2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_CONTAINER_IMPL_ITERABLE_LIST_H
32 #define CDSLIB_CONTAINER_IMPL_ITERABLE_LIST_H
34 #include <cds/container/details/make_iterable_list.h>
37 namespace cds { namespace container {
39 /// Iterable ordered list
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_IterableList_gc
43 This lock-free list implementation supports thread-safe iterators.
45 Usually, ordered single-linked list is used as a building block for the hash table implementation.
46 Iterable list is suitable for almost append-only hash table because the list doesn't delete
47 its internal node when erasing a key but it is marked them as empty to be reused in the future.
48 However, plenty of empty nodes degrades performance.
50 The complexity of searching is <tt>O(N)</tt>.
53 - \p GC - Garbage collector used.
54 - \p T - type to be stored in the list.
55 - \p Traits - type traits, default is \p iterable_list::traits.
57 Unlike standard container, this implementation does not divide type \p T into key and value part and
58 may be used as a main building block for hash set algorithms.
59 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
60 or <tt>Traits::less</tt> predicate.
62 \p IterableKVList is a key-value version of iterable non-intrusive list that is closer to the C++ std library approach.
64 It is possible to declare option-based list with cds::container::iterable_list::make_traits metafunction istead of \p Traits template
65 argument. For example, the following traits-based declaration of gc::HP iterable list
67 #include <cds/container/iterable_list_hp.h>
68 // Declare comparator for the item
70 int operator ()( int i1, int i2 )
77 struct my_traits: public cds::container::iterable_list::traits
79 typedef my_compare compare;
82 // Declare traits-based list
83 typedef cds::container::IterableList< cds::gc::HP, int, my_traits > traits_based_list;
86 is equivalent for the following option-based list
88 #include <cds/container/iterable_list_hp.h>
90 // my_compare is the same
92 // Declare option-based list
93 typedef cds::container::IterableList< cds::gc::HP, int,
94 typename cds::container::iterable_list::make_traits<
95 cds::container::opt::compare< my_compare > // item comparator option
101 There are different specializations of this template for each garbage collecting schema used.
102 You should include appropriate .h-file depending on GC you are using:
103 - for gc::HP: \code #include <cds/container/iterable_list_hp.h> \endcode
104 - for gc::DHP: \code #include <cds/container/iterable_list_dhp.h> \endcode
105 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/iterable_list_rcu.h> \endcode
110 #ifdef CDS_DOXYGEN_INVOKED
111 typename Traits = iterable_list::traits
117 #ifdef CDS_DOXYGEN_INVOKED
118 protected intrusive::IterableList< GC, T, Traits >
120 protected details::make_iterable_list< GC, T, Traits >::type
124 typedef details::make_iterable_list< GC, T, Traits > maker;
125 typedef typename maker::type base_class;
129 typedef T value_type; ///< Type of value stored in the list
130 typedef Traits traits; ///< List traits
132 typedef typename base_class::gc gc; ///< Garbage collector used
133 typedef typename base_class::back_off back_off; ///< Back-off strategy used
134 typedef typename maker::data_allocator_type allocator_type; ///< Allocator type used for allocate/deallocate data
135 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
136 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
137 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See \p cds::opt::memory_model option
138 typedef typename base_class::stat stat; ///< Internal statistics
140 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
143 // Rebind traits (split-list support)
144 template <typename... Options>
145 struct rebind_traits {
146 typedef IterableList<
149 , typename cds::opt::make_options< traits, Options...>::type
154 template <typename Stat>
155 using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
160 typedef typename maker::cxx_data_allocator cxx_data_allocator;
161 typedef typename maker::data_disposer data_disposer;
162 typedef typename base_class::node_type head_type;
167 typedef typename base_class::guarded_ptr guarded_ptr;
171 template <bool IsConst>
172 class iterator_type: protected base_class::template iterator_type<IsConst>
174 typedef typename base_class::template iterator_type<IsConst> iterator_base;
175 friend class IterableList;
177 iterator_type( iterator_base it )
178 : iterator_base( it )
182 typedef typename iterator_base::value_ptr value_ptr;
183 typedef typename iterator_base::value_ref value_ref;
188 iterator_type( iterator_type const& src )
189 : iterator_base( src )
192 value_ptr operator ->() const
194 return iterator_base::operator ->();
197 value_ref operator *() const
199 return iterator_base::operator *();
203 iterator_type& operator ++()
205 iterator_base::operator ++();
210 bool operator ==(iterator_type<C> const& i ) const
212 return iterator_base::operator ==(i);
215 bool operator !=(iterator_type<C> const& i ) const
217 return iterator_base::operator !=(i);
223 ///@name Thread-safe forward iterators
227 The forward iterator for iterable list has some features:
228 - it has no post-increment operator
229 - to protect the value, the iterator contains a GC-specific guard.
