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
143 struct raw_ptr_converter
145 value_type * operator()( node_type * p ) const
147 return p ? &p->m_Value : nullptr;
150 value_type& operator()( node_type& n ) const
155 value_type const& operator()( node_type const& n ) const
163 /// Result of \p get(), \p get_with() functions - pointer to the node found
164 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
168 static value_type& node_to_value( node_type& n )
172 static value_type const& node_to_value( node_type const& n )
180 template <typename Q>
181 static node_type * alloc_node( Q const& v )
183 return cxx_allocator().New( v );
186 template <typename... Args>
187 static node_type * alloc_node( Args&&... args )
189 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
192 static void free_node( node_type * pNode )
194 cxx_allocator().Delete( pNode );
197 struct node_disposer {
198 void operator()( node_type * pNode )
203 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
207 return base_class::m_pHead;
210 head_type& head() const
212 return const_cast<head_type&>( base_class::m_pHead );
218 template <bool IsConst>
219 class iterator_type: protected base_class::template iterator_type<IsConst>
221 typedef typename base_class::template iterator_type<IsConst> iterator_base;
223 iterator_type( head_type const& pNode )
224 : iterator_base( pNode )
227 friend class MichaelList;
230 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
231 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
236 iterator_type( iterator_type const& src )
237 : iterator_base( src )
240 value_ptr operator ->() const
242 typename iterator_base::value_ptr p = iterator_base::operator ->();
243 return p ? &(p->m_Value) : nullptr;
246 value_ref operator *() const
248 return (iterator_base::operator *()).m_Value;
252 iterator_type& operator ++()
254 iterator_base::operator ++();
259 bool operator ==(iterator_type<C> const& i ) const
261 return iterator_base::operator ==(i);
264 bool operator !=(iterator_type<C> const& i ) const
266 return iterator_base::operator !=(i);
273 typedef iterator_type<false> iterator;
275 /// Const forward iterator
276 typedef iterator_type<true> const_iterator;
278 /// Returns a forward iterator addressing the first element in a list
280 For empty list \code begin() == end() \endcode
284 return iterator( head() );
287 /// Returns an iterator that addresses the location succeeding the last element in a list
289 Do not use the value returned by <tt>end</tt> function to access any item.
290 Internally, <tt>end</tt> returning value equals to \p nullptr.
292 The returned value can be used only to control reaching the end of the list.
293 For empty list \code begin() == end() \endcode
300 /// Returns a forward const iterator addressing the first element in a list
302 const_iterator begin() const
304 return const_iterator( head() );
306 const_iterator cbegin() const
308 return const_iterator( head() );
312 /// Returns an const iterator that addresses the location succeeding the last element in a list
314 const_iterator end() const
316 return const_iterator();
318 const_iterator cend() const
320 return const_iterator();
325 /// Default constructor
327 Initialize empty list
343 The function creates a node with copy of \p val value
344 and then inserts the node created into the list.
346 The type \p Q should contain as minimum the complete key of the node.
347 The object of \ref value_type should be constructible from \p val of type \p Q.
348 In trivial case, \p Q is equal to \ref value_type.
350 The function makes RCU lock internally.
352 Returns \p true if inserting successful, \p false otherwise.
354 template <typename Q>
355 bool insert( Q const& val )
357 return insert_at( head(), val );
362 This function inserts new node with default-constructed value and then it calls
363 \p func functor with signature
364 \code void func( value_type& itemValue ) ;\endcode
366 The argument \p itemValue of user-defined functor \p func is the reference
367 to the list's item inserted. User-defined functor \p func should guarantee that during changing
368 item's value no any other changes could be made on this list's item by concurrent threads.
370 The type \p Q should contain the complete key of the node.
371 The object of \ref value_type should be constructible from \p key of type \p Q.
373 The function allows to split creating of new item into two part:
374 - create item from \p key with initializing key-fields only;
375 - insert new item into the list;
376 - if inserting is successful, initialize non-key fields of item by calling \p f functor
378 This can be useful if complete initialization of object of \p value_type is heavyweight and
379 it is preferable that the initialization should be completed only if inserting is successful.
381 The function makes RCU lock internally.
383 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
385 template <typename Q, typename Func>
386 bool insert( Q const& key, Func func )
388 return insert_at( head(), key, func );
391 /// Updates data by \p key
393 The operation performs inserting or replacing the element with lock-free manner.
395 If the \p key not found in the list, then the new item created from \p key
396 will be inserted iff \p bAllowInsert is \p true.
