2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
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_LIST_H
32 #define CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
39 /// Michael's ordered list
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_MichaelList_gc
43 Usually, ordered single-linked list is used as a building block for the hash table implementation.
44 The complexity of searching is <tt>O(N)</tt>, where \p N is the item count in the list, not in the
48 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
50 This class is non-intrusive version of cds::intrusive::MichaelList class
53 - \p GC - garbage collector used
54 - \p T - type stored in the list. The type must be default- and copy-constructible.
55 - \p Traits - type traits, default is \p michael_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 MichaelKVList is a key-value version of Michael's non-intrusive list that is closer to the C++ std library approach.
64 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
65 argument. For example, the following traits-based declaration of gc::HP Michael's list
67 #include <cds/container/michael_list_hp.h>
68 // Declare comparator for the item
70 int operator ()( int i1, int i2 )
77 struct my_traits: public cds::container::michael_list::traits
79 typedef my_compare compare;
82 // Declare traits-based list
83 typedef cds::container::MichaelList< cds::gc::HP, int, my_traits > traits_based_list;
86 is equivalent for the following option-based list
88 #include <cds/container/michael_list_hp.h>
90 // my_compare is the same
92 // Declare option-based list
93 typedef cds::container::MichaelList< cds::gc::HP, int,
94 typename cds::container::michael_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/michael_list_hp.h> \endcode
104 - for gc::DHP: \code #include <cds/container/michael_list_dhp.h> \endcode
105 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_list_rcu.h> \endcode
106 - for gc::nogc: \code #include <cds/container/michael_list_nogc.h> \endcode
111 #ifdef CDS_DOXYGEN_INVOKED
112 typename Traits = michael_list::traits
118 #ifdef CDS_DOXYGEN_INVOKED
119 protected intrusive::MichaelList< GC, T, Traits >
121 protected details::make_michael_list< GC, T, Traits >::type
125 typedef details::make_michael_list< GC, T, Traits > maker;
126 typedef typename maker::type base_class;
130 typedef T value_type; ///< Type of value stored in the list
131 typedef Traits traits; ///< List traits
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 \p cds::opt::memory_model option
139 typedef typename base_class::stat stat; ///< Internal statistics
141 static constexpr const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
144 // Rebind traits (split-list support)
145 template <typename... Options>
146 struct rebind_traits {
150 , typename cds::opt::make_options< traits, Options...>::type
155 template <typename Stat>
156 using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
161 typedef typename base_class::value_type node_type;
162 typedef typename maker::cxx_allocator cxx_allocator;
163 typedef typename maker::node_deallocator node_deallocator;
164 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
166 typedef typename base_class::atomic_node_ptr head_type;
168 struct node_disposer {
169 void operator()( node_type * pNode )
174 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
179 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
183 template <bool IsConst>
184 class iterator_type: protected base_class::template iterator_type<IsConst>
186 typedef typename base_class::template iterator_type<IsConst> iterator_base;
188 iterator_type( head_type const& pNode )
189 : iterator_base( pNode )
192 friend class MichaelList;
195 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
196 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
201 iterator_type( iterator_type const& src )
202 : iterator_base( src )
205 value_ptr operator ->() const
207 typename iterator_base::value_ptr p = iterator_base::operator ->();
208 return p ? &(p->m_Value) : nullptr;
211 value_ref operator *() const
213 return (iterator_base::operator *()).m_Value;
217 iterator_type& operator ++()
219 iterator_base::operator ++();
224 bool operator ==(iterator_type<C> const& i ) const
226 return iterator_base::operator ==(i);
229 bool operator !=(iterator_type<C> const& i ) const
231 return iterator_base::operator !=(i);
237 ///@name Forward iterators (only for debugging purpose)
241 The forward iterator for Michael's list has some features:
242 - it has no post-increment operator
243 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
244 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
245 may be thrown if a limit of guard count per thread is exceeded.
246 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
247 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
248 deleting operations it is no guarantee that you iterate all item in the list.
249 Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread.
251 @warning Use this iterator on the concurrent container for debugging purpose only.
