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_LAZY_KVLIST_RCU_H
32 #define CDSLIB_CONTAINER_LAZY_KVLIST_RCU_H
35 #include <cds/container/details/lazy_list_base.h>
36 #include <cds/intrusive/lazy_list_rcu.h>
37 #include <cds/container/details/make_lazy_kvlist.h>
39 namespace cds { namespace container {
41 /// Lazy ordered list (key-value pair), template specialization for \ref cds_urcu_desc "RCU"
42 /** @ingroup cds_nonintrusive_list
43 \anchor cds_nonintrusive_LazyKVList_rcu
45 This is key-value variation of non-intrusive \p %LazyList.
46 Like standard container, this implementation split a value stored into two part -
47 constant key and alterable value.
49 Usually, ordered single-linked list is used as a building block for the hash table implementation.
50 The complexity of searching is <tt>O(N)</tt>.
53 - \p RCU - one of \ref cds_urcu_gc "RCU type"
54 - \p Key - key type of an item to be stored in the list. It should be copy-constructible
55 - \p Value - value type to be stored in the list
56 - \p Traits - type traits, default is \p lazy_list::traits
57 It is possible to declare option-based list with \p lazy_list::make_traits metafunction istead of \p Traits template
58 argument. For example, the following traits-based declaration of \p gc::HP lazy list
60 #include <cds/urcu/general_threaded.h>
61 #include <cds/container/lazy_kvlist_rcu.h>
62 // Declare comparator for the item
64 int operator ()( int i1, int i2 )
71 struct my_traits: public cds::container::lazy_list::traits
73 typedef my_compare compare;
76 // Declare traits-based list
77 typedef cds::container::LazyKVList< cds::urcu::gc< cds::urcu::general_threaded<> >, int, int, my_traits > traits_based_list;
79 is equal to the following option-based list
81 #include <cds/urcu/general_threaded.h>
82 #include <cds/container/lazy_kvlist_rcu.h>
84 // my_compare is the same
86 // Declare option-based list
87 typedef cds::container::LazyKVList< cds::urcu::gc< cds::urcu::general_threaded<> >, int, int,
88 typename cds::container::lazy_list::make_traits<
89 cds::container::opt::compare< my_compare > // item comparator option
94 @note Before including <tt><cds/container/lazy_kvlist_rcu.h></tt> you should include appropriate RCU header file,
95 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
101 #ifdef CDS_DOXYGEN_INVOKED
102 typename Traits = lazy_list::traits
107 class LazyKVList< cds::urcu::gc<RCU>, Key, Value, Traits >:
108 #ifdef CDS_DOXYGEN_INVOKED
109 protected intrusive::LazyList< cds::urcu::gc<RCU>, implementation_defined, Traits >
111 protected details::make_lazy_kvlist< cds::urcu::gc<RCU>, Key, Value, Traits >::type
115 typedef details::make_lazy_kvlist< cds::urcu::gc<RCU>, Key, Value, Traits > maker;
116 typedef typename maker::type base_class;
120 typedef cds::urcu::gc<RCU> gc; ///< Garbage collector
121 typedef Traits traits; ///< List traits
122 #ifdef CDS_DOXYGEN_INVOKED
123 typedef Key key_type ; ///< Key type
124 typedef Value mapped_type ; ///< Type of value stored in the list
125 typedef std::pair<key_type const, mapped_type> value_type ; ///< key/value pair stored in the list
127 typedef typename maker::key_type key_type;
128 typedef typename maker::mapped_type mapped_type;
129 typedef typename maker::value_type value_type;
131 typedef typename base_class::back_off back_off; ///< Back-off strategy used
132 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
133 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
134 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
135 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
136 typedef typename base_class::stat stat; ///< Internal statistics
137 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
139 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
140 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
143 // Rebind traits (split-list support)
144 template <typename... Options>
145 struct rebind_traits {
148 , key_type, mapped_type
149 , typename cds::opt::make_options< traits, Options...>::type
154 template <typename Stat>
155 using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
160 typedef typename base_class::value_type node_type;
161 typedef typename maker::cxx_allocator cxx_allocator;
162 typedef typename maker::node_deallocator node_deallocator;
163 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
165 typedef typename base_class::node_type head_type;
169 /// pointer to extracted node
170 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer,
171 cds::urcu::details::conventional_exempt_pair_cast<node_type, value_type>
173 /// Type of \p get() member function return value
