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_ITERABLE_KVLIST_H
32 #define CDSLIB_CONTAINER_IMPL_ITERABLE_KVLIST_H
35 #include <cds/container/details/guarded_ptr_cast.h>
37 namespace cds { namespace container {
39 /// Iterable ordered list for key-value pair
40 /** @ingroup cds_nonintrusive_list
41 \anchor cds_nonintrusive_IterableKVList_gc
43 This is key-value variation of non-intrusive \p IterableList.
44 Like standard container, this implementation split a value stored into two part -
45 constant key and alterable value.
47 Usually, ordered single-linked list is used as a building block for the hash table implementation.
48 Iterable list is suitable for almost append-only hash table because the list doesn't delete
49 its internal node when erasing a key but it is marked them as empty to be reused in the future.
50 However, plenty of empty nodes degrades performance.
52 The complexity of searching is <tt>O(N)</tt>.
55 - \p GC - garbage collector used
56 - \p Key - key type of an item stored in the list. It should be copy-constructible
57 - \p Value - value type stored in a list
58 - \p Traits - type traits, default is \p iterable_list::traits
60 It is possible to declare option-based list with \p cds::container::iterable_list::make_traits metafunction instead of \p Traits template
61 argument. For example, the following traits-based declaration of \p gc::HP iterable list
63 #include <cds/container/iterable_kvlist_hp.h>
64 // Declare comparator for the item
66 int operator ()( int i1, int i2 )
73 struct my_traits: public cds::container::iterable_list::traits
75 typedef my_compare compare;
78 // Declare traits-based list
79 typedef cds::container::IterableKVList< cds::gc::HP, int, int, my_traits > traits_based_list;
81 is equivalent for the following option-based list
83 #include <cds/container/iterable_kvlist_hp.h>
85 // my_compare is the same
87 // Declare option-based list
88 typedef cds::container::IterableKVList< cds::gc::HP, int, int,
89 typename cds::container::iterable_list::make_traits<
90 cds::container::opt::compare< my_compare > // item comparator option
96 There are different specializations of this template for each garbage collecting schema used.
97 You should include appropriate .h-file depending on GC you are using:
98 - for gc::HP: \code #include <cds/container/iterable_kvlist_hp.h> \endcode
99 - for gc::DHP: \code #include <cds/container/iterable_kvlist_dhp.h> \endcode
100 - for \ref cds_urcu_desc "RCU": \code #include <cds/container/iterable_kvlist_rcu.h> \endcode
106 #ifdef CDS_DOXYGEN_INVOKED
107 typename Traits = iterable_list::traits
112 class IterableKVList:
113 #ifdef CDS_DOXYGEN_INVOKED
114 protected container::IterableList< GC, std::pair<Key, Value>, Traits >
116 protected details::make_iterable_kvlist< GC, Key, Value, Traits >::type
120 typedef details::make_iterable_kvlist< GC, Key, Value, Traits > maker;
121 typedef typename maker::type base_class;
125 #ifdef CDS_DOXYGEN_INVOKED
126 typedef Key key_type ; ///< Key type
127 typedef Value mapped_type ; ///< Type of value stored in the list
128 typedef std::pair<key_type const, mapped_type> value_type ; ///< key/value pair stored in the list
130 typedef typename maker::key_type key_type;
131 typedef typename maker::mapped_type mapped_type;
132 typedef typename maker::value_type value_type;
135 typedef typename base_class::gc gc; ///< Garbage collector used
136 typedef typename base_class::back_off back_off; ///< Back-off strategy used
137 typedef typename maker::data_allocator_type allocator_type; ///< Allocator type used for allocate/deallocate data
138 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
139 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
140 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
141 typedef typename base_class::stat stat; ///< Internal statistics
143 static CDS_CONSTEXPR const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
146 typedef typename base_class::guarded_ptr guarded_ptr;
150 typedef typename base_class::head_type head_type;
151 typedef typename maker::cxx_data_allocator cxx_data_allocator;
153 template <typename Less>
154 using less_wrapper = typename maker::template less_wrapper< Less >;
156 template <bool IsConst>
157 using iterator_type = typename base_class::template iterator_type<IsConst>;
163 The forward iterator for iterable list has some features:
164 - it has no post-increment operator
165 - to protect the value, the iterator contains a GC-specific guard.
166 For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
167 may be thrown if the limit of guard count per thread is exceeded.
168 - The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
169 - Iterator is thread-safe: even if an element the iterator points to is removed, the iterator stays valid because
170 it contains the guard keeping the value from to be recycled.
