3 #ifndef __CDS_CONTAINER_SPLIT_LIST_MAP_H
4 #define __CDS_CONTAINER_SPLIT_LIST_MAP_H
6 #include <cds/container/split_list_set.h>
7 #include <cds/details/binary_functor_wrapper.h>
9 namespace cds { namespace container {
11 /// Split-ordered list map
12 /** @ingroup cds_nonintrusive_map
13 \anchor cds_nonintrusive_SplitListMap_hp
15 Hash table implementation based on split-ordered list algorithm discovered by Ori Shalev and Nir Shavit, see
16 - [2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"
17 - [2008] Nir Shavit "The Art of Multiprocessor Programming"
19 See intrusive::SplitListSet for a brief description of the split-list algorithm.
22 - \p GC - Garbage collector used
23 - \p Key - key type of an item stored in the map. It should be copy-constructible
24 - \p Value - value type stored in the map
25 - \p Traits - map traits, default is \p split_list::traits. Instead of declaring \p %split_list::traits -based
26 struct you may apply option-based notation with \p split_list::make_traits metafunction.
28 There are the specializations:
29 - for \ref cds_urcu_desc "RCU" - declared in <tt>cd/container/split_list_map_rcu.h</tt>,
30 see \ref cds_nonintrusive_SplitListMap_rcu "SplitListMap<RCU>".
31 - for \ref cds::gc::nogc declared in <tt>cds/container/split_list_map_nogc.h</tt>,
32 see \ref cds_nonintrusive_SplitListMap_nogc "SplitListMap<gc::nogc>".
36 You should decide what garbage collector you want, and what ordered list you want to use. Split-ordered list
37 is original data structure based on an ordered list. Suppose, you want construct split-list map based on \p gc::HP GC
38 and \p MichaelList as ordered list implementation. Your map should map \p int key to \p std::string value.
39 So, you beginning your program with following include:
41 #include <cds/container/michael_list_hp.h>
42 #include <cds/container/split_list_map.h>
44 namespace cc = cds::container;
46 The inclusion order is important: first, include file for ordered-list implementation (for this example, <tt>cds/container/michael_list_hp.h</tt>),
47 then the header for split-list map <tt>cds/container/split_list_map.h</tt>.
49 Now, you should declare traits for split-list map. The main parts of traits are a hash functor and a comparing functor for the ordered list.
50 We use <tt>std::hash<int></tt> as hash functor and <tt>std::less<int></tt> predicate as comparing functor.
52 The second attention: instead of using \p %MichaelList in \p %SplitListMap traits we use a tag \p cds::contaner::michael_list_tag for the Michael's list.
53 The split-list requires significant support from underlying ordered list class and it is not good idea to dive you
54 into deep implementation details of split-list and ordered list interrelations. The tag paradigm simplifies split-list interface.
57 // SplitListMap traits
58 struct foo_set_traits: public cc::split_list::traits
60 typedef cc::michael_list_tag ordered_list ; // what type of ordered list we want to use
61 typedef std::hash<int> hash ; // hash functor for the key stored in split-list map
63 // Type traits for our MichaelList class
64 struct ordered_list_traits: public cc::michael_list::traits
66 typedef std::less<int> less ; // use our std::less predicate as comparator to order list nodes
71 Now you are ready to declare our map class based on \p %SplitListMap:
73 typedef cc::SplitListMap< cds::gc::DHP, int, std::string, foo_set_traits > int_string_map;
76 You may use the modern option-based declaration instead of classic type-traits-based one:
78 typedef cc:SplitListMap<
79 cs::gc::DHP // GC used
81 ,std::string // value type
82 ,cc::split_list::make_traits< // metafunction to build split-list traits
83 cc::split_list::ordered_list<cc::michael_list_tag> // tag for underlying ordered list implementation
84 ,cc::opt::hash< std::hash<int> > // hash functor
85 ,cc::split_list::ordered_list_traits< // ordered list traits desired
86 cc::michael_list::make_traits< // metafunction to build lazy list traits
87 cc::opt::less< std::less<int> > // less-based compare functor
93 In case of option-based declaration with \p split_list::make_traits metafunction the struct \p foo_set_traits is not required.
95 Now, the map of type \p int_string_map is ready to use in your program.
97 Note that in this example we show only mandatory \p traits parts, optional ones is the default and they are inherited
98 from \p container::split_list::traits. There are many other options for deep tuning of the split-list and
99 ordered-list containers.
