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_MICHAEL_KVLIST_H
32 #define CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
39 /// Michael's ordered list for key-value pair
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_MichaelKVList_gc
43 This is key-value variation of non-intrusive MichaelList.
44 Like standard container, this implementation split a value stored into two part -
45 constant key and alterable value.
47 Usually, ordered single-linked list is used as a building block for the hash table implementation.
48 The complexity of searching is <tt>O(N)</tt> where \p N is the item count in the list, not in the
52 - \p GC - garbage collector used
53 - \p Key - key type of an item stored in the list. It should be copy-constructible
54 - \p Value - value type stored in a list
55 - \p Traits - type traits, default is \p michael_list::traits
57 It is possible to declare option-based list with \p cds::container::michael_list::make_traits metafunction istead of \p Traits template
58 argument. For example, the following traits-based declaration of \p gc::HP Michael's list
60 #include <cds/container/michael_kvlist_hp.h>
61 // Declare comparator for the item
63 int operator ()( int i1, int i2 )
70 struct my_traits: public cds::container::michael_list::traits
72 typedef my_compare compare;
75 // Declare traits-based list
76 typedef cds::container::MichaelKVList< cds::gc::HP, int, int, my_traits > traits_based_list;
78 is equivalent for the following option-based list
80 #include <cds/container/michael_kvlist_hp.h>
82 // my_compare is the same
84 // Declare option-based list
85 typedef cds::container::MichaelKVList< cds::gc::HP, int, int,
86 typename cds::container::michael_list::make_traits<
87 cds::container::opt::compare< my_compare > // item comparator option
93 There are different specializations of this template for each garbage collecting schema used.
94 You should include appropriate .h-file depending on GC you are using:
95 - for gc::HP: \code #include <cds/container/michael_kvlist_hp.h> \endcode
96 - for gc::DHP: \code #include <cds/container/michael_kvlist_dhp.h> \endcode
97 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_kvlist_rcu.h> \endcode
98 - for gc::nogc: \code #include <cds/container/michael_kvlist_nogc.h> \endcode
104 #ifdef CDS_DOXYGEN_INVOKED
105 typename Traits = michael_list::traits
111 #ifdef CDS_DOXYGEN_INVOKED
112 protected intrusive::MichaelList< GC, implementation_defined, Traits >
114 protected details::make_michael_kvlist< GC, Key, Value, Traits >::type
118 typedef details::make_michael_kvlist< GC, Key, Value, Traits > maker;
119 typedef typename maker::type base_class;
123 #ifdef CDS_DOXYGEN_INVOKED
124 typedef Key key_type ; ///< Key type
125 typedef Value mapped_type ; ///< Type of value stored in the list
126 typedef std::pair<key_type const, mapped_type> value_type ; ///< key/value pair stored in the list
128 typedef typename maker::key_type key_type;
129 typedef typename maker::value_type mapped_type;
130 typedef typename maker::pair_type value_type;
133 typedef typename base_class::gc gc; ///< Garbage collector used
134 typedef typename base_class::back_off back_off; ///< Back-off strategy used
135 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
136 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
137 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
138 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
139 typedef typename base_class::stat stat; ///< Internal statistics
141 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
145 typedef typename base_class::value_type node_type;
146 typedef typename maker::cxx_allocator cxx_allocator;
147 typedef typename maker::node_deallocator node_deallocator;
148 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
150 typedef typename base_class::atomic_node_ptr head_type;
155 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_map<node_type, value_type> > guarded_ptr;
159 template <typename K>
160 static node_type * alloc_node(const K& key)
162 return cxx_allocator().New( key );
165 template <typename K, typename V>
166 static node_type * alloc_node( const K& key, const V& val )
168 return cxx_allocator().New( key, val );
171 template <typename K, typename... Args>
172 static node_type * alloc_node( K&& key, Args&&... args )
174 return cxx_allocator().MoveNew( std::forward<K>(key), std::forward<Args>(args)...);
177 static void free_node( node_type * pNode )
179 cxx_allocator().Delete( pNode );
182 struct node_disposer {
183 void operator()( node_type * pNode )
