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/
9 Redistribution and use in source and binary forms, with or without
10 modification, are permitted provided that the following conditions are met:
12 * Redistributions of source code must retain the above copyright notice, this
13 list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
16 this list of conditions and the following disclaimer in the documentation
17 and/or other materials provided with the distribution.
19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
23 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
26 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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
140 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
144 typedef typename base_class::value_type node_type;
145 typedef typename maker::cxx_allocator cxx_allocator;
146 typedef typename maker::node_deallocator node_deallocator;
147 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
149 typedef typename base_class::atomic_node_ptr head_type;
154 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
158 static value_type& node_to_value( node_type& n )
162 static value_type const& node_to_value( node_type const& n )
167 template <typename Q>
168 static node_type * alloc_node( Q const& v )
170 return cxx_allocator().New( v );
173 template <typename... Args>
174 static node_type * alloc_node( Args&&... args )
176 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
179 static void free_node( node_type * pNode )
181 cxx_allocator().Delete( pNode );
184 struct node_disposer {
185 void operator()( node_type * pNode )
190 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
194 return base_class::m_pHead;
197 head_type const& head() const
199 return base_class::m_pHead;
205 template <bool IsConst>
206 class iterator_type: protected base_class::template iterator_type<IsConst>
208 typedef typename base_class::template iterator_type<IsConst> iterator_base;
210 iterator_type( head_type const& pNode )
211 : iterator_base( pNode )
214 friend class MichaelList;
217 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
218 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
223 iterator_type( iterator_type const& src )
224 : iterator_base( src )
227 value_ptr operator ->() const
229 typename iterator_base::value_ptr p = iterator_base::operator ->();
230 return p ? &(p->m_Value) : nullptr;
233 value_ref operator *() const
235 return (iterator_base::operator *()).m_Value;
239 iterator_type& operator ++()
241 iterator_base::operator ++();
246 bool operator ==(iterator_type<C> const& i ) const
248 return iterator_base::operator ==(i);
251 bool operator !=(iterator_type<C> const& i ) const
253 return iterator_base::operator !=(i);
259 ///@name Forward iterators (only for debugging purpose)
263 The forward iterator for Michael's list has some features:
264 - it has no post-increment operator
265 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
266 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
267 may be thrown if a limit of guard count per thread is exceeded.
268 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
269 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
270 deleting operations it is no guarantee that you iterate all item in the list.
271 Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread.
273 @warning Use this iterator on the concurrent container for debugging purpose only.
275 typedef iterator_type<false> iterator;
277 /// Const forward iterator
279 For iterator's features and requirements see \ref iterator
281 typedef iterator_type<true> const_iterator;
283 /// Returns a forward iterator addressing the first element in a list
285 For empty list \code begin() == end() \endcode
289 return iterator( head() );
292 /// Returns an iterator that addresses the location succeeding the last element in a list
294 Do not use the value returned by <tt>end</tt> function to access any item.
295 Internally, <tt>end</tt> returning value equals to \p nullptr.
297 The returned value can be used only to control reaching the end of the list.
298 For empty list \code begin() == end() \endcode
305 /// Returns a forward const iterator addressing the first element in a list
306 const_iterator begin() const
308 return const_iterator( head() );
311 /// Returns a forward const iterator addressing the first element in a list
312 const_iterator cbegin() const
314 return const_iterator( head() );
317 /// Returns an const iterator that addresses the location succeeding the last element in a list
318 const_iterator end() const
320 return const_iterator();
323 /// Returns an const iterator that addresses the location succeeding the last element in a list
324 const_iterator cend() const
326 return const_iterator();
331 /// Default constructor
333 Initialize empty list
349 The function creates a node with copy of \p val value
350 and then inserts the node created into the list.
352 The type \p Q should contain least the complete key of the node.
353 The object of \ref value_type should be constructible from \p val of type \p Q.
354 In trivial case, \p Q is equal to \ref value_type.
356 Returns \p true if inserting successful, \p false otherwise.
358 template <typename Q>
359 bool insert( Q const& val )
361 return insert_at( head(), val );
366 This function inserts new node with default-constructed value and then it calls
367 \p func functor with signature
368 \code void func( value_type& itemValue ) ;\endcode
370 The argument \p itemValue of user-defined functor \p func is the reference
371 to the list's item inserted. User-defined functor \p func should guarantee that during changing
372 item's value no any other changes could be made on this list's item by concurrent threads.
373 The user-defined functor is called only if inserting is success.
375 The type \p Q should contain the complete key of the node.
376 The object of \p value_type should be constructible from \p key of type \p Q.
378 The function allows to split creating of new item into two part:
379 - create item from \p key with initializing key-fields only;
380 - insert new item into the list;
381 - if inserting is successful, initialize non-key fields of item by calling \p func functor
383 The method can be useful if complete initialization of object of \p value_type is heavyweight and
384 it is preferable that the initialization should be completed only if inserting is successful.
