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_IMPL_MICHAEL_LIST_H
32 #define CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
39 /// Michael's ordered list
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_MichaelList_gc
43 Usually, ordered single-linked list is used as a building block for the hash table implementation.
44 The complexity of searching is <tt>O(N)</tt>, where \p N is the item count in the list, not in the
48 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
50 This class is non-intrusive version of cds::intrusive::MichaelList class
53 - \p GC - garbage collector used
54 - \p T - type stored in the list. The type must be default- and copy-constructible.
55 - \p Traits - type traits, default is \p michael_list::traits
57 Unlike standard container, this implementation does not divide type \p T into key and value part and
58 may be used as a main building block for hash set algorithms.
59 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
60 or <tt>Traits::less</tt> predicate
62 MichaelKVList is a key-value version of Michael's non-intrusive list that is closer to the C++ std library approach.
64 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
65 argument. For example, the following traits-based declaration of gc::HP Michael's list
67 #include <cds/container/michael_list_hp.h>
68 // Declare comparator for the item
70 int operator ()( int i1, int i2 )
77 struct my_traits: public cds::container::michael_list::traits
79 typedef my_compare compare;
82 // Declare traits-based list
83 typedef cds::container::MichaelList< cds::gc::HP, int, my_traits > traits_based_list;
86 is equivalent for the following option-based list
88 #include <cds/container/michael_list_hp.h>
90 // my_compare is the same
92 // Declare option-based list
93 typedef cds::container::MichaelList< cds::gc::HP, int,
94 typename cds::container::michael_list::make_traits<
95 cds::container::opt::compare< my_compare > // item comparator option
101 There are different specializations of this template for each garbage collecting schema used.
102 You should include appropriate .h-file depending on GC you are using:
103 - for gc::HP: \code #include <cds/container/michael_list_hp.h> \endcode
104 - for gc::DHP: \code #include <cds/container/michael_list_dhp.h> \endcode
105 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/michael_list_rcu.h> \endcode
106 - for gc::nogc: \code #include <cds/container/michael_list_nogc.h> \endcode
111 #ifdef CDS_DOXYGEN_INVOKED
112 typename Traits = michael_list::traits
118 #ifdef CDS_DOXYGEN_INVOKED
119 protected intrusive::MichaelList< GC, T, Traits >
121 protected details::make_michael_list< GC, T, Traits >::type
125 typedef details::make_michael_list< GC, T, Traits > maker;
126 typedef typename maker::type base_class;
130 typedef T value_type; ///< Type of value stored in the list
131 typedef Traits traits; ///< List traits
133 typedef typename base_class::gc gc; ///< Garbage collector used
134 typedef typename base_class::back_off back_off; ///< Back-off strategy used
135 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
136 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
137 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
138 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See \p cds::opt::memory_model option
142 typedef typename base_class::value_type node_type;
143 typedef typename maker::cxx_allocator cxx_allocator;
144 typedef typename maker::node_deallocator node_deallocator;
145 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
147 typedef typename base_class::atomic_node_ptr head_type;
152 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
156 static value_type& node_to_value( node_type& n )
160 static value_type const& node_to_value( node_type const& n )
168 template <typename Q>
169 static node_type * alloc_node( Q const& v )
171 return cxx_allocator().New( v );
174 template <typename... Args>
175 static node_type * alloc_node( Args&&... args )
177 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
180 static void free_node( node_type * pNode )
182 cxx_allocator().Delete( pNode );
185 struct node_disposer {
186 void operator()( node_type * pNode )
191 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
195 return base_class::m_pHead;
198 head_type const& head() const
200 return base_class::m_pHead;
206 template <bool IsConst>
207 class iterator_type: protected base_class::template iterator_type<IsConst>
209 typedef typename base_class::template iterator_type<IsConst> iterator_base;
211 iterator_type( head_type const& pNode )
212 : iterator_base( pNode )
215 friend class MichaelList;
218 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
219 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
224 iterator_type( iterator_type const& src )
225 : iterator_base( src )
228 value_ptr operator ->() const
230 typename iterator_base::value_ptr p = iterator_base::operator ->();
231 return p ? &(p->m_Value) : nullptr;
234 value_ref operator *() const
236 return (iterator_base::operator *()).m_Value;
240 iterator_type& operator ++()
242 iterator_base::operator ++();
247 bool operator ==(iterator_type<C> const& i ) const
249 return iterator_base::operator ==(i);
252 bool operator !=(iterator_type<C> const& i ) const
254 return iterator_base::operator !=(i);
262 The forward iterator for Michael's list has some features:
263 - it has no post-increment operator
264 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
265 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
266 may be thrown if a limit of guard count per thread is exceeded.
