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>
9 namespace cds { namespace container {
11 /// Split-ordered list set (template specialization for \ref cds_urcu_desc "RCU")
12 /** @ingroup cds_nonintrusive_set
13 \anchor cds_nonintrusive_SplitListSet_rcu
15 Hash table implementation based on split-ordered list algorithm discovered by Ori Shalev and Nir Shavit, see
16 - [2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"
17 - [2008] Nir Shavit "The Art of Multiprocessor Programming"
19 See \p intrusive::SplitListSet for a brief description of the split-list algorithm.
22 - \p RCU - one of \ref cds_urcu_gc "RCU type"
23 - \p T - type of the value to be stored in the split-list.
24 - \p Traits - type traits, default is \p split_list::traits. Instead of declaring \p split_list::traits -based
25 struct you can apply option-based notation with \p split_list::make_traits metafunction.
29 The class supports a forward iterator (\ref iterator and \ref const_iterator).
30 The iteration is unordered.
32 You may iterate over split-list set items only under RCU lock.
33 Only in this case the iterator is thread-safe since
34 while RCU is locked any set's item cannot be reclaimed.
36 @warning The iterator object cannot be passed between threads
38 \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate
39 all elements in the set: any concurrent deletion can exclude the element
40 pointed by the iterator from the set, and your iteration can be terminated
41 before end of the set. Therefore, such iteration is more suitable for debugging purposes
43 The iterator class supports the following minimalistic interface:
50 iterator( iterator const& s);
52 value_type * operator ->() const;
53 value_type& operator *() const;
56 iterator& operator ++();
59 iterator& operator = (const iterator& src);
61 bool operator ==(iterator const& i ) const;
62 bool operator !=(iterator const& i ) const;
65 Note, the iterator object returned by \p end(), \p cend() member functions points to \p nullptr and should not be dereferenced.
69 You should decide what garbage collector you want, and what ordered list you want to use. Split-ordered list
70 is an original data structure based on an ordered list. Suppose, you want construct split-list set based on \p cds::urcu::general_buffered<> GC
71 and \p LazyList as ordered list implementation. So, you beginning your program with following include:
73 #include <cds/urcu/general_buffered.h>
74 #include <cds/container/lazy_list_rcu.h>
75 #include <cds/container/split_list_set_rcu.h>
77 namespace cc = cds::container;
79 // The data belonged to split-ordered list
81 int nKey; // key field
82 std::string strValue ; // value field
85 The inclusion order is important:
86 - first, include one of \ref cds_urcu_gc "RCU implementation" (<tt>cds/urcu/general_buffered.h</tt> in our case)
87 - second, include file for ordered-list implementation (for this example, <tt>cds/container/lazy_list_rcu.h</tt>),
88 - then, the header for RCU-based split-list set <tt>cds/container/split_list_set_rcu.h</tt>.
90 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.
91 Note that we define several function in \p foo_hash and \p foo_less functors for different argument types since we want call our \p %SplitListSet
92 object by the key of type \p int and by the value of type \p foo.
94 The second attention: instead of using \p %LazyList in \p %SplitListSet traits we use \p cds::contaner::lazy_list_tag tag for the lazy list.
95 The split-list requires significant support from underlying ordered list class and it is not good idea to dive you
96 into deep implementation details of split-list and ordered list interrelations. The tag paradigm simplifies split-list interface.
