3 #ifndef __CDS_INTRUSIVE_LAZY_LIST_NOGC_H
4 #define __CDS_INTRUSIVE_LAZY_LIST_NOGC_H
6 #include <mutex> // unique_lock
7 #include <cds/intrusive/details/lazy_list_base.h>
8 #include <cds/gc/nogc.h>
10 namespace cds { namespace intrusive {
12 /// Lazy list node for \p gc::nogc
15 - Lock - lock type. Default is \p cds::lock::Spin
16 - Tag - a \ref cds_intrusive_hook_tag "tag"
19 #ifdef CDS_DOXYGEN_INVOKED
20 typename Lock = cds::lock::Spin,
21 typename Tag = opt::none
27 struct node<gc::nogc, Lock, Tag>
29 typedef gc::nogc gc; ///< Garbage collector
30 typedef Lock lock_type; ///< Lock type
31 typedef Tag tag; ///< tag
33 atomics::atomic<node *> m_pNext; ///< pointer to the next node in the list
34 mutable lock_type m_Lock; ///< Node lock
40 } // namespace lazy_list
43 /// Lazy ordered single-linked list (template specialization for \p gc::nogc)
44 /** @ingroup cds_intrusive_list
45 \anchor cds_intrusive_LazyList_nogc
47 This specialization is append-only list when no item
48 reclamation may be performed. The class does not support deleting of list item.
50 See \ref cds_intrusive_LazyList_hp "LazyList" for description of template parameters.
54 #ifdef CDS_DOXYGEN_INVOKED
55 ,class Traits = lazy_list::traits
60 class LazyList<gc::nogc, T, Traits>
63 typedef gc::nogc gc; ///< Garbage collector
64 typedef T value_type; ///< type of value stored in the list
65 typedef Traits traits; ///< Traits template parameter
67 typedef typename traits::hook hook; ///< hook type
68 typedef typename hook::node_type node_type; ///< node type
70 # ifdef CDS_DOXYGEN_INVOKED
71 typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter.
73 typedef typename opt::details::make_comparator< value_type, traits >::type key_comparator;
75 typedef typename traits::back_off back_off; ///< Back-off strategy
76 typedef typename traits::disposer disposer; ///< disposer
77 typedef typename get_node_traits< value_type, node_type, hook>::type node_traits; ///< node traits
78 typedef typename lazy_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
80 typedef typename traits::item_counter item_counter; ///< Item counting policy used
81 typedef typename traits::memory_model memory_model; ///< C++ memory ordering (see lazy_list::traits::memory_model)
84 // Rebind traits (split-list support)
85 template <typename... Options>
86 struct rebind_traits {
90 , typename cds::opt::make_options< traits, Options...>::type
96 typedef node_type * auxiliary_head ; ///< Auxiliary head type (for split-list support)
99 node_type m_Head; ///< List head (dummy node)
100 node_type m_Tail; ///< List tail (dummy node)
101 item_counter m_ItemCounter; ///< Item counter
105 /// Position pointer for item search
107 node_type * pPred ; ///< Previous node
108 node_type * pCur ; ///< Current node
110 /// Locks nodes \p pPred and \p pCur
113 pPred->m_Lock.lock();
117 /// Unlocks nodes \p pPred and \p pCur
120 pCur->m_Lock.unlock();
121 pPred->m_Lock.unlock();
125 class auto_lock_position {
128 auto_lock_position( position& pos )
133 ~auto_lock_position()
142 void clear_links( node_type * pNode )
144 pNode->m_pNext.store( nullptr, memory_model::memory_order_relaxed );
147 template <class Disposer>
148 void dispose_node( node_type * pNode, Disposer disp )
150 clear_links( pNode );
151 disp( node_traits::to_value_ptr( *pNode ));
154 template <class Disposer>
155 void dispose_value( value_type& val, Disposer disp )
157 dispose_node( node_traits::to_node_ptr( val ), disp );
160 void link_node( node_type * pNode, node_type * pPred, node_type * pCur )
162 assert( pPred->m_pNext.load(memory_model::memory_order_relaxed) == pCur );
164 pNode->m_pNext.store( pCur, memory_model::memory_order_release );
165 pPred->m_pNext.store( pNode, memory_model::memory_order_release );
171 template <bool IsConst>
174 friend class LazyList;
177 value_type * m_pNode;
181 assert( m_pNode != nullptr );
183 node_type * pNode = node_traits::to_node_ptr( m_pNode );
184 node_type * pNext = pNode->m_pNext.load(memory_model::memory_order_relaxed);
185 if ( pNext != nullptr )
186 m_pNode = node_traits::to_value_ptr( pNext );
189 iterator_type( node_type * pNode )
191 m_pNode = node_traits::to_value_ptr( pNode );
195 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
196 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
202 iterator_type( const iterator_type& src )
203 : m_pNode( src.m_pNode )
206 value_ptr operator ->() const
211 value_ref operator *() const
213 assert( m_pNode != nullptr );
218 iterator_type& operator ++()
225 iterator_type operator ++(int)
227 iterator_type i(*this);
232 iterator_type& operator = (const iterator_type& src)
234 m_pNode = src.m_pNode;
239 bool operator ==(iterator_type<C> const& i ) const
241 return m_pNode == i.m_pNode;
244 bool operator !=(iterator_type<C> const& i ) const
246 return m_pNode != i.m_pNode;
253 typedef iterator_type<false> iterator;
254 /// Const forward iterator
255 typedef iterator_type<true> const_iterator;
257 /// Returns a forward iterator addressing the first element in a list
259 For empty list \code begin() == end() \endcode
263 iterator it( &m_Head );
264 ++it ; // skip dummy head
268 /// Returns an iterator that addresses the location succeeding the last element in a list
