3 #ifndef __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H
4 #define __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H
6 #include <cds/container/ellen_bintree_base.h>
7 #include <cds/intrusive/ellen_bintree_rcu.h>
8 #include <cds/details/functor_wrapper.h>
10 namespace cds { namespace container {
12 /// Map based on Ellen's et al binary search tree (RCU specialization)
13 /** @ingroup cds_nonintrusive_map
14 @ingroup cds_nonintrusive_tree
15 @anchor cds_container_EllenBinTreeMap_rcu
18 - [2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"
20 %EllenBinTreeMap is an unbalanced leaf-oriented binary search tree that implements the <i>map</i>
21 abstract data type. Nodes maintains child pointers but not parent pointers.
22 Every internal node has exactly two children, and all data of type <tt>std::pair<Key const, T></tt>
23 currently in the tree are stored in the leaves. Internal nodes of the tree are used to direct \p find
24 operation along the path to the correct leaf. The keys (of \p Key type) stored in internal nodes
25 may or may not be in the map.
26 Unlike \ref cds_container_EllenBinTreeSet_rcu "EllenBinTreeSet" keys are not a part of \p T type.
27 The map can be represented as a set containing <tt>std::pair< Key const, T> </tt> values.
29 Due to \p extract_min and \p extract_max member functions the \p %EllenBinTreeMap can act as
30 a <i>priority queue</i>. In this case you should provide unique compound key, for example,
31 the priority value plus some uniformly distributed random value.
33 @warning Recall the tree is <b>unbalanced</b>. The complexity of operations is <tt>O(log N)</tt>
34 for uniformly distributed random keys, but in worst case the complexity is <tt>O(N)</tt>.
36 @note In the current implementation we do not use helping technique described in original paper.
37 So, the current implementation is near to fine-grained lock-based tree.
38 Helping will be implemented in future release
40 <b>Template arguments</b> :
41 - \p RCU - one of \ref cds_urcu_gc "RCU type"
43 - \p T - value type to be stored in tree's leaf nodes.
44 - \p Traits - type traits. See ellen_bintree::type_traits for explanation.
46 It is possible to declare option-based tree with ellen_bintree::make_map_traits metafunction
47 instead of \p Traits template argument.
48 Template argument list \p Options of ellen_bintree::make_map_traits metafunction are:
49 - opt::compare - key compare functor. No default functor is provided.
50 If the option is not specified, \p %opt::less is used.
51 - opt::less - specifies binary predicate used for key compare. At least \p %opt::compare or \p %opt::less should be defined.
52 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
53 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
54 or opt::v::sequential_consistent (sequentially consisnent memory model).
55 - opt::allocator - the allocator used for \ref ellen_bintree::map_node "leaf nodes" which contains data.
56 Default is \ref CDS_DEFAULT_ALLOCATOR.
57 - opt::node_allocator - the allocator used for \ref ellen_bintree::internal_node "internal nodes".
58 Default is \ref CDS_DEFAULT_ALLOCATOR.
59 - ellen_bintree::update_desc_allocator - an allocator of \ref ellen_bintree::update_desc "update descriptors",
60 default is \ref CDS_DEFAULT_ALLOCATOR.
61 Note that update descriptor is helping data structure with short lifetime and it is good candidate for pooling.
62 The number of simultaneously existing descriptors is a relatively small number limited the number of threads
63 working with the tree and RCU buffer size.
64 Therefore, a bounded lock-free container like \p cds::container::VyukovMPMCCycleQueue is good choice for the free-list
65 of update descriptors, see cds::memory::vyukov_queue_pool free-list implementation.
66 Also notice that size of update descriptor is not dependent on the type of data
67 stored in the tree so single free-list object can be used for several EllenBinTree-based object.
68 - opt::stat - internal statistics. Available types: ellen_bintree::stat, ellen_bintree::empty_stat (the default)
69 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
70 - opt::copy_policy - key copy policy defines a functor to copy leaf node's key to internal node.
71 By default, assignment operator is used.
72 The copy functor interface is:
75 void operator()( Key& dest, Key const& src );
79 @note Before including <tt><cds/container/ellen_bintree_map_rcu.h></tt> you should include appropriate RCU header file,
80 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
86 #ifdef CDS_DOXYGEN_INVOKED
87 class Traits = ellen_bintree::type_traits
92 class EllenBinTreeMap< cds::urcu::gc<RCU>, Key, T, Traits >
93 #ifdef CDS_DOXYGEN_INVOKED
94 : public cds::intrusive::EllenBinTree< cds::urcu::gc<RCU>, Key, T, Traits >
96 : public ellen_bintree::details::make_ellen_bintree_map< cds::urcu::gc<RCU>, Key, T, Traits >::type
100 typedef ellen_bintree::details::make_ellen_bintree_map< cds::urcu::gc<RCU>, Key, T, Traits > maker;
101 typedef typename maker::type base_class;
104 typedef cds::urcu::gc<RCU> gc ; ///< RCU Garbage collector
105 typedef Key key_type ; ///< type of a key stored in the map
106 typedef T mapped_type ; ///< type of value stored in the map
107 typedef std::pair< key_type const, mapped_type > value_type ; ///< Key-value pair stored in leaf node of the mp
108 typedef Traits options ; ///< Traits template parameter
110 # ifdef CDS_DOXYGEN_INVOKED
111 typedef implementation_defined key_comparator ; ///< key compare functor based on opt::compare and opt::less option setter.
