu::general_buffered<> >, Foo > rcu_michael_list;
41 template < typename RCU, typename T,
42 #ifdef CDS_DOXYGEN_INVOKED
43 class Traits = michael_list::traits
48 class MichaelList<cds::urcu::gc<RCU>, T, Traits>
51 typedef T value_type; ///< type of value stored in the list
52 typedef Traits traits; ///< Traits template parameter
54 typedef typename traits::hook hook; ///< hook type
55 typedef typename hook::node_type node_type; ///< node type
57 # ifdef CDS_DOXYGEN_INVOKED
58 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
60 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
63 typedef typename traits::disposer disposer; ///< disposer used
64 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
65 typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
67 typedef cds::urcu::gc<RCU> gc; ///< RCU schema
68 typedef typename traits::back_off back_off; ///< back-off strategy
69 typedef typename traits::item_counter item_counter; ///< Item counting policy used
70 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
71 typedef typename traits::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
73 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
74 static CDS_CONSTEXPR const bool c_bExtractLockExternal = true; ///< Group of \p extract_xxx functions require external locking
77 // Rebind traits (split-list support)
78 template <typename... Options>
79 struct rebind_traits {
83 , typename cds::opt::make_options< traits, Options...>::type
89 typedef typename node_type::marked_ptr marked_node_ptr ; ///< Marked node pointer
90 typedef typename node_type::atomic_marked_ptr atomic_node_ptr ; ///< Atomic node pointer
91 typedef atomic_node_ptr auxiliary_head ; ///< Auxiliary head type (for split-list support)
93 atomic_node_ptr m_pHead ; ///< Head pointer
94 item_counter m_ItemCounter ; ///< Item counter
97 /// Position pointer for item search
99 atomic_node_ptr * pPrev ; ///< Previous node
100 node_type * pCur ; ///< Current node
101 node_type * pNext ; ///< Next node
104 typedef cds::urcu::details::check_deadlock_policy< gc, rcu_check_deadlock> check_deadlock_policy;
106 static void clear_links( node_type * pNode )
108 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
111 struct clear_and_dispose {
112 void operator()( value_type * p )
114 assert( p != nullptr );
115 clear_links( node_traits::to_node_ptr(p));
122 using exempt_ptr = cds::urcu::exempt_ptr< gc, value_type, value_type, clear_and_dispose, void >; ///< pointer to extracted node
127 static void dispose_node( node_type * pNode )
130 assert( !gc::is_locked() );
132 gc::template retire_ptr<clear_and_dispose>( node_traits::to_value_ptr( *pNode ) );
135 bool link_node( node_type * pNode, position& pos )
137 assert( pNode != nullptr );
138 link_checker::is_empty( pNode );
140 marked_node_ptr p( pos.pCur );
141 pNode->m_pNext.store( p, memory_model::memory_order_release );
142 return pos.pPrev->compare_exchange_strong( p, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed );
145 bool unlink_node( position& pos )
147 // Mark the node (logical deleting)
148 marked_node_ptr next(pos.pNext, 0);
149 if ( pos.pCur->m_pNext.compare_exchange_strong( next, marked_node_ptr(pos.pNext, 1), memory_model::memory_order_release, atomics::memory_order_relaxed )) {
150 marked_node_ptr cur(pos.pCur);
151 if ( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr( pos.pNext ), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))
154 CDS_VERIFY( pos.pCur->m_pNext.compare_exchange_strong( next, next ^ 1, memory_model::memory_order_relaxed, atomics::memory_order_relaxed ));
162 template <bool IsConst>
165 friend class MichaelList;
166 value_type * m_pNode;
171 node_type * p = node_traits::to_node_ptr( *m_pNode )->m_pNext.load(memory_model::memory_order_relaxed).ptr();
172 m_pNode = p ? node_traits::to_value_ptr( p ) : nullptr;
177 explicit iterator_type( node_type * pNode)
180 m_pNode = node_traits::to_value_ptr( *pNode );
184 explicit iterator_type( atomic_node_ptr const& refNode)
186 node_type * pNode = refNode.load(memory_model::memory_order_relaxed).ptr();
187 m_pNode = pNode ? node_traits::to_value_ptr( *pNode ) : nullptr;
191 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
192 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
198 iterator_type( const iterator_type& src )
199 : m_pNode( src.m_pNode )
202 value_ptr operator ->() const
207 value_ref operator *() const
209 assert( m_pNode != nullptr );
214 iterator_type& operator ++()
221 iterator_type operator ++(int)
223 iterator_type i(*this);
228 iterator_type& operator = (const iterator_type& src)
230 m_pNode = src.m_pNode;
235 bool operator ==(iterator_type<C> const& i ) const
237 return m_pNode == i.m_pNode;
240 bool operator !=(iterator_type<C> const& i ) const
242 return m_pNode != i.m_pNode;
249 typedef iterator_type<false> iterator;
250 /// Const forward iterator
251 typedef iterator_type<true> const_iterator;
253 /// Returns a forward iterator addressing the first element in a list
255 For empty list \code begin() == end() \endcode
259 return iterator( m_pHead );
262 /// Returns an iterator that addresses the location succeeding the last element in a list
