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 fo 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
142 typedef typename base_class::value_type node_type;
143 typedef typename maker::cxx_allocator cxx_allocator;
144 typedef typename maker::node_deallocator node_deallocator;
145 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
147 typedef typename base_class::atomic_node_ptr head_type;
152 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_map<node_type, value_type> > guarded_ptr;
156 template <typename K>
157 static node_type * alloc_node(const K& key)
159 return cxx_allocator().New( key );
162 template <typename K, typename V>
163 static node_type * alloc_node( const K& key, const V& val )
165 return cxx_allocator().New( key, val );
168 template <typename K, typename... Args>
169 static node_type * alloc_node( K&& key, Args&&... args )
171 return cxx_allocator().MoveNew( std::forward<K>(key), std::forward<Args>(args)...);
174 static void free_node( node_type * pNode )
176 cxx_allocator().Delete( pNode );
179 struct node_disposer {
180 void operator()( node_type * pNode )
185 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
189 return base_class::m_pHead;
192 head_type const& head() const
194 return base_class::m_pHead;
200 template <bool IsConst>
201 class iterator_type: protected base_class::template iterator_type<IsConst>
203 typedef typename base_class::template iterator_type<IsConst> iterator_base;
205 iterator_type( head_type const& pNode )
206 : iterator_base( pNode )
209 friend class MichaelKVList;
212 typedef typename cds::details::make_const_type<mapped_type, IsConst>::reference value_ref;
213 typedef typename cds::details::make_const_type<mapped_type, IsConst>::pointer value_ptr;
215 typedef typename cds::details::make_const_type<value_type, IsConst>::reference pair_ref;
216 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer pair_ptr;
221 iterator_type( iterator_type const& src )
222 : iterator_base( src )
225 key_type const& key() const
227 typename iterator_base::value_ptr p = iterator_base::operator ->();
228 assert( p != nullptr );
229 return p->m_Data.first;
232 pair_ptr operator ->() const
234 typename iterator_base::value_ptr p = iterator_base::operator ->();
235 return p ? &(p->m_Data) : nullptr;
238 pair_ref operator *() const
240 typename iterator_base::value_ref p = iterator_base::operator *();
244 value_ref val() const
246 typename iterator_base::value_ptr p = iterator_base::operator ->();
247 assert( p != nullptr );
248 return p->m_Data.second;
252 iterator_type& operator ++()
254 iterator_base::operator ++();
259 bool operator ==(iterator_type<C> const& i ) const
261 return iterator_base::operator ==(i);
264 bool operator !=(iterator_type<C> const& i ) const
266 return iterator_base::operator !=(i);
274 The forward iterator for Michael's list has some features:
275 - it has no post-increment operator
276 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
277 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
278 may be thrown if a limit of guard count per thread is exceeded.
279 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
280 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
281 deleting operations it is no guarantee that you iterate all item in the list.
283 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
284 for debug purpose only.
286 The iterator interface to access item data:
287 - <tt> operator -> </tt> - returns a pointer to \ref value_type for iterator
288 - <tt> operator *</tt> - returns a reference (a const reference for \p const_iterator) to \ref value_type for iterator
289 - <tt> const key_type& key() </tt> - returns a key reference for iterator
290 - <tt> mapped_type& val() </tt> - retuns a value reference for iterator (const reference for \p const_iterator)
292 For both functions the iterator should not be equal to <tt> end() </tt>
294 typedef iterator_type<false> iterator;
296 /// Const forward iterator
298 For iterator's features and requirements see \ref iterator
300 typedef iterator_type<true> const_iterator;
302 /// Returns a forward iterator addressing the first element in a list
304 For empty list \code begin() == end() \endcode
308 return iterator( head() );
311 /// Returns an iterator that addresses the location succeeding the last element in a list
313 Do not use the value returned by <tt>end</tt> function to access any item.
314 Internally, <tt>end</tt> returning value equals to \p nullptr.
316 The returned value can be used only to control reaching the end of the list.
317 For empty list \code begin() == end() \endcode
324 /// Returns a forward const iterator addressing the first element in a list
326 const_iterator begin() const
328 return const_iterator( head() );
330 const_iterator cbegin() const
332 return const_iterator( head() );
336 /// Returns an const iterator that addresses the location succeeding the last element in a list
338 const_iterator end() const
340 return const_iterator();
342 const_iterator cend() const
344 return const_iterator();
349 /// Default constructor
351 Initializes empty list
365 /// Inserts new node with key and default value
367 The function creates a node with \p key and default value, and then inserts the node created into the list.
370 - The \p key_type should be constructible from value of type \p K.
