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 )
444 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
447 /// Deletes \p key from the list
448 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
449 The function searches an item with key \p key, calls \p f functor with item found
450 and deletes it. If \p key is not found, the functor is not called.
452 The functor \p Func interface:
455 void operator()(const value_type& val) { ... }
459 Since the key of MichaelList's item type \p value_type is not explicitly specified,
460 template parameter \p Q defines the key type searching in the list.
461 The list item comparator should be able to compare the values of type \p value_type
462 and \p Q in any order.
464 RCU \p synchronize method can be called. RCU should not be locked.
466 Return \p true if key is found and deleted, \p false otherwise
468 template <typename Q, typename Func>
469 bool erase( Q const& key, Func f )
471 return erase_at( head(), key, intrusive_key_comparator(), f );
474 /// Deletes the item from the list using \p pred predicate for searching
476 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
477 but \p pred is used for key comparing.
478 \p Less functor has the interface like \p std::less.
479 \p pred must imply the same element order as the comparator used for building the list.
481 template <typename Q, typename Less, typename Func>
482 bool erase_with( Q const& key, Less pred, Func f )
484 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
487 /// Extracts an item from the list
489 @anchor cds_nonintrusive_MichaelList_rcu_extract
490 The function searches an item with key equal to \p key in the list,
491 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
492 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
494 @note The function does NOT call RCU read-side lock or synchronization,
495 and does NOT dispose the item found. It just excludes the item from the list
496 and returns a pointer to item found.
497 You should lock RCU before calling this function.
500 #include <cds/urcu/general_buffered.h>
501 #include <cds/container/michael_list_rcu.h>
503 typedef cds::urcu::gc< general_buffered<> > rcu;
504 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
506 rcu_michael_list theList;
509 rcu_michael_list::exempt_ptr p;
511 // first, we should lock RCU
514 // Now, you can apply extract function
515 // Note that you must not delete the item found inside the RCU lock
516 p = theList.extract( 10 )
518 // do something with p
522 // Outside RCU lock section we may safely release extracted pointer.
523 // release() passes the pointer to RCU reclamation cycle.
527 template <typename Q>
528 exempt_ptr extract( Q const& key )
530 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
533 /// Extracts an item from the list using \p pred predicate for searching
535 This function is the analog for \ref cds_nonintrusive_MichaelList_rcu_extract "extract(exempt_ptr&, Q const&)".
537 The \p pred is a predicate used for key comparing.
538 \p Less has the interface like \p std::less.
539 \p pred must imply the same element order as \ref key_comparator.
541 template <typename Q, typename Less>
542 exempt_ptr extract_with( Q const& key, Less pred )
544 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
547 /// Finds the key \p key
548 /** \anchor cds_nonintrusive_MichaelList_rcu_find_val
549 The function searches the item with key equal to \p key
550 and returns \p true if it is found, and \p false otherwise.
552 The function makes RCU lock internally.
554 template <typename Q>
555 bool find( Q const& key ) const
557 return find_at( head(), key, intrusive_key_comparator() );
560 /// Finds the key \p val using \p pred predicate for searching
562 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_val "find(Q const&)"
563 but \p pred is used for key comparing.
564 \p Less functor has the interface like \p std::less.
565 \p pred must imply the same element order as the comparator used for building the list.
567 template <typename Q, typename Less>
568 bool find_with( Q const& key, Less pred ) const
570 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
573 /// Finds the key \p key and performs an action with it
574 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
575 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
576 The interface of \p Func functor is:
579 void operator()( value_type& item, Q& key );
582 where \p item is the item found, \p key is the \p %find() function argument.
584 The functor may change non-key fields of \p item. Note that the function is only guarantee
585 that \p item cannot be deleted during functor is executing.
586 The function does not serialize simultaneous access to the list \p item. If such access is
587 possible you must provide your own synchronization schema to exclude unsafe item modifications.
589 The function makes RCU lock internally.
591 The function returns \p true if \p val is found, \p false otherwise.
593 template <typename Q, typename Func>
594 bool find( Q& key, Func f ) const
596 return find_at( head(), key, intrusive_key_comparator(), f );
599 /// Finds the key \p key using \p pred predicate for searching
601 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
602 but \p pred is used for key comparing.
603 \p Less functor has the interface like \p std::less.
604 \p pred must imply the same element order as the comparator used for building the list.
606 template <typename Q, typename Less, typename Func>
607 bool find_with( Q& key, Less pred, Func f ) const
609 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
612 /// Finds the key \p key and return the item found
613 /** \anchor cds_nonintrusive_MichaelList_rcu_get
614 The function searches the item with key equal to \p key and returns the pointer to item found.
615 If \p key is not found it returns \p nullptr.
617 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
619 RCU should be locked before call of this function.
620 Returned item is valid only while RCU is locked:
622 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
627 ord_list::rcu_lock lock;
629 foo * pVal = theList.get( 5 );
634 // Unlock RCU by rcu_lock destructor
635 // pVal can be freed at any time after RCU has been unlocked
639 template <typename Q>
640 value_type * get( Q const& key ) const
642 return get_at( head(), key, intrusive_key_comparator());
645 /// Finds \p key and return the item found
647 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
648 but \p pred is used for comparing the keys.
650 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
652 \p pred must imply the same element order as the comparator used for building the list.
654 template <typename Q, typename Less>
655 value_type * get_with( Q const& key, Less pred ) const
657 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
660 /// Checks if the list is empty
663 return base_class::empty();
666 /// Returns list's item count
668 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
669 this function always returns 0.
671 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
672 is empty. To check list emptyness use \p empty() method.
676 return base_class::size();
687 bool insert_node_at( head_type& refHead, node_type * pNode )
690 scoped_node_ptr p(pNode);
691 if ( base_class::insert_at( refHead, *pNode )) {
699 template <typename Q>
700 bool insert_at( head_type& refHead, Q const& val )
702 return insert_node_at( refHead, alloc_node( val ));
705 template <typename Q, typename Func>
706 bool insert_at( head_type& refHead, Q const& key, Func f )
708 scoped_node_ptr pNode( alloc_node( key ));
710 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
717 template <typename... Args>
718 bool emplace_at( head_type& refHead, Args&&... args )
720 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
723 template <typename Q, typename Compare, typename Func>
724 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
726 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
729 template <typename Q, typename Func>
730 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
732 scoped_node_ptr pNode( alloc_node( key ));
734 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
735 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
736 if ( ret.first && ret.second )
742 template <typename Q, typename Compare>
743 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
745 return base_class::extract_at( refHead, key, cmp );
748 template <typename Q, typename Compare>
749 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
751 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
754 template <typename Q, typename Compare, typename Func>
755 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
757 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
760 template <typename Q, typename Compare>
761 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
763 node_type * pNode = base_class::get_at( refHead, val, cmp );
764 return pNode ? &pNode->m_Value : nullptr;
770 }} // namespace cds::container
772 #endif // #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H