264 Do not use the value returned by <tt>end</tt> function to access any item.
265 Internally, <tt>end</tt> returning value equals to \p nullptr.
267 The returned value can be used only to control reaching the end of the list.
268 For empty list \code begin() == end() \endcode
275 /// Returns a forward const iterator addressing the first element in a list
276 const_iterator begin() const
278 return const_iterator(m_pHead );
280 /// Returns a forward const iterator addressing the first element in a list
281 const_iterator cbegin() const
283 return const_iterator(m_pHead );
286 /// Returns an const iterator that addresses the location succeeding the last element in a list
287 const_iterator end() const
289 return const_iterator();
291 /// Returns an const iterator that addresses the location succeeding the last element in a list
292 const_iterator cend() const
294 return const_iterator();
298 /// Default constructor initializes empty list
302 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
313 The function inserts \p val in the list if the list does not contain
314 an item with key equal to \p val.
316 The function makes RCU lock internally.
318 Returns \p true if \p val is linked into the list, \p false otherwise.
320 bool insert( value_type& val )
322 return insert_at( m_pHead, val );
327 This function is intended for derived non-intrusive containers.
329 The function allows to split new item creating into two part:
330 - create item with key only
331 - insert new item into the list
332 - if inserting is success, calls \p f functor to initialize value-field of \p val.
334 The functor signature is:
336 void func( value_type& val );
338 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
339 \p val no any other changes could be made on this list's item by concurrent threads.
340 The user-defined functor is called only if the inserting is success.
342 The function makes RCU lock internally.
344 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
346 template <typename Func>
347 bool insert( value_type& val, Func f )
349 return insert_at( m_pHead, val, f );
352 /// Ensures that the \p item exists in the list
354 The operation performs inserting or changing data with lock-free manner.
356 If the item \p val not found in the list, then \p val is inserted into the list.
357 Otherwise, the functor \p func is called with item found.
358 The functor signature is:
361 void operator()( bool bNew, value_type& item, value_type& val );
365 - \p bNew - \p true if the item has been inserted, \p false otherwise
366 - \p item - item of the list
367 - \p val - argument \p val passed into the \p ensure function
368 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
369 refer to the same thing.
371 The functor may change non-key fields of the \p item; however, \p func must guarantee
372 that during changing no any other modifications could be made on this item by concurrent threads.
374 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
375 \p second is true if new item has been added or \p false if the item with \p key
376 already is in the list.
378 The function makes RCU lock internally.
380 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
382 template <typename Func>
383 std::pair<bool, bool> ensure( value_type& val, Func func )
385 return ensure_at( m_pHead, val, func );
388 /// Unlinks the item \p val from the list
390 The function searches the item \p val in the list and unlink it from the list
391 if it is found and it is equal to \p val.
393 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
394 and deletes the item found. \p unlink finds an item by key and deletes it
395 only if \p val is an item of that list, i.e. the pointer to the item found
396 is equal to <tt> &val </tt>.
398 The function returns \p true if success and \p false otherwise.
400 RCU \p synchronize method can be called.
401 Note that depending on RCU type used the \ref disposer call can be deferred.
403 The function can throw cds::urcu::rcu_deadlock exception if deadlock is encountered and
404 deadlock checking policy is opt::v::rcu_throw_deadlock.
406 bool unlink( value_type& val )
408 return unlink_at( m_pHead, val );
411 /// Deletes the item from the list
412 /** \anchor cds_intrusive_MichaelList_rcu_erase_val
413 The function searches an item with key equal to \p key in the list,
414 unlinks it from the list, and returns \p true.
415 If the item with the key equal to \p key is not found the function return \p false.
417 RCU \p synchronize method can be called.
418 Note that depending on RCU type used the \ref disposer call can be deferred.
420 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
421 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
423 template <typename Q>
424 bool erase( Q const& key )
426 return erase_at( m_pHead, key, key_comparator() );
429 /// Deletes the item from the list using \p pred predicate for searching
431 The function is an analog of \ref cds_intrusive_MichaelList_rcu_erase_val "erase(Q const&)"
432 but \p pred is used for key comparing.
