3 #ifndef __CDS_CONTAINER_IMPL_MICHAEL_KVLIST_H
4 #define __CDS_CONTAINER_IMPL_MICHAEL_KVLIST_H
7 #include <functional> // ref
8 #include <cds/details/functor_wrapper.h>
9 #include <cds/container/details/guarded_ptr_cast.h>
11 namespace cds { namespace container {
13 /// Michael's ordered list (key-value pair)
14 /** @ingroup cds_nonintrusive_list
15 \anchor cds_nonintrusive_MichaelKVList_gc
17 This is key-value variation of non-intrusive MichaelList.
18 Like standard container, this implementation split a value stored into two part -
19 constant key and alterable value.
21 Usually, ordered single-linked list is used as a building block for the hash table implementation.
22 The complexity of searching is <tt>O(N)</tt>.
25 - \p GC - garbage collector used
26 - \p Key - key type of an item stored in the list. It should be copy-constructible
27 - \p Value - value type stored in a list
28 - \p Traits - type traits, default is michael_list::type_traits
30 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
31 argument. For example, the following traits-based declaration of gc::HP Michael's list
33 #include <cds/container/michael_kvlist_hp.h>
34 // Declare comparator for the item
36 int operator ()( int i1, int i2 )
42 // Declare type_traits
43 struct my_traits: public cds::container::michael_list::type_traits
45 typedef my_compare compare;
48 // Declare traits-based list
49 typedef cds::container::MichaelKVList< cds::gc::HP, int, int, my_traits > traits_based_list;
52 is equivalent for the following option-based list
54 #include <cds/container/michael_kvlist_hp.h>
56 // my_compare is the same
58 // Declare option-based list
59 typedef cds::container::MichaelKVList< cds::gc::HP, int, int,
60 typename cds::container::michael_list::make_traits<
61 cds::container::opt::compare< my_compare > // item comparator option
66 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
67 - opt::compare - key comparison functor. No default functor is provided.
68 If the option is not specified, the opt::less is used.
69 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
70 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
71 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
72 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
73 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
74 or opt::v::sequential_consistent (sequentially consisnent memory model).
77 There are different specializations of this template for each garbage collecting schema used.
78 You should include appropriate .h-file depending on GC you are using:
79 - for gc::HP: \code #include <cds/container/michael_kvlist_hp.h> \endcode
80 - for gc::PTB: \code #include <cds/container/michael_kvlist_ptb.h> \endcode
81 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_kvlist_rcu.h> \endcode
82 - for gc::nogc: \code #include <cds/container/michael_kvlist_nogc.h> \endcode
88 #ifdef CDS_DOXYGEN_INVOKED
89 typename Traits = michael_list::type_traits
95 #ifdef CDS_DOXYGEN_INVOKED
96 protected intrusive::MichaelList< GC, implementation_defined, Traits >
98 protected details::make_michael_kvlist< GC, Key, Value, Traits >::type
102 typedef details::make_michael_kvlist< GC, Key, Value, Traits > options;
103 typedef typename options::type base_class;
107 #ifdef CDS_DOXYGEN_INVOKED
108 typedef Key key_type ; ///< Key type
109 typedef Value mapped_type ; ///< Type of value stored in the list
110 typedef std::pair<key_type const, mapped_type> value_type ; ///< key/value pair stored in the list
112 typedef typename options::key_type key_type;
113 typedef typename options::value_type mapped_type;
114 typedef typename options::pair_type value_type;
117 typedef typename base_class::gc gc ; ///< Garbage collector used
118 typedef typename base_class::back_off back_off ; ///< Back-off strategy used
119 typedef typename options::allocator_type allocator_type ; ///< Allocator type used for allocate/deallocate the nodes
120 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
121 typedef typename options::key_comparator key_comparator ; ///< key comparison functor
122 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
126 typedef typename base_class::value_type node_type;
127 typedef typename options::cxx_allocator cxx_allocator;
128 typedef typename options::node_deallocator node_deallocator;
129 typedef typename options::type_traits::compare intrusive_key_comparator;
