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_LAZY_LIST_H
32 #define CDSLIB_CONTAINER_IMPL_LAZY_LIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
40 /** @ingroup cds_nonintrusive_list
41 @anchor cds_nonintrusive_LazyList_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>.
47 - [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit
48 "A Lazy Concurrent List-Based Set Algorithm"
50 The lazy list is based on an optimistic locking scheme for inserts and removes,
51 eliminating the need to use the equivalent of an atomically markable
52 reference. It also has a novel wait-free membership \p find() operation
53 that does not need to perform cleanup operations and is more efficient.
55 It is non-intrusive version of \p cds::intrusive::LazyList class.
58 - \p GC - garbage collector: \p gc::HP, \p gp::DHP
59 - \p T - type to be stored in the list.
60 - \p Traits - type traits, default is \p lazy_list::traits.
61 It is possible to declare option-based list with \p lazy_list::make_traits metafunction istead of \p Traits template
62 argument. For example, the following traits-based declaration of \p gc::HP lazy list
64 #include <cds/container/lazy_list_hp.h>
65 // Declare comparator for the item
67 int operator ()( int i1, int i2 )
74 struct my_traits: public cds::container::lazy_list::traits
76 typedef my_compare compare;
79 // Declare traits-based list
80 typedef cds::container::LazyList< cds::gc::HP, int, my_traits > traits_based_list;
82 is equal to the following option-based list:
84 #include <cds/container/lazy_list_hp.h>
86 // my_compare is the same
88 // Declare option-based list
89 typedef cds::container::LazyList< cds::gc::HP, int,
90 typename cds::container::lazy_list::make_traits<
91 cds::container::opt::compare< my_compare > // item comparator option
96 Unlike standard container, this implementation does not divide type \p T into key and value part and
97 may be used as main building block for hash set algorithms.
99 The key is a function (or a part) of type \p T, and the comparing function is specified by \p Traits::compare functor
100 or \p Traits::less predicate.
102 \p LazyKVList is a key-value version of lazy non-intrusive list that is closer to the C++ std library approach.
105 There are different specializations of this template for each garbage collecting schema used.
106 You should include appropriate .h-file depending on GC you are using:
107 - for gc::HP: <tt> <cds/container/lazy_list_hp.h> </tt>
108 - for gc::DHP: <tt> <cds/container/lazy_list_dhp.h> </tt>
109 - for \ref cds_urcu_desc "RCU": <tt> <cds/container/lazy_list_rcu.h> </tt>
110 - for gc::nogc: <tt> <cds/container/lazy_list_nogc.h> </tt>
115 #ifdef CDS_DOXYGEN_INVOKED
116 typename Traits = lazy_list::traits
122 #ifdef CDS_DOXYGEN_INVOKED
123 protected intrusive::LazyList< GC, T, Traits >
125 protected details::make_lazy_list< GC, T, Traits >::type
129 typedef details::make_lazy_list< GC, T, Traits > maker;
130 typedef typename maker::type base_class;
134 typedef GC gc; ///< Garbage collector used
135 typedef T value_type; ///< Type of value stored in the list
136 typedef Traits traits; ///< List traits
138 typedef typename base_class::back_off back_off; ///< Back-off strategy used
139 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
140 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
141 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
142 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
146 typedef typename base_class::value_type node_type;
147 typedef typename maker::cxx_allocator cxx_allocator;
148 typedef typename maker::node_deallocator node_deallocator;
149 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
151 typedef typename base_class::node_type head_type;
156 typedef typename gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
160 static value_type& node_to_value( node_type& n )
164 static value_type const& node_to_value( node_type const& n )
172 template <typename Q>
173 static node_type * alloc_node( Q const& v )
175 return cxx_allocator().New( v );
178 template <typename... Args>
179 static node_type * alloc_node( Args&&... args )
181 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
184 static void free_node( node_type * pNode )
186 cxx_allocator().Delete( pNode );
189 struct node_disposer {
190 void operator()( node_type * pNode )
195 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
199 return base_class::m_Head;
202 head_type const& head() const
204 return base_class::m_Head;
209 return base_class::m_Tail;
212 head_type const& tail() const
214 return base_class::m_Tail;
220 template <bool IsConst>
221 class iterator_type: protected base_class::template iterator_type<IsConst>
223 typedef typename base_class::template iterator_type<IsConst> iterator_base;
225 iterator_type( head_type const& pNode )
226 : iterator_base( const_cast<head_type *>( &pNode ))
229 iterator_type( head_type const * pNode )
230 : iterator_base( const_cast<head_type *>( pNode ))
233 friend class LazyList;
236 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
237 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
242 iterator_type( const iterator_type& src )
243 : iterator_base( src )
246 value_ptr operator ->() const
248 typename iterator_base::value_ptr p = iterator_base::operator ->();
249 return p ? &(p->m_Value) : nullptr;
252 value_ref operator *() const
254 return (iterator_base::operator *()).m_Value;
258 iterator_type& operator ++()
260 iterator_base::operator ++();
265 bool operator ==(iterator_type<C> const& i ) const
267 return iterator_base::operator ==(i);
270 bool operator !=(iterator_type<C> const& i ) const
272 return iterator_base::operator !=(i);
280 The forward iterator for lazy list has some features:
281 - it has no post-increment operator
282 - to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator.
