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 template <typename Q, typename Func>
390 bool insert( Q const& key, Func func )
392 return insert_at( head(), key, func );
395 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
397 Returns \p true if inserting successful, \p false otherwise.
399 The function makes RCU lock internally.
401 template <typename... Args>
402 bool emplace( Args&&... args )
404 return emplace_at( head(), std::forward<Args>(args)... );
407 /// Ensures that the \p key exists in the list
409 The operation performs inserting or changing data with lock-free manner.
411 If the \p key not found in the list, then the new item created from \p key
412 is inserted into the list. Otherwise, the functor \p func is called with the item found.
413 The functor \p Func should be a function with signature:
415 void func( bool bNew, value_type& item, Q const& val );
420 void operator()( bool bNew, value_type& item, Q const& val );
425 - \p bNew - \p true if the item has been inserted, \p false otherwise
426 - \p item - item of the list
427 - \p val - argument \p key passed into the \p ensure function
429 The functor may change non-key fields of the \p item; however, \p func must guarantee
430 that during changing no any other modifications could be made on this item by concurrent threads.
432 You may pass \p func argument by reference using \p std::ref
434 The function applies RCU lock internally.
436 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
437 \p second is true if new item has been added or \p false if the item with \p key
438 already is in the list.
440 template <typename Q, typename Func>
441 std::pair<bool, bool> ensure( Q const& key, Func f )
443 return ensure_at( head(), key, f );
446 /// Deletes \p key from the list
447 /** \anchor cds_nonintrusive_LazyList_rcu_erase
448 Since the key of LazyList's item type \p T is not explicitly specified,
449 template parameter \p Q defines the key type searching in the list.
450 The list item comparator should be able to compare the type \p T of list item
453 RCU \p synchronize method can be called. RCU should not be locked.
455 Return \p true if key is found and deleted, \p false otherwise
457 template <typename Q>
458 bool erase( Q const& key )
460 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
463 /// Deletes the item from the list using \p pred predicate for searching
465 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
466 but \p pred is used for key comparing.
467 \p Less functor has the interface like \p std::less.
468 \p pred must imply the same element order as the comparator used for building the list.
470 template <typename Q, typename Less>
471 bool erase_with( Q const& key, Less pred )
473 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
476 /// Deletes \p key from the list
477 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
478 The function searches an item with key \p key, calls \p f functor
479 and deletes the item. If \p key is not found, the functor is not called.
481 The functor \p Func interface:
484 void operator()(value_type const& val) { ... }
487 The functor may be passed by reference with <tt>boost:ref</tt>
489 Since the key of LazyList's item type \p T is not explicitly specified,
490 template parameter \p Q defines the key type searching in the list.
491 The list item comparator should be able to compare the type \p T of list item
494 RCU \p synchronize method can be called. RCU should not be locked.
496 Return \p true if key is found and deleted, \p false otherwise
498 template <typename Q, typename Func>
499 bool erase( Q const& key, Func f )
501 return erase_at( head(), key, intrusive_key_comparator(), f );
504 /// Deletes the item from the list using \p pred predicate for searching
506 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
507 but \p pred is used for key comparing.
508 \p Less functor has the interface like \p std::less.
509 \p pred must imply the same element order as the comparator used for building the list.
511 template <typename Q, typename Less, typename Func>
512 bool erase_with( Q const& key, Less pred, Func f )
514 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
517 /// Extracts an item from the list
519 @anchor cds_nonintrusive_LazyList_rcu_extract
520 The function searches an item with key equal to \p key in the list,
521 unlinks it from the list, and returns pointer to an item found in \p dest argument.
522 If the item with the key equal to \p key is not found the function returns \p false.
524 @note The function does NOT call RCU read-side lock or synchronization,
525 and does NOT dispose the item found. It just excludes the item from the list
526 and returns a pointer to item found.
527 You should lock RCU before calling this function.
530 #include <cds/urcu/general_buffered.h>
531 #include <cds/container/lazy_list_rcu.h>
533 typedef cds::urcu::gc< general_buffered<> > rcu;
534 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
536 rcu_lazy_list theList;
539 rcu_lazy_list::exempt_ptr p;
541 // first, we should lock RCU
542 rcu_lazy_list::rcu_lock sl;
544 // Now, you can apply extract function
545 // Note that you must not delete the item found inside the RCU lock
546 if ( theList.extract( p, 10 )) {
547 // do something with p
551 // Outside RCU lock section we may safely release extracted pointer.
552 // release() passes the pointer to RCU reclamation cycle.
556 template <typename Q>
557 bool extract( exempt_ptr& dest, Q const& key )
559 dest = extract_at( head(), key, intrusive_key_comparator() );
560 return !dest.empty();
563 /// Extracts an item from the list using \p pred predicate for searching
565 This function is the analog for \ref cds_nonintrusive_LazyList_rcu_extract "extract(exempt_ptr&, Q const&)".
567 The \p pred is a predicate used for key comparing.
568 \p Less has the interface like \p std::less.
569 \p pred must imply the same element order as \ref key_comparator.
571 template <typename Q, typename Less>
572 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
574 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
575 return !dest.empty();
578 /// Finds the key \p key
579 /** \anchor cds_nonintrusive_LazyList_rcu_find_val
580 The function searches the item with key equal to \p key
581 and returns \p true if it is found, and \p false otherwise.