386 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
388 template <typename Q, typename Func>
389 bool insert( Q const& key, Func func )
391 return insert_at( head(), key, func );
394 /// Updates data by \p key
396 The operation performs inserting or replacing the element with lock-free manner.
398 If the \p key not found in the list, then the new item created from \p key
399 will be inserted iff \p bAllowInsert is \p true.
400 Otherwise, if \p key is found, the functor \p func is called with item found.
402 The functor \p Func signature is:
405 void operator()( bool bNew, value_type& item, Q const& val );
410 - \p bNew - \p true if the item has been inserted, \p false otherwise
411 - \p item - item of the list
412 - \p val - argument \p key passed into the \p %update() function
414 The functor may change non-key fields of the \p item; however, \p func must guarantee
415 that during changing no any other modifications could be made on this item by concurrent threads.
417 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
418 \p second is true if new item has been added or \p false if the item with \p key
421 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
423 template <typename Q, typename Func>
424 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
426 return update_at( head(), key, func, bAllowInsert );
429 template <typename Q, typename Func>
430 CDS_DEPRECATED("ensure() is deprecated, use update()")
431 std::pair<bool, bool> ensure( Q const& key, Func func )
433 return update( key, func );
437 /// Inserts data of type \p value_type constructed with <tt>std::forward<Args>(args)...</tt>
439 Returns \p true if inserting successful, \p false otherwise.
441 template <typename... Args>
442 bool emplace( Args&&... args )
444 return emplace_at( head(), std::forward<Args>(args)... );
447 /// Delete \p key from the list
448 /** \anchor cds_nonintrusive_MichealList_hp_erase_val
449 Since the key of MichaelList's item type \p value_type is not explicitly specified,
450 template parameter \p Q sould contain the complete key to search in the list.
451 The list item comparator should be able to compare the type \p value_type
454 Return \p true if key is found and deleted, \p false otherwise
456 template <typename Q>
457 bool erase( Q const& key )
459 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
462 /// Deletes the item from the list using \p pred predicate for searching
464 The function is an analog of \ref cds_nonintrusive_MichealList_hp_erase_val "erase(Q const&)"
465 but \p pred is used for key comparing.
466 \p Less functor has the interface like \p std::less.
467 \p pred must imply the same element order as the comparator used for building the list.
469 template <typename Q, typename Less>
470 bool erase_with( Q const& key, Less pred )
473 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
476 /// Deletes \p key from the list
477 /** \anchor cds_nonintrusive_MichaelList_hp_erase_func
478 The function searches an item with key \p key, calls \p f functor with item found
479 and deletes it. If \p key is not found, the functor is not called.
481 The functor \p Func interface:
484 void operator()(const value_type& val) { ... }
488 Since the key of MichaelList's item type \p value_type is not explicitly specified,
489 template parameter \p Q should contain the complete key to search in the list.
490 The list item comparator should be able to compare the type \p value_type of list item
493 Return \p true if key is found and deleted, \p false otherwise
495 template <typename Q, typename Func>
496 bool erase( Q const& key, Func f )
498 return erase_at( head(), key, intrusive_key_comparator(), f );
501 /// Deletes the item from the list using \p pred predicate for searching
503 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_erase_func "erase(Q const&, Func)"
504 but \p pred is used for key comparing.
505 \p Less functor has the interface like \p std::less.
506 \p pred must imply the same element order as the comparator used for building the list.
508 template <typename Q, typename Less, typename Func>
509 bool erase_with( Q const& key, Less pred, Func f )
512 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
515 /// Extracts the item from the list with specified \p key
516 /** \anchor cds_nonintrusive_MichaelList_hp_extract
517 The function searches an item with key equal to \p key,
518 unlinks it from the list, and returns it as \p guarded_ptr.
519 If \p key is not found the function returns an empty guarded pointer.
521 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
523 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
527 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
531 ord_list::guarded_ptr gp(theList.extract( 5 ));
536 // Destructor of gp releases internal HP guard and frees the item
540 template <typename Q>
541 guarded_ptr extract( Q const& key )
544 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
548 /// Extracts the item from the list with comparing functor \p pred
550 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_extract "extract(Q const&)"
551 but \p pred predicate is used for key comparing.
553 \p Less functor has the semantics like \p std::less but it should accept arguments of type \p value_type and \p Q
555 \p pred must imply the same element order as the comparator used for building the list.
557 template <typename Q, typename Less>
558 guarded_ptr extract_with( Q const& key, Less pred )
562 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
566 /// Checks whether the list contains \p key
568 The function searches the item with key equal to \p key
569 and returns \p true if it is found, and \p false otherwise.
571 template <typename Q>
572 bool contains( Q const& key )
574 return find_at( head(), key, intrusive_key_comparator() );
577 template <typename Q>
578 CDS_DEPRECATED("deprecated, use contains()")
579 bool find( Q const& key )
581 return contains( key );
585 /// Checks whether the list contains \p key using \p pred predicate for searching
587 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
588 \p Less functor has the interface like \p std::less.