131 typedef typename base_class::atomic_node_ptr head_type;
136 typedef cds::gc::guarded_ptr< gc, node_type, value_type, details::guarded_ptr_cast_map<node_type, value_type> > guarded_ptr;
140 template <typename K>
141 static node_type * alloc_node(const K& key)
143 return cxx_allocator().New( key );
146 template <typename K, typename V>
147 static node_type * alloc_node( const K& key, const V& val )
149 return cxx_allocator().New( key, val );
152 template <typename K, typename... Args>
153 static node_type * alloc_node( K&& key, Args&&... args )
155 return cxx_allocator().MoveNew( std::forward<K>(key), std::forward<Args>(args)...);
158 static void free_node( node_type * pNode )
160 cxx_allocator().Delete( pNode );
163 struct node_disposer {
164 void operator()( node_type * pNode )
169 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
173 return base_class::m_pHead;
176 head_type const& head() const
178 return base_class::m_pHead;
184 template <bool IsConst>
185 class iterator_type: protected base_class::template iterator_type<IsConst>
187 typedef typename base_class::template iterator_type<IsConst> iterator_base;
189 iterator_type( head_type const& pNode )
190 : iterator_base( pNode )
193 friend class MichaelKVList;
196 typedef typename cds::details::make_const_type<mapped_type, IsConst>::reference value_ref;
197 typedef typename cds::details::make_const_type<mapped_type, IsConst>::pointer value_ptr;
199 typedef typename cds::details::make_const_type<value_type, IsConst>::reference pair_ref;
200 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer pair_ptr;
205 iterator_type( iterator_type const& src )
206 : iterator_base( src )
209 key_type const& key() const
211 typename iterator_base::value_ptr p = iterator_base::operator ->();
212 assert( p != nullptr );
213 return p->m_Data.first;
216 pair_ptr operator ->() const
218 typename iterator_base::value_ptr p = iterator_base::operator ->();
219 return p ? &(p->m_Data) : nullptr;
222 pair_ref operator *() const
224 typename iterator_base::value_ref p = iterator_base::operator *();
228 value_ref val() const
230 typename iterator_base::value_ptr p = iterator_base::operator ->();
231 assert( p != nullptr );
232 return p->m_Data.second;
236 iterator_type& operator ++()
238 iterator_base::operator ++();
243 bool operator ==(iterator_type<C> const& i ) const
245 return iterator_base::operator ==(i);
248 bool operator !=(iterator_type<C> const& i ) const
250 return iterator_base::operator !=(i);
258 The forward iterator for Michael's list has some features:
259 - it has no post-increment operator
260 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
261 For some GC (gc::HP, gc::HRC), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
262 may be thrown if a limit of guard count per thread is exceeded.
263 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
264 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
265 deleting operations it is no guarantee that you iterate all item in the list.
267 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
268 for debug purpose only.
270 The iterator interface to access item data:
271 - <tt> operator -> </tt> - returns a pointer to \ref value_type for iterator
272 - <tt> operator *</tt> - returns a reference (a const reference for \p const_iterator) to \ref value_type for iterator
273 - <tt> const key_type& key() </tt> - returns a key reference for iterator
274 - <tt> mapped_type& val() </tt> - retuns a value reference for iterator (const reference for \p const_iterator)
276 For both functions the iterator should not be equal to <tt> end() </tt>
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
310 const_iterator begin() const
312 return const_iterator( head() );
314 const_iterator cbegin()
316 return const_iterator( head() );
320 /// Returns an const iterator that addresses the location succeeding the last element in a list
322 const_iterator end() const
324 return const_iterator();
326 const_iterator cend()
328 return const_iterator();
333 /// Default constructor
335 Initializes empty list
349 /// Inserts new node with key and default value
351 The function creates a node with \p key and default value, and then inserts the node created into the list.
354 - The \ref key_type should be constructible from value of type \p K.
355 In trivial case, \p K is equal to \ref key_type.
356 - The \ref mapped_type should be default-constructible.
