2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H
32 #define CDSLIB_CONTAINER_LAZY_LIST_RCU_H
35 #include <cds/container/details/lazy_list_base.h>
36 #include <cds/intrusive/lazy_list_rcu.h>
37 #include <cds/details/binary_functor_wrapper.h>
38 #include <cds/container/details/make_lazy_list.h>
40 namespace cds { namespace container {
42 /// Lazy ordered list (template specialization for \ref cds_urcu_desc "RCU")
43 /** @ingroup cds_nonintrusive_list
44 \anchor cds_nonintrusive_LazyList_rcu
46 Usually, ordered single-linked list is used as a building block for the hash table implementation.
47 The complexity of searching is <tt>O(N)</tt>.
50 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
51 "A Lazy Concurrent List-Based Set Algorithm"
53 The lazy list is based on an optimistic locking scheme for inserts and removes,
54 eliminating the need to use the equivalent of an atomically markable
55 reference. It also has a novel wait-free membership \p find operation
56 that does not need to perform cleanup operations and is more efficient.
58 It is non-intrusive version of \p cds::intrusive::LazyList class
61 - \p RCU - one of \ref cds_urcu_gc "RCU type"
62 - \p T - type to be stored in the list.
63 - \p Traits - type traits, default is lazy_list::traits
64 It is possible to declare option-based list with cds::container::lazy_list::make_traits metafunction istead of \p Traits template
65 argument. For example, the following traits-based declaration of \p gc::HP lazy list
67 #include <cds/urcu/general_instant.h>
68 #include <cds/container/lazy_list_rcu.h>
69 // Declare comparator for the item
71 int operator ()( int i1, int i2 )
78 struct my_traits: public cds::container::lazy_list::traits
80 typedef my_compare compare;
83 // Declare traits-based list
84 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int, my_traits > traits_based_list;
86 is equal to the following option-based list
88 #include <cds/urcu/general_instant.h>
89 #include <cds/container/lazy_list_rcu.h>
91 // my_compare is the same
93 // Declare option-based list
94 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_instant<> >, int,
95 typename cds::container::lazy_list::make_traits<
96 cds::container::opt::compare< my_compare > // item comparator option
101 The implementation does not divide type \p T into key and value part and
102 may be used as main building block for some hash set containers.
103 The key is a function (or a part) of type \p T, and this function is specified by \p Traits::compare functor
104 or \p Traits::less predicate
106 \ref cds_nonintrusive_LazyKVList_rcu "LazyKVList" is a key-value version
107 of lazy non-intrusive list that is closer to the C++ std library approach.
109 @note Before including <tt><cds/container/lazy_list_rcu.h></tt> you should include
110 appropriate RCU header file, see \ref cds_urcu_gc "RCU type" for list
111 of existing RCU class and corresponding header files.
116 #ifdef CDS_DOXYGEN_INVOKED
117 typename Traits = lazy_list::traits
122 class LazyList< cds::urcu::gc<RCU>, T, Traits >:
123 #ifdef CDS_DOXYGEN_INVOKED
124 protected intrusive::LazyList< cds::urcu::gc<RCU>, T, Traits >
126 protected details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits >::type
130 typedef details::make_lazy_list< cds::urcu::gc<RCU>, T, Traits > maker;
131 typedef typename maker::type base_class;
135 typedef cds::urcu::gc<RCU> gc; ///< Garbage collector
136 typedef T value_type; ///< Type of value stored in the list
137 typedef Traits traits; ///< List traits
139 typedef typename base_class::back_off back_off; ///< Back-off strategy
140 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
141 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
142 typedef typename maker::key_comparator key_comparator; ///< key compare functor
143 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
144 typedef typename base_class::stat stat; ///< Internal statistics
145 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
147 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
148 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
152 typedef typename base_class::value_type node_type;
153 typedef typename maker::cxx_allocator cxx_allocator;
154 typedef typename maker::node_deallocator node_deallocator;
155 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
157 typedef typename base_class::node_type head_type;
161 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
162 /// Type of \p get() member function return value
163 typedef value_type * raw_ptr;
167 static value_type& node_to_value( node_type& n )
172 static value_type const& node_to_value( node_type const& n )
177 template <typename Q>
178 static node_type * alloc_node( Q const& v )
180 return cxx_allocator().New( v );
183 template <typename... Args>
184 static node_type * alloc_node( Args&&... args )
186 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
189 static void free_node( node_type * pNode )
191 cxx_allocator().Delete( pNode );
194 struct node_disposer {
195 void operator()( node_type * pNode )
200 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
204 return base_class::m_Head;
207 head_type& head() const
209 return const_cast<head_type&>( base_class::m_Head );
214 return base_class::m_Tail;
217 head_type const& tail() const
219 return base_class::m_Tail;
225 template <bool IsConst>
226 class iterator_type: protected base_class::template iterator_type<IsConst>
228 typedef typename base_class::template iterator_type<IsConst> iterator_base;
230 iterator_type( head_type const& pNode )
231 : iterator_base( const_cast<head_type *>( &pNode ))
234 iterator_type( head_type const * pNode )
235 : iterator_base( const_cast<head_type *>( pNode ))
238 friend class LazyList;
241 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
242 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
247 iterator_type( iterator_type const& src )
248 : iterator_base( src )
251 value_ptr operator ->() const
253 typename iterator_base::value_ptr p = iterator_base::operator ->();
254 return p ? &(p->m_Value) : nullptr;
257 value_ref operator *() const
259 return (iterator_base::operator *()).m_Value;
263 iterator_type& operator ++()
265 iterator_base::operator ++();
270 bool operator ==(iterator_type<C> const& i ) const
272 return iterator_base::operator ==(i);
275 bool operator !=(iterator_type<C> const& i ) const
277 return iterator_base::operator !=(i);
283 ///@name Forward iterators (only for debugging purpose)