230 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
231 may be thrown if the limit of guard count per thread is exceeded.
232 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
233 - Iterator is thread-safe: even if an element the iterator points to is removed, the iterator stays valid because
234 it contains the guard keeping the value from to be recycled.
236 The iterator interface:
240 // Default constructor
244 iterator( iterator const& src );
246 // Dereference operator
247 value_type * operator ->() const;
249 // Dereference operator
250 value_type& operator *() const;
252 // Preincrement operator
253 iterator& operator ++();
255 // Assignment operator
256 iterator& operator = (iterator const& src);
258 // Equality operators
259 bool operator ==(iterator const& i ) const;
260 bool operator !=(iterator const& i ) const;
264 @note For two iterators pointed to the same element the value can be different;
268 assert( &(*it1) == &(*it2));
270 can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread.
271 The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing.
272 Other iterator can observe modified value of the element.
274 typedef iterator_type<false> iterator;
276 /// Const forward iterator
278 For iterator's features and requirements see \ref iterator
280 typedef iterator_type<true> const_iterator;
282 /// Returns a forward iterator addressing the first element in a list
284 For empty list \code begin() == end() \endcode
288 return iterator( base_class::begin());
291 /// Returns an iterator that addresses the location succeeding the last element in a list
293 Do not use the value returned by <tt>end</tt> function to access any item.
294 Internally, <tt>end</tt> returning value equals to \p nullptr.
296 The returned value can be used only to control reaching the end of the list.
297 For empty list \code begin() == end() \endcode
301 return iterator( base_class::end());
304 /// Returns a forward const iterator addressing the first element in a list
305 const_iterator begin() const
307 return const_iterator( base_class::cbegin());
310 /// Returns a forward const iterator addressing the first element in a list
311 const_iterator cbegin() const
313 return const_iterator( base_class::cbegin());
316 /// Returns an const iterator that addresses the location succeeding the last element in a list
317 const_iterator end() const
319 return const_iterator( base_class::cend());
322 /// Returns an const iterator that addresses the location succeeding the last element in a list
323 const_iterator cend() const
325 return const_iterator( base_class::cend());
330 /// Default constructor
332 Initialize empty list
338 template <typename Stat, typename = std::enable_if<std::is_same<stat, iterable_list::wrapped_stat<Stat>>::value >>
339 explicit IterableList( Stat& st )
353 The function creates a node with copy of \p val value
354 and then inserts the node created into the list.
356 The type \p Q should contain least the complete key of the node.
357 The object of \ref value_type should be constructible from \p val of type \p Q.
358 In trivial case, \p Q is equal to \ref value_type.
360 Returns \p true if inserting successful, \p false otherwise.
362 template <typename Q>
363 bool insert( Q&& val )
365 return insert_at( head(), std::forward<Q>( val ));
370 This function inserts new node with default-constructed value and then it calls
371 \p func functor with signature
373 void func( value_type& data );
376 The argument \p data of user-defined functor \p func is the reference
377 to the list's item inserted. User-defined functor \p func should guarantee that during changing
378 item's value no any other changes could be made on this list's item by concurrent threads.