283 For some GC (\p gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard"
284 may be thrown if a limit of guard count per thread is exceeded.
285 - The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
286 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
287 deleting operations it is no guarantee that you iterate all item in the list.
289 @warning Use this iterator on the concurrent container for debugging purpose only.
291 typedef iterator_type<false> iterator;
293 /// Const forward iterator
295 For iterator's features and requirements see \ref iterator
297 typedef iterator_type<true> const_iterator;
299 ///@name Forward iterators (only for debugging purpose)
301 /// Returns a forward iterator addressing the first element in a list
303 For empty list \code begin() == end() \endcode
307 iterator it( head() );
308 ++it ; // skip dummy head node
312 /// Returns an iterator that addresses the location succeeding the last element in a list
314 Do not use the value returned by <tt>end</tt> function to access any item.
316 The returned value can be used only to control reaching the end of the list.
317 For empty list \code begin() == end() \endcode
321 return iterator( tail() );
324 /// Returns a forward const iterator addressing the first element in a list
325 const_iterator begin() const
327 const_iterator it( head() );
328 ++it ; // skip dummy head node
332 /// Returns a forward const iterator addressing the first element in a list
333 const_iterator cbegin() const
335 const_iterator it( head() );
336 ++it ; // skip dummy head node
340 /// Returns an const iterator that addresses the location succeeding the last element in a list
341 const_iterator end() const
343 return const_iterator( tail() );
346 /// Returns an const iterator that addresses the location succeeding the last element in a list
347 const_iterator cend() const
349 return const_iterator( tail() );
354 /// Default constructor
358 /// Destructor clears the list
366 The function creates a node with copy of \p val value
367 and then inserts the node created into the list.
369 The type \p Q should contain as minimum the complete key of the node.
370 The object of \ref value_type should be constructible from \p val of type \p Q.
371 In trivial case, \p Q is equal to \ref value_type.
373 Returns \p true if inserting successful, \p false otherwise.
375 template <typename Q>
376 bool insert( Q const& val )
378 return insert_at( head(), val );
383 This function inserts new node with default-constructed value and then it calls
384 \p func functor with signature
385 \code void func( value_type& item ) ;\endcode
387 The argument \p item of user-defined functor \p func is the reference
388 to the list's item inserted.
389 When \p func is called it has exclusive access to the item.
390 The user-defined functor is called only if the inserting is success.
392 The type \p Q should contain the complete key of the node.
393 The object of \p value_type should be constructible from \p key of type \p Q.
395 The function allows to split creating of new item into two part:
396 - create item from \p key with initializing key-fields only;
397 - insert new item into the list;
398 - if inserting is successful, initialize non-key fields of item by calling \p func functor
400 This can be useful if complete initialization of object of \p value_type is heavyweight and
401 it is preferable that the initialization should be completed only if inserting is successful.
403 template <typename Q, typename Func>
404 bool insert( Q const& key, Func func )
406 return insert_at( head(), key, func );
409 /// Inserts data of type \p value_type constructed from \p args
411 Returns \p true if inserting successful, \p false otherwise.
413 template <typename... Args>
414 bool emplace( Args&&... args )
416 return emplace_at( head(), std::forward<Args>(args)... );
419 /// Updates data by \p key
421 The operation performs inserting or replacing the element with lock-free manner.
423 If the \p key not found in the list, then the new item created from \p key
424 will be inserted iff \p bAllowInsert is \p true.
425 Otherwise, if \p key is found, the functor \p func is called with item found.
427 The functor \p Func signature is:
430 void operator()( bool bNew, value_type& item, Q const& val );
435 - \p bNew - \p true if the item has been inserted, \p false otherwise
436 - \p item - item of the list
437 - \p val - argument \p key passed into the \p %update() function
439 The functor may change non-key fields of the \p item;
440 during \p func call \p item is locked so it is safe to modify the item in
441 multi-threaded environment.
443 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
444 \p second is true if new item has been added or \p false if the item with \p key
447 template <typename Q, typename Func>
448 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
450 return update_at( head(), key, func, bAllowInsert );
453 template <typename Q, typename Func>
454 CDS_DEPRECATED("ensure() is deprecated, use update()")
455 std::pair<bool, bool> ensure( Q const& key, Func f )
457 return update( key, f, true );
461 /// Deletes \p key from the list
462 /** \anchor cds_nonintrusive_LazyList_hp_erase_val
463 Since the key of LazyList's item type \p T is not explicitly specified,
464 template parameter \p Q defines the key type searching in the list.