113 typedef typename maker::intrusive_type_traits::compare key_comparator;
115 typedef typename base_class::item_counter item_counter ; ///< Item counting policy used
116 typedef typename base_class::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option
117 typedef typename base_class::node_allocator node_allocator_type ; ///< allocator for maintaining internal node
118 typedef typename base_class::stat stat ; ///< internal statistics type
119 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< Deadlock checking policy
120 typedef typename options::copy_policy copy_policy ; ///< key copy policy
122 typedef typename options::allocator allocator_type ; ///< Allocator for leaf nodes
123 typedef typename base_class::node_allocator node_allocator ; ///< Internal node allocator
124 typedef typename base_class::update_desc_allocator update_desc_allocator ; ///< Update descriptor allocator
126 static CDS_CONSTEXPR_CONST bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
130 typedef typename base_class::value_type leaf_node;
131 typedef typename base_class::internal_node internal_node;
132 typedef typename base_class::update_desc update_desc;
134 typedef typename maker::cxx_leaf_node_allocator cxx_leaf_node_allocator;
136 typedef std::unique_ptr< leaf_node, typename maker::leaf_deallocator > scoped_node_ptr;
140 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
142 /// pointer to extracted node
143 typedef cds::urcu::exempt_ptr< gc, leaf_node, value_type, typename maker::intrusive_type_traits::disposer,
144 cds::urcu::details::conventional_exempt_member_cast<leaf_node, value_type>
148 /// Default constructor
157 /// Inserts new node with key and default value
159 The function creates a node with \p key and default value, and then inserts the node created into the map.
162 - The \ref key_type should be constructible from a value of type \p K.
163 In trivial case, \p K is equal to \ref key_type.
164 - The \ref mapped_type should be default-constructible.
166 RCU \p synchronize method can be called. RCU should not be locked.
168 Returns \p true if inserting successful, \p false otherwise.
170 template <typename K>
171 bool insert( K const& key )
173 return insert_key( key, [](value_type&){} );
178 The function creates a node with copy of \p val value
179 and then inserts the node created into the map.
182 - The \ref key_type should be constructible from \p key of type \p K.
183 - The \ref value_type should be constructible from \p val of type \p V.
185 RCU \p synchronize method can be called. RCU should not be locked.
187 Returns \p true if \p val is inserted into the map, \p false otherwise.
189 template <typename K, typename V>
190 bool insert( K const& key, V const& val )
192 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key, val ));
193 if ( base_class::insert( *pNode ))
201 /// Inserts new node and initialize it by a functor
203 This function inserts new node with key \p key and if inserting is successful then it calls
204 \p func functor with signature
207 void operator()( value_type& item );
211 The argument \p item of user-defined functor \p func is the reference
212 to the map's item inserted:
213 - <tt>item.first</tt> is a const reference to item's key that cannot be changed.
214 - <tt>item.second</tt> is a reference to item's value that may be changed.
216 The user-defined functor can be passed by reference using <tt>boost::ref</tt>
217 and it is called only if inserting is successful.
219 The key_type should be constructible from value of type \p K.
221 The function allows to split creating of new item into two part:
222 - create item from \p key;
223 - insert new item into the map;
224 - if inserting is successful, initialize the value of item by calling \p func functor
226 This can be useful if complete initialization of object of \p value_type is heavyweight and
227 it is preferable that the initialization should be completed only if inserting is successful.
229 RCU \p synchronize method can be called. RCU should not be locked.
231 template <typename K, typename Func>
232 bool insert_key( const K& key, Func func )
234 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
235 if ( base_class::insert( *pNode, [&func]( leaf_node& item ) { cds::unref(func)( item.m_Value ); } )) {
242 /// For key \p key inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
244 Returns \p true if inserting successful, \p false otherwise.
246 RCU \p synchronize method can be called. RCU should not be locked.
248 template <typename K, typename... Args>
249 bool emplace( K&& key, Args&&... args )
251 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( std::forward<K>(key), std::forward<Args>(args)... ));
252 if ( base_class::insert( *pNode )) {
259 /// Ensures that the \p key exists in the map
261 The operation performs inserting or changing data with lock-free manner.
263 If the \p key not found in the map, then the new item created from \p key
264 is inserted into the map (note that in this case the \ref key_type should be
265 constructible from type \p K).
