3 #ifndef CDSLIB_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H
4 #define CDSLIB_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H
7 #include <cds/container/details/ellen_bintree_base.h>
8 #include <cds/intrusive/impl/ellen_bintree.h>
9 #include <cds/container/details/guarded_ptr_cast.h>
11 namespace cds { namespace container {
13 /// Map based on Ellen's et al binary search tree
14 /** @ingroup cds_nonintrusive_map
15 @ingroup cds_nonintrusive_tree
16 @anchor cds_container_EllenBinTreeMap
19 - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"
21 %EllenBinTreeMap is an unbalanced leaf-oriented binary search tree that implements the <i>map</i>
22 abstract data type. Nodes maintains child pointers but not parent pointers.
23 Every internal node has exactly two children, and all data of type <tt>std::pair<Key const, T></tt>
24 currently in the tree are stored in the leaves. Internal nodes of the tree are used to direct \p find
25 operation along the path to the correct leaf. The keys (of \p Key type) stored in internal nodes
26 may or may not be in the map.
27 Unlike \ref cds_container_EllenBinTreeSet "EllenBinTreeSet" keys are not a part of \p T type.
28 The map can be represented as a set containing <tt>std::pair< Key const, T> </tt> values.
30 Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeMap can act as
31 a <i>priority queue</i>. In this case you should provide unique compound key, for example,
32 the priority value plus some uniformly distributed random value.
34 @warning Recall the tree is <b>unbalanced</b>. The complexity of operations is <tt>O(log N)</tt>
35 for uniformly distributed random keys, but in worst case the complexity is <tt>O(N)</tt>.
37 @note In the current implementation we do not use helping technique described in the original paper.
38 In Hazard Pointer schema helping is too complicated and does not give any observable benefits.
39 Instead of helping, when a thread encounters a concurrent operation it just spins waiting for
40 the operation done. Such solution allows greatly simplify implementation of the tree.
42 <b>Template arguments</b> :
43 - \p GC - safe memory reclamation (i.e. light-weight garbage collector) type, like \p cds::gc::HP, \p cds::gc::DHP
45 - \p T - value type to be stored in tree's leaf nodes.
46 - \p Traits - map traits, default is \p ellen_bintree::traits
47 It is possible to declare option-based tree with \p ellen_bintree::make_map_traits metafunction
48 instead of \p Traits template argument.
50 @note Do not include <tt><cds/container/impl/ellen_bintree_map.h></tt> header file directly.
51 There are header file for each GC type:
52 - <tt><cds/container/ellen_bintree_map_hp.h></tt> - for Hazard Pointer GC cds::gc::HP
53 - <tt><cds/container/ellen_bintree_map_dhp.h></tt> - for Dynamic Hazard Pointer GC cds::gc::DHP
54 - <tt><cds/container/ellen_bintree_map_rcu.h></tt> - for RCU GC
55 (see \ref cds_container_EllenBinTreeMap_rcu "RCU-based EllenBinTreeMap")
61 #ifdef CDS_DOXYGEN_INVOKED
62 class Traits = ellen_bintree::traits
68 #ifdef CDS_DOXYGEN_INVOKED
69 : public cds::intrusive::EllenBinTree< GC, Key, T, Traits >
71 : public ellen_bintree::details::make_ellen_bintree_map< GC, Key, T, Traits >::type
75 typedef ellen_bintree::details::make_ellen_bintree_map< GC, Key, T, Traits > maker;
76 typedef typename maker::type base_class;
79 typedef GC gc; ///< Garbage collector
80 typedef Key key_type; ///< type of a key stored in the map
81 typedef T mapped_type; ///< type of value stored in the map
82 typedef std::pair< key_type const, mapped_type > value_type ; ///< Key-value pair stored in leaf node of the mp
83 typedef Traits traits; ///< Map traits
85 # ifdef CDS_DOXYGEN_INVOKED
86 typedef implementation_defined key_comparator; ///< key compare functor based on \p Traits::compare and \p Traits::less
88 typedef typename maker::intrusive_traits::compare key_comparator;
90 typedef typename base_class::item_counter item_counter; ///< Item counting policy
91 typedef typename base_class::memory_model memory_model; ///< Memory ordering, see \p cds::opt::memory_model
92 typedef typename base_class::node_allocator node_allocator_type; ///< allocator for maintaining internal node
93 typedef typename base_class::stat stat; ///< internal statistics type
94 typedef typename traits::copy_policy copy_policy; ///< key copy policy