267 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
268 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
269 deleting operations it is no guarantee that you iterate all item in the list.
271 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
272 for debug purpose only.
274 typedef iterator_type<false> iterator;
276 /// Const forward iterator
278 For iterator's features and requirements see \ref iterator
280 typedef iterator_type<true> const_iterator;
282 /// Returns a forward iterator addressing the first element in a list
284 For empty list \code begin() == end() \endcode
288 return iterator( head() );
291 /// Returns an iterator that addresses the location succeeding the last element in a list
293 Do not use the value returned by <tt>end</tt> function to access any item.
294 Internally, <tt>end</tt> returning value equals to \p nullptr.
296 The returned value can be used only to control reaching the end of the list.
297 For empty list \code begin() == end() \endcode
304 /// Returns a forward const iterator addressing the first element in a list
306 const_iterator begin() const
308 return const_iterator( head() );
310 const_iterator cbegin() const
312 return const_iterator( head() );
316 /// Returns an const iterator that addresses the location succeeding the last element in a list
318 const_iterator end() const
320 return const_iterator();
322 const_iterator cend() const
324 return const_iterator();
329 /// Default constructor
331 Initialize empty list
347 The function creates a node with copy of \p val value
348 and then inserts the node created into the list.
350 The type \p Q should contain least the complete key of the node.
351 The object of \ref value_type should be constructible from \p val of type \p Q.
352 In trivial case, \p Q is equal to \ref value_type.
354 Returns \p true if inserting successful, \p false otherwise.
356 template <typename Q>
357 bool insert( Q const& val )
359 return insert_at( head(), val );
364 This function inserts new node with default-constructed value and then it calls
365 \p func functor with signature
366 \code void func( value_type& itemValue ) ;\endcode
368 The argument \p itemValue of user-defined functor \p func is the reference
369 to the list's item inserted. User-defined functor \p func should guarantee that during changing
370 item's value no any other changes could be made on this list's item by concurrent threads.
371 The user-defined functor is called only if inserting is success.
373 The type \p Q should contain the complete key of the node.
374 The object of \p value_type should be constructible from \p key of type \p Q.
376 The function allows to split creating of new item into two part:
377 - create item from \p key with initializing key-fields only;
378 - insert new item into the list;
379 - if inserting is successful, initialize non-key fields of item by calling \p func functor
381 The method can be useful if complete initialization of object of \p value_type is heavyweight and
382 it is preferable that the initialization should be completed only if inserting is successful.
384 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
386 template <typename Q, typename Func>
387 bool insert( Q const& key, Func func )
389 return insert_at( head(), key, func );
392 /// Updates data by \p key
394 The operation performs inserting or replacing the element with lock-free manner.
396 If the \p key not found in the list, then the new item created from \p key
397 will be inserted iff \p bAllowInsert is \p true.
398 Otherwise, if \p key is found, the functor \p func is called with item found.
400 The functor \p Func signature is:
403 void operator()( bool bNew, value_type& item, Q const& val );
408 - \p bNew - \p true if the item has been inserted, \p false otherwise
409 - \p item - item of the list
410 - \p val - argument \p key passed into the \p %update() function
412 The functor may change non-key fields of the \p item; however, \p func must guarantee
413 that during changing no any other modifications could be made on this item by concurrent threads.
