3 #ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H
4 #define __CDS_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
103 typedef typename base_class::value_type leaf_node;
104 typedef typename base_class::internal_node internal_node;
105 typedef typename base_class::update_desc update_desc;
107 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
109 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
114 typedef typename gc::template guarded_ptr< leaf_node, value_type, details::guarded_ptr_cast_set<leaf_node, value_type> > guarded_ptr;
117 /// Default constructor
126 /// Inserts new node with key and default value
128 The function creates a node with \p key and default value, and then inserts the node created into the map.
131 - The \ref key_type should be constructible from a value of type \p K.
132 In trivial case, \p K is equal to \ref key_type.
133 - The \ref mapped_type should be default-constructible.
135 Returns \p true if inserting successful, \p false otherwise.
137 template <typename K>
138 bool insert( K const& key )
140 return insert_with( key, [](value_type&){} );
145 The function creates a node with copy of \p val value
146 and then inserts the node created into the map.
149 - The \p key_type should be constructible from \p key of type \p K.
150 - The \p value_type should be constructible from \p val of type \p V.
152 Returns \p true if \p val is inserted into the map, \p false otherwise.
154 template <typename K, typename V>
155 bool insert( K const& key, V const& val )
157 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key, val ));
158 if ( base_class::insert( *pNode ))
166 /// Inserts new node and initialize it by a functor
168 This function inserts new node with key \p key and if inserting is successful then it calls
169 \p func functor with signature
172 void operator()( value_type& item );
176 The argument \p item of user-defined functor \p func is the reference
177 to the map's item inserted:
178 - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
179 - <tt>item.second</tt> is a reference to item's value that may be changed.
181 The key_type should be constructible from value of type \p K.
183 The function allows to split creating of new item into two part:
184 - create item from \p key;
185 - insert new item into the map;
186 - if inserting is successful, initialize the value of item by calling \p func functor
188 This can be useful if complete initialization of object of \p value_type is heavyweight and
189 it is preferable that the initialization should be completed only if inserting is successful.
191 template <typename K, typename Func>
192 bool insert_with( const K& key, Func func )
194 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
195 if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { func( item.m_Value ); } )) {
202 /// For key \p key inserts data of type \p value_type created in-place from \p args
204 Returns \p true if inserting successful, \p false otherwise.
206 template <typename K, typename... Args>
207 bool emplace( K&& key, Args&&... args )
209 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
210 if ( base_class::insert( *pNode )) {
217 /// Ensures that the \p key exists in the map
219 The operation performs inserting or changing data with lock-free manner.
221 If the \p key not found in the map, then the new item created from \p key
222 is inserted into the map (note that in this case the \ref key_type should be
223 constructible from type \p K).
224 Otherwise, the functor \p func is called with item found.
225 The functor \p Func may be a function with signature:
227 void func( bool bNew, value_type& item );
232 void operator()( bool bNew, value_type& item );
237 - \p bNew - \p true if the item has been inserted, \p false otherwise
238 - \p item - item of the list
240 The functor may change any fields of the \p item.second that is \ref value_type.
242 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
243 \p second is true if new item has been added or \p false if the item with \p key
244 already is in the list.
246 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
248 template <typename K, typename Func>
249 std::pair<bool, bool> ensure( K const& key, Func func )
251 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
252 std::pair<bool, bool> res = base_class::ensure( *pNode,
253 [&func](bool bNew, leaf_node& item, leaf_node const& ){ func( bNew, item.m_Value ); }
255 if ( res.first && res.second )
260 /// Delete \p key from the map
261 /**\anchor cds_nonintrusive_EllenBinTreeMap_erase_val
263 Return \p true if \p key is found and deleted, \p false otherwise
265 template <typename K>
266 bool erase( K const& key )
268 return base_class::erase(key);
271 /// Deletes the item from the map using \p pred predicate for searching
273 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_val "erase(K const&)"
274 but \p pred is used for key comparing.
275 \p Less functor has the interface like \p std::less.
276 \p Less must imply the same element order as the comparator used for building the map.
278 template <typename K, typename Less>
279 bool erase_with( K const& key, Less pred )
282 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
285 /// Delete \p key from the map
286 /** \anchor cds_nonintrusive_EllenBinTreeMap_erase_func
288 The function searches an item with key \p key, calls \p f functor
289 and deletes the item. If \p key is not found, the functor is not called.
291 The functor \p Func interface:
294 void operator()(value_type& item) { ... }
298 Return \p true if key is found and deleted, \p false otherwise
300 template <typename K, typename Func>
301 bool erase( K const& key, Func f )
303 return base_class::erase( key, [&f]( leaf_node& node) { f( node.m_Value ); } );
306 /// Deletes the item from the map using \p pred predicate for searching
308 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_erase_func "erase(K const&, Func)"
309 but \p pred is used for key comparing.
310 \p Less functor has the interface like \p std::less.
311 \p Less must imply the same element order as the comparator used for building the map.
313 template <typename K, typename Less, typename Func>
314 bool erase_with( K const& key, Less pred, Func f )
317 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
318 [&f]( leaf_node& node) { f( node.m_Value ); } );
321 /// Extracts an item with minimal key from the map
323 If the map is not empty, the function returns an guarded pointer to minimum value.
324 If the map is empty, the function returns an empty \p guarded_ptr.
326 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
327 It means that the function gets leftmost leaf of the tree and tries to unlink it.
328 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
329 So, the function returns the item with minimum key at the moment of tree traversing.
331 The guarded pointer prevents deallocation of returned item,
332 see \p cds::gc::guarded_ptr for explanation.
