3 #ifndef __CDS_CONTAINER_SPLIT_LIST_SET_RCU_H
4 #define __CDS_CONTAINER_SPLIT_LIST_SET_RCU_H
6 #include <cds/intrusive/split_list_rcu.h>
7 #include <cds/container/details/make_split_list_set.h>
8 #include <cds/details/functor_wrapper.h>
10 namespace cds { namespace container {
12 /// Split-ordered list set (template specialization for \ref cds_urcu_desc "RCU")
13 /** @ingroup cds_nonintrusive_set
14 \anchor cds_nonintrusive_SplitListSet_rcu
16 Hash table implementation based on split-ordered list algorithm discovered by Ori Shalev and Nir Shavit, see
17 - [2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"
18 - [2008] Nir Shavit "The Art of Multiprocessor Programming"
20 See intrusive::SplitListSet for a brief description of the split-list algorithm.
23 - \p RCU - one of \ref cds_urcu_gc "RCU type"
24 - \p T - type stored in the split-list. The type must be default- and copy-constructible.
25 - \p Traits - type traits, default is split_list::type_traits. Instead of declaring split_list::type_traits -based
26 struct you may apply option-based notation with split_list::make_traits metafunction.
30 The class supports a forward iterator (\ref iterator and \ref const_iterator).
31 The iteration is ordered.
33 You may iterate over split-list set items only under RCU lock.
34 Only in this case the iterator is thread-safe since
35 while RCU is locked any set's item cannot be reclaimed.
37 The requirement of RCU lock during iterating means that deletion of the elements (i.e. \ref erase)
40 @warning The iterator object cannot be passed between threads
42 \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate
43 all elements in the set: any concurrent deletion can exclude the element
44 pointed by the iterator from the set, and your iteration can be terminated
45 before end of the set. Therefore, such iteration is more suitable for debugging purposes
47 The iterator class supports the following minimalistic interface:
54 iterator( iterator const& s);
56 value_type * operator ->() const;
57 value_type& operator *() const;
60 iterator& operator ++();
63 iterator& operator = (const iterator& src);
65 bool operator ==(iterator const& i ) const;
66 bool operator !=(iterator const& i ) const;
69 Note, the iterator object returned by \ref end, \p cend member functions points to \p nullptr and should not be dereferenced.
73 You should decide what garbage collector you want, and what ordered list you want to use. Split-ordered list
74 is an original data structure based on an ordered list. Suppose, you want construct split-list set based on cds::urcu::general_buffered<> GC
75 and LazyList as ordered list implementation. So, you beginning your program with following include:
77 #include <cds/urcu/general_buffered.h>
78 #include <cds/container/lazy_list_rcu.h>
79 #include <cds/container/split_list_set_rcu.h>
81 namespace cc = cds::container;
83 // The data belonged to split-ordered list
85 int nKey; // key field
86 std::string strValue ; // value field
89 The inclusion order is important:
90 - first, include one of \ref cds_urcu_gc "RCU implementation" (<tt>cds/urcu/general_buffered.h</tt> in our case)
91 - second, include file for ordered-list implementation (for this example, <tt>cds/container/lazy_list_rcu.h</tt>),
92 - then, the header for RCU-based split-list set <tt>cds/container/split_list_set_rcu.h</tt>.
94 Now, you should declare traits for split-list set. The main parts of traits are a hash functor for the set and a comparing functor for ordered list.
95 Note that we define several function in <tt>foo_hash</tt> and <tt>foo_less</tt> functors for different argument types since we want call our \p %SplitListSet
96 object by the key of type <tt>int</tt> and by the value of type <tt>foo</tt>.
98 The second attention: instead of using LazyList in SplitListSet traits we use a tag <tt>cds::contaner::lazy_list_tag</tt> for the lazy list.
99 The split-list requires significant support from underlying ordered list class and it is not good idea to dive you
100 into deep implementation details of split-list and ordered list interrelations. The tag paradigm simplifies split-list interface.
