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_MICHAEL_LIST_RCU_H
32 #define CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
35 #include <cds/container/details/michael_list_base.h>
36 #include <cds/intrusive/michael_list_rcu.h>
37 #include <cds/container/details/make_michael_list.h>
38 #include <cds/details/binary_functor_wrapper.h>
40 namespace cds { namespace container {
42 /// Michael's ordered list (template specialization for \ref cds_urcu_desc "RCU")
43 /** @ingroup cds_nonintrusive_list
44 \anchor cds_nonintrusive_MichaelList_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 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
52 This class is non-intrusive version of \ref cds_intrusive_MichaelList_rcu "cds::intrusive::MichaelList" RCU specialization.
55 - \p RCU - one of \ref cds_urcu_gc "RCU type"
56 - \p T - type stored in the list. The type must be default- and copy-constructible.
57 - \p Traits - type traits, default is michael_list::traits
59 The implementation does not divide type \p T into key and value part and
60 may be used as a main building block for hash set containers.
61 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
62 or <tt>Traits::less</tt> predicate.
64 \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" is a key-value version of Michael's
65 non-intrusive list that is closer to the C++ std library approach.
67 @note Before including <tt><cds/container/michael_list_rcu.h></tt> you should include appropriate RCU header file,
68 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
70 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
71 argument. For example, the following traits-based declaration of Michael's list
74 #include <cds/urcu/general_buffered.h>
75 #include <cds/container/michael_list_rcu.h>
76 // Declare comparator for the item
78 int operator ()( int i1, int i2 )
85 struct my_traits: public cds::container::michael_list::traits
87 typedef my_compare compare;
90 // Declare traits-based list
91 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, my_traits > traits_based_list;
94 is equivalent for the following option-based list
96 #include <cds/urcu/general_buffered.h>
97 #include <cds/container/michael_list_rcu.h>
99 // my_compare is the same
101 // Declare option-based list
102 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int,
103 typename cds::container::michael_list::make_traits<
104 cds::container::opt::compare< my_compare > // item comparator option
109 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
110 - opt::compare - key comparison functor. No default functor is provided.
111 If the option is not specified, the opt::less is used.
112 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
113 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
114 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
115 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
116 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
117 or opt::v::sequential_consistent (sequentially consisnent memory model).
118 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
123 #ifdef CDS_DOXYGEN_INVOKED
124 typename Traits = michael_list::traits
129 class MichaelList< cds::urcu::gc<RCU>, T, Traits > :
130 #ifdef CDS_DOXYGEN_INVOKED
131 protected intrusive::MichaelList< cds::urcu::gc<RCU>, T, Traits >
133 protected details::make_michael_list< cds::urcu::gc<RCU>, T, Traits >::type
137 typedef details::make_michael_list< cds::urcu::gc<RCU>, T, Traits > maker;
138 typedef typename maker::type base_class;
142 typedef cds::urcu::gc<RCU> gc; ///< RCU
143 typedef T value_type; ///< Type of value stored in the list
144 typedef Traits traits; ///< List traits
146 typedef typename base_class::back_off back_off; ///< Back-off strategy used
147 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
148 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
149 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
150 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
151 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
153 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
154 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
158 typedef typename base_class::value_type node_type;
159 typedef typename maker::cxx_allocator cxx_allocator;
160 typedef typename maker::node_deallocator node_deallocator;
161 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
163 typedef typename base_class::atomic_node_ptr head_type;
167 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
171 struct raw_ptr_converter
173 value_type * operator()( node_type * p ) const
175 return p ? &p->m_Value : nullptr;
178 value_type& operator()( node_type& n ) const
183 value_type const& operator()( node_type const& n ) const
191 /// Result of \p get(), \p get_with() functions - pointer to the node found
192 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
196 static value_type& node_to_value( node_type& n )
200 static value_type const& node_to_value( node_type const& n )
205 template <typename Q>
206 static node_type * alloc_node( Q const& v )
208 return cxx_allocator().New( v );
211 template <typename... Args>
212 static node_type * alloc_node( Args&&... args )
214 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
217 static void free_node( node_type * pNode )
219 cxx_allocator().Delete( pNode );
222 struct node_disposer {
223 void operator()( node_type * pNode )
228 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
232 return base_class::m_pHead;
235 head_type& head() const
237 return const_cast<head_type&>( base_class::m_pHead );
243 template <bool IsConst>
244 class iterator_type: protected base_class::template iterator_type<IsConst>
246 typedef typename base_class::template iterator_type<IsConst> iterator_base;
248 iterator_type( head_type const& pNode )
249 : iterator_base( pNode )
252 friend class MichaelList;
255 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
256 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
261 iterator_type( iterator_type const& src )
262 : iterator_base( src )
265 value_ptr operator ->() const
267 typename iterator_base::value_ptr p = iterator_base::operator ->();
268 return p ? &(p->m_Value) : nullptr;
271 value_ref operator *() const
273 return (iterator_base::operator *()).m_Value;
277 iterator_type& operator ++()
279 iterator_base::operator ++();
284 bool operator ==(iterator_type<C> const& i ) const
286 return iterator_base::operator ==(i);
289 bool operator !=(iterator_type<C> const& i ) const
291 return iterator_base::operator !=(i);
297 ///@name Forward iterators (only for debugging purpose)