253 typedef iterator_type<false> iterator;
255 /// Const forward iterator
257 For iterator's features and requirements see \ref iterator
259 typedef iterator_type<true> const_iterator;
261 /// Returns a forward iterator addressing the first element in a list
263 For empty list \code begin() == end() \endcode
267 return iterator( head());
270 /// Returns an iterator that addresses the location succeeding the last element in a list
272 Do not use the value returned by <tt>end</tt> function to access any item.
273 Internally, <tt>end</tt> returning value equals to \p nullptr.
275 The returned value can be used only to control reaching the end of the list.
276 For empty list \code begin() == end() \endcode
283 /// Returns a forward const iterator addressing the first element in a list
284 const_iterator begin() const
286 return const_iterator( head());
289 /// Returns a forward const iterator addressing the first element in a list
290 const_iterator cbegin() const
292 return const_iterator( head());
295 /// Returns an const iterator that addresses the location succeeding the last element in a list
296 const_iterator end() const
298 return const_iterator();
301 /// Returns an const iterator that addresses the location succeeding the last element in a list
302 const_iterator cend() const
304 return const_iterator();
309 /// Default constructor
311 Initialize empty list
317 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
318 explicit MichaelList( Stat& st )
334 The function creates a node with copy of \p val value
335 and then inserts the node created into the list.
337 The type \p Q should contain least the complete key of the node.
338 The object of \ref value_type should be constructible from \p val of type \p Q.
339 In trivial case, \p Q is equal to \ref value_type.
341 Returns \p true if inserting successful, \p false otherwise.
343 template <typename Q>
344 bool insert( Q&& val )
346 return insert_at( head(), std::forward<Q>( val ));
351 This function inserts new node with default-constructed value and then it calls
352 \p func functor with signature
353 \code void func( value_type& itemValue ) ;\endcode
355 The argument \p itemValue of user-defined functor \p func is the reference
356 to the list's item inserted. User-defined functor \p func should guarantee that during changing
357 item's value no any other changes could be made on this list's item by concurrent threads.
358 The user-defined functor is called only if inserting is success.
360 The type \p Q should contain the complete key of the node.
361 The object of \p value_type should be constructible from \p key of type \p Q.
363 The function allows to split creating of new item into two part:
364 - create item from \p key with initializing key-fields only;
365 - insert new item into the list;
366 - if inserting is successful, initialize non-key fields of item by calling \p func functor
368 The method can be useful if complete initialization of object of \p value_type is heavyweight and
369 it is preferable that the initialization should be completed only if inserting is successful.
371 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
373 template <typename Q, typename Func>
374 bool insert( Q&& key, Func func )
376 return insert_at( head(), std::forward<Q>(key), func );
379 /// Updates data by \p key
381 The operation performs inserting or replacing the element with lock-free manner.
383 If the \p key not found in the list, then the new item created from \p key
384 will be inserted iff \p bAllowInsert is \p true.
385 Otherwise, if \p key is found, the functor \p func is called with item found.
387 The functor \p Func signature is:
390 void operator()( bool bNew, value_type& item, Q const& key );
395 - \p bNew - \p true if the item has been inserted, \p false otherwise
396 - \p item - item of the list
397 - \p key - argument \p key passed into the \p %update() function
399 The functor may change non-key fields of the \p item; however, \p func must guarantee
400 that during changing no any other modifications could be made on this item by concurrent threads.
402 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
403 \p second is true if new item has been added or \p false if the item with \p key
406 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
408 template <typename Q, typename Func>
409 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
411 return update_at( head(), key, func, bAllowInsert );
414 template <typename Q, typename Func>
415 CDS_DEPRECATED("ensure() is deprecated, use update()")
416 std::pair<bool, bool> ensure( Q const& key, Func func )
418 return update( key, func );
422 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
424 Returns \p true if inserting successful, \p false otherwise.
426 template <typename... Args>
427 bool emplace( Args&&... args )
429 return emplace_at( head(), std::forward<Args>(args)... );
432 /// Delete \p key from the list
433 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
434 Since the key of MichaelList's item type \p value_type is not explicitly specified,
435 template parameter \p Q sould contain the complete key to search in the list.
