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_MICHAEL_LIST_RCU_H
32 #define CDSLIB_INTRUSIVE_MICHAEL_LIST_RCU_H
34 #include <cds/intrusive/details/michael_list_base.h>
35 #include <cds/urcu/details/check_deadlock.h>
36 #include <cds/details/binary_functor_wrapper.h>
37 #include <cds/details/make_const_type.h>
38 #include <cds/urcu/exempt_ptr.h>
39 #include <cds/urcu/raw_ptr.h>
40 #include <cds/intrusive/details/raw_ptr_disposer.h>
42 namespace cds { namespace intrusive {
45 namespace michael_list {
47 /// Node specialization for uRCU
48 template <class RCU, typename Tag>
49 struct node< cds::urcu::gc< RCU >, Tag >
51 typedef cds::urcu::gc< RCU > gc; ///< Garbage collector
52 typedef Tag tag; ///< tag
54 typedef cds::details::marked_ptr<node, 3> marked_ptr; ///< marked pointer
55 typedef typename gc::template atomic_marked_ptr<marked_ptr> atomic_marked_ptr; ///< atomic marked pointer specific for GC
57 atomic_marked_ptr m_pNext; ///< pointer to the next node in the container
58 node * m_pDelChain; ///< Deleted node chain (local for a thread)
60 CDS_CONSTEXPR node() CDS_NOEXCEPT
62 , m_pDelChain( nullptr )
65 } // namespace michael_list
68 /// Michael's lock-free ordered single-linked list (template specialization for \ref cds_urcu_desc "RCU")
69 /** @ingroup cds_intrusive_list
70 \anchor cds_intrusive_MichaelList_rcu
72 Usually, ordered single-linked list is used as a building block for the hash table implementation.
73 The complexity of searching is <tt>O(N)</tt>.
76 - \p RCU - one of \ref cds_urcu_gc "RCU type"
77 - \p T - type to be stored in the list; the type \p T should be based on (or has a member of type)
78 cds::intrusive::micheal_list::node
79 - \p Traits - type traits. See \p michael_list::traits for explanation. It is possible to declare option-based
80 list with \p cds::intrusive::michael_list::make_traits metafunction,
81 see \ref cds_intrusive_MichaelList_hp "here" for explanations.
84 Before including <tt><cds/intrusive/michael_list_rcu.h></tt> you should include appropriate RCU header file,
85 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
86 For example, for \ref cds_urcu_general_buffered_gc "general-purpose buffered RCU" you should include:
88 #include <cds/urcu/general_buffered.h>
89 #include <cds/intrusive/michael_list_rcu.h>
91 // Now, you can declare Michael's list for type Foo and default traits:
92 typedef cds::intrusive::MichaelList<cds::urcu::gc< cds::urcu::general_buffered<> >, Foo > rcu_michael_list;
95 template < typename RCU, typename T,
96 #ifdef CDS_DOXYGEN_INVOKED
97 class Traits = michael_list::traits
102 class MichaelList<cds::urcu::gc<RCU>, T, Traits>
105 typedef T value_type; ///< type of value stored in the list
106 typedef Traits traits; ///< Traits template parameter
108 typedef typename traits::hook hook; ///< hook type
109 typedef typename hook::node_type node_type; ///< node type
111 # ifdef CDS_DOXYGEN_INVOKED
112 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
114 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
117 typedef typename traits::disposer disposer; ///< disposer used
118 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
119 typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
121 typedef cds::urcu::gc<RCU> gc; ///< RCU schema
122 typedef typename traits::back_off back_off; ///< back-off strategy
123 typedef typename traits::item_counter item_counter; ///< Item counting policy used
124 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
125 typedef typename traits::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
126 typedef typename traits::stat stat; ///< Internal statistics
128 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
129 static CDS_CONSTEXPR const bool c_bExtractLockExternal = false; ///< Group of \p extract_xxx functions do not require external locking
132 // Rebind traits (split-list support)
133 template <typename... Options>
134 struct rebind_traits {
138 , typename cds::opt::make_options< traits, Options...>::type
144 typedef typename node_type::marked_ptr marked_node_ptr; ///< Marked node pointer
145 typedef typename node_type::atomic_marked_ptr atomic_node_ptr; ///< Atomic node pointer
146 typedef atomic_node_ptr auxiliary_head; ///< Auxiliary head type (for split-list support)
148 atomic_node_ptr m_pHead; ///< Head pointer
149 item_counter m_ItemCounter; ///< Item counter
150 stat m_Stat; ///< Internal statistics
