3 #ifndef __CDS_CONTAINER_SKIP_LIST_SET_RCU_H
4 #define __CDS_CONTAINER_SKIP_LIST_SET_RCU_H
6 #include <cds/intrusive/skip_list_rcu.h>
7 #include <cds/container/details/make_skip_list_set.h>
9 namespace cds { namespace container {
11 /// Lock-free skip-list set (template specialization for \ref cds_urcu_desc "RCU")
12 /** @ingroup cds_nonintrusive_set
13 \anchor cds_nonintrusive_SkipListSet_rcu
15 The implementation of well-known probabilistic data structure called skip-list
16 invented by W.Pugh in his papers:
17 - [1989] W.Pugh Skip Lists: A Probabilistic Alternative to Balanced Trees
18 - [1990] W.Pugh A Skip List Cookbook
20 A skip-list is a probabilistic data structure that provides expected logarithmic
21 time search without the need of rebalance. The skip-list is a collection of sorted
22 linked list. Nodes are ordered by key. Each node is linked into a subset of the lists.
23 Each list has a level, ranging from 0 to 32. The bottom-level list contains
24 all the nodes, and each higher-level list is a sublist of the lower-level lists.
25 Each node is created with a random top level (with a random height), and belongs
26 to all lists up to that level. The probability that a node has the height 1 is 1/2.
27 The probability that a node has the height N is 1/2 ** N (more precisely,
28 the distribution depends on an random generator provided, but our generators
31 The lock-free variant of skip-list is implemented according to book
32 - [2008] M.Herlihy, N.Shavit "The Art of Multiprocessor Programming",
33 chapter 14.4 "A Lock-Free Concurrent Skiplist"
36 - \p RCU - one of \ref cds_urcu_gc "RCU type".
37 - \p T - type to be stored in the list.
38 - \p Traits - type traits. See skip_list::type_traits for explanation.
40 It is possible to declare option-based list with cds::container::skip_list::make_traits metafunction istead of \p Traits template
42 Template argument list \p Options of cds::container::skip_list::make_traits metafunction are:
43 - opt::compare - key comparison functor. No default functor is provided.
44 If the option is not specified, the opt::less is used.
45 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
46 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
47 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
48 or opt::v::sequential_consistent (sequentially consisnent memory model).
49 - skip_list::random_level_generator - random level generator. Can be skip_list::xorshift, skip_list::turbo_pascal or
50 user-provided one. See skip_list::random_level_generator option description for explanation.
51 Default is \p %skip_list::turbo_pascal.
52 - opt::allocator - allocator for skip-list node. Default is \ref CDS_DEFAULT_ALLOCATOR.
53 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::Default is used.
54 - opt::stat - internal statistics. Available types: skip_list::stat, skip_list::empty_stat (the default)
55 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
57 @note Before including <tt><cds/container/skip_list_set_rcu.h></tt> you should include appropriate RCU header file,
58 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
62 The class supports a forward iterator (\ref iterator and \ref const_iterator).
63 The iteration is ordered.
65 You may iterate over skip-list set items only under RCU lock.
66 Only in this case the iterator is thread-safe since
67 while RCU is locked any set's item cannot be reclaimed.
69 The requirement of RCU lock during iterating means that deletion of the elements (i.e. \ref erase)
72 @warning The iterator object cannot be passed between threads
74 Example how to use skip-list set iterators:
76 // First, you should include the header for RCU type you have chosen
77 #include <cds/urcu/general_buffered.h>
78 #include <cds/container/skip_list_set_rcu.h>
80 typedef cds::urcu::gc< cds::urcu::general_buffered<> > rcu_type;
86 // Traits for your skip-list.
