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_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 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_set<node_type, value_type> > guarded_ptr;
159 static value_type& node_to_value( node_type& n )
163 static value_type const& node_to_value( node_type const& n )
168 template <typename Q>
169 static node_type * alloc_node( Q const& v )
171 return cxx_allocator().New( v );
174 template <typename... Args>
175 static node_type * alloc_node( Args&&... args )
177 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
180 static void free_node( node_type * pNode )
182 cxx_allocator().Delete( pNode );
185 struct node_disposer {
186 void operator()( node_type * pNode )
191 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
195 return base_class::m_pHead;
198 head_type const& head() const
200 return base_class::m_pHead;
206 template <bool IsConst>
207 class iterator_type: protected base_class::template iterator_type<IsConst>
209 typedef typename base_class::template iterator_type<IsConst> iterator_base;
211 iterator_type( head_type const& pNode )
212 : iterator_base( pNode )
215 friend class MichaelList;
218 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
219 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
224 iterator_type( iterator_type const& src )
225 : iterator_base( src )
228 value_ptr operator ->() const
230 typename iterator_base::value_ptr p = iterator_base::operator ->();
231 return p ? &(p->m_Value) : nullptr;
234 value_ref operator *() const
236 return (iterator_base::operator *()).m_Value;
240 iterator_type& operator ++()
242 iterator_base::operator ++();
247 bool operator ==(iterator_type<C> const& i ) const
249 return iterator_base::operator ==(i);
252 bool operator !=(iterator_type<C> const& i ) const
254 return iterator_base::operator !=(i);
260 ///@name Forward iterators (only for debugging purpose)
264 The forward iterator for Michael's list has some features:
265 - it has no post-increment operator
266 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
267 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
268 may be thrown if a limit of guard count per thread is exceeded.
269 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
270 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
271 deleting operations it is no guarantee that you iterate all item in the list.
272 Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread.
274 @warning Use this iterator on the concurrent container for debugging purpose only.
276 typedef iterator_type<false> iterator;
278 /// Const forward iterator
280 For iterator's features and requirements see \ref iterator
282 typedef iterator_type<true> const_iterator;
284 /// Returns a forward iterator addressing the first element in a list
286 For empty list \code begin() == end() \endcode
290 return iterator( head() );
293 /// Returns an iterator that addresses the location succeeding the last element in a list
295 Do not use the value returned by <tt>end</tt> function to access any item.
296 Internally, <tt>end</tt> returning value equals to \p nullptr.
298 The returned value can be used only to control reaching the end of the list.
299 For empty list \code begin() == end() \endcode
306 /// Returns a forward const iterator addressing the first element in a list
307 const_iterator begin() const
309 return const_iterator( head() );
312 /// Returns a forward const iterator addressing the first element in a list
313 const_iterator cbegin() const
315 return const_iterator( head() );
318 /// Returns an const iterator that addresses the location succeeding the last element in a list
319 const_iterator end() const
321 return const_iterator();
324 /// Returns an const iterator that addresses the location succeeding the last element in a list
325 const_iterator cend() const
327 return const_iterator();
332 /// Default constructor
334 Initialize empty list
340 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
341 explicit MichaelList( Stat& st )
357 The function creates a node with copy of \p val value
358 and then inserts the node created into the list.
360 The type \p Q should contain least the complete key of the node.
361 The object of \ref value_type should be constructible from \p val of type \p Q.
362 In trivial case, \p Q is equal to \ref value_type.
364 Returns \p true if inserting successful, \p false otherwise.
366 template <typename Q>
367 bool insert( Q const& val )
369 return insert_at( head(), val );
374 This function inserts new node with default-constructed value and then it calls
375 \p func functor with signature
376 \code void func( value_type& itemValue ) ;\endcode
378 The argument \p itemValue of user-defined functor \p func is the reference
379 to the list's item inserted. User-defined functor \p func should guarantee that during changing
380 item's value no any other changes could be made on this list's item by concurrent threads.
381 The user-defined functor is called only if inserting is success.
383 The type \p Q should contain the complete key of the node.
384 The object of \p value_type should be constructible from \p key of type \p Q.
386 The function allows to split creating of new item into two part:
387 - create item from \p key with initializing key-fields only;
388 - insert new item into the list;
389 - if inserting is successful, initialize non-key fields of item by calling \p func functor
391 The method can be useful if complete initialization of object of \p value_type is heavyweight and
392 it is preferable that the initialization should be completed only if inserting is successful.