95 typedef typename traits::back_off back_off; ///< Back-off strategy
97 typedef typename traits::allocator allocator_type; ///< Allocator for leaf nodes
98 typedef typename base_class::node_allocator node_allocator; ///< Internal node allocator
99 typedef typename base_class::update_desc_allocator update_desc_allocator; ///< Update descriptor allocator
102 typedef cds::container::ellen_bintree::implementation_tag implementation_tag;
107 typedef typename base_class::value_type leaf_node;
108 typedef typename base_class::internal_node internal_node;
109 typedef typename base_class::update_desc update_desc;
111 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
113 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
118 typedef typename gc::template guarded_ptr< leaf_node, value_type, details::guarded_ptr_cast_set<leaf_node, value_type> > guarded_ptr;
121 /// Default constructor
130 /// Inserts new node with key and default value
132 The function creates a node with \p key and default value, and then inserts the node created into the map.
135 - The \ref key_type should be constructible from a value of type \p K.
136 In trivial case, \p K is equal to \ref key_type.
137 - The \ref mapped_type should be default-constructible.
139 Returns \p true if inserting successful, \p false otherwise.
141 template <typename K>
142 bool insert( K const& key )
144 return insert_with( key, [](value_type&){} );
149 The function creates a node with copy of \p val value
150 and then inserts the node created into the map.
153 - The \p key_type should be constructible from \p key of type \p K.
154 - The \p value_type should be constructible from \p val of type \p V.
156 Returns \p true if \p val is inserted into the map, \p false otherwise.
158 template <typename K, typename V>
159 bool insert( K const& key, V const& val )
161 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key, val ));
162 if ( base_class::insert( *pNode ))
170 /// Inserts new node and initialize it by a functor
172 This function inserts new node with key \p key and if inserting is successful then it calls
173 \p func functor with signature
176 void operator()( value_type& item );
180 The argument \p item of user-defined functor \p func is the reference
181 to the map's item inserted:
182 - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
183 - <tt>item.second</tt> is a reference to item's value that may be changed.
185 The key_type should be constructible from value of type \p K.
187 The function allows to split creating of new item into two part:
188 - create item from \p key;
189 - insert new item into the map;
190 - if inserting is successful, initialize the value of item by calling \p func functor
192 This can be useful if complete initialization of object of \p value_type is heavyweight and
193 it is preferable that the initialization should be completed only if inserting is successful.
195 template <typename K, typename Func>
196 bool insert_with( const K& key, Func func )
198 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
199 if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { func( item.m_Value ); } )) {
206 /// For key \p key inserts data of type \p value_type created in-place from \p args
208 Returns \p true if inserting successful, \p false otherwise.
210 template <typename K, typename... Args>
211 bool emplace( K&& key, Args&&... args )
213 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
214 if ( base_class::insert( *pNode )) {
221 /// Ensures that the \p key exists in the map
223 The operation performs inserting or changing data with lock-free manner.
225 If the \p key not found in the map, then the new item created from \p key
226 is inserted into the map (note that in this case the \ref key_type should be
227 constructible from type \p K).
228 Otherwise, the functor \p func is called with item found.
229 The functor \p Func may be a function with signature:
231 void func( bool bNew, value_type& item );
236 void operator()( bool bNew, value_type& item );
241 - \p bNew - \p true if the item has been inserted, \p false otherwise
242 - \p item - item of the list
244 The functor may change any fields of the \p item.second that is \ref value_type.
246 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
247 \p second is true if new item has been added or \p false if the item with \p key
248 already is in the list.
