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
144 typedef typename maker::cxx_data_allocator cxx_data_allocator;
145 typedef typename maker::data_disposer data_disposer;
146 typedef typename base_class::atomic_node_ptr head_type;
151 typedef typename base_class::guarded_ptr guarded_ptr;
155 template <bool IsConst>
156 class iterator_type: protected base_class::template iterator_type<IsConst>
158 typedef typename base_class::template iterator_type<IsConst> iterator_base;
159 friend class IterableList;
161 iterator_type( head_type const& pNode )
162 : iterator_base( pNode )
165 iterator_type( iterator_base it )
166 : iterator_base( it )
170 typedef typename iterator_base::value_ptr value_ptr;
171 typedef typename iterator_base::value_ref value_ref;
176 iterator_type( iterator_type const& src )
177 : iterator_base( src )
180 value_ptr operator ->() const
182 return iterator_base::operator ->();
185 value_ref operator *() const
187 return iterator_base::operator *();
191 iterator_type& operator ++()
193 iterator_base::operator ++();
198 bool operator ==(iterator_type<C> const& i ) const
200 return iterator_base::operator ==(i);
203 bool operator !=(iterator_type<C> const& i ) const
205 return iterator_base::operator !=(i);
211 ///@name Thread-safe forward iterators
215 The forward iterator for iterable list has some features:
216 - it has no post-increment operator
217 - to protect the value, the iterator contains a GC-specific guard.
218 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
219 may be thrown if the limit of guard count per thread is exceeded.
220 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
221 - Iterator is thread-safe: even if an element the iterator points to is removed, the iterator stays valid because
222 it contains the guard keeping the value from to be recycled.
224 The iterator interface:
228 // Default constructor
232 iterator( iterator const& src );
234 // Dereference operator
235 value_type * operator ->() const;
237 // Dereference operator
238 value_type& operator *() const;
240 // Preincrement operator
241 iterator& operator ++();
243 // Assignment operator
244 iterator& operator = (iterator const& src);
246 // Equality operators
247 bool operator ==(iterator const& i ) const;
248 bool operator !=(iterator const& i ) const;
252 @note For two iterators pointed to the same element the value can be different;
256 assert( &(*it1) == &(*it2) );
258 can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread.
259 The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing.
260 Other iterator can observe modified value of the element.
262 typedef iterator_type<false> iterator;
264 /// Const forward iterator
266 For iterator's features and requirements see \ref iterator
268 typedef iterator_type<true> const_iterator;
270 /// Returns a forward iterator addressing the first element in a list
272 For empty list \code begin() == end() \endcode
276 return iterator( head() );
279 /// Returns an iterator that addresses the location succeeding the last element in a list
281 Do not use the value returned by <tt>end</tt> function to access any item.
282 Internally, <tt>end</tt> returning value equals to \p nullptr.
284 The returned value can be used only to control reaching the end of the list.
285 For empty list \code begin() == end() \endcode
292 /// Returns a forward const iterator addressing the first element in a list
293 const_iterator begin() const
295 return const_iterator( head() );
298 /// Returns a forward const iterator addressing the first element in a list
299 const_iterator cbegin() const
301 return const_iterator( head() );
304 /// Returns an const iterator that addresses the location succeeding the last element in a list
305 const_iterator end() const
307 return const_iterator();
310 /// Returns an const iterator that addresses the location succeeding the last element in a list
311 const_iterator cend() const
313 return const_iterator();
318 /// Default constructor
320 Initialize empty list
326 template <typename Stat, typename = std::enable_if<std::is_same<stat, iterable_list::wrapped_stat<Stat>>::value >>
327 explicit IterableList( Stat& st )
341 The function creates a node with copy of \p val value
342 and then inserts the node created into the list.
344 The type \p Q should contain least the complete key of the node.
345 The object of \ref value_type should be constructible from \p val of type \p Q.
346 In trivial case, \p Q is equal to \ref value_type.
348 Returns \p true if inserting successful, \p false otherwise.
350 template <typename Q>
351 bool insert( Q const& val )
353 return insert_at( head(), val );
358 This function inserts new node with default-constructed value and then it calls
359 \p func functor with signature
361 void func( value_type& data );
364 The argument \p data of user-defined functor \p func is the reference
365 to the list's item inserted. User-defined functor \p func should guarantee that during changing
366 item's value no any other changes could be made on this list's item by concurrent threads.