394 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
396 template <typename Q, typename Func>
397 bool insert( Q const& key, Func func )
399 return insert_at( head(), key, func );
402 /// Updates data by \p key
404 The operation performs inserting or replacing the element with lock-free manner.
406 If the \p key not found in the list, then the new item created from \p key
407 will be inserted iff \p bAllowInsert is \p true.
408 Otherwise, if \p key is found, the functor \p func is called with item found.
410 The functor \p Func signature is:
413 void operator()( bool bNew, value_type& item, Q const& val );
418 - \p bNew - \p true if the item has been inserted, \p false otherwise
419 - \p item - item of the list
420 - \p val - argument \p key passed into the \p %update() function
422 The functor may change non-key fields of the \p item; however, \p func must guarantee
423 that during changing no any other modifications could be made on this item by concurrent threads.
425 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
426 \p second is true if new item has been added or \p false if the item with \p key
429 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
431 template <typename Q, typename Func>
432 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
434 return update_at( head(), key, func, bAllowInsert );
437 template <typename Q, typename Func>
438 CDS_DEPRECATED("ensure() is deprecated, use update()")
439 std::pair<bool, bool> ensure( Q const& key, Func func )
441 return update( key, func );
445 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
447 Returns \p true if inserting successful, \p false otherwise.
449 template <typename... Args>
450 bool emplace( Args&&... args )
452 return emplace_at( head(), std::forward<Args>(args)... );
455 /// Delete \p key from the list
456 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
457 Since the key of MichaelList's item type \p value_type is not explicitly specified,
458 template parameter \p Q sould contain the complete key to search in the list.
459 The list item comparator should be able to compare the type \p value_type
462 Return \p true if key is found and deleted, \p false otherwise
464 template <typename Q>
465 bool erase( Q const& key )
467 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
470 /// Deletes the item from the list using \p pred predicate for searching
472 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
473 but \p pred is used for key comparing.
474 \p Less functor has the interface like \p std::less.
475 \p pred must imply the same element order as the comparator used for building the list.
477 template <typename Q, typename Less>
478 bool erase_with( Q const& key, Less pred )
481 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
484 /// Deletes \p key from the list
485 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
486 The function searches an item with key \p key, calls \p f functor with item found
487 and deletes it. If \p key is not found, the functor is not called.
489 The functor \p Func interface:
492 void operator()(const value_type& val) { ... }
496 Since the key of MichaelList's item type \p value_type is not explicitly specified,
497 template parameter \p Q should contain the complete key to search in the list.
498 The list item comparator should be able to compare the type \p value_type of list item
501 Return \p true if key is found and deleted, \p false otherwise
503 template <typename Q, typename Func>
504 bool erase( Q const& key, Func f )
506 return erase_at( head(), key, intrusive_key_comparator(), f );
509 /// Deletes the item from the list using \p pred predicate for searching
511 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
512 but \p pred is used for key comparing.
513 \p Less functor has the interface like \p std::less.
514 \p pred must imply the same element order as the comparator used for building the list.
516 template <typename Q, typename Less, typename Func>
517 bool erase_with( Q const& key, Less pred, Func f )
520 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
523 /// Extracts the item from the list with specified \p key
524 /** \anchor cds_nonintrusive_MichaelList_hp_extract
525 The function searches an item with key equal to \p key,
526 unlinks it from the list, and returns it as \p guarded_ptr.
527 If \p key is not found the function returns an empty guarded pointer.
529 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
531 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
535 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
539 ord_list::guarded_ptr gp(theList.extract( 5 ));
544 // Destructor of gp releases internal HP guard and frees the item
548 template <typename Q>
549 guarded_ptr extract( Q const& key )
552 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
556 /// Extracts the item from the list with comparing functor \p pred
558 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(Q const&)"
559 but \p pred predicate is used for key comparing.
561 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
563 \p pred must imply the same element order as the comparator used for building the list.
565 template <typename Q, typename Less>
566 guarded_ptr extract_with( Q const& key, Less pred )
570 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
574 /// Checks whether the list contains \p key
576 The function searches the item with key equal to \p key
577 and returns \p true if it is found, and \p false otherwise.
579 template <typename Q>
580 bool contains( Q const& key )
582 return find_at( head(), key, intrusive_key_comparator() );
585 template <typename Q>
586 CDS_DEPRECATED("deprecated, use contains()")
587 bool find( Q const& key )
589 return contains( key );
593 /// Checks whether the list contains \p key using \p pred predicate for searching
595 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
596 \p Less functor has the interface like \p std::less.
