3 #ifndef __CDS_INTRUSIVE_MICHAEL_LIST_RCU_H
4 #define __CDS_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 typedef cds::urcu::exempt_ptr< gc, value_type, value_type, clear_and_dispose, void > exempt_ptr ; ///< 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_relaxed );
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_acquire, 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_release, atomics::memory_order_relaxed ))
154 CDS_VERIFY( pos.pCur->m_pNext.compare_exchange_strong( next, next ^ 1, memory_model::memory_order_release, 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()
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()
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 template <typename Func>
345 bool insert( value_type& val, Func f )
347 return insert_at( m_pHead, val, f );
350 /// Ensures that the \p item exists in the list
352 The operation performs inserting or changing data with lock-free manner.
354 If the item \p val not found in the list, then \p val is inserted into the list.
355 Otherwise, the functor \p func is called with item found.
356 The functor signature is:
359 void operator()( bool bNew, value_type& item, value_type& val );
363 - \p bNew - \p true if the item has been inserted, \p false otherwise
364 - \p item - item of the list
365 - \p val - argument \p val passed into the \p ensure function
366 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
367 refer to the same thing.
369 The functor may change non-key fields of the \p item; however, \p func must guarantee
370 that during changing no any other modifications could be made on this item by concurrent threads.
372 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
373 \p second is true if new item has been added or \p false if the item with \p key
374 already is in the list.
376 The function makes RCU lock internally.
378 template <typename Func>
379 std::pair<bool, bool> ensure( value_type& val, Func func )
381 return ensure_at( m_pHead, val, func );
384 /// Unlinks the item \p val from the list
386 The function searches the item \p val in the list and unlink it from the list
387 if it is found and it is equal to \p val.
389 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
390 and deletes the item found. \p unlink finds an item by key and deletes it
391 only if \p val is an item of that list, i.e. the pointer to the item found
392 is equal to <tt> &val </tt>.
394 The function returns \p true if success and \p false otherwise.
396 RCU \p synchronize method can be called.
397 Note that depending on RCU type used the \ref disposer call can be deferred.
399 The function can throw cds::urcu::rcu_deadlock exception if deadlock is encountered and
400 deadlock checking policy is opt::v::rcu_throw_deadlock.
402 bool unlink( value_type& val )
404 return unlink_at( m_pHead, val );
407 /// Deletes the item from the list
408 /** \anchor cds_intrusive_MichaelList_rcu_erase_val
409 The function searches an item with key equal to \p key in the list,
410 unlinks it from the list, and returns \p true.
411 If the item with the key equal to \p key is not found the function return \p false.
413 RCU \p synchronize method can be called.
414 Note that depending on RCU type used the \ref disposer call can be deferred.
416 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
417 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
419 template <typename Q>
420 bool erase( Q const& key )
422 return erase_at( m_pHead, key, key_comparator() );
425 /// Deletes the item from the list using \p pred predicate for searching
427 The function is an analog of \ref cds_intrusive_MichaelList_rcu_erase_val "erase(Q const&)"
428 but \p pred is used for key comparing.
429 \p Less functor has the interface like \p std::less.
430 \p pred must imply the same element order as the comparator used for building the list.
432 template <typename Q, typename Less>
433 bool erase_with( Q const& key, Less pred )
435 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() );
438 /// Deletes the item from the list
439 /** \anchor cds_intrusive_MichaelList_rcu_erase_func
440 The function searches an item with key equal to \p key in the list,
441 call \p func functor with item found, unlinks it from the list, and returns \p true.
442 The \p Func interface is
445 void operator()( value_type const& item );
449 If the item with the key equal to \p key is not found the function return \p false.
451 RCU \p synchronize method can be called.
452 Note that depending on RCU type used the \ref disposer call can be deferred.
454 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
455 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
457 template <typename Q, typename Func>
458 bool erase( Q const& key, Func func )
460 return erase_at( m_pHead, key, key_comparator(), func );
463 /// Deletes the item from the list using \p pred predicate for searching
465 The function is an analog of \ref cds_intrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
466 but \p pred is used for key comparing.