358 Returns \p true if inserting successful, \p false otherwise.
360 template <typename K>
361 bool insert( const K& key )
363 return insert_at( head(), key );
366 /// Inserts new node with a key and a value
368 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
371 - The \ref key_type should be constructible from \p key of type \p K.
372 - The \ref mapped_type should be constructible from \p val of type \p V.
374 Returns \p true if inserting successful, \p false otherwise.
376 template <typename K, typename V>
377 bool insert( const K& key, const V& val )
379 // We cannot use insert with functor here
380 // because we cannot lock inserted node for updating
381 // Therefore, we use separate function
382 return insert_at( head(), key, val );
385 /// Inserts new node and initialize it by a functor
387 This function inserts new node with key \p key and if inserting is successful then it calls
388 \p func functor with signature
391 void operator()( value_type& item );
395 The argument \p item of user-defined functor \p func is the reference
396 to the list's item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
397 User-defined functor \p func should guarantee that during changing item's value no any other changes
398 could be made on this list's item by concurrent threads.
399 The user-defined functor can be passed by reference using \p std::ref
400 and it is called only if inserting is successful.
402 The key_type should be constructible from value of type \p K.
404 The function allows to split creating of new item into two part:
405 - create item from \p key;
406 - insert new item into the list;
407 - if inserting is successful, initialize the value of item by calling \p func functor
409 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
410 it is preferable that the initialization should be completed only if inserting is successful.
412 template <typename K, typename Func>
413 bool insert_key( const K& key, Func func )
415 return insert_key_at( head(), key, func );
418 /// Ensures that the \p key exists in the list
420 The operation performs inserting or changing data with lock-free manner.
422 If the \p key not found in the list, then the new item created from \p key
423 is inserted into the list (note that in this case the \ref key_type should be
424 copy-constructible from type \p K).
425 Otherwise, the functor \p func is called with item found.
426 The functor \p Func may be a function with signature:
428 void func( bool bNew, value_type& item );
433 void operator()( bool bNew, value_type& item );
438 - \p bNew - \p true if the item has been inserted, \p false otherwise
439 - \p item - item of the list
441 The functor may change any fields of the \p item.second that is \ref mapped_type;
442 however, \p func must guarantee that during changing no any other modifications
443 could be made on this item by concurrent threads.
445 You may pass \p func argument by reference using \p std::ref
447 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
448 \p second is true if new item has been added or \p false if the item with \p key
449 already is in the list.
451 template <typename K, typename Func>
452 std::pair<bool, bool> ensure( const K& key, Func f )
454 return ensure_at( head(), key, f );
457 /// Inserts data of type \ref mapped_type constructed with <tt>std::forward<Args>(args)...</tt>
459 Returns \p true if inserting successful, \p false otherwise.
461 template <typename K, typename... Args>
462 bool emplace( K&& key, Args&&... args )
464 return emplace_at( head(), std::forward<K>(key), std::forward<Args>(args)... );
467 /// Deletes \p key from the list
468 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_val
470 Returns \p true if \p key is found and has been deleted, \p false otherwise
472 template <typename K>
473 bool erase( K const& key )
475 return erase_at( head(), key, intrusive_key_comparator() );
478 /// Deletes the item from the list using \p pred predicate for searching
480 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_erase_val "erase(K const&)"
481 but \p pred is used for key comparing.
482 \p Less functor has the interface like \p std::less.
483 \p pred must imply the same element order as the comparator used for building the list.
485 template <typename K, typename Less>
486 bool erase_with( K const& key, Less pred )
488 return erase_at( head(), key, typename options::template less_wrapper<Less>::type() );
491 /// Deletes \p key from the list
492 /** \anchor cds_nonintrusive_MichaelKVList_hp_erase_func
493 The function searches an item with key \p key, calls \p f functor
494 and deletes the item. If \p key is not found, the functor is not called.