105 #ifdef CDS_DOXYGEN_INVOKED
106 class Traits = split_list::traits
112 protected container::SplitListSet<
114 std::pair<Key const, Value>,
115 split_list::details::wrap_map_traits<Key, Value, Traits>
119 typedef container::SplitListSet<
121 std::pair<Key const, Value>,
122 split_list::details::wrap_map_traits<Key, Value, Traits>
127 typedef GC gc; ///< Garbage collector
128 typedef Key key_type; ///< key type
129 typedef Value mapped_type; ///< type of value to be stored in the map
130 typedef Traits options; ///< Map traits
132 typedef std::pair<key_type const, mapped_type> value_type ; ///< key-value pair type
133 typedef typename base_class::ordered_list ordered_list; ///< Underlying ordered list class
134 typedef typename base_class::key_comparator key_comparator; ///< key compare functor
136 typedef typename base_class::hash hash; ///< Hash functor for \ref key_type
137 typedef typename base_class::item_counter item_counter; ///< Item counter type
138 typedef typename base_class::stat stat; ///< Internal statistics
142 typedef typename base_class::maker::traits::key_accessor key_accessor;
143 typedef typename base_class::node_type node_type;
148 typedef cds::gc::guarded_ptr< gc, node_type, value_type, details::guarded_ptr_cast_set<node_type, value_type> > guarded_ptr;
151 /// Forward iterator (see \p SplitListSet::iterator)
153 Remember, the iterator <tt>operator -> </tt> and <tt>operator *</tt> returns \ref value_type pointer and reference.
154 To access item key and value use <tt>it->first</tt> and <tt>it->second</tt> respectively.
156 typedef typename base_class::iterator iterator;
158 /// Const forward iterator (see SplitListSet::const_iterator)
159 typedef typename base_class::const_iterator const_iterator;
161 /// Returns a forward iterator addressing the first element in a map
163 For empty map \code begin() == end() \endcode
167 return base_class::begin();
170 /// Returns an iterator that addresses the location succeeding the last element in a map
172 Do not use the value returned by <tt>end</tt> function to access any item.
173 The returned value can be used only to control reaching the end of the map.
174 For empty map \code begin() == end() \endcode
178 return base_class::end();
181 /// Returns a forward const iterator addressing the first element in a map
183 const_iterator begin() const
185 return base_class::begin();
187 const_iterator cbegin() const
189 return base_class::cbegin();
193 /// Returns an const iterator that addresses the location succeeding the last element in a map
195 const_iterator end() const
197 return base_class::end();
199 const_iterator cend() const
201 return base_class::cend();
206 /// Initializes split-ordered map of default capacity
208 The default capacity is defined in bucket table constructor.
209 See \p intrusive::split_list::expandable_bucket_table, \p intrusive::split_list::static_bucket_table
210 which selects by \p intrusive::split_list::traits::dynamic_bucket_table.
216 /// Initializes split-ordered map
218 size_t nItemCount ///< estimated average item count
219 , size_t nLoadFactor = 1 ///< load factor - average item count per bucket. Small integer up to 10, default is 1.
221 : base_class( nItemCount, nLoadFactor )
225 /// Inserts new node with key and default value
227 The function creates a node with \p key and default value, and then inserts the node created into the map.
230 - The \ref key_type should be constructible from value of type \p K.
231 In trivial case, \p K is equal to \ref key_type.
232 - The \ref mapped_type should be default-constructible.
234 Returns \p true if inserting successful, \p false otherwise.
236 template <typename K>
237 bool insert( K const& key )
239 //TODO: pass arguments by reference (make_pair makes copy)
240 return base_class::insert( std::make_pair( key, mapped_type() ) );
245 The function creates a node with copy of \p val value
246 and then inserts the node created into the map.
249 - The \ref key_type should be constructible from \p key of type \p K.
250 - The \ref mapped_type should be constructible from \p val of type \p V.
252 Returns \p true if \p val is inserted into the map, \p false otherwise.
254 template <typename K, typename V>
255 bool insert( K const& key, V const& val )
257 //TODO: pass arguments by reference (make_pair makes copy)
258 return base_class::insert( std::make_pair(key, val) );
261 /// Inserts new node and initialize it by a functor
263 This function inserts new node with key \p key and if inserting is successful then it calls
264 \p func functor with signature
267 void operator()( value_type& item );
271 The argument \p item of user-defined functor \p func is the reference
272 to the map's item inserted:
273 - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
274 - <tt>item.second</tt> is a reference to item's value that may be changed.
276 It should be keep in mind that concurrent modifications of \p <tt>item.second</tt> may be possible.
278 The key_type should be constructible from value of type \p K.
280 The function allows to split creating of new item into two part:
281 - create item from \p key;
282 - insert new item into the map;
283 - if inserting is successful, initialize the value of item by calling \p func functor
285 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
286 it is preferable that the initialization should be completed only if inserting is successful.
