2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
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::atomic_node_ptr 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( head_type const& pNode )
178 : iterator_base( pNode )
181 iterator_type( iterator_base it )
182 : iterator_base( it )
186 typedef typename iterator_base::value_ptr value_ptr;
187 typedef typename iterator_base::value_ref value_ref;
192 iterator_type( iterator_type const& src )
193 : iterator_base( src )
196 value_ptr operator ->() const
198 return iterator_base::operator ->();
201 value_ref operator *() const
203 return iterator_base::operator *();
207 iterator_type& operator ++()
209 iterator_base::operator ++();
214 bool operator ==(iterator_type<C> const& i ) const
216 return iterator_base::operator ==(i);
219 bool operator !=(iterator_type<C> const& i ) const
221 return iterator_base::operator !=(i);
227 ///@name Thread-safe forward iterators
231 The forward iterator for iterable list has some features:
232 - it has no post-increment operator
233 - to protect the value, the iterator contains a GC-specific guard.
234 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
235 may be thrown if the limit of guard count per thread is exceeded.
236 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
237 - Iterator is thread-safe: even if an element the iterator points to is removed, the iterator stays valid because
238 it contains the guard keeping the value from to be recycled.
240 The iterator interface:
244 // Default constructor
248 iterator( iterator const& src );
250 // Dereference operator
251 value_type * operator ->() const;
253 // Dereference operator
254 value_type& operator *() const;
256 // Preincrement operator
257 iterator& operator ++();
259 // Assignment operator
260 iterator& operator = (iterator const& src);
262 // Equality operators
263 bool operator ==(iterator const& i ) const;
264 bool operator !=(iterator const& i ) const;
268 @note For two iterators pointed to the same element the value can be different;
272 assert( &(*it1) == &(*it2) );
274 can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread.
275 The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing.
276 Other iterator can observe modified value of the element.
278 typedef iterator_type<false> iterator;
280 /// Const forward iterator
282 For iterator's features and requirements see \ref iterator
284 typedef iterator_type<true> const_iterator;
286 /// Returns a forward iterator addressing the first element in a list
288 For empty list \code begin() == end() \endcode
292 return iterator( head() );
295 /// Returns an iterator that addresses the location succeeding the last element in a list
297 Do not use the value returned by <tt>end</tt> function to access any item.
298 Internally, <tt>end</tt> returning value equals to \p nullptr.
300 The returned value can be used only to control reaching the end of the list.
301 For empty list \code begin() == end() \endcode
308 /// Returns a forward const iterator addressing the first element in a list
309 const_iterator begin() const
311 return const_iterator( head() );
314 /// Returns a forward const iterator addressing the first element in a list
315 const_iterator cbegin() const
317 return const_iterator( head() );
320 /// Returns an const iterator that addresses the location succeeding the last element in a list
321 const_iterator end() const
323 return const_iterator();
326 /// Returns an const iterator that addresses the location succeeding the last element in a list
327 const_iterator cend() const
329 return const_iterator();
334 /// Default constructor
336 Initialize empty list
342 template <typename Stat, typename = std::enable_if<std::is_same<stat, iterable_list::wrapped_stat<Stat>>::value >>
343 explicit IterableList( Stat& st )
357 The function creates a node with copy of \p val value
358 and then inserts the node created into the list.
360 The type \p Q should contain least the complete key of the node.
361 The object of \ref value_type should be constructible from \p val of type \p Q.
362 In trivial case, \p Q is equal to \ref value_type.
364 Returns \p true if inserting successful, \p false otherwise.
366 template <typename Q>
367 bool insert( Q&& val )
369 return insert_at( head(), std::forward<Q>( val ));
374 This function inserts new node with default-constructed value and then it calls
375 \p func functor with signature
377 void func( value_type& data );
380 The argument \p data of user-defined functor \p func is the reference
381 to the list's item inserted. User-defined functor \p func should guarantee that during changing
382 item's value no any other changes could be made on this list's item by concurrent threads.