433 \p Less functor has the interface like \p std::less.
434 \p pred must imply the same element order as the comparator used for building the list.
436 template <typename Q, typename Less>
437 bool erase_with( Q const& key, Less pred )
440 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() );
443 /// Deletes the item from the list
444 /** \anchor cds_intrusive_MichaelList_rcu_erase_func
445 The function searches an item with key equal to \p key in the list,
446 call \p func functor with item found, unlinks it from the list, and returns \p true.
447 The \p Func interface is
450 void operator()( value_type const& item );
454 If the item with the key equal to \p key is not found the function return \p false.
456 RCU \p synchronize method can be called.
457 Note that depending on RCU type used the \ref disposer call can be deferred.
459 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
460 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
462 template <typename Q, typename Func>
463 bool erase( Q const& key, Func func )
465 return erase_at( m_pHead, key, key_comparator(), func );
468 /// Deletes the item from the list using \p pred predicate for searching
470 The function is an analog of \ref cds_intrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
471 but \p pred is used for key comparing.
472 \p Less functor has the interface like \p std::less.
473 \p pred must imply the same element order as the comparator used for building the list.
475 template <typename Q, typename Less, typename Func>
476 bool erase_with( Q const& key, Less pred, Func func )
479 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), func );
482 /// Extracts an item from the list
484 @anchor cds_intrusive_MichaelList_rcu_extract
485 The function searches an item with key equal to \p key in the list,
486 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
487 If \p key is not found the function returns an empty \p exempt_ptr.
489 @note The function does NOT call RCU read-side lock or synchronization,
490 and does NOT dispose the item found. It just unlinks the item from the list
491 and returns a pointer to item found.
492 You should lock RCU before calling this function, and you should manually release
493 \p dest exempt pointer outside the RCU lock before reusing the pointer.
496 #include <cds/urcu/general_buffered.h>
497 #include <cds/intrusive/michael_list_rcu.h>
499 typedef cds::urcu::gc< general_buffered<> > rcu;
500 typedef cds::intrusive::MichaelList< rcu, Foo > rcu_michael_list;
502 rcu_michael_list theList;
505 rcu_michael_list::exempt_ptr p1;
507 // first, we should lock RCU
510 // Now, you can apply extract function
511 // Note that you must not delete the item found inside the RCU lock
512 p1 = theList.extract( 10 )
514 // do something with p1
519 // We may safely release p1 here
520 // release() passes the pointer to RCU reclamation cycle:
521 // it invokes RCU retire_ptr function with the disposer you provided for the list.
525 template <typename Q>
526 exempt_ptr extract( Q const& key )
528 return exempt_ptr( extract_at( m_pHead, key, key_comparator() ));
531 /// Extracts an item from the list using \p pred predicate for searching
533 This function is the analog for \p extract(Q const&)
535 The \p pred is a predicate used for key comparing.
536 \p Less has the interface like \p std::less.
537 \p pred must imply the same element order as \ref key_comparator.
539 template <typename Q, typename Less>
540 exempt_ptr extract_with( Q const& key, Less pred )
543 return exempt_ptr( extract_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() ));
546 /// Find the key \p val
547 /** \anchor cds_intrusive_MichaelList_rcu_find_func
548 The function searches the item with key equal to \p key
549 and calls the functor \p f for item found.
550 The interface of \p Func functor is:
553 void operator()( value_type& item, Q& key );
556 where \p item is the item found, \p key is the <tt>find</tt> function argument.
558 The functor can change non-key fields of \p item.
559 The function \p find does not serialize simultaneous access to the list \p item. If such access is
560 possible you must provide your own synchronization schema to exclude unsafe item modifications.
562 The function makes RCU lock internally.
564 The function returns \p true if \p val is found, \p false otherwise.
566 template <typename Q, typename Func>
567 bool find( Q& key, Func f ) const
569 return find_at( const_cast<atomic_node_ptr&>(m_pHead), key, key_comparator(), f );
572 template <typename Q, typename Func>
573 bool find( Q const& key, Func f ) const
575 return find_at( const_cast<atomic_node_ptr&>(m_pHead), key, key_comparator(), f );
579 /// Finds \p key using \p pred predicate for searching
581 The function is an analog of \ref cds_intrusive_MichaelList_rcu_find_func "find(Q&, Func)"
582 but \p pred is used for key comparing.
583 \p Less functor has the interface like \p std::less.