188 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
192 return base_class::m_pHead;
195 head_type const& head() const
197 return base_class::m_pHead;
203 template <bool IsConst>
204 class iterator_type: protected base_class::template iterator_type<IsConst>
206 typedef typename base_class::template iterator_type<IsConst> iterator_base;
208 iterator_type( head_type const& pNode )
209 : iterator_base( pNode )
212 friend class MichaelKVList;
215 typedef typename cds::details::make_const_type<mapped_type, IsConst>::reference value_ref;
216 typedef typename cds::details::make_const_type<mapped_type, IsConst>::pointer value_ptr;
218 typedef typename cds::details::make_const_type<value_type, IsConst>::reference pair_ref;
219 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer pair_ptr;
224 iterator_type( iterator_type const& src )
225 : iterator_base( src )
228 key_type const& key() const
230 typename iterator_base::value_ptr p = iterator_base::operator ->();
231 assert( p != nullptr );
232 return p->m_Data.first;
235 pair_ptr operator ->() const
237 typename iterator_base::value_ptr p = iterator_base::operator ->();
238 return p ? &(p->m_Data) : nullptr;
241 pair_ref operator *() const
243 typename iterator_base::value_ref p = iterator_base::operator *();
247 value_ref val() const
249 typename iterator_base::value_ptr p = iterator_base::operator ->();
250 assert( p != nullptr );
251 return p->m_Data.second;
255 iterator_type& operator ++()
257 iterator_base::operator ++();
262 bool operator ==(iterator_type<C> const& i ) const
264 return iterator_base::operator ==(i);
267 bool operator !=(iterator_type<C> const& i ) const
269 return iterator_base::operator !=(i);
277 The forward iterator for Michael's list has some features:
278 - it has no post-increment operator
279 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
280 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
281 may be thrown if a limit of guard count per thread is exceeded.
282 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
283 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
284 deleting operations it is no guarantee that you iterate all item in the list.
286 @warning Use this iterator on the concurrent container for debugging purpose only.
288 The iterator interface to access item data:
289 - <tt> operator -> </tt> - returns a pointer to \ref value_type for iterator
290 - <tt> operator *</tt> - returns a reference (a const reference for \p const_iterator) to \ref value_type for iterator
291 - <tt> const key_type& key() </tt> - returns a key reference for iterator
292 - <tt> mapped_type& val() </tt> - retuns a value reference for iterator (const reference for \p const_iterator)
294 For both functions the iterator should not be equal to <tt> end() </tt>
296 typedef iterator_type<false> iterator;
298 /// Const forward iterator
300 For iterator's features and requirements see \ref iterator
302 typedef iterator_type<true> const_iterator;
304 ///@name Forward iterators (only for debugging purpose)
306 /// Returns a forward iterator addressing the first element in a list
308 For empty list \code begin() == end() \endcode
312 return iterator( head() );
315 /// Returns an iterator that addresses the location succeeding the last element in a list
317 Do not use the value returned by <tt>end</tt> function to access any item.
318 Internally, <tt>end</tt> returning value equals to \p nullptr.
320 The returned value can be used only to control reaching the end of the list.
321 For empty list \code begin() == end() \endcode
328 /// Returns a forward const iterator addressing the first element in a list
329 const_iterator begin() const
331 return const_iterator( head() );
334 /// Returns a forward const iterator addressing the first element in a list
335 const_iterator cbegin() const
337 return const_iterator( head() );
340 /// Returns an const iterator that addresses the location succeeding the last element in a list
341 const_iterator end() const
343 return const_iterator();
346 /// Returns an const iterator that addresses the location succeeding the last element in a list
347 const_iterator cend() const
349 return const_iterator();
354 /// Default constructor
356 Initializes empty list
362 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
363 explicit MichaelKVList( Stat& st )
377 /// Inserts new node with key and default value
379 The function creates a node with \p key and default value, and then inserts the node created into the list.
382 - The \p key_type should be constructible from value of type \p K.
