3 #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
4 #define CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
7 #include <cds/container/details/michael_list_base.h>
8 #include <cds/intrusive/michael_list_rcu.h>
9 #include <cds/container/details/make_michael_list.h>
10 #include <cds/details/binary_functor_wrapper.h>
12 namespace cds { namespace container {
14 /// Michael's ordered list (template specialization for \ref cds_urcu_desc "RCU")
15 /** @ingroup cds_nonintrusive_list
16 \anchor cds_nonintrusive_MichaelList_rcu
18 Usually, ordered single-linked list is used as a building block for the hash table implementation.
19 The complexity of searching is <tt>O(N)</tt>.
22 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
24 This class is non-intrusive version of \ref cds_intrusive_MichaelList_rcu "cds::intrusive::MichaelList" RCU specialization.
27 - \p RCU - one of \ref cds_urcu_gc "RCU type"
28 - \p T - type stored in the list. The type must be default- and copy-constructible.
29 - \p Traits - type traits, default is michael_list::traits
31 The implementation does not divide type \p T into key and value part and
32 may be used as a main building block for hash set containers.
33 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
34 or <tt>Traits::less</tt> predicate.
36 \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" is a key-value version of Michael's
37 non-intrusive list that is closer to the C++ std library approach.
39 @note Before including <tt><cds/container/michael_list_rcu.h></tt> you should include appropriate RCU header file,
40 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
42 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
43 argument. For example, the following traits-based declaration of Michael's list
46 #include <cds/urcu/general_buffered.h>
47 #include <cds/container/michael_list_rcu.h>
48 // Declare comparator for the item
50 int operator ()( int i1, int i2 )
57 struct my_traits: public cds::container::michael_list::traits
59 typedef my_compare compare;
62 // Declare traits-based list
63 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, my_traits > traits_based_list;
66 is equivalent for the following option-based list
68 #include <cds/urcu/general_buffered.h>
69 #include <cds/container/michael_list_rcu.h>
71 // my_compare is the same
73 // Declare option-based list
74 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int,
75 typename cds::container::michael_list::make_traits<
76 cds::container::opt::compare< my_compare > // item comparator option
81 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
82 - opt::compare - key comparison functor. No default functor is provided.
83 If the option is not specified, the opt::less is used.
84 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
85 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
86 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
87 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
88 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
89 or opt::v::sequential_consistent (sequentially consisnent memory model).
90 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
95 #ifdef CDS_DOXYGEN_INVOKED
96 typename Traits = michael_list::traits
101 class MichaelList< cds::urcu::gc<RCU>, T, Traits > :
102 #ifdef CDS_DOXYGEN_INVOKED
103 protected intrusive::MichaelList< cds::urcu::gc<RCU>, T, Traits >
105 protected details::make_michael_list< cds::urcu::gc<RCU>, T, Traits >::type
109 typedef details::make_michael_list< cds::urcu::gc<RCU>, T, Traits > maker;
110 typedef typename maker::type base_class;
114 typedef cds::urcu::gc<RCU> gc; ///< RCU
115 typedef T value_type; ///< Type of value stored in the list
116 typedef Traits traits; ///< List traits
118 typedef typename base_class::back_off back_off; ///< Back-off strategy used
119 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
120 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
121 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
122 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
123 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
125 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
126 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
130 typedef typename base_class::value_type node_type;
131 typedef typename maker::cxx_allocator cxx_allocator;
132 typedef typename maker::node_deallocator node_deallocator;
133 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
135 typedef typename base_class::atomic_node_ptr head_type;
139 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
142 struct raw_ptr_converter
144 value_type * operator()( node_type * p ) const
146 return p ? &p->m_Value : nullptr;
149 value_type& operator()( node_type& n ) const
154 value_type const& operator()( node_type const& n ) const
161 /// Result of \p get(), \p get_with() functions - pointer to the node found
162 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
166 static value_type& node_to_value( node_type& n )
170 static value_type const& node_to_value( node_type const& n )
178 template <typename Q>
179 static node_type * alloc_node( Q const& v )
181 return cxx_allocator().New( v );
184 template <typename... Args>
