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
285 /// Returns a forward const iterator addressing the first element in a list
286 const_iterator cbegin() const
288 const_iterator it( const_cast<node_type *>(&m_Head) );
289 ++it; // skip dummy head
293 /// Returns an const iterator that addresses the location succeeding the last element in a list
294 const_iterator end() const
298 const_iterator cend() const
300 return const_iterator( const_cast<node_type *>(&m_Tail) );
304 /// Default constructor initializes empty list
307 static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
308 m_Head.m_pNext.store( &m_Tail, memory_model::memory_order_relaxed );
311 /// Destroys the list object
315 assert( m_Head.m_pNext.load(memory_model::memory_order_relaxed) == &m_Tail );
316 m_Head.m_pNext.store( nullptr, memory_model::memory_order_relaxed );
321 The function inserts \p val in the list if the list does not contain
322 an item with key equal to \p val.
324 Returns \p true if \p val is linked into the list, \p false otherwise.
326 bool insert( value_type& val )
328 return insert_at( &m_Head, val );
331 /// Ensures that the \p item exists in the list
333 The operation performs inserting or changing data with lock-free manner.
335 If the item \p val not found in the list, then \p val is inserted into the list.
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 ensure function
347 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
348 refers to the same thing.
350 The functor may change non-key fields of the \p item.
351 While the functor \p f is calling the item \p item is locked.
353 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
354 \p second is true if new item has been added or \p false if the item with \p key
355 already is in the list.
358 template <typename Func>
359 std::pair<bool, bool> ensure( value_type& val, Func func )
361 return ensure_at( &m_Head, val, func );
364 /// Finds the key \p key
365 /** \anchor cds_intrusive_LazyList_nogc_find_func
366 The function searches the item with key equal to \p key
367 and calls the functor \p f for item found.
368 The interface of \p Func functor is:
371 void operator()( value_type& item, Q& key );
374 where \p item is the item found, \p key is the <tt>find</tt> function argument.
376 The functor may change non-key fields of \p item.
377 While the functor \p f is calling the item found \p item is locked.
379 The function returns \p true if \p key is found, \p false otherwise.
381 template <typename Q, typename Func>
382 bool find( Q& key, Func f )
384 return find_at( &m_Head, key, key_comparator(), f );
387 /// Finds the key \p key using \p pred predicate for searching
389 The function is an analog of \ref cds_intrusive_LazyList_nogc_find_func "find(Q&, Func)"
390 but \p pred is used for key comparing.
391 \p Less functor has the interface like \p std::less.
392 \p pred must imply the same element order as the comparator used for building the list.
394 template <typename Q, typename Less, typename Func>
395 bool find_with( Q& key, Less pred, Func f )
397 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
400 /// Finds the key \p key
401 /** \anchor cds_intrusive_LazyList_nogc_find_val
402 The function searches the item with key equal to \p key
403 and returns pointer to value found or \p nullptr.
405 template <typename Q>
406 value_type * find( Q const& key )
408 return find_at( &m_Head, key, key_comparator() );
411 /// Finds the key \p key using \p pred predicate for searching
413 The function is an analog of \ref cds_intrusive_LazyList_nogc_find_val "find(Q const&)"
414 but \p pred is used for key comparing.
415 \p Less functor has the interface like \p std::less.
416 \p pred must imply the same element order as the comparator used for building the list.
418 template <typename Q, typename Less>
419 value_type * find_with( Q const & key, Less pred )
421 return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>() );
426 The function unlink all items from the list.
427 For each unlinked item the item disposer \p disp is called after unlinking.
429 This function is not thread-safe.
431 template <typename Disposer>
432 void clear( Disposer disp )
434 node_type * pHead = m_Head.m_pNext.exchange( &m_Tail, memory_model::memory_order_release );
436 while ( pHead != &m_Tail ) {
437 node_type * p = pHead->m_pNext.load(memory_model::memory_order_relaxed);
438 dispose_node( pHead, disp );
443 /// Clears the list using default disposer
445 The function clears the list using default (provided in class template) disposer functor.
452 /// Checks if the list is empty
455 return m_Head.m_pNext.load(memory_model::memory_order_relaxed) == &m_Tail;
458 /// Returns list's item count
460 The value returned depends on opt::item_counter option. For atomicity::empty_item_counter,
461 this function always returns 0.
