3 #ifndef __CDS_CONTAINER_ELLEN_BINTREE_SET_RCU_H
4 #define __CDS_CONTAINER_ELLEN_BINTREE_SET_RCU_H
6 #include <cds/container/details/ellen_bintree_base.h>
7 #include <cds/intrusive/ellen_bintree_rcu.h>
9 namespace cds { namespace container {
11 /// Set based on Ellen's et al binary search tree (RCU specialization)
12 /** @ingroup cds_nonintrusive_set
13 @ingroup cds_nonintrusive_tree
14 @anchor cds_container_EllenBinTreeSet_rcu
17 - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"
19 %EllenBinTreeSet is an unbalanced leaf-oriented binary search tree that implements the <i>set</i>
20 abstract data type. Nodes maintains child pointers but not parent pointers.
21 Every internal node has exactly two children, and all data of type \p T currently in
22 the tree are stored in the leaves. Internal nodes of the tree are used to direct \p find
23 operation along the path to the correct leaf. The keys (of \p Key type) stored in internal nodes
24 may or may not be in the set. \p Key type is a subset of \p T type.
25 There should be exactly defined a key extracting functor for converting object of type \p T to
26 object of type \p Key.
28 Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeSet can act as
29 a <i>priority queue</i>. In this case you should provide unique compound key, for example,
30 the priority value plus some uniformly distributed random value.
32 @warning Recall the tree is <b>unbalanced</b>. The complexity of operations is <tt>O(log N)</tt>
33 for uniformly distributed random keys, but in worst case the complexity is <tt>O(N)</tt>.
35 @note In the current implementation we do not use helping technique described in original paper.
36 So, the current implementation is near to fine-grained lock-based tree.
37 Helping will be implemented in future release
39 <b>Template arguments</b> :
40 - \p RCU - one of \ref cds_urcu_gc "RCU type"
41 - \p Key - key type, a subset of \p T
42 - \p T - type to be stored in tree's leaf nodes.
43 - \p Traits - type traits. See ellen_bintree::type_traits for explanation.
45 It is possible to declare option-based tree with ellen_bintree::make_set_traits metafunction
46 instead of \p Traits template argument.
47 Template argument list \p Options of ellen_bintree::make_set_traits metafunction are:
48 - ellen_bintree::key_extractor - key extracting functor, mandatory option. The functor has the following prototype:
50 struct key_extractor {
51 void operator ()( Key& dest, T const& src );
54 It should initialize \p dest key from \p src data. The functor is used to initialize internal nodes.
55 - opt::compare - key compare functor. No default functor is provided.
56 If the option is not specified, \p %opt::less is used.
57 - opt::less - specifies binary predicate used for key compare. At least \p %opt::compare or \p %opt::less should be defined.
58 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
59 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
60 or opt::v::sequential_consistent (sequentially consisnent memory model).
61 - opt::allocator - the allocator used for \ref ellen_bintree::node "leaf nodes" which contains data.
62 Default is \ref CDS_DEFAULT_ALLOCATOR.
63 - opt::node_allocator - the allocator used for internal nodes. Default is \ref CDS_DEFAULT_ALLOCATOR.
64 - ellen_bintree::update_desc_allocator - an allocator of \ref ellen_bintree::update_desc "update descriptors",
65 default is \ref CDS_DEFAULT_ALLOCATOR.
66 Note that update descriptor is helping data structure with short lifetime and it is good candidate for pooling.
67 The number of simultaneously existing descriptors is a relatively small number limited the number of threads
68 working with the tree and RCU buffer size.
69 Therefore, a bounded lock-free container like \p cds::container::VyukovMPMCCycleQueue is good choice for the free-list
70 of update descriptors, see cds::memory::vyukov_queue_pool free-list implementation.
71 Also notice that size of update descriptor is not dependent on the type of data
72 stored in the tree so single free-list object can be used for several EllenBinTree-based object.
73 - opt::stat - internal statistics. Available types: ellen_bintree::stat, ellen_bintree::empty_stat (the default)
74 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
76 @note Before including <tt><cds/container/ellen_bintree_set_rcu.h></tt> you should include appropriate RCU header file,
77 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
79 @anchor cds_container_EllenBinTreeSet_rcu_less
80 <b>Predicate requirements</b>
82 opt::less, opt::compare and other predicates using with member fuctions should accept at least parameters
83 of type \p T and \p Key in any combination.
