3 #ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H
4 #define CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H
6 #include <cds/container/details/michael_set_base.h>
7 #include <cds/gc/nogc.h>
8 #include <cds/details/allocator.h>
10 namespace cds { namespace container {
12 /// Michael's hash set (template specialization for gc::nogc)
13 /** @ingroup cds_nonintrusive_set
14 \anchor cds_nonintrusive_MichaelHashSet_nogc
16 This specialization is so-called append-only when no item
17 reclamation may be performed. The class does not support deleting of list item.
19 See \ref cds_nonintrusive_MichaelHashSet_hp "MichaelHashSet" for description of template parameters.
20 The template parameter \p OrderedList should be any \p gc::nogc -derived ordered list, for example,
21 \ref cds_nonintrusive_MichaelList_nogc "append-only MichaelList".
25 #ifdef CDS_DOXYGEN_INVOKED
26 class Traits = michael_set::traits
31 class MichaelHashSet< cds::gc::nogc, OrderedList, Traits >
34 typedef cds::gc::nogc gc; ///< Garbage collector
35 typedef OrderedList bucket_type; ///< type of ordered list to be used as a bucket implementation
36 typedef Traits traits; ///< Set traits
38 typedef typename bucket_type::value_type value_type; ///< type of value stored in the list
39 typedef typename bucket_type::key_comparator key_comparator; ///< key comparison functor
41 /// Hash functor for \ref value_type and all its derivatives that you use
42 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
43 typedef typename traits::item_counter item_counter; ///< Item counter type
45 /// Bucket table allocator
46 typedef cds::details::Allocator< bucket_type, typename traits::allocator > bucket_table_allocator;
50 typedef typename bucket_type::iterator bucket_iterator;
51 typedef typename bucket_type::const_iterator bucket_const_iterator;
55 item_counter m_ItemCounter; ///< Item counter
56 hash m_HashFunctor; ///< Hash functor
57 bucket_type * m_Buckets; ///< bucket table
61 const size_t m_nHashBitmask;
66 /// Calculates hash value of \p key
68 size_t hash_value( const Q& key ) const
70 return m_HashFunctor( key ) & m_nHashBitmask;
73 /// Returns the bucket (ordered list) for \p key
75 bucket_type& bucket( const Q& key )
77 return m_Buckets[ hash_value( key ) ];
84 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
85 - it has no post-increment operator
86 - it iterates items in unordered fashion
88 typedef michael_set::details::iterator< bucket_type, false > iterator;
90 /// Const forward iterator
92 For iterator's features and requirements see \ref iterator
94 typedef michael_set::details::iterator< bucket_type, true > const_iterator;
96 /// Returns a forward iterator addressing the first element in a set
98 For empty set \code begin() == end() \endcode
102 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
105 /// Returns an iterator that addresses the location succeeding the last element in a set
107 Do not use the value returned by <tt>end</tt> function to access any item.
108 The returned value can be used only to control reaching the end of the set.
109 For empty set \code begin() == end() \endcode
113 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
116 /// Returns a forward const iterator addressing the first element in a set
118 const_iterator begin() const
120 return get_const_begin();
122 const_iterator cbegin() const
124 return get_const_begin();
128 /// Returns an const iterator that addresses the location succeeding the last element in a set
130 const_iterator end() const
132 return get_const_end();
134 const_iterator cend() const
136 return get_const_end();
142 const_iterator get_const_begin() const
144 return const_iterator( const_cast<bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
146 const_iterator get_const_end() const
148 return const_iterator( const_cast<bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
153 /// Initialize hash set
155 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
156 when you create an object.
157 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
158 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
160 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
163 size_t nMaxItemCount, ///< estimation of max item count in the hash set
164 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
165 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
167 // GC and OrderedList::gc must be the same
168 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
170 // atomicity::empty_item_counter is not allowed as a item counter
171 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
172 "cds::atomicity::empty_item_counter is not allowed as a item counter");
174 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
177 /// Clears hash set and destroys it
181 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
186 The function inserts \p val in the set if it does not contain
187 an item with key equal to \p val.
189 Return an iterator pointing to inserted item if success, otherwise \ref end()
191 template <typename Q>
192 iterator insert( const Q& val )
194 bucket_type& refBucket = bucket( val );
195 bucket_iterator it = refBucket.insert( val );
197 if ( it != refBucket.end() ) {
199 return iterator( it, &refBucket, m_Buckets + bucket_count() );
205 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
207 Return an iterator pointing to inserted item if success \ref end() otherwise
209 template <typename... Args>
210 iterator emplace( Args&&... args )
212 bucket_type& refBucket = bucket( value_type(std::forward<Args>(args)...));
213 bucket_iterator it = refBucket.emplace( std::forward<Args>(args)... );
215 if ( it != refBucket.end() ) {
217 return iterator( it, &refBucket, m_Buckets + bucket_count() );
223 /// Updates the element
225 The operation performs inserting or changing data with lock-free manner.
227 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
229 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
230 item found or inserted, or \p end() if \p bAllowInsert is \p false,
231 \p second is true if new item has been added or \p false if the item is already in the set.
233 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
234 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
237 template <typename Q>
238 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
240 bucket_type& refBucket = bucket( val );
241 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
243 if ( ret.first != refBucket.end() ) {
246 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
248 return std::make_pair( end(), ret.second );
251 template <typename Q>
252 CDS_DEPRECATED("ensure() is deprecated, use update()")
253 std::pair<iterator, bool> ensure( Q const& val )
255 return update( val, true );
259 /// Checks whether the set contains \p key
261 The function searches the item with key equal to \p key
262 and returns an iterator pointed to item found if the key is found,
263 or \ref end() otherwise.
265 Note the hash functor specified for class \p Traits template parameter
266 should accept a parameter of type \p Q that can be not the same as \p value_type.
268 template <typename Q>
269 iterator contains( Q const& key )
271 bucket_type& refBucket = bucket( key );
272 bucket_iterator it = refBucket.contains( key );
273 if ( it != refBucket.end() )
274 return iterator( it, &refBucket, m_Buckets + bucket_count() );
279 template <typename Q>
280 CDS_DEPRECATED("use contains()")
281 iterator find( Q const& key )
283 return contains( key );
287 /// Checks whether the set contains \p key using \p pred predicate for searching
289 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
290 \p Less functor has the interface like \p std::less.
291 \p Less must imply the same element order as the comparator used for building the set.
293 template <typename Q, typename Less>
294 iterator contains( Q const& key, Less pred )
296 bucket_type& refBucket = bucket( key );
297 bucket_iterator it = refBucket.contains( key, pred );
298 if ( it != refBucket.end() )
299 return iterator( it, &refBucket, m_Buckets + bucket_count() );
304 template <typename Q, typename Less>
305 CDS_DEPRECATED("use contains()")
306 iterator find_with( Q const& key, Less pred )
308 return contains( key, pred );
312 /// Clears the set (not atomic)
315 for ( size_t i = 0; i < bucket_count(); ++i )
316 m_Buckets[i].clear();
317 m_ItemCounter.reset();
320 /// Checks if the set is empty
322 The emptiness is checked by the item counting: if item count is zero then the set is empty.
323 Thus, the correct item counting feature is an important part of Michael's set implementation.
330 /// Returns item count in the set
333 return m_ItemCounter;
336 /// Returns the size of hash table
338 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
339 the value returned is an constant depending on object initialization parameters;
340 see MichaelHashSet::MichaelHashSet for explanation.
342 size_t bucket_count() const
344 return m_nHashBitmask + 1;
350 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H