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;
49 typedef cds::container::michael_set::implementation_tag implementation_tag;
54 typedef typename bucket_type::iterator bucket_iterator;
55 typedef typename bucket_type::const_iterator bucket_const_iterator;
59 item_counter m_ItemCounter; ///< Item counter
60 hash m_HashFunctor; ///< Hash functor
61 bucket_type * m_Buckets; ///< bucket table
65 const size_t m_nHashBitmask;
70 /// Calculates hash value of \p key
72 size_t hash_value( const Q& key ) const
74 return m_HashFunctor( key ) & m_nHashBitmask;
77 /// Returns the bucket (ordered list) for \p key
79 bucket_type& bucket( const Q& key )
81 return m_Buckets[ hash_value( key ) ];
88 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
89 - it has no post-increment operator
90 - it iterates items in unordered fashion
92 typedef michael_set::details::iterator< bucket_type, false > iterator;
94 /// Const forward iterator
96 For iterator's features and requirements see \ref iterator
98 typedef michael_set::details::iterator< bucket_type, true > const_iterator;
100 /// Returns a forward iterator addressing the first element in a set
102 For empty set \code begin() == end() \endcode
106 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
109 /// Returns an iterator that addresses the location succeeding the last element in a set
111 Do not use the value returned by <tt>end</tt> function to access any item.
112 The returned value can be used only to control reaching the end of the set.
113 For empty set \code begin() == end() \endcode
117 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
120 /// Returns a forward const iterator addressing the first element in a set
122 const_iterator begin() const
124 return get_const_begin();
126 const_iterator cbegin() const
128 return get_const_begin();
132 /// Returns an const iterator that addresses the location succeeding the last element in a set
134 const_iterator end() const
136 return get_const_end();
138 const_iterator cend() const
140 return get_const_end();
146 const_iterator get_const_begin() const
148 return const_iterator( const_cast<bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
150 const_iterator get_const_end() const
152 return const_iterator( const_cast<bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
157 /// Initialize hash set
159 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
160 when you create an object.
161 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
162 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
164 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
167 size_t nMaxItemCount, ///< estimation of max item count in the hash set
168 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
169 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
171 // GC and OrderedList::gc must be the same
172 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
174 // atomicity::empty_item_counter is not allowed as a item counter
175 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
176 "cds::atomicity::empty_item_counter is not allowed as a item counter");
178 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
181 /// Clears hash set and destroys it
185 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
190 The function inserts \p val in the set if it does not contain
191 an item with key equal to \p val.
193 Return an iterator pointing to inserted item if success, otherwise \ref end()
195 template <typename Q>
196 iterator insert( const Q& val )
198 bucket_type& refBucket = bucket( val );
199 bucket_iterator it = refBucket.insert( val );
201 if ( it != refBucket.end() ) {
203 return iterator( it, &refBucket, m_Buckets + bucket_count() );
209 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
211 Return an iterator pointing to inserted item if success \ref end() otherwise
213 template <typename... Args>
214 iterator emplace( Args&&... args )
216 bucket_type& refBucket = bucket( value_type(std::forward<Args>(args)...));
217 bucket_iterator it = refBucket.emplace( std::forward<Args>(args)... );
219 if ( it != refBucket.end() ) {
221 return iterator( it, &refBucket, m_Buckets + bucket_count() );
227 /// Updates the element
229 The operation performs inserting or changing data with lock-free manner.
231 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
233 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
234 item found or inserted, or \p end() if \p bAllowInsert is \p false,
235 \p second is true if new item has been added or \p false if the item is already in the set.
237 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
238 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
241 template <typename Q>
242 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
244 bucket_type& refBucket = bucket( val );
245 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
247 if ( ret.first != refBucket.end() ) {
250 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
252 return std::make_pair( end(), ret.second );
255 template <typename Q>
256 CDS_DEPRECATED("ensure() is deprecated, use update()")
257 std::pair<iterator, bool> ensure( Q const& val )
259 return update( val, true );
263 /// Checks whether the set contains \p key
265 The function searches the item with key equal to \p key
266 and returns an iterator pointed to item found if the key is found,
267 or \ref end() otherwise.
269 Note the hash functor specified for class \p Traits template parameter
270 should accept a parameter of type \p Q that can be not the same as \p value_type.
272 template <typename Q>
273 iterator contains( Q const& key )
275 bucket_type& refBucket = bucket( key );
276 bucket_iterator it = refBucket.contains( key );
277 if ( it != refBucket.end() )
278 return iterator( it, &refBucket, m_Buckets + bucket_count() );
283 template <typename Q>
284 CDS_DEPRECATED("use contains()")
285 iterator find( Q const& key )
287 return contains( key );
291 /// Checks whether the set contains \p key using \p pred predicate for searching
293 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
294 \p Less functor has the interface like \p std::less.
295 \p Less must imply the same element order as the comparator used for building the set.
297 template <typename Q, typename Less>
298 iterator contains( Q const& key, Less pred )
300 bucket_type& refBucket = bucket( key );
301 bucket_iterator it = refBucket.contains( key, pred );
302 if ( it != refBucket.end() )
303 return iterator( it, &refBucket, m_Buckets + bucket_count() );
308 template <typename Q, typename Less>
309 CDS_DEPRECATED("use contains()")
310 iterator find_with( Q const& key, Less pred )
312 return contains( key, pred );
316 /// Clears the set (not atomic)
319 for ( size_t i = 0; i < bucket_count(); ++i )
320 m_Buckets[i].clear();
321 m_ItemCounter.reset();
324 /// Checks if the set is empty
326 The emptiness is checked by the item counting: if item count is zero then the set is empty.
327 Thus, the correct item counting feature is an important part of Michael's set implementation.
334 /// Returns item count in the set
337 return m_ItemCounter;
340 /// Returns the size of hash table
342 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
343 the value returned is an constant depending on object initialization parameters;
344 see MichaelHashSet::MichaelHashSet for explanation.
346 size_t bucket_count() const
348 return m_nHashBitmask + 1;
354 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H