288 @warning For \ref cds_nonintrusive_MichaelKVList_gc "MichaelKVList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
289 \ref cds_nonintrusive_LazyKVList_gc "LazyKVList" provides exclusive access to inserted item and does not require any node-level
292 template <typename K, typename Func>
293 bool insert_key( K const& key, Func func )
295 //TODO: pass arguments by reference (make_pair makes copy)
296 return base_class::insert( std::make_pair( key, mapped_type() ), func );
299 /// For key \p key inserts data of type \p mapped_type created from \p args
301 \p key_type should be constructible from type \p K
303 Returns \p true if inserting successful, \p false otherwise.
305 template <typename K, typename... Args>
306 bool emplace( K&& key, Args&&... args )
308 return base_class::emplace( std::forward<K>(key), std::move(mapped_type(std::forward<Args>(args)...)));
311 /// Ensures that the \p key exists in the map
313 The operation performs inserting or changing data with lock-free manner.
315 If the \p key not found in the map, then the new item created from \p key
316 is inserted into the map (note that in this case the \ref key_type should be
317 constructible from type \p K).
318 Otherwise, the functor \p func is called with item found.
319 The functor \p Func may be a function with signature:
321 void func( bool bNew, value_type& item );
326 void operator()( bool bNew, value_type& item );
331 - \p bNew - \p true if the item has been inserted, \p false otherwise
332 - \p item - item of the list
334 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
335 \p second is true if new item has been added or \p false if the item with \p key
336 already is in the list.
338 @warning For \ref cds_nonintrusive_MichaelKVList_gc "MichaelKVList" as the ordered list see \ref cds_intrusive_item_creating "insert item troubleshooting".
339 \ref cds_nonintrusive_LazyKVList_gc "LazyKVList" provides exclusive access to inserted item and does not require any node-level
342 template <typename K, typename Func>
343 std::pair<bool, bool> ensure( K const& key, Func func )
345 //TODO: pass arguments by reference (make_pair makes copy)
346 return base_class::ensure( std::make_pair( key, mapped_type() ),
347 [&func](bool bNew, value_type& item, value_type const& /*val*/) {
352 /// Deletes \p key from the map
353 /** \anchor cds_nonintrusive_SplitListMap_erase_val
355 Return \p true if \p key is found and deleted, \p false otherwise
357 template <typename K>
358 bool erase( K const& key )
360 return base_class::erase( key );
363 /// Deletes the item from the map using \p pred predicate for searching
365 The function is an analog of \ref cds_nonintrusive_SplitListMap_erase_val "erase(K const&)"
366 but \p pred is used for key comparing.
367 \p Less functor has the interface like \p std::less.
368 \p Less must imply the same element order as the comparator used for building the map.
370 template <typename K, typename Less>
371 bool erase_with( K const& key, Less pred )
373 return base_class::erase_with( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
376 /// Deletes \p key from the map
377 /** \anchor cds_nonintrusive_SplitListMap_erase_func
379 The function searches an item with key \p key, calls \p f functor
380 and deletes the item. If \p key is not found, the functor is not called.
382 The functor \p Func interface is:
385 void operator()(value_type& item) { ... }
389 Return \p true if key is found and deleted, \p false otherwise
391 template <typename K, typename Func>
392 bool erase( K const& key, Func f )
394 return base_class::erase( key, f );
397 /// Deletes the item from the map using \p pred predicate for searching
399 The function is an analog of \ref cds_nonintrusive_SplitListMap_erase_func "erase(K const&, Func)"
400 but \p pred is used for key comparing.
401 \p Less functor has the interface like \p std::less.
402 \p Less must imply the same element order as the comparator used for building the map.
404 template <typename K, typename Less, typename Func>
405 bool erase_with( K const& key, Less pred, Func f )
407 return base_class::erase_with( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>(), f );
410 /// Extracts the item with specified \p key
411 /** \anchor cds_nonintrusive_SplitListMap_hp_extract
412 The function searches an item with key equal to \p key,
413 unlinks it from the map, and returns it in \p dest parameter.
