3 #ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_SET_H
4 #define __CDS_CONTAINER_IMPL_ELLEN_BINTREE_SET_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 /// Set based on Ellen's et al binary search tree
14 /** @ingroup cds_nonintrusive_set
15 @ingroup cds_nonintrusive_tree
16 @anchor cds_container_EllenBinTreeSet
19 - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"
21 %EllenBinTreeSet is an unbalanced leaf-oriented binary search tree that implements the <i>set</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 \p T currently in
24 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 set. \p Key type is a subset of \p T type.
27 There should be exactly defined a key extracting functor for converting object of type \p T to
28 object of type \p Key.
30 Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeSet 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 the implementation of tree.
42 <b>Template arguments</b> :
43 - \p GC - safe memory reclamation (i.e. light-weight garbage collector) type, like \p cds::gc::HP, cds::gc::DHP
44 - \p Key - key type, a subset of \p T
45 - \p T - type to be stored in tree's leaf nodes.
46 - \p Traits - set traits, default is \p ellen_bintree::traits
47 It is possible to declare option-based tree with \p ellen_bintree::make_set_traits metafunction
48 instead of \p Traits template argument.
50 @note Do not include <tt><cds/container/impl/ellen_bintree_set.h></tt> header file directly.
51 There are header file for each GC type:
52 - <tt><cds/container/ellen_bintree_set_hp.h></tt> - for \p cds::gc::HP
53 - <tt><cds/container/ellen_bintree_set_dhp.h></tt> - for \p cds::gc::DHP
54 - <tt><cds/container/ellen_bintree_set_rcu.h></tt> - for RCU GC
55 (see \ref cds_container_EllenBinTreeSet_rcu "RCU-based EllenBinTreeSet")
57 @anchor cds_container_EllenBinTreeSet_less
58 <b>Predicate requirements</b>
60 \p Traits::less, \p Traits::compare and other predicates using with member fuctions should accept at least parameters
61 of type \p T and \p Key in any combination.
62 For example, for \p Foo struct with \p std::string key field the appropiate \p less functor is:
71 bool operator()( Foo const& v1, Foo const& v2 ) const
72 { return v1.m_strKey < v2.m_strKey ; }
74 bool operator()( Foo const& v, std::string const& s ) const
75 { return v.m_strKey < s ; }
77 bool operator()( std::string const& s, Foo const& v ) const
78 { return s < v.m_strKey ; }
80 // Support comparing std::string and char const *
81 bool operator()( std::string const& s, char const * p ) const
82 { return s.compare(p) < 0 ; }
84 bool operator()( Foo const& v, char const * p ) const
85 { return v.m_strKey.compare(p) < 0 ; }
87 bool operator()( char const * p, std::string const& s ) const
88 { return s.compare(p) > 0; }
90 bool operator()( char const * p, Foo const& v ) const
91 { return v.m_strKey.compare(p) > 0; }
99 #ifdef CDS_DOXYGEN_INVOKED
100 class Traits = ellen_bintree::traits
105 class EllenBinTreeSet
106 #ifdef CDS_DOXYGEN_INVOKED
107 : public cds::intrusive::EllenBinTree< GC, Key, T, Traits >
109 : public ellen_bintree::details::make_ellen_bintree_set< GC, Key, T, Traits >::type
113 typedef ellen_bintree::details::make_ellen_bintree_set< GC, Key, T, Traits > maker;
114 typedef typename maker::type base_class;
118 typedef GC gc; ///< Garbage collector
119 typedef Key key_type; ///< type of a key to be stored in internal nodes; key is a part of \p value_type
120 typedef T value_type; ///< type of value to be stored in the binary tree
121 typedef Traits traits; ///< Traits template parameter
123 # ifdef CDS_DOXYGEN_INVOKED
124 typedef implementation_defined key_comparator ; ///< key compare functor based on opt::compare and opt::less option setter.