371 In trivial case, \p K is equal to \p key_type.
372 - The \p mapped_type should be default-constructible.
374 Returns \p true if inserting successful, \p false otherwise.
376 template <typename K>
377 bool insert( const K& key )
379 return insert_at( head(), key );
382 /// Inserts new node with a key and a value
384 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
387 - The \p key_type should be constructible from \p key of type \p K.
388 - The \p mapped_type should be constructible from \p val of type \p V.
390 Returns \p true if inserting successful, \p false otherwise.
392 template <typename K, typename V>
393 bool insert( const K& key, const V& val )
395 // We cannot use insert with functor here
396 // because we cannot lock inserted node for updating
397 // Therefore, we use separate function
398 return insert_at( head(), key, val );
401 /// Inserts new node and initialize it by a functor
403 This function inserts new node with key \p key and if inserting is successful then it calls
404 \p func functor with signature
407 void operator()( value_type& item );
411 The argument \p item of user-defined functor \p func is the reference
412 to the item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
413 User-defined functor \p func should guarantee that during changing item's value no any other changes
414 could be made on this list's item by concurrent threads.
415 The user-defined functor is called only if inserting is successful.
417 The \p key_type should be constructible from value of type \p K.
419 The function allows to split creating of new item into two part:
420 - create a new item from \p key;
421 - insert the new item into the list;
422 - if inserting is successful, initialize the value of item by calling \p func functor
424 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
425 it is preferable that the initialization should be completed only if inserting is successful.
427 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
429 template <typename K, typename Func>
430 bool insert_with( const K& key, Func func )
432 return insert_with_at( head(), key, func );
435 /// Updates data by \p key
437 The operation performs inserting or replacing the element with lock-free manner.
439 If the \p key not found in the list, then the new item created from \p key
440 will be inserted iff \p bAllowInsert is \p true.
441 (note that in this case the \ref key_type should be constructible from type \p K).
442 Otherwise, if \p key is found, the functor \p func is called with item found.
444 The functor \p Func signature is:
447 void operator()( bool bNew, value_type& item );
451 - \p bNew - \p true if the item has been inserted, \p false otherwise
452 - \p item - the item found or inserted
454 The functor may change any fields of the \p item.second of \p mapped_type;
455 however, \p func must guarantee that during changing no any other modifications
456 could be made on this item by concurrent threads.
458 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
459 \p second is true if new item has been added or \p false if the item with \p key
462 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
464 template <typename K, typename Func>
465 std::pair<bool, bool> update( K const& key, Func f, bool bAllowInsert = true )
467 return update_at( head(), key, f, bAllowInsert );
470 template <typename K, typename Func>
471 CDS_DEPRECATED("ensure() is deprecated, use update()")
472 std::pair<bool, bool> ensure( K const& key, Func f )
474 return update( key, f, true );
478 /// Inserts a new node using move semantics
480 \p key_type field of new item is constructed from \p key argument,
481 \p mapped_type field is done from \p args.
483 Returns \p true if inserting successful, \p false otherwise.
485 template <typename K, typename... Args>
486 bool emplace( K&& key, Args&&... args )
488 return emplace_at( head(), std::forward<K>(key), std::forward<Args>(args)... );
491 /// Deletes \p key from the list
492 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_val
494 Returns \p true if \p key is found and has been deleted, \p false otherwise
496 template <typename K>
497 bool erase( K const& key )
499 return erase_at( head(), key, intrusive_key_comparator() );
502 /// Deletes the item from the list using \p pred predicate for searching
504 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_val "erase(K const&)"
505 but \p pred is used for key comparing.