584 \p pred must imply the same element order as the comparator used for building the list.
586 template <typename Q, typename Less, typename Func>
587 bool find_with( Q& key, Less pred, Func f ) const
590 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>(), f );
593 template <typename Q, typename Less, typename Func>
594 bool find_with( Q const& key, Less pred, Func f ) const
597 return find_at( const_cast<atomic_node_ptr&>(m_pHead), key, cds::opt::details::make_comparator_from_less<Less>(), f );
602 /** \anchor cds_intrusive_MichaelList_rcu_find_val
603 The function searches the item with key equal to \p key
604 and returns \p true if \p val found or \p false otherwise.
606 template <typename Q>
607 bool find( Q const& key ) const
609 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, key_comparator() );
612 /// Finds \p key using \p pred predicate for searching
614 The function is an analog of \ref cds_intrusive_MichaelList_rcu_find_val "find(Q const&)"
615 but \p pred is used for key comparing.
616 \p Less functor has the interface like \p std::less.
617 \p pred must imply the same element order as the comparator used for building the list.
619 template <typename Q, typename Less>
620 bool find_with( Q const& key, Less pred ) const
623 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>() );
626 /// Finds \p key and return the item found
627 /** \anchor cds_intrusive_MichaelList_rcu_get
628 The function searches the item with key equal to \p key and returns the pointer to item found.
629 If \p key is not found it returns \p nullptr.
631 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
633 RCU should be locked before call of this function.
634 Returned item is valid only while RCU is locked:
636 typedef cds::intrusive::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
641 ord_list::rcu_lock lock;
643 foo * pVal = theList.get( 5 );
648 // Unlock RCU by rcu_lock destructor
649 // pVal can be retired by disposer at any time after RCU has been unlocked
653 template <typename Q>
654 value_type * get( Q const& key ) const
656 return get_at( const_cast<atomic_node_ptr&>( m_pHead ), key, key_comparator());
659 /// Finds \p key and return the item found
661 The function is an analog of \ref cds_intrusive_MichaelList_rcu_get "get(Q const&)"
662 but \p pred is used for comparing the keys.
664 \p Less functor has the semantics like \p std::less but should take arguments of type \p value_type and \p Q
666 \p pred must imply the same element order as the comparator used for building the list.
668 template <typename Q, typename Less>
669 value_type * get_with( Q const& key, Less pred ) const
672 return get_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>());
675 /// Clears the list using default disposer
677 The function clears the list using default (provided by \p Traits class template argument) disposer functor.
679 RCU \p synchronize method can be called.
680 Note that depending on RCU type used the \ref disposer invocation can be deferred.
682 The function can throw cds::urcu::rcu_deadlock exception if an deadlock is encountered and
683 deadlock checking policy is opt::v::rcu_throw_deadlock.
688 check_deadlock_policy::check();
690 marked_node_ptr pHead;
694 pHead = m_pHead.load(memory_model::memory_order_consume);
697 marked_node_ptr pNext( pHead->m_pNext.load(memory_model::memory_order_relaxed) );
698 if ( !pHead->m_pNext.compare_exchange_weak( pNext, pNext | 1, memory_model::memory_order_acquire, memory_model::memory_order_relaxed ))
700 if ( !m_pHead.compare_exchange_weak( pHead, marked_node_ptr(pNext.ptr()), memory_model::memory_order_release, memory_model::memory_order_relaxed ))
705 dispose_node( pHead.ptr() );
710 /// Check if the list is empty
713 return m_pHead.load( memory_model::memory_order_relaxed ).all() == nullptr;
716 /// Returns list's item count
718 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
719 this function always returns 0.
721 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
722 is empty. To check list emptyness use \p empty() method.
726 return m_ItemCounter.value();
731 // split-list support
732 bool insert_aux_node( node_type * pNode )
734 return insert_aux_node( m_pHead, pNode );
737 // split-list support
738 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
740 assert( pNode != nullptr );
742 // Hack: convert node_type to value_type.
743 // In principle, auxiliary node can be non-reducible to value_type
744 // We assume that comparator can correctly distinguish between aux and regular node.
