3 #ifndef __CDS_CONTAINER_LAZY_LIST_RCU_H
4 #define __CDS_CONTAINER_LAZY_LIST_RCU_H
7 #include <cds/container/details/lazy_list_base.h>
8 #include <cds/intrusive/lazy_list_rcu.h>
9 #include <cds/details/binary_functor_wrapper.h>
10 #include <cds/container/details/make_lazy_list.h>
12 namespace cds { namespace container {
14 /// Lazy ordered list (template specialization for \ref cds_urcu_desc "RCU")
15 /** @ingroup cds_nonintrusive_list
16 \anchor cds_nonintrusive_LazyList_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 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
23 "A Lazy Concurrent List-Based Set Algorithm"
25 The lazy list is based on an optimistic locking scheme for inserts and removes,
26 eliminating the need to use the equivalent of an atomically markable
27 reference. It also has a novel wait-free membership \p find operation
28 that does not need to perform cleanup operations and is more efficient.
30 It is non-intrusive version of cds::intrusive::LazyList class
33 - \p RCU - one of \ref cds_urcu_gc "RCU type"
34 - \p T - type stored in the list. The type must be default- and copy-constructible.
35 - \p Traits - type traits, default is lazy_list::type_traits
37 The implementation does not divide type \p T into key and value part and
38 may be used as main building block for hash set containers.
39 The key is a function (or a part) of type \p T, and this function is specified by <tt> Traits::compare </tt> functor
40 or <tt> Traits::less </tt> predicate
42 \ref cds_nonintrusive_LazyKVList_rcu "LazyKVList" is a key-value version
43 of lazy non-intrusive list that is closer to the C++ std library approach.
45 @note Before including <tt><cds/container/lazy_list_rcu.h></tt> you should include
46 appropriate RCU header file, see \ref cds_urcu_gc "RCU type" for list
47 of existing RCU class and corresponding header files.
49 It is possible to declare option-based list with cds::container::lazy_list::make_traits metafunction istead of \p Traits template
50 argument. For example, the following traits-based declaration of gc::HP lazy list
52 #include <cds/urcu/general_instant.h>
53 #include <cds/container/lazy_list_rcu.h>
54 // Declare comparator for the item
56 int operator ()( int i1, int i2 )
62 // Declare type_traits
63 struct my_traits: public cds::container::lazy_list::type_traits
65 typedef my_compare compare;
68 // Declare traits-based list
69 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int, my_traits > traits_based_list;
72 is equivalent for the following option-based list
74 #include <cds/urcu/general_instant.h>
75 #include <cds/container/lazy_list_rcu.h>
77 // my_compare is the same
79 // Declare option-based list
80 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int,
81 typename cds::container::lazy_list::make_traits<
82 cds::container::opt::compare< my_compare > // item comparator option
87 Template argument list \p Options of cds::container::lazy_list::make_traits metafunction are:
88 - opt::lock_type - lock type for per-node locking. Default is cds::lock::Spin. Note that <b>each</b> node
89 of the list has member of type \p lock_type, therefore, heavy-weighted locking primitive is not
90 acceptable as candidate for \p lock_type.
91 - opt::compare - key comparison functor. No default functor is provided.
92 If the option is not specified, the opt::less is used.
93 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
94 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
95 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
96 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
97 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
98 or opt::v::sequential_consistent (sequentially consisnent memory model).
