From: khizmax Date: Sat, 27 Sep 2014 15:48:22 +0000 (+0400) Subject: Rename cds/intrusive/skip_list_impl.h to cds/intrusive/impl/skip_list.h X-Git-Tag: v2.0.0~274 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4871b0c7ea2bc42940428893922181245cd20fc1;p=libcds.git Rename cds/intrusive/skip_list_impl.h to cds/intrusive/impl/skip_list.h --- diff --git a/cds/intrusive/impl/skip_list.h b/cds/intrusive/impl/skip_list.h new file mode 100644 index 00000000..de43a010 --- /dev/null +++ b/cds/intrusive/impl/skip_list.h @@ -0,0 +1,1630 @@ +//$$CDS-header$$ + +#ifndef __CDS_INTRUSIVE_IMPL_SKIP_LIST_H +#define __CDS_INTRUSIVE_IMPL_SKIP_LIST_H + +#include +#include +#include +#include +#include +#include +#include + +namespace cds { namespace intrusive { + + //@cond + namespace skip_list { namespace details { + + template + class iterator { + public: + typedef GC gc; + typedef NodeTraits node_traits; + typedef BackOff back_off; + typedef typename node_traits::node_type node_type; + typedef typename node_traits::value_type value_type; + static bool const c_isConst = IsConst; + + typedef typename std::conditional< c_isConst, value_type const &, value_type &>::type value_ref; + + protected: + typedef typename node_type::marked_ptr marked_ptr; + typedef typename node_type::atomic_marked_ptr atomic_marked_ptr; + + typename gc::Guard m_guard; + node_type * m_pNode; + + protected: + static value_type * gc_protect( marked_ptr p ) + { + return node_traits::to_value_ptr( p.ptr() ); + } + + void next() + { + typename gc::Guard g; + g.copy( m_guard ); + back_off bkoff; + + for (;;) { + if ( m_pNode->next( m_pNode->height() - 1 ).load( atomics::memory_order_acquire ).bits() ) { + // Current node is marked as deleted. So, its next pointer can point to anything + // In this case we interrupt our iteration and returns end() iterator. + *this = iterator(); + return; + } + + marked_ptr p = m_guard.protect( (*m_pNode)[0], gc_protect ); + node_type * pp = p.ptr(); + if ( p.bits() ) { + // p is marked as deleted. Spin waiting for physical removal + bkoff(); + continue; + } + else if ( pp && pp->next( pp->height() - 1 ).load( atomics::memory_order_relaxed ).bits() ) { + // p is marked as deleted. Spin waiting for physical removal + bkoff(); + continue; + } + + m_pNode = pp; + break; + } + } + + public: // for internal use only!!! + iterator( node_type& refHead ) + : m_pNode( nullptr ) + { + back_off bkoff; + + for (;;) { + marked_ptr p = m_guard.protect( refHead[0], gc_protect ); + if ( !p.ptr() ) { + // empty skip-list + m_guard.clear(); + break; + } + + node_type * pp = p.ptr(); + // Logically deleted node is marked from highest level + if ( !pp->next( pp->height() - 1 ).load( atomics::memory_order_acquire ).bits() ) { + m_pNode = pp; + break; + } + + bkoff(); + } + } + + public: + iterator() + : m_pNode( nullptr ) + {} + + iterator( iterator const& s) + : m_pNode( s.m_pNode ) + { + m_guard.assign( node_traits::to_value_ptr(m_pNode) ); + } + + value_type * operator ->() const + { + assert( m_pNode != nullptr ); + assert( node_traits::to_value_ptr( m_pNode ) != nullptr ); + + return node_traits::to_value_ptr( m_pNode ); + } + + value_ref operator *() const + { + assert( m_pNode != nullptr ); + assert( node_traits::to_value_ptr( m_pNode ) != nullptr ); + + return *node_traits::to_value_ptr( m_pNode ); + } + + /// Pre-increment + iterator& operator ++() + { + next(); + return *this; + } + + iterator& operator = (const iterator& src) + { + m_pNode = src.m_pNode; + m_guard.copy( src.m_guard ); + return *this; + } + + template + bool operator ==(iterator const& i ) const + { + return m_pNode == i.m_pNode; + } + template + bool operator !=(iterator const& i ) const + { + return !