496 The functor \p Func interface:
499 void operator()(value_type& val) { ... }
502 The functor may be passed by reference with <tt>boost:ref</tt>
504 Return \p true if key is found and deleted, \p false otherwise
508 template <typename K, typename Func>
509 bool erase( K const& key, Func f )
511 return erase_at( head(), key, intrusive_key_comparator(), f );
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_func "erase(K const&, Func)"
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, typename Func>
522 bool erase_with( K const& key, Less pred, Func f )
524 return erase_at( head(), key, typename options::template less_wrapper<Less>::type(), f );
527 /// Extracts the item from the list with specified \p key
528 /** \anchor cds_nonintrusive_MichaelKVList_hp_extract
529 The function searches an item with key equal to \p key,
530 unlinks it from the list, and returns it in \p dest parameter.
531 If the item with key equal to \p key is not found the function returns \p false.
533 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
535 The \ref disposer specified in \p Traits class template parameter is called automatically
536 by garbage collector \p GC specified in class' template parameters when returned \ref guarded_ptr object
537 will be destroyed or released.
538 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
542 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
546 ord_list::guarded_ptr gp;
547 theList.extract( gp, 5 );
551 // Destructor of gp releases internal HP guard
555 template <typename K>
556 bool extract( guarded_ptr& dest, K const& key )
558 return extract_at( head(), dest.guard(), key, intrusive_key_comparator() );
561 /// Extracts the item from the list with comparing functor \p pred
563 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_extract "extract(guarded_ptr&, K const&)"
564 but \p pred predicate is used for key comparing.
566 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
568 \p pred must imply the same element order as the comparator used for building the list.
570 template <typename K, typename Less>
571 bool extract_with( guarded_ptr& dest, K const& key, Less pred )
573 return extract_at( head(), dest.guard(), key, typename options::template less_wrapper<Less>::type() );
576 /// Finds the key \p key
577 /** \anchor cds_nonintrusive_MichaelKVList_hp_find_val
578 The function searches the item with key equal to \p key
579 and returns \p true if it is found, and \p false otherwise
581 template <typename Q>
582 bool find( Q const& key )
584 return find_at( head(), key, intrusive_key_comparator() );
587 /// Finds the key \p val using \p pred predicate for searching
589 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_find_val "find(Q const&)"
590 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 find_with( Q const& key, Less pred )
597 return find_at( head(), key, typename options::template less_wrapper<Less>::type() );
600 /// Finds the key \p key and performs an action with it
601 /** \anchor cds_nonintrusive_MichaelKVList_hp_find_func
602 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
603 The interface of \p Func functor is:
606 void operator()( value_type& item );
609 where \p item is the item found.
611 You may pass \p f argument by reference using \p std::ref
613 The functor may change <tt>item.second</tt> that is reference to value of node.
614 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
615 The function does not serialize simultaneous access to the list \p item. If such access is
616 possible you must provide your own synchronization schema to exclude unsafe item modifications.
618 The function returns \p true if \p key is found, \p false otherwise.
620 template <typename Q, typename Func>
621 bool find( Q const& key, Func f )
623 return find_at( head(), key, intrusive_key_comparator(), f );
626 /// Finds the key \p val using \p pred predicate for searching
628 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_find_func "find(Q&, Func)"
629 but \p pred is used for key comparing.
630 \p Less functor has the interface like \p std::less.
631 \p pred must imply the same element order as the comparator used for building the list.
633 template <typename Q, typename Less, typename Func>
634 bool find_with( Q const& key, Less pred, Func f )
636 return find_at( head(), key, typename options::template less_wrapper<Less>::type(), f );
639 /// Finds the \p key and return the item found
640 /** \anchor cds_nonintrusive_MichaelKVList_hp_get
641 The function searches the item with key equal to \p key
642 and assigns the item found to guarded pointer \p ptr.
643 The function returns \p true if \p key is found, and \p false otherwise.
644 If \p key is not found the \p ptr parameter is not changed.
646 The \ref disposer specified in \p Traits class template parameter is called
647 by garbage collector \p GC automatically when returned \ref guarded_ptr object
648 will be destroyed or released.
