3 #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H
4 #define CDSLIB_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 \p cds::intrusive::LazyList class
33 - \p RCU - one of \ref cds_urcu_gc "RCU type"
34 - \p T - type to be stored in the list.
35 - \p Traits - type traits, default is lazy_list::traits
36 It is possible to declare option-based list with cds::container::lazy_list::make_traits metafunction istead of \p Traits template
37 argument. For example, the following traits-based declaration of \p gc::HP lazy list
39 #include <cds/urcu/general_instant.h>
40 #include <cds/container/lazy_list_rcu.h>
41 // Declare comparator for the item
43 int operator ()( int i1, int i2 )
50 struct my_traits: public cds::container::lazy_list::traits
52 typedef my_compare compare;
55 // Declare traits-based list
56 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int, my_traits > traits_based_list;
58 is equal to the following option-based list
60 #include <cds/urcu/general_instant.h>
61 #include <cds/container/lazy_list_rcu.h>
63 // my_compare is the same
65 // Declare option-based list
66 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int,
67 typename cds::container::lazy_list::make_traits<
68 cds::container::opt::compare< my_compare > // item comparator option
73 The implementation does not divide type \p T into key and value part and
74 may be used as main building block for some hash set containers.
75 The key is a function (or a part) of type \p T, and this function is specified by \p Traits::compare functor
76 or \p Traits::less predicate
78 \ref cds_nonintrusive_LazyKVList_rcu "LazyKVList" is a key-value version
79 of lazy non-intrusive list that is closer to the C++ std library approach.
81 @note Before including <tt><cds/container/lazy_list_rcu.h></tt> you should include
82 appropriate RCU header file, see \ref cds_urcu_gc "RCU type" for list
83 of existing RCU class and corresponding header files.
88 #ifdef CDS_DOXYGEN_INVOKED
89 typename Traits = lazy_list::traits
94 class LazyList< cds::urcu::gc<RCU>, T, Traits >:
95 #ifdef CDS_DOXYGEN_INVOKED
96 protected intrusive::LazyList< cds::urcu::gc<RCU>, T, Traits >
98 protected details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits >::type
102 typedef details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits > maker;
103 typedef typename maker::type base_class;
107 typedef cds::urcu::gc<RCU> gc; ///< Garbage collector
108 typedef T value_type; ///< Type of value stored in the list
109 typedef Traits traits; ///< List traits
111 typedef typename base_class::back_off back_off; ///< Back-off strategy
112 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
113 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
114 typedef typename maker::key_comparator key_comparator; ///< key compare functor
115 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
116 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
118 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
119 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
123 typedef typename base_class::value_type node_type;
124 typedef typename maker::cxx_allocator cxx_allocator;
125 typedef typename maker::node_deallocator node_deallocator;
126 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
128 typedef typename base_class::node_type head_type;
132 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
133 /// Type of \p get() member function return value
134 typedef value_type * raw_ptr;
138 static value_type& node_to_value( node_type& n )
142 static value_type const& node_to_value( node_type const& n )
150 template <typename Q>
151 static node_type * alloc_node( Q const& v )
153 return cxx_allocator().New( v );
156 template <typename... Args>
157 static node_type * alloc_node( Args&&... args )
159 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
162 static void free_node( node_type * pNode )
164 cxx_allocator().Delete( pNode );
167 struct node_disposer {
168 void operator()( node_type * pNode )
173 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
177 return base_class::m_Head;
180 head_type& head() const
182 return const_cast<head_type&>( base_class::m_Head );
187 return base_class::m_Tail;
190 head_type const& tail() const
192 return base_class::m_Tail;
198 template <bool IsConst>
199 class iterator_type: protected base_class::template iterator_type<IsConst>
201 typedef typename base_class::template iterator_type<IsConst> iterator_base;
203 iterator_type( head_type const& pNode )
204 : iterator_base( const_cast<head_type *>( &pNode ))
207 iterator_type( head_type const * pNode )
208 : iterator_base( const_cast<head_type *>( pNode ))
211 friend class LazyList;
214 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
215 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
220 iterator_type( iterator_type const& src )
221 : iterator_base( src )
224 value_ptr operator ->() const
226 typename iterator_base::value_ptr p = iterator_base::operator ->();
227 return p ? &(p->m_Value) : nullptr;
230 value_ref operator *() const
232 return (iterator_base::operator *()).m_Value;
236 iterator_type& operator ++()
238 iterator_base::operator ++();
243 bool operator ==(iterator_type<C> const& i ) const
245 return iterator_base::operator ==(i);
248 bool operator !=(iterator_type<C> const& i ) const
250 return iterator_base::operator !=(i);
257 typedef iterator_type<false> iterator;
259 /// Const forward iterator
261 For iterator's features and requirements see \ref iterator
263 typedef iterator_type<true> const_iterator;
265 /// Returns a forward iterator addressing the first element in a list
267 For empty list \code begin() == end() \endcode
271 iterator it( head() );
272 ++it ; // skip dummy head node
276 /// Returns an iterator that addresses the location succeeding the last element in a list