160 typedef cds::urcu::details::check_deadlock_policy< gc, rcu_check_deadlock> check_deadlock_policy;
162 static void clear_links( node_type * pNode )
164 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_release );
165 pNode->m_pDelChain = nullptr;
168 struct clear_and_dispose {
169 void operator()( value_type * p )
171 assert( p != nullptr );
172 clear_links( node_traits::to_node_ptr(p));
177 static void dispose_node( node_type * pNode )
180 assert( !gc::is_locked() );
182 gc::template retire_ptr<clear_and_dispose>( node_traits::to_value_ptr( *pNode ) );
185 static void dispose_chain( node_type * pChain )
188 assert( !gc::is_locked() );
190 auto f = [&pChain]() -> cds::urcu::retired_ptr {
191 node_type * p = pChain;
193 pChain = p->m_pDelChain;
194 return cds::urcu::make_retired_ptr<clear_and_dispose>( node_traits::to_value_ptr( p ));
196 return cds::urcu::make_retired_ptr<clear_and_dispose>( static_cast<value_type *>(nullptr));
198 gc::batch_retire(std::ref(f));
202 /// Position pointer for item search
204 atomic_node_ptr * pPrev ; ///< Previous node
205 node_type * pCur ; ///< Current node
206 node_type * pNext ; ///< Next node
208 atomic_node_ptr& refHead;
209 node_type * pDelChain; ///< Head of deleted node chain
211 position( atomic_node_ptr& head )
213 , pDelChain( nullptr )
218 dispose_chain( pDelChain );
225 using exempt_ptr = cds::urcu::exempt_ptr< gc, value_type, value_type, clear_and_dispose, void >; ///< pointer to extracted node
229 struct chain_disposer {
230 void operator()( node_type * pChain ) const
232 dispose_chain( pChain );
235 typedef cds::intrusive::details::raw_ptr_disposer< gc, node_type, chain_disposer> raw_ptr_disposer;
239 /// Result of \p get(), \p get_with() functions - pointer to the node found
240 typedef cds::urcu::raw_ptr< gc, value_type, raw_ptr_disposer > raw_ptr;
245 bool link_node( node_type * pNode, position& pos )
247 assert( pNode != nullptr );
248 link_checker::is_empty( pNode );
250 marked_node_ptr p( pos.pCur );
251 pNode->m_pNext.store( p, memory_model::memory_order_release );
252 if ( cds_likely( pos.pPrev->compare_exchange_strong( p, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed )))
255 pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
259 static void link_to_remove_chain( position& pos, node_type * pDel )
261 assert( pDel->m_pDelChain == nullptr );
263 pDel->m_pDelChain = pos.pDelChain;
264 pos.pDelChain = pDel;
267 bool unlink_node( position& pos, erase_node_mask nMask )
269 assert(gc::is_locked() );
271 // Mark the node (logical deletion)
272 marked_node_ptr next(pos.pNext, 0);
274 if ( cds_likely( pos.pCur->m_pNext.compare_exchange_strong( next, next | nMask, memory_model::memory_order_release, atomics::memory_order_relaxed ))) {
276 // Try physical removal - fast path
277 marked_node_ptr cur(pos.pCur);
278 if ( cds_likely( pos.pPrev->compare_exchange_strong(cur, marked_node_ptr(pos.pNext), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))) {
279 if ( nMask == erase_mask )
280 link_to_remove_chain( pos, pos.pCur );
284 search( pos.refHead, *node_traits::to_value_ptr( pos.pCur ), pos, key_comparator() );
294 template <bool IsConst>
297 friend class MichaelList;
298 value_type * m_pNode;
303 node_type * p = node_traits::to_node_ptr( *m_pNode )->m_pNext.load(memory_model::memory_order_relaxed).ptr();
304 m_pNode = p ? node_traits::to_value_ptr( p ) : nullptr;
309 explicit iterator_type( node_type * pNode)
312 m_pNode = node_traits::to_value_ptr( *pNode );
316 explicit iterator_type( atomic_node_ptr const& refNode)
318 node_type * pNode = refNode.load(memory_model::memory_order_relaxed).ptr();
319 m_pNode = pNode ? node_traits::to_value_ptr( *pNode ) : nullptr;
323 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
324 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
330 iterator_type( const iterator_type& src )
331 : m_pNode( src.m_pNode )
334 value_ptr operator ->() const
339 value_ref operator *() const
341 assert( m_pNode != nullptr );
346 iterator_type& operator ++()
353 iterator_type operator ++(int)
355 iterator_type i(*this);
360 iterator_type& operator = (const iterator_type& src)
362 m_pNode = src.m_pNode;
367 bool operator ==(iterator_type<C> const& i ) const
369 return m_pNode == i.m_pNode;
372 bool operator !=(iterator_type<C> const& i ) const
374 return m_pNode != i.m_pNode;
380 ///@name Forward iterators (thread-safe only under RCU lock)