250 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
252 template <typename K, typename Func>
253 std::pair<bool, bool> ensure( K const& key, Func func )
255 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
256 std::pair<bool, bool> res = base_class::ensure( *pNode,
257 [&func](bool bNew, leaf_node& item, leaf_node const& ){ func( bNew, item.m_Value ); }
259 if ( res.first && res.second )
264 /// Delete \p key from the map
265 /**\anchor cds_nonintrusive_EllenBinTreeMap_erase_val
267 Return \p true if \p key is found and deleted, \p false otherwise
269 template <typename K>
270 bool erase( K const& key )
272 return base_class::erase(key);
275 /// Deletes the item from the map using \p pred predicate for searching
277 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_val "erase(K const&)"
278 but \p pred is used for key comparing.
279 \p Less functor has the interface like \p std::less.
280 \p Less must imply the same element order as the comparator used for building the map.
282 template <typename K, typename Less>
283 bool erase_with( K const& key, Less pred )
286 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
289 /// Delete \p key from the map
290 /** \anchor cds_nonintrusive_EllenBinTreeMap_erase_func
292 The function searches an item with key \p key, calls \p f functor
293 and deletes the item. If \p key is not found, the functor is not called.
295 The functor \p Func interface:
298 void operator()(value_type& item) { ... }
302 Return \p true if key is found and deleted, \p false otherwise
304 template <typename K, typename Func>
305 bool erase( K const& key, Func f )
307 return base_class::erase( key, [&f]( leaf_node& node) { f( node.m_Value ); } );
310 /// Deletes the item from the map using \p pred predicate for searching
312 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_func "erase(K const&, Func)"
313 but \p pred is used for key comparing.
314 \p Less functor has the interface like \p std::less.
315 \p Less must imply the same element order as the comparator used for building the map.
317 template <typename K, typename Less, typename Func>
318 bool erase_with( K const& key, Less pred, Func f )
321 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
322 [&f]( leaf_node& node) { f( node.m_Value ); } );
325 /// Extracts an item with minimal key from the map
327 If the map is not empty, the function returns an guarded pointer to minimum value.
328 If the map is empty, the function returns an empty \p guarded_ptr.
330 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
331 It means that the function gets leftmost leaf of the tree and tries to unlink it.
332 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
333 So, the function returns the item with minimum key at the moment of tree traversing.
335 The guarded pointer prevents deallocation of returned item,
336 see \p cds::gc::guarded_ptr for explanation.
337 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
339 guarded_ptr extract_min()
342 base_class::extract_min_( gp.guard() );
346 /// Extracts an item with maximal key from the map
348 If the map is not empty, the function returns a guarded pointer to maximal value.
349 If the map is empty, the function returns an empty \p guarded_ptr.
351 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
352 It means that the function gets rightmost leaf of the tree and tries to unlink it.
353 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
354 So, the function returns the item with maximum key at the moment of tree traversing.
356 The guarded pointer prevents deallocation of returned item,
357 see \p cds::gc::guarded_ptr for explanation.
358 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
360 guarded_ptr extract_max()
363 base_class::extract_max_( gp.guard() );
367 /// Extracts an item from the tree
368 /** \anchor cds_nonintrusive_EllenBinTreeMap_extract
369 The function searches an item with key equal to \p key in the tree,
370 unlinks it, and returns a guarded pointer to an item found.
371 If the item is not found the function returns an empty \p guarded_ptr.
373 The guarded pointer prevents deallocation of returned item,
374 see \p cds::gc::guarded_ptr for explanation.
375 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
377 template <typename Q>
378 guarded_ptr extract( Q const& key )
381 base_class::extract_( gp.guard(), key );
385 /// Extracts an item from the map using \p pred for searching
387 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_extract "extract(Q const&)"
388 but \p pred is used for key compare.