383 The user-defined functor is called only if inserting is success.
385 The type \p Q should contain the complete key of the node.
386 The object of \p value_type should be constructible from \p key of type \p Q.
388 The function allows to split creating of new item into two part:
389 - create item from \p key with initializing key-fields only;
390 - insert new item into the list;
391 - if inserting is successful, initialize non-key fields of item by calling \p func functor
393 The method can be useful if complete initialization of object of \p value_type is heavyweight and
394 it is preferable that the initialization should be completed only if inserting is successful.
396 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
398 template <typename Q, typename Func>
399 bool insert( Q&& key, Func func )
401 return insert_at( head(), std::forward<Q>( key ), func );
404 /// Updates data by \p key
406 The operation performs inserting or replacing the element with lock-free manner.
408 If the \p key not found in the list, then the new item created from \p key
409 will be inserted iff \p bAllowInsert is \p true.
410 Otherwise, if \p key is found, the functor \p func is called with item found.
412 The functor \p func is called after inserting or replacing, it signature is:
414 void func( value_type& val, value_type * old );
417 - \p val - a new data constructed from \p key
418 - \p old - old value that will be retired. If new item has been inserted then \p old is \p nullptr.
420 The functor may change non-key fields of \p val; however, \p func must guarantee
421 that during changing no any other modifications could be made on this item by concurrent threads.
423 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
424 \p second is true if new item has been added or \p false if the item with such \p key
427 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
429 template <typename Q, typename Func>
430 std::pair<bool, bool> update( Q&& key, Func func, bool bAllowInsert = true )
432 return update_at( head(), std::forward<Q>( key ), func, bAllowInsert );
437 The operation performs inserting or updating data with lock-free manner.
439 If the item \p key is not found in the list, then \p key is inserted
440 iff \p bInsert is \p true.
441 Otherwise, the current element is changed to \p key, the old element will be retired later.
443 \p value_type should be constructible from \p key.
445 Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
446 \p second is \p true if \p key has been added or \p false if the item with that key
449 template <typename Q>
450 std::pair<bool, bool> upsert( Q&& key, bool bInsert = true )
452 return update_at( head(), std::forward<Q>( key ), []( value_type&, value_type* ) {}, bInsert );
455 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
457 Returns \p true if inserting successful, \p false otherwise.
459 template <typename... Args>
460 bool emplace( Args&&... args )
462 return emplace_at( head(), std::forward<Args>(args)... );
465 /// Delete \p key from the list
467 Since the key of IterableList's item type \p value_type is not explicitly specified,
468 template parameter \p Q sould contain the complete key to search in the list.
469 The list item comparator should be able to compare the type \p value_type
472 Return \p true if key is found and deleted, \p false otherwise
474 template <typename Q>
475 bool erase( Q const& key )
477 return erase_at( head(), key, key_comparator(), [](value_type const&){} );
480 /// Deletes the item from the list using \p pred predicate for searching
482 The function is an analog of \p erase(Q const&) but \p pred is used for key comparing.
483 \p Less functor has the interface like \p std::less.
484 \p pred must imply the same element order as the comparator used for building the list.
486 template <typename Q, typename Less>
487 bool erase_with( Q const& key, Less pred )
490 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
493 /// Deletes \p key from the list
495 The function searches an item with key \p key, calls \p f functor with item found
496 and deletes it. If \p key is not found, the functor is not called.
498 The functor \p Func interface:
501 void operator()(const value_type& val) { ... }
505 Since the key of IterableList's item type \p value_type is not explicitly specified,
506 template parameter \p Q should contain the complete key to search in the list.
507 The list item comparator should be able to compare the type \p value_type of list item
510 Return \p true if key is found and deleted, \p false otherwise
512 template <typename Q, typename Func>
513 bool erase( Q const& key, Func f )
515 return erase_at( head(), key, key_comparator(), f );
518 /// Deletes the item from the list using \p pred predicate for searching
520 The function is an analog of \p erase(Q const&, Func) but \p pred is used for key comparing.
521 \p Less functor has the interface like \p std::less.
522 \p pred must imply the same element order as the comparator used for building the list.