383 In trivial case, \p K is equal to \p key_type.
384 - The \p mapped_type should be default-constructible.
386 Returns \p true if inserting successful, \p false otherwise.
388 template <typename K>
389 bool insert( const K& key )
391 return insert_at( head(), key );
394 /// Inserts new node with a key and a value
396 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
399 - The \p key_type should be constructible from \p key of type \p K.
400 - The \p mapped_type should be constructible from \p val of type \p V.
402 Returns \p true if inserting successful, \p false otherwise.
404 template <typename K, typename V>
405 bool insert( const K& key, const V& val )
407 // We cannot use insert with functor here
408 // because we cannot lock inserted node for updating
409 // Therefore, we use separate function
410 return insert_at( head(), key, val );
413 /// Inserts new node and initialize it by a functor
415 This function inserts new node with key \p key and if inserting is successful then it calls
416 \p func functor with signature
419 void operator()( value_type& item );
423 The argument \p item of user-defined functor \p func is the reference
424 to the item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
425 User-defined functor \p func should guarantee that during changing item's value no any other changes
426 could be made on this list's item by concurrent threads.
427 The user-defined functor is called only if inserting is successful.
429 The \p key_type should be constructible from value of type \p K.
431 The function allows to split creating of new item into two part:
432 - create a new item from \p key;
433 - insert the new item into the list;
434 - if inserting is successful, initialize the value of item by calling \p func functor
436 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
437 it is preferable that the initialization should be completed only if inserting is successful.
439 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
441 template <typename K, typename Func>
442 bool insert_with( const K& key, Func func )
444 return insert_with_at( head(), key, func );
447 /// Updates data by \p key
449 The operation performs inserting or replacing the element with lock-free manner.
451 If the \p key not found in the list, then the new item created from \p key
452 will be inserted iff \p bAllowInsert is \p true.
453 (note that in this case the \ref key_type should be constructible from type \p K).
454 Otherwise, if \p key is found, the functor \p func is called with item found.
456 The functor \p Func signature is:
459 void operator()( bool bNew, value_type& item );
463 - \p bNew - \p true if the item has been inserted, \p false otherwise
464 - \p item - the item found or inserted
466 The functor may change any fields of the \p item.second of \p mapped_type;
467 however, \p func must guarantee that during changing no any other modifications
468 could be made on this item by concurrent threads.
470 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
471 \p second is true if new item has been added or \p false if the item with \p key
474 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
476 template <typename K, typename Func>
477 std::pair<bool, bool> update( K const& key, Func f, bool bAllowInsert = true )
479 return update_at( head(), key, f, bAllowInsert );
482 template <typename K, typename Func>
483 CDS_DEPRECATED("ensure() is deprecated, use update()")
484 std::pair<bool, bool> ensure( K const& key, Func f )
486 return update( key, f, true );
490 /// Inserts a new node using move semantics
492 \p key_type field of new item is constructed from \p key argument,
493 \p mapped_type field is done from \p args.
495 Returns \p true if inserting successful, \p false otherwise.
497 template <typename K, typename... Args>
498 bool emplace( K&& key, Args&&... args )
500 return emplace_at( head(), std::forward<K>(key), std::forward<Args>(args)... );
503 /// Deletes \p key from the list
504 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_val
506 Returns \p true if \p key is found and has been deleted, \p false otherwise
508 template <typename K>
509 bool erase( K const& key )
511 return erase_at( head(), key, intrusive_key_comparator() );
514 /// Deletes the item from the list using \p pred predicate for searching
516 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_val "erase(K const&)"
517 but \p pred is used for key comparing.
518 \p Less functor has the interface like \p std::less.
519 \p pred must imply the same element order as the comparator used for building the list.
