3 #ifndef CDSLIB_CONTAINER_SPLIT_LIST_SET_RCU_H
4 #define CDSLIB_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/urcu/exempt_ptr.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 \p 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 of the value to be stored in the split-list.
25 - \p Traits - type traits, default is \p split_list::traits. Instead of declaring \p split_list::traits -based
26 struct you can apply option-based notation with \p split_list::make_traits metafunction.
30 The class supports a forward iterator (\ref iterator and \ref const_iterator).
31 The iteration is unordered.
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 @warning The iterator object cannot be passed between threads
39 \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate
40 all elements in the set: any concurrent deletion can exclude the element
41 pointed by the iterator from the set, and your iteration can be terminated
42 before end of the set. Therefore, such iteration is more suitable for debugging purposes
44 The iterator class supports the following minimalistic interface:
51 iterator( iterator const& s);
53 value_type * operator ->() const;
54 value_type& operator *() const;
57 iterator& operator ++();
60 iterator& operator = (const iterator& src);
62 bool operator ==(iterator const& i ) const;
63 bool operator !=(iterator const& i ) const;
66 Note, the iterator object returned by \p end(), \p cend() member functions points to \p nullptr and should not be dereferenced.
70 You should decide what garbage collector you want, and what ordered list you want to use. Split-ordered list
71 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
72 and \p LazyList as ordered list implementation. So, you beginning your program with following include:
74 #include <cds/urcu/general_buffered.h>
75 #include <cds/container/lazy_list_rcu.h>
76 #include <cds/container/split_list_set_rcu.h>
78 namespace cc = cds::container;
80 // The data belonged to split-ordered list
82 int nKey; // key field
83 std::string strValue ; // value field
86 The inclusion order is important:
87 - first, include one of \ref cds_urcu_gc "RCU implementation" (<tt>cds/urcu/general_buffered.h</tt> in our case)
88 - second, include file for ordered-list implementation (for this example, <tt>cds/container/lazy_list_rcu.h</tt>),
89 - then, the header for RCU-based split-list set <tt>cds/container/split_list_set_rcu.h</tt>.
91 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.
92 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
93 object by the key of type \p int and by the value of type \p foo.
95 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.
96 The split-list requires significant support from underlying ordered list class and it is not good idea to dive you
97 into deep implementation details of split-list and ordered list interrelations. The tag paradigm simplifies split-list interface.
102 size_t operator()( int key ) const { return std::hash( key ) ; }
103 size_t operator()( foo const& item ) const { return std::hash( item.nKey ) ; }
108 bool operator()(int i, foo const& f ) const { return i < f.nKey ; }
109 bool operator()(foo const& f, int i ) const { return f.nKey < i ; }
110 bool operator()(foo const& f1, foo const& f2) const { return f1.nKey < f2.nKey; }
113 // SplitListSet traits
114 struct foo_set_traits: public cc::split_list::traits
116 typedef cc::lazy_list_tag ordered_list ; // what type of ordered list we want to use
117 typedef foo_hash hash ; // hash functor for our data stored in split-list set
119 // Type traits for our LazyList class
120 struct ordered_list_traits: public cc::lazy_list::traits
122 typedef foo_less less ; // use our foo_less as comparator to order list nodes
127 Now you are ready to declare our set class based on \p %SplitListSet:
129 typedef cc::SplitListSet< cds::urcu::gc<cds::urcu::general_buffered<> >, foo, foo_set_traits > foo_set;
132 You may use the modern option-based declaration instead of classic type-traits-based one:
134 typedef cc:SplitListSet<
135 cds::urcu::gc<cds::urcu::general_buffered<> > // RCU type used
136 ,foo // type of data stored
137 ,cc::split_list::make_traits< // metafunction to build split-list traits
138 cc::split_list::ordered_list<cc::lazy_list_tag> // tag for underlying ordered list implementation
139 ,cc::opt::hash< foo_hash > // hash functor
140 ,cc::split_list::ordered_list_traits< // ordered list traits
141 cc::lazy_list::make_traits< // metafunction to build lazy list traits
142 cc::opt::less< foo_less > // less-based compare functor
148 In case of option-based declaration using \p split_list::make_traits metafunction
149 the struct \p foo_set_traits is not required.
