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 * get_result;
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 /// Ensures that the \p key exists in the list
389 The operation performs inserting or changing data with lock-free manner.
391 If the \p key not found in the list, then the new item created from \p key
392 is inserted into the list. Otherwise, the functor \p func is called with the item found.
393 The functor \p Func signature is:
396 void operator()( bool bNew, value_type& item, Q const& val );
401 - \p bNew - \p true if the item has been inserted, \p false otherwise
402 - \p item - item of the list
403 - \p val - argument \p key passed into the \p ensure function
405 The functor may change non-key fields of the \p item.
407 The function applies RCU lock internally.
409 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
410 \p second is true if new item has been added or \p false if the item with \p key
411 already is in the list.
413 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
415 template <typename Q, typename Func>
416 std::pair<bool, bool> ensure( Q const& key, Func f )
418 return ensure_at( head(), key, f );
421 /// Deletes \p key from the list
422 /** \anchor cds_nonintrusive_LazyList_rcu_erase
423 Since the key of LazyList's item type \p T is not explicitly specified,
424 template parameter \p Q defines the key type searching in the list.
425 The list item comparator should be able to compare the type \p T of list item
428 RCU \p synchronize method can be called. RCU should not be locked.
430 Return \p true if key is found and deleted, \p false otherwise
432 template <typename Q>
433 bool erase( Q const& key )
435 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
438 /// Deletes the item from the list using \p pred predicate for searching
440 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
441 but \p pred is used for key comparing.
442 \p Less functor has the interface like \p std::less.
443 \p pred must imply the same element order as the comparator used for building the list.
445 template <typename Q, typename Less>
446 bool erase_with( Q const& key, Less pred )
449 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
452 /// Deletes \p key from the list
453 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
454 The function searches an item with key \p key, calls \p f functor
455 and deletes the item. If \p key is not found, the functor is not called.
457 The functor \p Func interface:
460 void operator()(value_type const& val) { ... }
464 Since the key of LazyList's item type \p T is not explicitly specified,
465 template parameter \p Q defines the key type searching in the list.
466 The list item comparator should be able to compare the type \p T of list item
469 RCU \p synchronize method can be called. RCU should not be locked.
471 Return \p true if key is found and deleted, \p false otherwise
473 template <typename Q, typename Func>
474 bool erase( Q const& key, Func f )
476 return erase_at( head(), key, intrusive_key_comparator(), f );
479 /// Deletes the item from the list using \p pred predicate for searching
481 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
482 but \p pred is used for key comparing.
483 \p Less functor has the interface like \p std::less.
484 \p pred must imply the same element order as the comparator used for building the list.
486 template <typename Q, typename Less, typename Func>
487 bool erase_with( Q const& key, Less pred, Func f )
490 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
493 /// Extracts an item from the list
495 @anchor cds_nonintrusive_LazyList_rcu_extract
496 The function searches an item with key equal to \p key in the list,
497 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to an item found.
498 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
500 @note The function does NOT call RCU read-side lock or synchronization,
501 and does NOT dispose the item found. It just excludes the item from the list
502 and returns a pointer to item found.
503 You should lock RCU before calling this function.
506 #include <cds/urcu/general_buffered.h>
507 #include <cds/container/lazy_list_rcu.h>
509 typedef cds::urcu::gc< general_buffered<> > rcu;
510 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
512 rcu_lazy_list theList;
515 rcu_lazy_list::exempt_ptr p;
517 // first, we should lock RCU
518 rcu_lazy_list::rcu_lock sl;
520 // Now, you can apply extract function
521 // Note that you must not delete the item found inside the RCU lock
522 p = theList.extract( 10 );
524 // do something with p
528 // Outside RCU lock section we may safely release extracted pointer.
529 // release() passes the pointer to RCU reclamation cycle.
533 template <typename Q>
534 exempt_ptr extract( Q const& key )
536 return exempt_ptr(extract_at( head(), key, intrusive_key_comparator()));
539 /// Extracts an item from the list using \p pred predicate for searching
541 This function is the analog for \p extract(Q const&).
543 The \p pred is a predicate used for key comparing.
544 \p Less has the interface like \p std::less.
545 \p pred must imply the same element order as \ref key_comparator.
547 template <typename Q, typename Less>
548 exempt_ptr extract_with( Q const& key, Less pred )
551 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
554 /// Finds the key \p key
555 /** \anchor cds_nonintrusive_LazyList_rcu_find_val
556 The function searches the item with key equal to \p key
557 and returns \p true if it is found, and \p false otherwise.
