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_INTRUSIVE_MICHAEL_LIST_NOGC_H
32 #define CDSLIB_INTRUSIVE_MICHAEL_LIST_NOGC_H
34 #include <cds/intrusive/details/michael_list_base.h>
35 #include <cds/gc/nogc.h>
36 #include <cds/details/make_const_type.h>
39 namespace cds { namespace intrusive {
41 namespace michael_list {
45 - Tag - a tag used to distinguish between different implementation
47 template <typename Tag>
48 struct node<gc::nogc, Tag>
50 typedef gc::nogc gc ; ///< Garbage collector
51 typedef Tag tag ; ///< tag
53 typedef atomics::atomic< node * > atomic_ptr ; ///< atomic marked pointer
55 atomic_ptr m_pNext ; ///< pointer to the next node in the container
61 } // namespace michael_list
63 /// Michael's lock-free ordered single-linked list (template specialization for gc::nogc)
64 /** @ingroup cds_intrusive_list
65 \anchor cds_intrusive_MichaelList_nogc
67 This specialization is intended for so-called append-only usage when no item
68 reclamation may be performed. The class does not support item removal.
70 See \ref cds_intrusive_MichaelList_hp "MichaelList" for description of template parameters.
72 template < typename T,
73 #ifdef CDS_DOXYGEN_INVOKED
74 class Traits = michael_list::traits
79 class MichaelList<gc::nogc, T, Traits>
82 typedef gc::nogc gc; ///< Garbage collector
83 typedef T value_type; ///< type of value to be stored in the queue
84 typedef Traits traits; ///< List traits
86 typedef typename traits::hook hook; ///< hook type
87 typedef typename hook::node_type node_type; ///< node type
89 # ifdef CDS_DOXYGEN_INVOKED
90 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
92 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
95 typedef typename traits::disposer disposer; ///< disposer used
96 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
97 typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
99 typedef typename traits::back_off back_off; ///< back-off strategy
100 typedef typename traits::item_counter item_counter; ///< Item counting policy used
101 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
104 // Rebind traits (split-list support)
105 template <typename... Options>
106 struct rebind_traits {
110 , typename cds::opt::make_options< traits, Options...>::type
116 typedef typename node_type::atomic_ptr atomic_node_ptr ; ///< Atomic node pointer
117 typedef atomic_node_ptr auxiliary_head ; ///< Auxiliary head type (for split-list support)
119 atomic_node_ptr m_pHead; ///< Head pointer
120 item_counter m_ItemCounter; ///< Item counter
123 /// Position pointer for item search
125 atomic_node_ptr * pPrev ; ///< Previous node
126 node_type * pCur ; ///< Current node
127 node_type * pNext ; ///< Next node
133 static void clear_links( node_type * pNode )
135 pNode->m_pNext.store( nullptr, memory_model::memory_order_release );
138 template <class Disposer>
139 static void dispose_node( node_type * pNode, Disposer disp )
141 clear_links( pNode );
142 disp( node_traits::to_value_ptr( *pNode ));
145 template <class Disposer>
146 static void dispose_value( value_type& val, Disposer disp )
148 dispose_node( node_traits::to_node_ptr( val ), disp );
151 static bool link_node( node_type * pNode, position& pos )
153 assert( pNode != nullptr );
154 link_checker::is_empty( pNode );
156 pNode->m_pNext.store( pos.pCur, memory_model::memory_order_relaxed );
157 return pos.pPrev->compare_exchange_strong( pos.pCur, pNode, memory_model::memory_order_release, atomics::memory_order_relaxed );
163 template <bool IsConst>
166 friend class MichaelList;
167 value_type * m_pNode;
172 node_type * pNode = node_traits::to_node_ptr( *m_pNode )->m_pNext.load(memory_model::memory_order_acquire);
174 m_pNode = node_traits::to_value_ptr( *pNode );
181 explicit iterator_type( node_type * pNode)
184 m_pNode = node_traits::to_value_ptr( *pNode );
188 explicit iterator_type( atomic_node_ptr const& refNode)
190 node_type * pNode = refNode.load(memory_model::memory_order_relaxed);
192 m_pNode = node_traits::to_value_ptr( *pNode );
198 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
199 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
205 iterator_type( const iterator_type& src )
206 : m_pNode( src.m_pNode )
209 value_ptr operator ->() const
214 value_ref operator *() const
216 assert( m_pNode != nullptr );
221 iterator_type& operator ++()
228 iterator_type operator ++(int)
230 iterator_type i(*this);
235 iterator_type& operator = (const iterator_type& src)
237 m_pNode = src.m_pNode;
242 bool operator ==(iterator_type<C> const& i ) const
244 return m_pNode == i.m_pNode;
247 bool operator !=(iterator_type<C> const& i ) const
249 return m_pNode != i.m_pNode;
256 typedef iterator_type<false> iterator;
257 /// Const forward iterator
258 typedef iterator_type<true> const_iterator;
260 /// Returns a forward iterator addressing the first element in a list
262 For empty list \code begin() == end() \endcode
266 return iterator(m_pHead.load(memory_model::memory_order_relaxed) );
269 /// Returns an iterator that addresses the location succeeding the last element in a list
