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
140 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
144 typedef typename base_class::value_type node_type;
145 typedef typename maker::cxx_allocator cxx_allocator;
146 typedef typename maker::node_deallocator node_deallocator;
147 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
149 typedef typename base_class::atomic_node_ptr head_type;
154 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
158 static value_type& node_to_value( node_type& n )
162 static value_type const& node_to_value( node_type const& n )
170 template <typename Q>
171 static node_type * alloc_node( Q const& v )
173 return cxx_allocator().New( v );
176 template <typename... Args>
177 static node_type * alloc_node( Args&&... args )
179 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
182 static void free_node( node_type * pNode )
184 cxx_allocator().Delete( pNode );
187 struct node_disposer {
188 void operator()( node_type * pNode )
193 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
197 return base_class::m_pHead;
200 head_type const& head() const
202 return base_class::m_pHead;
208 template <bool IsConst>
209 class iterator_type: protected base_class::template iterator_type<IsConst>
211 typedef typename base_class::template iterator_type<IsConst> iterator_base;
213 iterator_type( head_type const& pNode )
214 : iterator_base( pNode )
217 friend class MichaelList;
220 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
221 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
226 iterator_type( iterator_type const& src )
227 : iterator_base( src )
230 value_ptr operator ->() const
232 typename iterator_base::value_ptr p = iterator_base::operator ->();
233 return p ? &(p->m_Value) : nullptr;
236 value_ref operator *() const
238 return (iterator_base::operator *()).m_Value;
242 iterator_type& operator ++()
244 iterator_base::operator ++();
249 bool operator ==(iterator_type<C> const& i ) const
251 return iterator_base::operator ==(i);
254 bool operator !=(iterator_type<C> const& i ) const
256 return iterator_base::operator !=(i);
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.
273 @warning Use this iterator on the concurrent container for debugging purpose only.
275 typedef iterator_type<false> iterator;
277 /// Const forward iterator
279 For iterator's features and requirements see \ref iterator
281 typedef iterator_type<true> const_iterator;
283 ///@name Forward iterators (only for debugging purpose)
285 /// Returns a forward iterator addressing the first element in a list
287 For empty list \code begin() == end() \endcode
291 return iterator( head() );
294 /// Returns an iterator that addresses the location succeeding the last element in a list
296 Do not use the value returned by <tt>end</tt> function to access any item.
297 Internally, <tt>end</tt> returning value equals to \p nullptr.
299 The returned value can be used only to control reaching the end of the list.
300 For empty list \code begin() == end() \endcode
307 /// Returns a forward const iterator addressing the first element in a list
308 const_iterator begin() const
310 return const_iterator( head() );
313 /// Returns a forward const iterator addressing the first element in a list
314 const_iterator cbegin() const
316 return const_iterator( head() );
319 /// Returns an const iterator that addresses the location succeeding the last element in a list
320 const_iterator end() const
322 return const_iterator();
325 /// Returns an const iterator that addresses the location succeeding the last element in a list
326 const_iterator cend() const
328 return const_iterator();
333 /// Default constructor
335 Initialize empty list
351 The function creates a node with copy of \p val value
352 and then inserts the node created into the list.
354 The type \p Q should contain least the complete key of the node.
355 The object of \ref value_type should be constructible from \p val of type \p Q.
356 In trivial case, \p Q is equal to \ref value_type.
358 Returns \p true if inserting successful, \p false otherwise.
360 template <typename Q>
361 bool insert( Q const& val )
363 return insert_at( head(), val );
368 This function inserts new node with default-constructed value and then it calls
369 \p func functor with signature
370 \code void func( value_type& itemValue ) ;\endcode
372 The argument \p itemValue of user-defined functor \p func is the reference
373 to the list's item inserted. User-defined functor \p func should guarantee that during changing
374 item's value no any other changes could be made on this list's item by concurrent threads.
375 The user-defined functor is called only if inserting is success.
377 The type \p Q should contain the complete key of the node.
378 The object of \p value_type should be constructible from \p key of type \p Q.
380 The function allows to split creating of new item into two part:
381 - create item from \p key with initializing key-fields only;
382 - insert new item into the list;
383 - if inserting is successful, initialize non-key fields of item by calling \p func functor
385 The method can be useful if complete initialization of object of \p value_type is heavyweight and
386 it is preferable that the initialization should be completed only if inserting is successful.