151 Now, the set of type \p foo_set is ready to use in your program.
153 Note that in this example we show only mandatory \p traits parts, optional ones is the default and they are inherited
154 from \p container::split_list::traits.
155 There are many other options for deep tuning of the split-list and ordered-list containers.
160 #ifdef CDS_DOXYGEN_INVOKED
161 class Traits = split_list::traits
166 class SplitListSet< cds::urcu::gc< RCU >, T, Traits >:
167 #ifdef CDS_DOXYGEN_INVOKED
168 protected intrusive::SplitListSet< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, Traits >
170 protected details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> >::type
175 typedef details::make_split_list_set< cds::urcu::gc< RCU >, T, typename Traits::ordered_list, split_list::details::wrap_set_traits<T, Traits> > maker;
176 typedef typename maker::type base_class;
180 typedef cds::urcu::gc< RCU > gc; ///< RCU-based garbage collector
181 typedef T value_type; ///< Type of value to be storedin the set
182 typedef Traits traits; ///< \p Traits template argument
184 typedef typename maker::ordered_list ordered_list; ///< Underlying ordered list class
185 typedef typename base_class::key_comparator key_comparator; ///< key compare functor
187 /// Hash functor for \ref value_type and all its derivatives that you use
188 typedef typename base_class::hash hash;
189 typedef typename base_class::item_counter item_counter; ///< Item counter type
190 typedef typename base_class::stat stat; ///< Internal statistics
192 typedef typename base_class::rcu_lock rcu_lock ; ///< RCU scoped lock
193 /// Group of \p extract_xxx functions require external locking if underlying ordered list requires that
194 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal;
197 typedef cds::container::split_list::implementation_tag implementation_tag;
202 typedef typename maker::cxx_node_allocator cxx_node_allocator;
203 typedef typename maker::node_type node_type;
207 /// pointer to extracted node
208 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::ordered_list_traits::disposer >;
212 template <typename Q, typename Func>
213 bool find_( Q& val, Func f )
215 return base_class::find( val, [&f]( node_type& item, Q& val ) { f(item.m_Value, val) ; } );
218 template <typename Q, typename Less, typename Func>
219 bool find_with_( Q& val, Less pred, Func f )
222 return base_class::find_with( val, typename maker::template predicate_wrapper<Less>::type(),
223 [&f]( node_type& item, Q& val ) { f(item.m_Value, val) ; } );
226 template <typename Q>
227 static node_type * alloc_node( Q const& v )
229 CDS_TSAN_ANNOTATE_IGNORE_WRITES_BEGIN;
230 node_type * p = cxx_node_allocator().New( v );
231 CDS_TSAN_ANNOTATE_IGNORE_WRITES_END;
235 template <typename... Args>
236 static node_type * alloc_node( Args&&... args )
238 CDS_TSAN_ANNOTATE_IGNORE_WRITES_BEGIN;
239 node_type * p = cxx_node_allocator().MoveNew( std::forward<Args>(args)...);
240 CDS_TSAN_ANNOTATE_IGNORE_WRITES_END;
244 static void free_node( node_type * pNode )
246 CDS_TSAN_ANNOTATE_IGNORE_WRITES_BEGIN;
247 cxx_node_allocator().Delete( pNode );
248 CDS_TSAN_ANNOTATE_IGNORE_WRITES_END;
251 struct node_disposer {
252 void operator()( node_type * pNode )
257 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
259 bool insert_node( node_type * pNode )
261 assert( pNode != nullptr );
262 scoped_node_ptr p(pNode);
