2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
32 #define CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
35 #include <cds/container/details/michael_list_base.h>
36 #include <cds/intrusive/michael_list_rcu.h>
37 #include <cds/container/details/make_michael_list.h>
38 #include <cds/details/binary_functor_wrapper.h>
40 namespace cds { namespace container {
42 /// Michael's ordered list (template specialization for \ref cds_urcu_desc "RCU")
43 /** @ingroup cds_nonintrusive_list
44 \anchor cds_nonintrusive_MichaelList_rcu
46 Usually, ordered single-linked list is used as a building block for the hash table implementation.
47 The complexity of searching is <tt>O(N)</tt>.
50 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
52 This class is non-intrusive version of \ref cds_intrusive_MichaelList_rcu "cds::intrusive::MichaelList" RCU specialization.
55 - \p RCU - one of \ref cds_urcu_gc "RCU type"
56 - \p T - type stored in the list. The type must be default- and copy-constructible.
57 - \p Traits - type traits, default is michael_list::traits
59 The implementation does not divide type \p T into key and value part and
60 may be used as a main building block for hash set containers.
61 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
62 or <tt>Traits::less</tt> predicate.
64 \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" is a key-value version of Michael's
65 non-intrusive list that is closer to the C++ std library approach.
67 @note Before including <tt><cds/container/michael_list_rcu.h></tt> you should include appropriate RCU header file,
68 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
70 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
71 argument. For example, the following traits-based declaration of Michael's list
74 #include <cds/urcu/general_buffered.h>
75 #include <cds/container/michael_list_rcu.h>
76 // Declare comparator for the item
78 int operator ()( int i1, int i2 )
85 struct my_traits: public cds::container::michael_list::traits
87 typedef my_compare compare;
90 // Declare traits-based list
91 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, my_traits > traits_based_list;
94 is equivalent for the following option-based list
96 #include <cds/urcu/general_buffered.h>
97 #include <cds/container/michael_list_rcu.h>
99 // my_compare is the same
101 // Declare option-based list
102 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int,
103 typename cds::container::michael_list::make_traits<
104 cds::container::opt::compare< my_compare > // item comparator option
109 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
110 - opt::compare - key comparison functor. No default functor is provided.
111 If the option is not specified, the opt::less is used.
112 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
113 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
114 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
115 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
116 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
117 or opt::v::sequential_consistent (sequentially consisnent memory model).
118 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
123 #ifdef CDS_DOXYGEN_INVOKED
124 typename Traits = michael_list::traits
129 class MichaelList< cds::urcu::gc<RCU>, T, Traits > :
130 #ifdef CDS_DOXYGEN_INVOKED
131 protected intrusive::MichaelList< cds::urcu::gc<RCU>, T, Traits >
133 protected details::make_michael_list< cds::urcu::gc<RCU>, T, Traits >::type
137 typedef details::make_michael_list< cds::urcu::gc<RCU>, T, Traits > maker;
138 typedef typename maker::type base_class;
142 typedef cds::urcu::gc<RCU> gc; ///< RCU
143 typedef T value_type; ///< Type of value stored in the list
144 typedef Traits traits; ///< List traits
146 typedef typename base_class::back_off back_off; ///< Back-off strategy used
147 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
148 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
149 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
150 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
151 typedef typename base_class::stat stat; ///< Internal statistics
152 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
154 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
155 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
158 // Rebind traits (split-list support)
159 template <typename... Options>
160 struct rebind_traits {
164 , typename cds::opt::make_options< traits, Options...>::type
169 template <typename Stat>
170 using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
175 typedef typename base_class::value_type node_type;
176 typedef typename maker::cxx_allocator cxx_allocator;
177 typedef typename maker::node_deallocator node_deallocator;
178 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
180 typedef typename base_class::atomic_node_ptr head_type;
182 struct node_disposer {
183 void operator()( node_type * pNode )
188 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
193 struct raw_ptr_converter
195 value_type * operator()( node_type * p ) const
197 return p ? &p->m_Value : nullptr;
200 value_type& operator()( node_type& n ) const
205 value_type const& operator()( node_type const& n ) const
213 ///< pointer to extracted node
214 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >;
216 /// Result of \p get(), \p get_with() functions - pointer to the node found
217 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
221 template <bool IsConst>
222 class iterator_type: protected base_class::template iterator_type<IsConst>
224 typedef typename base_class::template iterator_type<IsConst> iterator_base;
226 iterator_type( head_type const& pNode )
227 : iterator_base( pNode )
230 friend class MichaelList;
233 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
234 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
239 iterator_type( iterator_type const& src )
240 : iterator_base( src )
243 value_ptr operator ->() const
245 typename iterator_base::value_ptr p = iterator_base::operator ->();
246 return p ? &(p->m_Value) : nullptr;
249 value_ref operator *() const
251 return (iterator_base::operator *()).m_Value;
255 iterator_type& operator ++()
257 iterator_base::operator ++();
262 bool operator ==(iterator_type<C> const& i ) const
264 return iterator_base::operator ==(i);
267 bool operator !=(iterator_type<C> const& i ) const
269 return iterator_base::operator !=(i);
275 ///@name Forward iterators (only for debugging purpose)