185 static node_type * alloc_node( Args&&... args )
187 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
190 static void free_node( node_type * pNode )
192 cxx_allocator().Delete( pNode );
195 struct node_disposer {
196 void operator()( node_type * pNode )
201 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
205 return base_class::m_pHead;
208 head_type& head() const
210 return const_cast<head_type&>( base_class::m_pHead );
216 template <bool IsConst>
217 class iterator_type: protected base_class::template iterator_type<IsConst>
219 typedef typename base_class::template iterator_type<IsConst> iterator_base;
221 iterator_type( head_type const& pNode )
222 : iterator_base( pNode )
225 friend class MichaelList;
228 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
229 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
234 iterator_type( iterator_type const& src )
235 : iterator_base( src )
238 value_ptr operator ->() const
240 typename iterator_base::value_ptr p = iterator_base::operator ->();
241 return p ? &(p->m_Value) : nullptr;
244 value_ref operator *() const
246 return (iterator_base::operator *()).m_Value;
250 iterator_type& operator ++()
252 iterator_base::operator ++();
257 bool operator ==(iterator_type<C> const& i ) const
259 return iterator_base::operator ==(i);
262 bool operator !=(iterator_type<C> const& i ) const
264 return iterator_base::operator !=(i);
271 typedef iterator_type<false> iterator;
273 /// Const forward iterator
274 typedef iterator_type<true> const_iterator;
276 /// Returns a forward iterator addressing the first element in a list
278 For empty list \code begin() == end() \endcode
282 return iterator( head() );
285 /// Returns an iterator that addresses the location succeeding the last element in a list
287 Do not use the value returned by <tt>end</tt> function to access any item.
288 Internally, <tt>end</tt> returning value equals to \p nullptr.
290 The returned value can be used only to control reaching the end of the list.
291 For empty list \code begin() == end() \endcode
298 /// Returns a forward const iterator addressing the first element in a list
300 const_iterator begin() const
302 return const_iterator( head() );
304 const_iterator cbegin() const
306 return const_iterator( head() );
310 /// Returns an const iterator that addresses the location succeeding the last element in a list
312 const_iterator end() const
314 return const_iterator();
316 const_iterator cend() const
318 return const_iterator();
323 /// Default constructor
325 Initialize empty list
341 The function creates a node with copy of \p val value
342 and then inserts the node created into the list.
344 The type \p Q should contain as minimum the complete key of the node.
345 The object of \ref value_type should be constructible from \p val of type \p Q.
346 In trivial case, \p Q is equal to \ref value_type.
348 The function makes RCU lock internally.
350 Returns \p true if inserting successful, \p false otherwise.
352 template <typename Q>
353 bool insert( Q const& val )
355 return insert_at( head(), val );
360 This function inserts new node with default-constructed value and then it calls
361 \p func functor with signature
362 \code void func( value_type& itemValue ) ;\endcode
364 The argument \p itemValue of user-defined functor \p func is the reference
365 to the list's item inserted. User-defined functor \p func should guarantee that during changing
366 item's value no any other changes could be made on this list's item by concurrent threads.
368 The type \p Q should contain the complete key of the node.
369 The object of \ref value_type should be constructible from \p key of type \p Q.
371 The function allows to split creating of new item into two part:
372 - create item from \p key with initializing key-fields only;
373 - insert new item into the list;
374 - if inserting is successful, initialize non-key fields of item by calling \p f functor
376 This can be useful if complete initialization of object of \p value_type is heavyweight and
377 it is preferable that the initialization should be completed only if inserting is successful.
379 The function makes RCU lock internally.
381 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
383 template <typename Q, typename Func>
384 bool insert( Q const& key, Func func )
386 return insert_at( head(), key, func );
389 /// Ensures that the \p key exists in the list
391 The operation performs inserting or changing data with lock-free manner.
393 If the \p key not found in the list, then the new item created from \p key
394 is inserted into the list. Otherwise, the functor \p func is called with the item found.
395 The functor \p Func should be a function with signature:
397 void func( bool bNew, value_type& item, const Q& val );
402 void operator()( bool bNew, value_type& item, const Q& val );
407 - \p bNew - \p true if the item has been inserted, \p false otherwise
408 - \p item - item of the list
409 - \p val - argument \p key passed into the \p ensure function
411 The functor may change non-key fields of the \p item; however, \p func must guarantee
412 that during changing no any other modifications could be made on this item by concurrent threads.