101 size_t operator()( int key ) const { return std::hash( key ) ; }
102 size_t operator()( foo const& item ) const { return std::hash( item.nKey ) ; }
107 bool operator()(int i, foo const& f ) const { return i < f.nKey ; }
108 bool operator()(foo const& f, int i ) const { return f.nKey < i ; }
109 bool operator()(foo const& f1, foo const& f2) const { return f1.nKey < f2.nKey; }
112 // SplitListSet traits
113 struct foo_set_traits: public cc::split_list::traits
115 typedef cc::lazy_list_tag ordered_list ; // what type of ordered list we want to use
116 typedef foo_hash hash ; // hash functor for our data stored in split-list set
118 // Type traits for our LazyList class
119 struct ordered_list_traits: public cc::lazy_list::traits
121 typedef foo_less less ; // use our foo_less as comparator to order list nodes
126 Now you are ready to declare our set class based on \p %SplitListSet:
128 typedef cc::SplitListSet< cds::urcu::gc<cds::urcu::general_buffered<> >, foo, foo_set_traits > foo_set;
131 You may use the modern option-based declaration instead of classic type-traits-based one:
133 typedef cc:SplitListSet<
134 cds::urcu::gc<cds::urcu::general_buffered<> > // RCU type used
135 ,foo // type of data stored
136 ,cc::split_list::make_traits< // metafunction to build split-list traits
137 cc::split_list::ordered_list<cc::lazy_list_tag> // tag for underlying ordered list implementation
138 ,cc::opt::hash< foo_hash > // hash functor
139 ,cc::split_list::ordered_list_traits< // ordered list traits
140 cc::lazy_list::make_traits< // metafunction to build lazy list traits
141 cc::opt::less< foo_less > // less-based compare functor
147 In case of option-based declaration using \p split_list::make_traits metafunction
148 the struct \p foo_set_traits is not required.
150 Now, the set of type \p foo_set is ready to use in your program.
152 Note that in this example we show only mandatory \p traits parts, optional ones is the default and they are inherited
153 from \p container::split_list::traits.
154 There are many other options for deep tuning of the split-list and ordered-list containers.
159 #ifdef CDS_DOXYGEN_INVOKED
160 class Traits = split_list::traits
165 class SplitListSet< cds::urcu::gc< RCU >, T, Traits >:
166 #ifdef CDS_DOXYGEN_INVOKED
167 protected intrusive::SplitListSet< cds::urcu::gc< RCU >, typename Traits::ordered_list, Traits >
169 protected details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> >::type
174 typedef details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> > maker;
175 typedef typename maker::type base_class;
179 typedef cds::urcu::gc< RCU > gc; ///< RCU-based garbage collector
180 typedef T value_type; ///< Type of value to be storedin the set
181 typedef Traits traits; ///< \p Traits template argument
183 typedef typename maker::ordered_list ordered_list; ///< Underlying ordered list class
184 typedef typename base_class::key_comparator key_comparator; ///< key compare functor
186 /// Hash functor for \ref value_type and all its derivatives that you use
187 typedef typename base_class::hash hash;
188 typedef typename base_class::item_counter item_counter; ///< Item counter type
190 typedef typename base_class::rcu_lock rcu_lock ; ///< RCU scoped lock
191 /// Group of \p extract_xxx functions require external locking if underlying ordered list requires that
192 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal;
196 typedef typename maker::cxx_node_allocator cxx_node_allocator;
197 typedef typename maker::node_type node_type;
201 /// pointer to extracted node
202 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::ordered_list_traits::disposer > exempt_ptr;
206 template <typename Q, typename Func>
207 bool find_( Q& val, Func f )
209 return base_class::find( val, [&f]( node_type& item, Q& val ) { f(item.m_Value, val) ; } );
212 template <typename Q, typename Less, typename Func>
213 bool find_with_( Q& val, Less pred, Func f )
215 return base_class::find_with( val, typename maker::template predicate_wrapper<Less>::type(),
216 [&f]( node_type& item, Q& val ) { f(item.m_Value, val) ; } );
219 template <typename Q>
220 static node_type * alloc_node( Q const& v )
222 return cxx_node_allocator().New( v );
225 template <typename... Args>
226 static node_type * alloc_node( Args&&... args )
228 return cxx_node_allocator().MoveNew( std::forward<Args>(args)...);
231 static void free_node( node_type * pNode )
233 cxx_node_allocator().Delete( pNode );
236 struct node_disposer {
237 void operator()( node_type * pNode )
242 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
244 bool insert_node( node_type * pNode )
246 assert( pNode != nullptr );
247 scoped_node_ptr p(pNode);