379 The user-defined functor is called only if inserting is success.
381 The type \p Q should contain the complete key of the node.
382 The object of \p value_type should be constructible from \p key of type \p Q.
384 The function allows to split creating of new item into two part:
385 - create item from \p key with initializing key-fields only;
386 - insert new item into the list;
387 - if inserting is successful, initialize non-key fields of item by calling \p func functor
389 The method can be useful if complete initialization of object of \p value_type is heavyweight and
390 it is preferable that the initialization should be completed only if inserting is successful.
392 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
394 template <typename Q, typename Func>
395 bool insert( Q&& key, Func func )
397 return insert_at( head(), std::forward<Q>( key ), func );
400 /// Updates data by \p key
402 The operation performs inserting or replacing the element with lock-free manner.
404 If the \p key not found in the list, then the new item created from \p key
405 will be inserted iff \p bAllowInsert is \p true.
406 Otherwise, if \p key is found, the functor \p func is called with item found.
408 The functor \p func is called after inserting or replacing, it signature is:
410 void func( value_type& val, value_type * old );
413 - \p val - a new data constructed from \p key
414 - \p old - old value that will be retired. If new item has been inserted then \p old is \p nullptr.
416 The functor may change non-key fields of \p val; however, \p func must guarantee
417 that during changing no any other modifications could be made on this item by concurrent threads.
419 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
420 \p second is true if new item has been added or \p false if the item with such \p key
423 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
425 template <typename Q, typename Func>
426 std::pair<bool, bool> update( Q&& key, Func func, bool bAllowInsert = true )
428 return update_at( head(), std::forward<Q>( key ), func, bAllowInsert );
433 The operation performs inserting or updating data with lock-free manner.
435 If the item \p key is not found in the list, then \p key is inserted
436 iff \p bInsert is \p true.
437 Otherwise, the current element is changed to \p key, the old element will be retired later.
439 \p value_type should be constructible from \p key.
441 Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
442 \p second is \p true if \p key has been added or \p false if the item with that key
445 template <typename Q>
446 std::pair<bool, bool> upsert( Q&& key, bool bInsert = true )
448 return update_at( head(), std::forward<Q>( key ), []( value_type&, value_type* ) {}, bInsert );
451 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
453 Returns \p true if inserting successful, \p false otherwise.
455 template <typename... Args>
456 bool emplace( Args&&... args )
458 return emplace_at( head(), std::forward<Args>(args)... );
461 /// Delete \p key from the list
463 Since the key of IterableList's item type \p value_type is not explicitly specified,
464 template parameter \p Q sould contain the complete key to search in the list.
465 The list item comparator should be able to compare the type \p value_type
468 Return \p true if key is found and deleted, \p false otherwise
470 template <typename Q>
471 bool erase( Q const& key )
473 return erase_at( head(), key, key_comparator(), [](value_type const&){} );
476 /// Deletes the item from the list using \p pred predicate for searching
478 The function is an analog of \p erase(Q const&) but \p pred is used for key comparing.
479 \p Less functor has the interface like \p std::less.
480 \p pred must imply the same element order as the comparator used for building the list.
482 template <typename Q, typename Less>
483 bool erase_with( Q const& key, Less pred )
486 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
489 /// Deletes \p key from the list
491 The function searches an item with key \p key, calls \p f functor with item found
492 and deletes it. If \p key is not found, the functor is not called.
494 The functor \p Func interface:
497 void operator()(const value_type& val) { ... }
501 Since the key of IterableList's item type \p value_type is not explicitly specified,
502 template parameter \p Q should contain the complete key to search in the list.
503 The list item comparator should be able to compare the type \p value_type of list item
506 Return \p true if key is found and deleted, \p false otherwise
508 template <typename Q, typename Func>
509 bool erase( Q const& key, Func f )
511 return erase_at( head(), key, key_comparator(), f );
514 /// Deletes the item from the list using \p pred predicate for searching
516 The function is an analog of \p erase(Q const&, Func) but \p pred is used for key comparing.
517 \p Less functor has the interface like \p std::less.
518 \p pred must imply the same element order as the comparator used for building the list.
520 template <typename Q, typename Less, typename Func>
521 bool erase_with( Q const& key, Less pred, Func f )
524 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
527 /// Extracts the item from the list with specified \p key
529 The function searches an item with key equal to \p key,
530 unlinks it from the list, and returns it as \p guarded_ptr.
