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::rcu_check_deadlock rcu_check_deadlock; ///< Deadlock checking policy
146 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
147 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
151 typedef typename base_class::value_type node_type;
152 typedef typename maker::cxx_allocator cxx_allocator;
153 typedef typename maker::node_deallocator node_deallocator;
154 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
156 typedef typename base_class::node_type head_type;
160 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
161 /// Type of \p get() member function return value
162 typedef value_type * raw_ptr;
166 static value_type& node_to_value( node_type& n )
170 static value_type const& node_to_value( node_type const& n )
178 template <typename Q>
179 static node_type * alloc_node( Q const& v )
181 return cxx_allocator().New( v );
184 template <typename... Args>
185 static node_type * alloc_node( Args&&... args )
187 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
190 static void free_node( node_type * pNode )
192 cxx_allocator().Delete( pNode );
195 struct node_disposer {
196 void operator()( node_type * pNode )
201 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
205 return base_class::m_Head;
208 head_type& head() const
210 return const_cast<head_type&>( base_class::m_Head );
215 return base_class::m_Tail;
218 head_type const& tail() const
220 return base_class::m_Tail;
226 template <bool IsConst>
227 class iterator_type: protected base_class::template iterator_type<IsConst>
229 typedef typename base_class::template iterator_type<IsConst> iterator_base;
231 iterator_type( head_type const& pNode )
232 : iterator_base( const_cast<head_type *>( &pNode ))
235 iterator_type( head_type const * pNode )
236 : iterator_base( const_cast<head_type *>( pNode ))
239 friend class LazyList;
242 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
243 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
248 iterator_type( iterator_type const& src )
249 : iterator_base( src )
252 value_ptr operator ->() const
254 typename iterator_base::value_ptr p = iterator_base::operator ->();
255 return p ? &(p->m_Value) : nullptr;
258 value_ref operator *() const
260 return (iterator_base::operator *()).m_Value;
264 iterator_type& operator ++()
266 iterator_base::operator ++();
271 bool operator ==(iterator_type<C> const& i ) const
273 return iterator_base::operator ==(i);
276 bool operator !=(iterator_type<C> const& i ) const
278 return iterator_base::operator !=(i);
285 typedef iterator_type<false> iterator;
287 /// Const forward iterator
289 For iterator's features and requirements see \ref iterator
291 typedef iterator_type<true> const_iterator;
293 /// Returns a forward iterator addressing the first element in a list
295 For empty list \code begin() == end() \endcode
299 iterator it( head() );
300 ++it ; // skip dummy head node
304 /// Returns an iterator that addresses the location succeeding the last element in a list
306 Do not use the value returned by <tt>end</tt> function to access any item.
308 The returned value can be used only to control reaching the end of the list.
309 For empty list \code begin() == end() \endcode
313 return iterator( tail() );
316 /// Returns a forward const iterator addressing the first element in a list
318 const_iterator begin() const
320 const_iterator it( head() );
321 ++it ; // skip dummy head node
324 const_iterator cbegin() const
326 const_iterator it( head() );
327 ++it ; // skip dummy head node
332 /// Returns an const iterator that addresses the location succeeding the last element in a list
334 const_iterator end() const
336 return const_iterator( tail() );
338 const_iterator cend() const
340 return const_iterator( tail() );
345 /// Default constructor
349 /// Desctructor clears the list
357 The function creates a node with copy of \p val value
358 and then inserts the node created into the list.
360 The type \p Q should contain as minimum the complete key of the node.
361 The object of \p value_type should be constructible from \p val of type \p Q.
362 In trivial case, \p Q is equal to \p value_type.
364 The function makes RCU lock internally.
366 Returns \p true if inserting successful, \p false otherwise.
368 template <typename Q>
369 bool insert( Q const& val )
371 return insert_at( head(), val );
376 This function inserts new node with default-constructed value and then it calls
377 \p func functor with signature
378 \code void func( value_type& itemValue ) ;\endcode
380 The argument \p itemValue of user-defined functor \p func is the reference
381 to the list's item inserted.
382 The user-defined functor is called only if the inserting is success.
384 The type \p Q should contain the complete key of the node.
385 The object of \ref value_type should be constructible from \p key of type \p Q.
387 The function allows to split creating of new item into two part:
388 - create item from \p key with initializing key-fields only;
389 - insert new item into the list;
390 - if inserting is successful, initialize non-key fields of item by calling \p f functor
392 This can be useful if complete initialization of object of \p value_type is heavyweight and
393 it is preferable that the initialization should be completed only if inserting is successful.