597 \p pred must imply the same element order as the comparator used for building the list.
599 template <typename Q, typename Less>
600 bool contains( Q const& key, Less pred )
603 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
606 template <typename Q, typename Less>
607 CDS_DEPRECATED("deprecated, use contains()")
608 bool find_with( Q const& key, Less pred )
610 return contains( key, pred );
614 /// Finds \p key and perform an action with it
615 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
616 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
617 The interface of \p Func functor is:
620 void operator()( value_type& item, Q& key );
623 where \p item is the item found, \p key is the <tt>find</tt> function argument.
625 The functor may change non-key fields of \p item. Note that the function is only guarantee
626 that \p item cannot be deleted during functor is executing.
627 The function does not serialize simultaneous access to the list \p item. If such access is
628 possible you must provide your own synchronization schema to exclude unsafe item modifications.
630 The function returns \p true if \p key is found, \p false otherwise.
632 template <typename Q, typename Func>
633 bool find( Q& key, Func f )
635 return find_at( head(), key, intrusive_key_comparator(), f );
638 template <typename Q, typename Func>
639 bool find( Q const& key, Func f )
641 return find_at( head(), key, intrusive_key_comparator(), f );
645 /// Finds \p key using \p pred predicate for searching
647 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
648 but \p pred is used for key comparing.
649 \p Less functor has the interface like \p std::less.
650 \p pred must imply the same element order as the comparator used for building the list.
652 template <typename Q, typename Less, typename Func>
653 bool find_with( Q& key, Less pred, Func f )
656 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
659 template <typename Q, typename Less, typename Func>
660 bool find_with( Q const& key, Less pred, Func f )
663 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
667 /// Finds \p key and return the item found
668 /** \anchor cds_nonintrusive_MichaelList_hp_get
669 The function searches the item with key equal to \p key
670 and returns it as \p guarded_ptr.
671 If \p key is not found the function returns an empty guarded pointer.
673 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
677 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
681 ord_list::guarded_ptr gp(theList.get( 5 ));
686 // Destructor of guarded_ptr releases internal HP guard and frees the item
690 Note the compare functor specified for class \p Traits template parameter
691 should accept a parameter of type \p Q that can be not the same as \p value_type.
693 template <typename Q>
694 guarded_ptr get( Q const& key )
697 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
701 /// Finds \p key and return the item found
703 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
704 but \p pred is used for comparing the keys.
706 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
708 \p pred must imply the same element order as the comparator used for building the list.
710 template <typename Q, typename Less>
711 guarded_ptr get_with( Q const& key, Less pred )
715 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
719 /// Check if the list is empty
722 return base_class::empty();
725 /// Returns list's item count
727 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
728 this function always returns 0.
730 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
731 is empty. To check list emptyness use \p empty() method.
735 return base_class::size();
744 /// Returns const reference to internal statistics
745 stat const& statistics() const
747 return base_class::statistics();
752 bool insert_node( node_type * pNode )
754 return insert_node_at( head(), pNode );
757 bool insert_node_at( head_type& refHead, node_type * pNode )
760 scoped_node_ptr p(pNode);
761 if ( base_class::insert_at( refHead, *pNode )) {
769 template <typename Q>
770 bool insert_at( head_type& refHead, Q const& val )
772 return insert_node_at( refHead, alloc_node( val ));
775 template <typename Q, typename Func>
776 bool insert_at( head_type& refHead, Q const& key, Func f )
778 scoped_node_ptr pNode( alloc_node( key ));
780 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
787 template <typename... Args>
788 bool emplace_at( head_type& refHead, Args&&... args )
790 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
793 template <typename Q, typename Compare, typename Func>
794 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
796 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
799 template <typename Q, typename Compare>
800 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
802 return base_class::extract_at( refHead, guard, key, cmp );
805 template <typename Q, typename Func>
806 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
808 scoped_node_ptr pNode( alloc_node( key ));
810 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
811 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
813 if ( ret.first && ret.second )
819 template <typename Q, typename Compare>
820 bool find_at( head_type& refHead, Q const& key, Compare cmp )
822 return base_class::find_at( refHead, key, cmp );
825 template <typename Q, typename Compare, typename Func>
826 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
828 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
831 template <typename Q, typename Compare>
832 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
834 return base_class::get_at( refHead, guard, key, cmp );
840 }} // namespace cds::container
842 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H