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 - type traits, default is split_list::type_traits. Instead of declaring split_list::type_traits -based
26 struct you may apply option-based notation with 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 gc::HP GC
38 and MichaelList as ordered list implementation. Your map should map \p int key to <tt>std::string</tt> 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 for the map key and a comparing functor for 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 <tt>cds::contaner::michael_list_tag</tt> 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::type_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::type_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 SplitListMap:
73 typedef cc::SplitListMap< cds::gc::PTB, 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::PTB // 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 using 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 type_traits parts, optional ones is the default and they are inherited
98 from cds::container::split_list::type_traits.
99 The <b>cds</b> library contains many other options for deep tuning of behavior of the split-list and
100 ordered-list containers.
106 #ifdef CDS_DOXYGEN_INVOKED
107 class Traits = split_list::type_traits
113 protected container::SplitListSet<
115 std::pair<Key const, Value>,
116 split_list::details::wrap_map_traits<Key, Value, Traits>
120 typedef container::SplitListSet<
122 std::pair<Key const, Value>,
123 split_list::details::wrap_map_traits<Key, Value, Traits>
128 typedef typename base_class::gc gc ; ///< Garbage collector
129 typedef Key key_type ; ///< key type
130 typedef Value mapped_type ; ///< type of value stored in the map
131 typedef Traits options ; ///< \p Traits template argument
133 typedef std::pair<key_type const, mapped_type> value_type ; ///< key-value pair type
134 typedef typename base_class::ordered_list ordered_list; ///< Underlying ordered list class
135 typedef typename base_class::key_comparator key_comparator ; ///< key compare functor
137 typedef typename base_class::hash hash ; ///< Hash functor for \ref key_type
138 typedef typename base_class::item_counter item_counter ; ///< Item counter type
142 typedef typename base_class::maker::type_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 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()
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()
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 intrusive::split_list::expandable_bucket_table, intrusive::split_list::static_bucket_table
210 which selects by intrusive::split_list::dynamic_bucket_table option.
216 /// Initializes split-ordered map
218 size_t nItemCount ///< estimate 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.
277 User-defined functor \p func should guarantee that during changing item's value no any other changes
278 could be made on this \p item by concurrent threads.
280 The user-defined functor can be passed by reference using <tt>boost::ref</tt>
281 and it is called only if inserting is successful.
283 The key_type should be constructible from value of type \p K.
285 The function allows to split creating of new item into two part:
286 - create item from \p key;
287 - insert new item into the map;
288 - if inserting is successful, initialize the value of item by calling \p func functor
290 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
291 it is preferable that the initialization should be completed only if inserting is successful.
293 template <typename K, typename Func>
294 bool insert_key( K const& key, Func func )
296 //TODO: pass arguments by reference (make_pair makes copy)
297 return base_class::insert( std::make_pair( key, mapped_type() ), func );
300 /// For key \p key inserts data of type \ref mapped_type constructed with <tt>std::forward<Args>(args)...</tt>
302 \p key_type should be constructible from type \p K
304 Returns \p true if inserting successful, \p false otherwise.
306 template <typename K, typename... Args>
307 bool emplace( K&& key, Args&&... args )
309 return base_class::emplace( std::forward<K>(key), std::move(mapped_type(std::forward<Args>(args)...)));
312 /// Ensures that the \p key exists in the map
314 The operation performs inserting or changing data with lock-free manner.
316 If the \p key not found in the map, then the new item created from \p key
317 is inserted into the map (note that in this case the \ref key_type should be
318 constructible from type \p K).
319 Otherwise, the functor \p func is called with item found.
320 The functor \p Func may be a function with signature:
322 void func( bool bNew, value_type& item );
327 void operator()( bool bNew, value_type& item );
332 - \p bNew - \p true if the item has been inserted, \p false otherwise
333 - \p item - item of the list
335 The functor may change any fields of the \p item.second that is \ref mapped_type;
336 however, \p func must guarantee that during changing no any other modifications
337 could be made on this item by concurrent threads.