583 The function makes RCU lock internally.
585 template <typename Q>
586 bool find( Q const& key ) const
588 return find_at( head(), key, intrusive_key_comparator() );
591 /// Finds the key \p val using \p pred predicate for searching
593 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_val "find(Q const&)"
594 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 find_with( Q const& key, Less pred ) const
601 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
604 /// Finds the key \p val and performs an action with it
605 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
606 The function searches an item with key equal to \p val and calls the functor \p f for the item found.
607 The interface of \p Func functor is:
610 void operator()( value_type& item, Q& val );
613 where \p item is the item found, \p val is the \p find() function argument.
615 You may pass \p f argument by reference using \p std::ref.
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 val 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 val is found, \p false otherwise.
629 template <typename Q, typename Func>
630 bool find( Q& val, Func f ) const
632 return find_at( head(), val, intrusive_key_comparator(), f );
635 /// Finds the key \p val using \p pred predicate for searching
637 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
638 but \p pred is used for key comparing.
639 \p Less functor has the interface like \p std::less.
640 \p pred must imply the same element order as the comparator used for building the list.
642 template <typename Q, typename Less, typename Func>
643 bool find_with( Q& val, Less pred, Func f ) const
645 return find_at( head(), val, typename maker::template less_wrapper<Less>::type(), f );
648 /// Finds the key \p val and performs an action with it
649 /** \anchor cds_nonintrusive_LazyList_rcu_find_cfunc
650 The function searches an item with key equal to \p val and calls the functor \p f for the item found.
651 The interface of \p Func functor is:
654 void operator()( value_type& item, Q const& val );
657 where \p item is the item found, \p val is the <tt>find</tt> function argument.
659 You may pass \p f argument by reference using \p std::ref.
661 The function does not serialize simultaneous access to the list \p item. If such access is
662 possible you must provide your own synchronization schema to exclude unsafe item modifications.
664 The function makes RCU lock internally.
666 The function returns \p true if \p val is found, \p false otherwise.
668 template <typename Q, typename Func>
669 bool find( Q const& val, Func f ) const
671 return find_at( head(), val, intrusive_key_comparator(), f );
674 /// Finds the key \p val using \p pred predicate for searching
676 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_cfunc "find(Q const&, Func)"
677 but \p pred is used for key comparing.
678 \p Less functor has the interface like \p std::less.
679 \p pred must imply the same element order as the comparator used for building the list.
681 template <typename Q, typename Less, typename Func>
682 bool find_with( Q const& val, Less pred, Func f ) const
684 return find_at( head(), val, typename maker::template less_wrapper<Less>::type(), f );
687 /// Finds the key \p val and return the item found
688 /** \anchor cds_nonintrusive_LazyList_rcu_get
689 The function searches the item with key equal to \p val and returns the pointer to item found.
690 If \p val is not found it returns \p nullptr.
692 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
694 RCU should be locked before call of this function.
695 Returned item is valid only while RCU is locked:
697 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
702 ord_list::rcu_lock lock;
704 foo * pVal = theList.get( 5 );
709 // Unlock RCU by rcu_lock destructor
710 // pVal can be freed at any time after RCU has been unlocked
714 template <typename Q>
715 value_type * get( Q const& val ) const
717 return get_at( head(), val, intrusive_key_comparator());
720 /// Finds the key \p val and return the item found
722 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
723 but \p pred is used for comparing the keys.
725 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
727 \p pred must imply the same element order as the comparator used for building the list.
729 template <typename Q, typename Less>
730 value_type * get_with( Q const& val, Less pred ) const
732 return get_at( head(), val, typename maker::template less_wrapper<Less>::type());
735 /// Checks if the list is empty
738 return base_class::empty();
741 /// Returns list's item count
743 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
744 this function always returns 0.
746 <b>Warning</b>: even if you use real item counter and it returns 0, this fact is not mean that the list
747 is empty. To check list emptyness use \ref empty() method.
751 return base_class::size();
756 Post-condition: the list is empty
765 bool insert_node_at( head_type& refHead, node_type * pNode )
767 assert( pNode != nullptr );
768 scoped_node_ptr p( pNode );
770 if ( base_class::insert_at( &refHead, *pNode )) {
778 template <typename Q>
779 bool insert_at( head_type& refHead, Q const& val )
781 return insert_node_at( refHead, alloc_node( val ));
784 template <typename... Args>
785 bool emplace_at( head_type& refHead, Args&&... args )
787 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
790 template <typename Q, typename Func>
791 bool insert_at( head_type& refHead, Q const& key, Func f )
793 scoped_node_ptr pNode( alloc_node( key ));
795 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
802 template <typename Q, typename Compare, typename Func>
803 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
805 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
808 template <typename Q, typename Compare>
809 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
811 return base_class::extract_at( &refHead, key, cmp );
814 template <typename Q, typename Func>
815 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
817 scoped_node_ptr pNode( alloc_node( key ));
819 std::pair<bool, bool> ret = base_class::ensure_at( &refHead, *pNode,
820 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key ); });
821 if ( ret.first && ret.second )
827 template <typename Q, typename Compare>
828 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
830 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
833 template <typename Q, typename Compare, typename Func>
834 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
836 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
839 template <typename Q, typename Compare>
840 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
842 node_type * pNode = base_class::get_at( &refHead, val, cmp );
843 return pNode ? &pNode->m_Value : nullptr;
849 }} // namespace cds::container
851 #endif // #ifndef __CDS_CONTAINER_LAZY_LIST_RCU_H