506 \p Less functor has the interface like \p std::less.
507 \p pred must imply the same element order as the comparator used for building the list.
509 template <typename K, typename Less>
510 bool erase_with( K const& key, Less pred )
513 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type() );
516 /// Deletes \p key from the list
517 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_func
518 The function searches an item with key \p key, calls \p f functor
519 and deletes the item. If \p key is not found, the functor is not called.
521 The functor \p Func interface:
524 void operator()(value_type& val) { ... }
528 Return \p true if key is found and deleted, \p false otherwise
532 template <typename K, typename Func>
533 bool erase( K const& key, Func f )
535 return erase_at( head(), key, intrusive_key_comparator(), f );
538 /// Deletes the item from the list using \p pred predicate for searching
540 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_func "erase(K const&, Func)"
541 but \p pred is used for key comparing.
542 \p Less functor has the interface like \p std::less.
543 \p pred must imply the same element order as the comparator used for building the list.
545 template <typename K, typename Less, typename Func>
546 bool erase_with( K const& key, Less pred, Func f )
549 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
552 /// Extracts the item from the list with specified \p key
553 /** \anchor cds_nonintrusive_MichaelKVList_hp_extract
554 The function searches an item with key equal to \p key,
555 unlinks it from the list, and returns it as \p guarded_ptr.
556 If \p key is not found the function returns an empty guarded pointer.
558 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
560 The \p disposer specified in \p Traits class template parameter is called automatically
561 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
562 will be destroyed or released.
563 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
567 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
571 ord_list::guarded_ptr gp(theList.extract( 5 ));
576 // Destructor of gp releases internal HP guard
580 template <typename K>
581 guarded_ptr extract( K const& key )
584 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
588 /// Extracts the item from the list with comparing functor \p pred
590 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_extract "extract(K const&)"
591 but \p pred predicate is used for key comparing.
593 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
595 \p pred must imply the same element order as the comparator used for building the list.
597 template <typename K, typename Less>
598 guarded_ptr extract_with( K const& key, Less pred )
602 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
606 /// Checks whether the list contains \p key
608 The function searches the item with key equal to \p key
609 and returns \p true if it is found, and \p false otherwise.
611 template <typename Q>
612 bool contains( Q const& key )
614 return find_at( head(), key, intrusive_key_comparator() );
617 template <typename Q>
618 CDS_DEPRECATED("deprecated, use contains()")
619 bool find( Q const& key )
621 return contains( key );
625 /// Checks whether the map contains \p key using \p pred predicate for searching
627 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
628 \p Less functor has the interface like \p std::less.
629 \p Less must imply the same element order as the comparator used for building the list.
631 template <typename Q, typename Less>
632 bool contains( Q const& key, Less pred )
635 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
638 template <typename Q, typename Less>
639 CDS_DEPRECATED("deprecated, use contains()")
640 bool find_with( Q const& key, Less pred )
643 return contains( key, pred );
647 /// Finds the key \p key and performs an action with it
648 /** \anchor cds_nonintrusive_MichaelKVList_hp_find_func
649 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
650 The interface of \p Func functor is:
653 void operator()( value_type& item );
656 where \p item is the item found.
658 The functor may change <tt>item.second</tt> that is reference to value of node.
659 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
660 The function does not serialize simultaneous access to the list \p item. If such access is
661 possible you must provide your own synchronization schema to exclude unsafe item modifications.
663 The function returns \p true if \p key is found, \p false otherwise.
665 template <typename Q, typename Func>
666 bool find( Q const& key, Func f )
668 return find_at( head(), key, intrusive_key_comparator(), f );
671 /// Finds the key \p val using \p pred predicate for searching
673 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_find_func "find(Q&, Func)"
674 but \p pred is used for key comparing.
675 \p Less functor has the interface like \p std::less.
676 \p pred must imply the same element order as the comparator used for building the list.
