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 )
208 template <typename Q>
209 static node_type * alloc_node( Q const& v )
211 return cxx_allocator().New( v );
214 template <typename... Args>
215 static node_type * alloc_node( Args&&... args )
217 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
220 static void free_node( node_type * pNode )
222 cxx_allocator().Delete( pNode );
225 struct node_disposer {
226 void operator()( node_type * pNode )
231 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
235 return base_class::m_pHead;
238 head_type& head() const
240 return const_cast<head_type&>( base_class::m_pHead );
246 template <bool IsConst>
247 class iterator_type: protected base_class::template iterator_type<IsConst>
249 typedef typename base_class::template iterator_type<IsConst> iterator_base;
251 iterator_type( head_type const& pNode )
252 : iterator_base( pNode )
255 friend class MichaelList;
258 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
259 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
264 iterator_type( iterator_type const& src )
265 : iterator_base( src )
268 value_ptr operator ->() const
270 typename iterator_base::value_ptr p = iterator_base::operator ->();
271 return p ? &(p->m_Value) : nullptr;
274 value_ref operator *() const
276 return (iterator_base::operator *()).m_Value;
280 iterator_type& operator ++()
282 iterator_base::operator ++();
287 bool operator ==(iterator_type<C> const& i ) const
289 return iterator_base::operator ==(i);
292 bool operator !=(iterator_type<C> const& i ) const
294 return iterator_base::operator !=(i);
300 ///@name Forward iterators (only for debugging purpose)
304 You may safely use iterators in multi-threaded environment only under RCU lock.
305 Otherwise, a crash is possible if another thread deletes the item the iterator points to.
307 typedef iterator_type<false> iterator;
309 /// Const forward iterator
310 typedef iterator_type<true> const_iterator;
312 /// Returns a forward iterator addressing the first element in a list
314 For empty list \code begin() == end() \endcode
318 return iterator( head() );
321 /// Returns an iterator that addresses the location succeeding the last element in a list
323 Do not use the value returned by <tt>end</tt> function to access any item.
324 Internally, <tt>end</tt> returning value equals to \p nullptr.
326 The returned value can be used only to control reaching the end of the list.
327 For empty list \code begin() == end() \endcode
334 /// Returns a forward const iterator addressing the first element in a list
335 const_iterator begin() const
337 return const_iterator( head() );
340 /// Returns a forward const iterator addressing the first element in a list
341 const_iterator cbegin() const
343 return const_iterator( head() );
346 /// Returns an const iterator that addresses the location succeeding the last element in a list
347 const_iterator end() const
349 return const_iterator();
352 /// Returns an const iterator that addresses the location succeeding the last element in a list
353 const_iterator cend() const
355 return const_iterator();
360 /// Default constructor
362 Initialize empty list
378 The function creates a node with copy of \p val value
379 and then inserts the node created into the list.
381 The type \p Q should contain as minimum the complete key of the node.
382 The object of \ref value_type should be constructible from \p val of type \p Q.
383 In trivial case, \p Q is equal to \ref value_type.
385 The function makes RCU lock internally.
387 Returns \p true if inserting successful, \p false otherwise.
389 template <typename Q>
390 bool insert( Q const& val )
392 return insert_at( head(), val );
397 This function inserts new node with default-constructed value and then it calls
398 \p func functor with signature
399 \code void func( value_type& itemValue ) ;\endcode
401 The argument \p itemValue of user-defined functor \p func is the reference
402 to the list's item inserted. User-defined functor \p func should guarantee that during changing
403 item's value no any other changes could be made on this list's item by concurrent threads.
405 The type \p Q should contain the complete key of the node.
406 The object of \ref value_type should be constructible from \p key of type \p Q.
408 The function allows to split creating of new item into two part:
409 - create item from \p key with initializing key-fields only;
410 - insert new item into the list;
411 - if inserting is successful, initialize non-key fields of item by calling \p f functor
413 This can be useful if complete initialization of object of \p value_type is heavyweight and
414 it is preferable that the initialization should be completed only if inserting is successful.
416 The function makes RCU lock internally.
418 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
420 template <typename Q, typename Func>
421 bool insert( Q const& key, Func func )
423 return insert_at( head(), key, func );
426 /// Updates data by \p key
428 The operation performs inserting or replacing the element with lock-free manner.
430 If the \p key not found in the list, then the new item created from \p key
431 will be inserted iff \p bAllowInsert is \p true.