414 The function makes RCU lock internally.
416 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
417 \p second is true if new item has been added or \p false if the item with \p key
418 already is in the list.
420 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
422 template <typename Q, typename Func>
423 std::pair<bool, bool> ensure( Q const& key, Func f )
425 return ensure_at( head(), key, f );
428 /// Inserts data of type \ref value_type constructed from \p args
430 Returns \p true if inserting successful, \p false otherwise.
432 The function makes RCU lock internally.
434 template <typename... Args>
435 bool emplace( Args&&... args )
437 return emplace_at( head(), std::forward<Args>(args)... );
440 /// Deletes \p key from the list
441 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
442 Since the key of MichaelList's item type \p value_type is not explicitly specified,
443 template parameter \p Q defines the key type searching in the list.
444 The list item comparator should be able to compare values of the type \p value_type
445 and \p Q in any order.
447 RCU \p synchronize method can be called. RCU should not be locked.
449 Return \p true if key is found and deleted, \p false otherwise
451 template <typename Q>
452 bool erase( Q const& key )
454 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
457 /// Deletes the item from the list using \p pred predicate for searching
459 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
460 but \p pred is used for key comparing.
461 \p Less functor has the interface like \p std::less.
462 \p pred must imply the same element order as the comparator used for building the list.
464 template <typename Q, typename Less>
465 bool erase_with( Q const& key, Less pred )
468 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
471 /// Deletes \p key from the list
472 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
473 The function searches an item with key \p key, calls \p f functor with item found
474 and deletes it. If \p key is not found, the functor is not called.
476 The functor \p Func interface:
479 void operator()(const value_type& val) { ... }
483 Since the key of MichaelList's item type \p value_type is not explicitly specified,
484 template parameter \p Q defines the key type searching in the list.
485 The list item comparator should be able to compare the values of type \p value_type
486 and \p Q in any order.
488 RCU \p synchronize method can be called. RCU should not be locked.
490 Return \p true if key is found and deleted, \p false otherwise
492 template <typename Q, typename Func>
493 bool erase( Q const& key, Func f )
495 return erase_at( head(), key, intrusive_key_comparator(), f );
498 /// Deletes the item from the list using \p pred predicate for searching
500 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
501 but \p pred is used for key comparing.
502 \p Less functor has the interface like \p std::less.
503 \p pred must imply the same element order as the comparator used for building the list.
505 template <typename Q, typename Less, typename Func>
506 bool erase_with( Q const& key, Less pred, Func f )
509 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
512 /// Extracts an item from the list
514 @anchor cds_nonintrusive_MichaelList_rcu_extract
515 The function searches an item with key equal to \p key in the list,
516 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
517 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
519 @note The function does NOT dispose the item found. It just excludes the item from the list
520 and returns a pointer to item found.
521 You shouldn't lock RCU before calling this function.
524 #include <cds/urcu/general_buffered.h>
525 #include <cds/container/michael_list_rcu.h>
527 typedef cds::urcu::gc< general_buffered<> > rcu;
528 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
530 rcu_michael_list theList;
533 rcu_michael_list::exempt_ptr p;
535 // The RCU should NOT be locked when extract() is called!
536 assert( !rcu::is_locked() );
539 p = theList.extract( 10 )
541 // do something with p
545 // we may safely release extracted pointer here.
546 // release() passes the pointer to RCU reclamation cycle.
550 template <typename Q>
551 exempt_ptr extract( Q const& key )
553 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
556 /// Extracts an item from the list using \p pred predicate for searching
558 This function is the analog for \p extract(Q const&).
560 The \p pred is a predicate used for key comparing.
561 \p Less has the interface like \p std::less.
562 \p pred must imply the same element order as \ref key_comparator.
564 template <typename Q, typename Less>
565 exempt_ptr extract_with( Q const& key, Less pred )
568 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
571 /// Finds the key \p key
572 /** \anchor cds_nonintrusive_MichaelList_rcu_find_val
573 The function searches the item with key equal to \p key
574 and returns \p true if it is found, and \p false otherwise.
576 The function makes RCU lock internally.
578 template <typename Q>
579 bool find( Q const& key )
581 return find_at( head(), key, intrusive_key_comparator() );
584 /// Finds the key \p val using \p pred predicate for searching
586 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_val "find(Q const&)"
587 but \p pred is used for key comparing.