745 return insert_at( refHead, *node_traits::to_value_ptr( pNode ) );
748 bool insert_at( atomic_node_ptr& refHead, value_type& val, bool bLock = true )
750 link_checker::is_empty( node_traits::to_node_ptr( val ) );
755 if ( search( refHead, val, pos, key_comparator() ) )
758 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
764 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
768 template <typename Func>
769 bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
771 link_checker::is_empty( node_traits::to_node_ptr( val ) );
776 if ( search( refHead, val, pos, key_comparator() ) )
779 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
786 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
790 iterator insert_at_( atomic_node_ptr& refHead, value_type& val, bool bLock = true )
793 if ( insert_at( refHead, val, false ))
794 return iterator( node_traits::to_node_ptr( val ));
798 template <typename Func>
799 std::pair<iterator, bool> ensure_at_( atomic_node_ptr& refHead, value_type& val, Func func, bool bLock = true )
805 if ( search( refHead, val, pos, key_comparator() ) ) {
806 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur ) ) == 0 );
808 func( false, *node_traits::to_value_ptr( *pos.pCur ), val );
809 return std::make_pair( iterator( pos.pCur ), false );
812 link_checker::is_empty( node_traits::to_node_ptr( val ) );
814 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
816 func( true, val , val );
817 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
820 // clear the next field
821 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
826 template <typename Func>
827 std::pair<bool, bool> ensure_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bLock = true )
830 std::pair<iterator, bool> ret = ensure_at_( refHead, val, func, false );
831 return std::make_pair( ret.first != end(), ret.second );
834 bool unlink_at( atomic_node_ptr& refHead, value_type& val )
838 check_deadlock_policy::check();
843 if ( !search( refHead, val, pos, key_comparator() ) || node_traits::to_value_ptr( *pos.pCur ) != &val )
845 if ( !unlink_node( pos )) {
852 dispose_node( pos.pCur );
857 template <typename Q, typename Compare, typename Func>
858 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp, Func f, position& pos )
861 check_deadlock_policy::check();
866 if ( !search( refHead, val, pos, cmp ) )
868 if ( !unlink_node( pos )) {
874 f( *node_traits::to_value_ptr( *pos.pCur ) );
876 dispose_node( pos.pCur );
881 template <typename Q, typename Compare, typename Func>
882 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp, Func f )
885 return erase_at( refHead, val, cmp, f, pos );
888 template <typename Q, typename Compare>
889 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp )
892 return erase_at( refHead, val, cmp, [](value_type const&){}, pos );
895 template <typename Q, typename Compare >
896 value_type * extract_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
900 assert( gc::is_locked() ) ; // RCU must be locked!!!
903 if ( !search( refHead, val, pos, cmp ) )
905 if ( !unlink_node( pos )) {
911 return node_traits::to_value_ptr( pos.pCur );
915 template <typename Q, typename Compare, typename Func>
916 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f, bool bLock = true ) const
921 if ( search( refHead, val, pos, cmp ) ) {
922 assert( pos.pCur != nullptr );
923 f( *node_traits::to_value_ptr( *pos.pCur ), val );
929 template <typename Q, typename Compare>
930 bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
933 return find_at_( refHead, val, cmp ) != end();
936 template <typename Q, typename Compare>
937 value_type * get_at( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
939 value_type * pFound = nullptr;
940 return find_at( refHead, val, cmp,
941 [&pFound](value_type& found, Q const& ) { pFound = &found; } )
945 template <typename Q, typename Compare>
946 const_iterator find_at_( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
948 assert( gc::is_locked() );
951 if ( search( refHead, val, pos, cmp ) ) {
952 assert( pos.pCur != nullptr );
953 return const_iterator( pos.pCur );
963 template <typename Q, typename Compare>
964 bool search( atomic_node_ptr& refHead, const Q& val, position& pos, Compare cmp ) const
966 // RCU lock should be locked!!!
967 assert( gc::is_locked() );
969 atomic_node_ptr * pPrev;
970 marked_node_ptr pNext;
971 marked_node_ptr pCur;
977 pCur = pPrev->load(memory_model::memory_order_acquire);
988 pNext = pCur->m_pNext.load(memory_model::memory_order_acquire);
990 if ( pPrev->load(memory_model::memory_order_relaxed) != pCur
991 || pNext != pCur->m_pNext.load(memory_model::memory_order_relaxed)
992 || pNext.bits() != 0 ) // pNext contains deletion mark for pCur
994 // if pCur is marked as deleted (pNext.bits() != 0)
995 // we wait for physical removal.
996 // Helping technique is not suitable for RCU since it requires
997 // that the RCU should be in unlocking state.
1002 assert( pCur.ptr() != nullptr );
1003 int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr() ), val );
1006 pos.pCur = pCur.ptr();
1007 pos.pNext = pNext.ptr();
1010 pPrev = &( pCur->m_pNext );
1017 }} // namespace cds::intrusive
1019 #endif // #ifndef CDSLIB_INTRUSIVE_MICHAEL_LIST_NOGC_H