( *this == i ); + } + }; + }} // namespace skip_list::details + //@endcond + + /// Lock-free skip-list set + /** @ingroup cds_intrusive_map + @anchor cds_intrusive_SkipListSet_hp + + The implementation of well-known probabilistic data structure called skip-list + invented by W.Pugh in his papers: + - [1989] W.Pugh Skip Lists: A Probabilistic Alternative to Balanced Trees + - [1990] W.Pugh A Skip List Cookbook + + A skip-list is a probabilistic data structure that provides expected logarithmic + time search without the need of rebalance. The skip-list is a collection of sorted + linked list. Nodes are ordered by key. Each node is linked into a subset of the lists. + Each list has a level, ranging from 0 to 32. The bottom-level list contains + all the nodes, and each higher-level list is a sublist of the lower-level lists. + Each node is created with a random top level (with a random height), and belongs + to all lists up to that level. The probability that a node has the height 1 is 1/2. + The probability that a node has the height N is 1/2 ** N (more precisely, + the distribution depends on an random generator provided, but our generators + have this property). + + The lock-free variant of skip-list is implemented according to book + - [2008] M.Herlihy, N.Shavit "The Art of Multiprocessor Programming", + chapter 14.4 "A Lock-Free Concurrent Skiplist". + \note The algorithm described in this book cannot be directly adapted for C++ (roughly speaking, + the algo contains a lot of bugs). The \b libcds implementation applies the approach discovered + by M.Michael in his \ref cds_intrusive_MichaelList_hp "lock-free linked list". + + Template arguments: + - \p GC - Garbage collector used. Note the \p GC must be the same as the GC used for item type \p T (see skip_list::node). + - \p T - type to be stored in the list. The type must be based on skip_list::node (for skip_list::base_hook) + or it must have a member of type skip_list::node (for skip_list::member_hook). + - \p Traits - type traits. See skip_list::type_traits for explanation. + + It is possible to declare option-based list with cds::intrusive::skip_list::make_traits metafunction istead of \p Traits template + argument. + Template argument list \p Options of cds::intrusive::skip_list::make_traits metafunction are: + - opt::hook - hook used. Possible values are: skip_list::base_hook, skip_list::member_hook, skip_list::traits_hook. + If the option is not specified, skip_list::base_hook<> and gc::HP is used. + - opt::compare - key comparison functor. No default functor is provided. + If the option is not specified, the opt::less is used. + - opt::less - specifies binary predicate used for key comparison. Default is \p std::less. + - opt::disposer - the functor used for dispose removed items. Default is opt::v::empty_disposer. Due the nature + of GC schema the disposer may be called asynchronously. + - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting. + - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default) + or opt::v::sequential_consistent (sequentially consisnent memory model). + - skip_list::random_level_generator - random level generator. Can be skip_list::xorshift, skip_list::turbo_pascal or + user-provided one. See skip_list::random_level_generator option description for explanation. + Default is \p %skip_list::turbo_pascal. + - opt::allocator - although the skip-list is an intrusive container, + an allocator should be provided to maintain variable randomly-calculated height of the node + since the node can contain up to 32 next pointers. The allocator option is used to allocate an array of next pointers + for nodes which height is more than 1. Default is \ref CDS_DEFAULT_ALLOCATOR. + - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::Default is used. + - opt::stat - internal statistics. Available types: skip_list::stat, skip_list::empty_stat (the default) + + \warning The skip-list requires up to 67 hazard pointers that may be critical for some GCs for which + the guard count is limited (like as gc::HP, gc::HRC). Those GCs should be explicitly initialized with + hazard pointer enough: \code cds::gc::HP myhp( 67 ) \endcode. Otherwise an run-time exception may