3 #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H
4 #define __CDS_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 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
143 static value_type& node_to_value( node_type& n )
147 static value_type const& node_to_value( node_type const& n )
155 template <typename Q>
156 static node_type * alloc_node( Q const& v )
158 return cxx_allocator().New( v );
161 template <typename... Args>
162 static node_type * alloc_node( Args&&... args )
164 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
167 static void free_node( node_type * pNode )
169 cxx_allocator().Delete( pNode );
172 struct node_disposer {
173 void operator()( node_type * pNode )
178 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
182 return base_class::m_pHead;
185 head_type& head() const
187 return const_cast<head_type&>( base_class::m_pHead );
193 template <bool IsConst>
194 class iterator_type: protected base_class::template iterator_type<IsConst>
196 typedef typename base_class::template iterator_type<IsConst> iterator_base;
198 iterator_type( head_type const& pNode )
199 : iterator_base( pNode )
202 friend class MichaelList;
205 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
206 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
211 iterator_type( iterator_type const& src )
212 : iterator_base( src )
215 value_ptr operator ->() const
217 typename iterator_base::value_ptr p = iterator_base::operator ->();
218 return p ? &(p->m_Value) : nullptr;
221 value_ref operator *() const
223 return (iterator_base::operator *()).m_Value;
227 iterator_type& operator ++()
229 iterator_base::operator ++();
234 bool operator ==(iterator_type<C> const& i ) const
236 return iterator_base::operator ==(i);
239 bool operator !=(iterator_type<C> const& i ) const
241 return iterator_base::operator !=(i);
248 typedef iterator_type<false> iterator;
250 /// Const forward iterator
251 typedef iterator_type<true> const_iterator;
253 /// Returns a forward iterator addressing the first element in a list
255 For empty list \code begin() == end() \endcode
259 return iterator( head() );
262 /// Returns an iterator that addresses the location succeeding the last element in a list
264 Do not use the value returned by <tt>end</tt> function to access any item.
265 Internally, <tt>end</tt> returning value equals to \p nullptr.
267 The returned value can be used only to control reaching the end of the list.
268 For empty list \code begin() == end() \endcode
275 /// Returns a forward const iterator addressing the first element in a list
277 const_iterator begin() const
279 return const_iterator( head() );
281 const_iterator cbegin() const
283 return const_iterator( head() );
287 /// Returns an const iterator that addresses the location succeeding the last element in a list
289 const_iterator end() const
291 return const_iterator();
293 const_iterator cend() const
295 return const_iterator();
300 /// Default constructor
302 Initialize empty list
318 The function creates a node with copy of \p val value
319 and then inserts the node created into the list.
321 The type \p Q should contain as minimum the complete key of the node.
322 The object of \ref value_type should be constructible from \p val of type \p Q.
323 In trivial case, \p Q is equal to \ref value_type.
325 The function makes RCU lock internally.
327 Returns \p true if inserting successful, \p false otherwise.
329 template <typename Q>
330 bool insert( Q const& val )
332 return insert_at( head(), val );
337 This function inserts new node with default-constructed value and then it calls
338 \p func functor with signature
339 \code void func( value_type& itemValue ) ;\endcode
341 The argument \p itemValue of user-defined functor \p func is the reference
342 to the list's item inserted. User-defined functor \p func should guarantee that during changing
343 item's value no any other changes could be made on this list's item by concurrent threads.
345 The type \p Q should contain the complete key of the node.
346 The object of \ref 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 f functor
353 This 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 The function makes RCU lock internally.
358 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
360 template <typename Q, typename Func>
361 bool insert( Q const& key, Func func )
363 return insert_at( head(), key, func );
366 /// Ensures that the \p key exists in the list
368 The operation performs inserting or changing data with lock-free manner.
370 If the \p key not found in the list, then the new item created from \p key
371 is inserted into the list. Otherwise, the functor \p func is called with the item found.
372 The functor \p Func should be a function with signature:
374 void func( bool bNew, value_type& item, const Q& val );
379 void operator()( bool bNew, value_type& item, const Q& val );
384 - \p bNew - \p true if the item has been inserted, \p false otherwise
385 - \p item - item of the list
386 - \p val - argument \p key passed into the \p ensure function
388 The functor may change non-key fields of the \p item; however, \p func must guarantee
389 that during changing no any other modifications could be made on this item by concurrent threads.