174 typedef value_type * raw_ptr;
178 template <typename K>
179 static node_type * alloc_node(const K& key)
181 return cxx_allocator().New( key );
184 template <typename K, typename V>
185 static node_type * alloc_node( const K& key, const V& val )
187 return cxx_allocator().New( key, val );
190 template <typename... Args>
191 static node_type * alloc_node( Args&&... args )
193 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
196 static void free_node( node_type * pNode )
198 cxx_allocator().Delete( pNode );
201 struct node_disposer {
202 void operator()( node_type * pNode )
207 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
211 return base_class::m_Head;
214 head_type& head() const
216 return const_cast<head_type&>( base_class::m_Head );
221 return base_class::m_Tail;
224 head_type& tail() const
226 return const_cast<head_type&>( base_class::m_Tail );
233 template <bool IsConst>
234 class iterator_type: protected base_class::template iterator_type<IsConst>
236 typedef typename base_class::template iterator_type<IsConst> iterator_base;
238 iterator_type( head_type const& pNode )
239 : iterator_base( const_cast<head_type *>(&pNode))
241 iterator_type( head_type const * pNode )
242 : iterator_base( const_cast<head_type *>(pNode))
245 friend class LazyKVList;
248 typedef typename cds::details::make_const_type<mapped_type, IsConst>::reference value_ref;
249 typedef typename cds::details::make_const_type<mapped_type, IsConst>::pointer value_ptr;
251 typedef typename cds::details::make_const_type<value_type, IsConst>::reference pair_ref;
252 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer pair_ptr;
257 iterator_type( iterator_type const& src )
258 : iterator_base( src )
261 key_type const& key() const
263 typename iterator_base::value_ptr p = iterator_base::operator ->();
264 assert( p != nullptr );
265 return p->m_Data.first;
268 value_ref val() const
270 typename iterator_base::value_ptr p = iterator_base::operator ->();
271 assert( p != nullptr );
272 return p->m_Data.second;
275 pair_ptr operator ->() const
277 typename iterator_base::value_ptr p = iterator_base::operator ->();
278 return p ? &(p->m_Data) : nullptr;
281 pair_ref operator *() const
283 typename iterator_base::value_ref p = iterator_base::operator *();
288 iterator_type& operator ++()
290 iterator_base::operator ++();
295 bool operator ==(iterator_type<C> const& i ) const
297 return iterator_base::operator ==(i);
300 bool operator !=(iterator_type<C> const& i ) const
302 return iterator_base::operator !=(i);
308 ///@name Forward iterators
312 You may safely use iterators in multi-threaded environment only under external RCU lock.
313 Otherwise, a program crash is possible if another thread deletes the item the iterator points to.
315 typedef iterator_type<false> iterator;
317 /// Const forward iterator
318 typedef iterator_type<true> const_iterator;
320 /// Returns a forward iterator addressing the first element in a list
322 For empty list \code begin() == end() \endcode
326 iterator it( head());
327 ++it ; // skip dummy head
331 /// Returns an iterator that addresses the location succeeding the last element in a list
333 Do not use the value returned by <tt>end</tt> function to access any item.
334 Internally, <tt>end</tt> returning value pointing to dummy tail node.
336 The returned value can be used only to control reaching the end of the list.
337 For empty list \code begin() == end() \endcode
341 return iterator( tail());
344 /// Returns a forward const iterator addressing the first element in a list
345 const_iterator begin() const
347 const_iterator it( head());
348 ++it; // skip dummy head
352 /// Returns a forward const iterator addressing the first element in a list
353 const_iterator cbegin() const
355 const_iterator it( head());
356 ++it; // skip dummy head
360 /// Returns an const iterator that addresses the location succeeding the last element in a list
361 const_iterator end() const
363 return const_iterator( tail());
366 /// Returns an const iterator that addresses the location succeeding the last element in a list
367 const_iterator cend() const
369 return const_iterator( tail());
374 /// Default constructor
379 template <typename Stat, typename = std::enable_if<std::is_same<stat, lazy_list::wrapped_stat<Stat>>::value >>
380 explicit LazyKVList( Stat& st )
385 /// Destructor clears the list
391 /// Inserts new node with key and default value
393 The function creates a node with \p key and default value, and then inserts the node created into the list.
396 - The \ref key_type should be constructible from value of type \p K.