87 // At least, you should define cds::opt::less or cds::opt::compare for Foo struct
88 struct my_traits: public cds::continer::skip_list::type_traits
92 typedef cds::container::SkipListSet< rcu_type, Foo, my_traits > my_skiplist_set;
94 my_skiplist_set theSet;
100 // Apply RCU locking manually
101 typename rcu_type::scoped_lock sl;
103 for ( auto it = theList.begin(); it != theList.end(); ++it ) {
107 // rcu_type::scoped_lock destructor releases RCU lock implicitly
111 \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate
112 all elements in the set: any concurrent deletion can exclude the element
113 pointed by the iterator from the set, and your iteration can be terminated
114 before end of the set. Therefore, such iteration is more suitable for debugging purposes
116 The iterator class supports the following minimalistic interface:
123 iterator( iterator const& s);
125 value_type * operator ->() const;
126 value_type& operator *() const;
129 iterator& operator ++();
132 iterator& operator = (const iterator& src);
134 bool operator ==(iterator const& i ) const;
135 bool operator !=(iterator const& i ) const;
138 Note, the iterator object returned by \ref end, \p cend member functions points to \p nullptr and should not be dereferenced.
143 #ifdef CDS_DOXYGEN_INVOKED
144 typename Traits = skip_list::type_traits
149 class SkipListSet< cds::urcu::gc< RCU >, T, Traits >:
150 #ifdef CDS_DOXYGEN_INVOKED
151 protected intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
153 protected details::make_skip_list_set< cds::urcu::gc< RCU >, T, Traits >::type
157 typedef details::make_skip_list_set< cds::urcu::gc< RCU >, T, Traits > maker;
158 typedef typename maker::type base_class;
161 typedef typename base_class::gc gc ; ///< Garbage collector used
162 typedef T value_type ; ///< Value type stored in the set
163 typedef Traits options ; ///< Options specified
165 typedef typename base_class::back_off back_off ; ///< Back-off strategy used
166 typedef typename options::allocator allocator_type ; ///< Allocator type used for allocate/deallocate the skip-list nodes
167 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
168 typedef typename maker::key_comparator key_comparator ; ///< key compare functor
169 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
170 typedef typename options::random_level_generator random_level_generator ; ///< random level generator
171 typedef typename options::stat stat ; ///< internal statistics type
172 typedef typename options::rcu_check_deadlock rcu_check_deadlock ; ///< Deadlock checking policy
176 typedef typename maker::node_type node_type;
177 typedef typename maker::node_allocator node_allocator;
179 typedef std::unique_ptr< node_type, typename maker::node_deallocator > scoped_node_ptr;
183 typedef typename base_class::rcu_lock rcu_lock; ///< RCU scoped lock
184 /// Group of \p extract_xxx functions do not require external locking
185 static CDS_CONSTEXPR_CONST bool c_bExtractLockExternal = base_class::c_bExtractLockExternal;
187 /// pointer to extracted node
188 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_type_traits::disposer > exempt_ptr;
192 unsigned int random_level()
194 return base_class::random_level();
197 value_type * to_value_ptr( node_type * pNode ) const CDS_NOEXCEPT
199 return pNode ? &pNode->m_Value : nullptr;
205 # ifndef CDS_CXX11_LAMBDA_SUPPORT
206 template <typename Func>
207 struct insert_functor
211 insert_functor ( Func f )
215 void operator()( node_type& node )
217 cds::unref(m_func)( node.m_Value );
221 template <typename Q, typename Func>
222 struct ensure_functor
227 ensure_functor( Q const& arg, Func f )
232 void operator ()( bool bNew, node_type& node, node_type& )
234 cds::unref(m_func)( bNew, node.m_Value, m_arg );
238 template <typename Func>
243 find_functor( Func f )
247 template <typename Q>
248 void operator ()( node_type& node, Q& val )
250 cds::unref(m_func)( node.m_Value, val );
254 template <typename Func>
259 erase_functor( Func f )
263 void operator()( node_type const& node )
265 cds::unref(m_func)( node.m_Value );
269 template <typename Func>
270 struct extract_copy_wrapper
273 extract_copy_wrapper( Func f )
277 template <typename Q>
278 void operator()( Q& dest, node_type& src )
280 cds::unref(m_func)(dest, src.m_Value);
284 struct extract_assign_wrapper
286 template <typename Q>
287 void operator()( Q& dest, node_type& src ) const
292 # endif // ifndef CDS_CXX11_LAMBDA_SUPPORT
302 /// Destructor destroys the set object
308 typedef skip_list::details::iterator< typename base_class::iterator > iterator;
310 /// Const iterator type
311 typedef skip_list::details::iterator< typename base_class::const_iterator > const_iterator;
313 /// Returns a forward iterator addressing the first element in a set
316 return iterator( base_class::begin() );
319 /// Returns a forward const iterator addressing the first element in a set
321 const_iterator begin() const
323 return const_iterator( base_class::begin() );
325 const_iterator cbegin()
327 return const_iterator( base_class::cbegin() );
331 /// Returns a forward iterator that addresses the location succeeding the last element in a set.