126 typedef typename maker::intrusive_traits::compare key_comparator;
128 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
129 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
130 typedef typename base_class::stat stat; ///< internal statistics type
131 typedef typename traits::key_extractor key_extractor; ///< key extracting functor
132 typedef typename traits::back_off back_off; ///< Back-off strategy
134 typedef typename traits::allocator allocator_type; ///< Allocator for leaf nodes
135 typedef typename base_class::node_allocator node_allocator; ///< Internal node allocator
136 typedef typename base_class::update_desc_allocator update_desc_allocator; ///< Update descriptor allocator
140 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
141 typedef typename base_class::value_type leaf_node;
142 typedef typename base_class::internal_node internal_node;
144 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
149 typedef cds::gc::guarded_ptr< gc, leaf_node, value_type, details::guarded_ptr_cast_set<leaf_node, value_type> > guarded_ptr;
152 /// Default constructor
163 The function creates a node with copy of \p val value
164 and then inserts the node created into the set.
166 The type \p Q should contain at least the complete key for the node.
167 The object of \ref value_type should be constructible from a value of type \p Q.
168 In trivial case, \p Q is equal to \ref value_type.
170 Returns \p true if \p val is inserted into the set, \p false otherwise.
172 template <typename Q>
173 bool insert( Q const& val )
175 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
176 if ( base_class::insert( *sp.get() )) {
185 The function allows to split creating of new item into two part:
186 - create item with key only
187 - insert new item into the set
188 - if inserting is success, calls \p f functor to initialize value-fields of \p val.
190 The functor signature is:
192 void func( value_type& val );
194 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
195 \p val no any other changes could be made on this set's item by concurrent threads.
196 The user-defined functor is called only if the inserting is success.
198 template <typename Q, typename Func>
199 bool insert( Q const& val, Func f )
201 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
202 if ( base_class::insert( *sp.get(), [&f]( leaf_node& val ) { f( val.m_Value ); } )) {
209 /// Ensures that the item exists in the set
211 The operation performs inserting or changing data with lock-free manner.
213 If the \p val key not found in the set, then the new item created from \p val
214 is inserted into the set. Otherwise, the functor \p func is called with the item found.
215 The functor \p Func should be a function with signature:
217 void func( bool bNew, value_type& item, const Q& val );
222 void operator()( bool bNew, value_type& item, const Q& val );
227 - \p bNew - \p true if the item has been inserted, \p false otherwise
228 - \p item - item of the set
229 - \p val - argument \p key passed into the \p ensure function
231 The functor may change non-key fields of the \p item; however, \p func must guarantee
232 that during changing no any other modifications could be made on this item by concurrent threads.
234 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
235 \p second is true if new item has been added or \p false if the item with \p key
236 already is in the set.
238 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
240 template <typename Q, typename Func>
241 std::pair<bool, bool> ensure( const Q& val, Func func )
243 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
244 std::pair<bool, bool> bRes = base_class::ensure( *sp,
245 [&func, &val](bool bNew, leaf_node& node, leaf_node&){ func( bNew, node.m_Value, val ); });
246 if ( bRes.first && bRes.second )
251 /// Inserts data of type \p value_type created in-place from \p args
253 Returns \p true if inserting successful, \p false otherwise.
255 template <typename... Args>
256 bool emplace( Args&&... args )
258 scoped_node_ptr sp( cxx_leaf_node_allocator().New( std::forward<Args>(args)... ));
259 if ( base_class::insert( *sp.get() )) {
266 /// Delete \p key from the set
267 /** \anchor cds_nonintrusive_EllenBinTreeSet_erase_val
269 The item comparator should be able to compare the type \p value_type
272 Return \p true if key is found and deleted, \p false otherwise
274 template <typename Q>
275 bool erase( Q const& key )
277 return base_class::erase( key );
280 /// Deletes the item from the set using \p pred predicate for searching
282 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_erase_val "erase(Q const&)"
283 but \p pred is used for key comparing.
284 \p Less functor has the interface like \p std::less.