105 size_t operator()( int key ) const { return std::hash( key ) ; }
106 size_t operator()( foo const& item ) const { return std::hash( item.nKey ) ; }
111 bool operator()(int i, foo const& f ) const { return i < f.nKey ; }
112 bool operator()(foo const& f, int i ) const { return f.nKey < i ; }
113 bool operator()(foo const& f1, foo const& f2) const { return f1.nKey < f2.nKey; }
116 // SplitListSet traits
117 struct foo_set_traits: public cc::split_list::type_traits
119 typedef cc::lazy_list_tag ordered_list ; // what type of ordered list we want to use
120 typedef foo_hash hash ; // hash functor for our data stored in split-list set
122 // Type traits for our LazyList class
123 struct ordered_list_traits: public cc::lazy_list::type_traits
125 typedef foo_less less ; // use our foo_less as comparator to order list nodes
130 Now you are ready to declare our set class based on \p %SplitListSet:
132 typedef cc::SplitListSet< cds::urcu::gc<cds::urcu::general_buffered<> >, foo, foo_set_traits > foo_set;
135 You may use the modern option-based declaration instead of classic type-traits-based one:
137 typedef cc:SplitListSet<
138 cds::urcu::gc<cds::urcu::general_buffered<> > // RCU type used
139 ,foo // type of data stored
140 ,cc::split_list::make_traits< // metafunction to build split-list traits
141 cc::split_list::ordered_list<cc::lazy_list_tag> // tag for underlying ordered list implementation
142 ,cc::opt::hash< foo_hash > // hash functor
143 ,cc::split_list::ordered_list_traits< // ordered list traits desired
144 cc::lazy_list::make_traits< // metafunction to build lazy list traits
145 cc::opt::less< foo_less > // less-based compare functor
151 In case of option-based declaration using split_list::make_traits metafunction
152 the struct \p foo_set_traits is not required.
154 Now, the set of type \p foo_set is ready to use in your program.
156 Note that in this example we show only mandatory type_traits parts, optional ones is the default and they are inherited
157 from cds::container::split_list::type_traits.
158 The <b>cds</b> library contains many other options for deep tuning of behavior of the split-list and
159 ordered-list containers.
164 #ifdef CDS_DOXYGEN_INVOKED
165 class Traits = split_list::type_traits
170 class SplitListSet< cds::urcu::gc< RCU >, T, Traits >:
171 #ifdef CDS_DOXYGEN_INVOKED
172 protected intrusive::SplitListSet< cds::urcu::gc< RCU >, typename Traits::ordered_list, Traits >
174 protected details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> >::type
179 typedef details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> > maker;
180 typedef typename maker::type base_class;
184 typedef Traits options ; ///< \p Traits template argument
185 typedef typename maker::gc gc ; ///< Garbage collector
186 typedef typename maker::value_type value_type ; ///< type of value stored in the list
187 typedef typename maker::ordered_list ordered_list ; ///< Underlying ordered list class
188 typedef typename base_class::key_comparator key_comparator; ///< key compare functor
190 /// Hash functor for \ref value_type and all its derivatives that you use
191 typedef typename base_class::hash hash;
192 typedef typename base_class::item_counter item_counter ; ///< Item counter type
194 typedef typename base_class::rcu_lock rcu_lock ; ///< RCU scoped lock
195 /// Group of \p extract_xxx functions require external locking if underlying ordered list requires that
196 static CDS_CONSTEXPR_CONST bool c_bExtractLockExternal = base_class::c_bExtractLockExternal;
200 typedef typename maker::cxx_node_allocator cxx_node_allocator;
201 typedef typename maker::node_type node_type;
205 /// pointer to extracted node
206 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::ordered_list_traits::disposer > exempt_ptr;
211 template <typename Q>
212 static node_type * alloc_node(Q const& v )
214 return cxx_node_allocator().New( v );
217 template <typename Q, typename Func>
218 bool find_( Q& val, Func f )
220 return base_class::find( val, [&f]( node_type& item, Q& val ) { cds::unref(f)(item.m_Value, val) ; } );
223 template <typename Q, typename Less, typename Func>
