2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
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31 #ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H
32 #define CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H
34 #include <cds/container/details/michael_set_base.h>
35 #include <cds/gc/nogc.h>
37 namespace cds { namespace container {
39 /// Michael's hash set (template specialization for gc::nogc)
40 /** @ingroup cds_nonintrusive_set
41 \anchor cds_nonintrusive_MichaelHashSet_nogc
43 This specialization is so-called append-only when no item
44 reclamation may be performed. The class does not support deleting of list item.
46 See \ref cds_nonintrusive_MichaelHashSet_hp "MichaelHashSet" for description of template parameters.
47 The template parameter \p OrderedList should be any \p gc::nogc -derived ordered list, for example,
48 \ref cds_nonintrusive_MichaelList_nogc "append-only MichaelList".
52 #ifdef CDS_DOXYGEN_INVOKED
53 class Traits = michael_set::traits
58 class MichaelHashSet< cds::gc::nogc, OrderedList, Traits >
61 typedef cds::gc::nogc gc; ///< Garbage collector
62 typedef OrderedList ordered_list; ///< type of ordered list to be used as a bucket implementation
63 typedef Traits traits; ///< Set traits
65 typedef typename ordered_list::value_type value_type; ///< type of value stored in the list
66 typedef typename ordered_list::key_comparator key_comparator; ///< key comparison functor
67 #ifdef CDS_DOXYGEN_INVOKED
68 typedef typename ordered_list::stat stat; ///< Internal statistics
71 /// Hash functor for \ref value_type and all its derivatives that you use
72 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
73 typedef typename traits::item_counter item_counter; ///< Item counter type
74 typedef typename traits::allocator allocator; ///< Bucket table allocator
76 // GC and OrderedList::gc must be the same
77 static_assert(std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
79 // atomicity::empty_item_counter is not allowed as a item counter
80 static_assert(!std::is_same<item_counter, atomicity::empty_item_counter>::value,
81 "cds::atomicity::empty_item_counter is not allowed as a item counter");
85 typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat;
87 typedef typename ordered_list::template rebind_traits<
88 cds::opt::item_counter< cds::atomicity::empty_item_counter >
89 , cds::opt::stat< typename bucket_stat::wrapped_stat >
90 >::type internal_bucket_type_;
92 class internal_bucket_type: public internal_bucket_type_
94 typedef internal_bucket_type_ base_class;
96 using base_class::base_class;
97 using typename base_class::node_type;
98 using base_class::alloc_node;
99 using base_class::insert_node;
100 using base_class::node_to_value;
103 /// Bucket table allocator
104 typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator;
106 typedef typename internal_bucket_type::iterator bucket_iterator;
107 typedef typename internal_bucket_type::const_iterator bucket_const_iterator;
112 typedef typename bucket_stat::stat stat;
117 const size_t m_nHashBitmask;
118 item_counter m_ItemCounter; ///< Item counter
119 hash m_HashFunctor; ///< Hash functor
120 internal_bucket_type* m_Buckets; ///< bucket table
121 stat m_Stat; ///< Internal statistics
125 ///@name Forward iterators
129 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
130 - it has no post-increment operator
131 - it iterates items in unordered fashion
133 The iterator interface:
137 // Default constructor
141 iterator( iterator const& src );
143 // Dereference operator
144 value_type * operator ->() const;
146 // Dereference operator
147 value_type& operator *() const;
149 // Preincrement operator
150 iterator& operator ++();
152 // Assignment operator
153 iterator& operator = (iterator const& src);
155 // Equality operators
156 bool operator ==(iterator const& i ) const;
157 bool operator !=(iterator const& i ) const;
161 typedef michael_set::details::iterator< internal_bucket_type, false > iterator;
163 /// Const forward iterator
165 For iterator's features and requirements see \ref iterator
167 typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator;
169 /// Returns a forward iterator addressing the first element in a set
171 For empty set \code begin() == end() \endcode
175 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count());
178 /// Returns an iterator that addresses the location succeeding the last element in a set
180 Do not use the value returned by <tt>end</tt> function to access any item.
181 The returned value can be used only to control reaching the end of the set.
182 For empty set \code begin() == end() \endcode
186 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
189 /// Returns a forward const iterator addressing the first element in a set
190 const_iterator begin() const
192 return get_const_begin();
195 /// Returns a forward const iterator addressing the first element in a set
196 const_iterator cbegin() const
198 return get_const_begin();
201 /// Returns an const iterator that addresses the location succeeding the last element in a set
202 const_iterator end() const
204 return get_const_end();
207 /// Returns an const iterator that addresses the location succeeding the last element in a set
208 const_iterator cend() const
210 return get_const_end();
215 /// Initialize hash set
217 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
218 when you create an object.