524 template <typename Q, typename Less, typename Func>
525 bool erase_with( Q const& key, Less pred, Func f )
528 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
531 /// Extracts the item from the list with specified \p key
533 The function searches an item with key equal to \p key,
534 unlinks it from the list, and returns it as \p guarded_ptr.
535 If \p key is not found the function returns an empty guarded pointer.
537 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
539 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
543 typedef cds::container::IterableList< cds::gc::HP, foo, my_traits > ord_list;
547 ord_list::guarded_ptr gp(theList.extract( 5 ));
552 // Destructor of gp releases internal HP guard and frees the item
556 template <typename Q>
557 guarded_ptr extract( Q const& key )
559 return extract_at( head(), key, key_comparator() );
562 /// Extracts the item from the list with comparing functor \p pred
564 The function is an analog of \p extract(Q const&) but \p pred predicate is used for key comparing.
566 \p Less functor has the semantics like \p std::less but it should accept arguments
567 of type \p value_type and \p Q in any order.
568 \p pred must imply the same element order as the comparator used for building the list.
570 template <typename Q, typename Less>
571 guarded_ptr extract_with( Q const& key, Less pred )
574 return extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
577 /// Checks whether the list contains \p key
579 The function searches the item with key equal to \p key
580 and returns \p true if it is found, and \p false otherwise.
582 template <typename Q>
583 bool contains( Q const& key ) const
585 return find_at( head(), key, key_comparator() );
588 /// Checks whether the list contains \p key using \p pred predicate for searching
590 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
591 \p Less functor has the interface like \p std::less.
592 \p pred must imply the same element order as the comparator used for building the list.
594 template <typename Q, typename Less>
595 bool contains( Q const& key, Less pred ) const
598 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
601 /// Finds \p key and perform an action with it
603 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
604 The interface of \p Func functor is:
607 void operator()( value_type& item, Q& key );
610 where \p item is the item found, \p key is the <tt>find</tt> function argument.
612 The functor may change non-key fields of \p item. Note that the function is only guarantee
613 that \p item cannot be deleted during functor is executing.
614 The function does not serialize simultaneous access to the list \p item. If such access is
615 possible you must provide your own synchronization schema to exclude unsafe item modifications.
617 The function returns \p true if \p key is found, \p false otherwise.
619 template <typename Q, typename Func>
620 bool find( Q& key, Func f ) const
622 return find_at( head(), key, key_comparator(), f );
625 template <typename Q, typename Func>
626 bool find( Q const& key, Func f ) const
628 return find_at( head(), key, key_comparator(), f );
632 /// Finds \p key in the list and returns iterator pointed to the item found
634 If \p key is not found the function returns \p end().
636 template <typename Q>
637 iterator find( Q const& key ) const
639 return find_iterator_at( head(), key, key_comparator());
642 /// Finds \p key using \p pred predicate for searching
644 The function is an analog of \p find(Q&, Func) but \p pred is used for key comparing.
645 \p Less functor has the interface like \p std::less.
646 \p pred must imply the same element order as the comparator used for building the list.
648 template <typename Q, typename Less, typename Func>
649 bool find_with( Q& key, Less pred, Func f ) const
652 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
655 template <typename Q, typename Less, typename Func>
656 bool find_with( Q const& key, Less pred, Func f ) const
659 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
663 /// Finds \p key in the list using \p pred predicate for searching and returns iterator pointed to the item found
665 The function is an analog of \p find(Q&) but \p pred is used for key comparing.
666 \p Less functor has the interface like \p std::less.
667 \p pred must imply the same element order as the comparator used for building the list.
669 If \p key is not found the function returns \p end().
671 template <typename Q, typename Less>
672 iterator find_with( Q const& key, Less pred ) const
675 return find_iterator_at( head(), key, cds::opt::details::make_comparator_from_less<Less>());
678 /// Finds \p key and return the item found
679 /** \anchor cds_nonintrusive_MichaelList_hp_get
680 The function searches the item with key equal to \p key
681 and returns it as \p guarded_ptr.