397 Otherwise, if \p key is found, the functor \p func is called with item found.
399 The functor \p Func signature is:
402 void operator()( bool bNew, value_type& item, Q const& 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 %update() 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 applies 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
420 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
422 template <typename Q, typename Func>
423 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
425 return update_at( head(), key, func, bAllowInsert );
428 template <typename Q, typename Func>
429 CDS_DEPRECATED("ensure() is deprecated, use update()")
430 std::pair<bool, bool> ensure( Q const& key, Func f )
432 return update( key, f, true );
436 /// Inserts data of type \ref value_type constructed from \p args
438 Returns \p true if inserting successful, \p false otherwise.
440 The function makes RCU lock internally.
442 template <typename... Args>
443 bool emplace( Args&&... args )
445 return emplace_at( head(), std::forward<Args>(args)... );
448 /// Deletes \p key from the list
449 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
450 Since the key of MichaelList's item type \p value_type is not explicitly specified,
451 template parameter \p Q defines the key type searching in the list.
452 The list item comparator should be able to compare values of the type \p value_type
453 and \p Q in any order.
455 RCU \p synchronize method can be called. RCU should not be locked.
457 Return \p true if key is found and deleted, \p false otherwise
459 template <typename Q>
460 bool erase( Q const& key )
462 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
465 /// Deletes the item from the list using \p pred predicate for searching
467 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
468 but \p pred is used for key comparing.
469 \p Less functor has the interface like \p std::less.
470 \p pred must imply the same element order as the comparator used for building the list.
472 template <typename Q, typename Less>
473 bool erase_with( Q const& key, Less pred )
476 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
479 /// Deletes \p key from the list
480 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
481 The function searches an item with key \p key, calls \p f functor with item found
482 and deletes it. If \p key is not found, the functor is not called.
484 The functor \p Func interface:
487 void operator()(const value_type& val) { ... }
491 Since the key of MichaelList's item type \p value_type is not explicitly specified,
492 template parameter \p Q defines the key type searching in the list.
493 The list item comparator should be able to compare the values of type \p value_type
494 and \p Q in any order.
496 RCU \p synchronize method can be called. RCU should not be locked.
498 Return \p true if key is found and deleted, \p false otherwise
500 template <typename Q, typename Func>
501 bool erase( Q const& key, Func f )
503 return erase_at( head(), key, intrusive_key_comparator(), f );
506 /// Deletes the item from the list using \p pred predicate for searching
508 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
509 but \p pred is used for key comparing.
510 \p Less functor has the interface like \p std::less.
511 \p pred must imply the same element order as the comparator used for building the list.
513 template <typename Q, typename Less, typename Func>
514 bool erase_with( Q const& key, Less pred, Func f )
517 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
520 /// Extracts an item from the list
522 @anchor cds_nonintrusive_MichaelList_rcu_extract
523 The function searches an item with key equal to \p key in the list,
524 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
525 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
527 @note The function does NOT dispose the item found. It just excludes the item from the list
528 and returns a pointer to the item.
529 You shouldn't lock RCU for current thread before calling this function.
532 #include <cds/urcu/general_buffered.h>
533 #include <cds/container/michael_list_rcu.h>
535 typedef cds::urcu::gc< general_buffered<> > rcu;
536 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
538 rcu_michael_list theList;
541 rcu_michael_list::exempt_ptr p;
543 // The RCU should NOT be locked when extract() is called!
544 assert( !rcu::is_locked() );
547 p = theList.extract( 10 )
549 // do something with p
553 // we may safely release extracted pointer here.
554 // release() passes the pointer to RCU reclamation cycle.
558 template <typename Q>
559 exempt_ptr extract( Q const& key )
561 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
564 /// Extracts an item from the list using \p pred predicate for searching
566 This function is the analog for \p extract(Q const&).
568 The \p pred is a predicate used for key comparing.
569 \p Less has the interface like \p std::less.
570 \p pred must imply the same element order as \ref key_comparator.
572 template <typename Q, typename Less>
573 exempt_ptr extract_with( Q const& key, Less pred )
576 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
579 /// Checks whether the list contains \p key
581 The function searches the item with key equal to \p key
582 and returns \p true if it is found, and \p false otherwise.
