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>
36 #include <cds/details/allocator.h>
38 namespace cds { namespace container {
40 /// Michael's hash set (template specialization for gc::nogc)
41 /** @ingroup cds_nonintrusive_set
42 \anchor cds_nonintrusive_MichaelHashSet_nogc
44 This specialization is so-called append-only when no item
45 reclamation may be performed. The class does not support deleting of list item.
47 See \ref cds_nonintrusive_MichaelHashSet_hp "MichaelHashSet" for description of template parameters.
48 The template parameter \p OrderedList should be any \p gc::nogc -derived ordered list, for example,
49 \ref cds_nonintrusive_MichaelList_nogc "append-only MichaelList".
53 #ifdef CDS_DOXYGEN_INVOKED
54 class Traits = michael_set::traits
59 class MichaelHashSet< cds::gc::nogc, OrderedList, Traits >
62 typedef cds::gc::nogc gc; ///< Garbage collector
63 typedef OrderedList bucket_type; ///< type of ordered list to be used as a bucket implementation
64 typedef Traits traits; ///< Set traits
66 typedef typename bucket_type::value_type value_type; ///< type of value stored in the list
67 typedef typename bucket_type::key_comparator key_comparator; ///< key comparison functor
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
75 class internal_bucket_type: public bucket_type
77 typedef bucket_type base_class;
79 using base_class::node_type;
80 using base_class::alloc_node;
81 using base_class::insert_node;
82 using base_class::node_to_value;
85 /// Bucket table allocator
86 typedef cds::details::Allocator< internal_bucket_type, typename traits::allocator > bucket_table_allocator;
88 typedef typename bucket_type::iterator bucket_iterator;
89 typedef typename bucket_type::const_iterator bucket_const_iterator;
94 item_counter m_ItemCounter; ///< Item counter
95 hash m_HashFunctor; ///< Hash functor
96 internal_bucket_type * m_Buckets; ///< bucket table
101 const size_t m_nHashBitmask;
106 /// Calculates hash value of \p key
107 template <typename Q>
108 size_t hash_value( const Q& key ) const
110 return m_HashFunctor( key ) & m_nHashBitmask;
113 /// Returns the bucket (ordered list) for \p key
114 template <typename Q>
115 internal_bucket_type& bucket( const Q& key )
117 return m_Buckets[ hash_value( key ) ];
122 ///@name Forward iterators
126 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
127 - it has no post-increment operator
128 - it iterates items in unordered fashion
130 The iterator interface:
134 // Default constructor
138 iterator( iterator const& src );
140 // Dereference operator
141 value_type * operator ->() const;
143 // Dereference operator
144 value_type& operator *() const;
146 // Preincrement operator
147 iterator& operator ++();
149 // Assignment operator
150 iterator& operator = (iterator const& src);
152 // Equality operators
153 bool operator ==(iterator const& i ) const;
154 bool operator !=(iterator const& i ) const;
158 typedef michael_set::details::iterator< bucket_type, false > iterator;
160 /// Const forward iterator
162 For iterator's features and requirements see \ref iterator
164 typedef michael_set::details::iterator< bucket_type, true > const_iterator;
166 /// Returns a forward iterator addressing the first element in a set
168 For empty set \code begin() == end() \endcode
172 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
175 /// Returns an iterator that addresses the location succeeding the last element in a set
177 Do not use the value returned by <tt>end</tt> function to access any item.
178 The returned value can be used only to control reaching the end of the set.
179 For empty set \code begin() == end() \endcode
183 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
186 /// Returns a forward const iterator addressing the first element in a set
187 const_iterator begin() const
189 return get_const_begin();
192 /// Returns a forward const iterator addressing the first element in a set
193 const_iterator cbegin() const
195 return get_const_begin();
198 /// Returns an const iterator that addresses the location succeeding the last element in a set
199 const_iterator end() const
201 return get_const_end();
204 /// Returns an const iterator that addresses the location succeeding the last element in a set
205 const_iterator cend() const
207 return get_const_end();
213 const_iterator get_const_begin() const
215 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
217 const_iterator get_const_end() const
219 return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
224 /// Initialize hash set
226 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
227 when you create an object.