270 Do not use the value returned by <tt>end</tt> function to access any item.
272 The returned value can be used only to control reaching the end of the list.
273 For empty list \code begin() == end() \endcode
277 return iterator( &m_Tail );
280 /// Returns a forward const iterator addressing the first element in a list
281 const_iterator begin() const
283 const_iterator it( const_cast<node_type *>( &m_Head ));
284 ++it ; // skip dummy head
288 /// Returns an const iterator that addresses the location succeeding the last element in a list
289 const_iterator end() const
291 return const_iterator( const_cast<node_type *>( &m_Tail ));
295 /// Default constructor initializes empty list
298 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
299 m_Head.m_pNext.store( &m_Tail, memory_model::memory_order_relaxed );
302 /// Destroys the list object
306 assert( m_Head.m_pNext.load(memory_model::memory_order_relaxed) == &m_Tail );
307 m_Head.m_pNext.store( nullptr, memory_model::memory_order_relaxed );
312 The function inserts \p val in the list if the list does not contain
313 an item with key equal to \p val.
315 Returns \p true if \p val is linked into the list, \p false otherwise.
317 bool insert( value_type& val )
319 return insert_at( &m_Head, val );
322 /// Ensures that the \p item exists in the list
324 The operation performs inserting or changing data with lock-free manner.
326 If the item \p val not found in the list, then \p val is inserted into the list.
327 Otherwise, the functor \p func is called with item found.
328 The functor signature is:
331 void operator()( bool bNew, value_type& item, value_type& val );
335 - \p bNew - \p true if the item has been inserted, \p false otherwise
336 - \p item - item of the list
337 - \p val - argument \p val passed into the \p ensure function
338 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
339 refers to the same thing.
341 The functor may change non-key fields of the \p item.
342 While the functor \p f is calling the item \p item is locked.
344 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
345 \p second is true if new item has been added or \p false if the item with \p key
346 already is in the list.
349 template <typename Func>
350 std::pair<bool, bool> ensure( value_type& val, Func func )
352 return ensure_at( &m_Head, val, func );
355 /// Finds the key \p key
356 /** \anchor cds_intrusive_LazyList_nogc_find_func
357 The function searches the item with key equal to \p key
358 and calls the functor \p f for item found.
359 The interface of \p Func functor is:
362 void operator()( value_type& item, Q& key );
365 where \p item is the item found, \p key is the <tt>find</tt> function argument.
367 The functor may change non-key fields of \p item.
368 While the functor \p f is calling the item found \p item is locked.
370 The function returns \p true if \p key is found, \p false otherwise.
372 template <typename Q, typename Func>
373 bool find( Q& key, Func f )
375 return find_at( &m_Head, key, key_comparator(), f );
378 /// Finds the key \p key using \p pred predicate for searching
380 The function is an analog of \ref cds_intrusive_LazyList_nogc_find_func "find(Q&, Func)"
381 but \p pred is used for key comparing.
382 \p Less functor has the interface like \p std::less.
383 \p pred must imply the same element order as the comparator used for building the list.
385 template <typename Q, typename Less, typename Func>
386 bool find_with( Q& key, Less pred, Func f )
388 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
391 /// Finds the key \p key
392 /** \anchor cds_intrusive_LazyList_nogc_find_val
393 The function searches the item with key equal to \p key
394 and returns pointer to value found or \p nullptr.
