3 #ifndef CDSLIB_CONTAINER_IMPL_ELLEN_BINTREE_SET_H
4 #define CDSLIB_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
139 typedef cds::container::ellen_bintree::implementation_tag implementation_tag;
144 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
145 typedef typename base_class::value_type leaf_node;
146 typedef typename base_class::internal_node internal_node;
148 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
153 typedef typename gc::template guarded_ptr< leaf_node, value_type, details::guarded_ptr_cast_set<leaf_node, value_type> > guarded_ptr;
156 /// Default constructor
167 The function creates a node with copy of \p val value
168 and then inserts the node created into the set.
170 The type \p Q should contain at least the complete key for the node.
171 The object of \ref value_type should be constructible from a value of type \p Q.
172 In trivial case, \p Q is equal to \ref value_type.
174 Returns \p true if \p val is inserted into the set, \p false otherwise.
176 template <typename Q>
177 bool insert( Q const& val )
179 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
180 if ( base_class::insert( *sp.get() )) {
189 The function allows to split creating of new item into two part:
190 - create item with key only
191 - insert new item into the set
192 - if inserting is success, calls \p f functor to initialize value-fields of \p val.
194 The functor signature is:
196 void func( value_type& val );
198 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
199 \p val no any other changes could be made on this set's item by concurrent threads.
200 The user-defined functor is called only if the inserting is success.
202 template <typename Q, typename Func>
203 bool insert( Q const& val, Func f )
205 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
206 if ( base_class::insert( *sp.get(), [&f]( leaf_node& val ) { f( val.m_Value ); } )) {
213 /// Ensures that the item exists in the set
215 The operation performs inserting or changing data with lock-free manner.
217 If the \p val key not found in the set, then the new item created from \p val
218 is inserted into the set. Otherwise, the functor \p func is called with the item found.
219 The functor \p Func should be a function with signature:
221 void func( bool bNew, value_type& item, const Q& val );
226 void operator()( bool bNew, value_type& item, const Q& val );
231 - \p bNew - \p true if the item has been inserted, \p false otherwise
232 - \p item - item of the set
233 - \p val - argument \p key passed into the \p ensure function
235 The functor may change non-key fields of the \p item; however, \p func must guarantee
236 that during changing no any other modifications could be made on this item by concurrent threads.
238 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
239 \p second is true if new item has been added or \p false if the item with \p key
240 already is in the set.
242 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
244 template <typename Q, typename Func>
245 std::pair<bool, bool> ensure( const Q& val, Func func )
247 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
248 std::pair<bool, bool> bRes = base_class::ensure( *sp,
249 [&func, &val](bool bNew, leaf_node& node, leaf_node&){ func( bNew, node.m_Value, val ); });
250 if ( bRes.first && bRes.second )
255 /// Inserts data of type \p value_type created in-place from \p args
257 Returns \p true if inserting successful, \p false otherwise.
259 template <typename... Args>
260 bool emplace( Args&&... args )
262 scoped_node_ptr sp( cxx_leaf_node_allocator().New( std::forward<Args>(args)... ));
263 if ( base_class::insert( *sp.get() )) {
270 /// Delete \p key from the set
271 /** \anchor cds_nonintrusive_EllenBinTreeSet_erase_val
273 The item comparator should be able to compare the type \p value_type
276 Return \p true if key is found and deleted, \p false otherwise
278 template <typename Q>
279 bool erase( Q const& key )
281 return base_class::erase( key );
284 /// Deletes the item from the set using \p pred predicate for searching
286 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_erase_val "erase(Q const&)"
287 but \p pred is used for key comparing.
288 \p Less functor has the interface like \p std::less.
289 \p Less must imply the same element order as the comparator used for building the set.
291 template <typename Q, typename Less>
292 bool erase_with( Q const& key, Less pred )
295 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
298 /// Delete \p key from the set
299 /** \anchor cds_nonintrusive_EllenBinTreeSet_erase_func
301 The function searches an item with key \p key, calls \p f functor
302 and deletes the item. If \p key is not found, the functor is not called.
304 The functor \p Func interface:
307 void operator()(value_type const& val);
311 Since the key of MichaelHashSet's \p value_type is not explicitly specified,
312 template parameter \p Q defines the key type searching in the list.
313 The list item comparator should be able to compare the type \p T of list item
316 Return \p true if key is found and deleted, \p false otherwise
318 template <typename Q, typename Func>
319 bool erase( Q const& key, Func f )
321 return base_class::erase( key, [&f]( leaf_node const& node) { f( node.m_Value ); } );
324 /// Deletes the item from the set using \p pred predicate for searching
326 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_erase_func "erase(Q const&, Func)"
327 but \p pred is used for key comparing.
328 \p Less functor has the interface like \p std::less.
329 \p Less must imply the same element order as the comparator used for building the set.
331 template <typename Q, typename Less, typename Func>
332 bool erase_with( Q const& key, Less pred, Func f )
335 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
336 [&f]( leaf_node const& node) { f( node.m_Value ); } );
339 /// Extracts an item with minimal key from the set
341 If the set is not empty, the function returns a guarded pointer to minimum value.
342 If the set is empty, the function returns an empty \p guarded_ptr.
344 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> minimum key.
345 It means that the function gets leftmost leaf of the tree and tries to unlink it.
346 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
347 So, the function returns the item with minimum key at the moment of tree traversing.
349 The guarded pointer prevents deallocation of returned item,
350 see \p cds::gc::guarded_ptr for explanation.
351 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
353 guarded_ptr extract_min()
356 base_class::extract_min_( gp.guard() );
360 /// Extracts an item with maximal key from the set
362 If the set is not empty, the function returns a guarded pointer to maximal value.
363 If the set is empty, the function returns an empty \p guarded_ptr.
365 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> maximal key.