279 You may safely use iterators in multi-threaded environment only under RCU lock.
280 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
282 typedef iterator_type<false> iterator;
284 /// Const forward iterator
285 typedef iterator_type<true> const_iterator;
287 /// Returns a forward iterator addressing the first element in a list
289 For empty list \code begin() == end() \endcode
293 return iterator( head());
296 /// Returns an iterator that addresses the location succeeding the last element in a list
298 Do not use the value returned by <tt>end</tt> function to access any item.
299 Internally, <tt>end</tt> returning value equals to \p nullptr.
301 The returned value can be used only to control reaching the end of the list.
302 For empty list \code begin() == end() \endcode
309 /// Returns a forward const iterator addressing the first element in a list
310 const_iterator begin() const
312 return const_iterator( head());
315 /// Returns a forward const iterator addressing the first element in a list
316 const_iterator cbegin() const
318 return const_iterator( head());
321 /// Returns an const iterator that addresses the location succeeding the last element in a list
322 const_iterator end() const
324 return const_iterator();
327 /// Returns an const iterator that addresses the location succeeding the last element in a list
328 const_iterator cend() const
330 return const_iterator();
335 /// Default constructor
337 Initialize empty list
343 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
344 explicit MichaelList( Stat& st )
360 The function creates a node with copy of \p val value
361 and then inserts the node created into the list.
363 The type \p Q should contain as minimum the complete key of the node.
364 The object of \ref value_type should be constructible from \p val of type \p Q.
365 In trivial case, \p Q is equal to \ref value_type.
367 The function makes RCU lock internally.
369 Returns \p true if inserting successful, \p false otherwise.
371 template <typename Q>
372 bool insert( Q&& val )
374 return insert_at( head(), std::forward<Q>( val ));
379 This function inserts new node with default-constructed value and then it calls
380 \p func functor with signature
381 \code void func( value_type& itemValue ) ;\endcode
383 The argument \p itemValue of user-defined functor \p func is the reference
384 to the list's item inserted. User-defined functor \p func should guarantee that during changing
385 item's value no any other changes could be made on this list's item by concurrent threads.
387 The type \p Q should contain the complete key of the node.
388 The object of \ref value_type should be constructible from \p key of type \p Q.
390 The function allows to split creating of new item into two part:
391 - create item from \p key with initializing key-fields only;
392 - insert new item into the list;
393 - if inserting is successful, initialize non-key fields of item by calling \p f functor
395 This can be useful if complete initialization of object of \p value_type is heavyweight and
396 it is preferable that the initialization should be completed only if inserting is successful.
398 The function makes RCU lock internally.
400 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
402 template <typename Q, typename Func>
403 bool insert( Q&& key, Func func )
405 return insert_at( head(), std::forward<Q>( key ), func );
408 /// Updates data by \p key
410 The operation performs inserting or replacing the element with lock-free manner.
412 If the \p key not found in the list, then the new item created from \p key
413 will be inserted iff \p bAllowInsert is \p true.
414 Otherwise, if \p key is found, the functor \p func is called with item found.
416 The functor \p Func signature is:
419 void operator()( bool bNew, value_type& item, Q const& val );
424 - \p bNew - \p true if the item has been inserted, \p false otherwise
425 - \p item - item of the list
426 - \p val - argument \p key passed into the \p %update() function
428 The functor may change non-key fields of the \p item; however, \p func must guarantee
429 that during changing no any other modifications could be made on this item by concurrent threads.
431 The function applies RCU lock internally.
433 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
434 \p second is true if new item has been added or \p false if the item with \p key
437 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
439 template <typename Q, typename Func>
440 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
442 return update_at( head(), key, func, bAllowInsert );
445 template <typename Q, typename Func>
446 CDS_DEPRECATED("ensure() is deprecated, use update()")
447 std::pair<bool, bool> ensure( Q const& key, Func f )
449 return update( key, f, true );
453 /// Inserts data of type \ref value_type constructed from \p args
455 Returns \p true if inserting successful, \p false otherwise.
457 The function makes RCU lock internally.
459 template <typename... Args>
460 bool emplace( Args&&... args )
462 return emplace_at( head(), std::forward<Args>(args)... );
465 /// Deletes \p key from the list
466 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
467 Since the key of MichaelList's item type \p value_type is not explicitly specified,
468 template parameter \p Q defines the key type searching in the list.
