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 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer > exempt_ptr; ///< 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()
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()
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.
344 The user-defined functor can be passed by reference using \p std::ref
345 and it is called only if the inserting is success.
347 The type \p Q should contain the complete key of the node.
348 The object of \ref value_type should be constructible from \p key of type \p Q.
350 The function allows to split creating of new item into two part:
351 - create item from \p key with initializing key-fields only;
352 - insert new item into the list;
353 - if inserting is successful, initialize non-key fields of item by calling \p f functor
355 This can be useful if complete initialization of object of \p value_type is heavyweight and
356 it is preferable that the initialization should be completed only if inserting is successful.
358 The function makes RCU lock internally.
360 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
362 template <typename Q, typename Func>
363 bool insert( Q const& key, Func func )
365 return insert_at( head(), key, func );
368 /// Ensures that the \p key exists in the list
370 The operation performs inserting or changing data with lock-free manner.
372 If the \p key not found in the list, then the new item created from \p key
373 is inserted into the list. Otherwise, the functor \p func is called with the item found.
374 The functor \p Func should be a function with signature:
376 void func( bool bNew, value_type& item, const Q& val );
381 void operator()( bool bNew, value_type& item, const Q& val );
386 - \p bNew - \p true if the item has been inserted, \p false otherwise
387 - \p item - item of the list
388 - \p val - argument \p key passed into the \p ensure function
390 The functor may change non-key fields of the \p item; however, \p func must guarantee
391 that during changing no any other modifications could be made on this item by concurrent threads.
393 The function makes RCU lock internally.
395 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
396 \p second is true if new item has been added or \p false if the item with \p key
397 already is in the list.
399 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
401 template <typename Q, typename Func>
402 std::pair<bool, bool> ensure( Q const& key, Func f )
404 return ensure_at( head(), key, f );
407 /// Inserts data of type \ref value_type constructed from \p args
409 Returns \p true if inserting successful, \p false otherwise.
411 The function makes RCU lock internally.
413 template <typename... Args>
414 bool emplace( Args&&... args )
416 return emplace_at( head(), std::forward<Args>(args)... );
419 /// Deletes \p key from the list
420 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
421 Since the key of MichaelList's item type \p value_type is not explicitly specified,
422 template parameter \p Q defines the key type searching in the list.
423 The list item comparator should be able to compare values of the type \p value_type
424 and \p Q in any order.
426 RCU \p synchronize method can be called. RCU should not be locked.
428 Return \p true if key is found and deleted, \p false otherwise
430 template <typename Q>
431 bool erase( Q const& key )
433 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
436 /// Deletes the item from the list using \p pred predicate for searching
438 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
439 but \p pred is used for key comparing.
440 \p Less functor has the interface like \p std::less.
441 \p pred must imply the same element order as the comparator used for building the list.
443 template <typename Q, typename Less>
444 bool erase_with( Q const& key, Less pred )
446 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
449 /// Deletes \p key from the list
450 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
451 The function searches an item with key \p key, calls \p f functor with item found
452 and deletes it. If \p key is not found, the functor is not called.
454 The functor \p Func interface:
457 void operator()(const value_type& val) { ... }
461 Since the key of MichaelList's item type \p value_type is not explicitly specified,
462 template parameter \p Q defines the key type searching in the list.
463 The list item comparator should be able to compare the values of type \p value_type
464 and \p Q in any order.
466 RCU \p synchronize method can be called. RCU should not be locked.
468 Return \p true if key is found and deleted, \p false otherwise
470 template <typename Q, typename Func>
471 bool erase( Q const& key, Func f )
473 return erase_at( head(), key, intrusive_key_comparator(), f );
476 /// Deletes the item from the list using \p pred predicate for searching
478 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
479 but \p pred is used for key comparing.
480 \p Less functor has the interface like \p std::less.
481 \p pred must imply the same element order as the comparator used for building the list.
483 template <typename Q, typename Less, typename Func>
484 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 pointer to an item found in \p dest argument.