467 \p Less functor has the interface like \p std::less.
468 \p pred must imply the same element order as the comparator used for building the list.
470 template <typename Q, typename Less, typename Func>
471 bool erase_with( Q const& key, Less pred, Func func )
473 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), func );
476 /// Extracts an item from the list
478 @anchor cds_intrusive_MichaelList_rcu_extract
479 The function searches an item with key equal to \p key in the list,
480 unlinks it from the list, and returns pointer to an item found in \p dest parameter.
481 If \p key is not found the function returns \p false, \p dest is empty.
483 @note The function does NOT call RCU read-side lock or synchronization,
484 and does NOT dispose the item found. It just unlinks the item from the list
485 and returns a pointer to item found.
486 You should lock RCU before calling this function, and you should manually release
487 \p dest exempt pointer outside the RCU lock before reusing the pointer.
490 #include <cds/urcu/general_buffered.h>
491 #include <cds/intrusive/michael_list_rcu.h>
493 typedef cds::urcu::gc< general_buffered<> > rcu;
494 typedef cds::intrusive::MichaelList< rcu, Foo > rcu_michael_list;
496 rcu_michael_list theList;
499 rcu_michael_list::exempt_ptr p1;
501 // first, we should lock RCU
504 // Now, you can apply extract function
505 // Note that you must not delete the item found inside the RCU lock
506 if ( theList.extract( p1, 10 )) {
507 // do something with p1
512 // We may safely release p1 here
513 // release() passes the pointer to RCU reclamation cycle:
514 // it invokes RCU retire_ptr function with the disposer you provided for the list.
518 template <typename Q>
519 bool extract( exempt_ptr& dest, Q const& key )
521 dest = extract_at( m_pHead, key, key_comparator() );
522 return !dest.empty();
525 /// Extracts an item from the list using \p pred predicate for searching
527 This function is the analog for \ref cds_intrusive_MichaelList_rcu_extract "extract(exempt_ptr&, Q const&)".
529 The \p pred is a predicate used for key comparing.
530 \p Less has the interface like \p std::less.
531 \p pred must imply the same element order as \ref key_comparator.
533 template <typename Q, typename Less>
534 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
536 dest = extract_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() );
537 return !dest.empty();
540 /// Find the key \p val
541 /** \anchor cds_intrusive_MichaelList_rcu_find_func
542 The function searches the item with key equal to \p key
543 and calls the functor \p f for item found.
544 The interface of \p Func functor is:
547 void operator()( value_type& item, Q& key );
550 where \p item is the item found, \p key is the <tt>find</tt> function argument.
552 The functor can change non-key fields of \p item.
553 The function \p find does not serialize simultaneous access to the list \p item. If such access is
554 possible you must provide your own synchronization schema to exclude unsafe item modifications.
556 The function makes RCU lock internally.
558 The function returns \p true if \p val is found, \p false otherwise.
560 template <typename Q, typename Func>
561 bool find( Q& key, Func f ) const
563 return find_at( const_cast<atomic_node_ptr&>(m_pHead), key, key_comparator(), f );
566 /// Finds \p key using \p pred predicate for searching
568 The function is an analog of \ref cds_intrusive_MichaelList_rcu_find_func "find(Q&, Func)"
569 but \p pred is used for key comparing.
570 \p Less functor has the interface like \p std::less.
571 \p pred must imply the same element order as the comparator used for building the list.
573 template <typename Q, typename Less, typename Func>
574 bool find_with( Q& key, Less pred, Func f ) const
576 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>(), f );
580 /** \anchor cds_intrusive_MichaelList_rcu_find_val
581 The function searches the item with key equal to \p key
582 and returns \p true if \p val found or \p false otherwise.
584 template <typename Q>
585 bool find( Q const& key ) const
587 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, key_comparator() );
590 /// Finds \p key using \p pred predicate for searching
592 The function is an analog of \ref cds_intrusive_MichaelList_rcu_find_val "find(Q const&)"
593 but \p pred is used for key comparing.
594 \p Less functor has the interface like \p std::less.
595 \p pred must imply the same element order as the comparator used for building the list.