be raised + when you try to create skip-list object. + + \note There are several specializations of \p %SkipListSet for each \p GC. You should include: + - for gc::HP garbage collector + - for gc::HRC garbage collector + - for gc::PTB garbage collector + - for \ref cds_intrusive_SkipListSet_nogc for persistent set + - for \ref cds_intrusive_SkipListSet_rcu "RCU type" + + Iterators + + The class supports a forward iterator (\ref iterator and \ref const_iterator). + The iteration is ordered. + The iterator object is thread-safe: the element pointed by the iterator object is guarded, + so, the element cannot be reclaimed while the iterator object is alive. + However, passing an iterator object between threads is dangerous. + + \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate + all elements in the set: any concurrent deletion can exclude the element + pointed by the iterator from the set, and your iteration can be terminated + before end of the set. Therefore, such iteration is more suitable for debugging purpose only + + Remember, each iterator object requires 2 additional hazard pointers, that may be + a limited resource for \p GC like as gc::HP and gc::HRC (for gc::PTB the count of + guards is unlimited). + + The iterator class supports the following minimalistic interface: + \code + struct iterator { + // Default ctor + iterator(); + + // Copy ctor + iterator( iterator const& s); + + value_type * operator ->() const; + value_type& operator *() const; + + // Pre-increment + iterator& operator ++(); + + // Copy assignment + iterator& operator = (const iterator& src); + + bool operator ==(iterator const& i ) const; + bool operator !=(iterator const& i ) const; + }; + \endcode + Note, the iterator object returned by \ref end, \p cend member functions points to \p nullptr and should not be dereferenced. + + How to use + + You should incorporate skip_list::node into your struct \p T and provide + appropriate skip_list::type_traits::hook in your \p Traits template parameters. Usually, for \p Traits you + define a struct based on skip_list::type_traits. + + Example for gc::HP and base hook: + \code + // Include GC-related skip-list specialization + #include + + // Data stored in skip list + struct my_data: public cds::intrusive::skip_list::node< cds::gc::HP > + { + // key field + std::string strKey; + + // other data + // ... + }; + + // my_data compare functor + struct my_data_cmp { + int operator()( const my_data& d1, const my_data& d2 ) + { + return d1.strKey.compare( d2.strKey ); + } + + int operator()( const my_data& d, const std::string& s ) + { + return d.strKey.compare(s); + } + + int operator()( const std::string& s, const my_data& d ) + { + return s.compare( d.strKey ); + } + }; + + + // Declare type_traits + struct my_traits: public cds::intrusive::skip_list::type_traits + { + typedef cds::intrusive::skip_list::base_hook< cds::opt::gc< cds::gc::HP > > hook; + typedef my_data_cmp compare; + }; + + // Declare skip-list set type + typedef cds::intrusive::SkipListSet< cds::gc::HP, my_data, my_traits > traits_based_set; + \endcode + + Equivalent option-based code: + \code + // GC-related specialization + #include + + struct my_data { + // see above + }; + struct compare { + // see above + }; + + // Declare option-based skip-list set + typedef cds::intrusive::SkipListSet< cds::gc::HP + ,my_data + , typename cds::intrusive::skip_list::make_traits< + cds::intrusive::opt::hook< cds::intrusive::skip_list::base_hook< cds::opt::gc< cds::gc::HP > > > + ,cds::intrusive::opt::compare< my_data_cmp > + >::type + > option_based_set; + + \endcode + */ + template < + class GC + ,typename T +#ifdef CDS_DOXYGEN_INVOKED + ,typename Traits = skip_list::type_traits +#else + ,typename Traits +#endif + > + class SkipListSet + { + public: + typedef T value_type ; ///< type of value stored in the skip-list + typedef Traits options ; ///< Traits template parameter + + typedef typename options::hook hook ; ///< hook type + typedef typename hook::node_type node_type ; ///< node type + +# ifdef CDS_DOXYGEN_INVOKED + typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter. +# else + typedef typename opt::details::make_comparator< value_type, options >::type key_comparator; +# endif + + typedef typename options::disposer disposer ; ///< disposer used + typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits + + typedef GC gc ; ///< Garbage collector + typedef typename options::item_counter item_counter ; ///< Item counting policy used + typedef typename options::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option + typedef typename options::random_level_generator random_level_generator ; ///< random level generator + typedef typename options::allocator allocator_type ; ///< allocator for maintaining array of next pointers of the node + typedef typename options::back_off back_off ; ///< Back-off strategy + typedef typename options::stat stat ; ///< internal statistics type + + public: + typedef cds::gc::guarded_ptr< gc, value_type > guarded_ptr; ///< Guarded pointer + + /// Max node height. The actual node height should be in range [0 .. c_nMaxHeight) + /** + The max height is specified by \ref skip_list::random_level_generator "random level generator" constant \p m_nUpperBound + but it should be no more than 32 (\ref skip_list::c_nHeightLimit). + */ + static unsigned int const c_nMaxHeight = std::conditional< + (random_level_generator::c_nUpperBound <= skip_list::c_nHeightLimit), + std::integral_constant< unsigned int, random_level_generator::c_nUpperBound >, + std::integral_constant< unsigned int, skip_list::c_nHeightLimit > + >::type::value; + + //@cond + static unsigned int const c_nMinHeight = 5; + //@endcond + + protected: + typedef typename node_type::atomic_marked_ptr atomic_node_ptr ; ///< Atomic marked node pointer + typedef typename node_type::marked_ptr marked_node_ptr ; ///< Node marked pointer + + protected: + //@cond + typedef skip_list::details::intrusive_node_builder< node_type, atomic_node_ptr, allocator_type > intrusive_node_builder; + + typedef typename std::conditional< + std::is_same< typename options::internal_node_builder, cds::opt::none >::value + ,intrusive_node_builder + ,typename options::internal_node_builder + >::type node_builder; + + typedef std::unique_ptr< node_type, typename node_builder::node_disposer > scoped_node_ptr; + + // c_nMaxHeight * 2 - pPred/pSucc guards + // + 1 - for erase, unlink + // + 1 - for clear + static size_t const c_nHazardPtrCount = c_nMaxHeight * 2 + 2; + struct position { + node_type * pPrev[ c_nMaxHeight ]; + node_type * pSucc[ c_nMaxHeight ]; + + typename gc::template GuardArray< c_nMaxHeight * 2 > guards ; ///< Guards array for pPrev/pSucc + + node_type * pCur ; // guarded by guards; needed only for *ensure* function + }; + //@endcond + + protected: + skip_list::details::head_node< node_type > m_Head ; ///< head tower (max height) + + item_counter m_ItemCounter ; ///< item counter + random_level_generator m_RandomLevelGen ; ///< random level generator instance + atomics::atomic m_nHeight ; ///< estimated high level + mutable stat m_Stat ; ///< internal statistics + + protected: + //@cond + unsigned int random_level() + { + // Random generator produces a number from range [0..31] + // We need a number from range [1..32] + return m_RandomLevelGen() + 1; + } + + template + node_type * build_node( Q v ) + { + return node_builder::make_tower( v, m_RandomLevelGen ); + } + + static value_type * gc_protect( marked_node_ptr p ) + { + return node_traits::to_value_ptr( p.ptr() ); + } + + static void dispose_node( value_type * pVal ) + { + assert( pVal != nullptr ); + typename node_builder::node_disposer()( node_traits::to_node_ptr(pVal) ); + disposer()( pVal ); + } + + template + bool find_position( Q const& val, position& pos, Compare cmp, bool bStopIfFound ) + { + node_type * pPred; + marked_node_ptr pSucc; + marked_node_ptr