301 You may safely use iterators in multi-threaded environment only under RCU lock.
302 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
304 typedef iterator_type<false> iterator;
306 /// Const forward iterator
307 typedef iterator_type<true> const_iterator;
309 /// Returns a forward iterator addressing the first element in a list
311 For empty list \code begin() == end() \endcode
315 return iterator( head() );
318 /// Returns an iterator that addresses the location succeeding the last element in a list
320 Do not use the value returned by <tt>end</tt> function to access any item.
321 Internally, <tt>end</tt> returning value equals to \p nullptr.
323 The returned value can be used only to control reaching the end of the list.
324 For empty list \code begin() == end() \endcode
331 /// Returns a forward const iterator addressing the first element in a list
332 const_iterator begin() const
334 return const_iterator( head() );
337 /// Returns a forward const iterator addressing the first element in a list
338 const_iterator cbegin() const
340 return const_iterator( head() );
343 /// Returns an const iterator that addresses the location succeeding the last element in a list
344 const_iterator end() const
346 return const_iterator();
349 /// Returns an const iterator that addresses the location succeeding the last element in a list
350 const_iterator cend() const
352 return const_iterator();
357 /// Default constructor
359 Initialize empty list
375 The function creates a node with copy of \p val value
376 and then inserts the node created into the list.
378 The type \p Q should contain as minimum the complete key of the node.
379 The object of \ref value_type should be constructible from \p val of type \p Q.
380 In trivial case, \p Q is equal to \ref value_type.
382 The function makes RCU lock internally.
384 Returns \p true if inserting successful, \p false otherwise.
386 template <typename Q>
387 bool insert( Q const& val )
389 return insert_at( head(), val );
394 This function inserts new node with default-constructed value and then it calls
395 \p func functor with signature
396 \code void func( value_type& itemValue ) ;\endcode
398 The argument \p itemValue of user-defined functor \p func is the reference
399 to the list's item inserted. User-defined functor \p func should guarantee that during changing
400 item's value no any other changes could be made on this list's item by concurrent threads.
402 The type \p Q should contain the complete key of the node.
403 The object of \ref value_type should be constructible from \p key of type \p Q.
405 The function allows to split creating of new item into two part:
406 - create item from \p key with initializing key-fields only;
407 - insert new item into the list;
408 - if inserting is successful, initialize non-key fields of item by calling \p f functor
410 This can be useful if complete initialization of object of \p value_type is heavyweight and
411 it is preferable that the initialization should be completed only if inserting is successful.
413 The function makes RCU lock internally.
415 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
417 template <typename Q, typename Func>
418 bool insert( Q const& key, Func func )
420 return insert_at( head(), key, func );
423 /// Updates data by \p key
425 The operation performs inserting or replacing the element with lock-free manner.
427 If the \p key not found in the list, then the new item created from \p key
428 will be inserted iff \p bAllowInsert is \p true.
429 Otherwise, if \p key is found, the functor \p func is called with item found.
431 The functor \p Func signature is:
434 void operator()( bool bNew, value_type& item, Q const& val );
439 - \p bNew - \p true if the item has been inserted, \p false otherwise
440 - \p item - item of the list
441 - \p val - argument \p key passed into the \p %update() function
443 The functor may change non-key fields of the \p item; however, \p func must guarantee
444 that during changing no any other modifications could be made on this item by concurrent threads.
