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) { ... }
460 The functor may be passed by reference with <tt>boost:ref</tt>
462 Since the key of LazyList's item type \p T is not explicitly specified,
463 template parameter \p Q defines the key type searching in the list.
464 The list item comparator should be able to compare the type \p T of list item
467 RCU \p synchronize method can be called. RCU should not be locked.
469 Return \p true if key is found and deleted, \p false otherwise
471 template <typename Q, typename Func>
472 bool erase( Q const& key, Func f )
474 return erase_at( head(), key, intrusive_key_comparator(), f );
477 /// Deletes the item from the list using \p pred predicate for searching
479 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
480 but \p pred is used for key comparing.
481 \p Less functor has the interface like \p std::less.
482 \p pred must imply the same element order as the comparator used for building the list.
484 template <typename Q, typename Less, typename Func>
485 bool erase_with( Q const& key, Less pred, Func f )
487 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
490 /// Extracts an item from the list
492 @anchor cds_nonintrusive_LazyList_rcu_extract
493 The function searches an item with key equal to \p key in the list,
494 unlinks it from the list, and returns pointer to an item found in \p dest argument.
495 If the item with the key equal to \p key is not found the function returns \p false.
497 @note The function does NOT call RCU read-side lock or synchronization,
498 and does NOT dispose the item found. It just excludes the item from the list
499 and returns a pointer to item found.
500 You should lock RCU before calling this function.
503 #include <cds/urcu/general_buffered.h>
504 #include <cds/container/lazy_list_rcu.h>
506 typedef cds::urcu::gc< general_buffered<> > rcu;
507 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
509 rcu_lazy_list theList;
512 rcu_lazy_list::exempt_ptr p;
514 // first, we should lock RCU
515 rcu_lazy_list::rcu_lock sl;
517 // Now, you can apply extract function
518 // Note that you must not delete the item found inside the RCU lock
519 if ( theList.extract( p, 10 )) {
520 // do something with p
524 // Outside RCU lock section we may safely release extracted pointer.
525 // release() passes the pointer to RCU reclamation cycle.
529 template <typename Q>
530 bool extract( exempt_ptr& dest, Q const& key )
532 dest = extract_at( head(), key, intrusive_key_comparator() );
533 return !dest.empty();
536 /// Extracts an item from the list using \p pred predicate for searching
538 This function is the analog for \ref cds_nonintrusive_LazyList_rcu_extract "extract(exempt_ptr&, Q const&)".
540 The \p pred is a predicate used for key comparing.
541 \p Less has the interface like \p std::less.
542 \p pred must imply the same element order as \ref key_comparator.
544 template <typename Q, typename Less>
545 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
547 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
548 return !dest.empty();
551 /// Finds the key \p key
552 /** \anchor cds_nonintrusive_LazyList_rcu_find_val
553 The function searches the item with key equal to \p key
554 and returns \p true if it is found, and \p false otherwise.
556 The function makes RCU lock internally.
558 template <typename Q>
559 bool find( Q const& key ) const
561 return find_at( head(), key, intrusive_key_comparator() );
564 /// Finds the key \p key using \p pred predicate for searching
566 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_val "find(Q const&)"
567 but \p pred is used for key comparing.
568 \p Less functor has the interface like \p std::less.
569 \p pred must imply the same element order as the comparator used for building the list.
571 template <typename Q, typename Less>
572 bool find_with( Q const& key, Less pred ) const
574 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
577 /// Finds the key \p key and performs an action with it
578 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
579 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
580 The interface of \p Func functor is:
583 void operator()( value_type& item, Q& key );
586 where \p item is the item found, \p key is the \p find() function argument.
588 You may pass \p f argument by reference using \p std::ref.
590 The functor may change non-key fields of \p item. Note that the function is only guarantee
591 that \p item cannot be deleted during functor is executing.
592 The function does not serialize simultaneous access to the list \p item. If such access is
593 possible you must provide your own synchronization schema to exclude unsafe item modifications.
595 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
596 may modify both arguments.
598 The function makes RCU lock internally.
600 The function returns \p true if \p key is found, \p false otherwise.
602 template <typename Q, typename Func>
603 bool find( Q& key, Func f ) const
605 return find_at( head(), key, intrusive_key_comparator(), f );
608 /// Finds the key \p key using \p pred predicate for searching
610 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
611 but \p pred is used for key comparing.
612 \p Less functor has the interface like \p std::less.
613 \p pred must imply the same element order as the comparator used for building the list.
615 template <typename Q, typename Less, typename Func>
616 bool find_with( Q& key, Less pred, Func f ) const
618 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
621 /// Finds the key \p key and return the item found
622 /** \anchor cds_nonintrusive_LazyList_rcu_get
623 The function searches the item with key equal to \p key and returns the pointer to item found.
624 If \p key is not found it returns \p nullptr.
626 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
628 RCU should be locked before call of this function.
629 Returned item is valid only while RCU is locked:
631 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
636 ord_list::rcu_lock lock;
638 foo * pVal = theList.get( 5 );
643 // Unlock RCU by rcu_lock destructor
644 // pVal can be freed at any time after RCU has been unlocked
648 template <typename Q>
649 value_type * get( Q const& key ) const
651 return get_at( head(), key, intrusive_key_comparator());
654 /// Finds the key \p key and return the item found
656 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
657 but \p pred is used for comparing the keys.
659 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
661 \p pred must imply the same element order as the comparator used for building the list.
663 template <typename Q, typename Less>
664 value_type * get_with( Q const& key, Less pred ) const
666 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
669 /// Checks if the list is empty
672 return base_class::empty();
675 /// Returns list's item count
677 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
678 this function always returns 0.
680 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
681 is empty. To check list emptyness use \ref empty() method.
685 return base_class::size();
696 bool insert_node_at( head_type& refHead, node_type * pNode )
698 assert( pNode != nullptr );
699 scoped_node_ptr p( pNode );
701 if ( base_class::insert_at( &refHead, *pNode )) {
709 template <typename Q>
710 bool insert_at( head_type& refHead, Q const& val )
712 return insert_node_at( refHead, alloc_node( val ));
715 template <typename... Args>
716 bool emplace_at( head_type& refHead, Args&&... args )
718 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
721 template <typename Q, typename Func>
722 bool insert_at( head_type& refHead, Q const& key, Func f )
724 scoped_node_ptr pNode( alloc_node( key ));
726 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
733 template <typename Q, typename Compare, typename Func>
734 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
736 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
739 template <typename Q, typename Compare>
740 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
742 return base_class::extract_at( &refHead, key, cmp );
745 template <typename Q, typename Func>
746 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
748 scoped_node_ptr pNode( alloc_node( key ));
750 std::pair<bool, bool> ret = base_class::ensure_at( &refHead, *pNode,
751 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key ); });
752 if ( ret.first && ret.second )
758 template <typename Q, typename Compare>
759 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
761 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
764 template <typename Q, typename Compare, typename Func>
765 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
767 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
770 template <typename Q, typename Compare>
771 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
773 node_type * pNode = base_class::get_at( &refHead, val, cmp );
774 return pNode ? &pNode->m_Value : nullptr;
780 }} // namespace cds::container
782 #endif // #ifndef __CDS_CONTAINER_LAZY_LIST_RCU_H