99 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
104 #ifdef CDS_DOXYGEN_INVOKED
105 typename Traits = lazy_list::type_traits
110 class LazyList< cds::urcu::gc<RCU>, T, Traits >:
111 #ifdef CDS_DOXYGEN_INVOKED
112 protected intrusive::LazyList< cds::urcu::gc<RCU>, T, Traits >
114 protected details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits >::type
118 typedef details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits > maker;
119 typedef typename maker::type base_class;
123 typedef T value_type ; ///< Type of value stored in the list
124 typedef typename base_class::gc gc ; ///< Garbage collector used
125 typedef typename base_class::back_off back_off ; ///< Back-off strategy used
126 typedef typename maker::allocator_type allocator_type ; ///< Allocator type used for allocate/deallocate the nodes
127 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
128 typedef typename maker::key_comparator key_comparator ; ///< key compare functor
129 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
130 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< Deadlock checking policy
132 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
133 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
137 typedef typename base_class::value_type node_type;
138 typedef typename maker::cxx_allocator cxx_allocator;
139 typedef typename maker::node_deallocator node_deallocator;
140 typedef typename maker::type_traits::compare intrusive_key_comparator;
142 typedef typename base_class::node_type head_type;
146 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::type_traits::disposer > exempt_ptr; ///< pointer to extracted node
150 static value_type& node_to_value( node_type& n )
154 static value_type const& node_to_value( node_type const& n )
162 template <typename Q>
163 static node_type * alloc_node( Q const& v )
165 return cxx_allocator().New( v );
168 template <typename... Args>
169 static node_type * alloc_node( Args&&... args )
171 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
174 static void free_node( node_type * pNode )
176 cxx_allocator().Delete( pNode );
179 struct node_disposer {
180 void operator()( node_type * pNode )
185 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
189 return base_class::m_Head;
192 head_type& head() const
194 return const_cast<head_type&>( base_class::m_Head );
199 return base_class::m_Tail;
202 head_type const& tail() const
204 return base_class::m_Tail;
210 template <bool IsConst>
211 class iterator_type: protected base_class::template iterator_type<IsConst>
213 typedef typename base_class::template iterator_type<IsConst> iterator_base;
215 iterator_type( head_type const& pNode )
216 : iterator_base( const_cast<head_type *>( &pNode ))
219 iterator_type( head_type const * pNode )
220 : iterator_base( const_cast<head_type *>( pNode ))
223 friend class LazyList;
226 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
227 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
232 iterator_type( iterator_type const& src )
233 : iterator_base( src )
236 value_ptr operator ->() const
238 typename iterator_base::value_ptr p = iterator_base::operator ->();
239 return p ? &(p->m_Value) : nullptr;
242 value_ref operator *() const
244 return (iterator_base::operator *()).m_Value;
248 iterator_type& operator ++()
250 iterator_base::operator ++();
255 bool operator ==(iterator_type<C> const& i ) const
257 return iterator_base::operator ==(i);
260 bool operator !=(iterator_type<C> const& i ) const
262 return iterator_base::operator !=(i);
269 typedef iterator_type<false> iterator;
271 /// Const forward iterator
273 For iterator's features and requirements see \ref iterator
275 typedef iterator_type<true> const_iterator;
277 /// Returns a forward iterator addressing the first element in a list
279 For empty list \code begin() == end() \endcode
283 iterator it( head() );
284 ++it ; // skip dummy head node
288 /// Returns an iterator that addresses the location succeeding the last element in a list
290 Do not use the value returned by <tt>end</tt> function to access any item.
292 The returned value can be used only to control reaching the end of the list.
293 For empty list \code begin() == end() \endcode
297 return iterator( tail() );
300 /// Returns a forward const iterator addressing the first element in a list
302 const_iterator begin() const
304 const_iterator it( head() );
305 ++it ; // skip dummy head node
308 const_iterator cbegin()
310 const_iterator it( head() );
311 ++it ; // skip dummy head node
316 /// Returns an const iterator that addresses the location succeeding the last element in a list
318 const_iterator end() const
320 return const_iterator( tail() );
322 const_iterator cend()
324 return const_iterator( tail() );
329 /// Default constructor
331 Initializes empty list
347 The function creates a node with copy of \p val value
348 and then inserts the node created into the list.
350 The type \p Q should contain as minimum the complete key of the node.
351 The object of \ref value_type should be constructible from \p val of type \p Q.
352 In trivial case, \p Q is equal to \ref value_type.
354 The function makes RCU lock internally.
356 Returns \p true if inserting successful, \p false otherwise.
358 template <typename Q>
359 bool insert( Q const& val )
361 return insert_at( head(), val );
366 This function inserts new node with default-constructed value and then it calls
367 \p func functor with signature
368 \code void func( value_type& itemValue ) ;\endcode
370 The argument \p itemValue of user-defined functor \p func is the reference
371 to the list's item inserted. User-defined functor \p func should guarantee that during changing
372 item's value no any other changes could be made on this list's item by concurrent threads.
