cds/intrusive/details/michael_set_base.h

   1 //$$CDS-header$$
   2
   3 #ifndef CDSLIB_INTRUSIVE_DETAILS_MICHAEL_SET_BASE_H
   4 #define CDSLIB_INTRUSIVE_DETAILS_MICHAEL_SET_BASE_H
   5
   6 #include <cds/intrusive/details/base.h>
   7 #include <cds/opt/compare.h>
   8 #include <cds/opt/hash.h>
   9 #include <cds/algo/bitop.h>
  10 #include <cds/algo/atomic.h>
  11
  12 namespace cds { namespace intrusive {
  13
  14     /// MichaelHashSet related definitions
  15     /** @ingroup cds_intrusive_helper
  16     */
  17     namespace michael_set {
  18
  19         //@cond
  20         struct implementation_tag;
  21         //@endcond
  22
  23         /// MichaelHashSet traits
  24         struct traits {
  25             /// Hash function
  26             /**
  27                 Hash function converts the key fields of struct \p T stored in the hash-set
  28                 into value of type \p size_t called hash value that is an index of hash table.
  29
  30                 This is mandatory type and has no predefined one.
  31             */
  32             typedef opt::none hash;
  33
  34             /// Item counter
  35             /**
  36                 The item counting is an important part of \p MichaelHashSet algorithm:
  37                 the \p empty() member function depends on correct item counting.
  38                 Therefore, \p atomicity::empty_item_counter is not allowed as a type of the option.
  39
  40                 Default is \p atomicity::item_counter.
  41             */
  42             typedef cds::atomicity::item_counter item_counter;
  43
  44             /// Bucket table allocator
  45             /**
  46                 Allocator for bucket table. Default is \ref CDS_DEFAULT_ALLOCATOR
  47                 The allocator uses only in constructor for allocating bucket table
  48                 and in destructor for destroying bucket table
  49             */
  50             typedef CDS_DEFAULT_ALLOCATOR   allocator;
  51         };
  52
  53         /// Metafunction converting option list to traits struct
  54         /**
  55             Available \p Options:
  56             - \p opt::hash - mandatory option, specifies hash functor.
  57             - \p opt::item_counter - optional, specifies item counting policy. See \p traits::item_counter
  58                 for default type.
  59             - \p opt::allocator - optional, bucket table allocator. Default is \ref CDS_DEFAULT_ALLOCATOR.
  60         */
  61         template <typename... Options>
  62         struct make_traits {
  63             typedef typename cds::opt::make_options< traits, Options...>::type type;   ///< Metafunction result
  64         };
  65
  66         //@cond
  67         namespace details {
  68             static inline size_t init_hash_bitmask( size_t nMaxItemCount, size_t nLoadFactor )
  69             {
  70                 if ( nLoadFactor == 0 )
  71                     nLoadFactor = 1;
  72                 if ( nMaxItemCount == 0 )
  73                     nMaxItemCount = 4;
  74                 const size_t nBucketCount = (size_t)( nMaxItemCount / nLoadFactor );
  75                 const size_t nLog2 = cds::bitop::MSB( nBucketCount );
  76
  77                 return (( size_t( 1 << nLog2 ) < nBucketCount ? size_t( 1 << (nLog2 + 1) ) : size_t( 1 << nLog2 ))) - 1;
  78             }
  79
  80             template <typename OrderedList, bool IsConst>
  81             struct list_iterator_selector;
  82
  83             template <typename OrderedList>
  84             struct list_iterator_selector< OrderedList, false>
  85             {
  86                 typedef OrderedList * bucket_ptr;
  87                 typedef typename OrderedList::iterator  type;
  88             };
  89
  90             template <typename OrderedList>
  91             struct list_iterator_selector< OrderedList, true>
  92             {
  93                 typedef OrderedList const * bucket_ptr;
  94                 typedef typename OrderedList::const_iterator  type;
  95             };
  96
  97             template <typename OrderedList, bool IsConst>
  98             class iterator
  99             {
 100                 friend class iterator < OrderedList, !IsConst >;