521 template <typename K, typename Less>
522 bool erase_with( K const& key, Less pred )
525 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type() );
528 /// Deletes \p key from the list
529 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_func
530 The function searches an item with key \p key, calls \p f functor
531 and deletes the item. If \p key is not found, the functor is not called.
533 The functor \p Func interface:
536 void operator()(value_type& val) { ... }
540 Return \p true if key is found and deleted, \p false otherwise
544 template <typename K, typename Func>
545 bool erase( K const& key, Func f )
547 return erase_at( head(), key, intrusive_key_comparator(), f );
550 /// Deletes the item from the list using \p pred predicate for searching
552 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_func "erase(K const&, Func)"
553 but \p pred is used for key comparing.
554 \p Less functor has the interface like \p std::less.
555 \p pred must imply the same element order as the comparator used for building the list.
557 template <typename K, typename Less, typename Func>
558 bool erase_with( K const& key, Less pred, Func f )
561 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
564 /// Extracts the item from the list with specified \p key
565 /** \anchor cds_nonintrusive_MichaelKVList_hp_extract
566 The function searches an item with key equal to \p key,
567 unlinks it from the list, and returns it as \p guarded_ptr.
568 If \p key is not found the function returns an empty guarded pointer.
570 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
572 The \p disposer specified in \p Traits class template parameter is called automatically
573 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
574 will be destroyed or released.
575 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
579 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
583 ord_list::guarded_ptr gp(theList.extract( 5 ));
588 // Destructor of gp releases internal HP guard
592 template <typename K>
593 guarded_ptr extract( K const& key )
596 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
600 /// Extracts the item from the list with comparing functor \p pred
602 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_extract "extract(K const&)"
603 but \p pred predicate is used for key comparing.
605 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
607 \p pred must imply the same element order as the comparator used for building the list.
609 template <typename K, typename Less>
610 guarded_ptr extract_with( K const& key, Less pred )
614 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
618 /// Checks whether the list contains \p key
620 The function searches the item with key equal to \p key
621 and returns \p true if it is found, and \p false otherwise.
623 template <typename Q>
624 bool contains( Q const& key )
626 return find_at( head(), key, intrusive_key_comparator() );
629 template <typename Q>
630 CDS_DEPRECATED("deprecated, use contains()")
631 bool find( Q const& key )
633 return contains( key );
637 /// Checks whether the map contains \p key using \p pred predicate for searching
639 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
640 \p Less functor has the interface like \p std::less.
641 \p Less must imply the same element order as the comparator used for building the list.
643 template <typename Q, typename Less>
644 bool contains( Q const& key, Less pred )
647 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
650 template <typename Q, typename Less>
651 CDS_DEPRECATED("deprecated, use contains()")
652 bool find_with( Q const& key, Less pred )
655 return contains( key, pred );
659 /// Finds the key \p key and performs an action with it
660 /** \anchor cds_nonintrusive_MichaelKVList_hp_find_func
661 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
662 The interface of \p Func functor is:
665 void operator()( value_type& item );
668 where \p item is the item found.
670 The functor may change <tt>item.second</tt> that is reference to value of node.
671 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
672 The function does not serialize simultaneous access to the list \p item. If such access is
673 possible you must provide your own synchronization schema to exclude unsafe item modifications.
675 The function returns \p true if \p key is found, \p false otherwise.
677 template <typename Q, typename Func>
678 bool find( Q const& key, Func f )
680 return find_at( head(), key, intrusive_key_comparator(), f );
683 /// Finds the key \p val using \p pred predicate for searching
685 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_find_func "find(Q&, Func)"
686 but \p pred is used for key comparing.
687 \p Less functor has the interface like \p std::less.
688 \p pred must imply the same element order as the comparator used for building the list.
690 template <typename Q, typename Less, typename Func>
691 bool find_with( Q const& key, Less pred, Func f )
694 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
697 /// Finds the \p key and return the item found
698 /** \anchor cds_nonintrusive_MichaelKVList_hp_get
699 The function searches the item with key equal to \p key
700 and returns it as \p guarded_ptr.
