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/
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_INTRUSIVE_MICHAEL_SET_NOGC_H
32 #define CDSLIB_INTRUSIVE_MICHAEL_SET_NOGC_H
34 #include <cds/intrusive/details/michael_set_base.h>
35 #include <cds/gc/nogc.h>
37 namespace cds { namespace intrusive {
39 /// Michael's hash set (template specialization for gc::nogc)
40 /** @ingroup cds_intrusive_map
41 \anchor cds_intrusive_MichaelHashSet_nogc
43 This specialization is so-called append-only when no item
44 reclamation may be performed. The set does not support deleting of list item.
46 See \ref cds_intrusive_MichaelHashSet_hp "MichaelHashSet" for description of template parameters.
47 The template parameter \p OrderedList should be any \p cds::gc::nogc -derived ordered list, for example,
48 \ref cds_intrusive_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 used as a bucket implementation
63 typedef Traits traits; ///< Set traits
65 typedef typename ordered_list::value_type value_type; ///< type of value to be stored in the set
66 typedef typename ordered_list::key_comparator key_comparator; ///< key comparing functor
67 typedef typename ordered_list::disposer disposer; ///< Node disposer functor
68 #ifdef CDS_DOXYGEN_INVOKED
69 typedef typename ordered_list::stat stat; ///< Internal statistics
72 /// Hash functor for \p value_type and all its derivatives that you use
73 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
74 typedef typename traits::item_counter item_counter; ///< Item counter type
75 typedef typename traits::allocator allocator; ///< Bucket table allocator
77 // GC and OrderedList::gc must be the same
78 static_assert(std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
80 // atomicity::empty_item_counter is not allowed as a item counter
81 static_assert(!std::is_same<item_counter, atomicity::empty_item_counter>::value,
82 "atomicity::empty_item_counter is not allowed as a item counter");
86 typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat;
88 typedef typename ordered_list::template rebind_traits<
89 cds::opt::item_counter< cds::atomicity::empty_item_counter >
90 , cds::opt::stat< typename bucket_stat::wrapped_stat >
91 >::type internal_bucket_type;
93 typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator;
98 typedef typename bucket_stat::stat stat;
103 hash m_HashFunctor; ///< Hash functor
104 const size_t m_nHashBitmask;
105 internal_bucket_type * m_Buckets; ///< bucket table
106 item_counter m_ItemCounter; ///< Item counter
107 stat m_Stat; ///< Internal statistics
112 /// Calculates hash value of \p key
113 template <typename Q>
114 size_t hash_value( Q const & key ) const
116 return m_HashFunctor( key ) & m_nHashBitmask;
119 /// Returns the bucket (ordered list) for \p key
120 template <typename Q>
121 internal_bucket_type& bucket( Q const & key )
123 return m_Buckets[ hash_value( key ) ];
128 ///@name Forward iterators
132 The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features:
133 - it has no post-increment operator
134 - it iterates items in unordered fashion
136 The iterator interface:
140 // Default constructor
144 iterator( iterator const& src );
146 // Dereference operator
147 value_type * operator ->() const;
149 // Dereference operator
150 value_type& operator *() const;
152 // Preincrement operator
153 iterator& operator ++();
155 // Assignment operator
156 iterator& operator = (iterator const& src);
158 // Equality operators
159 bool operator ==(iterator const& i ) const;
160 bool operator !=(iterator const& i ) const;
164 typedef michael_set::details::iterator< internal_bucket_type, false > iterator;
166 /// Const forward iterator
168 For iterator's features and requirements see \ref iterator
170 typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator;
172 /// Returns a forward iterator addressing the first element in a set
174 For empty set \code begin() == end() \endcode
178 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count());
181 /// Returns an iterator that addresses the location succeeding the last element in a set
183 Do not use the value returned by <tt>end</tt> function to access any item.
184 The returned value can be used only to control reaching the end of the set.
185 For empty set \code begin() == end() \endcode
189 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
192 /// Returns a forward const iterator addressing the first element in a set
193 const_iterator begin() const
197 /// Returns a forward const iterator addressing the first element in a set
198 const_iterator cbegin() const
200 return const_iterator( m_Buckets[0].cbegin(), m_Buckets, m_Buckets + bucket_count());
203 /// Returns an const iterator that addresses the location succeeding the last element in a set
204 const_iterator end() const
208 /// Returns an const iterator that addresses the location succeeding the last element in a set
209 const_iterator cend() const
211 return const_iterator( m_Buckets[bucket_count() - 1].cend(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
216 /// Initializes hash set
218 The Michael's hash set is an unbounded container, but its hash table is non-expandable.
219 At construction time you should pass estimated maximum item count and a load factor.
220 The load factor is average size of one bucket - a small number between 1 and 10.
221 The bucket is an ordered single-linked list, searching in the bucket has linear complexity <tt>O(nLoadFactor)</tt>.
222 The constructor defines hash table size as rounding <tt>nMaxItemCount / nLoadFactor</tt> up to nearest power of two.
225 size_t nMaxItemCount, ///< estimation of max item count in the hash set
226 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
227 ) : m_nHashBitmask( michael_set::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
228 , m_Buckets( bucket_table_allocator().allocate( bucket_count()))
230 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
231 construct_bucket<bucket_stat>( it );
234 /// Clears hash set object and destroys it
239 for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
240 it->~internal_bucket_type();
241 bucket_table_allocator().deallocate( m_Buckets, bucket_count());
246 The function inserts \p val in the set if it does not contain
247 an item with key equal to \p val.
