X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=cds%2Fcontainer%2Fmichael_set_rcu.h;h=54cf0686157ac4b592fd99e2d419f9bf0e9165e4;hb=6924946ceeaae28bc227fe7c9d8e939963bb9d69;hp=027619993a86b52430f763771cab241941e1ba06;hpb=3b8c11d9d713f617ad055ab8006c4cb43f9dee50;p=libcds.git diff --git a/cds/container/michael_set_rcu.h b/cds/container/michael_set_rcu.h index 02761999..54cf0686 100644 --- a/cds/container/michael_set_rcu.h +++ b/cds/container/michael_set_rcu.h @@ -1,4 +1,32 @@ -//$$CDS-header$$ +/* + 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_SET_RCU_H #define CDSLIB_CONTAINER_MICHAEL_SET_RCU_H @@ -108,77 +136,109 @@ namespace cds { namespace container { { public: typedef cds::urcu::gc< RCU > gc; ///< RCU used as garbage collector - typedef OrderedList bucket_type; ///< type of ordered list to be used as a bucket implementation + typedef OrderedList ordered_list; ///< type of ordered list to be used as a bucket implementation typedef Traits traits; ///< Set traits - typedef typename bucket_type::value_type value_type; ///< type of value to be stored in the list - typedef typename bucket_type::key_comparator key_comparator; ///< key comparing functor + typedef typename ordered_list::value_type value_type; ///< type of value to be stored in the list + typedef typename ordered_list::key_comparator key_comparator; ///< key comparing 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 + typedef typename ordered_list::raw_ptr raw_ptr; ///< Return type of \p get() member function and its derivatives +#endif /// Hash functor for \ref value_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::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 - typedef typename bucket_type::get_result get_result; ///< Return type of \p get() member function and its derivatives + typedef typename ordered_list::rcu_lock rcu_lock; ///< RCU scoped lock /// 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; - //@cond - typedef cds::container::michael_set::implementation_tag implementation_tag; - //@endcond + // GC and OrderedList::gc must be the same + static_assert(std::is_same::value, "GC and OrderedList::gc must be the same"); - protected: - item_counter m_ItemCounter; ///< Item counter - hash m_HashFunctor; ///< Hash functor - bucket_type * m_Buckets; ///< bucket table - - private: //@cond - const size_t m_nHashBitmask; + typedef typename ordered_list::template select_stat_wrapper< typename ordered_list::stat > bucket_stat; + + 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_; + + class internal_bucket_type: public internal_bucket_type_ + { + typedef internal_bucket_type_ base_class; + public: + using base_class::base_class; + using typename base_class::node_type; + using base_class::alloc_node; + using base_class::insert_node; + using base_class::node_to_value; + }; + + typedef typename internal_bucket_type::exempt_ptr exempt_ptr; + typedef typename internal_bucket_type::raw_ptr raw_ptr; + typedef typename bucket_stat::stat stat; //@endcond protected: //@cond - /// Calculates hash value of \p key - template - size_t hash_value( Q const& key ) const - { - return m_HashFunctor( key ) & m_nHashBitmask; - } + /// Bucket table allocator + typedef typename allocator::template rebind< internal_bucket_type >::other bucket_table_allocator; - /// Returns the bucket (ordered list) for \p key - template - bucket_type& bucket( Q const& key ) - { - return m_Buckets[ hash_value( key ) ]; - } - template - bucket_type const& bucket( Q const& key ) const - { - return m_Buckets[ hash_value( key ) ]; - } + const size_t m_nHashBitmask; + hash m_HashFunctor; ///< Hash functor + internal_bucket_type* m_Buckets; ///< bucket table + item_counter m_ItemCounter; ///< Item counter + stat m_Stat; ///< Internal statistics //@endcond + public: + ///@name Forward iterators (thread-safe under RCU lock) + //@{ /// Forward iterator /** The forward iterator for Michael's set is based on \p OrderedList forward iterator and has some features: - it has no post-increment operator - 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 set. - Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator for the concurrent container - for debug purpose only. + 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 michael_set::details::iterator< bucket_type, false > iterator; + typedef michael_set::details::iterator< internal_bucket_type, false > iterator; /// Const forward iterator - typedef michael_set::details::iterator< bucket_type, true > const_iterator; + typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator; /// Returns a forward iterator addressing the first element in a set /** @@ -186,7 +246,7 @@ namespace cds { namespace container { */ 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 set @@ -197,69 +257,63 @@ namespace cds { namespace container { */ 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 set - //@{ const_iterator begin() const { return get_const_begin(); } + + /// Returns a forward const