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/
9 Redistribution and use in source and binary forms, with or without
10 modification, are permitted provided that the following conditions are met:
12 * Redistributions of source code must retain the above copyright notice, this
13 list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
16 this list of conditions and the following disclaimer in the documentation
17 and/or other materials provided with the distribution.
19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
23 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
26 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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
73 /// Bucket table allocator
74 typedef cds::details::Allocator< bucket_type, typename traits::allocator > bucket_table_allocator;
78 typedef typename bucket_type::iterator bucket_iterator;
79 typedef typename bucket_type::const_iterator bucket_const_iterator;
83 item_counter m_ItemCounter; ///< Item counter
84 hash m_HashFunctor; ///< Hash functor
85 bucket_type * m_Buckets; ///< bucket table
89 const size_t m_nHashBitmask;
94 /// Calculates hash value of \p key
96 size_t hash_value( const Q& key ) const
98 return m_HashFunctor( key ) & m_nHashBitmask;
101 /// Returns the bucket (ordered list) for \p key
102 template <typename Q>
103 bucket_type& bucket( const Q& key )
105 return m_Buckets[ hash_value( key ) ];
112 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
113 - it has no post-increment operator
114 - it iterates items in unordered fashion
116 typedef michael_set::details::iterator< bucket_type, false > iterator;
118 /// Const forward iterator
120 For iterator's features and requirements see \ref iterator
122 typedef michael_set::details::iterator< bucket_type, true > const_iterator;
124 /// Returns a forward iterator addressing the first element in a set
126 For empty set \code begin() == end() \endcode
130 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
133 /// Returns an iterator that addresses the location succeeding the last element in a set
135 Do not use the value returned by <tt>end</tt> function to access any item.
136 The returned value can be used only to control reaching the end of the set.
137 For empty set \code begin() == end() \endcode
141 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
144 /// Returns a forward const iterator addressing the first element in a set
146 const_iterator begin() const
148 return get_const_begin();
150 const_iterator cbegin() const
152 return get_const_begin();
156 /// Returns an const iterator that addresses the location succeeding the last element in a set
158 const_iterator end() const
160 return get_const_end();
162 const_iterator cend() const
164 return get_const_end();
170 const_iterator get_const_begin() const
172 return const_iterator( const_cast<bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
174 const_iterator get_const_end() const
176 return const_iterator( const_cast<bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
181 /// Initialize hash set
183 The Michael's hash set is non-expandable container. You should point the average count of items \p nMaxItemCount
184 when you create an object.
185 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
186 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
188 The ctor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
191 size_t nMaxItemCount, ///< estimation of max item count in the hash set
192 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
193 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
195 // GC and OrderedList::gc must be the same
196 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
198 // atomicity::empty_item_counter is not allowed as a item counter
199 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
200 "cds::atomicity::empty_item_counter is not allowed as a item counter");
202 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
205 /// Clears hash set and destroys it
209 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
214 The function inserts \p val in the set if it does not contain
215 an item with key equal to \p val.
217 Return an iterator pointing to inserted item if success, otherwise \ref end()
219 template <typename Q>
220 iterator insert( const Q& val )
222 bucket_type& refBucket = bucket( val );
223 bucket_iterator it = refBucket.insert( val );
225 if ( it != refBucket.end() ) {
227 return iterator( it, &refBucket, m_Buckets + bucket_count() );
233 /// Inserts data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
235 Return an iterator pointing to inserted item if success \ref end() otherwise
237 template <typename... Args>
238 iterator emplace( Args&&... args )
240 bucket_type& refBucket = bucket( value_type(std::forward<Args>(args)...));
241 bucket_iterator it = refBucket.emplace( std::forward<Args>(args)... );
243 if ( it != refBucket.end() ) {
245 return iterator( it, &refBucket, m_Buckets + bucket_count() );
251 /// Updates the element
253 The operation performs inserting or changing data with lock-free manner.
255 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
257 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
258 item found or inserted, or \p end() if \p bAllowInsert is \p false,
260 \p second is true if new item has been added or \p false if the item is already in the set.
262 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
263 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
266 template <typename Q>
267 std::pair<iterator, bool> update( Q const& val, bool bAllowInsert = true )
269 bucket_type& refBucket = bucket( val );
270 std::pair<bucket_iterator, bool> ret = refBucket.update( val, bAllowInsert );
272 if ( ret.first != refBucket.end() ) {
275 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
277 return std::make_pair( end(), ret.second );
280 template <typename Q>
281 CDS_DEPRECATED("ensure() is deprecated, use update()")
282 std::pair<iterator, bool> ensure( Q const& val )
284 return update( val, true );
288 /// Checks whether the set contains \p key
290 The function searches the item with key equal to \p key
291 and returns an iterator pointed to item found if the key is found,
292 or \ref end() otherwise.
294 Note the hash functor specified for class \p Traits template parameter
295 should accept a parameter of type \p Q that can be not the same as \p value_type.
297 template <typename Q>
298 iterator contains( Q const& key )
300 bucket_type& refBucket = bucket( key );
301 bucket_iterator it = refBucket.contains( key );
302 if ( it != refBucket.end() )
303 return iterator( it, &refBucket, m_Buckets + bucket_count() );
308 template <typename Q>
309 CDS_DEPRECATED("use contains()")
310 iterator find( Q const& key )
312 return contains( key );
316 /// Checks whether the set contains \p key using \p pred predicate for searching
318 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
319 \p Less functor has the interface like \p std::less.
320 \p Less must imply the same element order as the comparator used for building the set.
322 template <typename Q, typename Less>
323 iterator contains( Q const& key, Less pred )
325 bucket_type& refBucket = bucket( key );
326 bucket_iterator it = refBucket.contains( key, pred );
327 if ( it != refBucket.end() )
328 return iterator( it, &refBucket, m_Buckets + bucket_count() );
333 template <typename Q, typename Less>
334 CDS_DEPRECATED("use contains()")
335 iterator find_with( Q const& key, Less pred )
337 return contains( key, pred );
341 /// Clears the set (not atomic)
344 for ( size_t i = 0; i < bucket_count(); ++i )
345 m_Buckets[i].clear();
346 m_ItemCounter.reset();
349 /// Checks if the set is empty
351 The emptiness is checked by the item counting: if item count is zero then the set is empty.
352 Thus, the correct item counting feature is an important part of Michael's set implementation.
359 /// Returns item count in the set
362 return m_ItemCounter;
365 /// Returns the size of hash table
367 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
368 the value returned is an constant depending on object initialization parameters;
369 see MichaelHashSet::MichaelHashSet for explanation.
371 size_t bucket_count() const
373 return m_nHashBitmask + 1;
379 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_SET_NOGC_H