224 bool find_with_( Q& val, Less pred, Func f )
226 return base_class::find_with( val, typename maker::template predicate_wrapper<Less>::type(),
227 [&f]( node_type& item, Q& val ) { cds::unref(f)(item.m_Value, val) ; } );
231 template <typename... Args>
232 static node_type * alloc_node( Args&&... args )
234 return cxx_node_allocator().MoveNew( std::forward<Args>(args)...);
237 static void free_node( node_type * pNode )
239 cxx_node_allocator().Delete( pNode );
242 struct node_disposer {
243 void operator()( node_type * pNode )
248 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
250 bool insert_node( node_type * pNode )
252 assert( pNode != nullptr );
253 scoped_node_ptr p(pNode);
255 if ( base_class::insert( *pNode ) ) {
267 \p IsConst - constness boolean flag
269 The forward iterator for a split-list has the following features:
270 - it has no post-increment operator
271 - it depends on underlying ordered list iterator
272 - it is safe to iterate only inside RCU critical section
273 - deleting an item pointed by the iterator can cause to deadlock
275 Therefore, the use of iterators in concurrent environment is not good idea.
276 Use it for debug purpose only.
278 template <bool IsConst>
279 class iterator_type: protected base_class::template iterator_type<IsConst>
282 typedef typename base_class::template iterator_type<IsConst> iterator_base_class;
283 friend class SplitListSet;
286 /// Value pointer type (const for const iterator)
287 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
288 /// Value reference type (const for const iterator)
289 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
297 iterator_type( iterator_type const& src )
298 : iterator_base_class( src )
303 explicit iterator_type( iterator_base_class const& src )
304 : iterator_base_class( src )
309 /// Dereference operator
310 value_ptr operator ->() const
312 return &(iterator_base_class::operator->()->m_Value);
315 /// Dereference operator
316 value_ref operator *() const
318 return iterator_base_class::operator*().m_Value;
322 iterator_type& operator ++()
324 iterator_base_class::operator++();
328 /// Assignment operator
329 iterator_type& operator = (iterator_type const& src)
331 iterator_base_class::operator=(src);
335 /// Equality operator
337 bool operator ==(iterator_type<C> const& i ) const
339 return iterator_base_class::operator==(i);
342 /// Equality operator
344 bool operator !=(iterator_type<C> const& i ) const
346 return iterator_base_class::operator!=(i);
351 /// Initializes split-ordered list of default capacity
353 The default capacity is defined in bucket table constructor.
354 See intrusive::split_list::expandable_bucket_table, intrusive::split_list::static_bucket_table
355 which selects by intrusive::split_list::dynamic_bucket_table option.
361 /// Initializes split-ordered list
363 size_t nItemCount ///< estimate average of item count
364 , size_t nLoadFactor = 1 ///< load factor - average item count per bucket. Small integer up to 8, default is 1.
366 : base_class( nItemCount, nLoadFactor )
370 typedef iterator_type<false> iterator ; ///< Forward iterator
371 typedef iterator_type<true> const_iterator ; ///< Forward const iterator
373 /// Returns a forward iterator addressing the first element in a set
375 For empty set \code begin() == end() \endcode
379 return iterator( base_class::begin() );
382 /// Returns an iterator that addresses the location succeeding the last element in a set
384 Do not use the value returned by <tt>end</tt> function to access any item.
385 The returned value can be used only to control reaching the end of the set.
386 For empty set \code begin() == end() \endcode
390 return iterator( base_class::end() );
393 /// Returns a forward const iterator addressing the first element in a set
394 const_iterator begin() const
396 return const_iterator( base_class::begin() );
399 /// Returns an const iterator that addresses the location succeeding the last element in a set
400 const_iterator end() const
402 return const_iterator( base_class::end() );
408 The function creates a node with copy of \p val value
409 and then inserts the node created into the set.