395 The function makes RCU lock internally.
397 template <typename Q, typename Func>
398 bool insert( Q const& key, Func func )
400 return insert_at( head(), key, func );
403 /// Inserts data of type \p value_type constructed from \p args
405 Returns \p true if inserting successful, \p false otherwise.
407 The function makes RCU lock internally.
409 template <typename... Args>
410 bool emplace( Args&&... args )
412 return emplace_at( head(), std::forward<Args>(args)... );
415 /// Updates data by \p key
417 The operation performs inserting or replacing the element with lock-free manner.
419 If the \p key not found in the list, then the new item created from \p key
420 will be inserted iff \p bAllowInsert is \p true.
421 Otherwise, if \p key is found, the functor \p func is called with item found.
423 The functor \p Func signature is:
426 void operator()( bool bNew, value_type& item, Q const& val );
431 - \p bNew - \p true if the item has been inserted, \p false otherwise
432 - \p item - item of the list
433 - \p val - argument \p key passed into the \p %update() function
435 The functor may change non-key fields of the \p item;
436 during \p func call \p item is locked so it is safe to modify the item in
437 multi-threaded environment.
439 The function applies RCU lock internally.
441 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
442 \p second is true if new item has been added or \p false if the item with \p key
445 template <typename Q, typename Func>
446 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
448 return update_at( head(), key, func, bAllowInsert );
451 template <typename Q, typename Func>
452 CDS_DEPRECATED("ensure() is deprecated, use update()")
453 std::pair<bool, bool> ensure( Q const& key, Func f )
455 return update( key, f, true );
459 /// Deletes \p key from the list
460 /** \anchor cds_nonintrusive_LazyList_rcu_erase
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>
471 bool erase( Q const& key )
473 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
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 "erase(Q const&)"
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>
484 bool erase_with( Q const& key, Less pred )
487 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
490 /// Deletes \p key from the list
491 /** \anchor cds_nonintrusive_LazyList_rcu_erase_func
492 The function searches an item with key \p key, calls \p f functor
493 and deletes the item. If \p key is not found, the functor is not called.
495 The functor \p Func interface:
498 void operator()(value_type const& val) { ... }
502 Since the key of LazyList's item type \p T is not explicitly specified,
503 template parameter \p Q defines the key type searching in the list.
504 The list item comparator should be able to compare the type \p T of list item
507 RCU \p synchronize method can be called. RCU should not be locked.
509 Return \p true if key is found and deleted, \p false otherwise
511 template <typename Q, typename Func>
512 bool erase( Q const& key, Func f )
514 return erase_at( head(), key, intrusive_key_comparator(), f );
517 /// Deletes the item from the list using \p pred predicate for searching
519 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_erase_func "erase(Q const&, Func)"
520 but \p pred is used for key comparing.
521 \p Less functor has the interface like \p std::less.
522 \p pred must imply the same element order as the comparator used for building the list.
524 template <typename Q, typename Less, typename Func>
525 bool erase_with( Q const& key, Less pred, Func f )
528 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
531 /// Extracts an item from the list
533 @anchor cds_nonintrusive_LazyList_rcu_extract
534 The function searches an item with key equal to \p key in the list,
535 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to an item found.
536 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
538 @note The function does NOT call RCU read-side lock or synchronization,
539 and does NOT dispose the item found. It just excludes the item from the list
540 and returns a pointer to item found.
541 You should lock RCU before calling this function.
544 #include <cds/urcu/general_buffered.h>
545 #include <cds/container/lazy_list_rcu.h>
547 typedef cds::urcu::gc< general_buffered<> > rcu;
548 typedef cds::container::LazyList< rcu, Foo > rcu_lazy_list;
550 rcu_lazy_list theList;
553 rcu_lazy_list::exempt_ptr p;
555 // first, we should lock RCU
556 rcu_lazy_list::rcu_lock sl;
558 // Now, you can apply extract function
559 // Note that you must not delete the item found inside the RCU lock
560 p = theList.extract( 10 );
562 // do something with p
566 // Outside RCU lock section we may safely release extracted pointer.
567 // release() passes the pointer to RCU reclamation cycle.
571 template <typename Q>
572 exempt_ptr extract( Q const& key )
574 return exempt_ptr(extract_at( head(), key, intrusive_key_comparator()));
577 /// Extracts an item from the list using \p pred predicate for searching
579 This function is the analog for \p extract(Q const&).
581 The \p pred is a predicate used for key comparing.
582 \p Less has the interface like \p std::less.
583 \p pred must imply the same element order as \ref key_comparator.
585 template <typename Q, typename Less>
586 exempt_ptr extract_with( Q const& key, Less pred )
589 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type()));
592 /// Checks whether the list contains \p key
594 The function searches the item with key equal to \p key
595 and returns \p true if it is found, and \p false otherwise.
597 The function applies RCU lock internally.
599 template <typename Q>
600 bool contains( Q const& key ) const
602 return find_at( head(), key, intrusive_key_comparator() );
605 template <typename Q>
606 CDS_DEPRECATED("deprecated, use contains()")
607 bool find( Q const& key ) const
609 return contains( key );
613 /// Checks whether the list contains \p key using \p pred predicate for searching
615 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
616 \p Less functor has the interface like \p std::less.