367 The user-defined functor is called only if inserting is success.
369 The type \p Q should contain the complete key of the node.
370 The object of \p value_type should be constructible from \p key of type \p Q.
372 The function allows to split creating of new item into two part:
373 - create item from \p key with initializing key-fields only;
374 - insert new item into the list;
375 - if inserting is successful, initialize non-key fields of item by calling \p func functor
377 The method can be useful if complete initialization of object of \p value_type is heavyweight and
378 it is preferable that the initialization should be completed only if inserting is successful.
380 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
382 template <typename Q, typename Func>
383 bool insert( Q const& key, Func func )
385 return insert_at( head(), key, func );
388 /// Updates data by \p key
390 The operation performs inserting or replacing the element with lock-free manner.
392 If the \p key not found in the list, then the new item created from \p key
393 will be inserted iff \p bAllowInsert is \p true.
394 Otherwise, if \p key is found, the functor \p func is called with item found.
396 The functor \p func is called after inserting or replacing, it signature is:
398 void func( value_type& val, value_type * old );
401 - \p val - a new data constructed from \p key
402 - \p old - old value that will be retired. If new item has been inserted then \p old is \p nullptr.
404 The functor may change non-key fields of \p val; however, \p func must guarantee
405 that during changing no any other modifications could be made on this item by concurrent threads.
407 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
408 \p second is true if new item has been added or \p false if the item with such \p key
411 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
413 template <typename Q, typename Func>
414 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
416 return update_at( head(), key, func, bAllowInsert );
421 The operation performs inserting or updating data with lock-free manner.
423 If the item \p key is not found in the list, then \p key is inserted
424 iff \p bInsert is \p true.
425 Otherwise, the current element is changed to \p key, the old element will be retired later.
427 \p value_type should be constructible from \p key.
429 Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
430 \p second is \p true if \p key has been added or \p false if the item with that key
433 template <typename Q>
434 std::pair<bool, bool> upsert( Q&& key, bool bInsert = true )
436 return update_at( head(), std::forward<Q>( key ), []( value_type&, value_type* ) {}, bInsert );
439 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
441 Returns \p true if inserting successful, \p false otherwise.
443 template <typename... Args>
444 bool emplace( Args&&... args )
446 return emplace_at( head(), std::forward<Args>(args)... );
449 /// Delete \p key from the list
451 Since the key of IterableList's item type \p value_type is not explicitly specified,
452 template parameter \p Q sould contain the complete key to search in the list.
453 The list item comparator should be able to compare the type \p value_type
456 Return \p true if key is found and deleted, \p false otherwise
458 template <typename Q>
459 bool erase( Q const& key )
461 return erase_at( head(), key, key_comparator(), [](value_type const&){} );
464 /// Deletes the item from the list using \p pred predicate for searching
466 The function is an analog of \p erase(Q const&) but \p pred is used for key comparing.
467 \p Less functor has the interface like \p std::less.
468 \p pred must imply the same element order as the comparator used for building the list.
470 template <typename Q, typename Less>
471 bool erase_with( Q const& key, Less pred )
474 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
477 /// Deletes \p key from the list
479 The function searches an item with key \p key, calls \p f functor with item found
480 and deletes it. If \p key is not found, the functor is not called.
482 The functor \p Func interface:
485 void operator()(const value_type& val) { ... }
489 Since the key of IterableList's item type \p value_type is not explicitly specified,
490 template parameter \p Q should contain the complete key to search in the list.
491 The list item comparator should be able to compare the type \p value_type of list item
494 Return \p true if key is found and deleted, \p false otherwise
496 template <typename Q, typename Func>
497 bool erase( Q const& key, Func f )
499 return erase_at( head(), key, key_comparator(), f );
502 /// Deletes the item from the list using \p pred predicate for searching
504 The function is an analog of \p erase(Q const&, Func) but \p pred is used for key comparing.
505 \p Less functor has the interface like \p std::less.
506 \p pred must imply the same element order as the comparator used for building the list.