432 Otherwise, if \p key is found, the functor \p func is called with item found.
434 The functor \p Func signature is:
437 void operator()( bool bNew, value_type& item, Q const& val );
442 - \p bNew - \p true if the item has been inserted, \p false otherwise
443 - \p item - item of the list
444 - \p val - argument \p key passed into the \p %update() function
446 The functor may change non-key fields of the \p item; however, \p func must guarantee
447 that during changing no any other modifications could be made on this item by concurrent threads.
449 The function applies RCU lock internally.
451 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
452 \p second is true if new item has been added or \p false if the item with \p key
455 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
457 template <typename Q, typename Func>
458 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
460 return update_at( head(), key, func, bAllowInsert );
463 template <typename Q, typename Func>
464 CDS_DEPRECATED("ensure() is deprecated, use update()")
465 std::pair<bool, bool> ensure( Q const& key, Func f )
467 return update( key, f, true );
471 /// Inserts data of type \ref value_type constructed from \p args
473 Returns \p true if inserting successful, \p false otherwise.
475 The function makes RCU lock internally.
477 template <typename... Args>
478 bool emplace( Args&&... args )
480 return emplace_at( head(), std::forward<Args>(args)... );
483 /// Deletes \p key from the list
484 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
485 Since the key of MichaelList's item type \p value_type is not explicitly specified,
486 template parameter \p Q defines the key type searching in the list.
487 The list item comparator should be able to compare values of the type \p value_type
488 and \p Q in any order.
490 RCU \p synchronize method can be called. RCU should not be locked.
492 Return \p true if key is found and deleted, \p false otherwise
494 template <typename Q>
495 bool erase( Q const& key )
497 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
500 /// Deletes the item from the list using \p pred predicate for searching
502 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
503 but \p pred is used for key comparing.
504 \p Less functor has the interface like \p std::less.
505 \p pred must imply the same element order as the comparator used for building the list.
507 template <typename Q, typename Less>
508 bool erase_with( Q const& key, Less pred )
511 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
514 /// Deletes \p key from the list
515 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
516 The function searches an item with key \p key, calls \p f functor with item found
517 and deletes it. If \p key is not found, the functor is not called.
519 The functor \p Func interface:
522 void operator()(const value_type& val) { ... }
526 Since the key of MichaelList's item type \p value_type is not explicitly specified,
527 template parameter \p Q defines the key type searching in the list.
528 The list item comparator should be able to compare the values of type \p value_type
529 and \p Q in any order.
531 RCU \p synchronize method can be called. RCU should not be locked.
533 Return \p true if key is found and deleted, \p false otherwise
535 template <typename Q, typename Func>
536 bool erase( Q const& key, Func f )
538 return erase_at( head(), key, intrusive_key_comparator(), f );
541 /// Deletes the item from the list using \p pred predicate for searching
543 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
544 but \p pred is used for key comparing.
545 \p Less functor has the interface like \p std::less.
546 \p pred must imply the same element order as the comparator used for building the list.
548 template <typename Q, typename Less, typename Func>
549 bool erase_with( Q const& key, Less pred, Func f )
552 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
555 /// Extracts an item from the list
557 @anchor cds_nonintrusive_MichaelList_rcu_extract
558 The function searches an item with key equal to \p key in the list,
559 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
560 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
562 @note The function does NOT dispose the item found. It just excludes the item from the list
563 and returns a pointer to the item.
564 You shouldn't lock RCU for current thread before calling this function.
567 #include <cds/urcu/general_buffered.h>
568 #include <cds/container/michael_list_rcu.h>
570 typedef cds::urcu::gc< general_buffered<> > rcu;
571 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
573 rcu_michael_list theList;
576 rcu_michael_list::exempt_ptr p;
578 // The RCU should NOT be locked when extract() is called!
579 assert( !rcu::is_locked() );
582 p = theList.extract( 10 )
584 // do something with p
588 // we may safely release extracted pointer here.
589 // release() passes the pointer to RCU reclamation cycle.
593 template <typename Q>
594 exempt_ptr extract( Q const& key )
596 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
599 /// Extracts an item from the list using \p pred predicate for searching
601 This function is the analog for \p extract(Q const&).
603 The \p pred is a predicate used for key comparing.
604 \p Less has the interface like \p std::less.
605 \p pred must imply the same element order as \ref key_comparator.
607 template <typename Q, typename Less>
608 exempt_ptr extract_with( Q const& key, Less pred )
611 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
614 /// Checks whether the list contains \p key
616 The function searches the item with key equal to \p key
617 and returns \p true if it is found, and \p false otherwise.
