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_LIST_RCU_H
32 #define CDSLIB_CONTAINER_LAZY_LIST_RCU_H
35 #include <cds/container/details/lazy_list_base.h>
36 #include <cds/intrusive/lazy_list_rcu.h>
37 #include <cds/details/binary_functor_wrapper.h>
38 #include <cds/container/details/make_lazy_list.h>
40 namespace cds { namespace container {
42 /// Lazy ordered list (template specialization for \ref cds_urcu_desc "RCU")
43 /** @ingroup cds_nonintrusive_list
44 \anchor cds_nonintrusive_LazyList_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 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
51 "A Lazy Concurrent List-Based Set Algorithm"
53 The lazy list is based on an optimistic locking scheme for inserts and removes,
54 eliminating the need to use the equivalent of an atomically markable
55 reference. It also has a novel wait-free membership \p find operation
56 that does not need to perform cleanup operations and is more efficient.
58 It is non-intrusive version of \p cds::intrusive::LazyList class
61 - \p RCU - one of \ref cds_urcu_gc "RCU type"
62 - \p T - type to be stored in the list.
63 - \p Traits - type traits, default is lazy_list::traits
64 It is possible to declare option-based list with cds::container::lazy_list::make_traits metafunction istead of \p Traits template
65 argument. For example, the following traits-based declaration of \p gc::HP lazy list
67 #include <cds/urcu/general_instant.h>
68 #include <cds/container/lazy_list_rcu.h>
69 // Declare comparator for the item
71 int operator ()( int i1, int i2 )
78 struct my_traits: public cds::container::lazy_list::traits
80 typedef my_compare compare;
83 // Declare traits-based list
84 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int, my_traits > traits_based_list;
86 is equal to the following option-based list
88 #include <cds/urcu/general_instant.h>
89 #include <cds/container/lazy_list_rcu.h>
91 // my_compare is the same
93 // Declare option-based list
94 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int,
95 typename cds::container::lazy_list::make_traits<
96 cds::container::opt::compare< my_compare > // item comparator option
101 The implementation does not divide type \p T into key and value part and
102 may be used as main building block for some hash set containers.
103 The key is a function (or a part) of type \p T, and this function is specified by \p Traits::compare functor
104 or \p Traits::less predicate
106 \ref cds_nonintrusive_LazyKVList_rcu "LazyKVList" is a key-value version
107 of lazy non-intrusive list that is closer to the C++ std library approach.
109 @note Before including <tt><cds/container/lazy_list_rcu.h></tt> you should include
110 appropriate RCU header file, see \ref cds_urcu_gc "RCU type" for list
111 of existing RCU class and corresponding header files.
116 #ifdef CDS_DOXYGEN_INVOKED
117 typename Traits = lazy_list::traits
122 class LazyList< cds::urcu::gc<RCU>, T, Traits >:
123 #ifdef CDS_DOXYGEN_INVOKED
124 protected intrusive::LazyList< cds::urcu::gc<RCU>, T, Traits >
126 protected details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits >::type
130 typedef details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits > maker;
131 typedef typename maker::type base_class;
135 typedef cds::urcu::gc<RCU> gc; ///< Garbage collector
136 typedef T value_type; ///< Type of value stored in the list
137 typedef Traits traits; ///< List traits
139 typedef typename base_class::back_off back_off; ///< Back-off strategy
140 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
141 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
142 typedef typename maker::key_comparator key_comparator; ///< key compare functor
143 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
144 typedef typename base_class::stat stat; ///< Internal statistics
145 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
147 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
148 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
151 // Rebind traits (split-list support)
152 template <typename... Options>
153 struct rebind_traits {
157 , typename cds::opt::make_options< traits, Options...>::type
162 template <typename Stat>
163 using select_stat_wrapper = typename base_class::template select_stat_wrapper< Stat >;
168 typedef typename base_class::value_type node_type;
169 typedef typename maker::cxx_allocator cxx_allocator;
170 typedef typename maker::node_deallocator node_deallocator;
171 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
173 typedef typename base_class::node_type head_type;
175 struct node_disposer {
176 void operator()( node_type * pNode )
181 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
185 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
186 /// Type of \p get() member function return value
187 typedef value_type * raw_ptr;
191 template <bool IsConst>
192 class iterator_type: protected base_class::template iterator_type<IsConst>
194 typedef typename base_class::template iterator_type<IsConst> iterator_base;
196 iterator_type( head_type const& pNode )
197 : iterator_base( const_cast<head_type *>( &pNode ))
200 iterator_type( head_type const * pNode )
201 : iterator_base( const_cast<head_type *>( pNode ))
204 friend class LazyList;
207 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
208 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
213 iterator_type( iterator_type const& src )
214 : iterator_base( src )
217 value_ptr operator ->() const
219 typename iterator_base::value_ptr p = iterator_base::operator ->();
220 return p ? &(p->m_Value) : nullptr;
223 value_ref operator *() const
225 return (iterator_base::operator *()).m_Value;
229 iterator_type& operator ++()
231 iterator_base::operator ++();
236 bool operator ==(iterator_type<C> const& i ) const
238 return iterator_base::operator ==(i);
241 bool operator !=(iterator_type<C> const& i ) const
243 return iterator_base::operator !=(i);
249 ///@name Forward iterators (only for debugging purpose)