494 If the item with the key equal to \p key is not found the function returns \p false.
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 if ( theList.extract( p, 10 )) {
519 // do something with p
523 // Outside RCU lock section we may safely release extracted pointer.
524 // release() passes the pointer to RCU reclamation cycle.
528 template <typename Q>
529 bool extract( exempt_ptr& dest, Q const& key )
531 dest = extract_at( head(), key, intrusive_key_comparator() );
532 return !dest.empty();
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 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
546 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
547 return !dest.empty();
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
573 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
576 /// Finds the key \p key and performs an action with it
577 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
578 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
579 The interface of \p Func functor is:
582 void operator()( value_type& item, Q& key );
585 where \p item is the item found, \p key is the \p %find() function argument.
587 The functor may change non-key fields of \p item. Note that the function is only guarantee
588 that \p item cannot be deleted during functor is executing.
589 The function does not serialize simultaneous access to the list \p item. If such access is
590 possible you must provide your own synchronization schema to exclude unsafe item modifications.
592 The function makes RCU lock internally.
594 The function returns \p true if \p val is found, \p false otherwise.
596 template <typename Q, typename Func>
597 bool find( Q& key, Func f ) const
599 return find_at( head(), key, intrusive_key_comparator(), f );
602 /// Finds the key \p key using \p pred predicate for searching
604 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
605 but \p pred is used for key comparing.
606 \p Less functor has the interface like \p std::less.
607 \p pred must imply the same element order as the comparator used for building the list.
609 template <typename Q, typename Less, typename Func>
610 bool find_with( Q& key, Less pred, Func f ) const
612 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
615 /// Finds the key \p key and return the item found
616 /** \anchor cds_nonintrusive_MichaelList_rcu_get
617 The function searches the item with key equal to \p key and returns the pointer to item found.
618 If \p key is not found it returns \p nullptr.
620 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
622 RCU should be locked before call of this function.
623 Returned item is valid only while RCU is locked:
625 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
630 ord_list::rcu_lock lock;
632 foo * pVal = theList.get( 5 );
637 // Unlock RCU by rcu_lock destructor
638 // pVal can be freed at any time after RCU has been unlocked
642 template <typename Q>
643 value_type * get( Q const& key ) const
645 return get_at( head(), key, intrusive_key_comparator());
648 /// Finds \p key and return the item found
650 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
651 but \p pred is used for comparing the keys.
653 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
655 \p pred must imply the same element order as the comparator used for building the list.
657 template <typename Q, typename Less>
658 value_type * get_with( Q const& key, Less pred ) const
660 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
663 /// Checks if the list is empty
666 return base_class::empty();
669 /// Returns list's item count
671 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
672 this function always returns 0.
674 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
675 is empty. To check list emptyness use \p empty() method.
679 return base_class::size();
690 bool insert_node_at( head_type& refHead, node_type * pNode )
693 scoped_node_ptr p(pNode);
694 if ( base_class::insert_at( refHead, *pNode )) {
702 template <typename Q>
703 bool insert_at( head_type& refHead, Q const& val )
705 return insert_node_at( refHead, alloc_node( val ));
708 template <typename Q, typename Func>
709 bool insert_at( head_type& refHead, Q const& key, Func f )
711 scoped_node_ptr pNode( alloc_node( key ));
713 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
720 template <typename... Args>
721 bool emplace_at( head_type& refHead, Args&&... args )
723 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
726 template <typename Q, typename Compare, typename Func>
727 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
729 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
732 template <typename Q, typename Func>
733 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
735 scoped_node_ptr pNode( alloc_node( key ));
737 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
738 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
739 if ( ret.first && ret.second )
745 template <typename Q, typename Compare>
746 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
748 return base_class::extract_at( refHead, key, cmp );
751 template <typename Q, typename Compare>
752 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
754 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
757 template <typename Q, typename Compare, typename Func>
758 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
760 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
763 template <typename Q, typename Compare>
764 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
766 node_type * pNode = base_class::get_at( refHead, val, cmp );
767 return pNode ? &pNode->m_Value : nullptr;
773 }} // namespace cds::container
775 #endif // #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H