619 The function applies RCU lock internally.
621 template <typename Q>
622 bool contains( Q const& key )
624 return find_at( head(), key, intrusive_key_comparator() );
627 template <typename Q>
628 CDS_DEPRECATED("deprecated, use contains()")
629 bool find( Q const& key )
631 return contains( key );
635 /// Checks whether the list contains \p key using \p pred predicate for searching
637 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
638 \p Less functor has the interface like \p std::less.
639 \p pred must imply the same element order as the comparator used for building the list.
641 template <typename Q, typename Less>
642 bool contains( Q const& key, Less pred )
645 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
648 // Deprecatd, use contains()
649 template <typename Q, typename Less>
650 bool find_with( Q const& key, Less pred )
653 return contains( key, pred );
657 /// Finds the key \p key and performs an action with it
658 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
659 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
660 The interface of \p Func functor is:
663 void operator()( value_type& item, Q& key );
666 where \p item is the item found, \p key is the \p %find() function argument.
668 The functor may change non-key fields of \p item. Note that the function is only guarantee
669 that \p item cannot be deleted during functor is executing.
670 The function does not serialize simultaneous access to the list \p item. If such access is
671 possible you must provide your own synchronization schema to exclude unsafe item modifications.
673 The function makes RCU lock internally.
675 The function returns \p true if \p val is found, \p false otherwise.
677 template <typename Q, typename Func>
678 bool find( Q& key, Func f )
680 return find_at( head(), key, intrusive_key_comparator(), f );
683 template <typename Q, typename Func>
684 bool find( Q const& key, Func f )
686 return find_at( head(), key, intrusive_key_comparator(), f );
690 /// Finds the key \p key using \p pred predicate for searching
692 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
693 but \p pred is used for key comparing.
694 \p Less functor has the interface like \p std::less.
695 \p pred must imply the same element order as the comparator used for building the list.
697 template <typename Q, typename Less, typename Func>
698 bool find_with( Q& key, Less pred, Func f )
701 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
704 template <typename Q, typename Less, typename Func>
705 bool find_with( Q const& key, Less pred, Func f )
708 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
712 /// Finds the key \p key and return the item found
713 /** \anchor cds_nonintrusive_MichaelList_rcu_get
714 The function searches the item with key equal to \p key and returns the pointer to item found.
715 If \p key is not found it returns an empty \p raw_ptr.
717 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
719 RCU should be locked before call of this function.
720 Returned item is valid only while RCU is locked:
722 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
725 typename ord_list::raw_ptr rp;
728 ord_list::rcu_lock lock;
730 rp = theList.get( 5 );
735 // Unlock RCU by rcu_lock destructor
736 // A value owned by rp can be freed at any time after RCU has been unlocked
738 // You can manually release rp after RCU-locked section
742 template <typename Q>
743 raw_ptr get( Q const& key )
745 return get_at( head(), key, intrusive_key_comparator());
748 /// Finds \p key and return the item found
750 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
751 but \p pred is used for comparing the keys.
753 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
755 \p pred must imply the same element order as the comparator used for building the list.
757 template <typename Q, typename Less>
758 raw_ptr get_with( Q const& key, Less pred )
761 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
764 /// Checks if the list is empty
767 return base_class::empty();
770 /// Returns list's item count
772 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
773 this function always returns 0.
775 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
776 is empty. To check list emptyness use \p empty() method.
780 return base_class::size();
791 bool insert_node_at( head_type& refHead, node_type * pNode )
794 scoped_node_ptr p(pNode);
795 if ( base_class::insert_at( refHead, *pNode )) {
803 template <typename Q>
804 bool insert_at( head_type& refHead, Q const& val )
806 return insert_node_at( refHead, alloc_node( val ));
809 template <typename Q, typename Func>
810 bool insert_at( head_type& refHead, Q const& key, Func f )
812 scoped_node_ptr pNode( alloc_node( key ));
814 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
821 template <typename... Args>
822 bool emplace_at( head_type& refHead, Args&&... args )
824 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
827 template <typename Q, typename Compare, typename Func>
828 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
830 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
833 template <typename Q, typename Func>
834 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
836 scoped_node_ptr pNode( alloc_node( key ));
838 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
839 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
841 if ( ret.first && ret.second )
847 template <typename Q, typename Compare>
848 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
850 return base_class::extract_at( refHead, key, cmp );
853 template <typename Q, typename Compare>
854 bool find_at( head_type& refHead, Q const& key, Compare cmp )
856 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
859 template <typename Q, typename Compare, typename Func>
860 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
862 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
865 template <typename Q, typename Compare>
866 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
868 return raw_ptr( base_class::get_at( refHead, val, cmp ));
874 }} // namespace cds::container
876 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H