391 The function makes RCU lock internally.
393 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
394 \p second is true if new item has been added or \p false if the item with \p key
395 already is in the list.
397 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
399 template <typename Q, typename Func>
400 std::pair<bool, bool> ensure( Q const& key, Func f )
402 return ensure_at( head(), key, f );
405 /// Inserts data of type \ref value_type constructed from \p args
407 Returns \p true if inserting successful, \p false otherwise.
409 The function makes RCU lock internally.
411 template <typename... Args>
412 bool emplace( Args&&... args )
414 return emplace_at( head(), std::forward<Args>(args)... );
417 /// Deletes \p key from the list
418 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
419 Since the key of MichaelList's item type \p value_type is not explicitly specified,
420 template parameter \p Q defines the key type searching in the list.
421 The list item comparator should be able to compare values of the type \p value_type
422 and \p Q in any order.
424 RCU \p synchronize method can be called. RCU should not be locked.
426 Return \p true if key is found and deleted, \p false otherwise
428 template <typename Q>
429 bool erase( Q const& key )
431 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
434 /// Deletes the item from the list using \p pred predicate for searching
436 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
437 but \p pred is used for key comparing.
438 \p Less functor has the interface like \p std::less.
439 \p pred must imply the same element order as the comparator used for building the list.
441 template <typename Q, typename Less>
442 bool erase_with( Q const& key, Less pred )
445 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
448 /// Deletes \p key from the list
449 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
450 The function searches an item with key \p key, calls \p f functor with item found
451 and deletes it. If \p key is not found, the functor is not called.
453 The functor \p Func interface:
456 void operator()(const value_type& val) { ... }
460 Since the key of MichaelList's item type \p value_type is not explicitly specified,
461 template parameter \p Q defines the key type searching in the list.
462 The list item comparator should be able to compare the values of type \p value_type
463 and \p Q in any order.
465 RCU \p synchronize method can be called. RCU should not be locked.
467 Return \p true if key is found and deleted, \p false otherwise
469 template <typename Q, typename Func>
470 bool erase( Q const& key, Func f )
472 return erase_at( head(), key, intrusive_key_comparator(), f );
475 /// Deletes the item from the list using \p pred predicate for searching
477 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
478 but \p pred is used for key comparing.
479 \p Less functor has the interface like \p std::less.
480 \p pred must imply the same element order as the comparator used for building the list.
482 template <typename Q, typename Less, typename Func>
483 bool erase_with( Q const& key, Less pred, Func f )
486 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
489 /// Extracts an item from the list
491 @anchor cds_nonintrusive_MichaelList_rcu_extract
492 The function searches an item with key equal to \p key in the list,
493 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
494 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
496 @note The function does NOT call RCU read-side lock or synchronization,
497 and does NOT dispose the item found. It just excludes the item from the list
498 and returns a pointer to item found.
499 You should lock RCU before calling this function.
502 #include <cds/urcu/general_buffered.h>
503 #include <cds/container/michael_list_rcu.h>
505 typedef cds::urcu::gc< general_buffered<> > rcu;
506 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
508 rcu_michael_list theList;
511 rcu_michael_list::exempt_ptr p;
513 // first, we should lock RCU
516 // Now, you can apply extract function
517 // Note that you must not delete the item found inside the RCU lock
518 p = theList.extract( 10 )
520 // do something with p
524 // Outside RCU lock section we may safely release extracted pointer.
525 // release() passes the pointer to RCU reclamation cycle.
529 template <typename Q>
530 exempt_ptr extract( Q const& key )
532 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
535 /// Extracts an item from the list using \p pred predicate for searching
537 This function is the analog for \ref cds_nonintrusive_MichaelList_rcu_extract "extract(exempt_ptr&, Q const&)".
539 The \p pred is a predicate used for key comparing.
540 \p Less has the interface like \p std::less.
541 \p pred must imply the same element order as \ref key_comparator.
543 template <typename Q, typename Less>
544 exempt_ptr extract_with( Q const& key, Less pred )
547 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
550 /// Finds the key \p key
551 /** \anchor cds_nonintrusive_MichaelList_rcu_find_val
552 The function searches the item with key equal to \p key
553 and returns \p true if it is found, and \p false otherwise.
