3 #ifndef __CDS_CONTAINER_IMPL_MICHAEL_LIST_H
4 #define __CDS_CONTAINER_IMPL_MICHAEL_LIST_H
7 #include <cds/container/details/guarded_ptr_cast.h>
9 namespace cds { namespace container {
11 /// Michael's ordered list
12 /** @ingroup cds_nonintrusive_list
13 \anchor cds_nonintrusive_MichaelList_gc
15 Usually, ordered single-linked list is used as a building block for the hash table implementation.
16 The complexity of searching is <tt>O(N)</tt>, where \p N is the item count in the list, not in the
20 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
22 This class is non-intrusive version of cds::intrusive::MichaelList class
25 - \p GC - garbage collector used
26 - \p T - type stored in the list. The type must be default- and copy-constructible.
27 - \p Traits - type traits, default is \p michael_list::traits
29 Unlike standard container, this implementation does not divide type \p T into key and value part and
30 may be used as a main building block for hash set algorithms.
31 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
32 or <tt>Traits::less</tt> predicate
34 MichaelKVList is a key-value version of Michael's non-intrusive list that is closer to the C++ std library approach.
36 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
37 argument. For example, the following traits-based declaration of gc::HP Michael's list
39 #include <cds/container/michael_list_hp.h>
40 // Declare comparator for the item
42 int operator ()( int i1, int i2 )
49 struct my_traits: public cds::container::michael_list::traits
51 typedef my_compare compare;
54 // Declare traits-based list
55 typedef cds::container::MichaelList< cds::gc::HP, int, my_traits > traits_based_list;
58 is equivalent for the following option-based list
60 #include <cds/container/michael_list_hp.h>
62 // my_compare is the same
64 // Declare option-based list
65 typedef cds::container::MichaelList< cds::gc::HP, int,
66 typename cds::container::michael_list::make_traits<
67 cds::container::opt::compare< my_compare > // item comparator option
73 There are different specializations of this template for each garbage collecting schema used.
74 You should include appropriate .h-file depending on GC you are using:
75 - for gc::HP: \code #include <cds/container/michael_list_hp.h> \endcode
76 - for gc::DHP: \code #include <cds/container/michael_list_dhp.h> \endcode
77 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_list_rcu.h> \endcode
78 - for gc::nogc: \code #include <cds/container/michael_list_nogc.h> \endcode
83 #ifdef CDS_DOXYGEN_INVOKED
84 typename Traits = michael_list::traits
90 #ifdef CDS_DOXYGEN_INVOKED
91 protected intrusive::MichaelList< GC, T, Traits >
93 protected details::make_michael_list< GC, T, Traits >::type
97 typedef details::make_michael_list< GC, T, Traits > maker;
98 typedef typename maker::type base_class;
102 typedef T value_type; ///< Type of value stored in the list
103 typedef Traits traits; ///< List traits
105 typedef typename base_class::gc gc; ///< Garbage collector used
106 typedef typename base_class::back_off back_off; ///< Back-off strategy used
107 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
108 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
109 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
110 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See \p cds::opt::memory_model option
114 typedef typename base_class::value_type node_type;
115 typedef typename maker::cxx_allocator cxx_allocator;
116 typedef typename maker::node_deallocator node_deallocator;
117 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
119 typedef typename base_class::atomic_node_ptr head_type;
124 typedef cds::gc::guarded_ptr< gc, node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
128 static value_type& node_to_value( node_type& n )
132 static value_type const& node_to_value( node_type const& n )
140 template <typename Q>
141 static node_type * alloc_node( Q const& v )
143 return cxx_allocator().New( v );
146 template <typename... Args>
147 static node_type * alloc_node( Args&&... args )
149 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
152 static void free_node( node_type * pNode )
154 cxx_allocator().Delete( pNode );
157 struct node_disposer {
158 void operator()( node_type * pNode )
163 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
167 return base_class::m_pHead;
170 head_type const& head() const
172 return base_class::m_pHead;
178 template <bool IsConst>
179 class iterator_type: protected base_class::template iterator_type<IsConst>
181 typedef typename base_class::template iterator_type<IsConst> iterator_base;
183 iterator_type( head_type const& pNode )
184 : iterator_base( pNode )
187 friend class MichaelList;
190 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
191 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
196 iterator_type( iterator_type const& src )
197 : iterator_base( src )
200 value_ptr operator ->() const
202 typename iterator_base::value_ptr p = iterator_base::operator ->();
203 return p ? &(p->m_Value) : nullptr;
206 value_ref operator *() const
208 return (iterator_base::operator *()).m_Value;
212 iterator_type& operator ++()
214 iterator_base::operator ++();
219 bool operator ==(iterator_type<C> const& i ) const
221 return iterator_base::operator ==(i);
224 bool operator !=(iterator_type<C> const& i ) const
226 return iterator_base::operator !=(i);
234 The forward iterator for Michael's list has some features:
235 - it has no post-increment operator
236 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
237 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
238 may be thrown if a limit of guard count per thread is exceeded.