253 You may safely use iterators in multi-threaded environment only under RCU lock.
254 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
256 typedef iterator_type<false> iterator;
258 /// Const forward iterator
260 For iterator's features and requirements see \ref iterator
262 typedef iterator_type<true> const_iterator;
264 /// Returns a forward iterator addressing the first element in a list
266 For empty list \code begin() == end() \endcode
270 iterator it( head());
271 ++it ; // skip dummy head node
275 /// Returns an iterator that addresses the location succeeding the last element in a list
277 Do not use the value returned by <tt>end</tt> function to access any item.
279 The returned value can be used only to control reaching the end of the list.
280 For empty list \code begin() == end() \endcode
284 return iterator( tail());
287 /// Returns a forward const iterator addressing the first element in a list
288 const_iterator begin() const
290 const_iterator it( head());
291 ++it ; // skip dummy head node
295 /// Returns a forward const iterator addressing the first element in a list
296 const_iterator cbegin() const
298 const_iterator it( head());
299 ++it ; // skip dummy head node
303 /// Returns an const iterator that addresses the location succeeding the last element in a list
304 const_iterator end() const
306 return const_iterator( tail());
309 /// Returns an const iterator that addresses the location succeeding the last element in a list
310 const_iterator cend() const
312 return const_iterator( tail());
317 /// Default constructor
322 template <typename Stat, typename = std::enable_if<std::is_same<stat, lazy_list::wrapped_stat<Stat>>::value >>
323 explicit LazyList( Stat& st )
328 /// Desctructor clears the list
336 The function creates a node with copy of \p val value
337 and then inserts the node created into the list.
339 The type \p Q should contain as minimum the complete key of the node.
340 The object of \p value_type should be constructible from \p val of type \p Q.
341 In trivial case, \p Q is equal to \p value_type.
343 The function makes RCU lock internally.
345 Returns \p true if inserting successful, \p false otherwise.
347 template <typename Q>
348 bool insert( Q&& val )
350 return insert_at( head(), std::forward<Q>( val ));
355 This function inserts new node with default-constructed value and then it calls
356 \p func functor with signature
357 \code void func( value_type& itemValue ) ;\endcode
359 The argument \p itemValue of user-defined functor \p func is the reference
360 to the list's item inserted.
361 The user-defined functor is called only if the inserting is success.
363 The type \p Q should contain the complete key of the node.
364 The object of \ref value_type should be constructible from \p key of type \p Q.
366 The function allows to split creating of new item into two part:
367 - create item from \p key with initializing key-fields only;
368 - insert new item into the list;
369 - if inserting is successful, initialize non-key fields of item by calling \p f functor
371 This can be useful if complete initialization of object of \p value_type is heavyweight and
372 it is preferable that the initialization should be completed only if inserting is successful.
374 The function makes RCU lock internally.
376 template <typename Q, typename Func>
377 bool insert( Q&& key, Func func )
379 return insert_at( head(), std::forward<Q>( key ), func );
382 /// Inserts data of type \p value_type constructed from \p args
384 Returns \p true if inserting successful, \p false otherwise.
386 The function makes RCU lock internally.
388 template <typename... Args>
389 bool emplace( Args&&... args )
391 return emplace_at( head(), std::forward<Args>(args)... );
394 /// Updates data by \p key
396 The operation performs inserting or replacing the element with lock-free manner.
398 If the \p key not found in the list, then the new item created from \p key
399 will be inserted iff \p bAllowInsert is \p true.
400 Otherwise, if \p key is found, the functor \p func is called with item found.
402 The functor \p Func signature is:
405 void operator()( bool bNew, value_type& item, Q const& val );
410 - \p bNew - \p true if the item has been inserted, \p false otherwise
411 - \p item - item of the list
412 - \p val - argument \p key passed into the \p %update() function
414 The functor may change non-key fields of the \p item;
415 during \p func call \p item is locked so it is safe to modify the item in
416 multi-threaded environment.
