Source code repo: http://github.com/khizmax/libcds/
Download: http://sourceforge.net/projects/libcds/files/
-
+
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CDSLIB_CONTAINER_MICHAEL_MAP_RCU_H
\p key_type and an argument of template type \p K must meet the following requirements:
- \p key_type should be constructible from value of type \p K;
- the hash functor should be able to calculate correct hash value from argument \p key of type \p K:
- <tt> hash( key_type(key) ) == hash( key ) </tt>
+ <tt> hash( key_type(key)) == hash( key ) </tt>
- values of type \p key_type and \p K should be comparable
<b>How to use</b>
{
public:
typedef cds::urcu::gc< RCU > gc; ///< RCU used as garbage collector
- typedef OrderedList bucket_type; ///< type of ordered list used as a bucket implementation
+ typedef OrderedList ordered_list; ///< type of ordered list used as a bucket implementation
typedef Traits traits; ///< Map traits
- typedef typename bucket_type::key_type key_type ; ///< key type
- typedef typename bucket_type::mapped_type mapped_type ; ///< value type
- typedef typename bucket_type::value_type value_type ; ///< key/value pair stored in the list
- typedef typename bucket_type::key_comparator key_comparator ; ///< key comparison functor
+ typedef typename ordered_list::key_type key_type; ///< key type
+ typedef typename ordered_list::mapped_type mapped_type; ///< value type
+ typedef typename ordered_list::value_type value_type; ///< key/value pair stored in the list
+ typedef typename ordered_list::key_comparator key_comparator;///< key comparison functor
+#ifdef CDS_DOXYGEN_INVOKED
+ typedef typename ordered_list::stat stat; ///< Internal statistics
+ typedef typename ordered_list::exempt_ptr exempt_ptr; ///< pointer to extracted node
+ /// Type of \p get() member function return value
+ typedef typename ordered_list::raw_ptr raw_ptr;
+ typedef typename ordered_list::rcu_lock rcu_lock; ///< RCU scoped lock
+#endif
/// Hash functor for \ref key_type and all its derivatives that you use
typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
typedef typename traits::item_counter item_counter; ///< Item counter type
+ typedef typename traits::allocator allocator; ///< Bucket table allocator
- /// Bucket table allocator
- typedef cds::details::Allocator< bucket_type, typename traits::allocator > bucket_table_allocator;
-
- typedef typename bucket_type::rcu_lock rcu_lock; ///< RCU scoped lock
- typedef typename bucket_type::exempt_ptr exempt_ptr; ///< pointer to extracted node
/// Group of \p extract_xxx functions require external locking if underlying ordered list requires that
- static CDS_CONSTEXPR const bool c_bExtractLockExternal = bucket_type::c_bExtractLockExternal;
- /// Type of \p get() member function return value
- typedef typename bucket_type::raw_ptr raw_ptr;
+ static CDS_CONSTEXPR const bool c_bExtractLockExternal = ordered_list::c_bExtractLockExternal;
+
+ // GC and OrderedList::gc must be the same
+ static_assert(std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
+
+ // atomicity::empty_item_counter is not allowed as a item counter
+ static_assert(!std::is_same<item_counter, cds::atomicity::empty_item_counter>::value,
+ "cds::atomicity::empty_item_counter is not allowed as a item counter");
protected:
- item_counter m_ItemCounter; ///< Item counter
- hash m_HashFunctor; ///< Hash functor
- bucket_type * m_Buckets; ///< bucket table
+ //@cond
+ typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat;
- private:
+ typedef typename ordered_list::template rebind_traits<
+ cds::opt::item_counter< cds::atomicity::empty_item_counter >
+ , cds::opt::stat< typename bucket_stat::wrapped_stat >
+ >::type internal_bucket_type;
+
+ /// Bucket table allocator
+ typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator;
+ //@endcond
+
+ public:
//@cond
- const size_t m_nHashBitmask;
+ typedef typename bucket_stat::stat stat;
+ typedef typename internal_bucket_type::exempt_ptr exempt_ptr;
+ typedef typename internal_bucket_type::raw_ptr raw_ptr;
+ typedef typename internal_bucket_type::rcu_lock rcu_lock;
//@endcond
protected:
//@cond
- /// Calculates hash value of \p key
- template <typename Q>
- size_t hash_value( Q const& key ) const
- {
- return m_HashFunctor( key ) & m_nHashBitmask;
- }
-
- /// Returns the bucket (ordered list) for \p key
- template <typename Q>
- bucket_type& bucket( Q const& key )
- {
- return m_Buckets[ hash_value( key ) ];
- }
- template <typename Q>
- bucket_type const& bucket( Q const& key ) const
- {
- return m_Buckets[ hash_value( key ) ];
- }
+ const size_t m_nHashBitmask;
+ item_counter m_ItemCounter; ///< Item counter
+ hash m_HashFunctor; ///< Hash functor
+ internal_bucket_type * m_Buckets; ///< bucket table
+ stat m_Stat; ///< Internal statistics
//@endcond
- protected:
- /// Forward iterator
- /**
- \p IsConst - constness boolean flag
- The forward iterator for Michael's map is based on \p OrderedList forward iterator and has the following features:
- - it has no post-increment operator, only pre-increment
- - it iterates items in unordered fashion
- - The iterator cannot be moved across thread boundary since it may contain GC's guard that is thread-private GC data.
- - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
- deleting operations it is no guarantee that you iterate all item in the map.
-
- Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator for the concurrent container
- for debug purpose only.
- */
+ protected:
+ //@cond
template <bool IsConst>
- class iterator_type: private cds::intrusive::michael_set::details::iterator< bucket_type, IsConst >
+ class iterator_type: private cds::intrusive::michael_set::details::iterator< internal_bucket_type, IsConst >
{
- //@cond
- typedef cds::intrusive::michael_set::details::iterator< bucket_type, IsConst > base_class;
+ typedef cds::intrusive::michael_set::details::iterator< internal_bucket_type, IsConst > base_class;
friend class MichaelHashMap;
- //@endcond
protected:
- //@cond
- //typedef typename base_class::bucket_type bucket_type;
typedef typename base_class::bucket_ptr bucket_ptr;
typedef typename base_class::list_iterator list_iterator;
- //typedef typename bucket_type::key_type key_type;
- //@endcond
-
public:
/// Value pointer type (const for const_iterator)
typedef typename cds::details::make_const_type<typename MichaelHashMap::mapped_type, IsConst>::pointer value_ptr;
typedef typename cds::details::make_const_type<typename MichaelHashMap::value_type, IsConst>::reference pair_ref;
protected:
- //@cond
iterator_type( list_iterator const& it, bucket_ptr pFirst, bucket_ptr pLast )
: base_class( it, pFirst, pLast )
{}
- //@endcond
public:
/// Default ctor
return !( *this == i );
}
};
+ //@endcond
public:
+ ///@name Forward iterators (thread-safe under RCU lock)
+ //@{
+
/// Forward iterator
+ /**
+ The forward iterator for Michael's map is based on \p OrderedList forward iterator and has some features:
+ - it has no post-increment operator
+ - it iterates items in unordered fashion
+
+ You may safely use iterators in multi-threaded environment only under RCU lock.
+ Otherwise, a crash is possible if another thread deletes the element the iterator points to.
+
+ The iterator interface:
+ \code
+ class iterator {
+ public:
+ // Default constructor
+ iterator();
+
+ // Copy construtor
+ iterator( iterator const& src );
+
+ // Dereference operator
+ value_type * operator ->() const;
+
+ // Dereference operator
+ value_type& operator *() const;
+
+ // Preincrement operator
+ iterator& operator ++();
+
+ // Assignment operator
+ iterator& operator = (iterator const& src);
+
+ // Equality operators
+ bool operator ==(iterator const& i ) const;
+ bool operator !=(iterator const& i ) const;
+ };
+ \endcode
+ */
typedef iterator_type< false > iterator;
/// Const forward iterator
*/
iterator begin()
{
- return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count() );
+ return iterator( m_Buckets[0].begin(), m_Buckets, m_Buckets + bucket_count());
}
/// Returns an iterator that addresses the location succeeding the last element in a map
*/
iterator end()
{
- return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
+ return iterator( m_Buckets[bucket_count() - 1].end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
}
/// Returns a forward const iterator addressing the first element in a map
- //@{
const_iterator begin() const
{
return get_const_begin();
}
+
+ /// Returns a forward const iterator addressing the first element in a map
const_iterator cbegin() const
{
return get_const_begin();
}
- //@}
/// Returns an const iterator that addresses the location succeeding the last element in a map
- //@{
const_iterator end() const
{
return get_const_end();
}
+
+ /// Returns an const iterator that addresses the location succeeding the last element in a map
const_iterator cend() const
{
return get_const_end();
}
- //@}
-
- private:
- //@cond
- const_iterator get_const_begin() const
- {
- return const_iterator( const_cast<bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() );
- }
- const_iterator get_const_end() const
- {
- return const_iterator( const_cast<bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() );
- }
- //@endcond
+ //@}
public:
/// Initializes the map