84 For example, for \p Foo struct with \p std::string key field the appropiate \p less functor is:
93 bool operator()( Foo const& v1, Foo const& v2 ) const
94 { return v1.m_strKey < v2.m_strKey ; }
96 bool operator()( Foo const& v, std::string const& s ) const
97 { return v.m_strKey < s ; }
99 bool operator()( std::string const& s, Foo const& v ) const
100 { return s < v.m_strKey ; }
102 // Support comparing std::string and char const *
103 bool operator()( std::string const& s, char const * p ) const
104 { return s.compare(p) < 0 ; }
106 bool operator()( Foo const& v, char const * p ) const
107 { return v.m_strKey.compare(p) < 0 ; }
109 bool operator()( char const * p, std::string const& s ) const
110 { return s.compare(p) > 0; }
112 bool operator()( char const * p, Foo const& v ) const
113 { return v.m_strKey.compare(p) > 0; }
122 #ifdef CDS_DOXYGEN_INVOKED
123 class Traits = ellen_bintree::type_traits
128 class EllenBinTreeSet< cds::urcu::gc<RCU>, Key, T, Traits >
129 #ifdef CDS_DOXYGEN_INVOKED
130 : public cds::intrusive::EllenBinTree< cds::urcu::gc<RCU>, Key, T, Traits >
132 : public ellen_bintree::details::make_ellen_bintree_set< cds::urcu::gc<RCU>, Key, T, Traits >::type
136 typedef ellen_bintree::details::make_ellen_bintree_set< cds::urcu::gc<RCU>, Key, T, Traits > maker;
137 typedef typename maker::type base_class;
141 typedef cds::urcu::gc<RCU> gc ; ///< RCU Garbage collector
142 typedef Key key_type ; ///< type of a key stored in internal nodes; key is a part of \p value_type
143 typedef T value_type ; ///< type of value stored in the binary tree
144 typedef Traits options ; ///< Traits template parameter
146 # ifdef CDS_DOXYGEN_INVOKED
147 typedef implementation_defined key_comparator ; ///< key compare functor based on opt::compare and opt::less option setter.
149 typedef typename maker::intrusive_type_traits::compare key_comparator;
151 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
152 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
153 typedef typename base_class::stat stat ; ///< internal statistics type
154 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< Deadlock checking policy
155 typedef typename options::key_extractor key_extractor ; ///< key extracting functor
157 typedef typename options::allocator allocator_type ; ///< Allocator for leaf nodes
158 typedef typename base_class::node_allocator node_allocator ; ///< Internal node allocator
159 typedef typename base_class::update_desc_allocator update_desc_allocator ; ///< Update descriptor allocator
161 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
165 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
166 typedef typename base_class::value_type leaf_node;
167 typedef typename base_class::internal_node internal_node;
168 typedef std::unique_ptr< leaf_node, typename maker::intrusive_type_traits::disposer > scoped_node_ptr;
172 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
174 /// pointer to extracted node
175 typedef cds::urcu::exempt_ptr< gc, leaf_node, value_type, typename maker::intrusive_type_traits::disposer,
176 cds::urcu::details::conventional_exempt_member_cast<leaf_node, value_type>
180 /// Default constructor
191 The function creates a node with copy of \p val value
192 and then inserts the node created into the set.
194 The type \p Q should contain at least the complete key for the node.
195 The object of \ref value_type should be constructible from a value of type \p Q.
196 In trivial case, \p Q is equal to \ref value_type.
198 RCU \p synchronize method can be called. RCU should not be locked.
200 Returns \p true if \p val is inserted into the set, \p false otherwise.
202 template <typename Q>
203 bool insert( Q const& val )
205 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
206 if ( base_class::insert( *sp.get() )) {
215 The function allows to split creating of new item into two part:
216 - create item with key only
217 - insert new item into the set
218 - if inserting is success, calls \p f functor to initialize value-fields of \p val.
220 The functor signature is:
222 void func( value_type& val );
224 where \p val is the item inserted. User-defined functor \p f should guarantee that during changing
225 \p val no any other changes could be made on this set's item by concurrent threads.
