3 #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H
4 #define __CDS_CONTAINER_MICHAEL_LIST_RCU_H
7 #include <cds/container/details/michael_list_base.h>
8 #include <cds/intrusive/michael_list_rcu.h>
9 #include <cds/container/details/make_michael_list.h>
10 #include <cds/details/binary_functor_wrapper.h>
12 namespace cds { namespace container {
14 /// Michael's ordered list (template specialization for \ref cds_urcu_desc "RCU")
15 /** @ingroup cds_nonintrusive_list
16 \anchor cds_nonintrusive_MichaelList_rcu
18 Usually, ordered single-linked list is used as a building block for the hash table implementation.
19 The complexity of searching is <tt>O(N)</tt>.
22 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
24 This class is non-intrusive version of \ref cds_intrusive_MichaelList_rcu "cds::intrusive::MichaelList" RCU specialization.
27 - \p RCU - one of \ref cds_urcu_gc "RCU type"
28 - \p T - type stored in the list. The type must be default- and copy-constructible.
29 - \p Traits - type traits, default is michael_list::traits
31 The implementation does not divide type \p T into key and value part and
32 may be used as a main building block for hash set containers.
33 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
34 or <tt>Traits::less</tt> predicate.
36 \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" is a key-value version of Michael's
37 non-intrusive list that is closer to the C++ std library approach.
39 @note Before including <tt><cds/container/michael_list_rcu.h></tt> you should include appropriate RCU header file,
40 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
42 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
43 argument. For example, the following traits-based declaration of Michael's list
46 #include <cds/urcu/general_buffered.h>
47 #include <cds/container/michael_list_rcu.h>
48 // Declare comparator for the item
50 int operator ()( int i1, int i2 )
57 struct my_traits: public cds::container::michael_list::traits
59 typedef my_compare compare;
62 // Declare traits-based list
63 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, my_traits > traits_based_list;
66 is equivalent for the following option-based list
68 #include <cds/urcu/general_buffered.h>
69 #include <cds/container/michael_list_rcu.h>
71 // my_compare is the same
73 // Declare option-based list
74 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int,
75 typename cds::container::michael_list::make_traits<
76 cds::container::opt::compare< my_compare > // item comparator option
81 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
82 - opt::compare - key comparison functor. No default functor is provided.
83 If the option is not specified, the opt::less is used.
84 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
85 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
86 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
87 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
88 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
89 or opt::v::sequential_consistent (sequentially consisnent memory model).
90 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
95 #ifdef CDS_DOXYGEN_INVOKED
96 typename Traits = michael_list::traits
101 class MichaelList< cds::urcu::gc<RCU>, T, Traits > :
102 #ifdef CDS_DOXYGEN_INVOKED
103 protected intrusive::MichaelList< cds::urcu::gc<RCU>, T, Traits >
105 protected details::make_michael_list< cds::urcu::gc<RCU>, T, Traits >::type
109 typedef details::make_michael_list< cds::urcu::gc<RCU>, T, Traits > maker;
110 typedef typename maker::type base_class;
114 typedef cds::urcu::gc<RCU> gc; ///< RCU
115 typedef T value_type; ///< Type of value stored in the list
116 typedef Traits traits; ///< List traits
118 typedef typename base_class::back_off back_off; ///< Back-off strategy used
119 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
120 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
121 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
122 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
123 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
125 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
126 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions require external locking
130 typedef typename base_class::value_type node_type;
131 typedef typename maker::cxx_allocator cxx_allocator;
132 typedef typename maker::node_deallocator node_deallocator;
133 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
135 typedef typename base_class::atomic_node_ptr head_type;
139 typedef cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer > exempt_ptr; ///< pointer to extracted node
143 static value_type& node_to_value( node_type& n )
147 static value_type const& node_to_value( node_type const& n )
155 template <typename Q>
156 static node_type * alloc_node( Q const& v )
158 return cxx_allocator().New( v );
161 template <typename... Args>
162 static node_type * alloc_node( Args&&... args )
164 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
167 static void free_node( node_type * pNode )
169 cxx_allocator().Delete( pNode );
172 struct node_disposer {
173 void operator()( node_type * pNode )
178 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
182 return base_class::m_pHead;
185 head_type& head() const
187 return const_cast<head_type&>( base_class::m_pHead );
193 template <bool IsConst>
194 class iterator_type: protected base_class::template iterator_type<IsConst>
196 typedef typename base_class::template iterator_type<IsConst> iterator_base;
198 iterator_type( head_type const& pNode )
199 : iterator_base( pNode )
202 friend class MichaelList;
205 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
206 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
211 iterator_type( iterator_type const& src )
212 : iterator_base( src )
215 value_ptr operator ->() const
217 typename iterator_base::value_ptr p = iterator_base::operator ->();
218 return p ? &(p->m_Value) : nullptr;
221 value_ref operator *() const
223 return (iterator_base::operator *()).m_Value;
227 iterator_type& operator ++()
229 iterator_base::operator ++();
234 bool operator ==(iterator_type<C> const& i ) const
236 return iterator_base::operator ==(i);
239 bool operator !=(iterator_type<C> const& i ) const
241 return iterator_base::operator !=(i);
248 typedef iterator_type<false> iterator;
250 /// Const forward iterator
251 typedef iterator_type<true> const_iterator;
253 /// Returns a forward iterator addressing the first element in a list
255 For empty list \code begin() == end() \endcode
259 return iterator( head() );
262 /// Returns an iterator that addresses the location succeeding the last element in a list