469 The list item comparator should be able to compare values of the type \p value_type
470 and \p Q in any order.
472 RCU \p synchronize method can be called. RCU should not be locked.
474 Return \p true if key is found and deleted, \p false otherwise
476 template <typename Q>
477 bool erase( Q const& key )
479 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
482 /// Deletes the item from the list using \p pred predicate for searching
484 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
485 but \p pred is used for key comparing.
486 \p Less functor has the interface like \p std::less.
487 \p pred must imply the same element order as the comparator used for building the list.
489 template <typename Q, typename Less>
490 bool erase_with( Q const& key, Less pred )
493 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
496 /// Deletes \p key from the list
497 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
498 The function searches an item with key \p key, calls \p f functor with item found
499 and deletes it. If \p key is not found, the functor is not called.
501 The functor \p Func interface:
504 void operator()(const value_type& val) { ... }
508 Since the key of MichaelList's item type \p value_type is not explicitly specified,
509 template parameter \p Q defines the key type searching in the list.
510 The list item comparator should be able to compare the values of type \p value_type
511 and \p Q in any order.
513 RCU \p synchronize method can be called. RCU should not be locked.
515 Return \p true if key is found and deleted, \p false otherwise
517 template <typename Q, typename Func>
518 bool erase( Q const& key, Func f )
520 return erase_at( head(), key, intrusive_key_comparator(), f );
523 /// Deletes the item from the list using \p pred predicate for searching
525 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
526 but \p pred is used for key comparing.
527 \p Less functor has the interface like \p std::less.
528 \p pred must imply the same element order as the comparator used for building the list.
530 template <typename Q, typename Less, typename Func>
531 bool erase_with( Q const& key, Less pred, Func f )
534 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
537 /// Extracts an item from the list
539 @anchor cds_nonintrusive_MichaelList_rcu_extract
540 The function searches an item with key equal to \p key in the list,
541 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
542 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
544 @note The function does NOT dispose the item found. It just excludes the item from the list
545 and returns a pointer to the item.
546 You shouldn't lock RCU for current thread before calling this function.
549 #include <cds/urcu/general_buffered.h>
550 #include <cds/container/michael_list_rcu.h>
552 typedef cds::urcu::gc< general_buffered<> > rcu;
553 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
555 rcu_michael_list theList;
558 rcu_michael_list::exempt_ptr p;
560 // The RCU should NOT be locked when extract() is called!
561 assert( !rcu::is_locked());
564 p = theList.extract( 10 )
566 // do something with p
570 // we may safely release extracted pointer here.
571 // release() passes the pointer to RCU reclamation cycle.
575 template <typename Q>
576 exempt_ptr extract( Q const& key )
578 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator()));
581 /// Extracts an item from the list using \p pred predicate for searching
583 This function is the analog for \p extract(Q const&).
585 The \p pred is a predicate used for key comparing.
586 \p Less has the interface like \p std::less.
587 \p pred must imply the same element order as \ref key_comparator.
589 template <typename Q, typename Less>
590 exempt_ptr extract_with( Q const& key, Less pred )
593 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
596 /// Checks whether the list contains \p key
598 The function searches the item with key equal to \p key
599 and returns \p true if it is found, and \p false otherwise.
601 The function applies RCU lock internally.
603 template <typename Q>
604 bool contains( Q const& key )
606 return find_at( head(), key, intrusive_key_comparator());
609 template <typename Q>
610 CDS_DEPRECATED("deprecated, use contains()")
611 bool find( Q const& key )
613 return contains( key );
617 /// Checks whether the list contains \p key using \p pred predicate for searching
619 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
620 \p Less functor has the interface like \p std::less.
621 \p pred must imply the same element order as the comparator used for building the list.
623 template <typename Q, typename Less>
624 bool contains( Q const& key, Less pred )
627 return find_at( head(), key, typename maker::template less_wrapper<Less>::type());
630 // Deprecatd, use contains()
631 template <typename Q, typename Less>
632 bool find_with( Q const& key, Less pred )
635 return contains( key, pred );
639 /// Finds the key \p key and performs an action with it
640 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
641 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
642 The interface of \p Func functor is:
645 void operator()( value_type& item, Q& key );
648 where \p item is the item found, \p key is the \p %find() function argument.