271 Do not use the value returned by <tt>end</tt> function to access any item.
272 Internally, <tt>end</tt> returning value equals to \p nullptr.
274 The returned value can be used only to control reaching the end of the list.
275 For empty list \code begin() == end() \endcode
282 /// Returns a forward const iterator addressing the first element in a list
283 const_iterator begin() const
285 return const_iterator(m_pHead.load(memory_model::memory_order_relaxed) );
287 /// Returns a forward const iterator addressing the first element in a list
288 const_iterator cbegin() const
290 return const_iterator(m_pHead.load(memory_model::memory_order_relaxed) );
293 /// Returns an const iterator that addresses the location succeeding the last element in a list
294 const_iterator end() const
296 return const_iterator();
298 /// Returns an const iterator that addresses the location succeeding the last element in a list
299 const_iterator cend() const
301 return const_iterator();
305 /// Default constructor initializes empty list
309 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
312 /// Destroys the list objects
320 The function inserts \p val in the list if the list does not contain
321 an item with key equal to \p val.
323 Returns \p true if \p val is linked into the list, \p false otherwise.
325 bool insert( value_type& val )
327 return insert_at( m_pHead, val );
332 The operation performs inserting or changing data with lock-free manner.
334 If the item \p val not found in the list, then \p val is inserted into the list
335 iff \p bAllowInsert is \p true.
336 Otherwise, the functor \p func is called with item found.
337 The functor signature is:
340 void operator()( bool bNew, value_type& item, value_type& val );
344 - \p bNew - \p true if the item has been inserted, \p false otherwise
345 - \p item - item of the list
346 - \p val - argument \p val passed into the \p update() function
347 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
348 refer to the same thing.
350 The functor may change non-key fields of the \p item; however, \p func must guarantee
351 that during changing no any other modifications could be made on this item by concurrent threads.
353 Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successfull,
354 \p second is \p true if new item has been added or \p false if the item with \p key
355 already is in the list.
357 template <typename Func>
358 std::pair<bool, bool> update( value_type& val, Func func, bool bAllowInsert = true )
360 return update_at( m_pHead, val, func, bAllowInsert );
363 template <typename Func>
364 CDS_DEPRECATED("ensure() is deprecated, use update()")
365 std::pair<bool, bool> ensure( value_type& val, Func func )
367 return update( val, func );
371 /// Finds the key \p val
372 /** \anchor cds_intrusive_MichaelList_nogc_find_func
373 The function searches the item with key equal to \p key
374 and calls the functor \p f for item found.
375 The interface of \p Func functor is:
378 void operator()( value_type& item, Q& key );
381 where \p item is the item found, \p key is the <tt>find</tt> function argument.
383 The functor can change non-key fields of \p item.
384 The function \p find does not serialize simultaneous access to the list \p item. If such access is
385 possible you must provide your own synchronization schema to exclude unsafe item modifications.
387 The function returns \p true if \p val is found, \p false otherwise.
389 template <typename Q, typename Func>
390 bool find( Q& key, Func f )
392 return find_at( m_pHead, key, key_comparator(), f );
395 template <typename Q, typename Func>
396 bool find( Q const& key, Func f )
398 return find_at( m_pHead, key, key_comparator(), f );
402 /// Finds the key \p key using \p pred predicate for searching
404 The function is an analog of \ref cds_intrusive_MichaelList_nogc_find_func "find(Q&, Func)"
405 but \p pred is used for key comparing.
406 \p Less functor has the interface like \p std::less.
407 \p pred must imply the same element order as the comparator used for building the list.
409 template <typename Q, typename Less, typename Func>
410 bool find_with( Q& key, Less pred, Func f )
413 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
416 template <typename Q, typename Less, typename Func>
417 bool find_with( Q const& key, Less pred, Func f )
420 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
424 /// Checks whether the list contains \p key
426 The function searches the item with key equal to \p key
427 and returns \p true if it is found, and \p false otherwise.
429 template <typename Q>
430 value_type * contains( Q const& key )
432 return find_at( m_pHead, key, key_comparator() );
435 template <typename Q>
436 CDS_DEPRECATED("deprecated, use contains()")
437 value_type * find( Q const& key )
439 return contains( key );
443 /// Checks whether the map contains \p key using \p pred predicate for searching
445 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
446 \p Less functor has the interface like \p std::less.