264 Do not use the value returned by <tt>end</tt> function to access any item.
265 Internally, <tt>end</tt> returning value equals to \p nullptr.
267 The returned value can be used only to control reaching the end of the list.
268 For empty list \code begin() == end() \endcode
275 /// Returns a forward const iterator addressing the first element in a list
277 const_iterator begin() const
279 return const_iterator( head() );
281 const_iterator cbegin()
283 return const_iterator( head() );
287 /// Returns an const iterator that addresses the location succeeding the last element in a list
289 const_iterator end() const
291 return const_iterator();
293 const_iterator cend()
295 return const_iterator();
300 /// Default constructor
302 Initialize empty list
318 The function creates a node with copy of \p val value
319 and then inserts the node created into the list.
321 The type \p Q should contain as minimum the complete key of the node.
322 The object of \ref value_type should be constructible from \p val of type \p Q.
323 In trivial case, \p Q is equal to \ref value_type.
325 The function makes RCU lock internally.
327 Returns \p true if inserting successful, \p false otherwise.
329 template <typename Q>
330 bool insert( Q const& val )
332 return insert_at( head(), val );
337 This function inserts new node with default-constructed value and then it calls
338 \p func functor with signature
339 \code void func( value_type& itemValue ) ;\endcode
341 The argument \p itemValue of user-defined functor \p func is the reference
342 to the list's item inserted. User-defined functor \p func should guarantee that during changing
343 item's value no any other changes could be made on this list's item by concurrent threads.
344 The user-defined functor can be passed by reference using \p std::ref
345 and it is called only if the inserting is success.
347 The type \p Q should contain the complete key of the node.
348 The object of \ref value_type should be constructible from \p key of type \p Q.
350 The function allows to split creating of new item into two part:
351 - create item from \p key with initializing key-fields only;
352 - insert new item into the list;
353 - if inserting is successful, initialize non-key fields of item by calling \p f functor
355 This can be useful if complete initialization of object of \p value_type is heavyweight and
356 it is preferable that the initialization should be completed only if inserting is successful.
358 The function makes RCU lock internally.
360 template <typename Q, typename Func>
361 bool insert( Q const& key, Func func )
363 return insert_at( head(), key, func );
366 /// Ensures that the \p key exists in the list
368 The operation performs inserting or changing data with lock-free manner.
370 If the \p key not found in the list, then the new item created from \p key
371 is inserted into the list. Otherwise, the functor \p func is called with the item found.
372 The functor \p Func should be a function with signature:
374 void func( bool bNew, value_type& item, const Q& val );
379 void operator()( bool bNew, value_type& item, const Q& val );
384 - \p bNew - \p true if the item has been inserted, \p false otherwise
385 - \p item - item of the list
386 - \p val - argument \p key passed into the \p ensure function
388 The functor may change non-key fields of the \p item; however, \p func must guarantee
389 that during changing no any other modifications could be made on this item by concurrent threads.
391 The function makes RCU lock internally.
393 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
394 \p second is true if new item has been added or \p false if the item with \p key
395 already is in the list.
