3 #ifndef __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H
4 #define __CDS_CONTAINER_ELLEN_BINTREE_MAP_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 /// Map based on Ellen's et al binary search tree (RCU specialization)
12 /** @ingroup cds_nonintrusive_map
13 @ingroup cds_nonintrusive_tree
14 @anchor cds_container_EllenBinTreeMap_rcu
17 - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"
19 %EllenBinTreeMap is an unbalanced leaf-oriented binary search tree that implements the <i>map</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 <tt>std::pair<Key const, T></tt>
22 currently in 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 map.
25 Unlike \ref cds_container_EllenBinTreeSet_rcu "EllenBinTreeSet" keys are not a part of \p T type.
26 The map can be represented as a set containing <tt>std::pair< Key const, T> </tt> values.
28 Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeMap 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"
42 - \p T - value 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_map_traits metafunction
46 instead of \p Traits template argument.
47 Template argument list \p Options of ellen_bintree::make_map_traits metafunction are:
48 - opt::compare - key compare functor. No default functor is provided.
49 If the option is not specified, \p %opt::less is used.
50 - opt::less - specifies binary predicate used for key compare. At least \p %opt::compare or \p %opt::less should be defined.
51 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
52 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
53 or opt::v::sequential_consistent (sequentially consisnent memory model).
54 - opt::allocator - the allocator used for \ref ellen_bintree::map_node "leaf nodes" which contains data.
55 Default is \ref CDS_DEFAULT_ALLOCATOR.
56 - opt::node_allocator - the allocator used for \ref ellen_bintree::internal_node "internal nodes".
57 Default is \ref CDS_DEFAULT_ALLOCATOR.
58 - ellen_bintree::update_desc_allocator - an allocator of \ref ellen_bintree::update_desc "update descriptors",
59 default is \ref CDS_DEFAULT_ALLOCATOR.
60 Note that update descriptor is helping data structure with short lifetime and it is good candidate for pooling.
61 The number of simultaneously existing descriptors is a relatively small number limited the number of threads
62 working with the tree and RCU buffer size.
63 Therefore, a bounded lock-free container like \p cds::container::VyukovMPMCCycleQueue is good choice for the free-list
64 of update descriptors, see cds::memory::vyukov_queue_pool free-list implementation.
65 Also notice that size of update descriptor is not dependent on the type of data
66 stored in the tree so single free-list object can be used for several EllenBinTree-based object.
67 - opt::stat - internal statistics. Available types: ellen_bintree::stat, ellen_bintree::empty_stat (the default)
68 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
69 - opt::copy_policy - key copy policy defines a functor to copy leaf node's key to internal node.
70 By default, assignment operator is used.
71 The copy functor interface is:
74 void operator()( Key& dest, Key const& src );
78 @note Before including <tt><cds/container/ellen_bintree_map_rcu.h></tt> you should include appropriate RCU header file,
79 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
85 #ifdef CDS_DOXYGEN_INVOKED
86 class Traits = ellen_bintree::type_traits
91 class EllenBinTreeMap< cds::urcu::gc<RCU>, Key, T, Traits >
92 #ifdef CDS_DOXYGEN_INVOKED
93 : public cds::intrusive::EllenBinTree< cds::urcu::gc<RCU>, Key, T, Traits >
95 : public ellen_bintree::details::make_ellen_bintree_map< cds::urcu::gc<RCU>, Key, T, Traits >::type
99 typedef ellen_bintree::details::make_ellen_bintree_map< cds::urcu::gc<RCU>, Key, T, Traits > maker;
100 typedef typename maker::type base_class;
103 typedef cds::urcu::gc<RCU> gc ; ///< RCU Garbage collector
104 typedef Key key_type ; ///< type of a key stored in the map
105 typedef T mapped_type ; ///< type of value stored in the map
106 typedef std::pair< key_type const, mapped_type > value_type ; ///< Key-value pair stored in leaf node of the mp
107 typedef Traits options ; ///< Traits template parameter
109 # ifdef CDS_DOXYGEN_INVOKED
110 typedef implementation_defined key_comparator ; ///< key compare functor based on opt::compare and opt::less option setter.