iterator addressing the first element in a set const_iterator cbegin() const { return get_const_begin(); } - //@} /// Returns an const iterator that addresses the location succeeding the last element in a set - //@{ const_iterator end() const { return get_const_end(); } + + /// Returns an const iterator that addresses the location succeeding the last element in a set const_iterator cend() const { return get_const_end(); } - //@} - - private: - //@cond - const_iterator get_const_begin() const - { - return const_iterator( const_cast(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count() ); - } - const_iterator get_const_end() const - { - return const_iterator( const_cast(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count() ); - } - //@endcond + //@} public: /// Initialize hash set - /** @copydetails cds_nonintrusive_MichaelHashSet_hp_ctor + /** + The Michael's hash set 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 [O(nLoadFactor)]. + + The ctor defines hash table size as rounding nMaxItemCount / nLoadFactor up to nearest power of two. */ MichaelHashSet( size_t nMaxItemCount, ///< estimation of max item count in the hash set size_t nLoadFactor ///< load factor: estimation of max number of items in the bucket ) : m_nHashBitmask( michael_set::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::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::value, - "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( it ); } /// Clears hash set and destroys it ~MichaelHashSet() { 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 @@ -276,9 +330,9 @@ namespace cds { namespace container { Returns \p true if \p val is inserted into the set, \p false otherwise. */ template - bool insert( Q const& val ) + bool insert( Q&& val ) { - const bool bRet = bucket( val ).insert( val ); + const bool bRet = bucket( val ).insert( std::forward( val )); if ( bRet ) ++m_ItemCounter; return bRet; @@ -305,52 +359,58 @@ namespace cds { namespace container { synchronization. */ template - bool insert( Q const& val, Func f ) + bool insert( Q&& val, Func f ) { - const bool bRet = bucket( val ).insert( val, f ); + const bool bRet = bucket( val ).insert( std::forward( val ), f ); if ( bRet ) ++m_ItemCounter; return bRet; } - /// Ensures that the item exists in the set + /// Updates the element /** The operation performs inserting or changing data with lock-free manner. - If the \p val key not found in the set, then the new item created from \p val - is inserted into the set. Otherwise, the functor \p func is called with the item found. - The functor \p Func signature is: + If the item \p val not found in the set, then \p val is inserted iff \p bAllowInsert is \p true. + Otherwise, the functor \p func is called with item found. + The functor signature is: \code - struct my_functor { - void operator()( bool bNew, value_type& item, const Q& val ); + struct functor { + void operator()( bool bNew, value_type& item, Q const& val ); }; \endcode - with arguments: - \p bNew - \p true if the item has been inserted, \p false otherwise - \p item - item of the set - - \p val - argument \p key passed into the \p ensure function + - \p val - argument \p val passed into the \p %update() function The functor may change non-key fields of the \p item. The function applies RCU lock internally. - Returns std::pair where \p first is true if operation is successfull, - \p second is true if new item has been added or \p false if the item with \p key + Returns std::pair where \p first is \p true if operation is successful, + \p second is \p true if new item has been added or \p false if the item with \p key already is in the set. - @warning For \ref cds_nonintrusive_MichaelList_rcu "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting". - \ref cds_nonintrusive_LazyList_rcu "LazyList" provides exclusive access to inserted item and does not require any node-level + @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting". + \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level synchronization. */ template - std::pair ensure( const Q& val, Func func ) + std::pair update( Q const& val, Func func, bool bAllowInsert = true ) { - std::pair bRet = bucket( val ).ensure( val, func ); - if ( bRet.first && bRet.second ) + std::pair bRet = bucket( val ).update( val, func, bAllowInsert ); + if ( bRet.second ) ++m_ItemCounter; return bRet; + }//@cond + template + CDS_DEPRECATED("ensure() is deprecated, use update()") + std::pair ensure( const Q& val, Func func ) + { + return update( val, func, true ); } + //@endcond /// Inserts data of type \p value_type created from \p args /** @@ -361,7 +421,8 @@ namespace cds { namespace container { template bool emplace( Args&&... args ) { - bool bRet = bucket( value_type(std::forward(args)...) ).emplace( std::forward(args)... ); + typename internal_bucket_type::node_type * pNode = internal_bucket_type::alloc_node( std::forward( args )... ); + bool bRet = bucket( internal_bucket_type::node_to_value( *pNode )).insert_node( pNode ); if ( bRet ) ++m_ItemCounter; return bRet; @@ -458,7 +519,7 @@ namespace cds { namespace container { If the item with the key equal to \p key is not found the function return an empty \p exempt_ptr. The function just excludes the item from the set 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. @@ -575,39 +636,54 @@ namespace cds { namespace container { } //@endcond - /// Finds the key \p key - /** \anchor cds_nonintrusive_MichealSet_rcu_find_val + /// Checks whether the set 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. + and returns \p true if the key is found, and \p false otherwise. Note the hash functor specified for class \p Traits template parameter - should accept a parameter of type \p Q that may be not the same as \p value_type. + should accept a parameter of type \p Q that can be not the same as \p value_type. */ template - bool find( Q const & key ) + bool contains( Q const& key ) + { + return bucket( key ).contains( key ); + } + //@cond + template + CDS_DEPRECATED("use contains()") + bool find( Q const& key ) { - return bucket( key ).find( key ); + return contains( key ); } + //@endcond - /// Finds the key \p key using \p pred predicate for searching + /// Checks whether the set contains \p key using \p pred predicate for searching /** - The function is an analog of \ref cds_nonintrusive_MichealSet_rcu_find_val "find(Q const&)" - but \p pred is used for key comparing. + The function is an analog of contains( key ) 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 set. */ template - bool find_with( Q const & key, Less pred ) + bool contains( Q const& key, Less pred ) + { + return bucket( key ).contains( key, pred ); + } + //@cond + template + CDS_DEPRECATED("use contains()") + bool find_with( Q const& key, Less pred ) { - return bucket( key ).find_with( key, pred ); + return contains( key, pred ); } + //@endcond /// Finds the key \p key and return the item found /** \anchor cds_nonintrusive_MichaelHashSet_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 Q that can be not the same as \p value_type. @@ -617,7 +693,7 @@ namespace cds { namespace container { \code typedef cds::container::MichaelHashSet< your_template_parameters > hash_set; hash_set theSet; - typename hash_set::get_result gp; + typename hash_set::raw_ptr gp; // ... { // Lock RCU @@ -634,7 +710,7 @@ namespace cds { namespace container { \endcode */ template - get_result get( Q const& key ) + raw_ptr get( Q const& key ) { return bucket( key ).get( key ); } @@ -649,7 +725,7 @@ namespace cds { namespace container { \p pred must imply the same element order as the comparator used for building the set. */ template - get_result get_with( Q const& key, Less pred ) + raw_ptr get_with( Q const& key, Less pred ) { return bucket( key ).get_with( key, pred ); } @@ -664,8 +740,8 @@ namespace cds { namespace container { /// Checks if the set is empty /** - Emptiness is checked by item counting: if item count is zero then the set is empty. - Thus, the correct item counting feature is an important part of Michael's set implementation. + @warning If you use \p atomicity::empty_item_counter in \p traits::item_counter, + the function always returns \p true. */ bool empty() const { @@ -673,11 +749,21 @@ namespace cds { namespace container { } /// Returns item count in the set + /** + @warning If you use \p atomicity::empty_item_counter in \p traits::item_counter, + the function always returns 0. + */ size_t size() const { return m_ItemCounter; } + /// Returns const reference to internal statistics + stat const& statistics() const + { + return m_Stat; + } + /// Returns the size of hash table /** Since \p %MichaelHashSet cannot dynamically extend the hash table size, @@ -688,6 +774,49 @@ namespace cds { namespace container { { return m_nHashBitmask + 1; } + + protected: + //@cond + /// Calculates hash value of \p key + template + size_t hash_value( Q const& key ) const + { + return m_HashFunctor( key ) & m_nHashBitmask; + } + + /// Returns the bucket (ordered list) for \p key + template + internal_bucket_type& bucket( Q const& key ) + { + return m_Buckets[hash_value( key )]; + } + template + internal_bucket_type const& bucket( Q const& key ) const + { + return m_Buckets[hash_value( key )]; + } + + template + typename std::enable_if< Stat::empty >::type construct_bucket( internal_bucket_type* bkt ) + { + new (bkt) internal_bucket_type; + } + + template + typename std::enable_if< !Stat::empty >::type construct_bucket( internal_bucket_type* bkt ) + { + new (bkt) internal_bucket_type( m_Stat ); + } + + const_iterator get_const_begin() const + { + return const_iterator( const_cast(m_Buckets[0]).begin(), m_Buckets, m_Buckets + bucket_count()); + } + const_iterator get_const_end() const + { + return const_iterator( const_cast(m_Buckets[bucket_count() - 1]).end(), m_Buckets + bucket_count() - 1, m_Buckets + bucket_count()); + } + //@endcond }; }} // namespace cds::container