287 You may safely use iterators in multi-threaded environment only under RCU lock.
288 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
290 typedef iterator_type<false> iterator;
292 /// Const forward iterator
294 For iterator's features and requirements see \ref iterator
296 typedef iterator_type<true> const_iterator;
298 /// Returns a forward iterator addressing the first element in a list
300 For empty list \code begin() == end() \endcode
304 iterator it( head() );
305 ++it ; // skip dummy head node
309 /// Returns an iterator that addresses the location succeeding the last element in a list
311 Do not use the value returned by <tt>end</tt> function to access any item.
313 The returned value can be used only to control reaching the end of the list.
314 For empty list \code begin() == end() \endcode
318 return iterator( tail() );
321 /// Returns a forward const iterator addressing the first element in a list
322 const_iterator begin() const
324 const_iterator it( head() );
325 ++it ; // skip dummy head node
329 /// Returns a forward const iterator addressing the first element in a list
330 const_iterator cbegin() const
332 const_iterator it( head() );
333 ++it ; // skip dummy head node
337 /// Returns an const iterator that addresses the location succeeding the last element in a list
338 const_iterator end() const
340 return const_iterator( tail() );
343 /// Returns an const iterator that addresses the location succeeding the last element in a list
344 const_iterator cend() const
346 return const_iterator( tail() );
351 /// Default constructor
356 template <typename Stat, typename = std::enable_if<std::is_same<stat, lazy_list::wrapped_stat<Stat>>::value >>
357 explicit LazyList( Stat& st )
362 /// Desctructor clears the list
370 The function creates a node with copy of \p val value
371 and then inserts the node created into the list.
373 The type \p Q should contain as minimum the complete key of the node.
374 The object of \p value_type should be constructible from \p val of type \p Q.
375 In trivial case, \p Q is equal to \p value_type.
377 The function makes RCU lock internally.
379 Returns \p true if inserting successful, \p false otherwise.
381 template <typename Q>
382 bool insert( Q const& val )
384 return insert_at( head(), val );
389 This function inserts new node with default-constructed value and then it calls
390 \p func functor with signature
391 \code void func( value_type& itemValue ) ;\endcode
393 The argument \p itemValue of user-defined functor \p func is the reference
394 to the list's item inserted.
395 The user-defined functor is called only if the inserting is success.
397 The type \p Q should contain the complete key of the node.
398 The object of \ref value_type should be constructible from \p key of type \p Q.
400 The function allows to split creating of new item into two part:
401 - create item from \p key with initializing key-fields only;
402 - insert new item into the list;
403 - if inserting is successful, initialize non-key fields of item by calling \p f functor
405 This can be useful if complete initialization of object of \p value_type is heavyweight and
406 it is preferable that the initialization should be completed only if inserting is successful.
408 The function makes RCU lock internally.
410 template <typename Q, typename Func>
411 bool insert( Q const& key, Func func )
413 return insert_at( head(), key, func );
416 /// Inserts data of type \p value_type constructed from \p args
418 Returns \p true if inserting successful, \p false otherwise.
420 The function makes RCU lock internally.
422 template <typename... Args>
423 bool emplace( Args&&... args )
425 return emplace_at( head(), std::forward<Args>(args)... );
428 /// Updates data by \p key
430 The operation performs inserting or replacing the element with lock-free manner.
432 If the \p key not found in the list, then the new item created from \p key
433 will be inserted iff \p bAllowInsert is \p true.