465 The list item comparator should be able to compare the type \p T of list item
468 Return \p true if key is found and deleted, \p false otherwise
470 template <typename Q>
471 bool erase( Q const& key )
473 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
476 /// Deletes the item from the list using \p pred predicate for searching
478 The function is an analog of \ref cds_nonintrusive_LazyList_hp_erase_val "erase(Q const&)"
479 but \p pred is used for key comparing.
480 \p Less functor has the interface like \p std::less.
481 \p pred must imply the same element order as the comparator used for building the list.
483 template <typename Q, typename Less>
484 bool erase_with( Q const& key, Less pred )
487 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
490 /// Deletes \p key from the list
491 /** \anchor cds_nonintrusive_LazyList_hp_erase_func
492 The function searches an item with key \p key, calls \p f functor with item found
493 and deletes the item. If \p key is not found, the functor is not called.
495 The functor \p Func interface:
498 void operator()(const value_type& val) { ... }
502 Since the key of LazyList's item type \p T is not explicitly specified,
503 template parameter \p Q defines the key type searching in the list.
504 The list item comparator should be able to compare the type \p T of list item
507 Return \p true if key is found and deleted, \p false otherwise
511 template <typename Q, typename Func>
512 bool erase( Q const& key, Func f )
514 return erase_at( head(), key, intrusive_key_comparator(), f );
517 /// Deletes the item from the list using \p pred predicate for searching
519 The function is an analog of \ref cds_nonintrusive_LazyList_hp_erase_func "erase(Q const&, Func)"
520 but \p pred is used for key comparing.
521 \p Less functor has the interface like \p std::less.
522 \p pred must imply the same element order as the comparator used for building the list.
524 template <typename Q, typename Less, typename Func>
525 bool erase_with( Q const& key, Less pred, Func f )
528 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
531 /// Extracts the item from the list with specified \p key
532 /** \anchor cds_nonintrusive_LazyList_hp_extract
533 The function searches an item with key equal to \p key,
534 unlinks it from the list, and returns it as \p guarded_ptr.
535 If \p key is not found the function returns an empty guarded pointer.
537 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
539 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
543 typedef cds::container::LazyList< cds::gc::HP, foo, my_traits > ord_list;
547 ord_list::guarded_ptr gp(theList.extract( 5 ));
552 // Destructor of gp releases internal HP guard and frees the item
556 template <typename Q>
557 guarded_ptr extract( Q const& key )
560 extract_at( head(), gp.guard(), key, intrusive_key_comparator() );
564 /// Extracts the item from the list with comparing functor \p pred
566 The function is an analog of \ref cds_nonintrusive_LazyList_hp_extract "extract(Q const&)"
567 but \p pred predicate is used for key comparing.
569 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
571 \p pred must imply the same element order as the comparator used for building the list.
573 template <typename Q, typename Less>
574 guarded_ptr extract_with( Q const& key, Less pred )
578 extract_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
582 /// Checks whether the list contains \p key
584 The function searches the item with key equal to \p key
585 and returns \p true if it is found, and \p false otherwise.
587 template <typename Q>
588 bool contains( Q const& key )
590 return find_at( head(), key, intrusive_key_comparator() );
593 template <typename Q>
594 CDS_DEPRECATED("deprecated, use contains()")
595 bool find( Q const& key )
597 return contains( key );
601 /// Checks whether the list contains \p key using \p pred predicate for searching
603 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
604 \p Less functor has the interface like \p std::less.
605 \p pred must imply the same element order as the comparator used for building the list.
607 template <typename Q, typename Less>
608 bool contains( Q const& key, Less pred )
611 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
614 template <typename Q, typename Less>
615 CDS_DEPRECATED("deprecated, use contains()")
616 bool find_with( Q const& key, Less pred )
618 return contains( key, pred );
621 /// Finds the key \p key and performs an action with it
622 /** \anchor cds_nonintrusive_LazyList_hp_find_func
623 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
624 The interface of \p Func functor is:
627 void operator()( value_type& item, Q& key );
630 where \p item is the item found, \p key is the <tt>find</tt> function argument.
632 The functor may change non-key fields of \p item. Note that the function is only guarantee
633 that \p item cannot be deleted during functor is executing.
634 The function does not serialize simultaneous access to the list \p item. If such access is
635 possible you must provide your own synchronization schema to exclude unsafe item modifications.
637 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
638 may modify both arguments.