531 If \p key is not found the function returns an empty guarded pointer.
533 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
535 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
539 typedef cds::container::IterableList< cds::gc::HP, foo, my_traits > ord_list;
543 ord_list::guarded_ptr gp(theList.extract( 5 ));
548 // Destructor of gp releases internal HP guard and frees the item
552 template <typename Q>
553 guarded_ptr extract( Q const& key )
555 return extract_at( head(), key, key_comparator());
558 /// Extracts the item from the list with comparing functor \p pred
560 The function is an analog of \p extract(Q const&) but \p pred predicate is used for key comparing.
562 \p Less functor has the semantics like \p std::less but it should accept arguments
563 of type \p value_type and \p Q in any order.
564 \p pred must imply the same element order as the comparator used for building the list.
566 template <typename Q, typename Less>
567 guarded_ptr extract_with( Q const& key, Less pred )
570 return extract_at( head(), key, typename maker::template less_wrapper<Less>::type());
573 /// Checks whether the list contains \p key
575 The function searches the item with key equal to \p key
576 and returns \p true if it is found, and \p false otherwise.
578 template <typename Q>
579 bool contains( Q const& key ) const
581 return find_at( head(), key, key_comparator());
584 /// Checks whether the list contains \p key using \p pred predicate for searching
586 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
587 \p Less functor has the interface like \p std::less.
588 \p pred must imply the same element order as the comparator used for building the list.
590 template <typename Q, typename Less>
591 bool contains( Q const& key, Less pred ) const
594 return find_at( head(), key, typename maker::template less_wrapper<Less>::type());
597 /// Finds \p key and perform an action with it
599 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
600 The interface of \p Func functor is:
603 void operator()( value_type& item, Q& key );
606 where \p item is the item found, \p key is the <tt>find</tt> function argument.
608 The functor may change non-key fields of \p item. Note that the function is only guarantee
609 that \p item cannot be deleted during functor is executing.
610 The function does not serialize simultaneous access to the list \p item. If such access is
611 possible you must provide your own synchronization schema to exclude unsafe item modifications.
613 The function returns \p true if \p key is found, \p false otherwise.
615 template <typename Q, typename Func>
616 bool find( Q& key, Func f ) const
618 return find_at( head(), key, key_comparator(), f );
621 template <typename Q, typename Func>
622 bool find( Q const& key, Func f ) const
624 return find_at( head(), key, key_comparator(), f );
628 /// Finds \p key in the list and returns iterator pointed to the item found
630 If \p key is not found the function returns \p end().
632 template <typename Q>
633 iterator find( Q const& key ) const
635 return find_iterator_at( head(), key, key_comparator());
638 /// Finds \p key using \p pred predicate for searching
640 The function is an analog of \p find(Q&, Func) but \p pred is used for key comparing.
641 \p Less functor has the interface like \p std::less.
642 \p pred must imply the same element order as the comparator used for building the list.
644 template <typename Q, typename Less, typename Func>
645 bool find_with( Q& key, Less pred, Func f ) const
648 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
651 template <typename Q, typename Less, typename Func>
652 bool find_with( Q const& key, Less pred, Func f ) const
655 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
659 /// Finds \p key in the list using \p pred predicate for searching and returns iterator pointed to the item found
661 The function is an analog of \p find(Q&) but \p pred is used for key comparing.
662 \p Less functor has the interface like \p std::less.
663 \p pred must imply the same element order as the comparator used for building the list.
665 If \p key is not found the function returns \p end().
667 template <typename Q, typename Less>
668 iterator find_with( Q const& key, Less pred ) const
671 return find_iterator_at( head(), key, cds::opt::details::make_comparator_from_less<Less>());
674 /// Finds \p key and return the item found
675 /** \anchor cds_nonintrusive_MichaelList_hp_get
676 The function searches the item with key equal to \p key
677 and returns it as \p guarded_ptr.
