2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
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 typedef typename ordered_list::stat stat; ///< Internal statistics
69 /// Hash functor for \ref value_type and all its derivatives that you use
70 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
71 typedef typename traits::item_counter item_counter; ///< Item counter type
72 typedef typename traits::allocator allocator; ///< Bucket table allocator
74 // GC and OrderedList::gc must be the same
75 static_assert(std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
77 // atomicity::empty_item_counter is not allowed as a item counter
78 static_assert(!std::is_same<item_counter, atomicity::empty_item_counter>::value,
79 "cds::atomicity::empty_item_counter is not allowed as a item counter");
83 typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat;
85 typedef typename ordered_list::template rebind_traits<
86 cds::opt::item_counter< cds::atomicity::empty_item_counter >
87 , cds::opt::stat< typename bucket_stat::wrapped_stat >
88 >::type internal_bucket_type_;
90 class internal_bucket_type: public internal_bucket_type_
92 typedef internal_bucket_type_ base_class;
94 using base_class::base_class;
95 using base_class::node_type;
96 using base_class::alloc_node;
97 using base_class::insert_node;
98 using base_class::node_to_value;
101 /// Bucket table allocator
102 typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator;
104 typedef typename internal_bucket_type::iterator bucket_iterator;
105 typedef typename internal_bucket_type::const_iterator bucket_const_iterator;
110 const size_t m_nHashBitmask;
111 item_counter m_ItemCounter; ///< Item counter
112 hash m_HashFunctor; ///< Hash functor
113 internal_bucket_type* m_Buckets; ///< bucket table
114 typename bucket_stat::stat m_Stat; ///< Internal statistics
118 ///@name Forward iterators
122 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
123 - it has no post-increment operator
124 - it iterates items in unordered fashion
126 The iterator interface:
130 // Default constructor
134 iterator( iterator const& src );
136 // Dereference operator
137 value_type * operator ->() const;
139 // Dereference operator
140 value_type& operator *() const;
142 // Preincrement operator
143 iterator& operator ++();
145 // Assignment operator
146 iterator& operator = (iterator const& src);
148 // Equality operators
149 bool operator ==(iterator const& i ) const;
150 bool operator !=(iterator const& i ) const;
154 typedef michael_set::details::iterator< internal_bucket_type, false > iterator;
156 /// Const forward iterator
158 For iterator's features and requirements see \ref iterator
160 typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator;
162 /// Returns a forward iterator addressing the first element in a set
164 For empty set \code begin() == end() \endcode
168 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
171 /// Returns an iterator that addresses the location succeeding the last element in a set
173 Do not use the value returned by <tt>end</tt> function to access any item.
174 The returned value can be used only to control reaching the end of the set.
175 For empty set \code begin() == end() \endcode
179 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
182 /// Returns a forward const iterator addressing the first element in a set
183 const_iterator begin() const
185 return get_const_begin();
188 /// Returns a forward const iterator addressing the first element in a set
189 const_iterator cbegin() const
191 return get_const_begin();
194 /// Returns an const iterator that addresses the location succeeding the last element in a set
195 const_iterator end() const
197 return get_const_end();
200 /// Returns an const iterator that addresses the location succeeding the last element in a set
201 const_iterator cend() const
203 return get_const_end();
208 /// Initialize hash set
210 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
211 when you create an object.
212 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
213 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
215 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
218 size_t nMaxItemCount, ///< estimation of max item count in the hash set
219 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
220 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
221 , m_Buckets( bucket_table_allocator().allocate( bucket_count() ) )
223 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
224 construct_bucket<bucket_stat>( it );
227 /// Clears hash set and destroys it
231 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
232 it->~internal_bucket_type();
233 bucket_table_allocator().deallocate( m_Buckets, bucket_count() );
238 The function inserts \p val in the set if it does not contain
239 an item with key equal to \p val.