389 \p Less has the interface like \p std::less.
390 \p pred must imply the same element order as the comparator used for building the map.
392 template <typename Q, typename Less>
393 guarded_ptr extract_with( Q const& key, Less pred )
397 base_class::extract_with_( gp.guard(), key,
398 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
402 /// Find the key \p key
403 /** \anchor cds_nonintrusive_EllenBinTreeMap_find_cfunc
405 The function searches the item with key equal to \p key and calls the functor \p f for item found.
406 The interface of \p Func functor is:
409 void operator()( value_type& item );
412 where \p item is the item found.
414 The functor may change \p item.second.
416 The function returns \p true if \p key is found, \p false otherwise.
418 template <typename K, typename Func>
419 bool find( K const& key, Func f )
421 return base_class::find( key, [&f](leaf_node& item, K const& ) { f( item.m_Value );});
424 /// Finds the key \p val using \p pred predicate for searching
426 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_cfunc "find(K const&, Func)"
427 but \p pred is used for key comparing.
428 \p Less functor has the interface like \p std::less.
429 \p Less must imply the same element order as the comparator used for building the map.
431 template <typename K, typename Less, typename Func>
432 bool find_with( K const& key, Less pred, Func f )
435 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
436 [&f](leaf_node& item, K const& ) { f( item.m_Value );});
439 /// Find the key \p key
440 /** \anchor cds_nonintrusive_EllenBinTreeMap_find_val
442 The function searches the item with key equal to \p key
443 and returns \p true if it is found, and \p false otherwise.
445 template <typename K>
446 bool find( K const& key )
448 return base_class::find( key );
451 /// Finds the key \p val using \p pred predicate for searching
453 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_val "find(K const&)"
454 but \p pred is used for key comparing.
455 \p Less functor has the interface like \p std::less.
456 \p Less must imply the same element order as the comparator used for building the map.
458 template <typename K, typename Less>
459 bool find_with( K const& key, Less pred )
462 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
465 /// Finds \p key and returns the item found
466 /** @anchor cds_nonintrusive_EllenBinTreeMap_get
467 The function searches the item with key equal to \p key and returns the item found as a guarded pointer.
468 If \p key is not foudn the function returns an empty \p guarded_ptr.
470 The guarded pointer prevents deallocation of returned item,
471 see \p cds::gc::guarded_ptr for explanation.
472 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
474 template <typename Q>
475 guarded_ptr get( Q const& key )
478 base_class::get_( gp.guard(), key );
482 /// Finds \p key with predicate \p pred and returns the item found
484 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_get "get(Q const&)"
485 but \p pred is used for key comparing.
486 \p Less functor has the interface like \p std::less.
487 \p pred must imply the same element order as the comparator used for building the map.
489 template <typename Q, typename Less>
490 guarded_ptr get_with( Q const& key, Less pred )
494 base_class::get_with_( gp.guard(), key,
495 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
499 /// Clears the map (not atomic)
505 /// Checks if the map is empty
507 Emptiness is checked by item counting: if item count is zero then the map is empty.
511 return base_class::empty();
514 /// Returns item count in the set
516 Only leaf nodes containing user data are counted.
518 The value returned depends on item counter type provided by \p Traits template parameter.
519 If it is \p atomicity::empty_item_counter this function always returns 0.
521 The function is not suitable for checking the tree emptiness, use \p empty()
522 member function for this purpose.
526 return base_class::size();
529 /// Returns const reference to internal statistics
530 stat const& statistics() const
532 return base_class::statistics();
535 /// Checks internal consistency (not atomic, not thread-safe)
537 The debugging function to check internal consistency of the tree.
539 bool check_consistency() const
541 return base_class::check_consistency();
545 }} // namespace cds::container
547 #endif //#ifndef CDSLIB_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H