584 The function applies RCU lock internally.
586 template <typename Q>
587 bool contains( Q const& key )
589 return find_at( head(), key, intrusive_key_comparator() );
592 template <typename Q>
593 CDS_DEPRECATED("deprecated, use contains()")
594 bool find( Q const& key )
596 return contains( key );
600 /// Checks whether the list contains \p key using \p pred predicate for searching
602 The function is an analog of <tt>contains( key )</tt> 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>
607 bool contains( Q const& key, Less pred )
610 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
613 // Deprecatd, use contains()
614 template <typename Q, typename Less>
615 bool find_with( Q const& key, Less pred )
618 return contains( key, pred );
622 /// Finds the key \p key and performs an action with it
623 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
624 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
625 The interface of \p Func functor is:
628 void operator()( value_type& item, Q& key );
631 where \p item is the item found, \p key is the \p %find() function argument.
633 The functor may change non-key fields of \p item. Note that the function is only guarantee
634 that \p item cannot be deleted during functor is executing.
635 The function does not serialize simultaneous access to the list \p item. If such access is
636 possible you must provide your own synchronization schema to exclude unsafe item modifications.
638 The function makes RCU lock internally.
640 The function returns \p true if \p val is found, \p false otherwise.
642 template <typename Q, typename Func>
643 bool find( Q& key, Func f )
645 return find_at( head(), key, intrusive_key_comparator(), f );
648 template <typename Q, typename Func>
649 bool find( Q const& key, Func f )
651 return find_at( head(), key, intrusive_key_comparator(), f );
655 /// Finds the key \p key using \p pred predicate for searching
657 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
658 but \p pred is used for key comparing.
659 \p Less functor has the interface like \p std::less.
660 \p pred must imply the same element order as the comparator used for building the list.
662 template <typename Q, typename Less, typename Func>
663 bool find_with( Q& key, Less pred, Func f )
666 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
669 template <typename Q, typename Less, typename Func>
670 bool find_with( Q const& key, Less pred, Func f )
673 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
677 /// Finds the key \p key and return the item found
678 /** \anchor cds_nonintrusive_MichaelList_rcu_get
679 The function searches the item with key equal to \p key and returns the pointer to item found.
680 If \p key is not found it returns an empty \p raw_ptr.
682 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
684 RCU should be locked before call of this function.
685 Returned item is valid only while RCU is locked:
687 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
690 typename ord_list::raw_ptr rp;
693 ord_list::rcu_lock lock;
695 rp = theList.get( 5 );
700 // Unlock RCU by rcu_lock destructor
701 // A value owned by rp can be freed at any time after RCU has been unlocked
703 // You can manually release rp after RCU-locked section
707 template <typename Q>
708 raw_ptr get( Q const& key )
710 return get_at( head(), key, intrusive_key_comparator());
713 /// Finds \p key and return the item found
715 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
716 but \p pred is used for comparing the keys.
718 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
720 \p pred must imply the same element order as the comparator used for building the list.
722 template <typename Q, typename Less>
723 raw_ptr get_with( Q const& key, Less pred )
726 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
729 /// Checks if the list is empty
732 return base_class::empty();
735 /// Returns list's item count
737 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
738 this function always returns 0.
740 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
741 is empty. To check list emptyness use \p empty() method.
745 return base_class::size();
756 bool insert_node_at( head_type& refHead, node_type * pNode )
759 scoped_node_ptr p(pNode);
760 if ( base_class::insert_at( refHead, *pNode )) {
768 template <typename Q>
769 bool insert_at( head_type& refHead, Q const& val )
771 return insert_node_at( refHead, alloc_node( val ));
774 template <typename Q, typename Func>
775 bool insert_at( head_type& refHead, Q const& key, Func f )
777 scoped_node_ptr pNode( alloc_node( key ));
779 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
786 template <typename... Args>
787 bool emplace_at( head_type& refHead, Args&&... args )
789 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
792 template <typename Q, typename Compare, typename Func>
793 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
795 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
798 template <typename Q, typename Func>
799 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
801 scoped_node_ptr pNode( alloc_node( key ));
803 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
804 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
806 if ( ret.first && ret.second )
812 template <typename Q, typename Compare>
813 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
815 return base_class::extract_at( refHead, key, cmp );
818 template <typename Q, typename Compare>
819 bool find_at( head_type& refHead, Q const& key, Compare cmp )
821 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
824 template <typename Q, typename Compare, typename Func>
825 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
827 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
830 template <typename Q, typename Compare>
831 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
833 return raw_ptr( base_class::get_at( refHead, val, cmp ));
839 }} // namespace cds::container
841 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H