278 Do not use the value returned by <tt>end</tt> function to access any item.
280 The returned value can be used only to control reaching the end of the list.
281 For empty list \code begin() == end() \endcode
285 return iterator( tail() );
288 /// Returns a forward const iterator addressing the first element in a list
290 const_iterator begin() const
292 const_iterator it( head() );
293 ++it ; // skip dummy head node
296 const_iterator cbegin() const
298 const_iterator it( head() );
299 ++it ; // skip dummy head node
304 /// Returns an const iterator that addresses the location succeeding the last element in a list
306 const_iterator end() const
308 return const_iterator( tail() );
310 const_iterator cend() const
312 return const_iterator( tail() );
317 /// Default constructor
321 /// Desctructor clears the list
329 The function creates a node with copy of \p val value
330 and then inserts the node created into the list.
332 The type \p Q should contain as minimum the complete key of the node.
333 The object of \p value_type should be constructible from \p val of type \p Q.
334 In trivial case, \p Q is equal to \p value_type.
336 The function makes RCU lock internally.
338 Returns \p true if inserting successful, \p false otherwise.
340 template <typename Q>
341 bool insert( Q const& val )
343 return insert_at( head(), val );
348 This function inserts new node with default-constructed value and then it calls
349 \p func functor with signature
350 \code void func( value_type& itemValue ) ;\endcode
352 The argument \p itemValue of user-defined functor \p func is the reference
353 to the list's item inserted.
354 The user-defined functor is called only if the inserting is success.
356 The type \p Q should contain the complete key of the node.
357 The object of \ref value_type should be constructible from \p key of type \p Q.
359 The function allows to split creating of new item into two part:
360 - create item from \p key with initializing key-fields only;
361 - insert new item into the list;
362 - if inserting is successful, initialize non-key fields of item by calling \p f functor
364 This can be useful if complete initialization of object of \p value_type is heavyweight and
365 it is preferable that the initialization should be completed only if inserting is successful.
367 The function makes RCU lock internally.
369 template <typename Q, typename Func>
370 bool insert( Q const& key, Func func )
372 return insert_at( head(), key, func );
375 /// Inserts data of type \p value_type constructed from \p args
377 Returns \p true if inserting successful, \p false otherwise.
379 The function makes RCU lock internally.
381 template <typename... Args>
382 bool emplace( Args&&... args )
384 return emplace_at( head(), std::forward<Args>(args)... );
387 /// Updates data by \p key
389 The operation performs inserting or replacing the element with lock-free manner.
391 If the \p key not found in the list, then the new item created from \p key
392 will be inserted iff \p bAllowInsert is \p true.
393 Otherwise, if \p key is found, the functor \p func is called with item found.
395 The functor \p Func signature is:
398 void operator()( bool bNew, value_type& item, Q const& val );
403 - \p bNew - \p true if the item has been inserted, \p false otherwise
404 - \p item - item of the list
405 - \p val - argument \p key passed into the \p %update() function
407 The functor may change non-key fields of the \p item;
408 during \p func call \p item is locked so it is safe to modify the item in
409 multi-threaded environment.