266 Otherwise, the functor \p func is called with item found.
267 The functor \p Func may be a function with signature:
269 void func( bool bNew, value_type& item );
274 void operator()( bool bNew, value_type& item );
279 - \p bNew - \p true if the item has been inserted, \p false otherwise
280 - \p item - item of the list
282 The functor may change any fields of the \p item.second that is \ref value_type.
284 You may pass \p func argument by reference using <tt>boost::ref</tt>.
286 RCU \p synchronize method can be called. RCU should not be locked.
288 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
289 \p second is true if new item has been added or \p false if the item with \p key
290 already is in the list.
292 template <typename K, typename Func>
293 std::pair<bool, bool> ensure( K const& key, Func func )
295 scoped_node_ptr pNode( cxx_leaf_node_allocator().New( key ));
296 std::pair<bool, bool> res = base_class::ensure( *pNode,
297 [&func](bool bNew, leaf_node& item, leaf_node const& ){ cds::unref(func)( bNew, item.m_Value ); }
299 if ( res.first && res.second )
304 /// Delete \p key from the map
305 /**\anchor cds_nonintrusive_EllenBinTreeMap_rcu_erase_val
307 RCU \p synchronize method can be called. RCU should not be locked.
309 Return \p true if \p key is found and deleted, \p false otherwise
311 template <typename K>
312 bool erase( K const& key )
314 return base_class::erase(key);
317 /// Deletes the item from the map using \p pred predicate for searching
319 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_val "erase(K const&)"
320 but \p pred is used for key comparing.
321 \p Less functor has the interface like \p std::less.
322 \p Less must imply the same element order as the comparator used for building the map.
324 template <typename K, typename Less>
325 bool erase_with( K const& key, Less pred )
327 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
330 /// Delete \p key from the map
331 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_erase_func
333 The function searches an item with key \p key, calls \p f functor
334 and deletes the item. If \p key is not found, the functor is not called.
336 The functor \p Func interface:
339 void operator()(value_type& item) { ... }
342 The functor may be passed by reference using <tt>boost:ref</tt>
344 RCU \p synchronize method can be called. RCU should not be locked.
346 Return \p true if key is found and deleted, \p false otherwise
348 template <typename K, typename Func>
349 bool erase( K const& key, Func f )
351 return base_class::erase( key, [&f]( leaf_node& node) { cds::unref(f)( node.m_Value ); } );
354 /// Deletes the item from the map using \p pred predicate for searching
356 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_erase_func "erase(K const&, Func)"
357 but \p pred is used for key comparing.
358 \p Less functor has the interface like \p std::less.
359 \p Less must imply the same element order as the comparator used for building the map.
361 template <typename K, typename Less, typename Func>
362 bool erase_with( K const& key, Less pred, Func f )
364 return base_class::erase_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
365 [&f]( leaf_node& node) { cds::unref(f)( node.m_Value ); } );
368 /// Extracts an item with minimal key from the map
370 If the map is not empty, the function returns \p true, \p result contains a pointer to value.
371 If the map is empty, the function returns \p false, \p result is left unchanged.
373 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> minimum key.
374 It means that the function gets leftmost leaf of the tree and tries to unlink it.
375 During unlinking, a concurrent thread may insert an item with key less than leftmost item's key.
376 So, the function returns the item with minimum key at the moment of tree traversing.
378 RCU \p synchronize method can be called. RCU should NOT be locked.
379 The function does not free the item.
380 The deallocator will be implicitly invoked when \p result object is destroyed or when
381 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
382 @note Before reusing \p result object you should call its \p release() method.
384 bool extract_min( exempt_ptr& result )
386 return base_class::extract_min_( result );
389 /// Extracts an item with maximal key from the map
391 If the map is not empty, the function returns \p true, \p result contains a pointer to extracted item.
392 If the map is empty, the function returns \p false, \p result is left unchanged.
394 @note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
395 It means that the function gets rightmost leaf of the tree and tries to unlink it.
396 During unlinking, a concurrent thread may insert an item with key great than leftmost item's key.
397 So, the function returns the item with maximum key at the moment of tree traversing.
399 RCU \p synchronize method can be called. RCU should NOT be locked.
400 The function does not free the item.
401 The deallocator will be implicitly invoked when \p result object is destroyed or when
402 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
403 @note Before reusing \p result object you should call its \p release() method.
405 bool extract_max( exempt_ptr& result )
407 return base_class::extract_max_( result );
410 /// Extracts an item from the map
411 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_extract
412 The function searches an item with key equal to \p key in the tree,
413 unlinks it, and returns pointer to an item found in \p result parameter.