249 Returns \p true if \p val is placed into the set, \p false otherwise.
251 bool insert( value_type& val )
253 bool bRet = bucket( val ).insert( val );
259 /// Updates the element
261 The operation performs inserting or changing data with lock-free manner.
263 If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true.
264 Otherwise, the functor \p func is called with item found.
265 The functor signature is:
268 void operator()( bool bNew, value_type& item, value_type& val );
272 - \p bNew - \p true if the item has been inserted, \p false otherwise
273 - \p item - item of the set
274 - \p val - argument \p val passed into the \p %update() function
275 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
276 refers to the same thing.
278 The functor may change non-key fields of the \p item.
280 Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successful,
281 \p second is \p true if new item has been added or \p false if the item with \p key
282 already is in the set.
284 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
285 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
288 template <typename Func>
289 std::pair<bool, bool> update( value_type& val, Func func, bool bAllowInsert = true )
291 std::pair<bool, bool> bRet = bucket( val ).update( val, func, bAllowInsert );
297 template <typename Func>
298 CDS_DEPRECATED("ensure() is deprecated, use update()")
299 std::pair<bool, bool> ensure( value_type& val, Func func )
301 return update( val, func, true );
305 /// Checks whether the set contains \p key
308 The function searches the item with key equal to \p key
309 and returns the pointer to an element found or \p nullptr.
311 Note the hash functor specified for class \p Traits template parameter
312 should accept a parameter of type \p Q that can be not the same as \p value_type.
314 template <typename Q>
315 value_type * contains( Q const& key )
317 return bucket( key ).contains( key );
320 template <typename Q>
321 CDS_DEPRECATED("use contains()")
322 value_type * find( Q const& key )
324 return contains( key );
328 /// Checks whether the set contains \p key using \p pred predicate for searching
330 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
331 \p Less functor has the interface like \p std::less.
332 \p Less must imply the same element order as the comparator used for building the set.
334 template <typename Q, typename Less>
335 value_type * contains( Q const& key, Less pred )
337 return bucket( key ).contains( key, pred );
340 template <typename Q, typename Less>
341 CDS_DEPRECATED("use contains()")
342 value_type * find_with( Q const& key, Less pred )
344 return contains( key, pred );
348 /// Finds the key \p key
349 /** \anchor cds_intrusive_MichaelHashSet_nogc_find_func
350 The function searches the item with key equal to \p key and calls the functor \p f for item found.
351 The interface of \p Func functor is:
354 void operator()( value_type& item, Q& key );
357 where \p item is the item found, \p key is the <tt>find</tt> function argument.
359 The functor can change non-key fields of \p item.
360 The functor does not serialize simultaneous access to the set \p item. If such access is
361 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
363 The \p key argument is non-const since it can be used as \p f functor destination i.e., the functor
364 can modify both arguments.
366 Note the hash functor specified for class \p Traits template parameter
367 should accept a parameter of type \p Q that can be not the same as \p value_type.
369 The function returns \p true if \p key is found, \p false otherwise.
371 template <typename Q, typename Func>
372 bool find( Q& key, Func f )
374 return bucket( key ).find( key, f );
377 template <typename Q, typename Func>
378 bool find( Q const& key, Func f )
380 return bucket( key ).find( key, f );
384 /// Finds the key \p key using \p pred predicate for searching
386 The function is an analog of \ref cds_intrusive_MichaelHashSet_nogc_find_func "find(Q&, Func)"
387 but \p pred is used for key comparing.
388 \p Less functor has the interface like \p std::less.
389 \p pred must imply the same element order as the comparator used for building the set.
391 template <typename Q, typename Less, typename Func>
392 bool find_with( Q& key, Less pred, Func f )
394 return bucket( key ).find_with( key, pred, f );
397 template <typename Q, typename Less, typename Func>
398 bool find_with( Q const& key, Less pred, Func f )
400 return bucket( key ).find_with( key, pred, f );
404 /// Clears the set (non-atomic)
406 The function unlink all items from the set.
407 The function is not atomic. It cleans up each bucket and then resets the item counter to zero.
408 If there are a thread that performs insertion while \p %clear() is working the result is undefined in general case:
409 <tt> empty() </tt> may return \p true but the set may contain item(s).
410 Therefore, \p %clear() may be used only for debugging purposes.
412 For each item the \p disposer is called after unlinking.
416 for ( size_t i = 0; i < bucket_count(); ++i )
417 m_Buckets[i].clear();
418 m_ItemCounter.reset();
422 /// Checks if the set is empty
424 Emptiness is checked by item counting: if item count is zero then the set is empty.
425 Thus, the correct item counting feature is an important part of Michael's set implementation.
432 /// Returns item count in the set
435 return m_ItemCounter;
438 /// Returns the size of hash table
440 Since \p %MichaelHashSet cannot dynamically extend the hash table size,
441 the value returned is an constant depending on object initialization parameters;
442 see MichaelHashSet::MichaelHashSet for explanation.
444 size_t bucket_count() const
446 return m_nHashBitmask + 1;
449 /// Returns const reference to internal statistics
450 stat const& statistics() const
457 template <typename Stat>
458 typename std::enable_if< Stat::empty >::type construct_bucket( internal_bucket_type * bucket )
460 new (bucket) internal_bucket_type;
463 template <typename Stat>
464 typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type * bucket )
466 new (bucket) internal_bucket_type( m_Stat );
471 }} // namespace cds::intrusive
473 #endif // #ifndef CDSLIB_INTRUSIVE_MICHAEL_SET_NOGC_H