228 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
229 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
231 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
234 size_t nMaxItemCount, ///< estimation of max item count in the hash set
235 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
236 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
238 // GC and OrderedList::gc must be the same
239 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
241 // atomicity::empty_item_counter is not allowed as a item counter
242 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
243 "cds::atomicity::empty_item_counter is not allowed as a item counter");
245 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
248 /// Clears hash set and destroys it
252 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
257 The function inserts \p val in the set if it does not contain
258 an item with key equal to \p val.
260 Return an iterator pointing to inserted item if success, otherwise \ref end()
262 template <typename Q>
263 iterator insert( const Q& val )
265 internal_bucket_type& refBucket = bucket( val );
266 bucket_iterator it = refBucket.insert( val );
268 if ( it != refBucket.end() ) {
270 return iterator( it, &refBucket, m_Buckets + bucket_count() );
276 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
278 Return an iterator pointing to inserted item if success \ref end() otherwise
280 template <typename... Args>
281 iterator emplace( Args&&... args )
283 typename internal_bucket_type::node_type * pNode = internal_bucket_type::alloc_node( std::forward<Args>( args )... );
284 internal_bucket_type& refBucket = bucket( internal_bucket_type::node_to_value( *pNode ));
285 bucket_iterator it = refBucket.insert_node( pNode );
286 if ( it != refBucket.end() ) {
288 return iterator( it, &refBucket, m_Buckets + bucket_count() );
294 /// Updates the element
296 The operation performs inserting or changing data with lock-free manner.
298 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
300 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
301 item found or inserted, or \p end() if \p bAllowInsert is \p false,
303 \p second is true if new item has been added or \p false if the item is already in the set.
305 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
306 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
309 template <typename Q>
310 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
312 internal_bucket_type& refBucket = bucket( val );
313 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
315 if ( ret.first != refBucket.end() ) {
318 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
320 return std::make_pair( end(), ret.second );
323 template <typename Q>
324 CDS_DEPRECATED("ensure() is deprecated, use update()")
325 std::pair<iterator, bool> ensure( Q const& val )
327 return update( val, true );
331 /// Checks whether the set contains \p key
333 The function searches the item with key equal to \p key
334 and returns an iterator pointed to item found if the key is found,
335 or \ref end() otherwise.
337 Note the hash functor specified for class \p Traits template parameter
338 should accept a parameter of type \p Q that can be not the same as \p value_type.
340 template <typename Q>
341 iterator contains( Q const& key )
343 internal_bucket_type& refBucket = bucket( key );
344 bucket_iterator it = refBucket.contains( key );
345 if ( it != refBucket.end() )
346 return iterator( it, &refBucket, m_Buckets + bucket_count() );
351 template <typename Q>
352 CDS_DEPRECATED("use contains()")
353 iterator find( Q const& key )
355 return contains( key );
359 /// Checks whether the set contains \p key using \p pred predicate for searching
361 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
362 \p Less functor has the interface like \p std::less.
363 \p Less must imply the same element order as the comparator used for building the set.
365 template <typename Q, typename Less>
366 iterator contains( Q const& key, Less pred )
368 internal_bucket_type& refBucket = bucket( key );
369 bucket_iterator it = refBucket.contains( key, pred );
370 if ( it != refBucket.end() )
371 return iterator( it, &refBucket, m_Buckets + bucket_count() );
376 template <typename Q, typename Less>
377 CDS_DEPRECATED("use contains()")
378 iterator find_with( Q const& key, Less pred )
380 return contains( key, pred );
384 /// Clears the set (not atomic)
387 for ( size_t i = 0; i < bucket_count(); ++i )
388 m_Buckets[i].clear();
389 m_ItemCounter.reset();
392 /// Checks if the set is empty
394 The emptiness is checked by the item counting: if item count is zero then the set is empty.
395 Thus, the correct item counting feature is an important part of Michael's set implementation.
402 /// Returns item count in the set
405 return m_ItemCounter;
408 /// Returns the size of hash table
410 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
411 the value returned is an constant depending on object initialization parameters;
412 see MichaelHashSet::MichaelHashSet for explanation.
414 size_t bucket_count() const
416 return m_nHashBitmask + 1;
422 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H