397 In trivial case, \p K is equal to \p key_type.
398 - The \ref mapped_type should be default-constructible.
400 The function makes RCU lock internally.
402 Returns \p true if inserting successful, \p false otherwise.
404 template <typename K>
405 bool insert( const K& key )
407 return insert_at( head(), key );
410 /// Inserts new node with a key and a value
412 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
415 - The \p key_type should be constructible from \p key of type \p K.
416 - The \p mapped_type should be constructible from \p val of type \p V.
418 The function makes RCU lock internally.
420 Returns \p true if inserting successful, \p false otherwise.
422 template <typename K, typename V>
423 bool insert( const K& key, const V& val )
425 return insert_at( head(), key, val );
428 /// Inserts new node and initializes it by a functor
430 This function inserts new node with key \p key and if inserting is successful then it calls
431 \p func functor with signature
434 void operator()( value_type& item );
438 The argument \p item of user-defined functor \p func is the reference
439 to the list's item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
440 The user-defined functor is called only if inserting is successful.
442 The key_type should be constructible from value of type \p K.
444 The function allows to split creating of new item into two part:
445 - create item from \p key;
446 - insert new item into the list;
447 - if inserting is successful, initialize the value of item by calling \p func functor
449 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
450 it is preferable that the initialization should be completed only if inserting is successful.
452 The function makes RCU lock internally.
454 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
456 template <typename K, typename Func>
457 bool insert_with( const K& key, Func func )
459 return insert_with_at( head(), key, func );
462 /// Inserts data of type \p mapped_type constructed from \p args
464 Returns \p true if inserting successful, \p false otherwise.
466 The function makes RCU lock internally.
468 template <typename... Args>
469 bool emplace( Args&&... args )
471 return emplace_at( head(), std::forward<Args>(args)... );
474 /// Updates data by \p key
476 The operation performs inserting or replacing the element with lock-free manner.
478 If the \p key not found in the list, then the new item created from \p key
479 will be inserted iff \p bAllowInsert is \p true.
480 (note that in this case the \ref key_type should be constructible from type \p K).
481 Otherwise, if \p key is found, the functor \p func is called with item found.
483 The functor \p Func signature is:
486 void operator()( bool bNew, value_type& item );
490 - \p bNew - \p true if the item has been inserted, \p false otherwise
491 - \p item - the item found or inserted
493 The functor may change any fields of the \p item.second of \p mapped_type;
494 during \p func call \p item is locked so it is safe to modify the item in
495 multi-threaded environment.
497 The function applies RCU lock internally.
499 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
500 \p second is true if new item has been added or \p false if the item with \p key
503 template <typename K, typename Func>
504 std::pair<bool, bool> update( const K& key, Func func, bool bAllowInsert = true )
506 return update_at( head(), key, func, bAllowInsert );
509 template <typename K, typename Func>
510 CDS_DEPRECATED("ensure() is deprecated, use update()")
511 std::pair<bool, bool> ensure( const K& key, Func f )
513 return update( key, f, true );
517 /// Deletes \p key from the list
518 /** \anchor cds_nonintrusive_LazyKVList_rcu_erase
520 RCU \p synchronize method can be called. RCU should not be locked.
522 Returns \p true if \p key is found and has been deleted, \p false otherwise
524 template <typename K>
525 bool erase( K const& key )
527 return erase_at( head(), key, intrusive_key_comparator());
530 /// Deletes the item from the list using \p pred predicate for searching
532 The function is an analog of \ref cds_nonintrusive_LazyKVList_rcu_erase "erase(K const&)"
533 but \p pred is used for key comparing.
534 \p Less functor has the interface like \p std::less.
535 \p pred must imply the same element order as the comparator used for building the list.
537 template <typename K, typename Less>
538 bool erase_with( K const& key, Less pred )
541 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type());
544 /// Deletes \p key from the list
545 /** \anchor cds_nonintrusive_LazyKVList_rcu_erase_func
546 The function searches an item with key \p key, calls \p f functor
547 and deletes the item. If \p key is not found, the functor is not called.