384 You may safely use iterators in multi-threaded environment only under RCU lock.
385 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
387 typedef iterator_type<false> iterator;
389 /// Const forward iterator
390 typedef iterator_type<true> const_iterator;
392 /// Returns a forward iterator addressing the first element in a list
394 For empty list \code begin() == end() \endcode
398 return iterator( m_pHead );
401 /// Returns an iterator that addresses the location succeeding the last element in a list
403 Do not use the value returned by <tt>end</tt> function to access any item.
404 Internally, <tt>end</tt> returning value equals to \p nullptr.
406 The returned value can be used only to control reaching the end of the list.
407 For empty list \code begin() == end() \endcode
414 /// Returns a forward const iterator addressing the first element in a list
415 const_iterator begin() const
417 return const_iterator(m_pHead );
419 /// Returns a forward const iterator addressing the first element in a list
420 const_iterator cbegin() const
422 return const_iterator(m_pHead );
425 /// Returns an const iterator that addresses the location succeeding the last element in a list
426 const_iterator end() const
428 return const_iterator();
430 /// Returns an const iterator that addresses the location succeeding the last element in a list
431 const_iterator cend() const
433 return const_iterator();
438 /// Default constructor initializes empty list
442 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
446 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
447 explicit MichaelList( Stat& st )
461 The function inserts \p val in the list if the list does not contain
462 an item with key equal to \p val.
464 The function makes RCU lock internally.
466 Returns \p true if \p val is linked into the list, \p false otherwise.
468 bool insert( value_type& val )
470 return insert_at( m_pHead, val );
475 This function is intended for derived non-intrusive containers.
477 The function allows to split new item creating into two part:
478 - create item with key only
479 - insert new item into the list
480 - if inserting is success, calls \p f functor to initialize value-field of \p val.
482 The functor signature is:
484 void func( value_type& val );
486 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
487 \p val no any other changes could be made on this list's item by concurrent threads.
488 The user-defined functor is called only if the inserting is success.
490 The function makes RCU lock internally.
492 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
494 template <typename Func>
495 bool insert( value_type& val, Func f )
497 return insert_at( m_pHead, val, f );
502 The operation performs inserting or changing data with lock-free manner.
504 If the item \p val not found in the list, then \p val is inserted into the list
505 iff \p bAllowInsert is \p true.
506 Otherwise, the functor \p func is called with item found.
507 The functor signature is:
510 void operator()( bool bNew, value_type& item, value_type& val );
514 - \p bNew - \p true if the item has been inserted, \p false otherwise
515 - \p item - item of the list
516 - \p val - argument \p val passed into the \p update() function
517 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
518 refer to the same thing.
520 The functor may change non-key fields of the \p item; however, \p func must guarantee
521 that during changing no any other modifications could be made on this item by concurrent threads.
523 Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successful,
524 \p second is \p true if new item has been added or \p false if the item with \p key
525 already is in the list.
527 The function makes RCU lock internally.
529 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
531 template <typename Func>
532 std::pair<bool, bool> update( value_type& val, Func func, bool bAllowInsert = true )
534 return update_at( m_pHead, val, func, bAllowInsert );
537 template <typename Func>
538 CDS_DEPRECATED("ensure() is deprecated, use update()")
539 std::pair<bool, bool> ensure( value_type& val, Func func )
541 return update( val, func, true );
545 /// Unlinks the item \p val from the list
547 The function searches the item \p val in the list and unlink it from the list
548 if it is found and it is equal to \p val.
550 Difference between \p erase() and \p %unlink() functions: \p %erase() finds <i>a key</i>
551 and deletes the item found. \p %unlink() finds an item by key and deletes it
552 only if \p val is an item of that list, i.e. the pointer to the item found
553 is equal to <tt> &val </tt>.