650 The functor may change non-key fields of \p item. Note that the function is only guarantee
651 that \p item cannot be deleted during functor is executing.
652 The function does not serialize simultaneous access to the list \p item. If such access is
653 possible you must provide your own synchronization schema to exclude unsafe item modifications.
655 The function makes RCU lock internally.
657 The function returns \p true if \p val is found, \p false otherwise.
659 template <typename Q, typename Func>
660 bool find( Q& key, Func f )
662 return find_at( head(), key, intrusive_key_comparator(), f );
665 template <typename Q, typename Func>
666 bool find( Q const& key, Func f )
668 return find_at( head(), key, intrusive_key_comparator(), f );
672 /// Finds the key \p key using \p pred predicate for searching
674 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
675 but \p pred is used for key comparing.
676 \p Less functor has the interface like \p std::less.
677 \p pred must imply the same element order as the comparator used for building the list.
679 template <typename Q, typename Less, typename Func>
680 bool find_with( Q& key, Less pred, Func f )
683 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
686 template <typename Q, typename Less, typename Func>
687 bool find_with( Q const& key, Less pred, Func f )
690 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
694 /// Finds the key \p key and return the item found
695 /** \anchor cds_nonintrusive_MichaelList_rcu_get
696 The function searches the item with key equal to \p key and returns the pointer to item found.
697 If \p key is not found it returns an empty \p raw_ptr.
699 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
701 RCU should be locked before call of this function.
702 Returned item is valid only while RCU is locked:
704 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
707 typename ord_list::raw_ptr rp;
710 ord_list::rcu_lock lock;
712 rp = theList.get( 5 );
717 // Unlock RCU by rcu_lock destructor
718 // A value owned by rp can be freed at any time after RCU has been unlocked
720 // You can manually release rp after RCU-locked section
724 template <typename Q>
725 raw_ptr get( Q const& key )
727 return get_at( head(), key, intrusive_key_comparator());
730 /// Finds \p key and return the item found
732 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
733 but \p pred is used for comparing the keys.
735 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
737 \p pred must imply the same element order as the comparator used for building the list.
739 template <typename Q, typename Less>
740 raw_ptr get_with( Q const& key, Less pred )
743 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
746 /// Checks if the list is empty
749 return base_class::empty();
752 /// Returns list's item count
754 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
755 this function always returns 0.
757 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
758 is empty. To check list emptyness use \p empty() method.
762 return base_class::size();
765 /// Returns const reference to internal statistics
766 stat const& statistics() const
768 return base_class::statistics();
779 bool insert_node( node_type * pNode )
781 return insert_node_at( head(), pNode );
784 bool insert_node_at( head_type& refHead, node_type * pNode )
787 scoped_node_ptr p(pNode);
788 if ( base_class::insert_at( refHead, *pNode )) {
796 template <typename Q>
797 bool insert_at( head_type& refHead, Q&& val )
799 return insert_node_at( refHead, alloc_node( std::forward<Q>( val )));
802 template <typename Q, typename Func>
803 bool insert_at( head_type& refHead, Q&& key, Func f )
805 scoped_node_ptr pNode( alloc_node( std::forward<Q>( key )));
807 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node)); } )) {
814 template <typename... Args>
815 bool emplace_at( head_type& refHead, Args&&... args )
817 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
820 template <typename Q, typename Compare, typename Func>
821 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
823 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node)); } );
826 template <typename Q, typename Func>
827 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
829 scoped_node_ptr pNode( alloc_node( key ));
831 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
832 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
834 if ( ret.first && ret.second )
840 template <typename Q, typename Compare>
841 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
843 return base_class::extract_at( refHead, key, cmp );
846 template <typename Q, typename Compare>
847 bool find_at( head_type& refHead, Q const& key, Compare cmp )
849 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
852 template <typename Q, typename Compare, typename Func>
853 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
855 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
858 template <typename Q, typename Compare>
859 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
861 return raw_ptr( base_class::get_at( refHead, val, cmp ));
864 static value_type& node_to_value( node_type& n )
868 static value_type const& node_to_value( node_type const& n )
873 template <typename Q>
874 static node_type * alloc_node( Q&& v )
876 return cxx_allocator().New( std::forward<Q>( v ));
879 template <typename... Args>
880 static node_type * alloc_node( Args&&... args )
882 return cxx_allocator().MoveNew( std::forward<Args>( args )... );
885 static void free_node( node_type * pNode )
887 cxx_allocator().Delete( pNode );
892 return base_class::m_pHead;
895 head_type& head() const
897 return const_cast<head_type&>(base_class::m_pHead);
902 }} // namespace cds::container
904 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H