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 \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 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer > exempt_ptr; ///< pointer to extracted node
136 static value_type& node_to_value( node_type& n )
140 static value_type const& node_to_value( node_type const& n )
148 template <typename Q>
149 static node_type * alloc_node( Q const& v )
151 return cxx_allocator().New( v );
154 template <typename... Args>
155 static node_type * alloc_node( Args&&... args )
157 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
160 static void free_node( node_type * pNode )
162 cxx_allocator().Delete( pNode );
165 struct node_disposer {
166 void operator()( node_type * pNode )
171 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
175 return base_class::m_Head;
178 head_type& head() const
180 return const_cast<head_type&>( base_class::m_Head );
185 return base_class::m_Tail;
188 head_type const& tail() const
190 return base_class::m_Tail;
196 template <bool IsConst>
197 class iterator_type: protected base_class::template iterator_type<IsConst>
199 typedef typename base_class::template iterator_type<IsConst> iterator_base;
201 iterator_type( head_type const& pNode )
202 : iterator_base( const_cast<head_type *>( &pNode ))
205 iterator_type( head_type const * pNode )
206 : iterator_base( const_cast<head_type *>( pNode ))
209 friend class LazyList;
212 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
213 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
218 iterator_type( iterator_type const& src )
219 : iterator_base( src )
222 value_ptr operator ->() const
224 typename iterator_base::value_ptr p = iterator_base::operator ->();
225 return p ? &(p->m_Value) : nullptr;
228 value_ref operator *() const
230 return (iterator_base::operator *()).m_Value;
234 iterator_type& operator ++()
236 iterator_base::operator ++();
241 bool operator ==(iterator_type<C> const& i ) const
243 return iterator_base::operator ==(i);
246 bool operator !=(iterator_type<C> const& i ) const
248 return iterator_base::operator !=(i);
255 typedef iterator_type<false> iterator;
257 /// Const forward iterator
259 For iterator's features and requirements see \ref iterator
261 typedef iterator_type<true> const_iterator;
263 /// Returns a forward iterator addressing the first element in a list
265 For empty list \code begin() == end() \endcode
269 iterator it( head() );
270 ++it ; // skip dummy head node
274 /// Returns an iterator that addresses the location succeeding the last element in a list
276 Do not use the value returned by <tt>end</tt> function to access any item.
278 The returned value can be used only to control reaching the end of the list.
279 For empty list \code begin() == end() \endcode
283 return iterator( tail() );
286 /// Returns a forward const iterator addressing the first element in a list
288 const_iterator begin() const
290 const_iterator it( head() );
291 ++it ; // skip dummy head node
294 const_iterator cbegin() const
296 const_iterator it( head() );
297 ++it ; // skip dummy head node
302 /// Returns an const iterator that addresses the location succeeding the last element in a list
304 const_iterator end() const
306 return const_iterator( tail() );
308 const_iterator cend() const
310 return const_iterator( tail() );
315 /// Default constructor
319 /// Desctructor clears the list
327 The function creates a node with copy of \p val value
328 and then inserts the node created into the list.
330 The type \p Q should contain as minimum the complete key of the node.
331 The object of \p value_type should be constructible from \p val of type \p Q.
332 In trivial case, \p Q is equal to \p value_type.
334 The function makes RCU lock internally.
336 Returns \p true if inserting successful, \p false otherwise.
338 template <typename Q>
339 bool insert( Q const& val )
341 return insert_at( head(), val );
346 This function inserts new node with default-constructed value and then it calls
347 \p func functor with signature
348 \code void func( value_type& itemValue ) ;\endcode
350 The argument \p itemValue of user-defined functor \p func is the reference
351 to the list's item inserted.
352 The user-defined functor is called only if the inserting is success.
354 The type \p Q should contain the complete key of the node.
355 The object of \ref value_type should be constructible from \p key of type \p Q.
357 The function allows to split creating of new item into two part:
358 - create item from \p key with initializing key-fields only;
359 - insert new item into the list;
360 - if inserting is successful, initialize non-key fields of item by calling \p f functor
362 This can be useful if complete initialization of object of \p value_type is heavyweight and
363 it is preferable that the initialization should be completed only if inserting is successful.
365 The function makes RCU lock internally.
367 template <typename Q, typename Func>
368 bool insert( Q const& key, Func func )
370 return insert_at( head(), key, func );
373 /// Inserts data of type \p value_type constructed from \p args
375 Returns \p true if inserting successful, \p false otherwise.
377 The function makes RCU lock internally.
379 template <typename... Args>
380 bool emplace( Args&&... args )
382 return emplace_at( head(), std::forward<Args>(args)... );
385 /// Ensures that the \p key exists in the list
387 The operation performs inserting or changing data with lock-free manner.
389 If the \p key not found in the list, then the new item created from \p key
390 is inserted into the list. Otherwise, the functor \p func is called with the item found.