411 The function applies RCU lock internally.
413 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
414 \p second is true if new item has been added or \p false if the item with \p key
417 template <typename Q, typename Func>
418 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
420 return update_at( head(), key, func, bAllowInsert );
423 // Deprecated, use update()
424 template <typename Q, typename Func>
425 std::pair<bool, bool> ensure( Q const& key, Func f )
427 return update( key, f, true );
431 /// Deletes \p key from the list
432 /** \anchor cds_nonintrusive_LazyList_rcu_erase
433 Since the key of LazyList's item type \p T is not explicitly specified,
434 template parameter \p Q defines the key type searching in the list.
435 The list item comparator should be able to compare the type \p T of list item
438 RCU \p synchronize method can be called. RCU should not be locked.
440 Return \p true if key is found and deleted, \p false otherwise
442 template <typename Q>
443 bool erase( Q const& key )
445 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
448 /// Deletes the item from the list using \p pred predicate for searching
450 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
451 but \p pred is used for key comparing.
452 \p Less functor has the interface like \p std::less.
453 \p pred must imply the same element order as the comparator used for building the list.
455 template <typename Q, typename Less>
456 bool erase_with( Q const& key, Less pred )
459 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
462 /// Deletes \p key from the list
463 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
464 The function searches an item with key \p key, calls \p f functor
465 and deletes the item. If \p key is not found, the functor is not called.
467 The functor \p Func interface:
470 void operator()(value_type const& val) { ... }
474 Since the key of LazyList's item type \p T is not explicitly specified,
475 template parameter \p Q defines the key type searching in the list.
476 The list item comparator should be able to compare the type \p T of list item
479 RCU \p synchronize method can be called. RCU should not be locked.
481 Return \p true if key is found and deleted, \p false otherwise
483 template <typename Q, typename Func>
484 bool erase( Q const& key, Func f )
486 return erase_at( head(), key, intrusive_key_comparator(), f );
489 /// Deletes the item from the list using \p pred predicate for searching
491 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
492 but \p pred is used for key comparing.
493 \p Less functor has the interface like \p std::less.
494 \p pred must imply the same element order as the comparator used for building the list.
496 template <typename Q, typename Less, typename Func>
497 bool erase_with( Q const& key, Less pred, Func f )
500 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
503 /// Extracts an item from the list
505 @anchor cds_nonintrusive_LazyList_rcu_extract
506 The function searches an item with key equal to \p key in the list,
507 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to an item found.
508 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
510 @note The function does NOT call RCU read-side lock or synchronization,
511 and does NOT dispose the item found. It just excludes the item from the list
512 and returns a pointer to item found.
513 You should lock RCU before calling this function.
516 #include <cds/urcu/general_buffered.h>
517 #include <cds/container/lazy_list_rcu.h>
519 typedef cds::urcu::gc< general_buffered<> > rcu;
520 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
522 rcu_lazy_list theList;
525 rcu_lazy_list::exempt_ptr p;
527 // first, we should lock RCU
528 rcu_lazy_list::rcu_lock sl;
530 // Now, you can apply extract function
531 // Note that you must not delete the item found inside the RCU lock
532 p = theList.extract( 10 );
534 // do something with p
538 // Outside RCU lock section we may safely release extracted pointer.
539 // release() passes the pointer to RCU reclamation cycle.
543 template <typename Q>
544 exempt_ptr extract( Q const& key )
546 return exempt_ptr(extract_at( head(), key, intrusive_key_comparator()));
549 /// Extracts an item from the list using \p pred predicate for searching
551 This function is the analog for \p extract(Q const&).
553 The \p pred is a predicate used for key comparing.
554 \p Less has the interface like \p std::less.
555 \p pred must imply the same element order as \ref key_comparator.
557 template <typename Q, typename Less>
558 exempt_ptr extract_with( Q const& key, Less pred )
561 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
564 /// Checks whether the list contains \p key
566 The function searches the item with key equal to \p key
567 and returns \p true if it is found, and \p false otherwise.
569 The function applies RCU lock internally.
571 template <typename Q>
572 bool contains( Q const& key ) const
574 return find_at( head(), key, intrusive_key_comparator() );
577 // Deprecated, use contains()
578 template <typename Q>
579 bool find( Q const& key ) const
581 return contains( key );
585 /// Checks whether the list contains \p key using \p pred predicate for searching
587 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
588 \p Less functor has the interface like \p std::less.
589 \p pred must imply the same element order as the comparator used for building the list.