112 typedef typename maker::intrusive_type_traits::compare key_comparator;
114 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
115 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
116 typedef typename base_class::node_allocator node_allocator_type ; ///< allocator for maintaining internal node
117 typedef typename base_class::stat stat ; ///< internal statistics type
118 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< Deadlock checking policy
119 typedef typename options::copy_policy copy_policy ; ///< key copy policy
121 typedef typename options::allocator allocator_type ; ///< Allocator for leaf nodes
122 typedef typename base_class::node_allocator node_allocator ; ///< Internal node allocator
123 typedef typename base_class::update_desc_allocator update_desc_allocator ; ///< Update descriptor allocator
125 static CDS_CONSTEXPR_CONST bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
129 typedef typename base_class::value_type leaf_node;
130 typedef typename base_class::internal_node internal_node;
131 typedef typename base_class::update_desc update_desc;
133 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
135 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
139 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
141 /// pointer to extracted node
142 typedef cds::urcu::exempt_ptr< gc, leaf_node, value_type, typename maker::intrusive_type_traits::disposer,
143 cds::urcu::details::conventional_exempt_member_cast<leaf_node, value_type>
147 /// Default constructor
156 /// Inserts new node with key and default value
158 The function creates a node with \p key and default value, and then inserts the node created into the map.
161 - The \ref key_type should be constructible from a value of type \p K.
162 In trivial case, \p K is equal to \ref key_type.
163 - The \ref mapped_type should be default-constructible.
165 RCU \p synchronize method can be called. RCU should not be locked.
167 Returns \p true if inserting successful, \p false otherwise.
169 template <typename K>
170 bool insert( K const& key )
172 return insert_key( key, [](value_type&){} );
177 The function creates a node with copy of \p val value
178 and then inserts the node created into the map.
181 - The \ref key_type should be constructible from \p key of type \p K.
182 - The \ref value_type should be constructible from \p val of type \p V.
184 RCU \p synchronize method can be called. RCU should not be locked.
186 Returns \p true if \p val is inserted into the map, \p false otherwise.
188 template <typename K, typename V>
189 bool insert( K const& key, V const& val )
191 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key, val ));
192 if ( base_class::insert( *pNode ))
200 /// Inserts new node and initialize it by a functor
202 This function inserts new node with key \p key and if inserting is successful then it calls
203 \p func functor with signature
206 void operator()( value_type& item );
210 The argument \p item of user-defined functor \p func is the reference
211 to the map's item inserted:
212 - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
213 - <tt>item.second</tt> is a reference to item's value that may be changed.
215 The user-defined functor can be passed by reference using \p std::ref
216 and it is called only if inserting is successful.
218 The key_type should be constructible from value of type \p K.
220 The function allows to split creating of new item into two part:
221 - create item from \p key;
222 - insert new item into the map;
223 - if inserting is successful, initialize the value of item by calling \p func functor
225 This can be useful if complete initialization of object of \p value_type is heavyweight and
226 it is preferable that the initialization should be completed only if inserting is successful.
228 RCU \p synchronize method can be called. RCU should not be locked.
230 template <typename K, typename Func>
231 bool insert_key( const K& key, Func func )
233 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
234 if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { func( item.m_Value ); } )) {
241 /// For key \p key inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
243 Returns \p true if inserting successful, \p false otherwise.
245 RCU \p synchronize method can be called. RCU should not be locked.
247 template <typename K, typename... Args>
248 bool emplace( K&& key, Args&&... args )
250 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
251 if ( base_class::insert( *pNode )) {
258 /// Ensures that the \p key exists in the map
260 The operation performs inserting or changing data with lock-free manner.
262 If the \p key not found in the map, then the new item created from \p key
263 is inserted into the map (note that in this case the \ref key_type should be
264 constructible from type \p K).