391 The functor \p Func signature is:
394 void operator()( bool bNew, value_type& item, Q const& val );
399 - \p bNew - \p true if the item has been inserted, \p false otherwise
400 - \p item - item of the list
401 - \p val - argument \p key passed into the \p ensure function
403 The functor may change non-key fields of the \p item.
405 The function applies RCU lock internally.
407 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
408 \p second is true if new item has been added or \p false if the item with \p key
409 already is in the list.
411 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
413 template <typename Q, typename Func>
414 std::pair<bool, bool> ensure( Q const& key, Func f )
416 return ensure_at( head(), key, f );
419 /// Deletes \p key from the list
420 /** \anchor cds_nonintrusive_LazyList_rcu_erase
421 Since the key of LazyList's item type \p T is not explicitly specified,
422 template parameter \p Q defines the key type searching in the list.
423 The list item comparator should be able to compare the type \p T of list item
426 RCU \p synchronize method can be called. RCU should not be locked.
428 Return \p true if key is found and deleted, \p false otherwise
430 template <typename Q>
431 bool erase( Q const& key )
433 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
436 /// Deletes the item from the list using \p pred predicate for searching
438 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
439 but \p pred is used for key comparing.
440 \p Less functor has the interface like \p std::less.
441 \p pred must imply the same element order as the comparator used for building the list.
443 template <typename Q, typename Less>
444 bool erase_with( Q const& key, Less pred )
446 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
449 /// Deletes \p key from the list
450 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
451 The function searches an item with key \p key, calls \p f functor
452 and deletes the item. If \p key is not found, the functor is not called.
454 The functor \p Func interface:
457 void operator()(value_type const& val) { ... }
461 Since the key of LazyList's item type \p T is not explicitly specified,
462 template parameter \p Q defines the key type searching in the list.
463 The list item comparator should be able to compare the type \p T of list item
466 RCU \p synchronize method can be called. RCU should not be locked.
468 Return \p true if key is found and deleted, \p false otherwise
470 template <typename Q, typename Func>
471 bool erase( Q const& key, Func f )
473 return erase_at( head(), key, intrusive_key_comparator(), f );
476 /// Deletes the item from the list using \p pred predicate for searching
478 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
479 but \p pred is used for key comparing.
480 \p Less functor has the interface like \p std::less.
481 \p pred must imply the same element order as the comparator used for building the list.
483 template <typename Q, typename Less, typename Func>
484 bool erase_with( Q const& key, Less pred, Func f )
486 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
489 /// Extracts an item from the list
491 @anchor cds_nonintrusive_LazyList_rcu_extract
492 The function searches an item with key equal to \p key in the list,
493 unlinks it from the list, and returns pointer to an item found in \p dest argument.
494 If the item with the key equal to \p key is not found the function returns \p false.
496 @note The function does NOT call RCU read-side lock or synchronization,
497 and does NOT dispose the item found. It just excludes the item from the list
498 and returns a pointer to item found.
499 You should lock RCU before calling this function.
502 #include <cds/urcu/general_buffered.h>
503 #include <cds/container/lazy_list_rcu.h>
505 typedef cds::urcu::gc< general_buffered<> > rcu;
506 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
508 rcu_lazy_list theList;
511 rcu_lazy_list::exempt_ptr p;
513 // first, we should lock RCU
514 rcu_lazy_list::rcu_lock sl;
516 // Now, you can apply extract function
517 // Note that you must not delete the item found inside the RCU lock
518 if ( theList.extract( p, 10 )) {
519 // do something with p
523 // Outside RCU lock section we may safely release extracted pointer.
524 // release() passes the pointer to RCU reclamation cycle.
528 template <typename Q>
529 bool extract( exempt_ptr& dest, Q const& key )
531 dest = extract_at( head(), key, intrusive_key_comparator() );
532 return !dest.empty();
535 /// Extracts an item from the list using \p pred predicate for searching
537 This function is the analog for \ref cds_nonintrusive_LazyList_rcu_extract "extract(exempt_ptr&, Q const&)".
539 The \p pred is a predicate used for key comparing.
540 \p Less has the interface like \p std::less.
541 \p pred must imply the same element order as \ref key_comparator.
