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::stat stat; ///< Internal statistics
152 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
154 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
155 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
159 typedef typename base_class::value_type node_type;
160 typedef typename maker::cxx_allocator cxx_allocator;
161 typedef typename maker::node_deallocator node_deallocator;
162 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
164 typedef typename base_class::atomic_node_ptr head_type;
168 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
172 struct raw_ptr_converter
174 value_type * operator()( node_type * p ) const
176 return p ? &p->m_Value : nullptr;
179 value_type& operator()( node_type& n ) const
184 value_type const& operator()( node_type const& n ) const
192 /// Result of \p get(), \p get_with() functions - pointer to the node found
193 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
197 static value_type& node_to_value( node_type& n )
201 static value_type const& node_to_value( node_type const& n )
206 template <typename Q>
207 static node_type * alloc_node( Q const& v )
209 return cxx_allocator().New( v );
212 template <typename... Args>
213 static node_type * alloc_node( Args&&... args )
215 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
218 static void free_node( node_type * pNode )
220 cxx_allocator().Delete( pNode );
223 struct node_disposer {
224 void operator()( node_type * pNode )
229 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
233 return base_class::m_pHead;
236 head_type& head() const
238 return const_cast<head_type&>( base_class::m_pHead );
244 template <bool IsConst>
245 class iterator_type: protected base_class::template iterator_type<IsConst>
247 typedef typename base_class::template iterator_type<IsConst> iterator_base;
249 iterator_type( head_type const& pNode )
250 : iterator_base( pNode )
253 friend class MichaelList;
256 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
257 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
262 iterator_type( iterator_type const& src )
263 : iterator_base( src )
266 value_ptr operator ->() const
268 typename iterator_base::value_ptr p = iterator_base::operator ->();
269 return p ? &(p->m_Value) : nullptr;
272 value_ref operator *() const
274 return (iterator_base::operator *()).m_Value;
278 iterator_type& operator ++()
280 iterator_base::operator ++();
285 bool operator ==(iterator_type<C> const& i ) const
287 return iterator_base::operator ==(i);
290 bool operator !=(iterator_type<C> const& i ) const
292 return iterator_base::operator !=(i);
298 ///@name Forward iterators (only for debugging purpose)
302 You may safely use iterators in multi-threaded environment only under RCU lock.
303 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
305 typedef iterator_type<false> iterator;
307 /// Const forward iterator
308 typedef iterator_type<true> const_iterator;
310 /// Returns a forward iterator addressing the first element in a list
312 For empty list \code begin() == end() \endcode
316 return iterator( head() );
319 /// Returns an iterator that addresses the location succeeding the last element in a list
321 Do not use the value returned by <tt>end</tt> function to access any item.
322 Internally, <tt>end</tt> returning value equals to \p nullptr.
324 The returned value can be used only to control reaching the end of the list.
325 For empty list \code begin() == end() \endcode
332 /// Returns a forward const iterator addressing the first element in a list
333 const_iterator begin() const
335 return const_iterator( head() );
338 /// Returns a forward const iterator addressing the first element in a list
339 const_iterator cbegin() const
341 return const_iterator( head() );
344 /// Returns an const iterator that addresses the location succeeding the last element in a list
345 const_iterator end() const
347 return const_iterator();
350 /// Returns an const iterator that addresses the location succeeding the last element in a list
351 const_iterator cend() const
353 return const_iterator();
358 /// Default constructor
360 Initialize empty list
366 template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
367 explicit MichaelList( Stat& st )
383 The function creates a node with copy of \p val value
384 and then inserts the node created into the list.
386 The type \p Q should contain as minimum the complete key of the node.
387 The object of \ref value_type should be constructible from \p val of type \p Q.
388 In trivial case, \p Q is equal to \ref value_type.
390 The function makes RCU lock internally.
392 Returns \p true if inserting successful, \p false otherwise.
394 template <typename Q>
395 bool insert( Q const& val )
397 return insert_at( head(), val );
402 This function inserts new node with default-constructed value and then it calls
403 \p func functor with signature
404 \code void func( value_type& itemValue ) ;\endcode
406 The argument \p itemValue of user-defined functor \p func is the reference
407 to the list's item inserted. User-defined functor \p func should guarantee that during changing
408 item's value no any other changes could be made on this list's item by concurrent threads.
410 The type \p Q should contain the complete key of the node.
411 The object of \ref value_type should be constructible from \p key of type \p Q.
413 The function allows to split creating of new item into two part:
414 - create item from \p key with initializing key-fields only;
415 - insert new item into the list;
416 - if inserting is successful, initialize non-key fields of item by calling \p f functor
418 This can be useful if complete initialization of object of \p value_type is heavyweight and
419 it is preferable that the initialization should be completed only if inserting is successful.