589 \p pred must imply the same element order as the comparator used for building the list.
591 template <typename Q, typename Less>
592 bool contains( Q const& key, Less pred )
595 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
598 template <typename Q, typename Less>
599 CDS_DEPRECATED("deprecated, use contains()")
600 bool find_with( Q const& key, Less pred )
602 return contains( key, pred );
606 /// Finds \p key and perform an action with it
607 /** \anchor cds_nonintrusive_MichaelList_hp_find_func
608 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
609 The interface of \p Func functor is:
612 void operator()( value_type& item, Q& key );
615 where \p item is the item found, \p key is the <tt>find</tt> function argument.
617 The functor may change non-key fields of \p item. Note that the function is only guarantee
618 that \p item cannot be deleted during functor is executing.
619 The function does not serialize simultaneous access to the list \p item. If such access is
620 possible you must provide your own synchronization schema to exclude unsafe item modifications.
622 The function returns \p true if \p key is found, \p false otherwise.
624 template <typename Q, typename Func>
625 bool find( Q& key, Func f )
627 return find_at( head(), key, intrusive_key_comparator(), f );
630 template <typename Q, typename Func>
631 bool find( Q const& key, Func f )
633 return find_at( head(), key, intrusive_key_comparator(), f );
637 /// Finds \p key using \p pred predicate for searching
639 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_find_func "find(Q&, Func)"
640 but \p pred is used for key comparing.
641 \p Less functor has the interface like \p std::less.
642 \p pred must imply the same element order as the comparator used for building the list.
644 template <typename Q, typename Less, typename Func>
645 bool find_with( Q& key, Less pred, Func f )
648 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
651 template <typename Q, typename Less, typename Func>
652 bool find_with( Q const& key, Less pred, Func f )
655 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
659 /// Finds \p key and return the item found
660 /** \anchor cds_nonintrusive_MichaelList_hp_get
661 The function searches the item with key equal to \p key
662 and returns it as \p guarded_ptr.
663 If \p key is not found the function returns an empty guarded pointer.
665 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
669 typedef cds::container::MichaelList< cds::gc::HP, foo, my_traits > ord_list;
673 ord_list::guarded_ptr gp(theList.get( 5 ));
678 // Destructor of guarded_ptr releases internal HP guard and frees the item
682 Note the compare functor specified for class \p Traits template parameter
683 should accept a parameter of type \p Q that can be not the same as \p value_type.
685 template <typename Q>
686 guarded_ptr get( Q const& key )
689 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
693 /// Finds \p key and return the item found
695 The function is an analog of \ref cds_nonintrusive_MichaelList_hp_get "get( Q const&)"
696 but \p pred is used for comparing the keys.
698 \p Less functor has the semantics like \p std::less but should accept arguments of type \p value_type and \p Q
700 \p pred must imply the same element order as the comparator used for building the list.
702 template <typename Q, typename Less>
703 guarded_ptr get_with( Q const& key, Less pred )
707 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
711 /// Check if the list is empty
714 return base_class::empty();
717 /// Returns list's item count
719 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
720 this function always returns 0.
722 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
723 is empty. To check list emptyness use \p empty() method.
727 return base_class::size();
738 bool insert_node( node_type * pNode )
740 return insert_node_at( head(), pNode );
743 bool insert_node_at( head_type& refHead, node_type * pNode )
746 scoped_node_ptr p(pNode);
747 if ( base_class::insert_at( refHead, *pNode )) {
755 template <typename Q>
756 bool insert_at( head_type& refHead, Q const& val )
758 return insert_node_at( refHead, alloc_node( val ));
761 template <typename Q, typename Func>
762 bool insert_at( head_type& refHead, Q const& key, Func f )
764 scoped_node_ptr pNode( alloc_node( key ));
766 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
773 template <typename... Args>
774 bool emplace_at( head_type& refHead, Args&&... args )
776 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
779 template <typename Q, typename Compare, typename Func>
780 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
782 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
785 template <typename Q, typename Compare>
786 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
788 return base_class::extract_at( refHead, guard, key, cmp );
791 template <typename Q, typename Func>
792 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
794 scoped_node_ptr pNode( alloc_node( key ));
796 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
797 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
799 if ( ret.first && ret.second )
805 template <typename Q, typename Compare>
806 bool find_at( head_type& refHead, Q const& key, Compare cmp )
808 return base_class::find_at( refHead, key, cmp );
811 template <typename Q, typename Compare, typename Func>
812 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
814 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
817 template <typename Q, typename Compare>
818 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
820 return base_class::get_at( refHead, guard, key, cmp );
826 }} // namespace cds::container
828 #endif // #ifndef CDSLIB_CONTAINER_IMPL_MICHAEL_LIST_H