543 template <typename Q, typename Less>
544 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
546 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
547 return !dest.empty();
550 /// Finds the key \p key
551 /** \anchor cds_nonintrusive_LazyList_rcu_find_val
552 The function searches the item with key equal to \p key
553 and returns \p true if it is found, and \p false otherwise.
555 The function makes RCU lock internally.
557 template <typename Q>
558 bool find( Q const& key ) const
560 return find_at( head(), key, intrusive_key_comparator() );
563 /// Finds the key \p key using \p pred predicate for searching
565 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_val "find(Q const&)"
566 but \p pred is used for key comparing.
567 \p Less functor has the interface like \p std::less.
568 \p pred must imply the same element order as the comparator used for building the list.
570 template <typename Q, typename Less>
571 bool find_with( Q const& key, Less pred ) const
573 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
576 /// Finds the key \p key and performs an action with it
577 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
578 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
579 The interface of \p Func functor is:
582 void operator()( value_type& item, Q& key );
585 where \p item is the item found, \p key is the \p find() function argument.
587 The functor may change non-key fields of \p item. Note that the function is only guarantee
588 that \p item cannot be deleted during functor is executing.
589 The function does not serialize simultaneous access to the list \p item. If such access is
590 possible you must provide your own synchronization schema to exclude unsafe item modifications.
592 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
593 may modify both arguments.
595 The function makes RCU lock internally.
597 The function returns \p true if \p key is found, \p false otherwise.
599 template <typename Q, typename Func>
600 bool find( Q& key, Func f ) const
602 return find_at( head(), key, intrusive_key_comparator(), f );
605 /// Finds the key \p key using \p pred predicate for searching
607 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
608 but \p pred is used for key comparing.
609 \p Less functor has the interface like \p std::less.
610 \p pred must imply the same element order as the comparator used for building the list.
612 template <typename Q, typename Less, typename Func>
613 bool find_with( Q& key, Less pred, Func f ) const
615 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
618 /// Finds the key \p key and return the item found
619 /** \anchor cds_nonintrusive_LazyList_rcu_get
620 The function searches the item with key equal to \p key and returns the pointer to item found.
621 If \p key is not found it returns \p nullptr.
623 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
625 RCU should be locked before call of this function.
626 Returned item is valid only while RCU is locked:
628 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
633 ord_list::rcu_lock lock;
635 foo * pVal = theList.get( 5 );
640 // Unlock RCU by rcu_lock destructor
641 // pVal can be freed at any time after RCU has been unlocked
645 template <typename Q>
646 value_type * get( Q const& key ) const
648 return get_at( head(), key, intrusive_key_comparator());
651 /// Finds the key \p key and return the item found
653 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
654 but \p pred is used for comparing the keys.
656 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
658 \p pred must imply the same element order as the comparator used for building the list.
660 template <typename Q, typename Less>
661 value_type * get_with( Q const& key, Less pred ) const
663 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
666 /// Checks if the list is empty
669 return base_class::empty();
672 /// Returns list's item count
674 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
675 this function always returns 0.
677 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
678 is empty. To check list emptyness use \ref empty() method.
682 return base_class::size();
693 bool insert_node_at( head_type& refHead, node_type * pNode )
695 assert( pNode != nullptr );
696 scoped_node_ptr p( pNode );
698 if ( base_class::insert_at( &refHead, *pNode )) {
706 template <typename Q>
707 bool insert_at( head_type& refHead, Q const& val )
709 return insert_node_at( refHead, alloc_node( val ));
712 template <typename... Args>
713 bool emplace_at( head_type& refHead, Args&&... args )
715 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
718 template <typename Q, typename Func>
719 bool insert_at( head_type& refHead, Q const& key, Func f )
721 scoped_node_ptr pNode( alloc_node( key ));
723 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
730 template <typename Q, typename Compare, typename Func>
731 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
733 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
736 template <typename Q, typename Compare>
737 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
739 return base_class::extract_at( &refHead, key, cmp );
742 template <typename Q, typename Func>
743 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
745 scoped_node_ptr pNode( alloc_node( key ));
747 std::pair<bool, bool> ret = base_class::ensure_at( &refHead, *pNode,
748 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key ); });
749 if ( ret.first && ret.second )
755 template <typename Q, typename Compare>
756 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
758 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
761 template <typename Q, typename Compare, typename Func>
762 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
764 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
767 template <typename Q, typename Compare>
768 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
770 node_type * pNode = base_class::get_at( &refHead, val, cmp );
771 return pNode ? &pNode->m_Value : nullptr;
777 }} // namespace cds::container
779 #endif // #ifndef __CDS_CONTAINER_LAZY_LIST_RCU_H