172 The iterator interface:
176 // Default constructor
180 iterator( iterator const& src );
182 // Dereference operator
183 value_type * operator ->() const;
185 // Dereference operator
186 value_type& operator *() const;
188 // Preincrement operator
189 iterator& operator ++();
191 // Assignment operator
192 iterator& operator = (iterator const& src);
194 // Equality operators
195 bool operator ==(iterator const& i ) const;
196 bool operator !=(iterator const& i ) const;
200 @note For two iterators pointed to the same element the value can be different;
204 assert( &(*it1) == &(*it2) );
206 can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread.
207 The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing.
208 Other iterator can observe modified value of the element.
210 using typename base_class::iterator;
211 using typename base_class::const_iterator;
212 using base_class::begin;
213 using base_class::end;
214 using base_class::cbegin;
215 using base_class::cend;
218 /// Default constructor
220 Initializes empty list
226 template <typename Stat, typename = std::enable_if<std::is_same<stat, iterable_list::wrapped_stat<Stat>>::value >>
227 explicit IterableKVList( Stat& st )
239 /// Inserts new node with key and default value
241 The function creates a node with \p key and default value, and then inserts the node created into the list.
244 - The \p key_type should be constructible from value of type \p K. In trivial case, \p K is equal to \p key_type.
245 - The \p mapped_type should be default-constructible.
247 Returns \p true if inserting successful, \p false otherwise.
249 @note The function is supported only if \ref mapped_type is default constructible
251 template <typename K>
252 bool insert( K const& key )
254 return base_class::emplace( key, mapped_type());
257 /// Inserts new node with a key and a value
259 The function creates a node with \p key and value \p val, and then inserts the node created into the list.
262 - The \p key_type should be constructible from \p key of type \p K.
263 - The \p mapped_type should be constructible from \p val of type \p V.
265 Returns \p true if inserting successful, \p false otherwise.
267 template <typename K, typename V>
268 bool insert( K const& key, V const& val )
270 return base_class::emplace( key, val );
273 /// Inserts new node and initialize it by a functor
275 This function inserts new node with key \p key and if inserting is successful then it calls
276 \p func functor with signature
279 void operator()( value_type& item );
283 The argument \p item of user-defined functor \p func is the reference
284 to the item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
285 User-defined functor \p func should guarantee that during changing item's value no any other changes
286 could be made on this list's item by concurrent threads.
287 The user-defined functor is called only if inserting is successful.
289 The \p key_type should be constructible from value of type \p K.
291 The function allows to split creating of new item into two part:
292 - create a new item from \p key;
293 - insert the new item into the list;
294 - if inserting is successful, initialize the value of item by calling \p func functor
296 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
297 it is preferable that the initialization should be completed only if inserting is successful.
299 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
301 @note The function is supported only if \ref mapped_type is default constructible
303 template <typename K, typename Func>
304 bool insert_with( K const& key, Func func )
306 return base_class::insert( value_type( key, mapped_type()), func );
309 /// Updates data by \p key
311 The operation performs inserting or replacing the element with lock-free manner.
313 If the \p key not found in the list, then the new item created from \p key
314 will be inserted iff \p bAllowInsert is \p true.
315 (note that in this case the \ref key_type should be constructible from type \p K).
316 Otherwise, if \p key is found, the functor \p func is called with item found.
318 The functor \p func is called after inserting or replacing, it signature is:
320 void func( value_type& val, value_type* old );
323 - \p val - a new data constructed from \p key
324 - \p old - old value that will be retired. If new item has been inserted then \p old is \p nullptr.
326 The functor may change non-key fields of \p val; however, \p func must guarantee
327 that during changing no any other modifications could be made on this item by concurrent threads.
329 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
330 \p second is true if new item has been added or \p false if the item with such \p key
333 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
335 @note The function is supported only if \ref mapped_type is default constructible
337 template <typename K, typename Func>
338 std::pair<bool, bool> update( K const& key, Func f, bool bAllowInsert = true )
340 return base_class::update( value_type( key, mapped_type()), f, bAllowInsert );
345 The operation performs inserting or updating data with lock-free manner.
347 If the item \p key is not found in the list, then \p key is inserted
348 iff \p bInsert is \p true.
349 Otherwise, the current element is changed to <tt> value_type( key, val )</tt>,
350 the old element will be retired later.
352 Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
353 \p second is \p true if \p key has been added or \p false if the item with that key
356 template <typename Q, typename V >
357 std::pair<bool, bool> upsert( Q&& key, V&& val, bool bInsert = true )
359 return base_class::upsert( value_type( std::forward<Q>( key ), std::forward<V>( val )), bInsert );
362 /// Inserts a new node using move semantics
364 \p key_type field of new item is constructed from \p key argument,
365 \p mapped_type field is done from \p args.