559 The function makes RCU lock internally.
561 template <typename Q>
562 bool find( Q const& key ) const
564 return find_at( head(), key, intrusive_key_comparator() );
567 /// Finds the key \p key using \p pred predicate for searching
569 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_val "find(Q const&)"
570 but \p pred is used for key comparing.
571 \p Less functor has the interface like \p std::less.
572 \p pred must imply the same element order as the comparator used for building the list.
574 template <typename Q, typename Less>
575 bool find_with( Q const& key, Less pred ) const
578 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
581 /// Finds the key \p key and performs an action with it
582 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
583 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
584 The interface of \p Func functor is:
587 void operator()( value_type& item, Q& key );
590 where \p item is the item found, \p key is the \p find() function argument.
592 The functor may change non-key fields of \p item. Note that the function is only guarantee
593 that \p item cannot be deleted during functor is executing.
594 The function does not serialize simultaneous access to the list \p item. If such access is
595 possible you must provide your own synchronization schema to exclude unsafe item modifications.
597 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
598 may modify both arguments.
600 The function makes RCU lock internally.
602 The function returns \p true if \p key is found, \p false otherwise.
604 template <typename Q, typename Func>
605 bool find( Q& key, Func f ) const
607 return find_at( head(), key, intrusive_key_comparator(), f );
610 template <typename Q, typename Func>
611 bool find( Q const& key, Func f ) const
613 return find_at( head(), key, intrusive_key_comparator(), f );
617 /// Finds the key \p key using \p pred predicate for searching
619 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
620 but \p pred is used for key comparing.
621 \p Less functor has the interface like \p std::less.
622 \p pred must imply the same element order as the comparator used for building the list.
624 template <typename Q, typename Less, typename Func>
625 bool find_with( Q& key, Less pred, Func f ) const
628 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
631 template <typename Q, typename Less, typename Func>
632 bool find_with( Q const& key, Less pred, Func f ) const
635 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
639 /// Finds the key \p key and return the item found
640 /** \anchor cds_nonintrusive_LazyList_rcu_get
641 The function searches the item with key equal to \p key and returns the pointer to item found.
642 If \p key is not found it returns \p nullptr.
644 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
646 RCU should be locked before call of this function.
647 Returned item is valid only while RCU is locked:
649 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
654 ord_list::rcu_lock lock;
656 foo * pVal = theList.get( 5 );
661 // Unlock RCU by rcu_lock destructor
662 // pVal can be freed at any time after RCU has been unlocked
666 template <typename Q>
667 value_type * get( Q const& key ) const
669 return get_at( head(), key, intrusive_key_comparator());
672 /// Finds the key \p key and return the item found
674 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
675 but \p pred is used for comparing the keys.
677 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
679 \p pred must imply the same element order as the comparator used for building the list.
681 template <typename Q, typename Less>
682 value_type * get_with( Q const& key, Less pred ) const
685 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
688 /// Checks if the list is empty
691 return base_class::empty();
694 /// Returns list's item count
696 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
697 this function always returns 0.
699 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
700 is empty. To check list emptyness use \ref empty() method.
704 return base_class::size();
715 bool insert_node_at( head_type& refHead, node_type * pNode )
717 assert( pNode != nullptr );
718 scoped_node_ptr p( pNode );
720 if ( base_class::insert_at( &refHead, *pNode )) {
728 template <typename Q>
729 bool insert_at( head_type& refHead, Q const& val )
731 return insert_node_at( refHead, alloc_node( val ));
734 template <typename... Args>
735 bool emplace_at( head_type& refHead, Args&&... args )
737 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
740 template <typename Q, typename Func>
741 bool insert_at( head_type& refHead, Q const& key, Func f )
743 scoped_node_ptr pNode( alloc_node( key ));
745 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
752 template <typename Q, typename Compare, typename Func>
753 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
755 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
758 template <typename Q, typename Compare>
759 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
761 return base_class::extract_at( &refHead, key, cmp );
764 template <typename Q, typename Func>
765 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
767 scoped_node_ptr pNode( alloc_node( key ));
769 std::pair<bool, bool> ret = base_class::ensure_at( &refHead, *pNode,
770 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key ); });
771 if ( ret.first && ret.second )
777 template <typename Q, typename Compare>
778 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
780 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
783 template <typename Q, typename Compare, typename Func>
784 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
786 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
789 template <typename Q, typename Compare>
790 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
792 node_type * pNode = base_class::get_at( &refHead, val, cmp );
793 return pNode ? &pNode->m_Value : nullptr;
799 }} // namespace cds::container
801 #endif // #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H