463 <b>Warning</b>: even if you use real item counter and it returns 0, this fact is not mean that the list
464 is empty. To check list emptyness use \ref empty() method.
468 return m_ItemCounter.value();
473 // split-list support
474 bool insert_aux_node( node_type * pNode )
476 return insert_aux_node( &m_Head, pNode );
479 // split-list support
480 bool insert_aux_node( node_type * pHead, node_type * pNode )
482 assert( pHead != nullptr );
483 assert( pNode != nullptr );
485 // Hack: convert node_type to value_type.
486 // In principle, auxiliary node can be non-reducible to value_type
487 // We assume that comparator can correctly distinguish aux and regular node.
488 return insert_at( pHead, *node_traits::to_value_ptr( pNode ) );
491 bool insert_at( node_type * pHead, value_type& val )
493 link_checker::is_empty( node_traits::to_node_ptr( val ) );
498 search( pHead, val, pos, key_comparator() );
500 auto_lock_position alp( pos );
501 if ( validate( pos.pPred, pos.pCur )) {
502 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
503 // failed: key already in list
507 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
516 iterator insert_at_( node_type * pHead, value_type& val )
518 if ( insert_at( pHead, val ))
519 return iterator( node_traits::to_node_ptr( val ));
524 template <typename Func>
525 std::pair<iterator, bool> ensure_at_( node_type * pHead, value_type& val, Func func )
531 search( pHead, val, pos, key_comparator() );
533 auto_lock_position alp( pos );
534 if ( validate( pos.pPred, pos.pCur )) {
535 if ( pos.pCur != &m_Tail && cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 ) {
536 // key already in the list
538 func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
539 return std::make_pair( iterator( pos.pCur ), false );
543 link_checker::is_empty( node_traits::to_node_ptr( val ) );
545 link_node( node_traits::to_node_ptr( val ), pos.pPred, pos.pCur );
546 func( true, val, val );
548 return std::make_pair( iterator( node_traits::to_node_ptr( val )), true );
555 template <typename Func>
556 std::pair<bool, bool> ensure_at( node_type * pHead, value_type& val, Func func )
558 std::pair<iterator, bool> ret = ensure_at_( pHead, val, func );
559 return std::make_pair( ret.first != end(), ret.second );
562 template <typename Q, typename Compare, typename Func>
563 bool find_at( node_type * pHead, Q& val, Compare cmp, Func f )
567 search( pHead, val, pos, cmp );
568 if ( pos.pCur != &m_Tail ) {
569 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
570 if ( cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
572 f( *node_traits::to_value_ptr( *pos.pCur ), val );
579 template <typename Q, typename Compare>
580 value_type * find_at( node_type * pHead, Q& val, Compare cmp)
582 iterator it = find_at_( pHead, val, cmp );
588 template <typename Q, typename Compare>
589 iterator find_at_( node_type * pHead, Q& val, Compare cmp)
593 search( pHead, val, pos, cmp );
594 if ( pos.pCur != &m_Tail ) {
595 std::unique_lock< typename node_type::lock_type> al( pos.pCur->m_Lock );
596 if ( cmp( *node_traits::to_value_ptr( *pos.pCur ), val ) == 0 )
598 return iterator( pos.pCur );
608 template <typename Q, typename Compare>
609 void search( node_type * pHead, const Q& key, position& pos, Compare cmp )
611 const node_type * pTail = &m_Tail;
613 node_type * pCur = pHead;
614 node_type * pPrev = pHead;
616 while ( pCur != pTail && ( pCur == pHead || cmp( *node_traits::to_value_ptr( *pCur ), key ) < 0 )) {
618 pCur = pCur->m_pNext.load(memory_model::memory_order_acquire);
625 static bool validate( node_type * pPred, node_type * pCur )
627 return pPred->m_pNext.load(memory_model::memory_order_acquire) == pCur;
633 }} // namespace cds::intrusive
635 #endif // #ifndef __CDS_INTRUSIVE_LAZY_LIST_NOGC_H