285 \p Less must imply the same element order as the comparator used for building the set.
287 template <typename Q, typename Less>
288 bool erase_with( Q const& key, Less pred )
290 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
293 /// Delete \p key from the set
294 /** \anchor cds_nonintrusive_EllenBinTreeSet_erase_func
296 The function searches an item with key \p key, calls \p f functor
297 and deletes the item. If \p key is not found, the functor is not called.
299 The functor \p Func interface:
302 void operator()(value_type const& val);
306 Since the key of MichaelHashSet's \p value_type is not explicitly specified,
307 template parameter \p Q defines the key type searching in the list.
308 The list item comparator should be able to compare the type \p T of list item
311 Return \p true if key is found and deleted, \p false otherwise
313 template <typename Q, typename Func>
314 bool erase( Q const& key, Func f )
316 return base_class::erase( key, [&f]( leaf_node const& node) { f( node.m_Value ); } );
319 /// Deletes the item from the set using \p pred predicate for searching
321 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_erase_func "erase(Q const&, Func)"
322 but \p pred is used for key comparing.
323 \p Less functor has the interface like \p std::less.
324 \p Less must imply the same element order as the comparator used for building the set.
326 template <typename Q, typename Less, typename Func>
327 bool erase_with( Q const& key, Less pred, Func f )
329 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
330 [&f]( leaf_node const& node) { f( node.m_Value ); } );
333 /// Extracts an item with minimal key from the set
335 If the set is not empty, the function returns a guarded pointer to minimum value.
336 If the set is empty, the function returns an empty \p guarded_ptr.
338 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> minimum key.
339 It means that the function gets leftmost leaf of the tree and tries to unlink it.
340 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
341 So, the function returns the item with minimum key at the moment of tree traversing.
343 The guarded pointer prevents deallocation of returned item,
344 see \p cds::gc::guarded_ptr for explanation.
345 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
347 guarded_ptr extract_min()
350 base_class::extract_min_( gp.guard() );
354 /// Extracts an item with maximal key from the set
356 If the set is not empty, the function returns a guarded pointer to maximal value.
357 If the set is empty, the function returns an empty \p guarded_ptr.
359 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> maximal key.
360 It means that the function gets rightmost leaf of the tree and tries to unlink it.
361 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
362 So, the function returns the item with maximum key at the moment of tree traversing.
364 The guarded pointer prevents deallocation of returned item,
365 see \p cds::gc::guarded_ptr for explanation.
366 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
368 guarded_ptr extract_max()
371 base_class::extract_max_( gp.guard() );
375 /// Extracts an item from the tree
376 /** \anchor cds_nonintrusive_EllenBinTreeSet_extract
377 The function searches an item with key equal to \p key in the tree,
378 unlinks it, and returns an guarded pointer to it.
379 If the item is not found the function returns an empty \p guarded_ptr.
381 The guarded pointer prevents deallocation of returned item,
382 see \p cds::gc::guarded_ptr for explanation.
383 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
385 template <typename Q>
386 guarded_ptr extract( Q const& key )
389 base_class::extract_( gp.guard(), key );
393 /// Extracts an item from the set using \p pred for searching
395 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_extract "extract(Q const&)"
396 but \p pred is used for key compare.
397 \p Less has the interface like \p std::less.
398 \p pred must imply the same element order as the comparator used for building the set.
400 template <typename Q, typename Less>
401 guarded_ptr extract_with( Q const& key, Less pred )
404 base_class::extract_with_( gp.guard(), key,
405 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
409 /// Find the key \p key
411 @anchor cds_nonintrusive_EllenBinTreeSet_find_func
413 The function searches the item with key equal to \p key and calls the functor \p f for item found.
414 The interface of \p Func functor is:
417 void operator()( value_type& item, Q& key );
420 where \p item is the item found, \p key is the <tt>find</tt> function argument.
422 The functor may change non-key fields of \p item. Note that the functor is only guarantee
423 that \p item cannot be disposed during functor is executing.