434 Otherwise, if \p key is found, the functor \p func is called with item found.
436 The functor \p Func signature is:
439 void operator()( bool bNew, value_type& item, Q const& val );
444 - \p bNew - \p true if the item has been inserted, \p false otherwise
445 - \p item - item of the list
446 - \p val - argument \p key passed into the \p %update() function
448 The functor may change non-key fields of the \p item;
449 during \p func call \p item is locked so it is safe to modify the item in
450 multi-threaded environment.
452 The function applies RCU lock internally.
454 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
455 \p second is true if new item has been added or \p false if the item with \p key
458 template <typename Q, typename Func>
459 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
461 return update_at( head(), key, func, bAllowInsert );
464 template <typename Q, typename Func>
465 CDS_DEPRECATED("ensure() is deprecated, use update()")
466 std::pair<bool, bool> ensure( Q const& key, Func f )
468 return update( key, f, true );
472 /// Deletes \p key from the list
473 /** \anchor cds_nonintrusive_LazyList_rcu_erase
474 Since the key of LazyList's item type \p T is not explicitly specified,
475 template parameter \p Q defines the key type searching in the list.
476 The list item comparator should be able to compare the type \p T of list item
479 RCU \p synchronize method can be called. RCU should not be locked.
481 Return \p true if key is found and deleted, \p false otherwise
483 template <typename Q>
484 bool erase( Q const& key )
486 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
489 /// Deletes the item from the list using \p pred predicate for searching
491 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase "erase(Q const&)"
492 but \p pred is used for key comparing.
493 \p Less functor has the interface like \p std::less.
494 \p pred must imply the same element order as the comparator used for building the list.
496 template <typename Q, typename Less>
497 bool erase_with( Q const& key, Less pred )
500 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
503 /// Deletes \p key from the list
504 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
505 The function searches an item with key \p key, calls \p f functor
506 and deletes the item. If \p key is not found, the functor is not called.
508 The functor \p Func interface:
511 void operator()(value_type const& val) { ... }
515 Since the key of LazyList's item type \p T is not explicitly specified,
516 template parameter \p Q defines the key type searching in the list.
517 The list item comparator should be able to compare the type \p T of list item
520 RCU \p synchronize method can be called. RCU should not be locked.
522 Return \p true if key is found and deleted, \p false otherwise
524 template <typename Q, typename Func>
525 bool erase( Q const& key, Func f )
527 return erase_at( head(), key, intrusive_key_comparator(), f );
530 /// Deletes the item from the list using \p pred predicate for searching
532 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
533 but \p pred is used for key comparing.
534 \p Less functor has the interface like \p std::less.
535 \p pred must imply the same element order as the comparator used for building the list.
537 template <typename Q, typename Less, typename Func>
538 bool erase_with( Q const& key, Less pred, Func f )
541 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
544 /// Extracts an item from the list
546 @anchor cds_nonintrusive_LazyList_rcu_extract
547 The function searches an item with key equal to \p key in the list,
548 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to an item found.
549 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
551 @note The function does NOT call RCU read-side lock or synchronization,
552 and does NOT dispose the item found. It just excludes the item from the list
553 and returns a pointer to item found.
554 You should lock RCU before calling this function.
557 #include <cds/urcu/general_buffered.h>
558 #include <cds/container/lazy_list_rcu.h>
560 typedef cds::urcu::gc< general_buffered<> > rcu;
561 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
563 rcu_lazy_list theList;
566 rcu_lazy_list::exempt_ptr p;
568 // first, we should lock RCU
569 rcu_lazy_list::rcu_lock sl;
571 // Now, you can apply extract function
572 // Note that you must not delete the item found inside the RCU lock
573 p = theList.extract( 10 );
575 // do something with p
579 // Outside RCU lock section we may safely release extracted pointer.
580 // release() passes the pointer to RCU reclamation cycle.
584 template <typename Q>
585 exempt_ptr extract( Q const& key )
587 return exempt_ptr(extract_at( head(), key, intrusive_key_comparator()));
590 /// Extracts an item from the list using \p pred predicate for searching
592 This function is the analog for \p extract(Q const&).
594 The \p pred is a predicate used for key comparing.
595 \p Less has the interface like \p std::less.
596 \p pred must imply the same element order as \ref key_comparator.
598 template <typename Q, typename Less>
599 exempt_ptr extract_with( Q const& key, Less pred )
602 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
605 /// Checks whether the list contains \p key
607 The function searches the item with key equal to \p key
608 and returns \p true if it is found, and \p false otherwise.
610 The function applies RCU lock internally.
612 template <typename Q>
613 bool contains( Q const& key ) const
615 return find_at( head(), key, intrusive_key_comparator() );
618 template <typename Q>
619 CDS_DEPRECATED("deprecated, use contains()")
620 bool find( Q const& key ) const
622 return contains( key );
626 /// Checks whether the list contains \p key using \p pred predicate for searching
628 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
629 \p Less functor has the interface like \p std::less.