264 if ( base_class::insert( *pNode ) ) {
276 \p IsConst - constness boolean flag
278 The forward iterator for a split-list has the following features:
279 - it has no post-increment operator
280 - it depends on underlying ordered list iterator
281 - it is safe to iterate only inside RCU critical section
282 - deleting an item pointed by the iterator can cause to deadlock
284 Therefore, the use of iterators in concurrent environment is not good idea.
285 Use it for debug purpose only.
287 template <bool IsConst>
288 class iterator_type: protected base_class::template iterator_type<IsConst>
291 typedef typename base_class::template iterator_type<IsConst> iterator_base_class;
292 friend class SplitListSet;
295 /// Value pointer type (const for const iterator)
296 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
297 /// Value reference type (const for const iterator)
298 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
306 iterator_type( iterator_type const& src )
307 : iterator_base_class( src )
312 explicit iterator_type( iterator_base_class const& src )
313 : iterator_base_class( src )
318 /// Dereference operator
319 value_ptr operator ->() const
321 return &(iterator_base_class::operator->()->m_Value);
324 /// Dereference operator
325 value_ref operator *() const
327 return iterator_base_class::operator*().m_Value;
331 iterator_type& operator ++()
333 iterator_base_class::operator++();
337 /// Assignment operator
338 iterator_type& operator = (iterator_type const& src)
340 iterator_base_class::operator=(src);
344 /// Equality operator
346 bool operator ==(iterator_type<C> const& i ) const
348 return iterator_base_class::operator==(i);
351 /// Equality operator
353 bool operator !=(iterator_type<C> const& i ) const
355 return iterator_base_class::operator!=(i);
360 /// Initializes split-ordered list of default capacity
362 The default capacity is defined in bucket table constructor.
363 See \p intrusive::split_list::expandable_bucket_table, \p intrusive::split_list::static_bucket_table
364 which selects by \p container::split_list::dynamic_bucket_table option.
370 /// Initializes split-ordered list
372 size_t nItemCount ///< estimated average of item count
373 , size_t nLoadFactor = 1 ///< load factor - average item count per bucket. Small integer up to 8, default is 1.
375 : base_class( nItemCount, nLoadFactor )
379 typedef iterator_type<false> iterator ; ///< Forward iterator
380 typedef iterator_type<true> const_iterator ; ///< Forward const iterator
382 /// Returns a forward iterator addressing the first element in a set
384 For empty set \code begin() == end() \endcode
388 return iterator( base_class::begin() );
391 /// Returns an iterator that addresses the location succeeding the last element in a set
393 Do not use the value returned by <tt>end</tt> function to access any item.
394 The returned value can be used only to control reaching the end of the set.
395 For empty set \code begin() == end() \endcode
399 return iterator( base_class::end() );
402 /// Returns a forward const iterator addressing the first element in a set
403 const_iterator begin() const
407 /// Returns a forward const iterator addressing the first element in a set
408 const_iterator cbegin() const
410 return const_iterator( base_class::cbegin() );
413 /// Returns an const iterator that addresses the location succeeding the last element in a set
414 const_iterator end() const
418 /// Returns an const iterator that addresses the location succeeding the last element in a set
419 const_iterator cend() const
421 return const_iterator( base_class::cend() );
427 The function creates a node with copy of \p val value
428 and then inserts the node created into the set.
430 The type \p Q should contain as minimum the complete key for the node.
431 The object of \p value_type should be constructible from a value of type \p Q.
432 In trivial case, \p Q is equal to \p value_type.
434 The function applies RCU lock internally.
436 Returns \p true if \p val is inserted into the set, \p false otherwise.
438 template <typename Q>
439 bool insert( Q const& val )
441 return insert_node( alloc_node( val ) );
446 The function allows to split creating of new item into two part:
447 - create item with key only
448 - insert new item into the set
449 - if inserting is success, calls \p f functor to initialize value-field of \p val.
451 The functor signature is:
453 void func( value_type& val );
455 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
456 \p val no any other changes could be made on this set's item by concurrent threads.
457 The user-defined functor is called only if the inserting is success.
459 The function applies RCU lock internally.
461 template <typename Q, typename Func>
462 bool insert( Q const& key, Func f )
464 scoped_node_ptr pNode( alloc_node( key ));
466 if ( base_class::insert( *pNode, [&f](node_type& node) { f( node.m_Value ) ; } )) {
473 /// Inserts data of type \p value_type created from \p args
475 Returns \p true if inserting successful, \p false otherwise.
477 The function applies RCU lock internally.
479 template <typename... Args>
480 bool emplace( Args&&... args )
482 return insert_node( alloc_node( std::forward<Args>(args)...));
485 /// Ensures that the \p val exists in the set
487 The operation performs inserting or changing data with lock-free manner.
489 If the \p val key not found in the set, then the new item created from \p val
490 is inserted into the set. Otherwise, the functor \p func is called with the item found.
491 The functor \p Func signature is:
494 void operator()( bool bNew, value_type& item, const Q& val );
499 - \p bNew - \p true if the item has been inserted, \p false otherwise
500 - \p item - item of the set
501 - \p val - argument \p val passed into the \p %ensure() function
503 The functor may change non-key fields of the \p item; however, \p func must guarantee
504 that during changing no any other modifications could be made on this item by concurrent threads.