397 template <typename Q, typename Func>
398 std::pair<bool, bool> ensure( Q const& key, Func f )
400 return ensure_at( head(), key, f );
403 /// Inserts data of type \ref value_type constructed from \p args
405 Returns \p true if inserting successful, \p false otherwise.
407 The function makes RCU lock internally.
409 template <typename... Args>
410 bool emplace( Args&&... args )
412 return emplace_at( head(), std::forward<Args>(args)... );
415 /// Deletes \p key from the list
416 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
417 Since the key of MichaelList's item type \p value_type is not explicitly specified,
418 template parameter \p Q defines the key type searching in the list.
419 The list item comparator should be able to compare values of the type \p value_type
420 and \p Q in any order.
422 RCU \p synchronize method can be called. RCU should not be locked.
424 Return \p true if key is found and deleted, \p false otherwise
426 template <typename Q>
427 bool erase( Q const& key )
429 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
432 /// Deletes the item from the list using \p pred predicate for searching
434 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
435 but \p pred is used for key comparing.
436 \p Less functor has the interface like \p std::less.
437 \p pred must imply the same element order as the comparator used for building the list.
439 template <typename Q, typename Less>
440 bool erase_with( Q const& key, Less pred )
442 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
445 /// Deletes \p key from the list
446 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
447 The function searches an item with key \p key, calls \p f functor with item found
448 and deletes it. If \p key is not found, the functor is not called.
450 The functor \p Func interface:
453 void operator()(const value_type& val) { ... }
457 Since the key of MichaelList's item type \p value_type is not explicitly specified,
458 template parameter \p Q defines the key type searching in the list.
459 The list item comparator should be able to compare the values of type \p value_type
460 and \p Q in any order.
462 RCU \p synchronize method can be called. RCU should not be locked.
464 Return \p true if key is found and deleted, \p false otherwise
466 template <typename Q, typename Func>
467 bool erase( Q const& key, Func f )
469 return erase_at( head(), key, intrusive_key_comparator(), f );
472 /// Deletes the item from the list using \p pred predicate for searching
474 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
475 but \p pred is used for key comparing.
476 \p Less functor has the interface like \p std::less.
477 \p pred must imply the same element order as the comparator used for building the list.
479 template <typename Q, typename Less, typename Func>
480 bool erase_with( Q const& key, Less pred, Func f )
482 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
485 /// Extracts an item from the list
487 @anchor cds_nonintrusive_MichaelList_rcu_extract
488 The function searches an item with key equal to \p key in the list,
489 unlinks it from the list, and returns pointer to an item found in \p dest argument.
490 If the item with the key equal to \p key is not found the function returns \p false.
492 @note The function does NOT call RCU read-side lock or synchronization,
493 and does NOT dispose the item found. It just excludes the item from the list
494 and returns a pointer to item found.
495 You should lock RCU before calling this function.
498 #include <cds/urcu/general_buffered.h>
499 #include <cds/container/michael_list_rcu.h>
501 typedef cds::urcu::gc< general_buffered<> > rcu;
502 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
504 rcu_michael_list theList;
507 rcu_michael_list::exempt_ptr p;
509 // first, we should lock RCU
512 // Now, you can apply extract function
513 // Note that you must not delete the item found inside the RCU lock
514 if ( theList.extract( p, 10 )) {
515 // do something with p
519 // Outside RCU lock section we may safely release extracted pointer.
520 // release() passes the pointer to RCU reclamation cycle.
524 template <typename Q>
525 bool extract( exempt_ptr& dest, Q const& key )
527 dest = extract_at( head(), key, intrusive_key_comparator() );
528 return !dest.empty();
531 /// Extracts an item from the list using \p pred predicate for searching
533 This function is the analog for \ref cds_nonintrusive_MichaelList_rcu_extract "extract(exempt_ptr&, Q const&)".
535 The \p pred is a predicate used for key comparing.
536 \p Less has the interface like \p std::less.
537 \p pred must imply the same element order as \ref key_comparator.
539 template <typename Q, typename Less>
540 bool extract_with( exempt_ptr& dest, Q const& key, Less pred )
542 dest = extract_at( head(), key, typename maker::template less_wrapper<Less>::type() );
543 return !dest.empty();
546 /// Finds the key \p key
547 /** \anchor cds_nonintrusive_MichaelList_rcu_find_val
548 The function searches the item with key equal to \p key
549 and returns \p true if it is found, and \p false otherwise.