334 return iterator( base_class::end() );
337 /// Returns a forward const iterator that addresses the location succeeding the last element in a set.
339 const_iterator end() const
341 return const_iterator( base_class::end() );
343 const_iterator cend()
345 return const_iterator( base_class::cend() );
352 The function creates a node with copy of \p val value
353 and then inserts the node created into the set.
355 The type \p Q should contain as minimum the complete key for the node.
356 The object of \ref value_type should be constructible from a value of type \p Q.
357 In trivial case, \p Q is equal to \ref value_type.
359 RCU \p synchronize method can be called. RCU should not be locked.
361 Returns \p true if \p val is inserted into the set, \p false otherwise.
363 template <typename Q>
364 bool insert( Q const& val )
366 scoped_node_ptr sp( node_allocator().New( random_level(), val ));
367 if ( base_class::insert( *sp.get() )) {
376 The function allows to split creating of new item into two part:
377 - create item with key only
378 - insert new item into the set
379 - if inserting is success, calls \p f functor to initialize value-fields of \p val.
381 The functor signature is:
383 void func( value_type& val );
385 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
386 \p val no any other changes could be made on this set's item by concurrent threads.
387 The user-defined functor is called only if the inserting is success. It may be passed by reference
388 using <tt>boost::ref</tt>
390 RCU \p synchronize method can be called. RCU should not be locked.
392 template <typename Q, typename Func>
393 bool insert( Q const& val, Func f )
395 scoped_node_ptr sp( node_allocator().New( random_level(), val ));
396 # ifdef CDS_CXX11_LAMBDA_SUPPORT
397 if ( base_class::insert( *sp.get(), [&f]( node_type& val ) { cds::unref(f)( val.m_Value ); } ))
399 insert_functor<Func> wrapper(f);
400 if ( base_class::insert( *sp, cds::ref(wrapper) ))
409 /// Ensures that the item exists in the set
411 The operation performs inserting or changing data with lock-free manner.
413 If the \p val key not found in the set, then the new item created from \p val
414 is inserted into the set. Otherwise, the functor \p func is called with the item found.
415 The functor \p Func should be a function with signature:
417 void func( bool bNew, value_type& item, const Q& val );
422 void operator()( bool bNew, value_type& item, const Q& val );
427 - \p bNew - \p true if the item has been inserted, \p false otherwise
428 - \p item - item of the set
429 - \p val - argument \p key passed into the \p ensure function
431 The functor may change non-key fields of the \p item; however, \p func must guarantee
432 that during changing no any other modifications could be made on this item by concurrent threads.
434 You may pass \p func argument by reference using <tt>boost::ref</tt>.
436 RCU \p synchronize method can be called. RCU should not be locked.
438 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
439 \p second is true if new item has been added or \p false if the item with \p key
440 already is in the set.
442 template <typename Q, typename Func>
443 std::pair<bool, bool> ensure( const Q& val, Func func )
445 scoped_node_ptr sp( node_allocator().New( random_level(), val ));
446 # ifdef CDS_CXX11_LAMBDA_SUPPORT
447 std::pair<bool, bool> bRes = base_class::ensure( *sp,
448 [&func, &val](bool bNew, node_type& node, node_type&){ cds::unref(func)( bNew, node.m_Value, val ); });
450 ensure_functor<Q, Func> wrapper( val, func );
451 std::pair<bool, bool> bRes = base_class::ensure( *sp, cds::ref(wrapper));
453 if ( bRes.first && bRes.second )