678 If \p key is not found the function returns an empty guarded pointer.
680 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
684 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
688 ord_list::guarded_ptr gp(theList.get( 5 ));
693 // Destructor of guarded_ptr releases internal HP guard and frees the item
697 Note the compare functor specified for class \p Traits template parameter
698 should accept a parameter of type \p Q that can be not the same as \p value_type.
700 template <typename Q>
701 guarded_ptr get( Q const& key ) const
703 return get_at( head(), key, key_comparator());
706 /// Finds \p key and return the item found
708 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
709 but \p pred is used for comparing the keys.
711 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
713 \p pred must imply the same element order as the comparator used for building the list.
715 template <typename Q, typename Less>
716 guarded_ptr get_with( Q const& key, Less pred ) const
719 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
722 /// Checks if the list is empty
724 Emptiness is checked by item counting: if item count is zero then the set is empty.
725 Thus, if you need to use \p %empty() you should provide appropriate (non-empty) \p iterable_list::traits::item_counter
730 return base_class::empty();
733 /// Returns list's item count
735 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
736 this function always returns 0.
740 return base_class::size();
743 /// Clears the list (thread safe, not atomic)
749 /// Returns const reference to internal statistics
750 stat const& statistics() const
752 return base_class::statistics();
757 template <typename... Args>
758 static value_type* alloc_data( Args&&... args )
760 return cxx_data_allocator().MoveNew( std::forward<Args>(args)... );
763 static void free_data( value_type* pData )
765 cxx_data_allocator().Delete( pData );
768 typedef std::unique_ptr< value_type, data_disposer > scoped_data_ptr;
770 using base_class::head;
775 bool insert_node( value_type* pData )
777 return insert_node_at( head(), pData );
780 bool insert_node_at( head_type* pHead, value_type* pData )
783 scoped_data_ptr p( pData );
784 if ( base_class::insert_at( pHead, *pData )) {
792 template <typename Q>
793 bool insert_at( head_type* pHead, Q&& val )
795 return insert_node_at( pHead, alloc_data( std::forward<Q>( val )));
798 template <typename Q, typename Func>
799 bool insert_at( head_type* pHead, Q&& key, Func f )
801 scoped_data_ptr pNode( alloc_data( std::forward<Q>( key )));
803 if ( base_class::insert_at( pHead, *pNode, f )) {
810 template <typename... Args>
811 bool emplace_at( head_type* pHead, Args&&... args )
813 return insert_node_at( pHead, alloc_data( std::forward<Args>(args)... ));
816 template <typename Q, typename Func>
817 std::pair<bool, bool> update_at( head_type* pHead, Q&& key, Func f, bool bAllowInsert )
819 scoped_data_ptr pData( alloc_data( std::forward<Q>( key )));
821 std::pair<bool, bool> ret = base_class::update_at( pHead, *pData, f, bAllowInsert );
828 template <typename Q, typename Compare, typename Func>
829 bool erase_at( head_type* pHead, Q const& key, Compare cmp, Func f )
831 return base_class::erase_at( pHead, key, cmp, f );
834 template <typename Q, typename Compare>
835 guarded_ptr extract_at( head_type* pHead, Q const& key, Compare cmp )
837 return base_class::extract_at( pHead, key, cmp );
840 template <typename Q, typename Compare>
841 bool find_at( head_type const* pHead, Q const& key, Compare cmp ) const
843 return base_class::find_at( pHead, key, cmp );
846 template <typename Q, typename Compare, typename Func>
847 bool find_at( head_type const* pHead, Q& val, Compare cmp, Func f ) const
849 return base_class::find_at( pHead, val, cmp, f );
852 template <typename Q, typename Compare>
853 iterator find_iterator_at( head_type const* pHead, Q const& key, Compare cmp ) const
855 return iterator( base_class::find_iterator_at( pHead, key, cmp ));
858 template <typename Q, typename Compare>
859 guarded_ptr get_at( head_type const* pHead, Q const& key, Compare cmp ) const
861 return base_class::get_at( pHead, key, cmp );
866 }} // namespace cds::container
868 #endif // #ifndef CDSLIB_CONTAINER_IMPL_ITERABLE_LIST_H