424 The functor does not serialize simultaneous access to the set's \p item. If such access is
425 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
427 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
428 can modify both arguments.
430 Note the hash functor specified for class \p Traits template parameter
431 should accept a parameter of type \p Q that may be not the same as \p value_type.
433 The function returns \p true if \p key is found, \p false otherwise.
435 template <typename Q, typename Func>
436 bool find( Q& key, Func f )
438 return base_class::find( key, [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); });
441 template <typename Q, typename Func>
442 bool find( Q const& key, Func f )
444 return base_class::find( key, [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); } );
448 /// Finds the key \p key using \p pred predicate for searching
450 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_find_func "find(Q&, Func)"
451 but \p pred is used for key comparing.
452 \p Less functor has the interface like \p std::less.
453 \p Less must imply the same element order as the comparator used for building the set.
455 template <typename Q, typename Less, typename Func>
456 bool find_with( Q& key, Less pred, Func f )
458 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
459 [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); } );
462 template <typename Q, typename Less, typename Func>
463 bool find_with( Q const& key, Less pred, Func f )
465 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
466 [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); } );
470 /// Find the key \p key
471 /** @anchor cds_nonintrusive_EllenBinTreeSet_find_val
473 The function searches the item with key equal to \p key
474 and returns \p true if it is found, and \p false otherwise.
476 Note the hash functor specified for class \p Traits template parameter
477 should accept a parameter of type \p Q that may be not the same as \ref value_type.
479 template <typename Q>
480 bool find( Q const & key )
482 return base_class::find( key );
485 /// Finds the key \p key using \p pred predicate for searching
487 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_find_val "find(Q const&)"
488 but \p pred is used for key comparing.
489 \p Less functor has the interface like \p std::less.
490 \p Less must imply the same element order as the comparator used for building the set.
492 template <typename Q, typename Less>
493 bool find_with( Q const& key, Less pred )
495 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
498 /// Finds \p key and returns the item found
499 /** @anchor cds_nonintrusive_EllenBinTreeSet_get
500 The function searches the item with key equal to \p key and returns the item found as an guarded pointer.
501 The function returns \p true if \p key is found, \p false otherwise.
503 The guarded pointer prevents deallocation of returned item,
504 see \p cds::gc::guarded_ptr for explanation.
505 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
507 template <typename Q>
508 guarded_ptr get( Q const& key )
511 base_class::get_( gp.guard(), key );
515 /// Finds \p key with predicate \p pred and returns the item found
517 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_get "get(Q const&)"
518 but \p pred is used for key comparing.
519 \p Less functor has the interface like \p std::less.
520 \p pred must imply the same element order as the comparator used for building the set.
522 template <typename Q, typename Less>
523 guarded_ptr get_with( Q const& key, Less pred )
526 base_class::get_with_( gp.guard(), key,
527 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >() );
531 /// Clears the set (not atomic)
533 The function unlink all items from the tree.
534 The function is not atomic, thus, in multi-threaded environment with parallel insertions
538 assert( set.empty() );
540 the assertion could be raised.
542 For each leaf the \ref disposer will be called after unlinking.
549 /// Checks if the set is empty
552 return base_class::empty();
555 /// Returns item count in the set
557 Only leaf nodes containing user data are counted.
559 The value returned depends on item counter type provided by \p Traits template parameter.
560 If it is \p atomicity::empty_item_counter this function always returns 0.
562 The function is not suitable for checking the tree emptiness, use \p empty()
563 member function for this purpose.
567 return base_class::size();
570 /// Returns const reference to internal statistics
571 stat const& statistics() const
573 return base_class::statistics();
576 /// Checks internal consistency (not atomic, not thread-safe)
578 The debugging function to check internal consistency of the tree.
580 bool check_consistency() const
582 return base_class::check_consistency();
586 }} // namespace cds::container
588 #endif // #ifndef __CDS_CONTAINER_IMPL_ELLEN_BINTREE_SET_H