3 #ifndef __CDS_CONTAINER_MICHAEL_SET_NOGC_H
4 #define __CDS_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
154 /** @copydetails cds_nonintrusive_MichaelHashSet_hp_ctor
157 size_t nMaxItemCount, ///< estimation of max item count in the hash set
158 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
159 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
161 // GC and OrderedList::gc must be the same
162 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
164 // atomicity::empty_item_counter is not allowed as a item counter
165 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
166 "cds::atomicity::empty_item_counter is not allowed as a item counter");
168 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
171 /// Clears hash set and destroys it
175 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
180 The function inserts \p val in the set if it does not contain
181 an item with key equal to \p val.
183 Return an iterator pointing to inserted item if success, otherwise \ref end()
185 template <typename Q>
186 iterator insert( const Q& val )
188 bucket_type& refBucket = bucket( val );
189 bucket_iterator it = refBucket.insert( val );
191 if ( it != refBucket.end() ) {
193 return iterator( it, &refBucket, m_Buckets + bucket_count() );
199 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
201 Return an iterator pointing to inserted item if success \ref end() otherwise
203 template <typename... Args>
204 iterator emplace( Args&&... args )
206 bucket_type& refBucket = bucket( value_type(std::forward<Args>(args)...));
207 bucket_iterator it = refBucket.emplace( std::forward<Args>(args)... );
209 if ( it != refBucket.end() ) {
211 return iterator( it, &refBucket, m_Buckets + bucket_count() );
217 /// Ensures that the item \p val exists in the set
219 The operation inserts new item if the key \p val is not found in the set.
220 Otherwise, the function returns an iterator that points to item found.
222 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
223 item found or inserted, \p second is true if new item has been added or \p false if the item
224 already is in the set.
226 @warning For \ref cds_nonintrusive_MichaelList_nogc "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
227 \ref cds_nonintrusive_LazyList_nogc "LazyList" provides exclusive access to inserted item and does not require any node-level
230 template <typename Q>
231 std::pair<iterator, bool> ensure( const Q& val )
233 bucket_type& refBucket = bucket( val );
234 std::pair<bucket_iterator, bool> ret = refBucket.ensure( val );
236 if ( ret.first != refBucket.end() ) {
239 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
242 return std::make_pair( end(), ret.second );
245 /// Find the key \p key
246 /** \anchor cds_nonintrusive_MichealSet_nogc_find
247 The function searches the item with key equal to \p key
248 and returns an iterator pointed to item found if the key is found,
249 and \ref end() otherwise
251 template <typename Q>
252 iterator find( Q const& key )
254 bucket_type& refBucket = bucket( key );
255 bucket_iterator it = refBucket.find( key );
256 if ( it != refBucket.end() )
257 return iterator( it, &refBucket, m_Buckets + bucket_count() );
262 /// Finds the key \p val using \p pred predicate for searching
264 The function is an analog of \ref cds_nonintrusive_MichealSet_nogc_find "find(Q const&)"
265 but \p pred is used for key comparing.
266 \p Less functor has the interface like \p std::less.
267 \p Less must imply the same element order as the comparator used for building the set.
269 template <typename Q, typename Less>
270 iterator find_with( Q const& key, Less pred )
272 bucket_type& refBucket = bucket( key );
273 bucket_iterator it = refBucket.find_with( key, pred );
274 if ( it != refBucket.end() )
275 return iterator( it, &refBucket, m_Buckets + bucket_count() );
280 /// Clears the set (not atomic)
283 for ( size_t i = 0; i < bucket_count(); ++i )
284 m_Buckets[i].clear();
285 m_ItemCounter.reset();
288 /// Checks if the set is empty
290 The emptiness is checked by the item counting: if item count is zero then the set is empty.
291 Thus, the correct item counting feature is an important part of Michael's set implementation.
298 /// Returns item count in the set
301 return m_ItemCounter;
304 /// Returns the size of hash table
306 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
307 the value returned is an constant depending on object initialization parameters;
308 see MichaelHashSet::MichaelHashSet for explanation.
310 size_t bucket_count() const
312 return m_nHashBitmask + 1;
318 #endif // ifndef __CDS_CONTAINER_MICHAEL_SET_NOGC_H