411 The type \p Q should contain as minimum the complete key for the node.
412 The object of \p value_type should be constructible from a value of type \p Q.
413 In trivial case, \p Q is equal to \p value_type.
415 The function applies RCU lock internally.
417 Returns \p true if \p val is inserted into the set, \p false otherwise.
419 template <typename Q>
420 bool insert( Q const& val )
422 return insert_node( alloc_node( val ) );
427 The function allows to split creating of new item into two part:
428 - create item with key only
429 - insert new item into the set
430 - if inserting is success, calls \p f functor to initialize value-field of \p val.
432 The functor signature is:
434 void func( value_type& val );
436 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
437 \p val no any other changes could be made on this set's item by concurrent threads.
438 The user-defined functor is called only if the inserting is success. It may be passed by reference
439 using <tt>boost::ref</tt>
441 The function applies RCU lock internally.
443 template <typename Q, typename Func>
444 bool insert( Q const& val, Func f )
446 scoped_node_ptr pNode( alloc_node( val ));
448 if ( base_class::insert( *pNode, [&f](node_type& node) { cds::unref(f)( node.m_Value ) ; } )) {
455 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
457 Returns \p true if inserting successful, \p false otherwise.
459 The function applies RCU lock internally.
461 template <typename... Args>
462 bool emplace( Args&&... args )
464 return insert_node( alloc_node( std::forward<Args>(args)...));
467 /// Ensures that the \p item exists in the set
469 The operation performs inserting or changing data with lock-free manner.
471 If the \p val key not found in the set, then the new item created from \p val
472 is inserted into the set. Otherwise, the functor \p func is called with the item found.
473 The functor \p Func should be a function with signature:
475 void func( bool bNew, value_type& item, const Q& val );
480 void operator()( bool bNew, value_type& item, const Q& val );
485 - \p bNew - \p true if the item has been inserted, \p false otherwise
486 - \p item - item of the set
487 - \p val - argument \p val passed into the \p ensure function
489 The functor may change non-key fields of the \p item; however, \p func must guarantee
490 that during changing no any other modifications could be made on this item by concurrent threads.
492 You may pass \p func argument by reference using <tt>boost::ref</tt>.
494 The function applies RCU lock internally.
496 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
497 \p second is true if new item has been added or \p false if the item with \p key
498 already is in the set.
500 template <typename Q, typename Func>
501 std::pair<bool, bool> ensure( Q const& val, Func func )
503 scoped_node_ptr pNode( alloc_node( val ));
505 std::pair<bool, bool> bRet = base_class::ensure( *pNode,
506 [&func, &val]( bool bNew, node_type& item, node_type const& /*val*/ ) {
507 cds::unref(func)( bNew, item.m_Value, val );
509 if ( bRet.first && bRet.second )
514 /// Deletes \p key from the set
515 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_val
517 Since the key of SplitListSet's item type \p value_type is not explicitly specified,
518 template parameter \p Q defines the key type searching in the list.
519 The set item comparator should be able to compare the values of type \p value_type
522 RCU \p synchronize method can be called. RCU should not be locked.
524 Return \p true if key is found and deleted, \p false otherwise
526 template <typename Q>
527 bool erase( Q const& key )
529 return base_class::erase( key );
532 /// Deletes the item from the set using \p pred predicate for searching
534 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_val "erase(Q const&)"
535 but \p pred is used for key comparing.
536 \p Less functor has the interface like \p std::less.
537 \p Less must imply the same element order as the comparator used for building the set.
539 template <typename Q, typename Less>
540 bool erase_with( Q const& key, Less pred )
542 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type() );
545 /// Deletes \p key from the set
546 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_func
548 The function searches an item with key \p key, calls \p f functor
549 and deletes the item. If \p key is not found, the functor is not called.
551 The functor \p Func interface:
554 void operator()(value_type const& val);
557 The functor may be passed by reference using <tt>boost:ref</tt>
559 Since the key of SplitListSet's \p value_type is not explicitly specified,
560 template parameter \p Q defines the key type searching in the list.