458 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
460 Returns \p true if inserting successful, \p false otherwise.
462 RCU \p synchronize method can be called. RCU should not be locked.
464 template <typename... Args>
465 bool emplace( Args&&... args )
467 scoped_node_ptr sp( node_allocator().New( random_level(), std::forward<Args>(args)... ));
468 if ( base_class::insert( *sp.get() )) {
475 /// Delete \p key from the set
476 /** \anchor cds_nonintrusive_SkipListSet_rcu_erase_val
478 The item comparator should be able to compare the type \p value_type
481 RCU \p synchronize method can be called. RCU should not be locked.
483 Return \p true if key is found and deleted, \p false otherwise
485 template <typename Q>
486 bool erase( Q const& key )
488 return base_class::erase( key );
491 /// Deletes the item from the set using \p pred predicate for searching
493 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_erase_val "erase(Q const&)"
494 but \p pred is used for key comparing.
495 \p Less functor has the interface like \p std::less.
496 \p Less must imply the same element order as the comparator used for building the set.
498 template <typename Q, typename Less>
499 bool erase_with( Q const& key, Less pred )
501 return base_class::erase_with( key, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >());
504 /// Delete \p key from the set
505 /** \anchor cds_nonintrusive_SkipListSet_rcu_erase_func
507 The function searches an item with key \p key, calls \p f functor
508 and deletes the item. If \p key is not found, the functor is not called.
510 The functor \p Func interface:
513 void operator()(value_type const& val);
516 The functor may be passed by reference using <tt>boost:ref</tt>
518 Since the key of MichaelHashSet's \p value_type is not explicitly specified,
519 template parameter \p Q defines the key type searching in the list.
520 The list item comparator should be able to compare the type \p T of list item
523 RCU \p synchronize method can be called. RCU should not be locked.
525 Return \p true if key is found and deleted, \p false otherwise
529 template <typename Q, typename Func>
530 bool erase( Q const& key, Func f )
532 # ifdef CDS_CXX11_LAMBDA_SUPPORT
533 return base_class::erase( key, [&f]( node_type const& node) { cds::unref(f)( node.m_Value ); } );
535 erase_functor<Func> wrapper(f);
536 return base_class::erase( key, cds::ref(wrapper));
540 /// Deletes the item from the set using \p pred predicate for searching
542 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_erase_func "erase(Q const&, Func)"
543 but \p pred is used for key comparing.
544 \p Less functor has the interface like \p std::less.
545 \p Less must imply the same element order as the comparator used for building the set.
547 template <typename Q, typename Less, typename Func>
548 bool erase_with( Q const& key, Less pred, Func f )
550 # ifdef CDS_CXX11_LAMBDA_SUPPORT
551 return base_class::erase_with( key, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(),
552 [&f]( node_type const& node) { cds::unref(f)( node.m_Value ); } );
554 erase_functor<Func> wrapper(f);
555 return base_class::erase_with( key, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(), cds::ref(wrapper));
559 /// Extracts the item from the set with specified \p key
560 /** \anchor cds_nonintrusive_SkipListSet_rcu_extract
561 The function searches an item with key equal to \p key in the set,
562 unlinks it from the set, and returns it in \p result parameter.
563 If the item with key equal to \p key is not found the function returns \p false.
565 Note the compare functor from \p Traits class' template argument
566 should accept a parameter of type \p Q that can be not the same as \p value_type.
568 RCU \p synchronize method can be called. RCU should NOT be locked.
569 The function does not free the item found.
570 The item will be implicitly freed when \p result object is destroyed or when
571 <tt>result.release()</tt> is called, see \p cds::urcu::exempt_ptr for explanation.
572 @note Before reusing \p result object you should call its \p release() method.
574 template <typename Q>
575 bool extract( exempt_ptr& result, Q const& key )
577 return base_class::do_extract( result, key );
580 /// Extracts the item from the set with comparing functor \p pred
582 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_extract "extract(exempt_ptr&, Q const&)"
583 but \p pred predicate is used for key comparing.
584 \p Less has the semantics like \p std::less.
585 \p pred must imply the same element order as the comparator used for building the set.