size_t nMaxItemCount, ///< estimation of max item count in the hash map
size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket
) : m_nHashBitmask( michael_map::details::init_hash_bitmask( nMaxItemCount, nLoadFactor ))
+ , m_Buckets( bucket_table_allocator().allocate( bucket_count()))
{
- // GC and OrderedList::gc must be the same
- static_assert( std::is_same<gc, typename bucket_type::gc>::value, "GC and OrderedList::gc must be the same");
-
- // atomicity::empty_item_counter is not allowed as a item counter
- static_assert( !std::is_same<item_counter, cds::atomicity::empty_item_counter>::value,
- "cds::atomicity::empty_item_counter is not allowed as a item counter");
-
- m_Buckets = bucket_table_allocator().NewArray( bucket_count() );
+ for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
+ construct_bucket<bucket_stat>( it );
}
/// Clears hash map and destroys it
~MichaelHashMap()
{
clear();
- bucket_table_allocator().Delete( m_Buckets, bucket_count() );
+ for ( auto it = m_Buckets, itEnd = m_Buckets + bucket_count(); it != itEnd; ++it )
+ it->~internal_bucket_type();
+ bucket_table_allocator().deallocate( m_Buckets, bucket_count());
}
/// Inserts new node with key and default value
The function applies RCU lock internally.
- Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
+ Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
\p second is true if new item has been added or \p false if the item with \p key
already exists.
If the item is not found the function return an empty \p exempt_ptr.
The function just excludes the key from the map and returns a pointer to item found.
- Depends on \p bucket_type you should or should not lock RCU before calling of this function:
+ Depends on \p ordered_list you should or should not lock RCU before calling of this function:
- for the set based on \ref cds_nonintrusive_MichaelList_rcu "MichaelList" RCU should not be locked
- for the set based on \ref cds_nonintrusive_LazyList_rcu "LazyList" RCU should be locked
See ordered list implementation for details.
/** \anchor cds_nonintrusive_MichaelHashMap_rcu_get
The function searches the item with key equal to \p key and returns the pointer to item found.
If \p key is not found it returns \p nullptr.
- Note the type of returned value depends on underlying \p bucket_type.
+ Note the type of returned value depends on underlying \p ordered_list.
For details, see documentation of ordered list you use.
Note the compare functor should accept a parameter of type \p K that can be not the same as \p key_type.
return m_ItemCounter;
}
+ /// Returns const reference to internal statistics
+ stat const& statistics() const
+ {
+ return m_Stat;
+ }
+
/// Returns the size of hash table
/**
Since \p %MichaelHashMap cannot dynamically extend the hash table size,
{
return m_nHashBitmask + 1;
}
+
+ protected:
+ //@cond
+ /// Calculates hash value of \p key
+ template <typename Q>
+ size_t hash_value( Q const& key ) const
+ {
+ return m_HashFunctor( key ) & m_nHashBitmask;
+ }
+
+ /// Returns the bucket (ordered list) for \p key
+ template <typename Q>
+ internal_bucket_type& bucket( Q const& key )
+ {
+ return m_Buckets[hash_value( key )];
+ }
+ template <typename Q>
+ internal_bucket_type const& bucket( Q const& key ) const
+ {
+ return m_Buckets[hash_value( key )];
+ }
+ //@endcond
+ private:
+ //@cond
+ const_iterator get_const_begin() const
+ {
+ return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count());
+ }
+ const_iterator get_const_end() const
+ {
+ return const_iterator( const_cast<internal_bucket_type const&>(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count());
+ }
+
+ template <typename Stat>
+ typename std::enable_if< Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
+ {
+ new (bucket) internal_bucket_type;
+ }
+
+ template <typename Stat>
+ typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type* bucket )
+ {
+ new (bucket) internal_bucket_type( m_Stat );
+ }
+ //@endcond
};
}} // namespace cds::container
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