414 If \p key is not found the function returns \p false.
416 RCU \p synchronize method can be called. RCU should NOT be locked.
417 The function does not destroy the item found.
418 The dealloctor will be implicitly invoked when \p result object is destroyed or when
419 <tt>result.release()</tt> is called, see cds::urcu::exempt_ptr for explanation.
420 @note Before reusing \p result object you should call its \p release() method.
422 template <typename Q>
423 bool extract( exempt_ptr& result, Q const& key )
425 return base_class::extract_( result, key, typename base_class::node_compare());
428 /// Extracts an item from the map using \p pred for searching
430 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_extract "extract(exempt_ptr&, Q const&)"
431 but \p pred is used for key compare.
432 \p Less has the interface like \p std::less and should meet \ref cds_container_EllenBinTreeSet_rcu_less
433 "predicate requirements".
434 \p pred must imply the same element order as the comparator used for building the map.
436 template <typename Q, typename Less>
437 bool extract_with( exempt_ptr& result, Q const& val, Less pred )
439 return base_class::extract_with_( result, val,
440 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
443 /// Find the key \p key
444 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc
446 The function searches the item with key equal to \p key and calls the functor \p f for item found.
447 The interface of \p Func functor is:
450 void operator()( value_type& item );
453 where \p item is the item found.
455 You can pass \p f argument by reference using <tt>boost::ref</tt> or cds::ref.
457 The functor may change \p item.second.
459 The function applies RCU lock internally.
461 The function returns \p true if \p key is found, \p false otherwise.
463 template <typename K, typename Func>
464 bool find( K const& key, Func f )
466 return base_class::find( key, [&f](leaf_node& item, K const& ) { cds::unref(f)( item.m_Value );});
469 /// Finds the key \p val using \p pred predicate for searching
471 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_cfunc "find(K const&, Func)"
472 but \p pred is used for key comparing.
473 \p Less functor has the interface like \p std::less.
474 \p Less must imply the same element order as the comparator used for building the map.
476 template <typename K, typename Less, typename Func>
477 bool find_with( K const& key, Less pred, Func f )
479 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >(),
480 [&f](leaf_node& item, K const& ) { cds::unref(f)( item.m_Value );});
483 /// Find the key \p key
484 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_find_val
486 The function searches the item with key equal to \p key
487 and returns \p true if it is found, and \p false otherwise.
489 The function applies RCU lock internally.
491 template <typename K>
492 bool find( K const& key )
494 return base_class::find( key );
497 /// Finds the key \p val using \p pred predicate for searching
499 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_find_val "find(K const&)"
500 but \p pred is used for key comparing.
501 \p Less functor has the interface like \p std::less.
502 \p Less must imply the same element order as the comparator used for building the map.
504 template <typename K, typename Less>
505 bool find_with( K const& key, Less pred )
507 return base_class::find_with( key, cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >() );
510 /// Finds \p key and return the item found
511 /** \anchor cds_nonintrusive_EllenBinTreeMap_rcu_get
512 The function searches the item with key equal to \p key and returns the pointer to item found.
513 If \p key is not found it returns \p nullptr.
515 RCU should be locked before call the function.
516 Returned pointer is valid while RCU is locked.
518 template <typename Q>
519 value_type * get( Q const& key ) const
521 leaf_node * pNode = base_class::get( key );
522 return pNode ? &pNode->m_Value : nullptr;
525 /// Finds \p key with \p pred predicate and return the item found
527 The function is an analog of \ref cds_nonintrusive_EllenBinTreeMap_rcu_get "get(Q const&)"
528 but \p pred is used for comparing the keys.
530 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type
531 and \p Q in any order.
532 \p pred must imply the same element order as the comparator used for building the map.
534 template <typename Q, typename Less>
535 value_type * get_with( Q const& key, Less pred ) const
537 leaf_node * pNode = base_class::get_with( key,
538 cds::details::predicate_wrapper< leaf_node, Less, typename maker::key_accessor >());
539 return pNode ? &pNode->m_Value : nullptr;
548 /// Checks if the map is empty
550 Emptiness is checked by item counting: if item count is zero then the map is empty.
554 return base_class::empty();
557 /// Returns item count in the map
560 return base_class::size();
563 /// Returns const reference to internal statistics
564 stat const& statistics() const
566 return base_class::statistics();
569 /// Checks internal consistency (not atomic, not thread-safe)
571 The debugging function to check internal consistency of the tree.
573 bool check_consistency() const
575 return base_class::check_consistency();
579 }} // namespace cds::container
581 #endif //#ifndef __CDS_CONTAINER_ELLEN_BINTREE_MAP_RCU_H