588 \p Less functor has the interface like \p std::less.
589 \p pred must imply the same element order as the comparator used for building the list.
591 template <typename Q, typename Less>
592 bool find_with( Q const& key, Less pred )
595 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
598 /// Finds the key \p key and performs an action with it
599 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
600 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
601 The interface of \p Func functor is:
604 void operator()( value_type& item, Q& key );
607 where \p item is the item found, \p key is the \p %find() function argument.
609 The functor may change non-key fields of \p item. Note that the function is only guarantee
610 that \p item cannot be deleted during functor is executing.
611 The function does not serialize simultaneous access to the list \p item. If such access is
612 possible you must provide your own synchronization schema to exclude unsafe item modifications.
614 The function makes RCU lock internally.
616 The function returns \p true if \p val is found, \p false otherwise.
618 template <typename Q, typename Func>
619 bool find( Q& key, Func f )
621 return find_at( head(), key, intrusive_key_comparator(), f );
624 template <typename Q, typename Func>
625 bool find( Q const& key, Func f )
627 return find_at( head(), key, intrusive_key_comparator(), f );
631 /// Finds the key \p key using \p pred predicate for searching
633 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
634 but \p pred is used for key comparing.
635 \p Less functor has the interface like \p std::less.
636 \p pred must imply the same element order as the comparator used for building the list.
638 template <typename Q, typename Less, typename Func>
639 bool find_with( Q& key, Less pred, Func f )
642 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
645 template <typename Q, typename Less, typename Func>
646 bool find_with( Q const& key, Less pred, Func f )
649 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
653 /// Finds the key \p key and return the item found
654 /** \anchor cds_nonintrusive_MichaelList_rcu_get
655 The function searches the item with key equal to \p key and returns the pointer to item found.
656 If \p key is not found it returns an empty \p raw_ptr.
658 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
660 RCU should be locked before call of this function.
661 Returned item is valid only while RCU is locked:
663 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
666 typename ord_list::raw_ptr rp;
669 ord_list::rcu_lock lock;
671 rp = theList.get( 5 );
676 // Unlock RCU by rcu_lock destructor
677 // A value owned by rp can be freed at any time after RCU has been unlocked
679 // You can manually release rp after RCU-locked section
683 template <typename Q>
684 raw_ptr get( Q const& key )
686 return get_at( head(), key, intrusive_key_comparator());
689 /// Finds \p key and return the item found
691 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
692 but \p pred is used for comparing the keys.
694 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
696 \p pred must imply the same element order as the comparator used for building the list.
698 template <typename Q, typename Less>
699 raw_ptr get_with( Q const& key, Less pred )
702 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
705 /// Checks if the list is empty
708 return base_class::empty();
711 /// Returns list's item count
713 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
714 this function always returns 0.
716 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
717 is empty. To check list emptyness use \p empty() method.
721 return base_class::size();
732 bool insert_node_at( head_type& refHead, node_type * pNode )
735 scoped_node_ptr p(pNode);
736 if ( base_class::insert_at( refHead, *pNode )) {
744 template <typename Q>
745 bool insert_at( head_type& refHead, Q const& val )
747 return insert_node_at( refHead, alloc_node( val ));
750 template <typename Q, typename Func>
751 bool insert_at( head_type& refHead, Q const& key, Func f )
753 scoped_node_ptr pNode( alloc_node( key ));
755 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
762 template <typename... Args>
763 bool emplace_at( head_type& refHead, Args&&... args )
765 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
768 template <typename Q, typename Compare, typename Func>
769 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
771 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
774 template <typename Q, typename Func>
775 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
777 scoped_node_ptr pNode( alloc_node( key ));
779 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
780 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
781 if ( ret.first && ret.second )
787 template <typename Q, typename Compare>
788 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
790 return base_class::extract_at( refHead, key, cmp );
793 template <typename Q, typename Compare>
794 bool find_at( head_type& refHead, Q const& key, Compare cmp )
796 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
799 template <typename Q, typename Compare, typename Func>
800 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
802 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
805 template <typename Q, typename Compare>
806 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
808 return raw_ptr( base_class::get_at( refHead, val, cmp ));
814 }} // namespace cds::container
816 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H