630 \p pred must imply the same element order as the comparator used for building the list.
632 template <typename Q, typename Less>
633 bool contains( Q const& key, Less pred ) const
636 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
639 template <typename Q, typename Less>
640 CDS_DEPRECATED("deprecated, use contains()")
641 bool find_with( Q const& key, Less pred ) const
643 return contains( key, pred );
647 /// Finds the key \p key and performs an action with it
648 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
649 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
650 The interface of \p Func functor is:
653 void operator()( value_type& item, Q& key );
656 where \p item is the item found, \p key is the \p find() function argument.
658 The functor may change non-key fields of \p item. Note that the function is only guarantee
659 that \p item cannot be deleted during functor is executing.
660 The function does not serialize simultaneous access to the list \p item. If such access is
661 possible you must provide your own synchronization schema to exclude unsafe item modifications.
663 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
664 may modify both arguments.
666 The function makes RCU lock internally.
668 The function returns \p true if \p key is found, \p false otherwise.
670 template <typename Q, typename Func>
671 bool find( Q& key, Func f ) const
673 return find_at( head(), key, intrusive_key_comparator(), f );
676 template <typename Q, typename Func>
677 bool find( Q const& key, Func f ) const
679 return find_at( head(), key, intrusive_key_comparator(), f );
683 /// Finds the key \p key using \p pred predicate for searching
685 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
686 but \p pred is used for key comparing.
687 \p Less functor has the interface like \p std::less.
688 \p pred must imply the same element order as the comparator used for building the list.
690 template <typename Q, typename Less, typename Func>
691 bool find_with( Q& key, Less pred, Func f ) const
694 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
697 template <typename Q, typename Less, typename Func>
698 bool find_with( Q const& key, Less pred, Func f ) const
701 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
705 /// Finds the key \p key and return the item found
706 /** \anchor cds_nonintrusive_LazyList_rcu_get
707 The function searches the item with key equal to \p key and returns the pointer to item found.
708 If \p key is not found it returns \p nullptr.
710 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
712 RCU should be locked before call of this function.
713 Returned item is valid only while RCU is locked:
715 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
720 ord_list::rcu_lock lock;
722 foo * pVal = theList.get( 5 );
727 // Unlock RCU by rcu_lock destructor
728 // pVal can be freed at any time after RCU has been unlocked
732 template <typename Q>
733 value_type * get( Q const& key ) const
735 return get_at( head(), key, intrusive_key_comparator());
738 /// Finds the key \p key and return the item found
740 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
741 but \p pred is used for comparing the keys.
743 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
745 \p pred must imply the same element order as the comparator used for building the list.
747 template <typename Q, typename Less>
748 value_type * get_with( Q const& key, Less pred ) const
751 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
754 /// Checks if the list is empty
757 return base_class::empty();
760 /// Returns list's item count
762 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
763 this function always returns 0.
765 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
766 is empty. To check list emptyness use \ref empty() method.
770 return base_class::size();
773 /// Returns const reference to internal statistics
774 stat const& statistics() const
776 return base_class::statistics();
787 bool insert_node( node_type * pNode )
789 return insert_node_at( head(), pNode );
792 bool insert_node_at( head_type& refHead, node_type * pNode )
794 assert( pNode != nullptr );
795 scoped_node_ptr p( pNode );
797 if ( base_class::insert_at( &refHead, *pNode )) {
805 template <typename Q>
806 bool insert_at( head_type& refHead, Q const& val )
808 return insert_node_at( refHead, alloc_node( val ));
811 template <typename... Args>
812 bool emplace_at( head_type& refHead, Args&&... args )
814 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
817 template <typename Q, typename Func>
818 bool insert_at( head_type& refHead, Q const& key, Func f )
820 scoped_node_ptr pNode( alloc_node( key ));
822 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
829 template <typename Q, typename Compare, typename Func>
830 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
832 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
835 template <typename Q, typename Compare>
836 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
838 return base_class::extract_at( &refHead, key, cmp );
841 template <typename Q, typename Func>
842 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
844 scoped_node_ptr pNode( alloc_node( key ));
846 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
847 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key );},
849 if ( ret.first && ret.second )
855 template <typename Q, typename Compare>
856 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
858 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
861 template <typename Q, typename Compare, typename Func>
862 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
864 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
867 template <typename Q, typename Compare>
868 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
870 node_type * pNode = base_class::get_at( &refHead, val, cmp );
871 return pNode ? &pNode->m_Value : nullptr;
877 }} // namespace cds::container
879 #endif // #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H