682 If \p key is not found the function returns an empty guarded pointer.
684 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
688 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
692 ord_list::guarded_ptr gp(theList.get( 5 ));
697 // Destructor of guarded_ptr releases internal HP guard and frees the item
701 Note the compare functor specified for class \p Traits template parameter
702 should accept a parameter of type \p Q that can be not the same as \p value_type.
704 template <typename Q>
705 guarded_ptr get( Q const& key ) const
707 return get_at( head(), key, key_comparator() );
710 /// Finds \p key and return the item found
712 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
713 but \p pred is used for comparing the keys.
715 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
717 \p pred must imply the same element order as the comparator used for building the list.
719 template <typename Q, typename Less>
720 guarded_ptr get_with( Q const& key, Less pred ) const
723 return get_at( head(), key, typename maker::template less_wrapper<Less>::type() );
726 /// Checks if the list is empty
728 Emptiness is checked by item counting: if item count is zero then the set is empty.
729 Thus, if you need to use \p %empty() you should provide appropriate (non-empty) \p iterable_list::traits::item_counter
734 return base_class::empty();
737 /// Returns list's item count
739 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
740 this function always returns 0.
744 return base_class::size();
747 /// Clears the list (thread safe, not atomic)
753 /// Returns const reference to internal statistics
754 stat const& statistics() const
756 return base_class::statistics();
761 template <typename... Args>
762 static value_type* alloc_data( Args&&... args )
764 return cxx_data_allocator().MoveNew( std::forward<Args>(args)... );
767 static void free_data( value_type* pData )
769 cxx_data_allocator().Delete( pData );
772 typedef std::unique_ptr< value_type, data_disposer > scoped_data_ptr;
776 return base_class::m_pHead;
779 head_type const& head() const
781 return base_class::m_pHead;
787 bool insert_node( value_type* pData )
789 return insert_node_at( head(), pData );
792 bool insert_node_at( head_type& refHead, value_type* pData )
795 scoped_data_ptr p( pData );
796 if ( base_class::insert_at( refHead, *pData )) {
804 template <typename Q>
805 bool insert_at( head_type& refHead, Q&& val )
807 return insert_node_at( refHead, alloc_data( std::forward<Q>( val )));
810 template <typename Q, typename Func>
811 bool insert_at( head_type& refHead, Q&& key, Func f )
813 scoped_data_ptr pNode( alloc_data( std::forward<Q>( key )));
815 if ( base_class::insert_at( refHead, *pNode, f )) {
822 template <typename... Args>
823 bool emplace_at( head_type& refHead, Args&&... args )
825 return insert_node_at( refHead, alloc_data( std::forward<Args>(args)... ));
828 template <typename Q, typename Func>
829 std::pair<bool, bool> update_at( head_type& refHead, Q&& key, Func f, bool bAllowInsert )
831 scoped_data_ptr pData( alloc_data( std::forward<Q>( key )));
833 std::pair<bool, bool> ret = base_class::update_at( refHead, *pData, f, bAllowInsert );
840 template <typename Q, typename Compare, typename Func>
841 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
843 return base_class::erase_at( refHead, key, cmp, f );
846 template <typename Q, typename Compare>
847 guarded_ptr extract_at( head_type& refHead, Q const& key, Compare cmp )
849 return base_class::extract_at( refHead, key, cmp );
852 template <typename Q, typename Compare>
853 bool find_at( head_type const& refHead, Q const& key, Compare cmp ) const
855 return base_class::find_at( refHead, key, cmp );
858 template <typename Q, typename Compare, typename Func>
859 bool find_at( head_type const& refHead, Q& val, Compare cmp, Func f ) const
861 return base_class::find_at( refHead, val, cmp, f );
864 template <typename Q, typename Compare>
865 iterator find_iterator_at( head_type const& refHead, Q const& key, Compare cmp ) const
867 return iterator( base_class::find_iterator_at( refHead, key, cmp ));
870 template <typename Q, typename Compare>
871 guarded_ptr get_at( head_type const& refHead, Q const& key, Compare cmp ) const
873 return base_class::get_at( refHead, key, cmp );
879 }} // namespace cds::container
881 #endif // #ifndef CDSLIB_CONTAINER_IMPL_ITERABLE_LIST_H