587 template <typename Q, typename Less>
588 bool extract_with( exempt_ptr& result, Q const& key, Less pred )
590 return base_class::do_extract_with( result, key, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >());
593 /// Extracts an item with minimal key from the set
595 The function searches an item with minimal key, unlinks it, and returns the item found in \p result parameter.
596 If the skip-list is empty the function returns \p false.
598 RCU \p synchronize method can be called. RCU should NOT be locked.
599 The function does not free the item found.
600 The item will be implicitly freed when \p result object is destroyed or when
601 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
602 @note Before reusing \p result object you should call its \p release() method.
604 bool extract_min( exempt_ptr& result )
606 return base_class::do_extract_min(result);
609 /// Extracts an item with maximal key from the set
611 The function searches an item with maximal key, unlinks it from the set, and returns the item found
612 in \p result parameter. If the skip-list is empty the function returns \p false.
614 RCU \p synchronize method can be called. RCU should NOT be locked.
615 The function does not free the item found.
616 The item will be implicitly freed when \p result object is destroyed or when
617 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
618 @note Before reusing \p result object you should call its \p release() method.
620 bool extract_max(exempt_ptr& result)
622 return base_class::do_extract_max(result);
625 /// Find the key \p val
627 @anchor cds_nonintrusive_SkipListSet_rcu_find_func
629 The function searches the item with key equal to \p val and calls the functor \p f for item found.
630 The interface of \p Func functor is:
633 void operator()( value_type& item, Q& val );
636 where \p item is the item found, \p val is the <tt>find</tt> function argument.
638 You may pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
640 The functor may change non-key fields of \p item. Note that the functor is only guarantee
641 that \p item cannot be disposed during functor is executing.
642 The functor does not serialize simultaneous access to the set's \p item. If such access is
643 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
645 The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor
646 can modify both arguments.
648 Note the hash functor specified for class \p Traits template parameter
649 should accept a parameter of type \p Q that may be not the same as \p value_type.
651 The function applies RCU lock internally.
653 The function returns \p true if \p val is found, \p false otherwise.
655 template <typename Q, typename Func>
656 bool find( Q& val, Func f )
658 # ifdef CDS_CXX11_LAMBDA_SUPPORT
659 return base_class::find( val, [&f]( node_type& node, Q& v ) { cds::unref(f)( node.m_Value, v ); });
661 find_functor<Func> wrapper(f);
662 return base_class::find( val, cds::ref(wrapper));
666 /// Finds the key \p val using \p pred predicate for searching
668 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_find_func "find(Q&, Func)"
669 but \p pred is used for key comparing.
670 \p Less functor has the interface like \p std::less.
671 \p Less must imply the same element order as the comparator used for building the set.
673 template <typename Q, typename Less, typename Func>
674 bool find_with( Q& val, Less pred, Func f )
676 # ifdef CDS_CXX11_LAMBDA_SUPPORT
677 return base_class::find_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(),
678 [&f]( node_type& node, Q& v ) { cds::unref(f)( node.m_Value, v ); } );
680 find_functor<Func> wrapper(f);
681 return base_class::find_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(),
686 /// Find the key \p val
687 /** @anchor cds_nonintrusive_SkipListSet_rcu_find_cfunc
689 The function searches the item with key equal to \p val and calls the functor \p f for item found.
690 The interface of \p Func functor is:
693 void operator()( value_type& item, Q const& val );
696 where \p item is the item found, \p val is the <tt>find</tt> function argument.
698 You may pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
700 The functor may change non-key fields of \p item. Note that the functor is only guarantee
701 that \p item cannot be disposed during functor is executing.
702 The functor does not serialize simultaneous access to the set's \p item. If such access is
703 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
705 Note the hash functor specified for class \p Traits template parameter
706 should accept a parameter of type \p Q that may be not the same as \p value_type.
708 The function applies RCU lock internally.
710 The function returns \p true if \p val is found, \p false otherwise.
712 template <typename Q, typename Func>
713 bool find( Q const& val, Func f )
715 # ifdef CDS_CXX11_LAMBDA_SUPPORT
716 return base_class::find( val, [&f]( node_type& node, Q const& v ) { cds::unref(f)( node.m_Value, v ); });
718 find_functor<Func> wrapper(f);
719 return base_class::find( val, cds::ref(wrapper));
723 /// Finds the key \p val using \p pred predicate for searching
725 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_find_cfunc "find(Q const&, Func)"
726 but \p pred is used for key comparing.