226 The user-defined functor is called only if the inserting is success.
228 RCU \p synchronize method can be called. RCU should not be locked.
230 template <typename Q, typename Func>
231 bool insert( Q const& val, Func f )
233 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
234 if ( base_class::insert( *sp.get(), [&f]( leaf_node& val ) { f( val.m_Value ); } )) {
241 /// Ensures that the item exists in the set
243 The operation performs inserting or changing data with lock-free manner.
245 If the \p val key not found in the set, then the new item created from \p val
246 is inserted into the set. Otherwise, the functor \p func is called with the item found.
247 The functor \p Func should be a function with signature:
249 void func( bool bNew, value_type& item, const Q& val );
254 void operator()( bool bNew, value_type& item, const Q& val );
259 - \p bNew - \p true if the item has been inserted, \p false otherwise
260 - \p item - item of the set
261 - \p val - argument \p key passed into the \p ensure function
263 The functor may change non-key fields of the \p item; however, \p func must guarantee
264 that during changing no any other modifications could be made on this item by concurrent threads.
266 RCU \p synchronize method can be called. RCU should not be locked.
268 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
269 \p second is true if new item has been added or \p false if the item with \p key
270 already is in the set.
272 template <typename Q, typename Func>
273 std::pair<bool, bool> ensure( const Q& val, Func func )
275 scoped_node_ptr sp( cxx_leaf_node_allocator().New( val ));
276 std::pair<bool, bool> bRes = base_class::ensure( *sp,
277 [&func, &val](bool bNew, leaf_node& node, leaf_node&){ func( bNew, node.m_Value, val ); });
278 if ( bRes.first && bRes.second )
283 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
285 Returns \p true if inserting successful, \p false otherwise.
287 RCU \p synchronize method can be called. RCU should not be locked.
289 template <typename... Args>
290 bool emplace( Args&&... args )
292 scoped_node_ptr sp( cxx_leaf_node_allocator().New( std::forward<Args>(args)... ));
293 if ( base_class::insert( *sp.get() )) {
300 /// Delete \p key from the set
301 /** \anchor cds_nonintrusive_EllenBinTreeSet_rcu_erase_val
303 The item comparator should be able to compare the type \p value_type
306 RCU \p synchronize method can be called. RCU should not be locked.
308 Return \p true if key is found and deleted, \p false otherwise
310 template <typename Q>
311 bool erase( Q const& key )
313 return base_class::erase( key );
316 /// Deletes the item from the set using \p pred predicate for searching
318 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_erase_val "erase(Q const&)"
319 but \p pred is used for key comparing.
320 \p Less functor has the interface like \p std::less.
321 \p Less must imply the same element order as the comparator used for building the set.
323 template <typename Q, typename Less>
324 bool erase_with( Q const& key, Less pred )
326 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
329 /// Delete \p key from the set
330 /** \anchor cds_nonintrusive_EllenBinTreeSet_rcu_erase_func
332 The function searches an item with key \p key, calls \p f functor
333 and deletes the item. If \p key is not found, the functor is not called.
335 The functor \p Func interface:
338 void operator()(value_type const& val);
342 Since the key of MichaelHashSet's \p value_type is not explicitly specified,
343 template parameter \p Q defines the key type searching in the list.
344 The list item comparator should be able to compare the type \p T of list item
347 RCU \p synchronize method can be called. RCU should not be locked.
349 Return \p true if key is found and deleted, \p false otherwise
353 template <typename Q, typename Func>
354 bool erase( Q const& key, Func f )
356 return base_class::erase( key, [&f]( leaf_node const& node) { f( node.m_Value ); } );
359 /// Deletes the item from the set using \p pred predicate for searching
361 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_erase_func "erase(Q const&, Func)"
362 but \p pred is used for key comparing.
363 \p Less functor has the interface like \p std::less.
364 \p Less must imply the same element order as the comparator used for building the set.
366 template <typename Q, typename Less, typename Func>
367 bool erase_with( Q const& key, Less pred, Func f )
369 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
370 [&f]( leaf_node const& node) { f( node.m_Value ); } );
373 /// Extracts an item with minimal key from the set
375 If the set is not empty, the function returns \p true, \p result contains a pointer to value.
376 If the set is empty, the function returns \p false, \p result is left unchanged.
378 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> minimum key.