239 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
240 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
241 deleting operations it is no guarantee that you iterate all item in the list.
243 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
244 for debug purpose only.
246 typedef iterator_type<false> iterator;
248 /// Const forward iterator
250 For iterator's features and requirements see \ref iterator
252 typedef iterator_type<true> const_iterator;
254 /// Returns a forward iterator addressing the first element in a list
256 For empty list \code begin() == end() \endcode
260 return iterator( head() );
263 /// Returns an iterator that addresses the location succeeding the last element in a list
265 Do not use the value returned by <tt>end</tt> function to access any item.
266 Internally, <tt>end</tt> returning value equals to \p nullptr.
268 The returned value can be used only to control reaching the end of the list.
269 For empty list \code begin() == end() \endcode
276 /// Returns a forward const iterator addressing the first element in a list
278 const_iterator begin() const
280 return const_iterator( head() );
282 const_iterator cbegin() const
284 return const_iterator( head() );
288 /// Returns an const iterator that addresses the location succeeding the last element in a list
290 const_iterator end() const
292 return const_iterator();
294 const_iterator cend() const
296 return const_iterator();
301 /// Default constructor
303 Initialize empty list
319 The function creates a node with copy of \p val value
320 and then inserts the node created into the list.
322 The type \p Q should contain least the complete key of the node.
323 The object of \ref value_type should be constructible from \p val of type \p Q.
324 In trivial case, \p Q is equal to \ref value_type.
326 Returns \p true if inserting successful, \p false otherwise.
328 template <typename Q>
329 bool insert( Q const& val )
331 return insert_at( head(), val );
336 This function inserts new node with default-constructed value and then it calls
337 \p func functor with signature
338 \code void func( value_type& itemValue ) ;\endcode
340 The argument \p itemValue of user-defined functor \p func is the reference
341 to the list's item inserted. User-defined functor \p func should guarantee that during changing
342 item's value no any other changes could be made on this list's item by concurrent threads.
343 The user-defined functor is called only if inserting is success.
345 The type \p Q should contain the complete key of the node.
346 The object of \p value_type should be constructible from \p key of type \p Q.
348 The function allows to split creating of new item into two part:
349 - create item from \p key with initializing key-fields only;
350 - insert new item into the list;
351 - if inserting is successful, initialize non-key fields of item by calling \p func functor
353 The method can be useful if complete initialization of object of \p value_type is heavyweight and
354 it is preferable that the initialization should be completed only if inserting is successful.
356 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
358 template <typename Q, typename Func>
359 bool insert( Q const& key, Func func )
361 return insert_at( head(), key, func );
364 /// Ensures that the \p key exists in the list
366 The operation performs inserting or changing data with lock-free manner.
368 If the \p key not found in the list, then the new item created from \p key
369 is inserted into the list. Otherwise, the functor \p func is called with the item found.
370 The functor \p Func should be a function with signature:
372 void func( bool bNew, value_type& item, const Q& val );
377 void operator()( bool bNew, value_type& item, const Q& val );
382 - \p bNew - \p true if the item has been inserted, \p false otherwise
383 - \p item - item of the list
384 - \p val - argument \p key passed into the \p ensure function
386 The functor may change non-key fields of the \p item; however, \p func must guarantee
387 that during changing no any other modifications could be made on this item by concurrent threads.
