-//$$CDS-header$$
+/*
+ This file is a part of libcds - Concurrent Data Structures library
+
+ (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
+
+ 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:
+
+ * Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ 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.
+*/
#ifndef CDSLIB_CONTAINER_MICHAEL_MAP_RCU_H
#define 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;
+ 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
- /** @copydetails cds_nonintrusive_MichaelHashMap_hp_ctor
+ /**
+ The Michael's hash map is non-expandable container. You should point the average count of items \p nMaxItemCount
+ when you create an object.
+ \p nLoadFactor parameter defines average count of items per bucket and it should be small number between 1 and 10.
+ Remember, since the bucket implementation is an ordered list, searching in the bucket is linear [<tt>O(nLoadFactor)</tt>].
+ Note, that many popular STL hash map implementation uses load factor 1.
+
+ The ctor defines hash table size as rounding <tt>nMacItemCount / nLoadFactor</tt> up to nearest power of two.
*/
MichaelHashMap(
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
return bRet;
}
-
- /// Ensures that the \p key exists in the map
+ /// Updates data by \p key
/**
- The operation performs inserting or changing data with lock-free manner.
+ The operation performs inserting or replacing the element with lock-free manner.
If the \p key not found in the map, then the new item created from \p key
- is inserted into the map (note that in this case the \ref key_type should be
- constructible from type \p K).
- Otherwise, the functor \p func is called with item found.
- The functor \p Func may be a function with signature:
- \code
- void func( bool bNew, value_type& item );
- \endcode
- or a functor:
+ will be inserted into the map iff \p bAllowInsert is \p true.
+ (note that in this case the \ref key_type should be constructible from type \p K).
+ Otherwise, if \p key is found, the functor \p func is called with item found.
+
+ The functor \p Func signature is:
\code
struct my_functor {
void operator()( bool bNew, value_type& item );
};
\endcode
-
with arguments:
- \p bNew - \p true if the item has been inserted, \p false otherwise
- - \p item - item of the list
+ - \p item - the item found or inserted
- The functor may change any fields of the \p item.second that is \ref mapped_type.
+ The functor may change any fields of the \p item.second that is \p mapped_type.
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 is in the list.
+ already exists.
@warning For \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
\ref cds_nonintrusive_LazyKVList_rcu "LazyKVList" provides exclusive access to inserted item and does not require any node-level
synchronization.
*/
template <typename K, typename Func>
- std::pair<bool, bool> ensure( K const& key, Func func )
+ std::pair<bool, bool> update( K const& key, Func func, bool bAllowInsert = true )
{
- std::pair<bool, bool> bRet = bucket( key ).ensure( key, func );
- if ( bRet.first && bRet.second )
+ std::pair<bool, bool> bRet = bucket( key ).update( key, func, bAllowInsert );
+ if ( bRet.second )
++m_ItemCounter;
return bRet;
}
+ //@cond
+ template <typename K, typename Func>
+ CDS_DEPRECATED("ensure() is deprecated, use update()")
+ std::pair<bool, bool> ensure( K const& key, Func func )
+ {
+ return update( key, func, true );
+ }
+ //@endcond
/// For key \p key inserts data of type \p mapped_type created from \p args
/**
unlinks it from the map, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
If the item is not found the function return an empty \p exempt_ptr.
- @note The function does NOT call RCU read-side lock or synchronization,
- and does NOT dispose the item found. It just excludes the item from the map
- and returns a pointer to item found.
- You should lock RCU before calling of the function, and you should synchronize RCU
- outside the RCU lock to free extracted item
+ The function just excludes the key from the map and returns a pointer to item found.
+ 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.
\code
#include <cds/urcu/general_buffered.h>
// ...
rcu_michael_map::exempt_ptr p;
- {
- // first, we should lock RCU
- rcu_michael_map::rcu_lock lock;
-
- // Now, you can apply extract function
- // Note that you must not delete the item found inside the RCU lock
- p = theMap.extract( 10 );
- if ( p ) {
- // do something with p
- ...
- }
+
+ // For MichaelList we should not lock RCU
+
+ // Note that you must not delete the item found inside the RCU lock
+ p = theMap.extract( 10 );
+ if ( p ) {
+ // do something with p
+ ...
}
// We may safely release p here
/// Extracts an item from the map using \p pred predicate for searching
/**
- The function is an analog of \ref cds_nonintrusive_MichaelHashMap_rcu_extract "extract(exempt_ptr&, K const&)"
- but \p pred is used for key comparing.
+ The function is an analog of \p extract(K const&) but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the map.
*/
The function returns \p true if \p key is found, \p false otherwise.
*/
template <typename K, typename Func>
- bool find( K const& key, Func f ) const
+ bool find( K const& key, Func f )
{
return bucket( key ).find( key, f );
}
\p Less must imply the same element order as the comparator used for building the map.
*/
template <typename K, typename Less, typename Func>
- bool find_with( K const& key, Less pred, Func f ) const
+ bool find_with( K const& key, Less pred, Func f )
{
return bucket( key ).find_with( key, pred, f );
}
- /// Finds the key \p key
- /** \anchor cds_nonintrusive_MichaelMap_rcu_find_val
-
+ /// Checks whether the map contains \p key
+ /**
The function searches the item with key equal to \p key
and returns \p true if it is found, and \p false otherwise.
The function applies RCU lock internally.
*/
template <typename K>
- bool find( K const& key ) const
+ bool contains( K const& key )
{
- return bucket( key ).find( key );
+ return bucket( key ).contains( key );
}
+ //@cond
+ template <typename K>
+ CDS_DEPRECATED("deprecated, use contains()")
+ bool find( K const& key )
+ {
+ return bucket( key ).contains( key );
+ }
+ //@endcond
- /// Finds the key \p val using \p pred predicate for searching
+ /// Checks whether the map contains \p key using \p pred predicate for searching
/**
- The function is an analog of \ref cds_nonintrusive_MichaelMap_rcu_find_val "find(K const&)"
- but \p pred is used for key comparing.
+ The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p Less must imply the same element order as the comparator used for building the map.
*/
template <typename K, typename Less>
- bool find_with( K const& key, Less pred ) const
+ bool contains( K const& key, Less pred )
+ {
+ return bucket( key ).contains( key, pred );
+ }
+ //@cond
+ template <typename K, typename Less>
+ CDS_DEPRECATED("deprecated, use contains()")
+ bool find_with( K const& key, Less pred )
{
- return bucket( key ).find_with( key, pred );
+ return bucket( key ).contains( key, pred );
}
+ //@endcond
/// Finds \p key and return the item found
/** \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 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.
typedef cds::container::MichaelHashMap< your_template_parameters > hash_map;
hash_map theMap;
// ...
+ typename hash_map::raw_ptr gp;
{
// Lock RCU
hash_map::rcu_lock lock;
- hash_map::value_type * = theMap.get( 5 );
- if ( pVal ) {
- // Deal with pVal
+ gp = theMap.get( 5 );
+ if ( gp ) {
+ // Deal with gp
//...
}
// Unlock RCU by rcu_lock destructor
- // pVal can be freed at any time after RCU has been unlocked
+ // gp can be reclaimed at any time after RCU has been unlocked
}
\endcode
*/
template <typename K>
- value_type * get( K const& key ) const
+ raw_ptr get( K const& key )
{
return bucket( key ).get( key );
}
\p pred must imply the same element order as the comparator used for building the map.
*/
template <typename K, typename Less>
- value_type * get_with( K const& key, Less pred ) const
+ raw_ptr get_with( K const& key, Less pred )
{
return bucket( key ).get_with( key, pred );
}
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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