617 \p pred must imply the same element order as the comparator used for building the list.
619 template <typename Q, typename Less>
620 bool contains( Q const& key, Less pred ) const
623 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
626 template <typename Q, typename Less>
627 CDS_DEPRECATED("deprecated, use contains()")
628 bool find_with( Q const& key, Less pred ) const
630 return contains( key, pred );
634 /// Finds the key \p key and performs an action with it
635 /** \anchor cds_nonintrusive_LazyList_rcu_find_func
636 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
637 The interface of \p Func functor is:
640 void operator()( value_type& item, Q& key );
643 where \p item is the item found, \p key is the \p find() function argument.
645 The functor may change non-key fields of \p item. Note that the function is only guarantee
646 that \p item cannot be deleted during functor is executing.
647 The function does not serialize simultaneous access to the list \p item. If such access is
648 possible you must provide your own synchronization schema to exclude unsafe item modifications.
650 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
651 may modify both arguments.
653 The function makes RCU lock internally.
655 The function returns \p true if \p key is found, \p false otherwise.
657 template <typename Q, typename Func>
658 bool find( Q& key, Func f ) const
660 return find_at( head(), key, intrusive_key_comparator(), f );
663 template <typename Q, typename Func>
664 bool find( Q const& key, Func f ) const
666 return find_at( head(), key, intrusive_key_comparator(), f );
670 /// Finds the key \p key using \p pred predicate for searching
672 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_find_func "find(Q&, Func)"
673 but \p pred is used for key comparing.
674 \p Less functor has the interface like \p std::less.
675 \p pred must imply the same element order as the comparator used for building the list.
677 template <typename Q, typename Less, typename Func>
678 bool find_with( Q& key, Less pred, Func f ) const
681 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
684 template <typename Q, typename Less, typename Func>
685 bool find_with( Q const& key, Less pred, Func f ) const
688 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
692 /// Finds the key \p key and return the item found
693 /** \anchor cds_nonintrusive_LazyList_rcu_get
694 The function searches the item with key equal to \p key and returns the pointer to item found.
695 If \p key is not found it returns \p nullptr.
697 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
699 RCU should be locked before call of this function.
700 Returned item is valid only while RCU is locked:
702 typedef cds::container::LazyList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
707 ord_list::rcu_lock lock;
709 foo * pVal = theList.get( 5 );
714 // Unlock RCU by rcu_lock destructor
715 // pVal can be freed at any time after RCU has been unlocked
719 template <typename Q>
720 value_type * get( Q const& key ) const
722 return get_at( head(), key, intrusive_key_comparator());
725 /// Finds the key \p key and return the item found
727 The function is an analog of \ref cds_nonintrusive_LazyList_rcu_get "get(Q const&)"
728 but \p pred is used for comparing the keys.
730 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
732 \p pred must imply the same element order as the comparator used for building the list.
734 template <typename Q, typename Less>
735 value_type * get_with( Q const& key, Less pred ) const
738 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
741 /// Checks if the list is empty
744 return base_class::empty();
747 /// Returns list's item count
749 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
750 this function always returns 0.
752 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
753 is empty. To check list emptyness use \ref empty() method.
757 return base_class::size();
768 bool insert_node_at( head_type& refHead, node_type * pNode )
770 assert( pNode != nullptr );
771 scoped_node_ptr p( pNode );
773 if ( base_class::insert_at( &refHead, *pNode )) {
781 template <typename Q>
782 bool insert_at( head_type& refHead, Q const& val )
784 return insert_node_at( refHead, alloc_node( val ));
787 template <typename... Args>
788 bool emplace_at( head_type& refHead, Args&&... args )
790 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
793 template <typename Q, typename Func>
794 bool insert_at( head_type& refHead, Q const& key, Func f )
796 scoped_node_ptr pNode( alloc_node( key ));
798 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
805 template <typename Q, typename Compare, typename Func>
806 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
808 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
811 template <typename Q, typename Compare>
812 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
814 return base_class::extract_at( &refHead, key, cmp );
817 template <typename Q, typename Func>
818 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
820 scoped_node_ptr pNode( alloc_node( key ));
822 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
823 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key );},
825 if ( ret.first && ret.second )
831 template <typename Q, typename Compare>
832 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
834 return base_class::find_at( &refHead, key, cmp, [](node_type&, Q const &) {} );
837 template <typename Q, typename Compare, typename Func>
838 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
840 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
843 template <typename Q, typename Compare>
844 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
846 node_type * pNode = base_class::get_at( &refHead, val, cmp );
847 return pNode ? &pNode->m_Value : nullptr;
853 }} // namespace cds::container
855 #endif // #ifndef CDSLIB_CONTAINER_LAZY_LIST_RCU_H