249 if ( base_class::insert( *pNode ) ) {
261 \p IsConst - constness boolean flag
263 The forward iterator for a split-list has the following features:
264 - it has no post-increment operator
265 - it depends on underlying ordered list iterator
266 - it is safe to iterate only inside RCU critical section
267 - deleting an item pointed by the iterator can cause to deadlock
269 Therefore, the use of iterators in concurrent environment is not good idea.
270 Use it for debug purpose only.
272 template <bool IsConst>
273 class iterator_type: protected base_class::template iterator_type<IsConst>
276 typedef typename base_class::template iterator_type<IsConst> iterator_base_class;
277 friend class SplitListSet;
280 /// Value pointer type (const for const iterator)
281 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
282 /// Value reference type (const for const iterator)
283 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
291 iterator_type( iterator_type const& src )
292 : iterator_base_class( src )
297 explicit iterator_type( iterator_base_class const& src )
298 : iterator_base_class( src )
303 /// Dereference operator
304 value_ptr operator ->() const
306 return &(iterator_base_class::operator->()->m_Value);
309 /// Dereference operator
310 value_ref operator *() const
312 return iterator_base_class::operator*().m_Value;
316 iterator_type& operator ++()
318 iterator_base_class::operator++();
322 /// Assignment operator
323 iterator_type& operator = (iterator_type const& src)
325 iterator_base_class::operator=(src);
329 /// Equality operator
331 bool operator ==(iterator_type<C> const& i ) const
333 return iterator_base_class::operator==(i);
336 /// Equality operator
338 bool operator !=(iterator_type<C> const& i ) const
340 return iterator_base_class::operator!=(i);
345 /// Initializes split-ordered list of default capacity
347 The default capacity is defined in bucket table constructor.
348 See \p intrusive::split_list::expandable_bucket_table, \p intrusive::split_list::static_bucket_table
349 which selects by \p container::split_list::dynamic_bucket_table option.
355 /// Initializes split-ordered list
357 size_t nItemCount ///< estimated average of item count
358 , size_t nLoadFactor = 1 ///< load factor - average item count per bucket. Small integer up to 8, default is 1.
360 : base_class( nItemCount, nLoadFactor )
364 typedef iterator_type<false> iterator ; ///< Forward iterator
365 typedef iterator_type<true> const_iterator ; ///< Forward const iterator
367 /// Returns a forward iterator addressing the first element in a set
369 For empty set \code begin() == end() \endcode
373 return iterator( base_class::begin() );
376 /// Returns an iterator that addresses the location succeeding the last element in a set
378 Do not use the value returned by <tt>end</tt> function to access any item.
379 The returned value can be used only to control reaching the end of the set.
380 For empty set \code begin() == end() \endcode
384 return iterator( base_class::end() );
387 /// Returns a forward const iterator addressing the first element in a set
388 const_iterator begin() const
390 return const_iterator( base_class::begin() );
393 /// Returns an const iterator that addresses the location succeeding the last element in a set
394 const_iterator end() const
396 return const_iterator( base_class::end() );
402 The function creates a node with copy of \p val value
403 and then inserts the node created into the set.
405 The type \p Q should contain as minimum the complete key for the node.
406 The object of \p value_type should be constructible from a value of type \p Q.
407 In trivial case, \p Q is equal to \p value_type.
409 The function applies RCU lock internally.
411 Returns \p true if \p val is inserted into the set, \p false otherwise.
413 template <typename Q>
414 bool insert( Q const& val )
416 return insert_node( alloc_node( val ) );
421 The function allows to split creating of new item into two part:
422 - create item with key only
423 - insert new item into the set
424 - if inserting is success, calls \p f functor to initialize value-field of \p val.
426 The functor signature is:
428 void func( value_type& val );
430 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
431 \p val no any other changes could be made on this set's item by concurrent threads.
432 The user-defined functor is called only if the inserting is success.
434 The function applies RCU lock internally.
436 template <typename Q, typename Func>
437 bool insert( Q const& key, Func f )
439 scoped_node_ptr pNode( alloc_node( key ));
441 if ( base_class::insert( *pNode, [&f](node_type& node) { f( node.m_Value ) ; } )) {
448 /// Inserts data of type \p value_type created from \p args
450 Returns \p true if inserting successful, \p false otherwise.
452 The function applies RCU lock internally.
454 template <typename... Args>
455 bool emplace( Args&&... args )
457 return insert_node( alloc_node( std::forward<Args>(args)...));
460 /// Ensures that the \p val exists in the set
462 The operation performs inserting or changing data with lock-free manner.
464 If the \p val key not found in the set, then the new item created from \p val
465 is inserted into the set. Otherwise, the functor \p func is called with the item found.