508 template <typename Q, typename Less, typename Func>
509 bool erase_with( Q const& key, Less pred, Func f )
512 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
515 /// Extracts the item from the list with specified \p key
517 The function searches an item with key equal to \p key,
518 unlinks it from the list, and returns it as \p guarded_ptr.
519 If \p key is not found the function returns an empty guarded pointer.
521 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
523 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
527 typedef cds::container::IterableList< cds::gc::HP, foo, my_traits > ord_list;
531 ord_list::guarded_ptr gp(theList.extract( 5 ));
536 // Destructor of gp releases internal HP guard and frees the item
540 template <typename Q>
541 guarded_ptr extract( Q const& key )
544 extract_at( head(), gp.guard(), key, key_comparator() );
548 /// Extracts the item from the list with comparing functor \p pred
550 The function is an analog of \p extract(Q const&) but \p pred predicate is used for key comparing.
552 \p Less functor has the semantics like \p std::less but it should accept arguments
553 of type \p value_type and \p Q in any order.
554 \p pred must imply the same element order as the comparator used for building the list.
556 template <typename Q, typename Less>
557 guarded_ptr extract_with( Q const& key, Less pred )
561 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
565 /// Checks whether the list contains \p key
567 The function searches the item with key equal to \p key
568 and returns \p true if it is found, and \p false otherwise.
570 template <typename Q>
571 bool contains( Q const& key ) const
573 return find_at( head(), key, key_comparator() );
576 /// Checks whether the list contains \p key using \p pred predicate for searching
578 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
579 \p Less functor has the interface like \p std::less.
580 \p pred must imply the same element order as the comparator used for building the list.
582 template <typename Q, typename Less>
583 bool contains( Q const& key, Less pred ) const
586 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
589 /// Finds \p key and perform an action with it
591 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
592 The interface of \p Func functor is:
595 void operator()( value_type& item, Q& key );
598 where \p item is the item found, \p key is the <tt>find</tt> function argument.
600 The functor may change non-key fields of \p item. Note that the function is only guarantee
601 that \p item cannot be deleted during functor is executing.
602 The function does not serialize simultaneous access to the list \p item. If such access is
603 possible you must provide your own synchronization schema to exclude unsafe item modifications.
605 The function returns \p true if \p key is found, \p false otherwise.
607 template <typename Q, typename Func>
608 bool find( Q& key, Func f ) const
610 return find_at( head(), key, key_comparator(), f );
613 template <typename Q, typename Func>
614 bool find( Q const& key, Func f ) const
616 return find_at( head(), key, key_comparator(), f );
620 /// Finds \p key in the list and returns iterator pointed to the item found
622 If \p key is not found the function returns \p end().
624 template <typename Q>
625 iterator find( Q& key ) const
627 return find_iterator_at( head(), key, key_comparator());
630 template <typename Q>
631 iterator find( Q const& key ) const
633 return find_iterator_at( head(), key, key_comparator() );
637 /// Finds \p key using \p pred predicate for searching
639 The function is an analog of \p find(Q&, Func) but \p pred is used for key comparing.
640 \p Less functor has the interface like \p std::less.
641 \p pred must imply the same element order as the comparator used for building the list.
643 template <typename Q, typename Less, typename Func>
644 bool find_with( Q& key, Less pred, Func f ) const
647 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
650 template <typename Q, typename Less, typename Func>
651 bool find_with( Q const& key, Less pred, Func f ) const
654 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
658 /// Finds \p key in the list using \p pred predicate for searching and returns iterator pointed to the item found
660 The function is an analog of \p find(Q&) but \p pred is used for key comparing.
661 \p Less functor has the interface like \p std::less.
662 \p pred must imply the same element order as the comparator used for building the list.
664 If \p key is not found the function returns \p end().
666 template <typename Q, typename Less>
667 iterator find_with( Q& key, Less pred ) const
670 return find_iterator_at( head(), key, cds::opt::details::make_comparator_from_less<Less>());
673 template <typename Q, typename Less>
674 iterator find_with( Q const& key, Less pred ) const
677 return find_iterator_at( head(), key, cds::opt::details::make_comparator_from_less<Less>());
681 /// Finds \p key and return the item found
682 /** \anchor cds_nonintrusive_MichaelList_hp_get
683 The function searches the item with key equal to \p key
684 and returns it as \p guarded_ptr.