389 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
390 \p second is true if new item has been added or \p false if the item with \p key
391 already is in the list.
393 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
395 template <typename Q, typename Func>
396 std::pair<bool, bool> ensure( Q const& key, Func func )
398 return ensure_at( head(), key, func );
401 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
403 Returns \p true if inserting successful, \p false otherwise.
405 template <typename... Args>
406 bool emplace( Args&&... args )
408 return emplace_at( head(), std::forward<Args>(args)... );
411 /// Delete \p key from the list
412 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
413 Since the key of MichaelList's item type \p value_type is not explicitly specified,
414 template parameter \p Q sould contain the complete key to search in the list.
415 The list item comparator should be able to compare the type \p value_type
418 Return \p true if key is found and deleted, \p false otherwise
420 template <typename Q>
421 bool erase( Q const& key )
423 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
426 /// Deletes the item from the list using \p pred predicate for searching
428 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
429 but \p pred is used for key comparing.
430 \p Less functor has the interface like \p std::less.
431 \p pred must imply the same element order as the comparator used for building the list.
433 template <typename Q, typename Less>
434 bool erase_with( Q const& key, Less pred )
436 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
439 /// Deletes \p key from the list
440 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
441 The function searches an item with key \p key, calls \p f functor with item found
442 and deletes it. If \p key is not found, the functor is not called.
444 The functor \p Func interface:
447 void operator()(const value_type& val) { ... }
451 Since the key of MichaelList's item type \p value_type is not explicitly specified,
452 template parameter \p Q should contain the complete key to search in the list.
453 The list item comparator should be able to compare the type \p value_type of list item
456 Return \p true if key is found and deleted, \p false otherwise
458 template <typename Q, typename Func>
459 bool erase( Q const& key, Func f )
461 return erase_at( head(), key, intrusive_key_comparator(), f );
464 /// Deletes the item from the list using \p pred predicate for searching
466 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
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, typename Func>
472 bool erase_with( Q const& key, Less pred, Func f )
474 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
477 /// Extracts the item from the list with specified \p key
478 /** \anchor cds_nonintrusive_MichaelList_hp_extract
479 The function searches an item with key equal to \p key,
480 unlinks it from the list, and returns it in \p dest parameter.
481 If the item with key equal to \p key is not found the function returns \p false.
483 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
485 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
489 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
493 ord_list::guarded_ptr gp;
494 theList.extract( gp, 5 );
498 // Destructor of gp releases internal HP guard and frees the item
502 template <typename Q>
503 bool extract( guarded_ptr& dest, Q const& key )
505 return extract_at( head(), dest.guard(), key, intrusive_key_comparator() );
508 /// Extracts the item from the list with comparing functor \p pred
510 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(guarded_ptr&, Q const&)"
511 but \p pred predicate is used for key comparing.
513 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
515 \p pred must imply the same element order as the comparator used for building the list.
517 template <typename Q, typename Less>
518 bool extract_with( guarded_ptr& dest, Q const& key, Less pred )
520 return extract_at( head(), dest.guard(), key, typename maker::template less_wrapper<Less>::type() );
524 /** \anchor cds_nonintrusive_MichaelList_hp_find_val
525 The function searches the item with key equal to \p key
526 and returns \p true if it is found, and \p false otherwise
528 template <typename Q>
529 bool find( Q const& key )
531 return find_at( head(), key, intrusive_key_comparator() );
534 /// Finds \p key using \p pred predicate for searching
536 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_val "find(Q const&)"
537 but \p pred is used for key comparing.
538 \p Less functor has the interface like \p std::less.
539 \p pred must imply the same element order as the comparator used for building the list.
541 template <typename Q, typename Less>
542 bool find_with( Q const& key, Less pred )
544 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
547 /// Finds \p key and perform an action with it
548 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
549 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
550 The interface of \p Func functor is:
553 void operator()( value_type& item, Q& key );
556 where \p item is the item found, \p key is the <tt>find</tt> function argument.
558 The functor may change non-key fields of \p item. Note that the function is only guarantee
559 that \p item cannot be deleted during functor is executing.