549 The functor \p Func interface:
552 void operator()(value_type& val) { ... }
556 RCU \p synchronize method can be called. RCU should not be locked.
558 Returns \p true if key is found and deleted, \p false otherwise
560 template <typename K, typename Func>
561 bool erase( K const& key, Func f )
563 return erase_at( head(), key, intrusive_key_comparator(), f );
566 /// Deletes the item from the list using \p pred predicate for searching
568 The function is an analog of \ref cds_nonintrusive_LazyKVList_rcu_erase_func "erase(K const&, Func)"
569 but \p pred is used for key comparing.
570 \p Less functor has the interface like \p std::less.
571 \p pred must imply the same element order as the comparator used for building the list.
573 template <typename K, typename Less, typename Func>
574 bool erase_with( K const& key, Less pred, Func f )
577 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
580 /// Extracts an item from the list
582 @anchor cds_nonintrusive_LazyKVList_rcu_extract
583 The function searches an item with key equal to \p key in the list,
584 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
585 If \p key is not found the function returns an empty \p exempt_ptr.
587 @note The function does NOT call RCU read-side lock or synchronization,
588 and does NOT dispose the item found. It just excludes the item from the list
589 and returns a pointer to item found.
590 You should manually lock RCU before calling this function.
593 #include <cds/urcu/general_buffered.h>
594 #include <cds/container/lazy_kvlist_rcu.h>
596 typedef cds::urcu::gc< general_buffered<> > rcu;
597 typedef cds::container::LazyKVList< rcu, int, Foo > rcu_lazy_list;
599 rcu_lazy_list theList;
602 rcu_lazy_list::exempt_ptr p;
604 // first, we should lock RCU
605 rcu_lazy_list::rcu_lock sl;
607 // Now, you can apply extract function
608 // Note that you must not delete the item found inside the RCU lock
609 p = theList.extract( 10 );
611 // do something with p
615 // Outside RCU lock section we may safely release extracted pointer.
616 // release() passes the pointer to RCU reclamation cycle.
620 template <typename K>
621 exempt_ptr extract( K const& key )
623 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator()));
626 /// Extracts an item from the list using \p pred predicate for searching
628 This function is the analog for \p extract(K const&).
629 The \p pred is a predicate used for key comparing.
630 \p Less has the interface like \p std::less.
631 \p pred must imply the same element order as \ref key_comparator.
633 template <typename K, typename Less>
634 exempt_ptr extract_with( K const& key, Less pred )
637 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
640 /// Checks whether the list contains \p key
642 The function searches the item with key equal to \p key
643 and returns \p true if it is found, and \p false otherwise.
645 The function applies RCU lock internally.
647 template <typename Q>
648 bool contains( Q const& key ) const
650 return find_at( head(), key, intrusive_key_comparator());
653 template <typename Q>
654 CDS_DEPRECATED("deprecated, use contains()")
655 bool find( Q const& key ) const
657 return contains( key );
661 /// Checks whether the map contains \p key using \p pred predicate for searching
663 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
664 \p Less functor has the interface like \p std::less.
665 \p Less must imply the same element order as the comparator used for building the list.
667 The function applies RCU lock internally.
669 template <typename Q, typename Less>
670 bool contains( Q const& key, Less pred ) const
673 return find_at( head(), key, typename maker::template less_wrapper<Less>::type());
676 template <typename Q, typename Less>
677 CDS_DEPRECATED("deprecated, use contains()")
678 bool find_with( Q const& key, Less pred ) const
680 return contains( key, pred );
684 /// Finds the key \p key and performs an action with it
685 /** \anchor cds_nonintrusive_LazyKVList_rcu_find_func
686 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
687 The interface of \p Func functor is:
690 void operator()( value_type& item );
693 where \p item is the item found.
695 The functor may change <tt>item.second</tt> that is reference to value of node.
696 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
697 The function does not serialize simultaneous access to the list \p item. If such access is
698 possible you must provide your own synchronization schema to exclude unsafe item modifications.
700 The function applies RCU lock internally.
702 The function returns \p true if \p key is found, \p false otherwise.
704 template <typename Q, typename Func>
705 bool find( Q const& key, Func f ) const
707 return find_at( head(), key, intrusive_key_comparator(), f );
710 /// Finds the key \p val using \p pred predicate for searching
712 The function is an analog of \ref cds_nonintrusive_LazyKVList_rcu_find_func "find(Q const&, Func)"
713 but \p pred is used for key comparing.