640 The function returns \p true if \p key is found, \p false otherwise.
642 template <typename Q, typename Func>
643 bool find( Q& key, Func f )
645 return find_at( head(), key, intrusive_key_comparator(), f );
648 template <typename Q, typename Func>
649 bool find( Q const& key, Func f )
651 return find_at( head(), key, intrusive_key_comparator(), f );
655 /// Finds the key \p key using \p pred predicate for searching
657 The function is an analog of \ref cds_nonintrusive_LazyList_hp_find_func "find(Q&, Func)"
658 but \p pred is used for key comparing.
659 \p Less functor has the interface like \p std::less.
660 \p pred must imply the same element order as the comparator used for building the list.
662 template <typename Q, typename Less, typename Func>
663 bool find_with( Q& key, Less pred, Func f )
666 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
669 template <typename Q, typename Less, typename Func>
670 bool find_with( Q const& key, Less pred, Func f )
673 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
677 /// Finds the key \p key and return the item found
678 /** \anchor cds_nonintrusive_LazyList_hp_get
679 The function searches the item with key equal to \p key
680 and returns the item found as \p guarded_ptr.
681 If \p key is not found the function returns an empty guarded pointer.
683 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
687 typedef cds::container::LazyList< cds::gc::HP, foo, my_traits > ord_list;
691 ord_list::guarded_ptr gp( theList.get( 5 ));
696 // Destructor of guarded_ptr releases internal HP guard and frees the item
700 Note the compare functor specified for class \p Traits template parameter
701 should accept a parameter of type \p Q that can be not the same as \p value_type.
703 template <typename Q>
704 guarded_ptr get( Q const& key )
707 get_at( head(), gp.guard(), key, intrusive_key_comparator() );
711 /// Finds the key \p key and return the item found
713 The function is an analog of \ref cds_nonintrusive_LazyList_hp_get "get( Q const&)"
714 but \p pred is used for comparing the keys.
716 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
718 \p pred must imply the same element order as the comparator used for building the list.
720 template <typename Q, typename Less>
721 guarded_ptr get_with( Q const& key, Less pred )
725 get_at( head(), gp.guard(), key, typename maker::template less_wrapper<Less>::type() );
729 /// Checks whether the list is empty
732 return base_class::empty();
735 /// Returns list's item count
737 The value returned depends on \p Traits::item_counter type. For \p atomicity::empty_item_counter,
738 this function always returns 0.
740 @note Even if you use real item counter and it returns 0, this fact is not mean that the list
741 is empty. To check list emptyness use \ref empty() method.
745 return base_class::size();
756 bool insert_node_at( head_type& refHead, node_type * pNode )
758 assert( pNode != nullptr );
759 scoped_node_ptr p( pNode );
761 if ( base_class::insert_at( &refHead, *pNode )) {
769 template <typename Q>
770 bool insert_at( head_type& refHead, const Q& val )
772 return insert_node_at( refHead, alloc_node( val ));
775 template <typename... Args>
776 bool emplace_at( head_type& refHead, Args&&... args )
778 return insert_node_at( refHead, alloc_node( std::forward<Args>(args)... ));
781 template <typename Q, typename Func>
782 bool insert_at( head_type& refHead, const Q& key, Func f )
784 scoped_node_ptr pNode( alloc_node( key ));
786 if ( base_class::insert_at( &refHead, *pNode, [&f](node_type& node){ f( node_to_value(node) ); } )) {
793 template <typename Q, typename Compare, typename Func>
794 bool erase_at( head_type& refHead, const Q& key, Compare cmp, Func f )
796 return base_class::erase_at( &refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
799 template <typename Q, typename Compare>
800 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
802 return base_class::extract_at( &refHead, guard, key, cmp );
805 template <typename Q, typename Func>
806 std::pair<bool, bool> update_at( head_type& refHead, const Q& key, Func f, bool bAllowInsert )
808 scoped_node_ptr pNode( alloc_node( key ));
810 std::pair<bool, bool> ret = base_class::update_at( &refHead, *pNode,
811 [&f, &key](bool bNew, node_type& node, node_type&){f( bNew, node_to_value(node), key );},
813 if ( ret.first && ret.second )
819 template <typename Q, typename Compare>
820 bool find_at( head_type& refHead, Q const& key, Compare cmp )
822 return base_class::find_at( &refHead, key, cmp );
825 template <typename Q, typename Compare, typename Func>
826 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
828 return base_class::find_at( &refHead, val, cmp, [&f](node_type& node, Q& val){ f( node_to_value(node), val ); });
831 template <typename Q, typename Compare>
832 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, Q const& key, Compare cmp )
834 return base_class::get_at( &refHead, guard, key, cmp );
840 }} // namespace cds::container
842 #endif // #ifndef CDSLIB_CONTAINER_IMPL_LAZY_LIST_H