388 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
390 template <typename Q, typename Func>
391 bool insert( Q const& key, Func func )
393 return insert_at( head(), key, func );
396 /// Updates data by \p key
398 The operation performs inserting or replacing the element with lock-free manner.
400 If the \p key not found in the list, then the new item created from \p key
401 will be inserted iff \p bAllowInsert is \p true.
402 Otherwise, if \p key is found, the functor \p func is called with item found.
404 The functor \p Func signature is:
407 void operator()( bool bNew, value_type& item, Q const& val );
412 - \p bNew - \p true if the item has been inserted, \p false otherwise
413 - \p item - item of the list
414 - \p val - argument \p key passed into the \p %update() function
416 The functor may change non-key fields of the \p item; however, \p func must guarantee
417 that during changing no any other modifications could be made on this item by concurrent threads.
419 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
420 \p second is true if new item has been added or \p false if the item with \p key
423 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
425 template <typename Q, typename Func>
426 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
428 return update_at( head(), key, func, bAllowInsert );
431 template <typename Q, typename Func>
432 CDS_DEPRECATED("ensure() is deprecated, use update()")
433 std::pair<bool, bool> ensure( Q const& key, Func func )
435 return update( key, func );
439 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
441 Returns \p true if inserting successful, \p false otherwise.
443 template <typename... Args>
444 bool emplace( Args&&... args )
446 return emplace_at( head(), std::forward<Args>(args)... );
449 /// Delete \p key from the list
450 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
451 Since the key of MichaelList's item type \p value_type is not explicitly specified,
452 template parameter \p Q sould contain the complete key to search in the list.
453 The list item comparator should be able to compare the type \p value_type
456 Return \p true if key is found and deleted, \p false otherwise
458 template <typename Q>
459 bool erase( Q const& key )
461 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
464 /// Deletes the item from the list using \p pred predicate for searching
466 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
467 but \p pred is used for key comparing.
468 \p Less functor has the interface like \p std::less.
469 \p pred must imply the same element order as the comparator used for building the list.
471 template <typename Q, typename Less>
472 bool erase_with( Q const& key, Less pred )
475 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
478 /// Deletes \p key from the list
479 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
480 The function searches an item with key \p key, calls \p f functor with item found
481 and deletes it. If \p key is not found, the functor is not called.
483 The functor \p Func interface:
486 void operator()(const value_type& val) { ... }
490 Since the key of MichaelList's item type \p value_type is not explicitly specified,
491 template parameter \p Q should contain the complete key to search in the list.
492 The list item comparator should be able to compare the type \p value_type of list item
495 Return \p true if key is found and deleted, \p false otherwise
497 template <typename Q, typename Func>
498 bool erase( Q const& key, Func f )
500 return erase_at( head(), key, intrusive_key_comparator(), f );
503 /// Deletes the item from the list using \p pred predicate for searching
505 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
506 but \p pred is used for key comparing.
507 \p Less functor has the interface like \p std::less.
508 \p pred must imply the same element order as the comparator used for building the list.
510 template <typename Q, typename Less, typename Func>
511 bool erase_with( Q const& key, Less pred, Func f )
514 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
517 /// Extracts the item from the list with specified \p key
518 /** \anchor cds_nonintrusive_MichaelList_hp_extract
519 The function searches an item with key equal to \p key,
520 unlinks it from the list, and returns it as \p guarded_ptr.
521 If \p key is not found the function returns an empty guarded pointer.
523 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
525 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
529 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
533 ord_list::guarded_ptr gp(theList.extract( 5 ));
538 // Destructor of gp releases internal HP guard and frees the item
542 template <typename Q>
543 guarded_ptr extract( Q const& key )
546 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
550 /// Extracts the item from the list with comparing functor \p pred
552 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(Q const&)"
553 but \p pred predicate is used for key comparing.
555 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
557 \p pred must imply the same element order as the comparator used for building the list.
559 template <typename Q, typename Less>
560 guarded_ptr extract_with( Q const& key, Less pred )
564 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
568 /// Checks whether the list contains \p key
570 The function searches the item with key equal to \p key
571 and returns \p true if it is found, and \p false otherwise.
573 template <typename Q>
574 bool contains( Q const& key )
576 return find_at( head(), key, intrusive_key_comparator() );
579 template <typename Q>
580 CDS_DEPRECATED("deprecated, use contains()")
581 bool find( Q const& key )
583 return contains( key );
587 /// Checks whether the list contains \p key using \p pred predicate for searching
589 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
590 \p Less functor has the interface like \p std::less.