649 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
653 typedef cds::container::MichaelKVList< cds::gc::HP, int, foo, my_traits > ord_list;
657 ord_list::guarded_ptr gp;
658 if ( theList.get( gp, 5 )) {
662 // Destructor of guarded_ptr releases internal HP guard
666 Note the compare functor specified for class \p Traits template parameter
667 should accept a parameter of type \p K that can be not the same as \p key_type.
669 template <typename K>
670 bool get( guarded_ptr& ptr, K const& key )
672 return get_at( head(), ptr.guard(), key, intrusive_key_comparator() );
675 /// Finds the \p key and return the item found
677 The function is an analog of \ref cds_nonintrusive_MichaelKVList_hp_get "get( guarded_ptr& ptr, K const&)"
678 but \p pred is used for comparing the keys.
680 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
682 \p pred must imply the same element order as the comparator used for building the list.
684 template <typename K, typename Less>
685 bool get_with( guarded_ptr& ptr, K const& key, Less pred )
687 return get_at( head(), ptr.guard(), key, typename options::template less_wrapper<Less>::type() );
690 /// Checks if the list is empty
693 return base_class::empty();
696 /// Returns list's item count
698 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
699 this function always returns 0.
701 <b>Warning</b>: even if you use real item counter and it returns 0, this fact is not mean that the list
702 is empty. To check list emptyness use \ref empty() method.
706 return base_class::size();
711 Post-condition: the list is empty
720 bool insert_node_at( head_type& refHead, node_type * pNode )
722 assert( pNode != nullptr );
723 scoped_node_ptr p( pNode );
724 if ( base_class::insert_at( refHead, *pNode )) {
731 template <typename K>
732 bool insert_at( head_type& refHead, const K& key )
734 return insert_node_at( refHead, alloc_node( key ));
737 template <typename K, typename V>
738 bool insert_at( head_type& refHead, const K& key, const V& val )
740 return insert_node_at( refHead, alloc_node( key, val ));
743 template <typename K, typename Func>
744 bool insert_key_at( head_type& refHead, const K& key, Func f )
746 scoped_node_ptr pNode( alloc_node( key ));
748 if ( base_class::insert_at( refHead, *pNode, [&f](node_type& node){ f( node.m_Data ); })) {
755 template <typename K, typename... Args>
756 bool emplace_at( head_type& refHead, K&& key, Args&&... args )
758 return insert_node_at( refHead, alloc_node( std::forward<K>(key), std::forward<Args>(args)... ));
761 template <typename K, typename Func>
762 std::pair<bool, bool> ensure_at( head_type& refHead, const K& key, Func f )
764 scoped_node_ptr pNode( alloc_node( key ));
766 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
767 [&f]( bool bNew, node_type& node, node_type& ){ f( bNew, node.m_Data ); });
768 if ( ret.first && ret.second )
774 template <typename K, typename Compare>
775 bool erase_at( head_type& refHead, K const& key, Compare cmp )
777 return base_class::erase_at( refHead, key, cmp );
780 template <typename K, typename Compare, typename Func>
781 bool erase_at( head_type& refHead, K const& key, Compare cmp, Func f )
783 return base_class::erase_at( refHead, key, cmp, [&f]( node_type const & node ){ f( const_cast<value_type&>(node.m_Data)); });
785 template <typename K, typename Compare>
786 bool extract_at( head_type& refHead, typename gc::Guard& dest, K const& key, Compare cmp )
788 return base_class::extract_at( refHead, dest, key, cmp );
791 template <typename K, typename Compare>
792 bool find_at( head_type& refHead, K const& key, Compare cmp )
794 return base_class::find_at( refHead, key, cmp );
797 template <typename K, typename Compare, typename Func>
798 bool find_at( head_type& refHead, K& key, Compare cmp, Func f )
800 return base_class::find_at( refHead, key, cmp, [&f](node_type& node, K const&){ f( node.m_Data ); });
803 template <typename K, typename Compare>
804 bool get_at( head_type& refHead, typename gc::Guard& guard, K const& key, Compare cmp )
806 return base_class::get_at( refHead, guard, key, cmp );
812 }} // namespace cds::container
814 #endif // #ifndef __CDS_CONTAINER_IMPL_MICHAEL_KVLIST_H