339 You may pass \p func argument by reference using <tt>boost::ref</tt>.
341 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
342 \p second is true if new item has been added or \p false if the item with \p key
343 already is in the list.
345 template <typename K, typename Func>
346 std::pair<bool, bool> ensure( K const& key, Func func )
348 //TODO: pass arguments by reference (make_pair makes copy)
349 return base_class::ensure( std::make_pair( key, mapped_type() ),
350 [&func](bool bNew, value_type& item, value_type const& /*val*/) {
351 cds::unref(func)( bNew, item );
355 /// Deletes \p key from the map
356 /** \anchor cds_nonintrusive_SplitListMap_erase_val
358 Return \p true if \p key is found and deleted, \p false otherwise
360 template <typename K>
361 bool erase( K const& key )
363 return base_class::erase( key );
366 /// Deletes the item from the map using \p pred predicate for searching
368 The function is an analog of \ref cds_nonintrusive_SplitListMap_erase_val "erase(K const&)"
369 but \p pred is used for key comparing.
370 \p Less functor has the interface like \p std::less.
371 \p Less must imply the same element order as the comparator used for building the map.
373 template <typename K, typename Less>
374 bool erase_with( K const& key, Less pred )
376 return base_class::erase_with( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
379 /// Deletes \p key from the map
380 /** \anchor cds_nonintrusive_SplitListMap_erase_func
382 The function searches an item with key \p key, calls \p f functor
383 and deletes the item. If \p key is not found, the functor is not called.
385 The functor \p Func interface is:
388 void operator()(value_type& item) { ... }
391 The functor may be passed by reference using <tt>boost:ref</tt>
393 Return \p true if key is found and deleted, \p false otherwise
395 template <typename K, typename Func>
396 bool erase( K const& key, Func f )
398 return base_class::erase( key, f );
401 /// Deletes the item from the map using \p pred predicate for searching
403 The function is an analog of \ref cds_nonintrusive_SplitListMap_erase_func "erase(K const&, Func)"
404 but \p pred is used for key comparing.
405 \p Less functor has the interface like \p std::less.
406 \p Less must imply the same element order as the comparator used for building the map.
408 template <typename K, typename Less, typename Func>
409 bool erase_with( K const& key, Less pred, Func f )
411 return base_class::erase_with( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>(), f );
414 /// Extracts the item with specified \p key
415 /** \anchor cds_nonintrusive_SplitListMap_hp_extract
416 The function searches an item with key equal to \p key,
417 unlinks it from the map, and returns it in \p dest parameter.
418 If the item with key equal to \p key is not found the function returns \p false.
420 Note the compare functor should accept a parameter of type \p K that may be not the same as \p value_type.
422 The extracted item is freed automatically when returned \ref guarded_ptr object will be destroyed or released.
423 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
427 typedef cds::container::SplitListMap< your_template_args > splitlist_map;
428 splitlist_map theMap;
431 splitlist_map::guarded_ptr gp;
432 theMap.extract( gp, 5 );
436 // Destructor of gp releases internal HP guard
440 template <typename K>
441 bool extract( guarded_ptr& dest, K const& key )
443 return base_class::extract_( dest.guard(), key );
446 /// Extracts the item using compare functor \p pred
448 The function is an analog of \ref cds_nonintrusive_SplitListMap_hp_extract "extract(guarded_ptr&, K const&)"
449 but \p pred predicate is used for key comparing.
451 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p K
453 \p pred must imply the same element order as the comparator used for building the map.
455 template <typename K, typename Less>
456 bool extract_with( guarded_ptr& dest, K const& key, Less pred )
458 return base_class::extract_with_( dest.guard(), key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
461 /// Finds the key \p key
462 /** \anchor cds_nonintrusive_SplitListMap_find_cfunc
464 The function searches the item with key equal to \p key and calls the functor \p f for item found.
465 The interface of \p Func functor is:
468 void operator()( value_type& item );
471 where \p item is the item found.