367 Returns \p true if inserting successful, \p false otherwise.
369 template <typename K, typename... Args>
370 bool emplace( K&& key, Args&&... args )
372 return base_class::emplace( std::forward<K>( key ), std::forward<Args>( args )... );
375 /// Deletes \p key from the list
378 Returns \p true if \p key is found and has been deleted, \p false otherwise
380 template <typename K>
381 bool erase( K const& key )
383 return base_class::erase( key );
386 /// Deletes the item from the list using \p pred predicate for searching
388 The function is an analog of \p erase(K const&) but \p pred is used for key comparing.
389 \p Less functor has the interface like \p std::less.
390 \p pred must imply the same element order as the comparator used for building the list.
392 template <typename K, typename Less>
393 bool erase_with( K const& key, Less pred )
396 return base_class::erase_with( key, less_wrapper<Less>() );
399 /// Deletes \p key from the list
401 The function searches an item with key \p key, calls \p f functor
402 and deletes the item. If \p key is not found, the functor is not called.
404 The functor \p Func interface:
407 void operator()(value_type& val) { ... }
411 Return \p true if key is found and deleted, \p false otherwise
413 template <typename K, typename Func>
414 bool erase( K const& key, Func f )
416 return base_class::erase( key, f );
419 /// Deletes the item from the list using \p pred predicate for searching
421 The function is an analog of \p erase(K const&, Func) but \p pred is used for key comparing.
422 \p Less functor has the interface like \p std::less.
423 \p pred must imply the same element order as the comparator used for building the list.
425 template <typename K, typename Less, typename Func>
426 bool erase_with( K const& key, Less pred, Func f )
429 return base_class::erase_with( key, less_wrapper<Less>(), f );
432 /// Extracts the item from the list with specified \p key
434 The function searches an item with key equal to \p key,
435 unlinks it from the list, and returns it as \p guarded_ptr.
436 If \p key is not found the function returns an empty guarded pointer.
438 Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
440 The \p disposer specified in \p Traits class template parameter is called automatically
441 by garbage collector \p GC specified in class' template parameters when returned \p guarded_ptr object
442 will be destroyed or released.
443 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
447 typedef cds::container::IterableKVList< cds::gc::HP, int, foo, my_traits > ord_list;
451 ord_list::guarded_ptr gp(theList.extract( 5 ));
456 // Destructor of gp releases internal HP guard
460 template <typename K>
461 guarded_ptr extract( K const& key )
463 return base_class::extract( key );
466 /// Extracts the item from the list with comparing functor \p pred
468 The function is an analog of \p extract(K const&) but \p pred predicate is used for key comparing.
470 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
472 \p pred must imply the same element order as the comparator used for building the list.
474 template <typename K, typename Less>
475 guarded_ptr extract_with( K const& key, Less pred )
478 return base_class::extract_with( key, less_wrapper<Less>() );
481 /// Checks whether the list contains \p key
483 The function searches the item with key equal to \p key
484 and returns \p true if it is found, and \p false otherwise.
486 template <typename Q>
487 bool contains( Q const& key ) const
489 return base_class::contains( key );
492 /// Checks whether the map contains \p key using \p pred predicate for searching
494 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
495 \p Less functor has the interface like \p std::less.
496 \p Less must imply the same element order as the comparator used for building the list.
498 template <typename Q, typename Less>
499 bool contains( Q const& key, Less pred ) const
502 return base_class::contains( key, less_wrapper<Less>() );
505 /// Finds the key \p key and performs an action with it
507 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
508 The interface of \p Func functor is:
511 void operator()( value_type& item );
514 where \p item is the item found.
516 The functor may change <tt>item.second</tt> that is reference to value of node.
517 Note that the function is only guarantee that \p item cannot be deleted during functor is executing.
518 The function does not serialize simultaneous access to the list \p item. If such access is
519 possible you must provide your own synchronization schema to exclude unsafe item modifications.
521 The function returns \p true if \p key is found, \p false otherwise.
523 template <typename Q, typename Func>
524 bool find( Q const& key, Func f ) const
526 return base_class::find( key, [&f]( value_type& v, Q const& ) { f( v ); } );
529 /// Finds \p key in the list and returns iterator pointed to the item found
531 If \p key is not found the function returns \p end().
533 template <typename Q>
534 iterator find( Q const& key ) const
536 return base_class::find( key );
539 /// Finds the key \p val using \p pred predicate for searching
541 The function is an analog of \p find(Q&, Func) but \p pred is used for key comparing.
542 \p Less functor has the interface like \p std::less.
