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 (gc::HP, gc::HRC), 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) { ... }
450 The functor may be passed by reference with <tt>boost:ref</tt>
452 Since the key of MichaelList's item type \p value_type is not explicitly specified,
453 template parameter \p Q should contain the complete key to search in the list.
454 The list item comparator should be able to compare the type \p value_type of list item
457 Return \p true if key is found and deleted, \p false otherwise
459 template <typename Q, typename Func>
460 bool erase( Q const& key, Func f )
462 return erase_at( head(), key, intrusive_key_comparator(), f );
465 /// Deletes the item from the list using \p pred predicate for searching
467 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
468 but \p pred is used for key comparing.
469 \p Less functor has the interface like \p std::less.
470 \p pred must imply the same element order as the comparator used for building the list.
472 template <typename Q, typename Less, typename Func>
473 bool erase_with( Q const& key, Less pred, Func f )
475 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
478 /// Extracts the item from the list with specified \p key
479 /** \anchor cds_nonintrusive_MichaelList_hp_extract
480 The function searches an item with key equal to \p key,
481 unlinks it from the list, and returns it in \p dest parameter.
482 If the item with key equal to \p key is not found the function returns \p false.
484 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
486 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
490 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
494 ord_list::guarded_ptr gp;
495 theList.extract( gp, 5 );
499 // Destructor of gp releases internal HP guard and frees the item
503 template <typename Q>
504 bool extract( guarded_ptr& dest, Q const& key )
506 return extract_at( head(), dest.guard(), key, intrusive_key_comparator() );
509 /// Extracts the item from the list with comparing functor \p pred
511 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(guarded_ptr&, Q const&)"
512 but \p pred predicate is used for key comparing.
514 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
516 \p pred must imply the same element order as the comparator used for building the list.
518 template <typename Q, typename Less>
519 bool extract_with( guarded_ptr& dest, Q const& key, Less pred )
521 return extract_at( head(), dest.guard(), key, typename maker::template less_wrapper<Less>::type() );
525 /** \anchor cds_nonintrusive_MichaelList_hp_find_val
526 The function searches the item with key equal to \p key
527 and returns \p true if it is found, and \p false otherwise
529 template <typename Q>
530 bool find( Q const& key )
532 return find_at( head(), key, intrusive_key_comparator() );
535 /// Finds \p key using \p pred predicate for searching
537 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_val "find(Q const&)"
538 but \p pred is used for key comparing.
539 \p Less functor has the interface like \p std::less.
540 \p pred must imply the same element order as the comparator used for building the list.
542 template <typename Q, typename Less>
543 bool find_with( Q const& key, Less pred )
545 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
548 /// Finds \p key and perform an action with it
549 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
550 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
551 The interface of \p Func functor is:
554 void operator()( value_type& item, Q& key );
557 where \p item is the item found, \p key is the <tt>find</tt> function argument.
559 The functor may change non-key fields of \p item. Note that the function is only guarantee
560 that \p item cannot be deleted during functor is executing.
561 The function does not serialize simultaneous access to the list \p item. If such access is
562 possible you must provide your own synchronization schema to exclude unsafe item modifications.
564 The function returns \p true if \p key is found, \p false otherwise.
566 template <typename Q, typename Func>
567 bool find( Q& key, Func f )
569 return find_at( head(), key, intrusive_key_comparator(), f );
572 /// Finds \p key using \p pred predicate for searching
574 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
575 but \p pred is used for key comparing.
576 \p Less functor has the interface like \p std::less.
577 \p pred must imply the same element order as the comparator used for building the list.
579 template <typename Q, typename Less, typename Func>
580 bool find_with( Q& key, Less pred, Func f )
582 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
585 /// Finds \p key and return the item found
586 /** \anchor cds_nonintrusive_MichaelList_hp_get
587 The function searches the item with key equal to \p key
588 and assigns the item found to guarded pointer \p ptr.
589 The function returns \p true if \p key is found, and \p false otherwise.
590 If \p key is not found the \p ptr parameter is not changed.
592 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
596 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
600 ord_list::guarded_ptr gp;
601 if ( theList.get( gp, 5 )) {
605 // Destructor of guarded_ptr releases internal HP guard and frees the item
609 Note the compare functor specified for class \p Traits template parameter
610 should accept a parameter of type \p Q that can be not the same as \p value_type.
612 template <typename Q>
613 bool get( guarded_ptr& ptr, Q const& key )
615 return get_at( head(), ptr.guard(), key, intrusive_key_comparator() );
618 /// Finds \p key and return the item found
620 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( guarded_ptr& ptr, Q const&)"
621 but \p pred is used for comparing the keys.
623 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
625 \p pred must imply the same element order as the comparator used for building the list.
627 template <typename Q, typename Less>
628 bool get_with( guarded_ptr& ptr, Q const& key, Less pred )
630 return get_at( head(), ptr.guard(), key, typename maker::template less_wrapper<Less>::type() );
633 /// Check if the list is empty
636 return base_class::empty();
639 /// Returns list's item count
641 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
642 this function always returns 0.
644 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
645 is empty. To check list emptyness use \p empty() method.
649 return base_class::size();
660 bool insert_node_at( head_type& refHead, node_type * pNode )
663 scoped_node_ptr p(pNode);
664 if ( base_class::insert_at( refHead, *pNode )) {
672 template <typename Q>
673 bool insert_at( head_type& refHead, Q const& val )
675 return insert_node_at( refHead, alloc_node( val ));
678 template <typename Q, typename Func>
679 bool insert_at( head_type& refHead, Q const& key, Func f )
681 scoped_node_ptr pNode( alloc_node( key ));
683 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
690 template <typename... Args>
691 bool emplace_at( head_type& refHead, Args&&... args )
693 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
696 template <typename Q, typename Compare, typename Func>
697 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
699 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
702 template <typename Q, typename Compare>
703 bool extract_at( head_type& refHead, typename gc::Guard& dest, Q const& key, Compare cmp )
705 return base_class::extract_at( refHead, dest, key, cmp );
708 template <typename Q, typename Func>
709 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
711 scoped_node_ptr pNode( alloc_node( key ));
713 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
714 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
715 if ( ret.first && ret.second )
721 template <typename Q, typename Compare>
722 bool find_at( head_type& refHead, Q const& key, Compare cmp )
724 return base_class::find_at( refHead, key, cmp );
727 template <typename Q, typename Compare, typename Func>
728 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
730 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
733 template <typename Q, typename Compare>
734 bool get_at( head_type& refHead, typename gc::Guard& guard, Q const& key, Compare cmp )
736 return base_class::get_at( refHead, guard, key, cmp );
742 }} // namespace cds::container
744 #endif // #ifndef __CDS_CONTAINER_IMPL_MICHAEL_LIST_H