373 The user-defined functor can be passed by reference using \p std::ref
374 and it is called only if the inserting is success.
376 The type \p Q should contain the complete key of the node.
377 The object of \ref value_type should be constructible from \p key of type \p Q.
379 The function allows to split creating of new item into two part:
380 - create item from \p key with initializing key-fields only;
381 - insert new item into the list;
382 - if inserting is successful, initialize non-key fields of item by calling \p f functor
384 This can be useful if complete initialization of object of \p value_type is heavyweight and
385 it is preferable that the initialization should be completed only if inserting is successful.
387 The function makes RCU lock internally.
389 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
391 template <typename Q, typename Func>
392 bool insert( Q const& key, Func func )
394 return insert_at( head(), key, func );
397 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
399 Returns \p true if inserting successful, \p false otherwise.
401 The function makes RCU lock internally.
403 template <typename... Args>
404 bool emplace( Args&&... args )
406 return emplace_at( head(), std::forward<Args>(args)... );
409 /// Ensures that the \p key exists in the list
411 The operation performs inserting or changing data with lock-free manner.
413 If the \p key not found in the list, then the new item created from \p key
414 is inserted into the list. Otherwise, the functor \p func is called with the item found.
415 The functor \p Func should be a function with signature:
417 void func( bool bNew, value_type& item, Q const& val );
422 void operator()( bool bNew, value_type& item, Q const& val );
427 - \p bNew - \p true if the item has been inserted, \p false otherwise
428 - \p item - item of the list
429 - \p val - argument \p key passed into the \p ensure function
431 The functor may change non-key fields of the \p item; however, \p func must guarantee
432 that during changing no any other modifications could be made on this item by concurrent threads.
434 You may pass \p func argument by reference using \p std::ref
436 The function applies RCU lock internally.
438 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
439 \p second is true if new item has been added or \p false if the item with \p key
440 already is in the list.
442 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
444 template <typename Q, typename Func>
445 std::pair<bool, bool> ensure( Q const& key, Func f )
447 return ensure_at( head(), key, f );
450 /// Deletes \p key from the list
451 /** \anchor cds_nonintrusive_LazyList_rcu_erase
452 Since the key of LazyList's item type \p T is not explicitly specified,
453 template parameter \p Q defines the key type searching in the list.
454 The list item comparator should be able to compare the type \p T of list item
457 RCU \p synchronize method can be called. RCU should not be locked.
459 Return \p true if key is found and deleted, \p false otherwise
461 template <typename Q>
462 bool erase( Q const& key )
464 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
467 /// Deletes the item from the list using \p pred predicate for searching
469 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
470 but \p pred is used for key comparing.
471 \p Less functor has the interface like \p std::less.
472 \p pred must imply the same element order as the comparator used for building the list.
474 template <typename Q, typename Less>
475 bool erase_with( Q const& key, Less pred )
477 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
480 /// Deletes \p key from the list
481 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
482 The function searches an item with key \p key, calls \p f functor
483 and deletes the item. If \p key is not found, the functor is not called.
485 The functor \p Func interface:
488 void operator()(value_type const& val) { ... }
491 The functor may be passed by reference with <tt>boost:ref</tt>
493 Since the key of LazyList's item type \p T is not explicitly specified,
494 template parameter \p Q defines the key type searching in the list.
495 The list item comparator should be able to compare the type \p T of list item
498 RCU \p synchronize method can be called. RCU should not be locked.
500 Return \p true if key is found and deleted, \p false otherwise
502 template <typename Q, typename Func>
503 bool erase( Q const& key, Func f )
505 return erase_at( head(), key, intrusive_key_comparator(), f );
508 /// Deletes the item from the list using \p pred predicate for searching
510 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
511 but \p pred is used for key comparing.
512 \p Less functor has the interface like \p std::less.
