3 #ifndef CDSLIB_CONTAINER_MICHAEL_MAP_NOGC_H
4 #define CDSLIB_CONTAINER_MICHAEL_MAP_NOGC_H
6 #include <cds/container/details/michael_map_base.h>
7 #include <cds/gc/nogc.h>
8 #include <cds/details/allocator.h>
10 namespace cds { namespace container {
12 /// Michael's hash map (template specialization for \p cds::gc::nogc)
13 /** @ingroup cds_nonintrusive_map
14 \anchor cds_nonintrusive_MichaelHashMap_nogc
16 This specialization is so-called append-only when no item
17 reclamation may be performed. The class does not support deleting of map item.
19 See @ref cds_nonintrusive_MichaelHashMap_hp "MichaelHashMap" for description of template parameters.
23 #ifdef CDS_DOXYGEN_INVOKED
24 class Traits = michael_map::traits
29 class MichaelHashMap<cds::gc::nogc, OrderedList, Traits>
32 typedef cds::gc::nogc gc; ///< No garbage collector
33 typedef OrderedList bucket_type; ///< type of ordered list used as a bucket implementation
34 typedef Traits traits; ///< Map traits
36 typedef typename bucket_type::key_type key_type; ///< key type
37 typedef typename bucket_type::mapped_type mapped_type; ///< type of value to be stored in the map
38 typedef typename bucket_type::value_type value_type; ///< Pair used as the some functor's argument
40 typedef typename bucket_type::key_comparator key_comparator; ///< key comparing functor
42 /// Hash functor for \ref key_type and all its derivatives that you use
43 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
44 typedef typename traits::item_counter item_counter; ///< Item counter type
46 /// Bucket table allocator
47 typedef cds::details::Allocator< bucket_type, typename traits::allocator > bucket_table_allocator;
50 typedef cds::container::michael_map::implementation_tag implementation_tag;
55 typedef typename bucket_type::iterator bucket_iterator;
56 typedef typename bucket_type::const_iterator bucket_const_iterator;
60 item_counter m_ItemCounter; ///< Item counter
61 hash m_HashFunctor; ///< Hash functor
62 bucket_type * m_Buckets; ///< bucket table
66 const size_t m_nHashBitmask;
71 /// Calculates hash value of \p key
72 size_t hash_value( key_type const & key ) const
74 return m_HashFunctor( key ) & m_nHashBitmask;
77 /// Returns the bucket (ordered list) for \p key
78 bucket_type& bucket( key_type const& key )
80 return m_Buckets[ hash_value( key ) ];
87 \p IsConst - constness boolean flag
89 The forward iterator for Michael's map is based on \p OrderedList forward iterator and has some features:
90 - it has no post-increment operator, only pre-increment
91 - it iterates items in unordered fashion
93 template <bool IsConst>
94 class iterator_type: private cds::intrusive::michael_set::details::iterator< bucket_type, IsConst >
97 typedef cds::intrusive::michael_set::details::iterator< bucket_type, IsConst > base_class;
98 friend class MichaelHashMap;
103 //typedef typename base_class::bucket_type bucket_type;
104 typedef typename base_class::bucket_ptr bucket_ptr;
105 typedef typename base_class::list_iterator list_iterator;
107 //typedef typename bucket_type::key_type key_type;
111 /// Value pointer type (const for const_iterator)
112 typedef typename cds::details::make_const_type<typename MichaelHashMap::mapped_type, IsConst>::pointer value_ptr;
113 /// Value reference type (const for const_iterator)
114 typedef typename cds::details::make_const_type<typename MichaelHashMap::mapped_type, IsConst>::reference value_ref;
116 /// Key-value pair pointer type (const for const_iterator)
117 typedef typename cds::details::make_const_type<typename MichaelHashMap::value_type, IsConst>::pointer pair_ptr;
118 /// Key-value pair reference type (const for const_iterator)
119 typedef typename cds::details::make_const_type<typename MichaelHashMap::value_type, IsConst>::reference pair_ref;
123 iterator_type( list_iterator const& it, bucket_ptr pFirst, bucket_ptr pLast )
124 : base_class( it, pFirst, pLast )
135 iterator_type( const iterator_type& src )
139 /// Dereference operator
140 pair_ptr operator ->() const
142 assert( base_class::m_pCurBucket != nullptr );
143 return base_class::m_itList.operator ->();
146 /// Dereference operator
147 pair_ref operator *() const
149 assert( base_class::m_pCurBucket != nullptr );
150 return base_class::m_itList.operator *();
154 iterator_type& operator ++()
156 base_class::operator++();
160 /// Assignment operator
161 iterator_type& operator = (const iterator_type& src)
163 base_class::operator =(src);
167 /// Returns current bucket (debug function)
168 bucket_ptr bucket() const
170 return base_class::bucket();
173 /// Equality operator
175 bool operator ==(iterator_type<C> const& i ) const
177 return base_class::operator ==( i );
179 /// Equality operator
181 bool operator !=(iterator_type<C> const& i ) const
183 return !( *this == i );
190 typedef iterator_type< false > iterator;
192 /// Const forward iterator
193 typedef iterator_type< true > const_iterator;
195 /// Returns a forward iterator addressing the first element in a set
197 For empty set \code begin() == end() \endcode
201 return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
204 /// Returns an iterator that addresses the location succeeding the last element in a set