466 The functor \p Func signature is:
469 void operator()( bool bNew, value_type& item, const Q& val );
474 - \p bNew - \p true if the item has been inserted, \p false otherwise
475 - \p item - item of the set
476 - \p val - argument \p val passed into the \p %ensure() function
478 The functor may change non-key fields of the \p item; however, \p func must guarantee
479 that during changing no any other modifications could be made on this item by concurrent threads.
481 The function applies RCU lock internally.
483 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
484 \p second is true if new item has been added or \p false if the item with \p key
485 already is in the set.
487 template <typename Q, typename Func>
488 std::pair<bool, bool> ensure( Q const& val, Func func )
490 scoped_node_ptr pNode( alloc_node( val ));
492 std::pair<bool, bool> bRet = base_class::ensure( *pNode,
493 [&func, &val]( bool bNew, node_type& item, node_type const& /*val*/ ) {
494 func( bNew, item.m_Value, val );
496 if ( bRet.first && bRet.second )
501 /// Deletes \p key from the set
502 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_val
504 Template parameter of type \p Q defines the key type searching in the list.
505 The set item comparator should be able to compare the values of type \p value_type
508 RCU \p synchronize method can be called. RCU should not be locked.
510 Return \p true if key is found and deleted, \p false otherwise
512 template <typename Q>
513 bool erase( Q const& key )
515 return base_class::erase( key );
518 /// Deletes the item from the set using \p pred predicate for searching
520 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_val "erase(Q const&)"
521 but \p pred is used for key comparing.
522 \p Less functor has the interface like \p std::less.
523 \p Less must imply the same element order as the comparator used for building the set.
525 template <typename Q, typename Less>
526 bool erase_with( Q const& key, Less pred )
528 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type() );
531 /// Deletes \p key from the set
532 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_func
534 The function searches an item with key \p key, calls \p f functor
535 and deletes the item. If \p key is not found, the functor is not called.
537 The functor \p Func interface:
540 void operator()(value_type const& val);
544 Template parameter of type \p Q defines the key type searching in the list.
545 The list item comparator should be able to compare the values of the type \p value_type
548 RCU \p synchronize method can be called. RCU should not be locked.
550 Return \p true if key is found and deleted, \p false otherwise
552 template <typename Q, typename Func>
553 bool erase( Q const& key, Func f )
555 return base_class::erase( key, [&f](node_type& node) { f( node.m_Value ); } );
558 /// Deletes the item from the set using \p pred predicate for searching
560 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_func "erase(Q const&, Func)"
561 but \p pred is used for key comparing.
562 \p Less functor has the interface like \p std::less.
563 \p Less must imply the same element order as the comparator used for building the set.
565 template <typename Q, typename Less, typename Func>
566 bool erase_with( Q const& key, Less pred, Func f )
568 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type(),
569 [&f](node_type& node) { f( node.m_Value ); } );
572 /// Extracts an item from the set
573 /** \anchor cds_nonintrusive_SplitListSet_rcu_extract
574 The function searches an item with key equal to \p key in the set,
575 unlinks it from the set, places item pointer into \p dest argument, and returns \p true.
576 If the item with the key equal to \p key is not found the function return \p false.
578 @note The function does NOT call RCU read-side lock or synchronization,
579 and does NOT dispose the item found. It just excludes the item from the set
580 and returns a pointer to item found.
581 You should lock RCU before calling of the function, and you should synchronize RCU
582 outside the RCU lock to free extracted item
585 typedef cds::urcu::gc< general_buffered<> > rcu;
586 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
588 splitlist_set theSet;
591 splitlist_set::exempt_ptr p;
593 // first, we should lock RCU
594 splitlist_set::rcu_lock lock;
596 // Now, you can apply extract function
597 // Note that you must not delete the item found inside the RCU lock
598 if ( theSet.extract( p, 10 )) {
599 // do something with p
604 // We may safely release p here
605 // release() passes the pointer to RCU reclamation cycle
609 template <typename Q>
610 bool extract( exempt_ptr& dest, Q const& key )
612 node_type * pNode = base_class::extract_( key, key_comparator() );
620 /// Extracts an item from the set using \p pred predicate for searching
622 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_extract "extract(exempt_ptr&, Q const&)"
623 but \p pred is used for key comparing.
