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 key_type should be constructible from value of type \p K.
217 The function allows to split creating of new item into two part:
218 - create item from \p key;
219 - insert new item into the map;
220 - if inserting is successful, initialize the value of item by calling \p func functor
222 This can be useful if complete initialization of object of \p value_type is heavyweight and
223 it is preferable that the initialization should be completed only if inserting is successful.
225 RCU \p synchronize method can be called. RCU should not be locked.
227 template <typename K, typename Func>
228 bool insert_key( const K& key, Func func )
230 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
231 if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { func( item.m_Value ); } )) {
238 /// For key \p key inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
240 Returns \p true if inserting successful, \p false otherwise.
242 RCU \p synchronize method can be called. RCU should not be locked.
244 template <typename K, typename... Args>
245 bool emplace( K&& key, Args&&... args )
247 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
248 if ( base_class::insert( *pNode )) {
255 /// Ensures that the \p key exists in the map
257 The operation performs inserting or changing data with lock-free manner.
259 If the \p key not found in the map, then the new item created from \p key
260 is inserted into the map (note that in this case the \ref key_type should be
261 constructible from type \p K).
262 Otherwise, the functor \p func is called with item found.
263 The functor \p Func may be a function with signature:
265 void func( bool bNew, value_type& item );
270 void operator()( bool bNew, value_type& item );
275 - \p bNew - \p true if the item has been inserted, \p false otherwise
276 - \p item - item of the list
278 The functor may change any fields of the \p item.second that is \ref value_type.
280 RCU \p synchronize method can be called. RCU should not be locked.
282 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
283 \p second is true if new item has been added or \p false if the item with \p key
284 already is in the list.
286 template <typename K, typename Func>
287 std::pair<bool, bool> ensure( K const& key, Func func )
289 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
290 std::pair<bool, bool> res = base_class::ensure( *pNode,
291 [&func](bool bNew, leaf_node& item, leaf_node const& ){ func( bNew, item.m_Value ); }
293 if ( res.first && res.second )
298 /// Delete \p key from the map
299 /**\anchor cds_nonintrusive_EllenBinTreeMap_rcu_erase_val
301 RCU \p synchronize method can be called. RCU should not be locked.
303 Return \p true if \p key is found and deleted, \p false otherwise
305 template <typename K>
306 bool erase( K const& key )
308 return base_class::erase(key);
311 /// Deletes the item from the map using \p pred predicate for searching
313 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_val "erase(K const&)"
314 but \p pred is used for key comparing.
315 \p Less functor has the interface like \p std::less.
316 \p Less must imply the same element order as the comparator used for building the map.
318 template <typename K, typename Less>
319 bool erase_with( K const& key, Less pred )
321 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
324 /// Delete \p key from the map
325 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_erase_func
327 The function searches an item with key \p key, calls \p f functor
328 and deletes the item. If \p key is not found, the functor is not called.
330 The functor \p Func interface:
333 void operator()(value_type& item) { ... }
337 RCU \p synchronize method can be called. RCU should not be locked.
339 Return \p true if key is found and deleted, \p false otherwise
341 template <typename K, typename Func>
342 bool erase( K const& key, Func f )
344 return base_class::erase( key, [&f]( leaf_node& node) { f( node.m_Value ); } );
347 /// Deletes the item from the map using \p pred predicate for searching
349 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_func "erase(K const&, Func)"
350 but \p pred is used for key comparing.
351 \p Less functor has the interface like \p std::less.
352 \p Less must imply the same element order as the comparator used for building the map.
354 template <typename K, typename Less, typename Func>
355 bool erase_with( K const& key, Less pred, Func f )
357 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
358 [&f]( leaf_node& node) { f( node.m_Value ); } );
361 /// Extracts an item with minimal key from the map
363 If the map is not empty, the function returns \p true, \p result contains a pointer to value.
364 If the map is empty, the function returns \p false, \p result is left unchanged.
366 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
367 It means that the function gets leftmost leaf of the tree and tries to unlink it.
368 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
369 So, the function returns the item with minimum key at the moment of tree traversing.
371 RCU \p synchronize method can be called. RCU should NOT be locked.
372 The function does not free the item.
373 The deallocator will be implicitly invoked when \p result object is destroyed or when
374 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
375 @note Before reusing \p result object you should call its \p release() method.
377 bool extract_min( exempt_ptr& result )
379 return base_class::extract_min_( result );
382 /// Extracts an item with maximal key from the map
384 If the map is not empty, the function returns \p true, \p result contains a pointer to extracted item.
385 If the map is empty, the function returns \p false, \p result is left unchanged.
387 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
388 It means that the function gets rightmost leaf of the tree and tries to unlink it.
389 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
390 So, the function returns the item with maximum key at the moment of tree traversing.
392 RCU \p synchronize method can be called. RCU should NOT be locked.
393 The function does not free the item.
394 The deallocator will be implicitly invoked when \p result object is destroyed or when
395 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
396 @note Before reusing \p result object you should call its \p release() method.