206 Do not use the value returned by <tt>end</tt> function to access any item.
207 The returned value can be used only to control reaching the end of the set.
208 For empty set \code begin() == end() \endcode
212 return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
215 /// Returns a forward const iterator addressing the first element in a set
217 const_iterator begin() const
219 return get_const_begin();
221 const_iterator cbegin() const
223 return get_const_begin();
227 /// Returns an const iterator that addresses the location succeeding the last element in a set
229 const_iterator end() const
231 return get_const_end();
233 const_iterator cend() const
235 return get_const_end();
241 const_iterator get_const_begin() const
243 return const_iterator( const_cast<bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
245 const_iterator get_const_end() const
247 return const_iterator( const_cast<bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
252 /// Initialize the map
254 The Michael's hash map is non-expandable container. You should point the average count of items \p nMaxItemCount
255 when you create an object.
256 \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
257 Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
258 Note, that many popular STL hash map implementation uses load factor 1.
260 The ctor defines hash table size as rounding <tt>nMacItemCount / nLoadFactor</tt> up to nearest power of two.
263 size_t nMaxItemCount, ///< estimation of max item count in the hash set
264 size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
265 ) : m_nHashBitmask( michael_map::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
267 // GC and OrderedList::gc must be the same
268 static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
270 // atomicity::empty_item_counter is not allowed as a item counter
271 static_assert( !std::is_same<item_counter, atomicity::empty_item_counter>::value,
272 "cds::atomicity::empty_item_counter is not allowed as a item counter");
274 m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
277 /// Clears hash set and destroys it
281 bucket_table_allocator().Delete( m_Buckets, bucket_count() );
284 /// Inserts new node with key and default value
286 The function creates a node with \p key and default value, and then inserts the node created into the map.
289 - The \ref key_type should be constructible from value of type \p K.
290 In trivial case, \p K is equal to \ref key_type.
291 - The \ref mapped_type should be default-constructible.
293 Returns an iterator pointed to inserted value, or \p end() if inserting is failed
295 template <typename K>
296 iterator insert( const K& key )
298 bucket_type& refBucket = bucket( key );
299 bucket_iterator it = refBucket.insert( key );
301 if ( it != refBucket.end() ) {
303 return iterator( it, &refBucket, m_Buckets + bucket_count() );
311 The function creates a node with copy of \p val value
312 and then inserts the node created into the map.
315 - The \ref key_type should be constructible from \p key of type \p K.
316 - The \ref mapped_type should be constructible from \p val of type \p V.
318 Returns an iterator pointed to inserted value, or \p end() if inserting is failed
320 template <typename K, typename V>
321 iterator insert( K const& key, V const& val )
323 bucket_type& refBucket = bucket( key );
324 bucket_iterator it = refBucket.insert( key, val );
326 if ( it != refBucket.end() ) {
328 return iterator( it, &refBucket, m_Buckets + bucket_count() );
334 /// Inserts new node and initialize it by a functor
336 This function inserts new node with key \p key and if inserting is successful then it calls
337 \p func functor with signature
340 void operator()( value_type& item );
344 The argument \p item of user-defined functor \p func is the reference
345 to the map's item inserted. <tt>item.second</tt> is a reference to item's value that may be changed.
347 The user-defined functor it is called only if the inserting is successful.
348 The \p key_type should be constructible from value of type \p K.
350 The function allows to split creating of new item into two part:
351 - create item from \p key;
352 - insert new item into the map;
353 - if inserting is successful, initialize the value of item by calling \p f functor
355 This can be useful if complete initialization of object of \p mapped_type is heavyweight and
356 it is preferable that the initialization should be completed only if inserting is successful.