265 Otherwise, the functor \p func is called with item found.
266 The functor \p Func may be a function with signature:
268 void func( bool bNew, value_type& item );
273 void operator()( bool bNew, value_type& item );
278 - \p bNew - \p true if the item has been inserted, \p false otherwise
279 - \p item - item of the list
281 The functor may change any fields of the \p item.second that is \ref value_type.
283 You may pass \p func argument by reference using \p std::ref
285 RCU \p synchronize method can be called. RCU should not be locked.
287 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
288 \p second is true if new item has been added or \p false if the item with \p key
289 already is in the list.
291 template <typename K, typename Func>
292 std::pair<bool, bool> ensure( K const& key, Func func )
294 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
295 std::pair<bool, bool> res = base_class::ensure( *pNode,
296 [&func](bool bNew, leaf_node& item, leaf_node const& ){ func( bNew, item.m_Value ); }
298 if ( res.first && res.second )
303 /// Delete \p key from the map
304 /**\anchor cds_nonintrusive_EllenBinTreeMap_rcu_erase_val
306 RCU \p synchronize method can be called. RCU should not be locked.
308 Return \p true if \p key is found and deleted, \p false otherwise
310 template <typename K>
311 bool erase( K const& key )
313 return base_class::erase(key);
316 /// Deletes the item from the map using \p pred predicate for searching
318 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_val "erase(K 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 map.
323 template <typename K, typename Less>
324 bool erase_with( K const& key, Less pred )
326 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
329 /// Delete \p key from the map
330 /** \anchor cds_nonintrusive_EllenBinTreeMap_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& item) { ... }
341 The functor may be passed by reference using <tt>boost:ref</tt>
343 RCU \p synchronize method can be called. RCU should not be locked.
345 Return \p true if key is found and deleted, \p false otherwise
347 template <typename K, typename Func>
348 bool erase( K const& key, Func f )
350 return base_class::erase( key, [&f]( leaf_node& node) { f( node.m_Value ); } );
353 /// Deletes the item from the map using \p pred predicate for searching
355 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_func "erase(K const&, Func)"
356 but \p pred is used for key comparing.
357 \p Less functor has the interface like \p std::less.
358 \p Less must imply the same element order as the comparator used for building the map.
360 template <typename K, typename Less, typename Func>
361 bool erase_with( K const& key, Less pred, Func f )
363 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
364 [&f]( leaf_node& node) { f( node.m_Value ); } );
367 /// Extracts an item with minimal key from the map
369 If the map is not empty, the function returns \p true, \p result contains a pointer to value.
370 If the map is empty, the function returns \p false, \p result is left unchanged.
372 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
373 It means that the function gets leftmost leaf of the tree and tries to unlink it.
374 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
375 So, the function returns the item with minimum key at the moment of tree traversing.
377 RCU \p synchronize method can be called. RCU should NOT be locked.
378 The function does not free the item.
379 The deallocator will be implicitly invoked when \p result object is destroyed or when
380 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
381 @note Before reusing \p result object you should call its \p release() method.
383 bool extract_min( exempt_ptr& result )
385 return base_class::extract_min_( result );
388 /// Extracts an item with maximal key from the map
390 If the map is not empty, the function returns \p true, \p result contains a pointer to extracted item.
391 If the map is empty, the function returns \p false, \p result is left unchanged.
393 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
394 It means that the function gets rightmost leaf of the tree and tries to unlink it.
395 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
396 So, the function returns the item with maximum key at the moment of tree traversing.
398 RCU \p synchronize method can be called. RCU should NOT be locked.
399 The function does not free the item.
400 The deallocator will be implicitly invoked when \p result object is destroyed or when
401 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
402 @note Before reusing \p result object you should call its \p release() method.
404 bool extract_max( exempt_ptr& result )
406 return base_class::extract_max_( result );
409 /// Extracts an item from the map
410 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_extract
411 The function searches an item with key equal to \p key in the tree,
412 unlinks it, and returns pointer to an item found in \p result parameter.