446 The function applies RCU lock internally.
448 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
449 \p second is true if new item has been added or \p false if the item with \p key
452 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
454 template <typename Q, typename Func>
455 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
457 return update_at( head(), key, func, bAllowInsert );
460 template <typename Q, typename Func>
461 CDS_DEPRECATED("ensure() is deprecated, use update()")
462 std::pair<bool, bool> ensure( Q const& key, Func f )
464 return update( key, f, true );
468 /// Inserts data of type \ref value_type constructed from \p args
470 Returns \p true if inserting successful, \p false otherwise.
472 The function makes RCU lock internally.
474 template <typename... Args>
475 bool emplace( Args&&... args )
477 return emplace_at( head(), std::forward<Args>(args)... );
480 /// Deletes \p key from the list
481 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
482 Since the key of MichaelList's item type \p value_type is not explicitly specified,
483 template parameter \p Q defines the key type searching in the list.
484 The list item comparator should be able to compare values of the type \p value_type
485 and \p Q in any order.
487 RCU \p synchronize method can be called. RCU should not be locked.
489 Return \p true if key is found and deleted, \p false otherwise
491 template <typename Q>
492 bool erase( Q const& key )
494 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
497 /// Deletes the item from the list using \p pred predicate for searching
499 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
500 but \p pred is used for key comparing.
501 \p Less functor has the interface like \p std::less.
502 \p pred must imply the same element order as the comparator used for building the list.
504 template <typename Q, typename Less>
505 bool erase_with( Q const& key, Less pred )
508 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
511 /// Deletes \p key from the list
512 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
513 The function searches an item with key \p key, calls \p f functor with item found
514 and deletes it. If \p key is not found, the functor is not called.
516 The functor \p Func interface:
519 void operator()(const value_type& val) { ... }
523 Since the key of MichaelList's item type \p value_type is not explicitly specified,
524 template parameter \p Q defines the key type searching in the list.
525 The list item comparator should be able to compare the values of type \p value_type
526 and \p Q in any order.
528 RCU \p synchronize method can be called. RCU should not be locked.
530 Return \p true if key is found and deleted, \p false otherwise
532 template <typename Q, typename Func>
533 bool erase( Q const& key, Func f )
535 return erase_at( head(), key, intrusive_key_comparator(), f );
538 /// Deletes the item from the list using \p pred predicate for searching
540 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
541 but \p pred is used for key comparing.
542 \p Less functor has the interface like \p std::less.
543 \p pred must imply the same element order as the comparator used for building the list.
545 template <typename Q, typename Less, typename Func>
546 bool erase_with( Q const& key, Less pred, Func f )
549 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
552 /// Extracts an item from the list
554 @anchor cds_nonintrusive_MichaelList_rcu_extract
555 The function searches an item with key equal to \p key in the list,
556 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
557 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
559 @note The function does NOT dispose the item found. It just excludes the item from the list
560 and returns a pointer to the item.
561 You shouldn't lock RCU for current thread before calling this function.
564 #include <cds/urcu/general_buffered.h>
565 #include <cds/container/michael_list_rcu.h>
567 typedef cds::urcu::gc< general_buffered<> > rcu;
568 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
570 rcu_michael_list theList;
573 rcu_michael_list::exempt_ptr p;
575 // The RCU should NOT be locked when extract() is called!
576 assert( !rcu::is_locked() );
579 p = theList.extract( 10 )
581 // do something with p
585 // we may safely release extracted pointer here.
586 // release() passes the pointer to RCU reclamation cycle.
590 template <typename Q>
591 exempt_ptr extract( Q const& key )
593 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
596 /// Extracts an item from the list using \p pred predicate for searching
598 This function is the analog for \p extract(Q const&).
600 The \p pred is a predicate used for key comparing.
601 \p Less has the interface like \p std::less.
602 \p pred must imply the same element order as \ref key_comparator.
604 template <typename Q, typename Less>
605 exempt_ptr extract_with( Q const& key, Less pred )
608 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
611 /// Checks whether the list contains \p key
613 The function searches the item with key equal to \p key
614 and returns \p true if it is found, and \p false otherwise.