555 The function returns \p true if success and \p false otherwise.
557 RCU \p synchronize method can be called.
558 Note that depending on RCU type used the \ref disposer call can be deferred.
560 \p disposer specified in \p Traits is called for unlinked item.
562 The function can throw cds::urcu::rcu_deadlock exception if deadlock is encountered and
563 deadlock checking policy is opt::v::rcu_throw_deadlock.
565 bool unlink( value_type& val )
567 return unlink_at( m_pHead, val );
570 /// Deletes the item from the list
572 The function searches an item with key equal to \p key in the list,
573 unlinks it from the list, and returns \p true.
574 If the item with the key equal to \p key is not found the function return \p false.
576 RCU \p synchronize method can be called.
577 Note that depending on RCU type used the \ref disposer call can be deferred.
579 \p disposer specified in \p Traits is called for deleted item.
581 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
582 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
584 template <typename Q>
585 bool erase( Q const& key )
587 return erase_at( m_pHead, key, key_comparator() );
590 /// Deletes the item from the list using \p pred predicate for searching
592 The function is an analog of \p erase(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 \p disposer specified in \p Traits is called for deleted item.
599 template <typename Q, typename Less>
600 bool erase_with( Q const& key, Less pred )
603 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() );
606 /// Deletes the item from the list
608 The function searches an item with key equal to \p key in the list,
609 call \p func functor with item found, unlinks it from the list, and returns \p true.
610 The \p Func interface is
613 void operator()( value_type const& item );
617 If the item with the key equal to \p key is not found the function return \p false.
619 RCU \p synchronize method can be called.
620 Note that depending on RCU type used the \ref disposer call can be deferred.
622 \p disposer specified in \p Traits is called for deleted item.
624 The function can throw \ref cds_urcu_rcu_deadlock "cds::urcu::rcu_deadlock" exception if a deadlock is detected and
625 the deadlock checking policy is \p opt::v::rcu_throw_deadlock.
627 template <typename Q, typename Func>
628 bool erase( Q const& key, Func func )
630 return erase_at( m_pHead, key, key_comparator(), func );
633 /// Deletes the item from the list using \p pred predicate for searching
635 The function is an analog of \p erase(Q const&, Func)
636 but \p pred is used for key comparing.
637 \p Less functor has the interface like \p std::less.
638 \p pred must imply the same element order as the comparator used for building the list.
640 \p disposer specified in \p Traits is called for deleted item.
642 template <typename Q, typename Less, typename Func>
643 bool erase_with( Q const& key, Less pred, Func func )
646 return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), func );
649 /// Extracts an item from the list
651 The function searches an item with key equal to \p key in the list,
652 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
653 If \p key is not found the function returns an empty \p exempt_ptr.
655 @note The function does NOT dispose the item found. It just unlinks the item from the list
656 and returns a pointer to item found.
657 You shouldn't lock RCU for current thread before calling this function, and you should manually release
658 the returned exempt pointer before reusing it.
661 #include <cds/urcu/general_buffered.h>
662 #include <cds/intrusive/michael_list_rcu.h>
664 typedef cds::urcu::gc< general_buffered<> > rcu;
665 typedef cds::intrusive::MichaelList< rcu, Foo > rcu_michael_list;
667 rcu_michael_list theList;
670 rcu_michael_list::exempt_ptr p1;
672 // The RCU should NOT be locked when extract() is called!
673 assert( !rcu::is_locked() );
675 // You can call extract() function
676 p1 = theList.extract( 10 );
678 // do something with p1
682 // We may safely release p1 here
683 // release() passes the pointer to RCU reclamation cycle:
684 // it invokes RCU retire_ptr function with the disposer you provided for the list.
688 template <typename Q>
689 exempt_ptr extract( Q const& key )
691 return exempt_ptr( extract_at( m_pHead, key, key_comparator() ));
694 /// Extracts an item from the list using \p pred predicate for searching
696 This function is the analog for \p extract(Q const&)
698 The \p pred is a predicate used for key comparing.
699 \p Less has the interface like \p std::less.
700 \p pred must imply the same element order as \ref key_comparator.