398 bool extract_max( exempt_ptr& result )
400 return base_class::extract_max_( result );
403 /// Extracts an item from the map
404 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_extract
405 The function searches an item with key equal to \p key in the tree,
406 unlinks it, and returns pointer to an item found in \p result parameter.
407 If \p key is not found the function returns \p false.
409 RCU \p synchronize method can be called. RCU should NOT be locked.
410 The function does not destroy the item found.
411 The dealloctor will be implicitly invoked when \p result object is destroyed or when
412 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
413 @note Before reusing \p result object you should call its \p release() method.
415 template <typename Q>
416 bool extract( exempt_ptr& result, Q const& key )
418 return base_class::extract_( result, key, typename base_class::node_compare());
421 /// Extracts an item from the map using \p pred for searching
423 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_extract "extract(exempt_ptr&, Q const&)"
424 but \p pred is used for key compare.
425 \p Less has the interface like \p std::less and should meet \ref cds_container_EllenBinTreeSet_rcu_less
426 "predicate requirements".
427 \p pred must imply the same element order as the comparator used for building the map.
429 template <typename Q, typename Less>
430 bool extract_with( exempt_ptr& result, Q const& val, Less pred )
432 return base_class::extract_with_( result, val,
433 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
436 /// Find the key \p key
437 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc
439 The function searches the item with key equal to \p key and calls the functor \p f for item found.
440 The interface of \p Func functor is:
443 void operator()( value_type& item );
446 where \p item is the item found.
448 The functor may change \p item.second.
450 The function applies RCU lock internally.
452 The function returns \p true if \p key is found, \p false otherwise.
454 template <typename K, typename Func>
455 bool find( K const& key, Func f )
457 return base_class::find( key, [&f](leaf_node& item, K const& ) { f( item.m_Value );});
460 /// Finds the key \p val using \p pred predicate for searching
462 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc "find(K const&, Func)"
463 but \p pred is used for key comparing.
464 \p Less functor has the interface like \p std::less.
465 \p Less must imply the same element order as the comparator used for building the map.
467 template <typename K, typename Less, typename Func>
468 bool find_with( K const& key, Less pred, Func f )
470 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
471 [&f](leaf_node& item, K const& ) { f( item.m_Value );});
474 /// Find the key \p key
475 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_val
477 The function searches the item with key equal to \p key
478 and returns \p true if it is found, and \p false otherwise.
480 The function applies RCU lock internally.
482 template <typename K>
483 bool find( K const& key )
485 return base_class::find( key );
488 /// Finds the key \p val using \p pred predicate for searching
490 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_val "find(K const&)"
491 but \p pred is used for key comparing.
492 \p Less functor has the interface like \p std::less.
493 \p Less must imply the same element order as the comparator used for building the map.
495 template <typename K, typename Less>
496 bool find_with( K const& key, Less pred )
498 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
501 /// Finds \p key and return the item found
502 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_get
503 The function searches the item with key equal to \p key and returns the pointer to item found.
504 If \p key is not found it returns \p nullptr.
506 RCU should be locked before call the function.
507 Returned pointer is valid while RCU is locked.
509 template <typename Q>
510 value_type * get( Q const& key ) const
512 leaf_node * pNode = base_class::get( key );
513 return pNode ? &pNode->m_Value : nullptr;
516 /// Finds \p key with \p pred predicate and return the item found
518 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_get "get(Q const&)"
519 but \p pred is used for comparing the keys.
521 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type
522 and \p Q in any order.
523 \p pred must imply the same element order as the comparator used for building the map.
525 template <typename Q, typename Less>
526 value_type * get_with( Q const& key, Less pred ) const
528 leaf_node * pNode = base_class::get_with( key,
529 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
530 return pNode ? &pNode->m_Value : nullptr;
539 /// Checks if the map is empty
541 Emptiness is checked by item counting: if item count is zero then the map is empty.
545 return base_class::empty();
548 /// Returns item count in the map
551 return base_class::size();
554 /// Returns const reference to internal statistics
555 stat const& statistics() const
557 return base_class::statistics();
560 /// Checks internal consistency (not atomic, not thread-safe)
562 The debugging function to check internal consistency of the tree.
564 bool check_consistency() const
566 return base_class::check_consistency();
570 }} // namespace cds::container
572 #endif //#ifndef __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H