 101             protected:
 102                 typedef OrderedList bucket_type;
 103                 typedef typename list_iterator_selector< bucket_type, IsConst>::bucket_ptr bucket_ptr;
 104                 typedef typename list_iterator_selector< bucket_type, IsConst>::type list_iterator;
 105
 106                 bucket_ptr      m_pCurBucket;
 107                 list_iterator   m_itList;
 108                 bucket_ptr      m_pEndBucket;
 109
 110                 void next()
 111                 {
 112                     if ( m_pCurBucket < m_pEndBucket ) {
 113                         if ( ++m_itList != m_pCurBucket->end() )
 114                             return;
 115                         while ( ++m_pCurBucket < m_pEndBucket ) {
 116                             m_itList = m_pCurBucket->begin();
 117                             if ( m_itList != m_pCurBucket->end() )
 118                                 return;
 119                         }
 120                     }
 121                     m_pCurBucket = m_pEndBucket - 1;
 122                     m_itList = m_pCurBucket->end();
 123                 }
 124
 125             public:
 126                 typedef typename list_iterator::value_ptr   value_ptr;
 127                 typedef typename list_iterator::value_ref   value_ref;
 128
 129             public:
 130                 iterator()
 131                     : m_pCurBucket( nullptr )
 132                     , m_itList()
 133                     , m_pEndBucket( nullptr )
 134                 {}
 135
 136                 iterator( list_iterator const& it, bucket_ptr pFirst, bucket_ptr pLast )
 137                     : m_pCurBucket( pFirst )
 138                     , m_itList( it )
 139                     , m_pEndBucket( pLast )
 140                 {
 141                     if ( it == pFirst->end() )
 142                         next();
 143                 }
 144
 145                 iterator( iterator const& src )
 146                     : m_pCurBucket( src.m_pCurBucket )
 147                     , m_itList( src.m_itList )
 148                     , m_pEndBucket( src.m_pEndBucket )
 149                 {}
 150
 151                 value_ptr operator ->() const
 152                 {
 153                     assert( m_pCurBucket != nullptr );
 154                     return m_itList.operator ->();
 155                 }
 156
 157                 value_ref operator *() const
 158                 {
 159                     assert( m_pCurBucket != nullptr );
 160                     return m_itList.operator *();
 161                 }
 162
 163                 /// Pre-increment
 164                 iterator& operator ++()
 165                 {
 166                     next();
 167                     return *this;
 168                 }
 169
 170                 iterator& operator = (const iterator& src)
 171                 {
 172                     m_pCurBucket = src.m_pCurBucket;
 173                     m_pEndBucket = src.m_pEndBucket;
 174                     m_itList = src.m_itList;
 175                     return *this;
 176                 }
 177
 178                 bucket_ptr bucket() const
 179                 {
 180                     return m_pCurBucket != m_pEndBucket ? m_pCurBucket : nullptr;
 181                 }
 182
 183                 template <bool C>
 184                 bool operator ==(iterator<bucket_type, C> const& i) const
 185                 {
 186                     return m_pCurBucket == i.m_pCurBucket && m_itList == i.m_itList;
 187                 }
 188                 template <bool C>
 189                 bool operator !=(iterator<OrderedList, C> const& i ) const
 190                 {
 191                     return !( *this == i );
 192                 }
 193
 194             };
 195         }
 196         //@endcond
 197     } // namespace michael_set
 198
 199     //@cond
 200     // Forward declarations
 201     template <class GC, class OrderedList, class Traits = michael_set::traits>
 202     class MichaelHashSet;
 203     //@endcond
 204
 205 }} // namespace cds::intrusive
 206
 207 #endif // #ifndef CDSLIB_INTRUSIVE_DETAILS_MICHAEL_SET_BASE_H