418 The function applies RCU lock internally.
420 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
421 \p second is true if new item has been added or \p false if the item with \p key
424 template <typename Q, typename Func>
425 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
427 return update_at( head(), key, func, bAllowInsert );
430 template <typename Q, typename Func>
431 CDS_DEPRECATED("ensure() is deprecated, use update()")
432 std::pair<bool, bool> ensure( Q const& key, Func f )
434 return update( key, f, true );
438 /// Deletes \p key from the list
439 /** \anchor cds_nonintrusive_LazyList_rcu_erase
440 Since the key of LazyList's item type \p T is not explicitly specified,
441 template parameter \p Q defines the key type searching in the list.
442 The list item comparator should be able to compare the type \p T of list item
445 RCU \p synchronize method can be called. RCU should not be locked.
447 Return \p true if key is found and deleted, \p false otherwise
449 template <typename Q>
450 bool erase( Q const& key )
452 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
455 /// Deletes the item from the list using \p pred predicate for searching
457 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
458 but \p pred is used for key comparing.
459 \p Less functor has the interface like \p std::less.
460 \p pred must imply the same element order as the comparator used for building the list.
462 template <typename Q, typename Less>
463 bool erase_with( Q const& key, Less pred )
466 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
469 /// Deletes \p key from the list
470 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
471 The function searches an item with key \p key, calls \p f functor
472 and deletes the item. If \p key is not found, the functor is not called.
474 The functor \p Func interface:
477 void operator()(value_type const& val) { ... }
481 Since the key of LazyList's item type \p T is not explicitly specified,
482 template parameter \p Q defines the key type searching in the list.
483 The list item comparator should be able to compare the type \p T of list item
486 RCU \p synchronize method can be called. RCU should not be locked.
488 Return \p true if key is found and deleted, \p false otherwise
490 template <typename Q, typename Func>
491 bool erase( Q const& key, Func f )
493 return erase_at( head(), key, intrusive_key_comparator(), f );
496 /// Deletes the item from the list using \p pred predicate for searching
498 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
499 but \p pred is used for key comparing.
500 \p Less functor has the interface like \p std::less.
501 \p pred must imply the same element order as the comparator used for building the list.
503 template <typename Q, typename Less, typename Func>
504 bool erase_with( Q const& key, Less pred, Func f )
507 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
510 /// Extracts an item from the list
512 @anchor cds_nonintrusive_LazyList_rcu_extract
513 The function searches an item with key equal to \p key in the list,
514 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to an item found.
515 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
517 @note The function does NOT call RCU read-side lock or synchronization,
518 and does NOT dispose the item found. It just excludes the item from the list
519 and returns a pointer to item found.
520 You should lock RCU before calling this function.
523 #include <cds/urcu/general_buffered.h>
524 #include <cds/container/lazy_list_rcu.h>
526 typedef cds::urcu::gc< general_buffered<> > rcu;
527 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
529 rcu_lazy_list theList;
532 rcu_lazy_list::exempt_ptr p;
534 // first, we should lock RCU
535 rcu_lazy_list::rcu_lock sl;
537 // Now, you can apply extract function
538 // Note that you must not delete the item found inside the RCU lock
539 p = theList.extract( 10 );
541 // do something with p
545 // Outside RCU lock section we may safely release extracted pointer.
546 // release() passes the pointer to RCU reclamation cycle.
550 template <typename Q>
551 exempt_ptr extract( Q const& key )
553 return exempt_ptr(extract_at( head(), key, intrusive_key_comparator()));
556 /// Extracts an item from the list using \p pred predicate for searching
558 This function is the analog for \p extract(Q const&).
560 The \p pred is a predicate used for key comparing.
561 \p Less has the interface like \p std::less.
562 \p pred must imply the same element order as \ref key_comparator.
564 template <typename Q, typename Less>
565 exempt_ptr extract_with( Q const& key, Less pred )
568 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
571 /// Checks whether the list contains \p key
573 The function searches the item with key equal to \p key
574 and returns \p true if it is found, and \p false otherwise.
576 The function applies RCU lock internally.
578 template <typename Q>
579 bool contains( Q const& key ) const
581 return find_at( head(), key, intrusive_key_comparator());
584 template <typename Q>
585 CDS_DEPRECATED("deprecated, use contains()")
586 bool find( Q const& key ) const
588 return contains( key );
592 /// Checks whether the list contains \p key using \p pred predicate for searching
594 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
595 \p Less functor has the interface like \p std::less.
596 \p pred must imply the same element order as the comparator used for building the list.
598 template <typename Q, typename Less>
599 bool contains( Q const& key, Less pred ) const
602 return find_at( head(), key, typename maker::template less_wrapper<Less>::type());
605 template <typename Q, typename Less>
606 CDS_DEPRECATED("deprecated, use contains()")
607 bool find_with( Q const& key, Less pred ) const
609 return contains( key, pred );
613 /// Finds the key \p key and performs an action with it
614 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
615 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
616 The interface of \p Func functor is:
619 void operator()( value_type& item, Q& key );
622 where \p item is the item found, \p key is the \p find() function argument.