413 If \p key is not found the function returns \p false.
415 RCU \p synchronize method can be called. RCU should NOT be locked.
416 The function does not destroy the item found.
417 The dealloctor will be implicitly invoked when \p result object is destroyed or when
418 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
419 @note Before reusing \p result object you should call its \p release() method.
421 template <typename Q>
422 bool extract( exempt_ptr& result, Q const& key )
424 return base_class::extract_( result, key, typename base_class::node_compare());
427 /// Extracts an item from the map using \p pred for searching
429 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_extract "extract(exempt_ptr&, Q const&)"
430 but \p pred is used for key compare.
431 \p Less has the interface like \p std::less and should meet \ref cds_container_EllenBinTreeSet_rcu_less
432 "predicate requirements".
433 \p pred must imply the same element order as the comparator used for building the map.
435 template <typename Q, typename Less>
436 bool extract_with( exempt_ptr& result, Q const& val, Less pred )
438 return base_class::extract_with_( result, val,
439 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
442 /// Find the key \p key
443 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc
445 The function searches the item with key equal to \p key and calls the functor \p f for item found.
446 The interface of \p Func functor is:
449 void operator()( value_type& item );
452 where \p item is the item found.
454 You can pass \p f argument by reference using \p std::ref
456 The functor may change \p item.second.
458 The function applies RCU lock internally.
460 The function returns \p true if \p key is found, \p false otherwise.
462 template <typename K, typename Func>
463 bool find( K const& key, Func f )
465 return base_class::find( key, [&f](leaf_node& item, K const& ) { f( item.m_Value );});
468 /// Finds the key \p val using \p pred predicate for searching
470 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc "find(K const&, Func)"
471 but \p pred is used for key comparing.
472 \p Less functor has the interface like \p std::less.
473 \p Less must imply the same element order as the comparator used for building the map.
475 template <typename K, typename Less, typename Func>
476 bool find_with( K const& key, Less pred, Func f )
478 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
479 [&f](leaf_node& item, K const& ) { f( item.m_Value );});
482 /// Find the key \p key
483 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_val
485 The function searches the item with key equal to \p key
486 and returns \p true if it is found, and \p false otherwise.
488 The function applies RCU lock internally.
490 template <typename K>
491 bool find( K const& key )
493 return base_class::find( key );
496 /// Finds the key \p val using \p pred predicate for searching
498 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_val "find(K const&)"
499 but \p pred is used for key comparing.
500 \p Less functor has the interface like \p std::less.
501 \p Less must imply the same element order as the comparator used for building the map.
503 template <typename K, typename Less>
504 bool find_with( K const& key, Less pred )
506 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
509 /// Finds \p key and return the item found
510 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_get
511 The function searches the item with key equal to \p key and returns the pointer to item found.
512 If \p key is not found it returns \p nullptr.
514 RCU should be locked before call the function.
515 Returned pointer is valid while RCU is locked.
517 template <typename Q>
518 value_type * get( Q const& key ) const
520 leaf_node * pNode = base_class::get( key );
521 return pNode ? &pNode->m_Value : nullptr;
524 /// Finds \p key with \p pred predicate and return the item found
526 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_get "get(Q const&)"
527 but \p pred is used for comparing the keys.
529 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type
530 and \p Q in any order.
531 \p pred must imply the same element order as the comparator used for building the map.
533 template <typename Q, typename Less>
534 value_type * get_with( Q const& key, Less pred ) const
536 leaf_node * pNode = base_class::get_with( key,
537 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
538 return pNode ? &pNode->m_Value : nullptr;
547 /// Checks if the map is empty
549 Emptiness is checked by item counting: if item count is zero then the map is empty.
553 return base_class::empty();
556 /// Returns item count in the map
559 return base_class::size();
562 /// Returns const reference to internal statistics
563 stat const& statistics() const
565 return base_class::statistics();
568 /// Checks internal consistency (not atomic, not thread-safe)
570 The debugging function to check internal consistency of the tree.
572 bool check_consistency() const
574 return base_class::check_consistency();
578 }} // namespace cds::container
580 #endif //#ifndef __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H