702 template <typename Q, typename Less>
703 exempt_ptr extract_with( Q const& key, Less pred )
706 return exempt_ptr( extract_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() ));
709 /// Find the key \p val
711 The function searches the item with key equal to \p key
712 and calls the functor \p f for item found.
713 The interface of \p Func functor is:
716 void operator()( value_type& item, Q& key );
719 where \p item is the item found, \p key is the <tt>find</tt> function argument.
721 The functor can change non-key fields of \p item.
722 The function \p find does not serialize simultaneous access to the list \p item. If such access is
723 possible you must provide your own synchronization schema to exclude unsafe item modifications.
725 The function makes RCU lock internally.
727 The function returns \p true if \p val is found, \p false otherwise.
729 template <typename Q, typename Func>
730 bool find( Q& key, Func f )
732 return find_at( m_pHead, key, key_comparator(), f );
735 template <typename Q, typename Func>
736 bool find( Q const& key, Func f )
738 return find_at( m_pHead, key, key_comparator(), f );
742 /// Finds \p key using \p pred predicate for searching
744 The function is an analog of \p find(Q&, Func)
745 but \p pred is used for key comparing.
746 \p Less functor has the interface like \p std::less.
747 \p pred must imply the same element order as the comparator used for building the list.
749 template <typename Q, typename Less, typename Func>
750 bool find_with( Q& key, Less pred, Func f )
753 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
756 template <typename Q, typename Less, typename Func>
757 bool find_with( Q const& key, Less pred, Func f )
760 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
764 /// Checks whether the list contains \p key
766 The function searches the item with key equal to \p key
767 and returns \p true if it is found, and \p false otherwise.
769 template <typename Q>
770 bool contains( Q const& key )
772 return find_at( m_pHead, key, key_comparator() );
775 template <typename Q>
776 CDS_DEPRECATED("deprecated, use contains()")
777 bool find( Q const& key )
779 return contains( key );
783 /// Checks whether the map contains \p key using \p pred predicate for searching
785 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
786 \p Less functor has the interface like \p std::less.
787 \p Less must imply the same element order as the comparator used for building the list.
789 template <typename Q, typename Less>
790 bool contains( Q const& key, Less pred )
793 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>() );
796 template <typename Q, typename Less>
797 CDS_DEPRECATED("deprecated, use contains()")
798 bool find_with( Q const& key, Less pred )
800 return contains( key, pred );
804 /// Finds \p key and return the item found
805 /** \anchor cds_intrusive_MichaelList_rcu_get
806 The function searches the item with key equal to \p key and returns the pointer to item found.
807 If \p key is not found it returns empty \p raw_ptr object.
809 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
811 RCU should be locked before call of this function.
812 Returned item is valid only while RCU is locked:
814 typedef cds::intrusive::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
817 typename ord_list::raw_ptr rp;
820 ord_list::rcu_lock lock;
822 rp = theList.get( 5 );
827 // Unlock RCU by rcu_lock destructor
828 // Node owned by rp can be retired by disposer at any time after RCU has been unlocked
830 // You can manually release rp after RCU-locked section
834 template <typename Q>
835 raw_ptr get( Q const& key )
837 return get_at( m_pHead, key, key_comparator());
840 /// Finds \p key and return the item found
842 The function is an analog of \ref cds_intrusive_MichaelList_rcu_get "get(Q const&)"
843 but \p pred is used for comparing the keys.
845 \p Less functor has the semantics like \p std::less but should take arguments of type \p value_type and \p Q
847 \p pred must imply the same element order as the comparator used for building the list.
849 template <typename Q, typename Less>
850 raw_ptr get_with( Q const& key, Less pred )
853 return get_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
856 /// Clears the list using default disposer
858 The function clears the list using default (provided by \p Traits class template argument) disposer functor.
860 RCU \p synchronize method can be called.
861 Note that depending on RCU type used the \ref disposer invocation can be deferred.
863 The function can throw \p cds::urcu::rcu_deadlock exception if a deadlock is encountered and
864 deadlock checking policy is \p opt::v::rcu_throw_deadlock.