396 template <typename Q>
397 value_type * find( Q const& key )
399 return find_at( &m_Head, key, key_comparator() );
402 /// Finds the key \p key using \p pred predicate for searching
404 The function is an analog of \ref cds_intrusive_LazyList_nogc_find_val "find(Q const&)"
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>
410 value_type * find_with( Q const & key, Less pred )
412 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>() );
417 The function unlink all items from the list.
418 For each unlinked item the item disposer \p disp is called after unlinking.
420 This function is not thread-safe.
422 template <typename Disposer>
423 void clear( Disposer disp )
425 node_type * pHead = m_Head.m_pNext.exchange( &m_Tail, memory_model::memory_order_release );
427 while ( pHead != &m_Tail ) {
428 node_type * p = pHead->m_pNext.load(memory_model::memory_order_relaxed);
429 dispose_node( pHead, disp );
434 /// Clears the list using default disposer
436 The function clears the list using default (provided in class template) disposer functor.
443 /// Checks if the list is empty
446 return m_Head.m_pNext.load(memory_model::memory_order_relaxed) == &m_Tail;
449 /// Returns list's item count
451 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
452 this function always returns 0.
454 <b>Warning</b>: even if you use real item counter and it returns 0, this fact is not mean that the list
455 is empty. To check list emptyness use \ref empty() method.
459 return m_ItemCounter.value();
464 // split-list support
465 bool insert_aux_node( node_type * pNode )
467 return insert_aux_node( &m_Head, pNode );
470 // split-list support
471 bool insert_aux_node( node_type * pHead, node_type * pNode )
473 assert( pHead != nullptr );
474 assert( pNode != nullptr );
476 // Hack: convert node_type to value_type.
477 // In principle, auxiliary node can be non-reducible to value_type
478 // We assume that comparator can correctly distinguish aux and regular node.
479 return insert_at( pHead, *node_traits::to_value_ptr( pNode ) );
482 bool insert_at( node_type * pHead, value_type& val )
484 link_checker::is_empty( node_traits::to_node_ptr( val ) );
489 search( pHead, val, pos, key_comparator() );
491 auto_lock_position alp( pos );
492 if ( validate( pos.pPred, pos.pCur )) {
493 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
494 // failed: key already in list
498 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
507 iterator insert_at_( node_type * pHead, value_type& val )
509 if ( insert_at( pHead, val ))
510 return iterator( node_traits::to_node_ptr( val ));
515 template <typename Func>
516 std::pair<iterator, bool> ensure_at_( node_type * pHead, value_type& val, Func func )
522 search( pHead, val, pos, key_comparator() );
524 auto_lock_position alp( pos );
525 if ( validate( pos.pPred, pos.pCur )) {
526 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
527 // key already in the list
529 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
530 return std::make_pair( iterator( pos.pCur ), false );
534 link_checker::is_empty( node_traits::to_node_ptr( val ) );
536 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
537 func( true, val, val );
539 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
546 template <typename Func>
547 std::pair<bool, bool> ensure_at( node_type * pHead, value_type& val, Func func )
549 std::pair<iterator, bool> ret = ensure_at_( pHead, val, func );
550 return std::make_pair( ret.first != end(), ret.second );
553 template <typename Q, typename Compare, typename Func>
554 bool find_at( node_type * pHead, Q& val, Compare cmp, Func f )
558 search( pHead, val, pos, cmp );
559 if ( pos.pCur != &m_Tail ) {
560 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
561 if ( cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
563 f( *node_traits::to_value_ptr( *pos.pCur ), val );
570 template <typename Q, typename Compare>
571 value_type * find_at( node_type * pHead, Q& val, Compare cmp)
573 iterator it = find_at_( pHead, val, cmp );
579 template <typename Q, typename Compare>
580 iterator find_at_( node_type * pHead, Q& val, Compare cmp)
584 search( pHead, val, pos, cmp );
585 if ( pos.pCur != &m_Tail ) {
586 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
587 if ( cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
589 return iterator( pos.pCur );
599 template <typename Q, typename Compare>
600 void search( node_type * pHead, const Q& key, position& pos, Compare cmp )
602 const node_type * pTail = &m_Tail;
604 node_type * pCur = pHead;
605 node_type * pPrev = pHead;
607 while ( pCur != pTail && ( pCur == pHead || cmp( *node_traits::to_value_ptr( *pCur ), key ) < 0 )) {
609 pCur = pCur->m_pNext.load(memory_model::memory_order_acquire);
616 static bool validate( node_type * pPred, node_type * pCur )
618 return pPred->m_pNext.load(memory_model::memory_order_acquire) == pCur;
624 }} // namespace cds::intrusive
626 #endif // #ifndef __CDS_INTRUSIVE_LAZY_LIST_NOGC_H