685 If \p key is not found the function returns an empty guarded pointer.
687 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
691 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
695 ord_list::guarded_ptr gp(theList.get( 5 ));
700 // Destructor of guarded_ptr releases internal HP guard and frees the item
704 Note the compare functor specified for class \p Traits template parameter
705 should accept a parameter of type \p Q that can be not the same as \p value_type.
707 template <typename Q>
708 guarded_ptr get( Q const& key ) const
711 get_at( head(), gp.guard(), key, key_comparator() );
715 /// Finds \p key and return the item found
717 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
718 but \p pred is used for comparing the keys.
720 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
722 \p pred must imply the same element order as the comparator used for building the list.
724 template <typename Q, typename Less>
725 guarded_ptr get_with( Q const& key, Less pred ) const
729 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
733 /// Checks if the list is empty
735 Emptiness is checked by item counting: if item count is zero then the set is empty.
736 Thus, if you need to use \p %empty() you should provide appropriate (non-empty) \p iterable_list::traits::item_counter
741 return base_class::empty();
744 /// Returns list's item count
746 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
747 this function always returns 0.
751 return base_class::size();
754 /// Clears the list (thread safe, not atomic)
760 /// Returns const reference to internal statistics
761 stat const& statistics() const
763 return base_class::statistics();
768 template <typename Q>
769 static value_type* alloc_data( Q const& v )
771 return cxx_data_allocator().New( v );
774 template <typename... Args>
775 static value_type* alloc_data( Args&&... args )
777 return cxx_data_allocator().MoveNew( std::forward<Args>(args)... );
780 static void free_data( value_type* pData )
782 cxx_data_allocator().Delete( pData );
785 typedef std::unique_ptr< value_type, data_disposer > scoped_data_ptr;
789 return base_class::m_pHead;
792 head_type const& head() const
794 return base_class::m_pHead;
800 bool insert_node( value_type * pData )
802 return insert_node_at( head(), pData );
805 bool insert_node_at( head_type& refHead, value_type* pData )
808 scoped_data_ptr p( pData );
809 if ( base_class::insert_at( refHead, *pData )) {
817 template <typename Q>
818 bool insert_at( head_type& refHead, Q const& val )
820 return insert_node_at( refHead, alloc_data( val ));
823 template <typename Q, typename Func>
824 bool insert_at( head_type& refHead, Q const& key, Func f )
826 scoped_data_ptr pNode( alloc_data( key ));
828 if ( base_class::insert_at( refHead, *pNode, f )) {
835 template <typename... Args>
836 bool emplace_at( head_type& refHead, Args&&... args )
838 return insert_node_at( refHead, alloc_data( std::forward<Args>(args) ... ));
841 template <typename Q, typename Func>
842 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
844 scoped_data_ptr pData( alloc_data( key ) );
846 std::pair<bool, bool> ret = base_class::update_at( refHead, *pData, f, bAllowInsert );
853 template <typename Q, typename Compare, typename Func>
854 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
856 return base_class::erase_at( refHead, key, cmp, f );
859 template <typename Q, typename Compare>
860 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
862 return base_class::extract_at( refHead, guard, key, cmp );
865 template <typename Q, typename Compare>
866 bool find_at( head_type const& refHead, Q const& key, Compare cmp ) const
868 return base_class::find_at( refHead, key, cmp );
871 template <typename Q, typename Compare, typename Func>
872 bool find_at( head_type const& refHead, Q& val, Compare cmp, Func f ) const
874 return base_class::find_at( refHead, val, cmp, f );
877 template <typename Q, typename Compare>
878 iterator find_iterator_at( head_type const& refHead, Q const& key, Compare cmp ) const
880 return iterator( base_class::find_iterator_at( refHead, key, cmp ));
883 template <typename Q, typename Compare>
884 bool get_at( head_type const& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp ) const
886 return base_class::get_at( refHead, guard, key, cmp );
892 }} // namespace cds::container
894 #endif // #ifndef CDSLIB_CONTAINER_IMPL_ITERABLE_LIST_H