513 \p pred must imply the same element order as the comparator used for building the list.
515 template <typename Q, typename Less, typename Func>
516 bool erase_with( Q const& key, Less pred, Func f )
518 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
521 /// Extracts an item from the list
523 @anchor cds_nonintrusive_LazyList_rcu_extract
524 The function searches an item with key equal to \p key in the list,
525 unlinks it from the list, and returns pointer to an item found in \p dest argument.
526 If the item with the key equal to \p key is not found the function returns \p false.
528 @note The function does NOT call RCU read-side lock or synchronization,
529 and does NOT dispose the item found. It just excludes the item from the list
530 and returns a pointer to item found.
531 You should lock RCU before calling this function.
534 #include <cds/urcu/general_buffered.h>
535 #include <cds/container/lazy_list_rcu.h>
537 typedef cds::urcu::gc< general_buffered<> > rcu;
538 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
540 rcu_lazy_list theList;
543 rcu_lazy_list::exempt_ptr p;
545 // first, we should lock RCU
546 rcu_lazy_list::rcu_lock sl;
548 // Now, you can apply extract function
549 // Note that you must not delete the item found inside the RCU lock
550 if ( theList.extract( p, 10 )) {
551 // do something with p
555 // Outside RCU lock section we may safely release extracted pointer.
556 // release() passes the pointer to RCU reclamation cycle.
560 template <typename Q>
561 bool extract( exempt_ptr& dest, Q const& key )
563 dest = extract_at( head(), key, intrusive_key_comparator() );
564 return !dest.empty();
567 /// Extracts an item from the list using \p pred predicate for searching
569 This function is the analog for \ref cds_nonintrusive_LazyList_rcu_extract "extract(exempt_ptr&, Q const&)".
571 The \p pred is a predicate used for key comparing.
572 \p Less has the interface like \p std::less.
573 \p pred must imply the same element order as \ref key_comparator.
575 template <typename Q, typename Less>
576 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
578 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
579 return !dest.empty();
582 /// Finds the key \p key
583 /** \anchor cds_nonintrusive_LazyList_rcu_find_val
584 The function searches the item with key equal to \p key
585 and returns \p true if it is found, and \p false otherwise.
587 The function makes RCU lock internally.
589 template <typename Q>
590 bool find( Q const& key ) const
592 return find_at( head(), key, intrusive_key_comparator() );
595 /// Finds the key \p val using \p pred predicate for searching
597 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_val "find(Q const&)"
598 but \p pred is used for key comparing.
599 \p Less functor has the interface like \p std::less.
600 \p pred must imply the same element order as the comparator used for building the list.
602 template <typename Q, typename Less>
603 bool find_with( Q const& key, Less pred ) const
605 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
608 /// Finds the key \p val and performs an action with it
609 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
610 The function searches an item with key equal to \p val and calls the functor \p f for the item found.
611 The interface of \p Func functor is:
614 void operator()( value_type& item, Q& val );
617 where \p item is the item found, \p val is the \p find() function argument.
619 You may pass \p f argument by reference using \p std::ref.
621 The functor may change non-key fields of \p item. Note that the function is only guarantee
622 that \p item cannot be deleted during functor is executing.
623 The function does not serialize simultaneous access to the list \p item. If such access is
624 possible you must provide your own synchronization schema to exclude unsafe item modifications.
626 The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor
627 may modify both arguments.
629 The function makes RCU lock internally.
631 The function returns \p true if \p val is found, \p false otherwise.
633 template <typename Q, typename Func>
634 bool find( Q& val, Func f ) const
636 return find_at( head(), val, intrusive_key_comparator(), f );
639 /// Finds the key \p val using \p pred predicate for searching
641 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
642 but \p pred is used for key comparing.
643 \p Less functor has the interface like \p std::less.
644 \p pred must imply the same element order as the comparator used for building the list.