436 The list item comparator should be able to compare the type \p value_type
439 Return \p true if key is found and deleted, \p false otherwise
441 template <typename Q>
442 bool erase( Q const& key )
444 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
447 /// Deletes the item from the list using \p pred predicate for searching
449 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
450 but \p pred is used for key comparing.
451 \p Less functor has the interface like \p std::less.
452 \p pred must imply the same element order as the comparator used for building the list.
454 template <typename Q, typename Less>
455 bool erase_with( Q const& key, Less pred )
458 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
461 /// Deletes \p key from the list
462 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
463 The function searches an item with key \p key, calls \p f functor with item found
464 and deletes it. If \p key is not found, the functor is not called.
466 The functor \p Func interface:
469 void operator()(const value_type& val) { ... }
473 Since the key of MichaelList's item type \p value_type is not explicitly specified,
474 template parameter \p Q should contain the complete key to search in the list.
475 The list item comparator should be able to compare the type \p value_type of list item
478 Return \p true if key is found and deleted, \p false otherwise
480 template <typename Q, typename Func>
481 bool erase( Q const& key, Func f )
483 return erase_at( head(), key, intrusive_key_comparator(), f );
486 /// Deletes the item from the list using \p pred predicate for searching
488 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
489 but \p pred is used for key comparing.
490 \p Less functor has the interface like \p std::less.
491 \p pred must imply the same element order as the comparator used for building the list.
493 template <typename Q, typename Less, typename Func>
494 bool erase_with( Q const& key, Less pred, Func f )
497 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
500 /// Extracts the item from the list with specified \p key
501 /** \anchor cds_nonintrusive_MichaelList_hp_extract
502 The function searches an item with key equal to \p key,
503 unlinks it from the list, and returns it as \p guarded_ptr.
504 If \p key is not found the function returns an empty guarded pointer.
506 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
508 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
512 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
516 ord_list::guarded_ptr gp(theList.extract( 5 ));
521 // Destructor of gp releases internal HP guard and frees the item
525 template <typename Q>
526 guarded_ptr extract( Q const& key )
528 return extract_at( head(), key, intrusive_key_comparator());
531 /// Extracts the item from the list with comparing functor \p pred
533 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(Q const&)"
534 but \p pred predicate is used for key comparing.
536 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
538 \p pred must imply the same element order as the comparator used for building the list.
540 template <typename Q, typename Less>
541 guarded_ptr extract_with( Q const& key, Less pred )
544 return extract_at( head(), key, typename maker::template less_wrapper<Less>::type());
547 /// Checks whether the list contains \p key
549 The function searches the item with key equal to \p key
550 and returns \p true if it is found, and \p false otherwise.
552 template <typename Q>
553 bool contains( Q const& key )
555 return find_at( head(), key, intrusive_key_comparator());
558 template <typename Q>
559 CDS_DEPRECATED("deprecated, use contains()")
560 bool find( Q const& key )
562 return contains( key );
566 /// Checks whether the list contains \p key using \p pred predicate for searching
568 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
569 \p Less functor has the interface like \p std::less.
570 \p pred must imply the same element order as the comparator used for building the list.
572 template <typename Q, typename Less>
573 bool contains( Q const& key, Less pred )
576 return find_at( head(), key, typename maker::template less_wrapper<Less>::type());
579 template <typename Q, typename Less>
580 CDS_DEPRECATED("deprecated, use contains()")
581 bool find_with( Q const& key, Less pred )
583 return contains( key, pred );
587 /// Finds \p key and perform an action with it
588 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
589 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
590 The interface of \p Func functor is:
593 void operator()( value_type& item, Q& key );
596 where \p item is the item found, \p key is the <tt>find</tt> function argument.
598 The functor may change non-key fields of \p item. Note that the function is only guarantee
599 that \p item cannot be deleted during functor is executing.
600 The function does not serialize simultaneous access to the list \p item. If such access is
601 possible you must provide your own synchronization schema to exclude unsafe item modifications.