597 template <typename Q, typename Less>
598 bool find_with( Q const& key, Less pred ) const
600 return find_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>() );
603 /// Finds \p key and return the item found
604 /** \anchor cds_intrusive_MichaelList_rcu_get
605 The function searches the item with key equal to \p key and returns the pointer to item found.
606 If \p key is not found it returns \p nullptr.
608 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
610 RCU should be locked before call of this function.
611 Returned item is valid only while RCU is locked:
613 typedef cds::intrusive::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
618 ord_list::rcu_lock lock;
620 foo * pVal = theList.get( 5 );
625 // Unlock RCU by rcu_lock destructor
626 // pVal can be retired by disposer at any time after RCU has been unlocked
630 template <typename Q>
631 value_type * get( Q const& key ) const
633 return get_at( const_cast<atomic_node_ptr&>( m_pHead ), key, key_comparator());
636 /// Finds \p key and return the item found
638 The function is an analog of \ref cds_intrusive_MichaelList_rcu_get "get(Q const&)"
639 but \p pred is used for comparing the keys.
641 \p Less functor has the semantics like \p std::less but should take arguments of type \p value_type and \p Q
643 \p pred must imply the same element order as the comparator used for building the list.
645 template <typename Q, typename Less>
646 value_type * get_with( Q const& key, Less pred ) const
648 return get_at( const_cast<atomic_node_ptr&>( m_pHead ), key, cds::opt::details::make_comparator_from_less<Less>());
651 /// Clears the list using default disposer
653 The function clears the list using default (provided by \p Traits class template argument) disposer functor.
655 RCU \p synchronize method can be called.
656 Note that depending on RCU type used the \ref disposer invocation can be deferred.
658 The function can throw cds::urcu::rcu_deadlock exception if an deadlock is encountered and
659 deadlock checking policy is opt::v::rcu_throw_deadlock.
664 check_deadlock_policy::check();
666 marked_node_ptr pHead;
670 pHead = m_pHead.load(memory_model::memory_order_consume);
673 marked_node_ptr pNext( pHead->m_pNext.load(memory_model::memory_order_relaxed) );
674 if ( !pHead->m_pNext.compare_exchange_weak( pNext, pNext | 1, memory_model::memory_order_acquire, memory_model::memory_order_relaxed ))
676 if ( !m_pHead.compare_exchange_weak( pHead, marked_node_ptr(pNext.ptr()), memory_model::memory_order_release, memory_model::memory_order_relaxed ))
681 dispose_node( pHead.ptr() );
686 /// Check if the list is empty
689 return m_pHead.load( memory_model::memory_order_relaxed ).all() == nullptr;
692 /// Returns list's item count
694 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
695 this function always returns 0.
697 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
698 is empty. To check list emptyness use \p empty() method.
702 return m_ItemCounter.value();
707 // split-list support
708 bool insert_aux_node( node_type * pNode )
710 return insert_aux_node( m_pHead, pNode );
713 // split-list support
714 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
716 assert( pNode != nullptr );
718 // Hack: convert node_type to value_type.
719 // In principle, auxiliary node can be non-reducible to value_type
720 // We assume that comparator can correctly distinguish between aux and regular node.