714 \p Less functor has the interface like \p std::less.
715 \p pred must imply the same element order as the comparator used for building the list.
717 template <typename Q, typename Less, typename Func>
718 bool find_with( Q const& key, Less pred, Func f ) const
721 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
724 /// Finds \p key and return the item found
725 /** \anchor cds_nonintrusive_LazyKVList_rcu_get
726 The function searches the item with \p key and returns the pointer to item found.
727 If \p key is not found it returns \p nullptr.
729 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
731 RCU should be locked before call of this function.
732 Returned item is valid only while RCU is locked:
734 typedef cds::container::LazyKVList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, foo, my_traits > ord_list;
739 ord_list::rcu_lock lock;
741 ord_list::value_type * pVal = theList.get( 5 );
746 // Unlock RCU by rcu_lock destructor
747 // pVal can be freed at any time after RCU has been unlocked
751 template <typename K>
752 value_type * get( K const& key ) const
754 return get_at( head(), key, intrusive_key_comparator());
757 /// Finds \p key and return the item found
759 The function is an analog of \ref cds_nonintrusive_LazyKVList_rcu_get "get(K const&)"
760 but \p pred is used for comparing the keys.
762 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
764 \p pred must imply the same element order as the comparator used for building the list.
766 template <typename K, typename Less>
767 value_type * get_with( K const& key, Less pred ) const
770 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
773 /// Checks if the list is empty
776 return base_class::empty();
779 /// Returns list's item count
781 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
782 this function always returns 0.
784 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
785 is empty. To check list emptyness use \ref empty() method.
789 return base_class::size();
792 /// Returns const reference to internal statistics
793 stat const& statistics() const
795 return base_class::statistics();
806 bool insert_node_at( head_type& refHead, node_type * pNode )
808 assert( pNode != nullptr );
809 scoped_node_ptr p( pNode );
811 if ( base_class::insert_at( &refHead, *p )) {
819 template <typename K>
820 bool insert_at( head_type& refHead, const K& key )
822 return insert_node_at( refHead, alloc_node( key ));
825 template <typename K, typename V>
826 bool insert_at( head_type& refHead, const K& key, const V& val )
828 return insert_node_at( refHead, alloc_node( key, val ));
831 template <typename K, typename Func>
832 bool insert_with_at( head_type& refHead, const K& key, Func f )
834 scoped_node_ptr pNode( alloc_node( key ));
836 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node.m_Data ); } )) {
843 template <typename... Args>
844 bool emplace_at( head_type& refHead, Args&&... args )
846 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
849 template <typename K, typename Compare>
850 bool erase_at( head_type& refHead, K const& key, Compare cmp )
852 return base_class::erase_at( &refHead, key, cmp );
855 template <typename K, typename Compare, typename Func>
856 bool erase_at( head_type& refHead, K const & key, Compare cmp, Func f )
858 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const & node){f( const_cast<value_type&>(node.m_Data)); });
861 template <typename K, typename Func>
862 std::pair<bool, bool> update_at( head_type& refHead, const K& key, Func f, bool bAllowInsert )
864 scoped_node_ptr pNode( alloc_node( key ));
866 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
867 [&f]( bool bNew, node_type& node, node_type& ){ f( bNew, node.m_Data ); },
869 if ( ret.first && ret.second )
875 template <typename K, typename Compare>
876 node_type * extract_at( head_type& refHead, K const& key, Compare cmp )
878 return base_class::extract_at( &refHead, key, cmp );
881 template <typename K, typename Compare>
882 bool find_at( head_type& refHead, K const& key, Compare cmp ) const
884 return base_class::find_at( &refHead, key, cmp, [](node_type&, K const&) {} );
887 template <typename K, typename Compare, typename Func>
888 bool find_at( head_type& refHead, K& key, Compare cmp, Func f ) const
890 return base_class::find_at( &refHead, key, cmp, [&f]( node_type& node, K& ){ f( node.m_Data ); });
893 template <typename K, typename Compare>
894 value_type * get_at( head_type& refHead, K const& val, Compare cmp ) const
896 node_type * pNode = base_class::get_at( &refHead, val, cmp );
897 return pNode ? &pNode->m_Data : nullptr;
903 }} // namespace cds::container
905 #endif // #ifndef CDSLIB_CONTAINER_LAZY_KVLIST_RCU_H