646 template <typename Q, typename Less, typename Func>
647 bool find_with( Q& val, Less pred, Func f ) const
649 return find_at( head(), val, typename maker::template less_wrapper<Less>::type(), f );
652 /// Finds the key \p val and performs an action with it
653 /** \anchor cds_nonintrusive_LazyList_rcu_find_cfunc
654 The function searches an item with key equal to \p val and calls the functor \p f for the item found.
655 The interface of \p Func functor is:
658 void operator()( value_type& item, Q const& val );
661 where \p item is the item found, \p val is the <tt>find</tt> function argument.
663 You may pass \p f argument by reference using \p std::ref.
665 The function does not serialize simultaneous access to the list \p item. If such access is
666 possible you must provide your own synchronization schema to exclude unsafe item modifications.
668 The function makes RCU lock internally.
670 The function returns \p true if \p val is found, \p false otherwise.
672 template <typename Q, typename Func>
673 bool find( Q const& val, Func f ) const
675 return find_at( head(), val, intrusive_key_comparator(), f );
678 /// Finds the key \p val using \p pred predicate for searching
680 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_cfunc "find(Q const&, Func)"
681 but \p pred is used for key comparing.
682 \p Less functor has the interface like \p std::less.
683 \p pred must imply the same element order as the comparator used for building the list.
685 template <typename Q, typename Less, typename Func>
686 bool find_with( Q const& val, Less pred, Func f ) const
688 return find_at( head(), val, typename maker::template less_wrapper<Less>::type(), f );
691 /// Finds the key \p val and return the item found
692 /** \anchor cds_nonintrusive_LazyList_rcu_get
693 The function searches the item with key equal to \p val and returns the pointer to item found.
694 If \p val is not found it returns \p nullptr.
696 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
698 RCU should be locked before call of this function.
699 Returned item is valid only while RCU is locked:
701 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
706 ord_list::rcu_lock lock;
708 foo * pVal = theList.get( 5 );
713 // Unlock RCU by rcu_lock destructor
714 // pVal can be freed at any time after RCU has been unlocked
718 template <typename Q>
719 value_type * get( Q const& val ) const
721 return get_at( head(), val, intrusive_key_comparator());
724 /// Finds the key \p val and return the item found
726 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
727 but \p pred is used for comparing the keys.
729 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
731 \p pred must imply the same element order as the comparator used for building the list.
733 template <typename Q, typename Less>
734 value_type * get_with( Q const& val, Less pred ) const
736 return get_at( head(), val, typename maker::template less_wrapper<Less>::type());
739 /// Checks if the list is empty
742 return base_class::empty();
745 /// Returns list's item count
747 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
748 this function always returns 0.
750 <b>Warning</b>: even if you use real item counter and it returns 0, this fact is not mean that the list
751 is empty. To check list emptyness use \ref empty() method.
755 return base_class::size();
760 Post-condition: the list is empty
769 bool insert_node_at( head_type& refHead, node_type * pNode )
771 assert( pNode != nullptr );
772 scoped_node_ptr p( pNode );
774 if ( base_class::insert_at( &refHead, *pNode )) {
782 template <typename Q>
783 bool insert_at( head_type& refHead, Q const& val )
785 return insert_node_at( refHead, alloc_node( val ));
788 template <typename... Args>
789 bool emplace_at( head_type& refHead, Args&&... args )
791 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
794 template <typename Q, typename Func>
795 bool insert_at( head_type& refHead, Q const& key, Func f )
797 scoped_node_ptr pNode( alloc_node( key ));
799 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
806 template <typename Q, typename Compare, typename Func>
807 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
809 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
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 Func>
819 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
821 scoped_node_ptr pNode( alloc_node( key ));
823 std::pair<bool, bool> ret = base_class::ensure_at( &refHead, *pNode,
824 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key ); });
825 if ( ret.first && ret.second )
831 template <typename Q, typename Compare>
832 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
834 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
837 template <typename Q, typename Compare, typename Func>
838 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
840 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
843 template <typename Q, typename Compare>
844 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
846 node_type * pNode = base_class::get_at( &refHead, val, cmp );
847 return pNode ? &pNode->m_Value : nullptr;
853 }} // namespace cds::container
855 #endif // #ifndef __CDS_CONTAINER_LAZY_LIST_RCU_H