721 return insert_at( refHead, *node_traits::to_value_ptr( pNode ) );
724 bool insert_at( atomic_node_ptr& refHead, value_type& val, bool bLock = true )
726 link_checker::is_empty( node_traits::to_node_ptr( val ) );
731 if ( search( refHead, val, pos, key_comparator() ) )
734 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
740 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
744 template <typename Func>
745 bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
747 link_checker::is_empty( node_traits::to_node_ptr( val ) );
752 if ( search( refHead, val, pos, key_comparator() ) )
755 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
762 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
766 iterator insert_at_( atomic_node_ptr& refHead, value_type& val, bool bLock = true )
769 if ( insert_at( refHead, val, false ))
770 return iterator( node_traits::to_node_ptr( val ));
774 template <typename Func>
775 std::pair<iterator, bool> ensure_at_( atomic_node_ptr& refHead, value_type& val, Func func, bool bLock = true )
781 if ( search( refHead, val, pos, key_comparator() ) ) {
782 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur ) ) == 0 );
784 func( false, *node_traits::to_value_ptr( *pos.pCur ), val );
785 return std::make_pair( iterator( pos.pCur ), false );
788 link_checker::is_empty( node_traits::to_node_ptr( val ) );
790 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
792 func( true, val , val );
793 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
796 // clear the next field
797 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
802 template <typename Func>
803 std::pair<bool, bool> ensure_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bLock = true )
806 std::pair<iterator, bool> ret = ensure_at_( refHead, val, func, false );
807 return std::make_pair( ret.first != end(), ret.second );
810 bool unlink_at( atomic_node_ptr& refHead, value_type& val )
814 check_deadlock_policy::check();
819 if ( !search( refHead, val, pos, key_comparator() ) || node_traits::to_value_ptr( *pos.pCur ) != &val )
821 if ( !unlink_node( pos )) {
828 dispose_node( pos.pCur );
833 template <typename Q, typename Compare, typename Func>
834 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp, Func f, position& pos )
837 check_deadlock_policy::check();
842 if ( !search( refHead, val, pos, cmp ) )
844 if ( !unlink_node( pos )) {
850 f( *node_traits::to_value_ptr( *pos.pCur ) );
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 )
861 return erase_at( refHead, val, cmp, f, pos );
864 template <typename Q, typename Compare>
865 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp )
868 return erase_at( refHead, val, cmp, [](value_type const&){}, pos );
871 template <typename Q, typename Compare >
872 value_type * extract_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
876 assert( gc::is_locked() ) ; // RCU must be locked!!!
879 if ( !search( refHead, val, pos, cmp ) )
881 if ( !unlink_node( pos )) {
887 return node_traits::to_value_ptr( pos.pCur );
891 template <typename Q, typename Compare, typename Func>
892 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f, bool bLock = true ) const
897 if ( search( refHead, val, pos, cmp ) ) {
898 assert( pos.pCur != nullptr );
899 f( *node_traits::to_value_ptr( *pos.pCur ), val );
905 template <typename Q, typename Compare>
906 bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
909 return find_at_( refHead, val, cmp ) != end();
912 template <typename Q, typename Compare>
913 value_type * get_at( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
915 value_type * pFound = nullptr;
916 return find_at( refHead, val, cmp,
917 [&pFound](value_type& found, Q const& ) { pFound = &found; } )
921 template <typename Q, typename Compare>
922 const_iterator find_at_( atomic_node_ptr& refHead, Q const& val, Compare cmp ) const
924 assert( gc::is_locked() );
927 if ( search( refHead, val, pos, cmp ) ) {
928 assert( pos.pCur != nullptr );
929 return const_iterator( pos.pCur );
939 template <typename Q, typename Compare>
940 bool search( atomic_node_ptr& refHead, const Q& val, position& pos, Compare cmp ) const
942 // RCU lock should be locked!!!
943 assert( gc::is_locked() );
945 atomic_node_ptr * pPrev;
946 marked_node_ptr pNext;
947 marked_node_ptr pCur;
953 pCur = pPrev->load(memory_model::memory_order_acquire);
959 pos.pCur = pCur.ptr();
960 pos.pNext = pNext.ptr();
964 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed);
966 if ( pPrev->load(memory_model::memory_order_acquire) != pCur
967 || pNext != pCur->m_pNext.load(memory_model::memory_order_acquire)
968 || pNext.bits() != 0 ) // pNext contains deletion mark for pCur
970 // if pCur is marked as deleted (pNext.bits() != 0)
971 // we wait for physical removal.
972 // Helping technique is not suitable for RCU since it requires
973 // that the RCU should be in unlocking state.
978 assert( pCur.ptr() != nullptr );
979 int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr() ), val );
982 pos.pCur = pCur.ptr();
983 pos.pNext = pNext.ptr();
986 pPrev = &( pCur->m_pNext );
993 }} // namespace cds::intrusive
995 #endif // #ifndef __CDS_INTRUSIVE_MICHAEL_LIST_NOGC_H