366 It means that the function gets rightmost leaf of the tree and tries to unlink it.
367 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
368 So, the function returns the item with maximum key at the moment of tree traversing.
370 The guarded pointer prevents deallocation of returned item,
371 see \p cds::gc::guarded_ptr for explanation.
372 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
374 guarded_ptr extract_max()
377 base_class::extract_max_( gp.guard() );
381 /// Extracts an item from the tree
382 /** \anchor cds_nonintrusive_EllenBinTreeSet_extract
383 The function searches an item with key equal to \p key in the tree,
384 unlinks it, and returns an guarded pointer to it.
385 If the item is not found the function returns an empty \p guarded_ptr.
387 The guarded pointer prevents deallocation of returned item,
388 see \p cds::gc::guarded_ptr for explanation.
389 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
391 template <typename Q>
392 guarded_ptr extract( Q const& key )
395 base_class::extract_( gp.guard(), key );
399 /// Extracts an item from the set using \p pred for searching
401 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_extract "extract(Q const&)"
402 but \p pred is used for key compare.
403 \p Less has the interface like \p std::less.
404 \p pred must imply the same element order as the comparator used for building the set.
406 template <typename Q, typename Less>
407 guarded_ptr extract_with( Q const& key, Less pred )
411 base_class::extract_with_( gp.guard(), key,
412 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
416 /// Find the key \p key
418 @anchor cds_nonintrusive_EllenBinTreeSet_find_func
420 The function searches the item with key equal to \p key and calls the functor \p f for item found.
421 The interface of \p Func functor is:
424 void operator()( value_type& item, Q& key );
427 where \p item is the item found, \p key is the <tt>find</tt> function argument.
429 The functor may change non-key fields of \p item. Note that the functor is only guarantee
430 that \p item cannot be disposed during functor is executing.
431 The functor does not serialize simultaneous access to the set's \p item. If such access is
432 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
434 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
435 can modify both arguments.
437 Note the hash functor specified for class \p Traits template parameter
438 should accept a parameter of type \p Q that may be not the same as \p value_type.
440 The function returns \p true if \p key is found, \p false otherwise.
442 template <typename Q, typename Func>
443 bool find( Q& key, Func f )
445 return base_class::find( key, [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); });
448 template <typename Q, typename Func>
449 bool find( Q const& key, Func f )
451 return base_class::find( key, [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); } );
455 /// Finds the key \p key using \p pred predicate for searching
457 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_find_func "find(Q&, Func)"
458 but \p pred is used for key comparing.
459 \p Less functor has the interface like \p std::less.
460 \p Less must imply the same element order as the comparator used for building the set.
462 template <typename Q, typename Less, typename Func>
463 bool find_with( Q& key, Less pred, Func f )
466 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
467 [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); } );
470 template <typename Q, typename Less, typename Func>
471 bool find_with( Q const& key, Less pred, Func f )
474 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
475 [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); } );
479 /// Find the key \p key
480 /** @anchor cds_nonintrusive_EllenBinTreeSet_find_val
482 The function searches the item with key equal to \p key
483 and returns \p true if it is found, and \p false otherwise.
485 Note the hash functor specified for class \p Traits template parameter
486 should accept a parameter of type \p Q that may be not the same as \ref value_type.
488 template <typename Q>
489 bool find( Q const & key )
491 return base_class::find( key );
494 /// Finds the key \p key using \p pred predicate for searching
496 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_find_val "find(Q const&)"
497 but \p pred is used for key comparing.
498 \p Less functor has the interface like \p std::less.
499 \p Less must imply the same element order as the comparator used for building the set.
501 template <typename Q, typename Less>
502 bool find_with( Q const& key, Less pred )
505 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
508 /// Finds \p key and returns the item found
509 /** @anchor cds_nonintrusive_EllenBinTreeSet_get
510 The function searches the item with key equal to \p key and returns the item found as an guarded pointer.
511 The function returns \p true if \p key is found, \p false otherwise.
513 The guarded pointer prevents deallocation of returned item,
514 see \p cds::gc::guarded_ptr for explanation.
515 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
517 template <typename Q>
518 guarded_ptr get( Q const& key )
521 base_class::get_( gp.guard(), key );
525 /// Finds \p key with predicate \p pred and returns the item found
527 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_get "get(Q const&)"
528 but \p pred is used for key comparing.
529 \p Less functor has the interface like \p std::less.
530 \p pred must imply the same element order as the comparator used for building the set.
532 template <typename Q, typename Less>
533 guarded_ptr get_with( Q const& key, Less pred )
537 base_class::get_with_( gp.guard(), key,
538 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >() );
542 /// Clears the set (not atomic)
544 The function unlink all items from the tree.
545 The function is not atomic, thus, in multi-threaded environment with parallel insertions
549 assert( set.empty() );
551 the assertion could be raised.
553 For each leaf the \ref disposer will be called after unlinking.
560 /// Checks if the set is empty
563 return base_class::empty();
566 /// Returns item count in the set
568 Only leaf nodes containing user data are counted.
570 The value returned depends on item counter type provided by \p Traits template parameter.
571 If it is \p atomicity::empty_item_counter this function always returns 0.
573 The function is not suitable for checking the tree emptiness, use \p empty()
574 member function for this purpose.
578 return base_class::size();
581 /// Returns const reference to internal statistics
582 stat const& statistics() const
584 return base_class::statistics();
587 /// Checks internal consistency (not atomic, not thread-safe)
589 The debugging function to check internal consistency of the tree.
591 bool check_consistency() const
593 return base_class::check_consistency();
597 }} // namespace cds::container
599 #endif // #ifndef CDSLIB_CONTAINER_IMPL_ELLEN_BINTREE_SET_H