561 The list item comparator should be able to compare the values of the type \p value_type
564 RCU \p synchronize method can be called. RCU should not be locked.
566 Return \p true if key is found and deleted, \p false otherwise
568 template <typename Q, typename Func>
569 bool erase( Q const& key, Func f )
571 return base_class::erase( key, [&f](node_type& node) { cds::unref(f)( node.m_Value ); } );
574 /// Deletes the item from the set using \p pred predicate for searching
576 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_func "erase(Q const&, Func)"
577 but \p pred is used for key comparing.
578 \p Less functor has the interface like \p std::less.
579 \p Less must imply the same element order as the comparator used for building the set.
581 template <typename Q, typename Less, typename Func>
582 bool erase_with( Q const& key, Less pred, Func f )
584 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type(),
585 [&f](node_type& node) { cds::unref(f)( node.m_Value ); } );
588 /// Extracts an item from the set
589 /** \anchor cds_nonintrusive_SplitListSet_rcu_extract
590 The function searches an item with key equal to \p val in the set,
591 unlinks it from the set, places item pointer into \p dest argument, and returns \p true.
592 If the item with the key equal to \p val is not found the function return \p false.
594 @note The function does NOT call RCU read-side lock or synchronization,
595 and does NOT dispose the item found. It just excludes the item from the set
596 and returns a pointer to item found.
597 You should lock RCU before calling of the function, and you should synchronize RCU
598 outside the RCU lock to free extracted item
601 typedef cds::urcu::gc< general_buffered<> > rcu;
602 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
604 splitlist_set theSet;
607 splitlist_set::exempt_ptr p;
609 // first, we should lock RCU
610 splitlist_set::rcu_lock lock;
612 // Now, you can apply extract function
613 // Note that you must not delete the item found inside the RCU lock
614 if ( theSet.extract( p, 10 )) {
615 // do something with p
620 // We may safely release p here
621 // release() passes the pointer to RCU reclamation cycle
625 template <typename Q>
626 bool extract( exempt_ptr& dest, Q const& val )
628 node_type * pNode = base_class::extract_( val, key_comparator() );
636 /// Extracts an item from the set using \p pred predicate for searching
638 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_extract "extract(exempt_ptr&, Q const&)"
639 but \p pred is used for key comparing.
640 \p Less functor has the interface like \p std::less.
641 \p pred must imply the same element order as the comparator used for building the set.
643 template <typename Q, typename Less>
644 bool extract_with( exempt_ptr& dest, Q const& val, Less pred )
646 node_type * pNode = base_class::extract_with_( val, typename maker::template predicate_wrapper<Less>::type());
654 /// Finds the key \p val
655 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_func
657 The function searches the item with key equal to \p val and calls the functor \p f for item found.
658 The interface of \p Func functor is:
661 void operator()( value_type& item, Q& val );
664 where \p item is the item found, \p val is the <tt>find</tt> function argument.
666 You may pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
668 The functor may change non-key fields of \p item. Note that the functor is only guarantee
669 that \p item cannot be disposed during functor is executing.
670 The functor does not serialize simultaneous access to the set's \p item. If such access is
671 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
673 The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor
674 may modify both arguments.
676 Note the hash functor specified for class \p Traits template parameter
677 should accept a parameter of type \p Q that can be not the same as \p value_type.
679 The function makes RCU lock internally.
681 The function returns \p true if \p val is found, \p false otherwise.
683 template <typename Q, typename Func>
684 bool find( Q& val, Func f )
686 return find_( val, f );
689 /// Finds the key \p val using \p pred predicate for searching
691 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_func "find(Q&, Func)"
692 but \p pred is used for key comparing.
693 \p Less functor has the interface like \p std::less.
694 \p Less must imply the same element order as the comparator used for building the set.