447 \p Less must imply the same element order as the comparator used for building the list.
449 template <typename Q, typename Less>
450 value_type * contains( Q const& key, Less pred )
453 return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
456 template <typename Q, typename Less>
457 CDS_DEPRECATED("deprecated, use contains()")
458 value_type * find_with( Q const& key, Less pred )
460 return contains( key, pred );
466 The function unlink all items from the list.
468 For each unlinked item the item disposer \p disp is called after unlinking.
470 template <typename Disposer>
471 void clear( Disposer disp )
473 node_type * pHead = m_pHead.load(memory_model::memory_order_relaxed);
474 do {} while ( !m_pHead.compare_exchange_weak( pHead, nullptr, memory_model::memory_order_relaxed ) );
477 node_type * p = pHead->m_pNext.load(memory_model::memory_order_relaxed);
478 dispose_node( pHead, disp );
484 /// Clears the list using default disposer
486 The function clears the list using default (provided in class template) disposer functor.
493 /// Checks if the list is empty
496 return m_pHead.load( memory_model::memory_order_relaxed ) == nullptr;
499 /// Returns list's item count
501 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
502 this function always returns 0.
504 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
505 is empty. To check list emptyness use \p empty() method.
509 return m_ItemCounter.value();
514 // split-list support
515 bool insert_aux_node( node_type * pNode )
517 return insert_aux_node( m_pHead, pNode );
520 // split-list support
521 bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
523 assert( pNode != nullptr );
525 // Hack: convert node_type to value_type.
526 // In principle, auxiliary node can be non-reducible to value_type
527 // We assume that comparator can correctly distinguish aux and regular node.
528 return insert_at( refHead, *node_traits::to_value_ptr( pNode ) );
531 bool insert_at( atomic_node_ptr& refHead, value_type& val )
533 link_checker::is_empty( node_traits::to_node_ptr( val ) );
537 if ( search( refHead, val, key_comparator(), pos ) )
540 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
547 iterator insert_at_( atomic_node_ptr& refHead, value_type& val )
549 if ( insert_at( refHead, val ))
550 return iterator( node_traits::to_node_ptr( val ));
554 template <typename Func>
555 std::pair<iterator, bool> update_at_( atomic_node_ptr& refHead, value_type& val, Func func, bool bAllowInsert )
560 if ( search( refHead, val, key_comparator(), pos ) ) {
561 assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur ) ) == 0 );
563 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
564 return std::make_pair( iterator( pos.pCur ), false );
568 return std::make_pair( end(), false );
570 link_checker::is_empty( node_traits::to_node_ptr( val ) );
572 if ( link_node( node_traits::to_node_ptr( val ), pos ) ) {
574 func( true, val , val );
575 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
581 template <typename Func>
582 std::pair<bool, bool> update_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bAllowInsert )
584 std::pair<iterator, bool> ret = update_at_( refHead, val, func, bAllowInsert );
585 return std::make_pair( ret.first != end(), ret.second );
588 template <typename Q, typename Compare, typename Func>
589 bool find_at( atomic_node_ptr& refHead, Q& val, Compare cmp, Func f )
593 if ( search( refHead, val, cmp, pos ) ) {
594 assert( pos.pCur != nullptr );
595 f( *node_traits::to_value_ptr( *pos.pCur ), val );
601 template <typename Q, typename Compare>
602 value_type * find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
604 iterator it = find_at_( refHead, val, cmp );
610 template <typename Q, typename Compare>
611 iterator find_at_( atomic_node_ptr& refHead, Q const& val, Compare cmp )
615 if ( search( refHead, val, cmp, pos ) ) {
616 assert( pos.pCur != nullptr );
617 return iterator( pos.pCur );
627 template <typename Q, typename Compare >
628 bool search( atomic_node_ptr& refHead, const Q& val, Compare cmp, position& pos )
630 atomic_node_ptr * pPrev;
638 pCur = pPrev->load(memory_model::memory_order_acquire);
649 pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed);
650 if ( pCur->m_pNext.load(memory_model::memory_order_acquire) != pNext ) {
655 if ( pPrev->load(memory_model::memory_order_acquire) != pCur ) {
660 assert( pCur != nullptr );
661 int nCmp = cmp( *node_traits::to_value_ptr( *pCur ), val );
668 pPrev = &( pCur->m_pNext );
675 }} // namespace cds::intrusive
677 #endif // #ifndef CDSLIB_INTRUSIVE_MICHAEL_LIST_NOGC_H