421 The function makes RCU lock internally.
423 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
425 template <typename Q, typename Func>
426 bool insert( Q const& key, Func func )
428 return insert_at( head(), key, func );
431 /// Updates data by \p key
433 The operation performs inserting or replacing the element with lock-free manner.
435 If the \p key not found in the list, then the new item created from \p key
436 will be inserted iff \p bAllowInsert is \p true.
437 Otherwise, if \p key is found, the functor \p func is called with item found.
439 The functor \p Func signature is:
442 void operator()( bool bNew, value_type& item, Q const& val );
447 - \p bNew - \p true if the item has been inserted, \p false otherwise
448 - \p item - item of the list
449 - \p val - argument \p key passed into the \p %update() function
451 The functor may change non-key fields of the \p item; however, \p func must guarantee
452 that during changing no any other modifications could be made on this item by concurrent threads.
454 The function applies RCU lock internally.
456 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
457 \p second is true if new item has been added or \p false if the item with \p key
460 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
462 template <typename Q, typename Func>
463 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
465 return update_at( head(), key, func, bAllowInsert );
468 template <typename Q, typename Func>
469 CDS_DEPRECATED("ensure() is deprecated, use update()")
470 std::pair<bool, bool> ensure( Q const& key, Func f )
472 return update( key, f, true );
476 /// Inserts data of type \ref value_type constructed from \p args
478 Returns \p true if inserting successful, \p false otherwise.
480 The function makes RCU lock internally.
482 template <typename... Args>
483 bool emplace( Args&&... args )
485 return emplace_at( head(), std::forward<Args>(args)... );
488 /// Deletes \p key from the list
489 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
490 Since the key of MichaelList's item type \p value_type is not explicitly specified,
491 template parameter \p Q defines the key type searching in the list.
492 The list item comparator should be able to compare values of the type \p value_type
493 and \p Q in any order.
495 RCU \p synchronize method can be called. RCU should not be locked.
497 Return \p true if key is found and deleted, \p false otherwise
499 template <typename Q>
500 bool erase( Q const& key )
502 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
505 /// Deletes the item from the list using \p pred predicate for searching
507 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
508 but \p pred is used for key comparing.
509 \p Less functor has the interface like \p std::less.
510 \p pred must imply the same element order as the comparator used for building the list.
512 template <typename Q, typename Less>
513 bool erase_with( Q const& key, Less pred )
516 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
519 /// Deletes \p key from the list
520 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
521 The function searches an item with key \p key, calls \p f functor with item found
522 and deletes it. If \p key is not found, the functor is not called.
524 The functor \p Func interface:
527 void operator()(const value_type& val) { ... }
531 Since the key of MichaelList's item type \p value_type is not explicitly specified,
532 template parameter \p Q defines the key type searching in the list.
533 The list item comparator should be able to compare the values of type \p value_type
534 and \p Q in any order.
536 RCU \p synchronize method can be called. RCU should not be locked.
538 Return \p true if key is found and deleted, \p false otherwise
540 template <typename Q, typename Func>
541 bool erase( Q const& key, Func f )
543 return erase_at( head(), key, intrusive_key_comparator(), f );
546 /// Deletes the item from the list using \p pred predicate for searching
548 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
549 but \p pred is used for key comparing.
550 \p Less functor has the interface like \p std::less.
551 \p pred must imply the same element order as the comparator used for building the list.
553 template <typename Q, typename Less, typename Func>
554 bool erase_with( Q const& key, Less pred, Func f )
557 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
560 /// Extracts an item from the list
562 @anchor cds_nonintrusive_MichaelList_rcu_extract
563 The function searches an item with key equal to \p key in the list,
564 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
565 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
567 @note The function does NOT dispose the item found. It just excludes the item from the list
568 and returns a pointer to the item.
569 You shouldn't lock RCU for current thread before calling this function.
572 #include <cds/urcu/general_buffered.h>
573 #include <cds/container/michael_list_rcu.h>
575 typedef cds::urcu::gc< general_buffered<> > rcu;
576 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
578 rcu_michael_list theList;
581 rcu_michael_list::exempt_ptr p;
583 // The RCU should NOT be locked when extract() is called!
584 assert( !rcu::is_locked() );
587 p = theList.extract( 10 )
589 // do something with p
593 // we may safely release extracted pointer here.
594 // release() passes the pointer to RCU reclamation cycle.
598 template <typename Q>
599 exempt_ptr extract( Q const& key )
601 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
604 /// Extracts an item from the list using \p pred predicate for searching
606 This function is the analog for \p extract(Q const&).
608 The \p pred is a predicate used for key comparing.
609 \p Less has the interface like \p std::less.
610 \p pred must imply the same element order as \ref key_comparator.
612 template <typename Q, typename Less>
613 exempt_ptr extract_with( Q const& key, Less pred )
616 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
619 /// Checks whether the list contains \p key
621 The function searches the item with key equal to \p key
622 and returns \p true if it is found, and \p false otherwise.