624 \p Less functor has the interface like \p std::less.
625 \p pred must imply the same element order as the comparator used for building the set.
627 template <typename Q, typename Less>
628 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
630 node_type * pNode = base_class::extract_with_( key, typename maker::template predicate_wrapper<Less>::type());
638 /// Finds the key \p key
639 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_func
641 The function searches the item with key equal to \p key and calls the functor \p f for item found.
642 The interface of \p Func functor is:
645 void operator()( value_type& item, Q& key );
648 where \p item is the item found, \p key is the <tt>find</tt> function argument.
650 The functor may change non-key fields of \p item. Note that the functor is only guarantee
651 that \p item cannot be disposed during functor is executing.
652 The functor does not serialize simultaneous access to the set's \p item. If such access is
653 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
655 Note the hash functor specified for class \p Traits template parameter
656 should accept a parameter of type \p Q that can be not the same as \p value_type.
658 The function makes RCU lock internally.
660 The function returns \p true if \p key is found, \p false otherwise.
662 template <typename Q, typename Func>
663 bool find( Q& key, Func f )
665 return find_( key, f );
668 /// Finds the key \p key using \p pred predicate for searching
670 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_func "find(Q&, Func)"
671 but \p pred is used for key comparing.
672 \p Less functor has the interface like \p std::less.
673 \p Less must imply the same element order as the comparator used for building the set.
675 template <typename Q, typename Less, typename Func>
676 bool find_with( Q& key, Less pred, Func f )
678 return find_with_( key, pred, f );
681 /// Finds the key \p key
682 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_val
684 The function searches the item with key equal to \p key
685 and returns \p true if it is found, and \p false otherwise.
687 Note the hash functor specified for class \p Traits template parameter
688 should accept a parameter of type \p Q that can be not the same as \p value_type.
690 The function makes RCU lock internally.
692 template <typename Q>
693 bool find( Q const& key )
695 return base_class::find( key );
698 /// Finds the key \p key using \p pred predicate for searching
700 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_val "find(Q const&)"
701 but \p pred is used for key comparing.
702 \p Less functor has the interface like \p std::less.
703 \p Less must imply the same element order as the comparator used for building the set.
705 template <typename Q, typename Less>
706 bool find_with( Q const& key, Less pred )
708 return base_class::find_with( key, typename maker::template predicate_wrapper<Less>::type() );
711 /// Finds the key \p key and return the item found
712 /** \anchor cds_nonintrusive_SplitListSet_rcu_get
713 The function searches the item with key equal to \p key and returns the pointer to item found.
714 If \p key is not found it returns \p nullptr.
716 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
718 RCU should be locked before call of this function.
719 Returned item is valid only while RCU is locked:
721 typedef cds::urcu::gc< general_buffered<> > rcu;
722 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
723 splitlist_set theSet;
727 splitlist_set::rcu_lock lock;
729 foo * pVal = theSet.get( 5 );
734 // Unlock RCU by rcu_lock destructor
735 // pVal can be retired by disposer at any time after RCU has been unlocked
739 template <typename Q>
740 value_type * get( Q const& key )
742 node_type * pNode = base_class::get( key );
743 return pNode ? &pNode->m_Value : nullptr;
746 /// Finds the key \p key and return the item found
748 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_get "get(Q const&)"
749 but \p pred is used for comparing the keys.
751 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
753 \p pred must imply the same element order as the comparator used for building the set.
755 template <typename Q, typename Less>
756 value_type * get_with( Q const& key, Less pred )
758 node_type * pNode = base_class::get_with( key, typename maker::template predicate_wrapper<Less>::type());
759 return pNode ? &pNode->m_Value : nullptr;
762 /// Clears the set (not atomic)
768 /// Checks if the set is empty
770 Emptiness is checked by item counting: if item count is zero then assume that the set is empty.
771 Thus, the correct item counting feature is an important part of split-list set implementation.
775 return base_class::empty();
778 /// Returns item count in the set
781 return base_class::size();
784 }} // namespace cds::container
786 #endif // #ifndef __CDS_CONTAINER_SPLIT_LIST_SET_RCU_H