678 template <typename Q, typename Less, typename Func>
679 bool find_with( Q const& key, Less pred, Func f )
682 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
685 /// Finds the \p key and return the item found
686 /** \anchor cds_nonintrusive_MichaelKVList_hp_get
687 The function searches the item with key equal to \p key
688 and returns it as \p guarded_ptr.
689 If \p key is not found the function returns an empty guarded pointer.
691 The \p disposer specified in \p Traits class template parameter is called
692 by garbage collector \p GC automatically when returned \p guarded_ptr object
693 will be destroyed or released.
694 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
698 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
702 ord_list::guarded_ptr gp(theList.get( 5 ));
707 // Destructor of guarded_ptr releases internal HP guard
711 Note the compare functor specified for class \p Traits template parameter
712 should accept a parameter of type \p K that can be not the same as \p key_type.
714 template <typename K>
715 guarded_ptr get( K const& key )
718 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
722 /// Finds the \p key and return the item found
724 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_get "get( guarded_ptr& ptr, K const&)"
725 but \p pred is used for comparing the keys.
727 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
729 \p pred must imply the same element order as the comparator used for building the list.
731 template <typename K, typename Less>
732 guarded_ptr get_with( K const& key, Less pred )
736 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
740 /// Checks if the list is empty
743 return base_class::empty();
746 /// Returns list's item count
748 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
749 this function always returns 0.
751 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
752 is empty. To check list emptyness use \p empty() method.
756 return base_class::size();
767 bool insert_node_at( head_type& refHead, node_type * pNode )
769 assert( pNode != nullptr );
770 scoped_node_ptr p( pNode );
771 if ( base_class::insert_at( refHead, *pNode )) {
778 template <typename K>
779 bool insert_at( head_type& refHead, const K& key )
781 return insert_node_at( refHead, alloc_node( key ));
784 template <typename K, typename V>
785 bool insert_at( head_type& refHead, const K& key, const V& val )
787 return insert_node_at( refHead, alloc_node( key, val ));
790 template <typename K, typename Func>
791 bool insert_with_at( head_type& refHead, const K& key, Func f )
793 scoped_node_ptr pNode( alloc_node( key ));
795 if ( base_class::insert_at( refHead, *pNode, [&f](node_type& node){ f( node.m_Data ); })) {
802 template <typename K, typename... Args>
803 bool emplace_at( head_type& refHead, K&& key, Args&&... args )
805 return insert_node_at( refHead, alloc_node( std::forward<K>(key), std::forward<Args>(args)... ));
808 template <typename K, typename Func>
809 std::pair<bool, bool> update_at( head_type& refHead, const K& key, Func f, bool bAllowInsert )
811 scoped_node_ptr pNode( alloc_node( key ));
813 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
814 [&f]( bool bNew, node_type& node, node_type& ){ f( bNew, node.m_Data ); },
816 if ( ret.first && ret.second )
822 template <typename K, typename Compare>
823 bool erase_at( head_type& refHead, K const& key, Compare cmp )
825 return base_class::erase_at( refHead, key, cmp );
828 template <typename K, typename Compare, typename Func>
829 bool erase_at( head_type& refHead, K const& key, Compare cmp, Func f )
831 return base_class::erase_at( refHead, key, cmp, [&f]( node_type const & node ){ f( const_cast<value_type&>(node.m_Data)); });
833 template <typename K, typename Compare>
834 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
836 return base_class::extract_at( refHead, guard, key, cmp );
839 template <typename K, typename Compare>
840 bool find_at( head_type& refHead, K const& key, Compare cmp )
842 return base_class::find_at( refHead, key, cmp );
845 template <typename K, typename Compare, typename Func>
846 bool find_at( head_type& refHead, K& key, Compare cmp, Func f )
848 return base_class::find_at( refHead, key, cmp, [&f](node_type& node, K const&){ f( node.m_Data ); });
851 template <typename K, typename Compare>
852 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
854 return base_class::get_at( refHead, guard, key, cmp );
860 }} // namespace cds::container
862 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_KVLIST_H