333 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
335 guarded_ptr extract_min()
338 base_class::extract_min_( gp.guard() );
342 /// Extracts an item with maximal key from the map
344 If the map is not empty, the function returns a guarded pointer to maximal value.
345 If the map is empty, the function returns an empty \p guarded_ptr.
347 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
348 It means that the function gets rightmost leaf of the tree and tries to unlink it.
349 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
350 So, the function returns the item with maximum key at the moment of tree traversing.
352 The guarded pointer prevents deallocation of returned item,
353 see \p cds::gc::guarded_ptr for explanation.
354 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
356 guarded_ptr extract_max()
359 base_class::extract_max_( gp.guard() );
363 /// Extracts an item from the tree
364 /** \anchor cds_nonintrusive_EllenBinTreeMap_extract
365 The function searches an item with key equal to \p key in the tree,
366 unlinks it, and returns a guarded pointer to an item found.
367 If the item is not found the function returns an empty \p guarded_ptr.
369 The guarded pointer prevents deallocation of returned item,
370 see \p cds::gc::guarded_ptr for explanation.
371 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
373 template <typename Q>
374 guarded_ptr extract( Q const& key )
377 base_class::extract_( gp.guard(), key );
381 /// Extracts an item from the map using \p pred for searching
383 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_extract "extract(Q const&)"
384 but \p pred is used for key compare.
385 \p Less has the interface like \p std::less.
386 \p pred must imply the same element order as the comparator used for building the map.
388 template <typename Q, typename Less>
389 guarded_ptr extract_with( Q const& key, Less pred )
393 base_class::extract_with_( gp.guard(), key,
394 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
398 /// Find the key \p key
399 /** \anchor cds_nonintrusive_EllenBinTreeMap_find_cfunc
401 The function searches the item with key equal to \p key and calls the functor \p f for item found.
402 The interface of \p Func functor is:
405 void operator()( value_type& item );
408 where \p item is the item found.
410 The functor may change \p item.second.
412 The function returns \p true if \p key is found, \p false otherwise.
414 template <typename K, typename Func>
415 bool find( K const& key, Func f )
417 return base_class::find( key, [&f](leaf_node& item, K const& ) { f( item.m_Value );});
420 /// Finds the key \p val using \p pred predicate for searching
422 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_cfunc "find(K const&, Func)"
423 but \p pred is used for key comparing.
424 \p Less functor has the interface like \p std::less.
425 \p Less must imply the same element order as the comparator used for building the map.
427 template <typename K, typename Less, typename Func>
428 bool find_with( K const& key, Less pred, Func f )
431 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
432 [&f](leaf_node& item, K const& ) { f( item.m_Value );});
435 /// Find the key \p key
436 /** \anchor cds_nonintrusive_EllenBinTreeMap_find_val
438 The function searches the item with key equal to \p key
439 and returns \p true if it is found, and \p false otherwise.
441 template <typename K>
442 bool find( K const& key )
444 return base_class::find( key );
447 /// Finds the key \p val using \p pred predicate for searching
449 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_find_val "find(K const&)"
450 but \p pred is used for key comparing.
451 \p Less functor has the interface like \p std::less.
452 \p Less must imply the same element order as the comparator used for building the map.
454 template <typename K, typename Less>
455 bool find_with( K const& key, Less pred )
458 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
461 /// Finds \p key and returns the item found
462 /** @anchor cds_nonintrusive_EllenBinTreeMap_get
463 The function searches the item with key equal to \p key and returns the item found as a guarded pointer.
464 If \p key is not foudn the function returns an empty \p guarded_ptr.
466 The guarded pointer prevents deallocation of returned item,
467 see \p cds::gc::guarded_ptr for explanation.
468 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
470 template <typename Q>
471 guarded_ptr get( Q const& key )
474 base_class::get_( gp.guard(), key );
478 /// Finds \p key with predicate \p pred and returns the item found
480 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_get "get(Q const&)"
481 but \p pred is used for key comparing.
482 \p Less functor has the interface like \p std::less.
483 \p pred must imply the same element order as the comparator used for building the map.
485 template <typename Q, typename Less>
486 guarded_ptr get_with( Q const& key, Less pred )
490 base_class::get_with_( gp.guard(), key,
491 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
495 /// Clears the map (not atomic)
501 /// Checks if the map is empty
503 Emptiness is checked by item counting: if item count is zero then the map is empty.
507 return base_class::empty();
510 /// Returns item count in the set
512 Only leaf nodes containing user data are counted.
514 The value returned depends on item counter type provided by \p Traits template parameter.
515 If it is \p atomicity::empty_item_counter this function always returns 0.
517 The function is not suitable for checking the tree emptiness, use \p empty()
518 member function for this purpose.
522 return base_class::size();
525 /// Returns const reference to internal statistics
526 stat const& statistics() const
528 return base_class::statistics();
531 /// Checks internal consistency (not atomic, not thread-safe)
533 The debugging function to check internal consistency of the tree.
535 bool check_consistency() const
537 return base_class::check_consistency();
541 }} // namespace cds::container
543 #endif //#ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_MAP_H