701 If \p key is not found the function returns an empty guarded pointer.
703 The \p disposer specified in \p Traits class template parameter is called
704 by garbage collector \p GC automatically when returned \p guarded_ptr object
705 will be destroyed or released.
706 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
710 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
714 ord_list::guarded_ptr gp(theList.get( 5 ));
719 // Destructor of guarded_ptr releases internal HP guard
723 Note the compare functor specified for class \p Traits template parameter
724 should accept a parameter of type \p K that can be not the same as \p key_type.
726 template <typename K>
727 guarded_ptr get( K const& key )
730 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
734 /// Finds the \p key and return the item found
736 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_get "get( guarded_ptr& ptr, K const&)"
737 but \p pred is used for comparing the keys.
739 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
741 \p pred must imply the same element order as the comparator used for building the list.
743 template <typename K, typename Less>
744 guarded_ptr get_with( K const& key, Less pred )
748 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
752 /// Checks if the list is empty
755 return base_class::empty();
758 /// Returns list's item count
760 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
761 this function always returns 0.
763 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
764 is empty. To check list emptyness use \p empty() method.
768 return base_class::size();
777 /// Returns const reference to internal statistics
778 stat const& statistics() const
780 return base_class::statistics();
785 bool insert_node_at( head_type& refHead, node_type * pNode )
787 assert( pNode != nullptr );
788 scoped_node_ptr p( pNode );
789 if ( base_class::insert_at( refHead, *pNode )) {
796 template <typename K>
797 bool insert_at( head_type& refHead, const K& key )
799 return insert_node_at( refHead, alloc_node( key ));
802 template <typename K, typename V>
803 bool insert_at( head_type& refHead, const K& key, const V& val )
805 return insert_node_at( refHead, alloc_node( key, val ));
808 template <typename K, typename Func>
809 bool insert_with_at( head_type& refHead, const K& key, Func f )
811 scoped_node_ptr pNode( alloc_node( key ));
813 if ( base_class::insert_at( refHead, *pNode, [&f](node_type& node){ f( node.m_Data ); })) {
820 template <typename K, typename... Args>
821 bool emplace_at( head_type& refHead, K&& key, Args&&... args )
823 return insert_node_at( refHead, alloc_node( std::forward<K>(key), std::forward<Args>(args)... ));
826 template <typename K, typename Func>
827 std::pair<bool, bool> update_at( head_type& refHead, const K& key, Func f, bool bAllowInsert )
829 scoped_node_ptr pNode( alloc_node( key ));
831 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
832 [&f]( bool bNew, node_type& node, node_type& ){ f( bNew, node.m_Data ); },
834 if ( ret.first && ret.second )
840 template <typename K, typename Compare>
841 bool erase_at( head_type& refHead, K const& key, Compare cmp )
843 return base_class::erase_at( refHead, key, cmp );
846 template <typename K, typename Compare, typename Func>
847 bool erase_at( head_type& refHead, K const& key, Compare cmp, Func f )
849 return base_class::erase_at( refHead, key, cmp, [&f]( node_type const & node ){ f( const_cast<value_type&>(node.m_Data)); });
851 template <typename K, typename Compare>
852 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
854 return base_class::extract_at( refHead, guard, key, cmp );
857 template <typename K, typename Compare>
858 bool find_at( head_type& refHead, K const& key, Compare cmp )
860 return base_class::find_at( refHead, key, cmp );
863 template <typename K, typename Compare, typename Func>
864 bool find_at( head_type& refHead, K& key, Compare cmp, Func f )
866 return base_class::find_at( refHead, key, cmp, [&f](node_type& node, K const&){ f( node.m_Data ); });
869 template <typename K, typename Compare>
870 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
872 return base_class::get_at( refHead, guard, key, cmp );
878 }} // namespace cds::container
880 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H