473 You may pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
475 The functor may change \p item.second. Note that the functor is only guarantee
476 that \p item cannot be disposed during functor is executing.
477 The functor does not serialize simultaneous access to the map's \p item. If such access is
478 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
480 The function returns \p true if \p key is found, \p false otherwise.
482 template <typename K, typename Func>
483 bool find( K const& key, Func f )
485 return base_class::find( key, [&f](value_type& pair, K const&){ cds::unref(f)( pair ); } );
488 /// Finds the key \p val using \p pred predicate for searching
490 The function is an analog of \ref cds_nonintrusive_SplitListMap_find_cfunc "find(K const&, Func)"
491 but \p pred is used for key comparing.
492 \p Less functor has the interface like \p std::less.
493 \p Less must imply the same element order as the comparator used for building the map.
495 template <typename K, typename Less, typename Func>
496 bool find_with( K const& key, Less pred, Func f )
498 return base_class::find_with( key,
499 cds::details::predicate_wrapper<value_type, Less, key_accessor>(),
500 [&f](value_type& pair, K const&){ cds::unref(f)( pair ); } );
503 /// Finds the key \p key
504 /** \anchor cds_nonintrusive_SplitListMap_find_val
506 The function searches the item with key equal to \p key
507 and returns \p true if it is found, and \p false otherwise.
509 template <typename K>
510 bool find( K const& key )
512 return base_class::find( key );
515 /// Finds the key \p val using \p pred predicate for searching
517 The function is an analog of \ref cds_nonintrusive_SplitListMap_find_val "find(K const&)"
518 but \p pred is used for key comparing.
519 \p Less functor has the interface like \p std::less.
520 \p Less must imply the same element order as the comparator used for building the map.
522 template <typename K, typename Less>
523 bool find_with( K const& key, Less pred )
525 return base_class::find( key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
528 /// Finds \p key and return the item found
529 /** \anchor cds_nonintrusive_SplitListMap_hp_get
530 The function searches the item with key equal to \p key
531 and assigns the item found to guarded pointer \p ptr.
532 The function returns \p true if \p key is found, and \p false otherwise.
533 If \p key is not found the \p ptr parameter is not changed.
535 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
539 typedef cds::container::SplitListMap< your_template_params > splitlist_map;
540 splitlist_map theMap;
543 splitlist_map::guarded_ptr gp;
544 if ( theMap.get( gp, 5 )) {
548 // Destructor of guarded_ptr releases internal HP guard
552 Note the compare functor specified for split-list map
553 should accept a parameter of type \p K that can be not the same as \p value_type.
555 template <typename K>
556 bool get( guarded_ptr& ptr, K const& key )
558 return base_class::get_( ptr.guard(), key );
561 /// Finds \p key and return the item found
563 The function is an analog of \ref cds_nonintrusive_SplitListMap_hp_get "get( guarded_ptr&, K const&)"
564 but \p pred is used for comparing the keys.
566 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p K
568 \p pred must imply the same element order as the comparator used for building the map.
570 template <typename K, typename Less>
571 bool get_with( guarded_ptr& ptr, K const& key, Less pred )
573 return base_class::get_with_( ptr.guard(), key, cds::details::predicate_wrapper<value_type, Less, key_accessor>() );
576 /// Clears the map (non-atomic)
578 The function unlink all items from the map.
579 The function is not atomic and not lock-free and should be used for debugging only.
586 /// Checks if the map is empty
588 Emptiness is checked by item counting: if item count is zero then the map is empty.
589 Thus, the correct item counting is an important part of the map implementation.
593 return base_class::empty();
596 /// Returns item count in the map
599 return base_class::size();
604 }} // namespace cds::container
606 #endif // #ifndef __CDS_CONTAINER_SPLIT_LIST_MAP_H