506 The function applies RCU lock internally.
508 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
509 \p second is true if new item has been added or \p false if the item with \p key
510 already is in the set.
512 template <typename Q, typename Func>
513 std::pair<bool, bool> ensure( Q const& val, Func func )
515 scoped_node_ptr pNode( alloc_node( val ));
517 std::pair<bool, bool> bRet = base_class::ensure( *pNode,
518 [&func, &val]( bool bNew, node_type& item, node_type const& /*val*/ ) {
519 func( bNew, item.m_Value, val );
521 if ( bRet.first && bRet.second )
526 /// Deletes \p key from the set
527 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_val
529 Template parameter of type \p Q defines the key type searching in the list.
530 The set item comparator should be able to compare the values of type \p value_type
533 RCU \p synchronize method can be called. RCU should not be locked.
535 Return \p true if key is found and deleted, \p false otherwise
537 template <typename Q>
538 bool erase( Q const& key )
540 return base_class::erase( key );
543 /// Deletes the item from the set using \p pred predicate for searching
545 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_val "erase(Q const&)"
546 but \p pred is used for key comparing.
547 \p Less functor has the interface like \p std::less.
548 \p Less must imply the same element order as the comparator used for building the set.
550 template <typename Q, typename Less>
551 bool erase_with( Q const& key, Less pred )
554 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type() );
557 /// Deletes \p key from the set
558 /** \anchor cds_nonintrusive_SplitListSet_rcu_erase_func
560 The function searches an item with key \p key, calls \p f functor
561 and deletes the item. If \p key is not found, the functor is not called.
563 The functor \p Func interface:
566 void operator()(value_type const& val);
570 Template parameter of type \p Q defines the key type searching in the list.
571 The list item comparator should be able to compare the values of the type \p value_type
574 RCU \p synchronize method can be called. RCU should not be locked.
576 Return \p true if key is found and deleted, \p false otherwise
578 template <typename Q, typename Func>
579 bool erase( Q const& key, Func f )
581 return base_class::erase( key, [&f](node_type& node) { f( node.m_Value ); } );
584 /// Deletes the item from the set using \p pred predicate for searching
586 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_erase_func "erase(Q const&, Func)"
587 but \p pred is used for key comparing.
588 \p Less functor has the interface like \p std::less.
589 \p Less must imply the same element order as the comparator used for building the set.
591 template <typename Q, typename Less, typename Func>
592 bool erase_with( Q const& key, Less pred, Func f )
595 return base_class::erase_with( key, typename maker::template predicate_wrapper<Less>::type(),
596 [&f](node_type& node) { f( node.m_Value ); } );
599 /// Extracts an item from the set
600 /** \anchor cds_nonintrusive_SplitListSet_rcu_extract
601 The function searches an item with key equal to \p key in the set,
602 unlinks it from the set, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
603 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
605 @note The function does NOT call RCU read-side lock or synchronization,
606 and does NOT dispose the item found. It just excludes the item from the set
607 and returns a pointer to item found.
608 You should lock RCU before calling of the function, and you should synchronize RCU
609 outside the RCU lock to free extracted item
612 typedef cds::urcu::gc< general_buffered<> > rcu;
613 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
615 splitlist_set theSet;
618 splitlist_set::exempt_ptr p;
620 // first, we should lock RCU
621 splitlist_set::rcu_lock lock;
623 // Now, you can apply extract function
624 // Note that you must not delete the item found inside the RCU lock
625 p = theSet.extract( 10 );
627 // do something with p
632 // We may safely release p here
633 // release() passes the pointer to RCU reclamation cycle
637 template <typename Q>
638 exempt_ptr extract( Q const& key )
640 return exempt_ptr( base_class::extract_( key, key_comparator() ));
643 /// Extracts an item from the set using \p pred predicate for searching
645 The function is an analog of \p extract(Q const&) but \p pred is used for key comparing.
646 \p Less functor has the interface like \p std::less.
647 \p pred must imply the same element order as the comparator used for building the set.