696 template <typename Q, typename Less, typename Func>
697 bool find_with( Q& val, Less pred, Func f )
699 return find_with_( val, pred, f );
702 /// Find the key \p val
703 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_cfunc
705 The function searches the item with key equal to \p val and calls the functor \p f for item found.
706 The interface of \p Func functor is:
709 void operator()( value_type& item, Q const& val );
712 where \p item is the item found, \p val is the <tt>find</tt> function argument.
714 You may pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
716 The functor may change non-key fields of \p item. Note that the functor is only guarantee
717 that \p item cannot be disposed during functor is executing.
718 The functor does not serialize simultaneous access to the set's \p item. If such access is
719 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
721 Note the hash functor specified for class \p Traits template parameter
722 should accept a parameter of type \p Q that can be not the same as \p value_type.
724 The function makes RCU lock internally.
726 The function returns \p true if \p val is found, \p false otherwise.
728 template <typename Q, typename Func>
729 bool find( Q const& val, Func f )
731 return find_( val, f );
734 /// Finds the key \p val using \p pred predicate for searching
736 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_cfunc "find(Q const&, Func)"
737 but \p pred is used for key comparing.
738 \p Less functor has the interface like \p std::less.
739 \p Less must imply the same element order as the comparator used for building the set.
741 template <typename Q, typename Less, typename Func>
742 bool find_with( Q const& val, Less pred, Func f )
744 return find_with_( val, pred, f );
747 /// Finds the key \p val
748 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_val
750 The function searches the item with key equal to \p val
751 and returns \p true if it is found, and \p false otherwise.
753 Note the hash functor specified for class \p Traits template parameter
754 should accept a parameter of type \p Q that can be not the same as \p value_type.
756 The function makes RCU lock internally.
758 template <typename Q>
759 bool find( Q const& val )
761 return base_class::find( val );
764 /// Finds the key \p val using \p pred predicate for searching
766 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_val "find(Q const&)"
767 but \p pred is used for key comparing.
768 \p Less functor has the interface like \p std::less.
769 \p Less must imply the same element order as the comparator used for building the set.
771 template <typename Q, typename Less>
772 bool find_with( Q const& val, Less pred )
774 return base_class::find_with( val, typename maker::template predicate_wrapper<Less>::type() );
777 /// Finds the key \p val and return the item found
778 /** \anchor cds_nonintrusive_SplitListSet_rcu_get
779 The function searches the item with key equal to \p val and returns the pointer to item found.
780 If \p val is not found it returns \p nullptr.
782 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
784 RCU should be locked before call of this function.
785 Returned item is valid only while RCU is locked:
787 typedef cds::urcu::gc< general_buffered<> > rcu;
788 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
789 splitlist_set theSet;
793 splitlist_set::rcu_lock lock;
795 foo * pVal = theSet.get( 5 );
800 // Unlock RCU by rcu_lock destructor
801 // pVal can be retired by disposer at any time after RCU has been unlocked
805 template <typename Q>
806 value_type * get( Q const& val )
808 node_type * pNode = base_class::get( val );
809 return pNode ? &pNode->m_Value : nullptr;
812 /// Finds the key \p val and return the item found
814 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_get "get(Q const&)"
815 but \p pred is used for comparing the keys.
817 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
819 \p pred must imply the same element order as the comparator used for building the set.
821 template <typename Q, typename Less>
822 value_type * get_with( Q const& val, Less pred )
824 node_type * pNode = base_class::get_with( val, typename maker::template predicate_wrapper<Less>::type());
825 return pNode ? &pNode->m_Value : nullptr;
828 /// Clears the set (non-atomic)
830 The function unlink all items from the set.
831 The function is not atomic and not lock-free and should be used for debugging only.
833 RCU \p synchronize method can be called. RCU should not be locked.
840 /// Checks if the set is empty
842 Emptiness is checked by item counting: if item count is zero then assume that the set is empty.
843 Thus, the correct item counting feature is an important part of split-list set implementation.
847 return base_class::empty();
850 /// Returns item count in the set
853 return base_class::size();
858 }} // namespace cds::container
860 #endif // #ifndef __CDS_CONTAINER_SPLIT_LIST_SET_RCU_H