543 \p pred must imply the same element order as the comparator used for building the list.
545 template <typename Q, typename Less, typename Func>
546 bool find_with( Q const& key, Less pred, Func f ) const
549 return base_class::find_with( key, less_wrapper<Less>(), [&f]( value_type& v, Q const& ) { f( v ); } );
552 /// Finds \p key in the list using \p pred predicate for searching and returns iterator pointed to the item found
554 The function is an analog of \p find(Q&) but \p pred is used for key comparing.
555 \p Less functor has the interface like \p std::less.
556 \p pred must imply the same element order as the comparator used for building the list.
558 If \p key is not found the function returns \p end().
560 template <typename Q, typename Less>
561 iterator find_with( Q const& key, Less pred ) const
564 return base_class::find_with( key, less_wrapper<Less>());
567 /// Finds the \p key and return the item found
569 The function searches the item with key equal to \p key
570 and returns it as \p guarded_ptr.
571 If \p key is not found the function returns an empty guarded pointer.
573 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
577 typedef cds::container::IterableKVList< cds::gc::HP, int, foo, my_traits > ord_list;
581 ord_list::guarded_ptr gp(theList.get( 5 ));
586 // Destructor of guarded_ptr releases internal HP guard
590 Note the compare functor specified for class \p Traits template parameter
591 should accept a parameter of type \p K that can be not the same as \p key_type.
593 template <typename K>
594 guarded_ptr get( K const& key ) const
596 return base_class::get( key );
599 /// Finds the \p key and return the item found
601 The function is an analog of \p get( guarded_ptr& ptr, K const&)
602 but \p pred is used for comparing the keys.
604 \p Less functor has the semantics like \p std::less but should take arguments of type \ref key_type and \p K
606 \p pred must imply the same element order as the comparator used for building the list.
608 template <typename K, typename Less>
609 guarded_ptr get_with( K const& key, Less pred ) const
612 return base_class::get_with( key, less_wrapper<Less>() );
615 /// Checks if the list is empty
617 Emptiness is checked by item counting: if item count is zero then the set is empty.
618 Thus, if you need to use \p %empty() you should provide appropriate (non-empty) \p iterable_list::traits::item_counter
623 return base_class::empty();
626 /// Returns list's item count
628 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
629 this function always returns 0.
633 return base_class::size();
642 /// Returns const reference to internal statistics
643 stat const& statistics() const
645 return base_class::statistics();
650 // Split-list support
652 template <typename K>
653 bool insert_at( head_type& refHead, const K& key )
655 return base_class::insert_at( refHead, value_type( key, mapped_type() ));
658 template <typename K, typename V>
659 bool insert_at( head_type& refHead, const K& key, const V& val )
661 return base_class::insert_at( refHead, value_type( key, val ));
664 template <typename K, typename Func>
665 bool insert_with_at( head_type& refHead, const K& key, Func f )
667 return base_class::insert_at( refHead, value_type( key, mapped_type()), f );
670 template <typename K, typename... Args>
671 bool emplace_at( head_type& refHead, K&& key, Args&&... args )
673 return base_class::emplace_at( refHead, std::forward<K>(key), std::forward<Args>(args)... );
676 template <typename K, typename Func>
677 std::pair<bool, bool> update_at( head_type& refHead, const K& key, Func f, bool bAllowInsert )
679 return base_class::update_at( refHead, value_type( key, mapped_type()), f, bAllowInsert );
682 template <typename K, typename Compare>
683 bool erase_at( head_type& refHead, K const& key, Compare cmp )
685 return base_class::erase_at( refHead, key, cmp );
688 template <typename K, typename Compare, typename Func>
689 bool erase_at( head_type& refHead, K const& key, Compare cmp, Func f )
691 return base_class::erase_at( refHead, key, cmp, f );
693 template <typename K, typename Compare>
694 bool extract_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
696 return base_class::extract_at( refHead, guard, key, cmp );
699 template <typename K, typename Compare>
700 bool find_at( head_type& refHead, K const& key, Compare cmp )
702 return base_class::find_at( refHead, key, cmp );
705 template <typename K, typename Compare, typename Func>
706 bool find_at( head_type& refHead, K& key, Compare cmp, Func f )
708 return base_class::find_at( refHead, key, cmp, f );
711 template <typename K, typename Compare>
712 bool get_at( head_type& refHead, typename guarded_ptr::native_guard& guard, K const& key, Compare cmp )
714 return base_class::get_at( refHead, guard, key, cmp );
720 }} // namespace cds::container
722 #endif // #ifndef CDSLIB_CONTAINER_IMPL_ITERABLE_KVLIST_H