649 template <typename Q, typename Less>
650 exempt_ptr extract_with( Q const& key, Less pred )
653 return exempt_ptr( base_class::extract_with_( key, typename maker::template predicate_wrapper<Less>::type()));
656 /// Finds the key \p key
657 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_func
659 The function searches the item with key equal to \p key and calls the functor \p f for item found.
660 The interface of \p Func functor is:
663 void operator()( value_type& item, Q& key );
666 where \p item is the item found, \p key is the <tt>find</tt> function argument.
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 Note the hash functor specified for class \p Traits template parameter
674 should accept a parameter of type \p Q that can be not the same as \p value_type.
676 The function makes RCU lock internally.
678 The function returns \p true if \p key is found, \p false otherwise.
680 template <typename Q, typename Func>
681 bool find( Q& key, Func f )
683 return find_( key, f );
686 template <typename Q, typename Func>
687 bool find( Q const& key, Func f )
689 return find_( key, f );
693 /// Finds the key \p key using \p pred predicate for searching
695 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_func "find(Q&, Func)"
696 but \p pred is used for key comparing.
697 \p Less functor has the interface like \p std::less.
698 \p Less must imply the same element order as the comparator used for building the set.
700 template <typename Q, typename Less, typename Func>
701 bool find_with( Q& key, Less pred, Func f )
703 return find_with_( key, pred, f );
706 template <typename Q, typename Less, typename Func>
707 bool find_with( Q const& key, Less pred, Func f )
709 return find_with_( key, pred, f );
713 /// Finds the key \p key
714 /** \anchor cds_nonintrusive_SplitListSet_rcu_find_val
716 The function searches the item with key equal to \p key
717 and returns \p true if it is found, and \p false otherwise.
719 Note the hash functor specified for class \p Traits template parameter
720 should accept a parameter of type \p Q that can be not the same as \p value_type.
722 The function makes RCU lock internally.
724 template <typename Q>
725 bool find( Q const& key )
727 return base_class::find( key );
730 /// Finds the key \p key using \p pred predicate for searching
732 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_find_val "find(Q const&)"
733 but \p pred is used for key comparing.
734 \p Less functor has the interface like \p std::less.
735 \p Less must imply the same element order as the comparator used for building the set.
737 template <typename Q, typename Less>
738 bool find_with( Q const& key, Less pred )
741 return base_class::find_with( key, typename maker::template predicate_wrapper<Less>::type() );
744 /// Finds the key \p key and return the item found
745 /** \anchor cds_nonintrusive_SplitListSet_rcu_get
746 The function searches the item with key equal to \p key and returns the pointer to item found.
747 If \p key is not found it returns \p nullptr.
749 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
751 RCU should be locked before call of this function.
752 Returned item is valid only while RCU is locked:
754 typedef cds::urcu::gc< general_buffered<> > rcu;
755 typedef cds::container::SplitListSet< rcu, Foo > splitlist_set;
756 splitlist_set theSet;
760 splitlist_set::rcu_lock lock;
762 foo * pVal = theSet.get( 5 );
767 // Unlock RCU by rcu_lock destructor
768 // pVal can be retired by disposer at any time after RCU has been unlocked
772 template <typename Q>
773 value_type * get( Q const& key )
775 node_type * pNode = base_class::get( key );
776 return pNode ? &pNode->m_Value : nullptr;
779 /// Finds the key \p key and return the item found
781 The function is an analog of \ref cds_nonintrusive_SplitListSet_rcu_get "get(Q const&)"
782 but \p pred is used for comparing the keys.
784 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
786 \p pred must imply the same element order as the comparator used for building the set.
788 template <typename Q, typename Less>
789 value_type * get_with( Q const& key, Less pred )
792 node_type * pNode = base_class::get_with( key, typename maker::template predicate_wrapper<Less>::type());
793 return pNode ? &pNode->m_Value : nullptr;
796 /// Clears the set (not atomic)
802 /// Checks if the set is empty
804 Emptiness is checked by item counting: if item count is zero then assume that the set is empty.
805 Thus, the correct item counting feature is an important part of split-list set implementation.
809 return base_class::empty();
812 /// Returns item count in the set
815 return base_class::size();
818 /// Returns internal statistics
819 stat const& statistics() const
821 return base_class::statistics();
824 }} // namespace cds::container
826 #endif // #ifndef CDSLIB_CONTAINER_SPLIT_LIST_SET_RCU_H