241 Return an iterator pointing to inserted item if success, otherwise \ref end()
243 template <typename Q>
244 iterator insert( const Q& val )
246 internal_bucket_type& refBucket = bucket( val );
247 bucket_iterator it = refBucket.insert( val );
249 if ( it != refBucket.end() ) {
251 return iterator( it, &refBucket, m_Buckets + bucket_count() );
257 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
259 Return an iterator pointing to inserted item if success \ref end() otherwise
261 template <typename... Args>
262 iterator emplace( Args&&... args )
264 typename internal_bucket_type::node_type * pNode = internal_bucket_type::alloc_node( std::forward<Args>( args )... );
265 internal_bucket_type& refBucket = bucket( internal_bucket_type::node_to_value( *pNode ));
266 bucket_iterator it = refBucket.insert_node( pNode );
267 if ( it != refBucket.end() ) {
269 return iterator( it, &refBucket, m_Buckets + bucket_count() );
275 /// Updates the element
277 The operation performs inserting or changing data with lock-free manner.
279 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
281 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
282 item found or inserted, or \p end() if \p bAllowInsert is \p false,
284 \p second is true if new item has been added or \p false if the item is already in the set.
286 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
287 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
290 template <typename Q>
291 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
293 internal_bucket_type& refBucket = bucket( val );
294 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
296 if ( ret.first != refBucket.end() ) {
299 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
301 return std::make_pair( end(), ret.second );
304 template <typename Q>
305 CDS_DEPRECATED("ensure() is deprecated, use update()")
306 std::pair<iterator, bool> ensure( Q const& val )
308 return update( val, true );
312 /// Checks whether the set contains \p key
314 The function searches the item with key equal to \p key
315 and returns an iterator pointed to item found if the key is found,
316 or \ref end() otherwise.
318 Note the hash functor specified for class \p Traits template parameter
319 should accept a parameter of type \p Q that can be not the same as \p value_type.
321 template <typename Q>
322 iterator contains( Q const& key )
324 internal_bucket_type& refBucket = bucket( key );
325 bucket_iterator it = refBucket.contains( key );
326 if ( it != refBucket.end() )
327 return iterator( it, &refBucket, m_Buckets + bucket_count() );
332 template <typename Q>
333 CDS_DEPRECATED("use contains()")
334 iterator find( Q const& key )
336 return contains( key );
340 /// Checks whether the set contains \p key using \p pred predicate for searching
342 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
343 \p Less functor has the interface like \p std::less.
344 \p Less must imply the same element order as the comparator used for building the set.
346 template <typename Q, typename Less>
347 iterator contains( Q const& key, Less pred )
349 internal_bucket_type& refBucket = bucket( key );
350 bucket_iterator it = refBucket.contains( key, pred );
351 if ( it != refBucket.end() )
352 return iterator( it, &refBucket, m_Buckets + bucket_count() );
357 template <typename Q, typename Less>
358 CDS_DEPRECATED("use contains()")
359 iterator find_with( Q const& key, Less pred )
361 return contains( key, pred );
365 /// Clears the set (not atomic)
368 for ( size_t i = 0; i < bucket_count(); ++i )
369 m_Buckets[i].clear();
370 m_ItemCounter.reset();
373 /// Checks if the set is empty
375 The emptiness is checked by the item counting: if item count is zero then the set is empty.
376 Thus, the correct item counting feature is an important part of Michael's set implementation.
383 /// Returns item count in the set
386 return m_ItemCounter;
389 /// Returns const reference to internal statistics
390 stat const& statistics() const
395 /// Returns the size of hash table
397 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
398 the value returned is an constant depending on object initialization parameters;
399 see MichaelHashSet::MichaelHashSet for explanation.
401 size_t bucket_count() const
403 return m_nHashBitmask + 1;
408 /// Calculates hash value of \p key
409 template <typename Q>
410 size_t hash_value( const Q& key ) const
412 return m_HashFunctor( key ) & m_nHashBitmask;
415 /// Returns the bucket (ordered list) for \p key
416 template <typename Q>
417 internal_bucket_type& bucket( const Q& key )
419 return m_Buckets[hash_value( key )];
425 template <typename Stat>
426 typename std::enable_if< Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
428 new (bucket) internal_bucket_type;
431 template <typename Stat>
432 typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
434 new (bucket) internal_bucket_type( m_Stat );
437 const_iterator get_const_begin() const
439 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
441 const_iterator get_const_end() const
443 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
450 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H