624 The function applies RCU lock internally.
626 template <typename Q>
627 bool contains( Q const& key )
629 return find_at( head(), key, intrusive_key_comparator() );
632 template <typename Q>
633 CDS_DEPRECATED("deprecated, use contains()")
634 bool find( Q const& key )
636 return contains( key );
640 /// Checks whether the list contains \p key using \p pred predicate for searching
642 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
643 \p Less functor has the interface like \p std::less.
644 \p pred must imply the same element order as the comparator used for building the list.
646 template <typename Q, typename Less>
647 bool contains( Q const& key, Less pred )
650 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
653 // Deprecatd, use contains()
654 template <typename Q, typename Less>
655 bool find_with( Q const& key, Less pred )
658 return contains( key, pred );
662 /// Finds the key \p key and performs an action with it
663 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
664 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
665 The interface of \p Func functor is:
668 void operator()( value_type& item, Q& key );
671 where \p item is the item found, \p key is the \p %find() function argument.
673 The functor may change non-key fields of \p item. Note that the function is only guarantee
674 that \p item cannot be deleted during functor is executing.
675 The function does not serialize simultaneous access to the list \p item. If such access is
676 possible you must provide your own synchronization schema to exclude unsafe item modifications.
678 The function makes RCU lock internally.
680 The function returns \p true if \p val is found, \p false otherwise.
682 template <typename Q, typename Func>
683 bool find( Q& key, Func f )
685 return find_at( head(), key, intrusive_key_comparator(), f );
688 template <typename Q, typename Func>
689 bool find( Q const& key, Func f )
691 return find_at( head(), key, intrusive_key_comparator(), f );
695 /// Finds the key \p key using \p pred predicate for searching
697 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
698 but \p pred is used for key comparing.
699 \p Less functor has the interface like \p std::less.
700 \p pred must imply the same element order as the comparator used for building the list.
702 template <typename Q, typename Less, typename Func>
703 bool find_with( Q& key, Less pred, Func f )
706 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
709 template <typename Q, typename Less, typename Func>
710 bool find_with( Q const& key, Less pred, Func f )
713 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
717 /// Finds the key \p key and return the item found
718 /** \anchor cds_nonintrusive_MichaelList_rcu_get
719 The function searches the item with key equal to \p key and returns the pointer to item found.
720 If \p key is not found it returns an empty \p raw_ptr.
722 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
724 RCU should be locked before call of this function.
725 Returned item is valid only while RCU is locked:
727 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
730 typename ord_list::raw_ptr rp;
733 ord_list::rcu_lock lock;
735 rp = theList.get( 5 );
740 // Unlock RCU by rcu_lock destructor
741 // A value owned by rp can be freed at any time after RCU has been unlocked
743 // You can manually release rp after RCU-locked section
747 template <typename Q>
748 raw_ptr get( Q const& key )
750 return get_at( head(), key, intrusive_key_comparator());
753 /// Finds \p key and return the item found
755 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
756 but \p pred is used for comparing the keys.
758 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
760 \p pred must imply the same element order as the comparator used for building the list.
762 template <typename Q, typename Less>
763 raw_ptr get_with( Q const& key, Less pred )
766 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
769 /// Checks if the list is empty
772 return base_class::empty();
775 /// Returns list's item count
777 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
778 this function always returns 0.
780 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
781 is empty. To check list emptyness use \p empty() method.
785 return base_class::size();
788 /// Returns const reference to internal statistics
789 stat const& statistics() const
791 return base_class::statistics();
802 bool insert_node( node_type * pNode )
804 return insert_node_at( head(), pNode );
807 bool insert_node_at( head_type& refHead, node_type * pNode )
810 scoped_node_ptr p(pNode);
811 if ( base_class::insert_at( refHead, *pNode )) {
819 template <typename Q>
820 bool insert_at( head_type& refHead, Q const& val )
822 return insert_node_at( refHead, alloc_node( val ));
825 template <typename Q, typename Func>
826 bool insert_at( head_type& refHead, Q const& key, Func f )
828 scoped_node_ptr pNode( alloc_node( key ));
830 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
837 template <typename... Args>
838 bool emplace_at( head_type& refHead, Args&&... args )
840 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
843 template <typename Q, typename Compare, typename Func>
844 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
846 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
849 template <typename Q, typename Func>
850 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
852 scoped_node_ptr pNode( alloc_node( key ));
854 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
855 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
857 if ( ret.first && ret.second )
863 template <typename Q, typename Compare>
864 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
866 return base_class::extract_at( refHead, key, cmp );
869 template <typename Q, typename Compare>
870 bool find_at( head_type& refHead, Q const& key, Compare cmp )
872 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
875 template <typename Q, typename Compare, typename Func>
876 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
878 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
881 template <typename Q, typename Compare>
882 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
884 return raw_ptr( base_class::get_at( refHead, val, cmp ));
890 }} // namespace cds::container
892 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H