219 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
220 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
222 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
225 size_t nMaxItemCount, ///< estimation of max item count in the hash set
226 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
227 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
228 , m_Buckets( bucket_table_allocator().allocate( bucket_count()))
230 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
231 construct_bucket<bucket_stat>( it );
234 /// Clears hash set and destroys it
238 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
239 it->~internal_bucket_type();
240 bucket_table_allocator().deallocate( m_Buckets, bucket_count());
245 The function inserts \p val in the set if it does not contain
246 an item with key equal to \p val.
248 Return an iterator pointing to inserted item if success, otherwise \ref end()
250 template <typename Q>
251 iterator insert( const Q& val )
253 internal_bucket_type& refBucket = bucket( val );
254 bucket_iterator it = refBucket.insert( val );
256 if ( it != refBucket.end()) {
258 return iterator( it, &refBucket, m_Buckets + bucket_count());
264 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
266 Return an iterator pointing to inserted item if success \ref end() otherwise
268 template <typename... Args>
269 iterator emplace( Args&&... args )
271 typename internal_bucket_type::node_type * pNode = internal_bucket_type::alloc_node( std::forward<Args>( args )... );
272 internal_bucket_type& refBucket = bucket( internal_bucket_type::node_to_value( *pNode ));
273 bucket_iterator it = refBucket.insert_node( pNode );
274 if ( it != refBucket.end()) {
276 return iterator( it, &refBucket, m_Buckets + bucket_count());
282 /// Updates the element
284 The operation performs inserting or changing data with lock-free manner.
286 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
288 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
289 item found or inserted, or \p end() if \p bAllowInsert is \p false,
291 \p second is true if new item has been added or \p false if the item is already in the set.
293 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
294 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
297 template <typename Q>
298 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
300 internal_bucket_type& refBucket = bucket( val );
301 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
303 if ( ret.first != refBucket.end()) {
306 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count()), ret.second );
308 return std::make_pair( end(), ret.second );
311 template <typename Q>
312 CDS_DEPRECATED("ensure() is deprecated, use update()")
313 std::pair<iterator, bool> ensure( Q const& val )
315 return update( val, true );
319 /// Checks whether the set contains \p key
321 The function searches the item with key equal to \p key
322 and returns an iterator pointed to item found if the key is found,
323 or \ref end() otherwise.
325 Note the hash functor specified for class \p Traits template parameter
326 should accept a parameter of type \p Q that can be not the same as \p value_type.
328 template <typename Q>
329 iterator contains( Q const& key )
331 internal_bucket_type& refBucket = bucket( key );
332 bucket_iterator it = refBucket.contains( key );
333 if ( it != refBucket.end())
334 return iterator( it, &refBucket, m_Buckets + bucket_count());
339 template <typename Q>
340 CDS_DEPRECATED("use contains()")
341 iterator find( Q const& key )
343 return contains( key );
347 /// Checks whether the set contains \p key using \p pred predicate for searching
349 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
350 \p Less functor has the interface like \p std::less.
351 \p Less must imply the same element order as the comparator used for building the set.
353 template <typename Q, typename Less>
354 iterator contains( Q const& key, Less pred )
356 internal_bucket_type& refBucket = bucket( key );
357 bucket_iterator it = refBucket.contains( key, pred );
358 if ( it != refBucket.end())
359 return iterator( it, &refBucket, m_Buckets + bucket_count());
364 template <typename Q, typename Less>
365 CDS_DEPRECATED("use contains()")
366 iterator find_with( Q const& key, Less pred )
368 return contains( key, pred );
372 /// Clears the set (not atomic)
375 for ( size_t i = 0; i < bucket_count(); ++i )
376 m_Buckets[i].clear();
377 m_ItemCounter.reset();
380 /// Checks if the set is empty
382 The emptiness is checked by the item counting: if item count is zero then the set is empty.
383 Thus, the correct item counting feature is an important part of Michael's set implementation.
390 /// Returns item count in the set
393 return m_ItemCounter;
396 /// Returns const reference to internal statistics
397 stat const& statistics() const
402 /// Returns the size of hash table
404 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
405 the value returned is an constant depending on object initialization parameters;
406 see MichaelHashSet::MichaelHashSet for explanation.
408 size_t bucket_count() const
410 return m_nHashBitmask + 1;
415 /// Calculates hash value of \p key
416 template <typename Q>
417 size_t hash_value( const Q& key ) const
419 return m_HashFunctor( key ) & m_nHashBitmask;
422 /// Returns the bucket (ordered list) for \p key
423 template <typename Q>
424 internal_bucket_type& bucket( const Q& key )
426 return m_Buckets[hash_value( key )];
432 template <typename Stat>
433 typename std::enable_if< Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
435 new (bucket) internal_bucket_type;
438 template <typename Stat>
439 typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
441 new (bucket) internal_bucket_type( m_Stat );
444 const_iterator get_const_begin() const
446 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count());
448 const_iterator get_const_end() const
450 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
457 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H