591 template <typename Q, typename Less>
592 bool contains( Q const& key, Less pred ) const
595 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
598 // Deprecated, use contains()
599 template <typename Q, typename Less>
600 bool find_with( Q const& key, Less pred ) const
602 return contains( key, pred );
606 /// Finds the key \p key and performs an action with it
607 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
608 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
609 The interface of \p Func functor is:
612 void operator()( value_type& item, Q& key );
615 where \p item is the item found, \p key is the \p find() function argument.
617 The functor may change non-key fields of \p item. Note that the function is only guarantee
618 that \p item cannot be deleted during functor is executing.
619 The function does not serialize simultaneous access to the list \p item. If such access is
620 possible you must provide your own synchronization schema to exclude unsafe item modifications.
622 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
623 may modify both arguments.
625 The function makes RCU lock internally.
627 The function returns \p true if \p key is found, \p false otherwise.
629 template <typename Q, typename Func>
630 bool find( Q& key, Func f ) const
632 return find_at( head(), key, intrusive_key_comparator(), f );
635 template <typename Q, typename Func>
636 bool find( Q const& key, Func f ) const
638 return find_at( head(), key, intrusive_key_comparator(), f );
642 /// Finds the key \p key using \p pred predicate for searching
644 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
645 but \p pred is used for key comparing.
646 \p Less functor has the interface like \p std::less.
647 \p pred must imply the same element order as the comparator used for building the list.
649 template <typename Q, typename Less, typename Func>
650 bool find_with( Q& key, Less pred, Func f ) const
653 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
656 template <typename Q, typename Less, typename Func>
657 bool find_with( Q const& key, Less pred, Func f ) const
660 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
664 /// Finds the key \p key and return the item found
665 /** \anchor cds_nonintrusive_LazyList_rcu_get
666 The function searches the item with key equal to \p key and returns the pointer to item found.
667 If \p key is not found it returns \p nullptr.
669 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
671 RCU should be locked before call of this function.
672 Returned item is valid only while RCU is locked:
674 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
679 ord_list::rcu_lock lock;
681 foo * pVal = theList.get( 5 );
686 // Unlock RCU by rcu_lock destructor
687 // pVal can be freed at any time after RCU has been unlocked
691 template <typename Q>
692 value_type * get( Q const& key ) const
694 return get_at( head(), key, intrusive_key_comparator());
697 /// Finds the key \p key and return the item found
699 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
700 but \p pred is used for comparing the keys.
702 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
704 \p pred must imply the same element order as the comparator used for building the list.
706 template <typename Q, typename Less>
707 value_type * get_with( Q const& key, Less pred ) const
710 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
713 /// Checks if the list is empty
716 return base_class::empty();
719 /// Returns list's item count
721 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
722 this function always returns 0.
724 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
725 is empty. To check list emptyness use \ref empty() method.
729 return base_class::size();
740 bool insert_node_at( head_type& refHead, node_type * pNode )
742 assert( pNode != nullptr );
743 scoped_node_ptr p( pNode );
745 if ( base_class::insert_at( &refHead, *pNode )) {
753 template <typename Q>
754 bool insert_at( head_type& refHead, Q const& val )
756 return insert_node_at( refHead, alloc_node( val ));
759 template <typename... Args>
760 bool emplace_at( head_type& refHead, Args&&... args )
762 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
765 template <typename Q, typename Func>
766 bool insert_at( head_type& refHead, Q const& key, Func f )
768 scoped_node_ptr pNode( alloc_node( key ));
770 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
777 template <typename Q, typename Compare, typename Func>
778 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
780 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
783 template <typename Q, typename Compare>
784 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
786 return base_class::extract_at( &refHead, key, cmp );
789 template <typename Q, typename Func>
790 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
792 scoped_node_ptr pNode( alloc_node( key ));
794 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
795 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key );},
797 if ( ret.first && ret.second )
803 template <typename Q, typename Compare>
804 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
806 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
809 template <typename Q, typename Compare, typename Func>
810 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
812 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
815 template <typename Q, typename Compare>
816 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
818 node_type * pNode = base_class::get_at( &refHead, val, cmp );
819 return pNode ? &pNode->m_Value : nullptr;
825 }} // namespace cds::container
827 #endif // #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H