727 \p Less functor has the semantics like \p std::less.
728 \p Less must imply the same element order as the comparator used for building the set.
730 template <typename Q, typename Less, typename Func>
731 bool find_with( Q const& val, Less pred, Func f )
733 # ifdef CDS_CXX11_LAMBDA_SUPPORT
734 return base_class::find_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(),
735 [&f]( node_type& node, Q const& v ) { cds::unref(f)( node.m_Value, v ); } );
737 find_functor<Func> wrapper(f);
738 return base_class::find_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >(),
743 /// Find the key \p val
744 /** @anchor cds_nonintrusive_SkipListSet_rcu_find_val
746 The function searches the item with key equal to \p val
747 and returns \p true if it is found, and \p false otherwise.
749 Note the hash functor specified for class \p Traits template parameter
750 should accept a parameter of type \p Q that may be not the same as \ref value_type.
752 The function applies RCU lock internally.
754 template <typename Q>
755 bool find( Q const & val )
757 return base_class::find( val );
760 /// Finds the key \p val using \p pred predicate for searching
762 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_find_val "find(Q const&)"
763 but \p pred is used for key comparing.
764 \p Less functor has the interface like \p std::less.
765 \p Less must imply the same element order as the comparator used for building the set.
767 template <typename Q, typename Less>
768 bool find_with( Q const& val, Less pred )
770 return base_class::find_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >());
773 /// Finds \p key and return the item found
774 /** \anchor cds_nonintrusive_SkipListSet_rcu_get
775 The function searches the item with key equal to \p key and returns the pointer to item found.
776 If \p key is not found it returns \p nullptr.
778 Note the compare functor in \p Traits class' template argument
779 should accept a parameter of type \p Q that can be not the same as \p value_type.
781 RCU should be locked before call of this function.
782 Returned item is valid only while RCU is locked:
784 typedef cds::container::SkipListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > skip_list;
789 skip_list::rcu_lock lock;
791 foo * pVal = theList.get( 5 );
795 // Unlock RCU by rcu_lock destructor
796 // pVal can be freed at any time after RCU unlocking
800 After RCU unlocking the \p %force_dispose member function can be called manually,
801 see \ref force_dispose for explanation.
803 template <typename Q>
804 value_type * get( Q const& key )
806 return to_value_ptr( base_class::get( key ));
809 /// Finds the key \p val and return the item found
811 The function is an analog of \ref cds_nonintrusive_SkipListSet_rcu_get "get(Q const&)"
812 but \p pred is used for comparing the keys.
814 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
816 \p pred must imply the same element order as the comparator used for building the set.
818 template <typename Q, typename Less>
819 value_type * get_with( Q const& val, Less pred )
821 return to_value_ptr( base_class::get_with( val, cds::details::predicate_wrapper< node_type, Less, typename maker::value_accessor >() ));
824 /// Clears the set (non-atomic).
826 The function deletes all items from the set.
827 The function is not atomic, thus, in multi-threaded environment with parallel insertions
831 assert( set.empty() );
833 the assertion could be raised.
835 For each item the \ref disposer provided by \p Traits template parameter will be called.
842 /// Checks if the set is empty
845 return base_class::empty();
848 /// Returns item count in the set
850 The value returned depends on item counter type provided by \p Traits template parameter.
851 If it is atomicity::empty_item_counter this function always returns 0.
852 Therefore, the function is not suitable for checking the set emptiness, use \ref empty
853 member function for this purpose.
857 return base_class::size();
860 /// Returns const reference to internal statistics
861 stat const& statistics() const
863 return base_class::statistics();
866 /// Clears internal list of ready-to-delete items passing them to RCU reclamation cycle
868 See \ref cds_intrusive_SkipListSet_rcu_force_dispose "intrusive SkipListSet" for explanation
872 return base_class::force_dispose();
876 }} // namespace cds::container
878 #endif // #ifndef __CDS_CONTAINER_SKIP_LIST_SET_RCU_H