624 The functor may change non-key fields of \p item. Note that the function is only guarantee
625 that \p item cannot be deleted during functor is executing.
626 The function does not serialize simultaneous access to the list \p item. If such access is
627 possible you must provide your own synchronization schema to exclude unsafe item modifications.
629 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
630 may modify both arguments.
632 The function makes RCU lock internally.
634 The function returns \p true if \p key is found, \p false otherwise.
636 template <typename Q, typename Func>
637 bool find( Q& key, Func f ) const
639 return find_at( head(), key, intrusive_key_comparator(), f );
642 template <typename Q, typename Func>
643 bool find( Q const& key, Func f ) const
645 return find_at( head(), key, intrusive_key_comparator(), f );
649 /// Finds the key \p key using \p pred predicate for searching
651 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
652 but \p pred is used for key comparing.
653 \p Less functor has the interface like \p std::less.
654 \p pred must imply the same element order as the comparator used for building the list.
656 template <typename Q, typename Less, typename Func>
657 bool find_with( Q& key, Less pred, Func f ) const
660 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
663 template <typename Q, typename Less, typename Func>
664 bool find_with( Q const& key, Less pred, Func f ) const
667 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
671 /// Finds the key \p key and return the item found
672 /** \anchor cds_nonintrusive_LazyList_rcu_get
673 The function searches the item with key equal to \p key and returns the pointer to item found.
674 If \p key is not found it returns \p nullptr.
676 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
678 RCU should be locked before call of this function.
679 Returned item is valid only while RCU is locked:
681 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
686 ord_list::rcu_lock lock;
688 foo * pVal = theList.get( 5 );
693 // Unlock RCU by rcu_lock destructor
694 // pVal can be freed at any time after RCU has been unlocked
698 template <typename Q>
699 value_type * get( Q const& key ) const
701 return get_at( head(), key, intrusive_key_comparator());
704 /// Finds the key \p key and return the item found
706 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
707 but \p pred is used for comparing the keys.
709 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
711 \p pred must imply the same element order as the comparator used for building the list.
713 template <typename Q, typename Less>
714 value_type * get_with( Q const& key, Less pred ) const
717 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
720 /// Checks if the list is empty
723 return base_class::empty();
726 /// Returns list's item count
728 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
729 this function always returns 0.
731 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
732 is empty. To check list emptyness use \ref empty() method.
736 return base_class::size();
739 /// Returns const reference to internal statistics
740 stat const& statistics() const
742 return base_class::statistics();
753 bool insert_node( node_type * pNode )
755 return insert_node_at( head(), pNode );
758 bool insert_node_at( head_type& refHead, node_type * pNode )
760 assert( pNode != nullptr );
761 scoped_node_ptr p( pNode );
763 if ( base_class::insert_at( &refHead, *pNode )) {
771 template <typename Q>
772 bool insert_at( head_type& refHead, Q&& val )
774 return insert_node_at( refHead, alloc_node( std::forward<Q>( val )));
777 template <typename... Args>
778 bool emplace_at( head_type& refHead, Args&&... args )
780 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
783 template <typename Q, typename Func>
784 bool insert_at( head_type& refHead, Q&& key, Func f )
786 scoped_node_ptr pNode( alloc_node( std::forward<Q>( key )));
788 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node)); } )) {
795 template <typename Q, typename Compare, typename Func>
796 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
798 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node)); } );
801 template <typename Q, typename Compare>
802 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
804 return base_class::extract_at( &refHead, key, cmp );
807 template <typename Q, typename Func>
808 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
810 scoped_node_ptr pNode( alloc_node( key ));
812 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
813 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key );},
815 if ( ret.first && ret.second )
821 template <typename Q, typename Compare>
822 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
824 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
827 template <typename Q, typename Compare, typename Func>
828 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
830 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
833 template <typename Q, typename Compare>
834 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
836 node_type * pNode = base_class::get_at( &refHead, val, cmp );
837 return pNode ? &pNode->m_Value : nullptr;
840 static value_type& node_to_value( node_type& n )
845 static value_type const& node_to_value( node_type const& n )
850 template <typename Q>
851 static node_type * alloc_node( Q&& v )
853 return cxx_allocator().New( std::forward<Q>( v ));
856 template <typename... Args>
857 static node_type * alloc_node( Args&&... args )
859 return cxx_allocator().MoveNew( std::forward<Args>( args )... );
862 static void free_node( node_type * pNode )
864 cxx_allocator().Delete( pNode );
869 return base_class::m_Head;
872 head_type& head() const
874 return const_cast<head_type&>(base_class::m_Head);
879 return base_class::m_Tail;
882 head_type const& tail() const
884 return base_class::m_Tail;
889 }} // namespace cds::container
891 #endif // #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H