869 check_deadlock_policy::check();
871 marked_node_ptr pHead;
875 pHead = m_pHead.load(memory_model::memory_order_acquire);
878 marked_node_ptr pNext( pHead->m_pNext.load(memory_model::memory_order_relaxed) );
879 if ( cds_unlikely( !pHead->m_pNext.compare_exchange_weak( pNext, pNext | 1, memory_model::memory_order_acquire, memory_model::memory_order_relaxed )))
881 if ( cds_unlikely( !m_pHead.compare_exchange_weak( pHead, marked_node_ptr(pNext.ptr()), memory_model::memory_order_release, memory_model::memory_order_relaxed )))
886 dispose_node( pHead.ptr() );
891 /// Check if the list is empty
894 return m_pHead.load( memory_model::memory_order_relaxed ).all() == nullptr;
897 /// Returns list's item count
899 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
900 this function always returns 0.
902 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
903 is empty. To check list emptyness use \p empty() method.
907 return m_ItemCounter.value();
910 /// Returns const reference to internal statistics
911 stat const& statistics() const
917 // split-list support
918 bool insert_aux_node( node_type * pNode )
920 return insert_aux_node( m_pHead, pNode );
923 // split-list support
924 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
926 assert( pNode != nullptr );
928 // Hack: convert node_type to value_type.
929 // In principle, auxiliary node can be non-reducible to value_type
930 // We assume that comparator can correctly distinguish between aux and regular node.
931 return insert_at( refHead, *node_traits::to_value_ptr( pNode ) );
934 bool insert_at( atomic_node_ptr& refHead, value_type& val )
936 position pos( refHead );
939 return insert_at_locked( pos, val );
943 template <typename Func>
944 bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
946 position pos( refHead );
951 if ( search( refHead, val, pos, key_comparator())) {
952 m_Stat.onInsertFailed();
956 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
959 m_Stat.onInsertSuccess();
964 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
965 m_Stat.onInsertRetry();
971 iterator insert_at_( atomic_node_ptr& refHead, value_type& val )
974 if ( insert_at_locked( refHead, val ))
975 return iterator( node_traits::to_node_ptr( val ));
979 template <typename Func>
980 std::pair<iterator, bool> update_at_( atomic_node_ptr& refHead, value_type& val, Func func, bool bInsert )
982 position pos( refHead );
985 return update_at_locked( pos, val, func, bInsert );
989 template <typename Func>
990 std::pair<bool, bool> update_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bInsert )
992 position pos( refHead );
995 std::pair<iterator, bool> ret = update_at_locked( pos, val, func, bInsert );
996 return std::make_pair( ret.first != end(), ret.second );
1000 bool unlink_at( atomic_node_ptr& refHead, value_type& val )
1002 position pos( refHead );
1004 check_deadlock_policy::check();
1009 if ( !search( refHead, val, pos, key_comparator() ) || node_traits::to_value_ptr( *pos.pCur ) != &val ) {
1010 m_Stat.onEraseFailed();
1013 if ( !unlink_node( pos, erase_mask )) {
1015 m_Stat.onEraseRetry();
1021 m_Stat.onEraseSuccess();
1026 template <typename Q, typename Compare, typename Func>
1027 bool erase_at( position& pos, Q const& val, Compare cmp, Func f )
1030 check_deadlock_policy::check();
1036 if ( !search( pos.refHead, val, pos, cmp ) ) {
1037 m_Stat.onEraseFailed();
1041 // store pCur since it may be changed by unlink_node() slow path
1043 if ( !unlink_node( pos, erase_mask )) {
1045 m_Stat.onEraseRetry();
1050 f( *node_traits::to_value_ptr( pDel ) );
1052 m_Stat.onEraseSuccess();
1057 template <typename Q, typename Compare, typename Func>
1058 bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp, Func f )
1060 position pos( refHead );
1061 return erase_at( pos, val, cmp, f );
1064 template <typename Q, typename Compare>
1065 bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp )
1067 position pos( refHead );
1068 return erase_at( pos, val, cmp, [](value_type const&){} );
1071 template <typename Q, typename Compare >
1072 value_type * extract_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1074 position pos( refHead );
1076 assert( !gc::is_locked() ) ; // RCU must not be locked!!!