379 It means that the function gets leftmost leaf of the tree and tries to unlink it.
380 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
381 So, the function returns the item with minimum key at the moment of tree traversing.
383 RCU \p synchronize method can be called. RCU should NOT be locked.
384 The function does not free the item.
385 The deallocator will be implicitly invoked when \p result object is destroyed or when
386 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
387 @note Before reusing \p result object you should call its \p release() method.
389 bool extract_min( exempt_ptr& result )
391 return base_class::extract_min_( result );
394 /// Extracts an item with maximal key from the set
396 If the set is not empty, the function returns \p true, \p result contains a pointer to extracted item.
397 If the set is empty, the function returns \p false, \p result is left unchanged.
399 @note Due the concurrent nature of the set, the function extracts <i>nearly</i> maximal key.
400 It means that the function gets rightmost leaf of the tree and tries to unlink it.
401 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
402 So, the function returns the item with maximum key at the moment of tree traversing.
404 RCU \p synchronize method can be called. RCU should NOT be locked.
405 The function does not free the item.
406 The deallocator will be implicitly invoked when \p result object is destroyed or when
407 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
408 @note Before reusing \p result object you should call its \p release() method.
410 bool extract_max( exempt_ptr& result )
412 return base_class::extract_max_( result );
415 /// Extracts an item from the set
416 /** \anchor cds_nonintrusive_EllenBinTreeSet_rcu_extract
417 The function searches an item with key equal to \p key in the tree,
418 unlinks it, and returns pointer to an item found in \p result parameter.
419 If \p key is not found the function returns \p false.
421 RCU \p synchronize method can be called. RCU should NOT be locked.
422 The function does not destroy the item found.
423 The dealloctor will be implicitly invoked when \p result object is destroyed or when
424 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
425 @note Before reusing \p result object you should call its \p release() method.
427 template <typename Q>
428 bool extract( exempt_ptr& result, Q const& key )
430 return base_class::extract_( result, key, typename base_class::node_compare());
433 /// Extracts an item from the set using \p pred for searching
435 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_extract "extract(exempt_ptr&, Q const&)"
436 but \p pred is used for key compare.
437 \p Less has the interface like \p std::less and should meet \ref cds_container_EllenBinTreeSet_rcu_less
438 "predicate requirements".
439 \p pred must imply the same element order as the comparator used for building the set.
441 template <typename Q, typename Less>
442 bool extract_with( exempt_ptr& result, Q const& val, Less pred )
444 return base_class::extract_with_( result, val,
445 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >() );
448 /// Find the key \p val
450 @anchor cds_nonintrusive_EllenBinTreeSet_rcu_find_func
452 The function searches the item with key equal to \p val and calls the functor \p f for item found.
453 The interface of \p Func functor is:
456 void operator()( value_type& item, Q& val );
459 where \p item is the item found, \p val is the <tt>find</tt> function argument.
461 The functor may change non-key fields of \p item. Note that the functor is only guarantee
462 that \p item cannot be disposed during functor is executing.
463 The functor does not serialize simultaneous access to the set's \p item. If such access is
464 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
466 The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor
467 can modify both arguments.
469 Note the hash functor specified for class \p Traits template parameter
470 should accept a parameter of type \p Q that may be not the same as \p value_type.
472 The function applies RCU lock internally.
474 The function returns \p true if \p val is found, \p false otherwise.
476 template <typename Q, typename Func>
477 bool find( Q& val, Func f ) const
479 return base_class::find( val, [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); });
482 /// Finds the key \p val using \p pred predicate for searching
484 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_find_func "find(Q&, Func)"
485 but \p pred is used for key comparing.
486 \p Less functor has the interface like \p std::less.
487 \p Less must imply the same element order as the comparator used for building the set.
489 template <typename Q, typename Less, typename Func>
490 bool find_with( Q& val, Less pred, Func f ) const
492 return base_class::find_with( val, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
493 [&f]( leaf_node& node, Q& v ) { f( node.m_Value, v ); } );
496 /// Find the key \p val
497 /** @anchor cds_nonintrusive_EllenBinTreeSet_rcu_find_cfunc
499 The function searches the item with key equal to \p val and calls the functor \p f for item found.
500 The interface of \p Func functor is:
503 void operator()( value_type& item, Q const& val );
506 where \p item is the item found, \p val is the <tt>find</tt> function argument.