560 The function does not serialize simultaneous access to the list \p item. If such access is
561 possible you must provide your own synchronization schema to exclude unsafe item modifications.
563 The function returns \p true if \p key is found, \p false otherwise.
565 template <typename Q, typename Func>
566 bool find( Q& key, Func f )
568 return find_at( head(), key, intrusive_key_comparator(), f );
571 template <typename Q, typename Func>
572 bool find( Q const& key, Func f )
574 return find_at( head(), key, intrusive_key_comparator(), f );
578 /// Finds \p key using \p pred predicate for searching
580 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
581 but \p pred is used for key comparing.
582 \p Less functor has the interface like \p std::less.
583 \p pred must imply the same element order as the comparator used for building the list.
585 template <typename Q, typename Less, typename Func>
586 bool find_with( Q& key, Less pred, Func f )
588 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
591 template <typename Q, typename Less, typename Func>
592 bool find_with( Q const& key, Less pred, Func f )
594 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
598 /// Finds \p key and return the item found
599 /** \anchor cds_nonintrusive_MichaelList_hp_get
600 The function searches the item with key equal to \p key
601 and assigns the item found to guarded pointer \p ptr.
602 The function returns \p true if \p key is found, and \p false otherwise.
603 If \p key is not found the \p ptr parameter is not changed.
605 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
609 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
613 ord_list::guarded_ptr gp;
614 if ( theList.get( gp, 5 )) {
618 // Destructor of guarded_ptr releases internal HP guard and frees the item
622 Note the compare functor specified for class \p Traits template parameter
623 should accept a parameter of type \p Q that can be not the same as \p value_type.
625 template <typename Q>
626 bool get( guarded_ptr& ptr, Q const& key )
628 return get_at( head(), ptr.guard(), key, intrusive_key_comparator() );
631 /// Finds \p key and return the item found
633 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( guarded_ptr& ptr, Q const&)"
634 but \p pred is used for comparing the keys.
636 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
638 \p pred must imply the same element order as the comparator used for building the list.
640 template <typename Q, typename Less>
641 bool get_with( guarded_ptr& ptr, Q const& key, Less pred )
643 return get_at( head(), ptr.guard(), key, typename maker::template less_wrapper<Less>::type() );
646 /// Check if the list is empty
649 return base_class::empty();
652 /// Returns list's item count
654 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
655 this function always returns 0.
657 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
658 is empty. To check list emptyness use \p empty() method.
662 return base_class::size();
673 bool insert_node_at( head_type& refHead, node_type * pNode )
676 scoped_node_ptr p(pNode);
677 if ( base_class::insert_at( refHead, *pNode )) {
685 template <typename Q>
686 bool insert_at( head_type& refHead, Q const& val )
688 return insert_node_at( refHead, alloc_node( val ));
691 template <typename Q, typename Func>
692 bool insert_at( head_type& refHead, Q const& key, Func f )
694 scoped_node_ptr pNode( alloc_node( key ));
696 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
703 template <typename... Args>
704 bool emplace_at( head_type& refHead, Args&&... args )
706 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
709 template <typename Q, typename Compare, typename Func>
710 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
712 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
715 template <typename Q, typename Compare>
716 bool extract_at( head_type& refHead, typename gc::Guard& dest, Q const& key, Compare cmp )
718 return base_class::extract_at( refHead, dest, key, cmp );
721 template <typename Q, typename Func>
722 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
724 scoped_node_ptr pNode( alloc_node( key ));
726 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
727 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
728 if ( ret.first && ret.second )
734 template <typename Q, typename Compare>
735 bool find_at( head_type& refHead, Q const& key, Compare cmp )
737 return base_class::find_at( refHead, key, cmp );
740 template <typename Q, typename Compare, typename Func>
741 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
743 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
746 template <typename Q, typename Compare>
747 bool get_at( head_type& refHead, typename gc::Guard& guard, Q const& key, Compare cmp )
749 return base_class::get_at( refHead, guard, key, cmp );
755 }} // namespace cds::container
757 #endif // #ifndef __CDS_CONTAINER_IMPL_MICHAEL_LIST_H