603 The function returns \p true if \p key is found, \p false otherwise.
605 template <typename Q, typename Func>
606 bool find( Q& key, Func f )
608 return find_at( head(), key, intrusive_key_comparator(), f );
611 template <typename Q, typename Func>
612 bool find( Q const& key, Func f )
614 return find_at( head(), key, intrusive_key_comparator(), f );
618 /// Finds \p key using \p pred predicate for searching
620 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
621 but \p pred is used for key comparing.
622 \p Less functor has the interface like \p std::less.
623 \p pred must imply the same element order as the comparator used for building the list.
625 template <typename Q, typename Less, typename Func>
626 bool find_with( Q& key, Less pred, Func f )
629 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
632 template <typename Q, typename Less, typename Func>
633 bool find_with( Q const& key, Less pred, Func f )
636 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
640 /// Finds \p key and return the item found
642 The function searches the item with key equal to \p key
643 and returns it as \p guarded_ptr.
644 If \p key is not found the function returns an empty guarded pointer.
646 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
650 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
654 ord_list::guarded_ptr gp(theList.get( 5 ));
659 // Destructor of guarded_ptr releases internal HP guard and frees the item
663 Note the compare functor specified for class \p Traits template parameter
664 should accept a parameter of type \p Q that can be not the same as \p value_type.
666 template <typename Q>
667 guarded_ptr get( Q const& key )
669 return get_at( head(), key, intrusive_key_comparator());
672 /// Finds \p key and return the item found
674 The function is an analog of \p get( Q const&)
675 but \p pred is used for comparing the keys.
677 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
679 \p pred must imply the same element order as the comparator used for building the list.
681 template <typename Q, typename Less>
682 guarded_ptr get_with( Q const& key, Less pred )
685 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
688 /// Check if the list is empty
691 return base_class::empty();
694 /// Returns list's item count
696 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
697 this function always returns 0.
699 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
700 is empty. To check list emptyness use \p empty() method.
704 return base_class::size();
713 /// Returns const reference to internal statistics
714 stat const& statistics() const
716 return base_class::statistics();
721 static value_type& node_to_value( node_type& n )
725 static value_type const& node_to_value( node_type const& n )
730 template <typename Q>
731 static node_type * alloc_node( Q const& v )
733 return cxx_allocator().New( v );
736 template <typename... Args>
737 static node_type * alloc_node( Args&&... args )
739 return cxx_allocator().MoveNew( std::forward<Args>( args )... );
742 static void free_node( node_type * pNode )
744 cxx_allocator().Delete( pNode );
749 return base_class::m_pHead;
752 head_type const& head() const
754 return base_class::m_pHead;
757 bool insert_node( node_type * pNode )
759 return insert_node_at( head(), pNode );
762 bool insert_node_at( head_type& refHead, node_type * pNode )
765 scoped_node_ptr p(pNode);
766 if ( base_class::insert_at( refHead, *pNode )) {
774 template <typename Q>
775 bool insert_at( head_type& refHead, Q&& val )
777 return insert_node_at( refHead, alloc_node( std::forward<Q>(val)));
780 template <typename Q, typename Func>
781 bool insert_at( head_type& refHead, Q&& key, Func f )
783 scoped_node_ptr pNode( alloc_node( std::forward<Q>( key )));
785 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node)); } )) {
792 template <typename... Args>
793 bool emplace_at( head_type& refHead, Args&&... args )
795 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
798 template <typename Q, typename Compare, typename Func>
799 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
801 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node)); } );
804 template <typename Q, typename Compare>
805 guarded_ptr extract_at( head_type& refHead, Q const& key, Compare cmp )
807 return base_class::extract_at( refHead, key, cmp );
810 template <typename Q, typename Func>
811 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
813 scoped_node_ptr pNode( alloc_node( key ));
815 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
816 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
818 if ( ret.first && ret.second )
824 template <typename Q, typename Compare>
825 bool find_at( head_type& refHead, Q const& key, Compare cmp )
827 return base_class::find_at( refHead, key, cmp );
830 template <typename Q, typename Compare, typename Func>
831 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
833 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
836 template <typename Q, typename Compare>
837 guarded_ptr get_at( head_type& refHead, Q const& key, Compare cmp )
839 return base_class::get_at( refHead, key, cmp );
845 }} // namespace cds::container
847 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H