415 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
416 \p second is true if new item has been added or \p false if the item with \p key
419 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
421 template <typename Q, typename Func>
422 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
424 return update_at( head(), key, func, bAllowInsert );
427 template <typename Q, typename Func>
428 CDS_DEPRECATED("ensure() is deprecated, use update()")
429 std::pair<bool, bool> ensure( Q const& key, Func func )
431 return update( key, func );
435 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
437 Returns \p true if inserting successful, \p false otherwise.
439 template <typename... Args>
440 bool emplace( Args&&... args )
442 return emplace_at( head(), std::forward<Args>(args)... );
445 /// Delete \p key from the list
446 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
447 Since the key of MichaelList's item type \p value_type is not explicitly specified,
448 template parameter \p Q sould contain the complete key to search in the list.
449 The list item comparator should be able to compare the type \p value_type
452 Return \p true if key is found and deleted, \p false otherwise
454 template <typename Q>
455 bool erase( Q const& key )
457 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
460 /// Deletes the item from the list using \p pred predicate for searching
462 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
463 but \p pred is used for key comparing.
464 \p Less functor has the interface like \p std::less.
465 \p pred must imply the same element order as the comparator used for building the list.
467 template <typename Q, typename Less>
468 bool erase_with( Q const& key, Less pred )
471 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
474 /// Deletes \p key from the list
475 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
476 The function searches an item with key \p key, calls \p f functor with item found
477 and deletes it. If \p key is not found, the functor is not called.
479 The functor \p Func interface:
482 void operator()(const value_type& val) { ... }
486 Since the key of MichaelList's item type \p value_type is not explicitly specified,
487 template parameter \p Q should contain the complete key to search in the list.
488 The list item comparator should be able to compare the type \p value_type of list item
491 Return \p true if key is found and deleted, \p false otherwise
493 template <typename Q, typename Func>
494 bool erase( Q const& key, Func f )
496 return erase_at( head(), key, intrusive_key_comparator(), f );
499 /// Deletes the item from the list using \p pred predicate for searching
501 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
502 but \p pred is used for key comparing.
503 \p Less functor has the interface like \p std::less.
504 \p pred must imply the same element order as the comparator used for building the list.
506 template <typename Q, typename Less, typename Func>
507 bool erase_with( Q const& key, Less pred, Func f )
510 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
513 /// Extracts the item from the list with specified \p key
514 /** \anchor cds_nonintrusive_MichaelList_hp_extract
515 The function searches an item with key equal to \p key,
516 unlinks it from the list, and returns it as \p guarded_ptr.
517 If \p key is not found the function returns an empty guarded pointer.
519 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
521 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
525 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
529 ord_list::guarded_ptr gp(theList.extract( 5 ));
534 // Destructor of gp releases internal HP guard and frees the item
538 template <typename Q>
539 guarded_ptr extract( Q const& key )
542 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
546 /// Extracts the item from the list with comparing functor \p pred
548 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(Q const&)"
549 but \p pred predicate is used for key comparing.
551 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
553 \p pred must imply the same element order as the comparator used for building the list.
555 template <typename Q, typename Less>
556 guarded_ptr extract_with( Q const& key, Less pred )
560 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
564 /// Checks whether the list contains \p key
566 The function searches the item with key equal to \p key
567 and returns \p true if it is found, and \p false otherwise.
569 template <typename Q>
570 bool contains( Q const& key )
572 return find_at( head(), key, intrusive_key_comparator() );
575 template <typename Q>
576 CDS_DEPRECATED("deprecated, use contains()")
577 bool find( Q const& key )
579 return contains( key );
583 /// Checks whether the list contains \p key using \p pred predicate for searching
585 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
586 \p Less functor has the interface like \p std::less.
587 \p pred must imply the same element order as the comparator used for building the list.