414 If the item with key equal to \p key is not found the function returns \p false.
416 Note the compare functor should accept a parameter of type \p K that may be not the same as \p value_type.
418 The extracted item is freed automatically when returned \ref guarded_ptr object will be destroyed or released.
419 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
423 typedef cds::container::SplitListMap< your_template_args > splitlist_map;
424 splitlist_map theMap;
427 splitlist_map::guarded_ptr gp;
428 theMap.extract( gp, 5 );
432 // Destructor of gp releases internal HP guard
436 template <typename K>
437 bool extract( guarded_ptr& dest, K const& key )
439 return base_class::extract_( dest.guard(), key );
442 /// Extracts the item using compare functor \p pred
444 The function is an analog of \ref cds_nonintrusive_SplitListMap_hp_extract "extract(guarded_ptr&, K const&)"
445 but \p pred predicate is used for key comparing.
447 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p K
449 \p pred must imply the same element order as the comparator used for building the map.
451 template <typename K, typename Less>
452 bool extract_with( guarded_ptr& dest, K const& key, Less pred )
454 return base_class::extract_with_( dest.guard(), key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
457 /// Finds the key \p key
458 /** \anchor cds_nonintrusive_SplitListMap_find_cfunc
460 The function searches the item with key equal to \p key and calls the functor \p f for item found.
461 The interface of \p Func functor is:
464 void operator()( value_type& item );
467 where \p item is the item found.
469 The functor may change \p item.second. Note that the functor is only guarantee
470 that \p item cannot be disposed during functor is executing.
471 The functor does not serialize simultaneous access to the map's \p item. If such access is
472 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
474 The function returns \p true if \p key is found, \p false otherwise.
476 template <typename K, typename Func>
477 bool find( K const& key, Func f )
479 return base_class::find( key, [&f](value_type& pair, K const&){ f( pair ); } );
482 /// Finds the key \p val using \p pred predicate for searching
484 The function is an analog of \ref cds_nonintrusive_SplitListMap_find_cfunc "find(K const&, Func)"
485 but \p pred is used for key comparing.
486 \p Less functor has the interface like \p std::less.
487 \p Less must imply the same element order as the comparator used for building the map.
489 template <typename K, typename Less, typename Func>
490 bool find_with( K const& key, Less pred, Func f )
492 return base_class::find_with( key,
493 cds::details::predicate_wrapper<value_type, Less, key_accessor>(),
494 [&f](value_type& pair, K const&){ f( pair ); } );
497 /// Finds the key \p key
498 /** \anchor cds_nonintrusive_SplitListMap_find_val
500 The function searches the item with key equal to \p key
501 and returns \p true if it is found, and \p false otherwise.
503 template <typename K>
504 bool find( K const& key )
506 return base_class::find( key );
509 /// Finds the key \p val using \p pred predicate for searching
511 The function is an analog of \ref cds_nonintrusive_SplitListMap_find_val "find(K const&)"
512 but \p pred is used for key comparing.
513 \p Less functor has the interface like \p std::less.
514 \p Less must imply the same element order as the comparator used for building the map.
516 template <typename K, typename Less>
517 bool find_with( K const& key, Less pred )
519 return base_class::find( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
522 /// Finds \p key and return the item found
523 /** \anchor cds_nonintrusive_SplitListMap_hp_get
524 The function searches the item with key equal to \p key
525 and assigns the item found to guarded pointer \p ptr.
526 The function returns \p true if \p key is found, and \p false otherwise.
527 If \p key is not found the \p ptr parameter is not changed.
529 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
533 typedef cds::container::SplitListMap< your_template_params > splitlist_map;
534 splitlist_map theMap;
537 splitlist_map::guarded_ptr gp;
538 if ( theMap.get( gp, 5 )) {
542 // Destructor of guarded_ptr releases internal HP guard
546 Note the compare functor specified for split-list map
547 should accept a parameter of type \p K that can be not the same as \p value_type.
549 template <typename K>
550 bool get( guarded_ptr& ptr, K const& key )
552 return base_class::get_( ptr.guard(), key );
555 /// Finds \p key and return the item found
557 The function is an analog of \ref cds_nonintrusive_SplitListMap_hp_get "get( guarded_ptr&, K const&)"
558 but \p pred is used for comparing the keys.
560 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p K
562 \p pred must imply the same element order as the comparator used for building the map.
564 template <typename K, typename Less>
565 bool get_with( guarded_ptr& ptr, K const& key, Less pred )
567 return base_class::get_with_( ptr.guard(), key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
570 /// Clears the map (not atomic)
576 /// Checks if the map is empty
578 Emptiness is checked by item counting: if item count is zero then the map is empty.
579 Thus, the correct item counting is an important part of the map implementation.
583 return base_class::empty();
586 /// Returns item count in the map
589 return base_class::size();
592 /// Returns internal statistics
593 stat const& statistics() const
595 return base_class::statistics();
600 }} // namespace cds::container
602 #endif // #ifndef __CDS_CONTAINER_SPLIT_LIST_MAP_H