555 The function makes RCU lock internally.
557 template <typename Q>
558 bool find( Q const& key ) const
560 return find_at( head(), key, intrusive_key_comparator() );
563 /// Finds the key \p val using \p pred predicate for searching
565 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_val "find(Q const&)"
566 but \p pred is used for key comparing.
567 \p Less functor has the interface like \p std::less.
568 \p pred must imply the same element order as the comparator used for building the list.
570 template <typename Q, typename Less>
571 bool find_with( Q const& key, Less pred ) const
574 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
577 /// Finds the key \p key and performs an action with it
578 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
579 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
580 The interface of \p Func functor is:
583 void operator()( value_type& item, Q& key );
586 where \p item is the item found, \p key is the \p %find() function argument.
588 The functor may change non-key fields of \p item. Note that the function is only guarantee
589 that \p item cannot be deleted during functor is executing.
590 The function does not serialize simultaneous access to the list \p item. If such access is
591 possible you must provide your own synchronization schema to exclude unsafe item modifications.
593 The function makes RCU lock internally.
595 The function returns \p true if \p val is found, \p false otherwise.
597 template <typename Q, typename Func>
598 bool find( Q& key, Func f ) const
600 return find_at( head(), key, intrusive_key_comparator(), f );
603 template <typename Q, typename Func>
604 bool find( Q const& key, Func f ) const
606 return find_at( head(), key, intrusive_key_comparator(), f );
610 /// Finds the key \p key using \p pred predicate for searching
612 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
613 but \p pred is used for key comparing.
614 \p Less functor has the interface like \p std::less.
615 \p pred must imply the same element order as the comparator used for building the list.
617 template <typename Q, typename Less, typename Func>
618 bool find_with( Q& key, Less pred, Func f ) const
621 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
624 template <typename Q, typename Less, typename Func>
625 bool find_with( Q const& key, Less pred, Func f ) const
628 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
632 /// Finds the key \p key and return the item found
633 /** \anchor cds_nonintrusive_MichaelList_rcu_get
634 The function searches the item with key equal to \p key and returns the pointer to item found.
635 If \p key is not found it returns \p nullptr.
637 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
639 RCU should be locked before call of this function.
640 Returned item is valid only while RCU is locked:
642 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
647 ord_list::rcu_lock lock;
649 foo * pVal = theList.get( 5 );
654 // Unlock RCU by rcu_lock destructor
655 // pVal can be freed at any time after RCU has been unlocked
659 template <typename Q>
660 value_type * get( Q const& key ) const
662 return get_at( head(), key, intrusive_key_comparator());
665 /// Finds \p key and return the item found
667 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
668 but \p pred is used for comparing the keys.
670 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
672 \p pred must imply the same element order as the comparator used for building the list.
674 template <typename Q, typename Less>
675 value_type * get_with( Q const& key, Less pred ) const
678 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
681 /// Checks if the list is empty
684 return base_class::empty();
687 /// Returns list's item count
689 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
690 this function always returns 0.
692 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
693 is empty. To check list emptyness use \p empty() method.
697 return base_class::size();
708 bool insert_node_at( head_type& refHead, node_type * pNode )
711 scoped_node_ptr p(pNode);
712 if ( base_class::insert_at( refHead, *pNode )) {
720 template <typename Q>
721 bool insert_at( head_type& refHead, Q const& val )
723 return insert_node_at( refHead, alloc_node( val ));
726 template <typename Q, typename Func>
727 bool insert_at( head_type& refHead, Q const& key, Func f )
729 scoped_node_ptr pNode( alloc_node( key ));
731 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
738 template <typename... Args>
739 bool emplace_at( head_type& refHead, Args&&... args )
741 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
744 template <typename Q, typename Compare, typename Func>
745 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
747 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
750 template <typename Q, typename Func>
751 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
753 scoped_node_ptr pNode( alloc_node( key ));
755 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
756 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
757 if ( ret.first && ret.second )
763 template <typename Q, typename Compare>
764 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
766 return base_class::extract_at( refHead, key, cmp );
769 template <typename Q, typename Compare>
770 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
772 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
775 template <typename Q, typename Compare, typename Func>
776 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
778 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
781 template <typename Q, typename Compare>
782 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
784 node_type * pNode = base_class::get_at( refHead, val, cmp );
785 return pNode ? &pNode->m_Value : nullptr;
791 }} // namespace cds::container
793 #endif // #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H