589 template <typename Q, typename Less>
590 bool contains( Q const& key, Less pred )
593 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
596 template <typename Q, typename Less>
597 CDS_DEPRECATED("deprecated, use contains()")
598 bool find_with( Q const& key, Less pred )
600 return contains( key, pred );
604 /// Finds \p key and perform an action with it
605 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
606 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
607 The interface of \p Func functor is:
610 void operator()( value_type& item, Q& key );
613 where \p item is the item found, \p key is the <tt>find</tt> function argument.
615 The functor may change non-key fields of \p item. Note that the function is only guarantee
616 that \p item cannot be deleted during functor is executing.
617 The function does not serialize simultaneous access to the list \p item. If such access is
618 possible you must provide your own synchronization schema to exclude unsafe item modifications.
620 The function returns \p true if \p key is found, \p false otherwise.
622 template <typename Q, typename Func>
623 bool find( Q& key, Func f )
625 return find_at( head(), key, intrusive_key_comparator(), f );
628 template <typename Q, typename Func>
629 bool find( Q const& key, Func f )
631 return find_at( head(), key, intrusive_key_comparator(), f );
635 /// Finds \p key using \p pred predicate for searching
637 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
638 but \p pred is used for key comparing.
639 \p Less functor has the interface like \p std::less.
640 \p pred must imply the same element order as the comparator used for building the list.
642 template <typename Q, typename Less, typename Func>
643 bool find_with( Q& key, Less pred, Func f )
646 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
649 template <typename Q, typename Less, typename Func>
650 bool find_with( Q const& key, Less pred, Func f )
653 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
657 /// Finds \p key and return the item found
658 /** \anchor cds_nonintrusive_MichaelList_hp_get
659 The function searches the item with key equal to \p key
660 and returns it as \p guarded_ptr.
661 If \p key is not found the function returns an empty guarded pointer.
663 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
667 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
671 ord_list::guarded_ptr gp(theList.get( 5 ));
676 // Destructor of guarded_ptr releases internal HP guard and frees the item
680 Note the compare functor specified for class \p Traits template parameter
681 should accept a parameter of type \p Q that can be not the same as \p value_type.
683 template <typename Q>
684 guarded_ptr get( Q const& key )
687 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
691 /// Finds \p key and return the item found
693 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
694 but \p pred is used for comparing the keys.
696 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
698 \p pred must imply the same element order as the comparator used for building the list.
700 template <typename Q, typename Less>
701 guarded_ptr get_with( Q const& key, Less pred )
705 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
709 /// Check if the list is empty
712 return base_class::empty();
715 /// Returns list's item count
717 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
718 this function always returns 0.
720 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
721 is empty. To check list emptyness use \p empty() method.
725 return base_class::size();
736 bool insert_node_at( head_type& refHead, node_type * pNode )
739 scoped_node_ptr p(pNode);
740 if ( base_class::insert_at( refHead, *pNode )) {
748 template <typename Q>
749 bool insert_at( head_type& refHead, Q const& val )
751 return insert_node_at( refHead, alloc_node( val ));
754 template <typename Q, typename Func>
755 bool insert_at( head_type& refHead, Q const& key, Func f )
757 scoped_node_ptr pNode( alloc_node( key ));
759 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
766 template <typename... Args>
767 bool emplace_at( head_type& refHead, Args&&... args )
769 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
772 template <typename Q, typename Compare, typename Func>
773 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
775 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
778 template <typename Q, typename Compare>
779 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
781 return base_class::extract_at( refHead, guard, key, cmp );
784 template <typename Q, typename Func>
785 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
787 scoped_node_ptr pNode( alloc_node( key ));
789 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
790 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
792 if ( ret.first && ret.second )
798 template <typename Q, typename Compare>
799 bool find_at( head_type& refHead, Q const& key, Compare cmp )
801 return base_class::find_at( refHead, key, cmp );
804 template <typename Q, typename Compare, typename Func>
805 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
807 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
810 template <typename Q, typename Compare>
811 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
813 return base_class::get_at( refHead, guard, key, cmp );
819 }} // namespace cds::container
821 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H