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");
81 typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat;
83 typedef typename ordered_list::template rebind_traits<
84 cds::opt::item_counter< cds::atomicity::empty_item_counter >
85 , cds::opt::stat< typename bucket_stat::wrapped_stat >
86 >::type internal_bucket_type_;
88 class internal_bucket_type: public internal_bucket_type_
90 typedef internal_bucket_type_ base_class;
92 using base_class::base_class;
93 using typename base_class::node_type;
94 using base_class::alloc_node;
95 using base_class::insert_node;
96 using base_class::node_to_value;
99 /// Bucket table allocator
100 typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator;
102 typedef typename internal_bucket_type::iterator bucket_iterator;
103 typedef typename internal_bucket_type::const_iterator bucket_const_iterator;
108 typedef typename bucket_stat::stat stat;
113 const size_t m_nHashBitmask;
114 hash m_HashFunctor; ///< Hash functor
115 internal_bucket_type* m_Buckets; ///< bucket table
116 item_counter m_ItemCounter; ///< Item counter
117 stat m_Stat; ///< Internal statistics
121 ///@name Forward iterators
125 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
126 - it has no post-increment operator
127 - it iterates items in unordered fashion
129 The iterator interface:
133 // Default constructor
137 iterator( iterator const& src );
139 // Dereference operator
140 value_type * operator ->() const;
142 // Dereference operator
143 value_type& operator *() const;
145 // Preincrement operator
146 iterator& operator ++();
148 // Assignment operator
149 iterator& operator = (iterator const& src);
151 // Equality operators
152 bool operator ==(iterator const& i ) const;
153 bool operator !=(iterator const& i ) const;
157 typedef michael_set::details::iterator< internal_bucket_type, false > iterator;
159 /// Const forward iterator
161 For iterator's features and requirements see \ref iterator
163 typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator;
165 /// Returns a forward iterator addressing the first element in a set
167 For empty set \code begin() == end() \endcode
171 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count());
174 /// Returns an iterator that addresses the location succeeding the last element in a set
176 Do not use the value returned by <tt>end</tt> function to access any item.
177 The returned value can be used only to control reaching the end of the set.
178 For empty set \code begin() == end() \endcode
182 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
185 /// Returns a forward const iterator addressing the first element in a set
186 const_iterator begin() const
188 return get_const_begin();
191 /// Returns a forward const iterator addressing the first element in a set
192 const_iterator cbegin() const
194 return get_const_begin();
197 /// Returns an const iterator that addresses the location succeeding the last element in a set
198 const_iterator end() const
200 return get_const_end();
203 /// Returns an const iterator that addresses the location succeeding the last element in a set
204 const_iterator cend() const
206 return get_const_end();
211 /// Initialize hash set
213 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
214 when you create an object.
215 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
216 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
218 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
221 size_t nMaxItemCount, ///< estimation of max item count in the hash set
222 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
223 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
224 , m_Buckets( bucket_table_allocator().allocate( bucket_count()))
226 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
227 construct_bucket<bucket_stat>( it );
230 /// Clears hash set and destroys it
234 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
235 it->~internal_bucket_type();
236 bucket_table_allocator().deallocate( m_Buckets, bucket_count());
241 The function inserts \p val in the set if it does not contain
242 an item with key equal to \p val.
244 Return an iterator pointing to inserted item if success, otherwise \ref end()
246 template <typename Q>
247 iterator insert( const Q& val )
249 internal_bucket_type& refBucket = bucket( val );
250 bucket_iterator it = refBucket.insert( val );
252 if ( it != refBucket.end()) {
254 return iterator( it, &refBucket, m_Buckets + bucket_count());
260 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
262 Return an iterator pointing to inserted item if success \ref end() otherwise
264 template <typename... Args>
265 iterator emplace( Args&&... args )
267 typename internal_bucket_type::node_type * pNode = internal_bucket_type::alloc_node( std::forward<Args>( args )... );
268 internal_bucket_type& refBucket = bucket( internal_bucket_type::node_to_value( *pNode ));
269 bucket_iterator it = refBucket.insert_node( pNode );
270 if ( it != refBucket.end()) {
272 return iterator( it, &refBucket, m_Buckets + bucket_count());
278 /// Updates the element
280 The operation performs inserting or changing data with lock-free manner.
282 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
284 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
285 item found or inserted, or \p end() if \p bAllowInsert is \p false,
287 \p second is true if new item has been added or \p false if the item is already in the set.
289 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
290 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
293 template <typename Q>
294 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
296 internal_bucket_type& refBucket = bucket( val );
297 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
299 if ( ret.first != refBucket.end()) {
302 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count()), ret.second );
304 return std::make_pair( end(), ret.second );
307 template <typename Q>
308 CDS_DEPRECATED("ensure() is deprecated, use update()")
309 std::pair<iterator, bool> ensure( Q const& val )
311 return update( val, true );
315 /// Checks whether the set contains \p key
317 The function searches the item with key equal to \p key
318 and returns an iterator pointed to item found if the key is found,
319 or \ref end() otherwise.
321 Note the hash functor specified for class \p Traits template parameter
322 should accept a parameter of type \p Q that can be not the same as \p value_type.
324 template <typename Q>
325 iterator contains( Q const& key )
327 internal_bucket_type& refBucket = bucket( key );
328 bucket_iterator it = refBucket.contains( key );
329 if ( it != refBucket.end())
330 return iterator( it, &refBucket, m_Buckets + bucket_count());
335 template <typename Q>
336 CDS_DEPRECATED("use contains()")
337 iterator find( Q const& key )
339 return contains( key );
343 /// Checks whether the set contains \p key using \p pred predicate for searching
345 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
346 \p Less functor has the interface like \p std::less.
347 \p Less must imply the same element order as the comparator used for building the set.
349 template <typename Q, typename Less>
350 iterator contains( Q const& key, Less pred )
352 internal_bucket_type& refBucket = bucket( key );
353 bucket_iterator it = refBucket.contains( key, pred );
354 if ( it != refBucket.end())
355 return iterator( it, &refBucket, m_Buckets + bucket_count());
360 template <typename Q, typename Less>
361 CDS_DEPRECATED("use contains()")
362 iterator find_with( Q const& key, Less pred )
364 return contains( key, pred );
368 /// Clears the set (not atomic)
371 for ( size_t i = 0; i < bucket_count(); ++i )
372 m_Buckets[i].clear();
373 m_ItemCounter.reset();
376 /// Checks if the set is empty
378 @warning If you use \p atomicity::empty_item_counter in \p traits::item_counter,
379 the function always returns \p true.
386 /// Returns item count in the set
388 @warning If you use \p atomicity::empty_item_counter in \p traits::item_counter,
389 the function always returns 0.
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* b )
435 new (b) internal_bucket_type;
438 template <typename Stat>
439 typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type* b )
441 new (b) 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