591 \p pred must imply the same element order as the comparator used for building the list.
593 template <typename Q, typename Less>
594 bool contains( Q const& key, Less pred )
597 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
600 template <typename Q, typename Less>
601 CDS_DEPRECATED("deprecated, use contains()")
602 bool find_with( Q const& key, Less pred )
604 return contains( key, pred );
608 /// Finds \p key and perform an action with it
609 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
610 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
611 The interface of \p Func functor is:
614 void operator()( value_type& item, Q& key );
617 where \p item is the item found, \p key is the <tt>find</tt> function argument.
619 The functor may change non-key fields of \p item. Note that the function is only guarantee
620 that \p item cannot be deleted during functor is executing.
621 The function does not serialize simultaneous access to the list \p item. If such access is
622 possible you must provide your own synchronization schema to exclude unsafe item modifications.
624 The function returns \p true if \p key is found, \p false otherwise.
626 template <typename Q, typename Func>
627 bool find( Q& key, Func f )
629 return find_at( head(), key, intrusive_key_comparator(), f );
632 template <typename Q, typename Func>
633 bool find( Q const& key, Func f )
635 return find_at( head(), key, intrusive_key_comparator(), f );
639 /// Finds \p key using \p pred predicate for searching
641 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
642 but \p pred is used for key comparing.
643 \p Less functor has the interface like \p std::less.
644 \p pred must imply the same element order as the comparator used for building the list.
646 template <typename Q, typename Less, typename Func>
647 bool find_with( Q& key, Less pred, Func f )
650 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
653 template <typename Q, typename Less, typename Func>
654 bool find_with( Q const& key, Less pred, Func f )
657 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
661 /// Finds \p key and return the item found
662 /** \anchor cds_nonintrusive_MichaelList_hp_get
663 The function searches the item with key equal to \p key
664 and returns it as \p guarded_ptr.
665 If \p key is not found the function returns an empty guarded pointer.
667 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
671 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
675 ord_list::guarded_ptr gp(theList.get( 5 ));
680 // Destructor of guarded_ptr releases internal HP guard and frees the item
684 Note the compare functor specified for class \p Traits template parameter
685 should accept a parameter of type \p Q that can be not the same as \p value_type.
687 template <typename Q>
688 guarded_ptr get( Q const& key )
691 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
695 /// Finds \p key and return the item found
697 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
698 but \p pred is used for comparing the keys.
700 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
702 \p pred must imply the same element order as the comparator used for building the list.
704 template <typename Q, typename Less>
705 guarded_ptr get_with( Q const& key, Less pred )
709 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
713 /// Check if the list is empty
716 return base_class::empty();
719 /// Returns list's item count
721 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
722 this function always returns 0.
724 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
725 is empty. To check list emptyness use \p empty() method.
729 return base_class::size();
740 bool insert_node_at( head_type& refHead, node_type * pNode )
743 scoped_node_ptr p(pNode);
744 if ( base_class::insert_at( refHead, *pNode )) {
752 template <typename Q>
753 bool insert_at( head_type& refHead, Q const& val )
755 return insert_node_at( refHead, alloc_node( val ));
758 template <typename Q, typename Func>
759 bool insert_at( head_type& refHead, Q const& key, Func f )
761 scoped_node_ptr pNode( alloc_node( key ));
763 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
770 template <typename... Args>
771 bool emplace_at( head_type& refHead, Args&&... args )
773 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
776 template <typename Q, typename Compare, typename Func>
777 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
779 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
782 template <typename Q, typename Compare>
783 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
785 return base_class::extract_at( refHead, guard, key, cmp );
788 template <typename Q, typename Func>
789 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
791 scoped_node_ptr pNode( alloc_node( key ));
793 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
794 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
796 if ( ret.first && ret.second )
802 template <typename Q, typename Compare>
803 bool find_at( head_type& refHead, Q const& key, Compare cmp )
805 return base_class::find_at( refHead, key, cmp );
808 template <typename Q, typename Compare, typename Func>
809 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
811 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
814 template <typename Q, typename Compare>
815 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
817 return base_class::get_at( refHead, guard, key, cmp );
823 }} // namespace cds::container
825 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H