1078 node_type * pExtracted;
1082 if ( !search( refHead, val, pos, cmp )) {
1083 m_Stat.onEraseFailed();
1087 // store pCur since it may be changed by unlink_node() slow path
1088 pExtracted = pos.pCur;
1089 if ( !unlink_node( pos, extract_mask )) {
1091 m_Stat.onEraseRetry();
1096 value_type * pRet = node_traits::to_value_ptr( pExtracted );
1097 assert( pExtracted->m_pDelChain == nullptr );
1098 m_Stat.onEraseSuccess();
1104 template <typename Q, typename Compare, typename Func>
1105 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f )
1107 position pos( refHead );
1111 if ( search( refHead, val, pos, cmp ) ) {
1112 assert( pos.pCur != nullptr );
1113 f( *node_traits::to_value_ptr( *pos.pCur ), val );
1114 m_Stat.onFindSuccess();
1119 m_Stat.onFindFailed();
1123 template <typename Q, typename Compare>
1124 bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1126 position pos( refHead );
1129 return find_at_locked( pos, val, cmp ) != cend();
1133 template <typename Q, typename Compare>
1134 raw_ptr get_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
1136 // RCU should be locked!
1137 assert(gc::is_locked() );
1139 position pos( refHead );
1141 if ( search( refHead, val, pos, cmp )) {
1142 m_Stat.onFindSuccess();
1143 return raw_ptr( node_traits::to_value_ptr( pos.pCur ), raw_ptr_disposer( pos ));
1146 m_Stat.onFindFailed();
1147 return raw_ptr( raw_ptr_disposer( pos ));
1154 template <typename Q, typename Compare>
1155 bool search( atomic_node_ptr& refHead, const Q& val, position& pos, Compare cmp )
1157 // RCU lock should be locked!!!
1158 assert( gc::is_locked() );
1160 atomic_node_ptr * pPrev;
1161 marked_node_ptr pNext;
1162 marked_node_ptr pCur;
1168 pCur = pPrev->load(memory_model::memory_order_acquire);
1172 if ( !pCur.ptr() ) {
1175 pos.pNext = nullptr;
1179 pNext = pCur->m_pNext.load(memory_model::memory_order_acquire);
1181 if ( cds_unlikely( pPrev->load(memory_model::memory_order_acquire) != pCur
1182 || pNext != pCur->m_pNext.load(memory_model::memory_order_acquire )))
1188 if ( pNext.bits() ) {
1189 // pCur is marked as deleted. Try to unlink it from the list
1190 if ( cds_likely( pPrev->compare_exchange_weak( pCur, marked_node_ptr( pNext.ptr() ), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))) {
1191 if ( pNext.bits() == erase_mask )
1192 link_to_remove_chain( pos, pCur.ptr() );
1193 m_Stat.onHelpingSuccess();
1196 m_Stat.onHelpingFailed();
1200 assert( pCur.ptr() != nullptr );
1201 int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr() ), val );
1204 pos.pCur = pCur.ptr();
1205 pos.pNext = pNext.ptr();
1208 pPrev = &( pCur->m_pNext );
1216 bool insert_at_locked( position& pos, value_type& val )
1218 // RCU lock should be locked!!!
1219 assert( gc::is_locked() );
1222 if ( search( pos.refHead, val, pos, key_comparator() )) {
1223 m_Stat.onInsertFailed();
1227 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
1229 m_Stat.onInsertSuccess();
1234 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
1235 m_Stat.onInsertRetry();
1239 template <typename Func>
1240 std::pair<iterator, bool> update_at_locked( position& pos, value_type& val, Func func, bool bInsert )
1242 // RCU should be locked!!!
1243 assert( gc::is_locked() );
1246 if ( search( pos.refHead, val, pos, key_comparator() ) ) {
1247 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur ) ) == 0 );
1249 func( false, *node_traits::to_value_ptr( *pos.pCur ), val );
1250 m_Stat.onUpdateExisting();
1251 return std::make_pair( iterator( pos.pCur ), false );
1255 m_Stat.onUpdateFailed();
1256 return std::make_pair( end(), false );
1259 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
1261 func( true, val , val );
1262 m_Stat.onUpdateNew();
1263 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
1266 // clear the next field
1267 node_traits::to_node_ptr( val )->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
1268 m_Stat.onUpdateRetry();
1273 template <typename Q, typename Compare>
1274 const_iterator find_at_locked( position& pos, Q const& val, Compare cmp )
1276 assert( gc::is_locked() );
1278 if ( search( pos.refHead, val, pos, cmp ) ) {
1279 assert( pos.pCur != nullptr );
1280 m_Stat.onFindSuccess();
1281 return const_iterator( pos.pCur );
1284 m_Stat.onFindFailed();
1290 }} // namespace cds::intrusive
1292 #endif // #ifndef CDSLIB_INTRUSIVE_MICHAEL_LIST_NOGC_H