551 The function makes RCU lock internally.
553 template <typename Q>
554 bool find( Q const& key ) const
556 return find_at( head(), key, intrusive_key_comparator() );
559 /// Finds the key \p val using \p pred predicate for searching
561 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_val "find(Q const&)"
562 but \p pred is used for key comparing.
563 \p Less functor has the interface like \p std::less.
564 \p pred must imply the same element order as the comparator used for building the list.
566 template <typename Q, typename Less>
567 bool find_with( Q const& key, Less pred ) const
569 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
572 /// Finds the key \p key and performs an action with it
573 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
574 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
575 The interface of \p Func functor is:
578 void operator()( value_type& item, Q& key );
581 where \p item is the item found, \p key is the \p %find() function argument.
583 The functor may change non-key fields of \p item. Note that the function is only guarantee
584 that \p item cannot be deleted during functor is executing.
585 The function does not serialize simultaneous access to the list \p item. If such access is
586 possible you must provide your own synchronization schema to exclude unsafe item modifications.
588 The function makes RCU lock internally.
590 The function returns \p true if \p val is found, \p false otherwise.
592 template <typename Q, typename Func>
593 bool find( Q& key, Func f ) const
595 return find_at( head(), key, intrusive_key_comparator(), f );
598 /// Finds the key \p key using \p pred predicate for searching
600 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
601 but \p pred is used for key comparing.
602 \p Less functor has the interface like \p std::less.
603 \p pred must imply the same element order as the comparator used for building the list.
605 template <typename Q, typename Less, typename Func>
606 bool find_with( Q& key, Less pred, Func f ) const
608 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
611 /// Finds the key \p key and return the item found
612 /** \anchor cds_nonintrusive_MichaelList_rcu_get
613 The function searches the item with key equal to \p key and returns the pointer to item found.
614 If \p key is not found it returns \p nullptr.
616 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
618 RCU should be locked before call of this function.
619 Returned item is valid only while RCU is locked:
621 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
626 ord_list::rcu_lock lock;
628 foo * pVal = theList.get( 5 );
633 // Unlock RCU by rcu_lock destructor
634 // pVal can be freed at any time after RCU has been unlocked
638 template <typename Q>
639 value_type * get( Q const& key ) const
641 return get_at( head(), key, intrusive_key_comparator());
644 /// Finds \p key and return the item found
646 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
647 but \p pred is used for comparing the keys.
649 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
651 \p pred must imply the same element order as the comparator used for building the list.
653 template <typename Q, typename Less>
654 value_type * get_with( Q const& key, Less pred ) const
656 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
659 /// Checks if the list is empty
662 return base_class::empty();
665 /// Returns list's item count
667 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
668 this function always returns 0.
670 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
671 is empty. To check list emptyness use \p empty() method.
675 return base_class::size();
686 bool insert_node_at( head_type& refHead, node_type * pNode )
689 scoped_node_ptr p(pNode);
690 if ( base_class::insert_at( refHead, *pNode )) {
698 template <typename Q>
699 bool insert_at( head_type& refHead, Q const& val )
701 return insert_node_at( refHead, alloc_node( val ));
704 template <typename Q, typename Func>
705 bool insert_at( head_type& refHead, Q const& key, Func f )
707 scoped_node_ptr pNode( alloc_node( key ));
709 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
716 template <typename... Args>
717 bool emplace_at( head_type& refHead, Args&&... args )
719 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
722 template <typename Q, typename Compare, typename Func>
723 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
725 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
728 template <typename Q, typename Func>
729 std::pair<bool, bool> ensure_at( head_type& refHead, Q const& key, Func f )
731 scoped_node_ptr pNode( alloc_node( key ));
733 std::pair<bool, bool> ret = base_class::ensure_at( refHead, *pNode,
734 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key ); });
735 if ( ret.first && ret.second )
741 template <typename Q, typename Compare>
742 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
744 return base_class::extract_at( refHead, key, cmp );
747 template <typename Q, typename Compare>
748 bool find_at( head_type& refHead, Q const& key, Compare cmp ) const
750 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
753 template <typename Q, typename Compare, typename Func>
754 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f ) const
756 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
759 template <typename Q, typename Compare>
760 value_type * get_at( head_type& refHead, Q const& val, Compare cmp ) const
762 node_type * pNode = base_class::get_at( refHead, val, cmp );
763 return pNode ? &pNode->m_Value : nullptr;
769 }} // namespace cds::container
771 #endif // #ifndef __CDS_CONTAINER_MICHAEL_LIST_RCU_H