508 The functor may change non-key fields of \p item. Note that the functor is only guarantee
509 that \p item cannot be disposed during functor is executing.
510 The functor does not serialize simultaneous access to the set's \p item. If such access is
511 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
513 Note the hash functor specified for class \p Traits template parameter
514 should accept a parameter of type \p Q that may be not the same as \p value_type.
516 The function applies RCU lock internally.
518 The function returns \p true if \p val is found, \p false otherwise.
520 template <typename Q, typename Func>
521 bool find( Q const& val, Func f ) const
523 return base_class::find( val, [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); });
526 /// Finds the key \p val using \p pred predicate for searching
528 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_find_cfunc "find(Q const&, Func)"
529 but \p pred is used for key comparing.
530 \p Less functor has the interface like \p std::less.
531 \p Less must imply the same element order as the comparator used for building the set.
533 template <typename Q, typename Less, typename Func>
534 bool find_with( Q const& val, Less pred, Func f ) const
536 return base_class::find_with( val, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >(),
537 [&f]( leaf_node& node, Q const& v ) { f( node.m_Value, v ); } );
540 /// Find the key \p val
541 /** @anchor cds_nonintrusive_EllenBinTreeSet_rcu_find_val
543 The function searches the item with key equal to \p val
544 and returns \p true if it is found, and \p false otherwise.
546 Note the hash functor specified for class \p Traits template parameter
547 should accept a parameter of type \p Q that may be not the same as \ref value_type.
549 The function applies RCU lock internally.
551 template <typename Q>
552 bool find( Q const & val ) const
554 return base_class::find( val );
557 /// Finds the key \p val using \p pred predicate for searching
559 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_find_val "find(Q const&)"
560 but \p pred is used for key comparing.
561 \p Less functor has the interface like \p std::less.
562 \p Less must imply the same element order as the comparator used for building the set.
564 template <typename Q, typename Less>
565 bool find_with( Q const& val, Less pred ) const
567 return base_class::find_with( val, cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
570 /// Finds \p key and return the item found
571 /** \anchor cds_nonintrusive_EllenBinTreeSet_rcu_get
572 The function searches the item with key equal to \p key and returns the pointer to item found.
573 If \p key is not found it returns \p nullptr.
575 RCU should be locked before call the function.
576 Returned pointer is valid while RCU is locked.
578 template <typename Q>
579 value_type * get( Q const& key ) const
581 leaf_node * pNode = base_class::get( key );
582 return pNode ? &pNode->m_Value : nullptr;
585 /// Finds \p key with \p pred predicate and return the item found
587 The function is an analog of \ref cds_nonintrusive_EllenBinTreeSet_rcu_get "get(Q const&)"
588 but \p pred is used for comparing the keys.
590 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type
591 and \p Q in any order.
592 \p pred must imply the same element order as the comparator used for building the set.
594 template <typename Q, typename Less>
595 value_type * get_with( Q const& key, Less pred ) const
597 leaf_node * pNode = base_class::get_with( key,
598 cds::details::predicate_wrapper< leaf_node, Less, typename maker::value_accessor >());
599 return pNode ? &pNode->m_Value : nullptr;
602 /// Clears the set (non-atomic)
604 The function unlink all items from the tree.
605 The function is not atomic, thus, in multi-threaded environment with parallel insertions
609 assert( set.empty() );
611 the assertion could be raised.
613 For each leaf the \ref disposer will be called after unlinking.
615 RCU \p synchronize method can be called. RCU should not be locked.
622 /// Checks if the set is empty
625 return base_class::empty();
628 /// Returns item count in the set
630 Only leaf nodes containing user data are counted.
632 The value returned depends on item counter type provided by \p Traits template parameter.
633 If it is atomicity::empty_item_counter this function always returns 0.
634 Therefore, the function is not suitable for checking the tree emptiness, use \ref empty
635 member function for this purpose.
639 return base_class::size();
642 /// Returns const reference to internal statistics
643 stat const& statistics() const
645 return base_class::statistics();
648 /// Checks internal consistency (not atomic, not thread-safe)
650 The debugging function to check internal consistency of the tree.
652 bool check_consistency() const
654 return base_class::check_consistency();
659 }} // namespace cds::container
661 #endif // #ifndef __CDS_CONTAINER_ELLEN_BINTREE_SET_RCU_H