358 Returns an iterator pointed to inserted value, or \p end() if inserting is failed
360 @warning For \ref cds_nonintrusive_MichaelKVList_nogc "MichaelKVList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
361 \ref cds_nonintrusive_LazyKVList_nogc "LazyKVList" provides exclusive access to inserted item and does not require any node-level
364 template <typename K, typename Func>
365 iterator insert_with( const K& key, Func func )
367 bucket_type& refBucket = bucket( key );
368 bucket_iterator it = refBucket.insert_with( key, func );
370 if ( it != refBucket.end() ) {
372 return iterator( it, &refBucket, m_Buckets + bucket_count() );
378 /// For key \p key inserts data of type \p mapped_type created from \p args
380 \p key_type should be constructible from type \p K
382 Returns an iterator pointed to inserted value, or \p end() if inserting is failed
384 template <typename K, typename... Args>
385 iterator emplace( K&& key, Args&&... args )
387 bucket_type& refBucket = bucket( key );
388 bucket_iterator it = refBucket.emplace( std::forward<K>(key), std::forward<Args>(args)... );
390 if ( it != refBucket.end() ) {
392 return iterator( it, &refBucket, m_Buckets + bucket_count() );
400 If \p key is not in the list and \p bAllowInsert is \p true,
401 the function inserts a new item.
402 Otherwise, the function returns an iterator pointing to the item found.
404 Returns <tt> std::pair<iterator, bool> </tt> where \p first is an iterator pointing to
405 item found or inserted, \p second is true if new item has been added or \p false if the item
406 already is in the list.
408 @warning For \ref cds_nonintrusive_MichaelKVList_nogc "MichaelKVList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
409 \ref cds_nonintrusive_LazyKVList_nogc "LazyKVList" provides exclusive access to inserted item and does not require any node-level
412 template <typename K>
413 std::pair<iterator, bool> update( const K& key, bool bAllowInsert = true )
415 bucket_type& refBucket = bucket( key );
416 std::pair<bucket_iterator, bool> ret = refBucket.update( key, bAllowInsert );
421 return std::make_pair( iterator( ret.first, &refBucket, m_Buckets + bucket_count() ), ret.second );
424 // Deprecated, use update()
425 template <typename K>
426 std::pair<iterator, bool> ensure( K const& key )
428 return update( key, true );
432 /// Checks whether the map contains \p key
434 The function searches the item with key equal to \p key
435 and returns an iterator pointed to item found and \ref end() otherwise
437 template <typename K>
438 iterator contains( K const& key )
440 bucket_type& refBucket = bucket( key );
441 bucket_iterator it = refBucket.contains( key );
443 if ( it != refBucket.end() )
444 return iterator( it, &refBucket, m_Buckets + bucket_count() );
449 // Deprecated, use contains()
450 template <typename K>
451 iterator find( K const& key )
453 return contains( key );
457 /// Checks whether the map contains \p key using \p pred predicate for searching
459 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
460 \p Less functor has the interface like \p std::less.
461 \p pred must imply the same element order as the comparator used for building the map.
463 template <typename K, typename Less>
464 iterator contains( K const& key, Less pred )
466 bucket_type& refBucket = bucket( key );
467 bucket_iterator it = refBucket.contains( key, pred );
469 if ( it != refBucket.end() )
470 return iterator( it, &refBucket, m_Buckets + bucket_count() );
475 // Deprecated, use contains()
476 template <typename K, typename Less>
477 iterator find_with( K const& key, Less pred )
479 return contains( key, pred );
483 /// Clears the map (not atomic)
486 for ( size_t i = 0; i < bucket_count(); ++i )
487 m_Buckets[i].clear();
488 m_ItemCounter.reset();
491 /// Checks whether the map is empty
493 Emptiness is checked by item counting: if item count is zero then the map is empty.
494 Thus, the correct item counting feature is an important part of Michael's map implementation.
501 /// Returns item count in the map
504 return m_ItemCounter;
507 /// Returns the size of hash table
509 Since \p %MichaelHashMap cannot dynamically extend the hash table size,
510 the value returned is an constant depending on object initialization parameters;
511 see \p MichaelHashMap::MichaelHashMap for explanation.
513 size_t bucket_count() const
515 return m_nHashBitmask + 1;
518 }} // namespace cds::container
520 #endif // ifndef CDSLIB_CONTAINER_MICHAEL_MAP_NOGC_H