616 The function applies RCU lock internally.
618 template <typename Q>
619 bool contains( Q const& key )
621 return find_at( head(), key, intrusive_key_comparator() );
624 template <typename Q>
625 CDS_DEPRECATED("deprecated, use contains()")
626 bool find( Q const& key )
628 return contains( key );
632 /// Checks whether the list contains \p key using \p pred predicate for searching
634 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
635 \p Less functor has the interface like \p std::less.
636 \p pred must imply the same element order as the comparator used for building the list.
638 template <typename Q, typename Less>
639 bool contains( Q const& key, Less pred )
642 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
645 // Deprecatd, use contains()
646 template <typename Q, typename Less>
647 bool find_with( Q const& key, Less pred )
650 return contains( key, pred );
654 /// Finds the key \p key and performs an action with it
655 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
656 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
657 The interface of \p Func functor is:
660 void operator()( value_type& item, Q& key );
663 where \p item is the item found, \p key is the \p %find() function argument.
665 The functor may change non-key fields of \p item. Note that the function is only guarantee
666 that \p item cannot be deleted during functor is executing.
667 The function does not serialize simultaneous access to the list \p item. If such access is
668 possible you must provide your own synchronization schema to exclude unsafe item modifications.
670 The function makes RCU lock internally.
672 The function returns \p true if \p val is found, \p false otherwise.
674 template <typename Q, typename Func>
675 bool find( Q& key, Func f )
677 return find_at( head(), key, intrusive_key_comparator(), f );
680 template <typename Q, typename Func>
681 bool find( Q const& key, Func f )
683 return find_at( head(), key, intrusive_key_comparator(), f );
687 /// Finds the key \p key using \p pred predicate for searching
689 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
690 but \p pred is used for key comparing.
691 \p Less functor has the interface like \p std::less.
692 \p pred must imply the same element order as the comparator used for building the list.
694 template <typename Q, typename Less, typename Func>
695 bool find_with( Q& key, Less pred, Func f )
698 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
701 template <typename Q, typename Less, typename Func>
702 bool find_with( Q const& key, Less pred, Func f )
705 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
709 /// Finds the key \p key and return the item found
710 /** \anchor cds_nonintrusive_MichaelList_rcu_get
711 The function searches the item with key equal to \p key and returns the pointer to item found.
712 If \p key is not found it returns an empty \p raw_ptr.
714 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
716 RCU should be locked before call of this function.
717 Returned item is valid only while RCU is locked:
719 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
722 typename ord_list::raw_ptr rp;
725 ord_list::rcu_lock lock;
727 rp = theList.get( 5 );
732 // Unlock RCU by rcu_lock destructor
733 // A value owned by rp can be freed at any time after RCU has been unlocked
735 // You can manually release rp after RCU-locked section
739 template <typename Q>
740 raw_ptr get( Q const& key )
742 return get_at( head(), key, intrusive_key_comparator());
745 /// Finds \p key and return the item found
747 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
748 but \p pred is used for comparing the keys.
750 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
752 \p pred must imply the same element order as the comparator used for building the list.
754 template <typename Q, typename Less>
755 raw_ptr get_with( Q const& key, Less pred )
758 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
761 /// Checks if the list is empty
764 return base_class::empty();
767 /// Returns list's item count
769 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
770 this function always returns 0.
772 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
773 is empty. To check list emptyness use \p empty() method.
777 return base_class::size();
788 bool insert_node( node_type * pNode )
790 return insert_node_at( head(), pNode );
793 bool insert_node_at( head_type& refHead, node_type * pNode )
796 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 Q, typename Func>
812 bool insert_at( head_type& refHead, Q const& key, Func f )
814 scoped_node_ptr pNode( alloc_node( key ));
816 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
823 template <typename... Args>
824 bool emplace_at( head_type& refHead, Args&&... args )
826 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
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 Func>
836 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
838 scoped_node_ptr pNode( alloc_node( key ));
840 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
841 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
843 if ( ret.first && ret.second )
849 template <typename Q, typename Compare>
850 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
852 return base_class::extract_at( refHead, key, cmp );
855 template <typename Q, typename Compare>
856 bool find_at( head_type& refHead, Q const& key, Compare cmp )
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 )
864 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
867 template <typename Q, typename Compare>
868 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
870 return raw_ptr( base_class::get_at( refHead, val, cmp ));
876 }} // namespace cds::container
878 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H