pCur; + + // Hazard pointer array: + // pPred: [nLevel * 2] + // pSucc: [nLevel * 2 + 1] + + retry: + pPred = m_Head.head(); + int nCmp = 1; + + for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { + pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); + while ( true ) { + pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); + if ( pCur.bits() ) { + // pCur.bits() means that pPred is logically deleted + goto retry; + } + + if ( pCur.ptr() == nullptr ) { + // end of the list at level nLevel - goto next level + break; + } + + // pSucc contains deletion mark for pCur + pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); + + if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) + goto retry; + + if ( pSucc.bits() ) { + // pCur is marked, i.e. logically deleted. + marked_node_ptr p( pCur.ptr() ); + if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), + memory_model::memory_order_release, atomics::memory_order_relaxed )) + { + if ( nLevel == 0 ) { + gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); + m_Stat.onEraseWhileFind(); + } + } + goto retry; + } + else { + nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr()), val ); + if ( nCmp < 0 ) { + pPred = pCur.ptr(); + pos.guards.copy( nLevel * 2, nLevel * 2 + 1 ) ; // pPrev guard := cur guard + } + else if ( nCmp == 0 && bStopIfFound ) + goto found; + else + break; + } + } + + // Next level + pos.pPrev[ nLevel ] = pPred; + pos.pSucc[ nLevel ] = pCur.ptr(); + } + + if ( nCmp != 0 ) + return false; + + found: + pos.pCur = pCur.ptr(); + return pCur.ptr() && nCmp == 0; + } + + bool find_min_position( position& pos ) + { + node_type * pPred; + marked_node_ptr pSucc; + marked_node_ptr pCur; + + // Hazard pointer array: + // pPred: [nLevel * 2] + // pSucc: [nLevel * 2 + 1] + + retry: + pPred = m_Head.head(); + + for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { + pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); + pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); + + // pCur.bits() means that pPred is logically deleted + // head cannot be deleted + assert( pCur.bits() == 0 ); + + if ( pCur.ptr() ) { + + // pSucc contains deletion mark for pCur + pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); + + if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) + goto retry; + + if ( pSucc.bits() ) { + // pCur is marked, i.e. logically deleted. + marked_node_ptr p( pCur.ptr() ); + if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), + memory_model::memory_order_release, atomics::memory_order_relaxed )) + { + if ( nLevel == 0 ) + gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); + } + goto retry; + } + } + + // Next level + pos.pPrev[ nLevel ] = pPred; + pos.pSucc[ nLevel ] = pCur.ptr(); + } + + return (pos.pCur = pCur.ptr()) != nullptr; + } + + bool find_max_position( position& pos ) + { + node_type * pPred; + marked_node_ptr pSucc; + marked_node_ptr pCur; + + // Hazard pointer array: + // pPred: [nLevel * 2] + // pSucc: [nLevel * 2 + 1] + + retry: + pPred = m_Head.head(); + + for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { + pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); + while ( true ) { + pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); + if ( pCur.bits() ) { + // pCur.bits() means that pPred is logically deleted + goto retry; + } + + if ( pCur.ptr() == nullptr ) { + // end of the list at level nLevel - goto next level + break; + } + + // pSucc contains deletion mark for pCur + pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); + + if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) + goto retry; + + if ( pSucc.bits() ) { + // pCur is marked, i.e. logically deleted. + marked_node_ptr p( pCur.ptr() ); + if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), + memory_model::memory_order_release, atomics::memory_order_relaxed )) + { + if ( nLevel == 0 ) + gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); + } + goto retry; + } + else { + if ( !pSucc.ptr() ) + break; + + pPred = pCur.ptr(); + pos.guards.copy( nLevel * 2, nLevel * 2 + 1 ); // pPrev guard := cur guard + //pos.guards.copy( nLevel * 2, gCur ) ; // pPrev guard := gCur + } + } + + // Next level + pos.pPrev[ nLevel ] = pPred; + pos.pSucc[ nLevel ] = pCur.ptr(); + } + + return (pos.pCur = pCur.ptr()) != nullptr; + } + + template + bool insert_at_position( value_type& val, node_type * pNode, position& pos, Func f ) + { + unsigned int nHeight = pNode->height(); + + for ( unsigned int nLevel = 1; nLevel < nHeight; ++nLevel ) + pNode->next(nLevel).store( marked_node_ptr(), memory_model::memory_order_relaxed ); + + { + marked_node_ptr p( pos.pSucc[0] ); + pNode->next( 0 ).store( p, memory_model::memory_order_release ); + if ( !pos.pPrev[0]->next(0).compare_exchange_strong( p, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed ) ) { + return false; + } + cds::unref( f )( val ); + } + + for ( unsigned int nLevel = 1; nLevel < nHeight; ++nLevel ) { + marked_node_ptr p; + while ( true ) { + marked_node_ptr q( pos.pSucc[ nLevel ]); + if ( !pNode->next( nLevel ).compare_exchange_strong( p, q, memory_model::memory_order_release, atomics::memory_order_relaxed )) { + // pNode has been marked as removed while we are inserting it + // Stop inserting + assert( p.bits() ); + m_Stat.onLogicDeleteWhileInsert(); + return true; + } + p = q; + if ( pos.pPrev[nLevel]->next(nLevel).compare_exchange_strong( q, marked_node_ptr( pNode ), memory_model::memory_order_release, atomics::memory_order_relaxed ) ) + break; + + // Renew insert position + m_Stat.onRenewInsertPosition(); + if ( !find_position( val, pos, key_comparator(), false )) { + // The node has been deleted while we are inserting it + m_Stat.onNotFoundWhileInsert(); + return true; + } + } + } + return true; + } + + template + bool try_remove_at( node_type * pDel, position& pos, Func f ) + { + assert( pDel != nullptr ); + + marked_node_ptr pSucc; + typename gc::Guard gSucc; + + // logical deletion (marking) + for ( unsigned int nLevel = pDel->height() - 1; nLevel > 0; --nLevel ) { + while ( true ) { + pSucc = gSucc.protect( pDel->next(nLevel), gc_protect ); + if ( pSucc.bits() || pDel->next(nLevel).compare_exchange_weak( pSucc, pSucc | 1, + memory_model::memory_order_acquire, atomics::memory_order_relaxed )) + { + break; + } + } + } + + while ( true ) { + pSucc = gSucc.protect( pDel->next(0), gc_protect ); + marked_node_ptr p( pSucc.ptr() ); + if ( pDel->next(0).compare_exchange_strong( p, marked_node_ptr(p.ptr(), 1), + memory_model::memory_order_acquire, atomics::memory_order_relaxed )) + { + cds::unref(f)( *node_traits::to_value_ptr( pDel )); + + // Physical deletion + // try fast erase + p = pDel; + for ( int nLevel = static_cast( pDel->height() - 1 ); nLevel >= 0; --nLevel ) { + pSucc = gSucc.protect( pDel->next(nLevel), gc_protect ); + if ( !pos.pPrev[nLevel]->next(nLevel).compare_exchange_strong( p, marked_node_ptr(pSucc.ptr()), + memory_model::memory_order_release, atomics::memory_order_relaxed) ) + { + // Make slow erase + find_position( *node_traits::to_value_ptr( pDel ), pos, key_comparator(), false ); + m_Stat.onSlowErase(); + return true; + } + } + + // Fast erasing success + gc::retire( node_traits::to_value_ptr( pDel ), dispose_node ); + m_Stat.onFastErase(); + return true; + } + else { + if ( p.bits() ) { + return false; + } + } + } + } + + enum finsd_fastpath_result { + find_fastpath_found, + find_fastpath_not_found, + find_fastpath_abort + }; + template + finsd_fastpath_result find_fastpath( Q& val, Compare cmp, Func f ) + { + node_type * pPred; + typename gc::template GuardArray<2> guards; + marked_node_ptr pCur; + marked_node_ptr pNull; + + back_off bkoff; + + pPred = m_Head.head(); + for ( int nLevel = static_cast( m_nHeight.load(memory_model::memory_order_relaxed) - 1 ); nLevel >= 0; --nLevel ) { + pCur = guards.protect( 1, pPred->next(nLevel), gc_protect ); + if ( pCur == pNull ) + continue; + + while ( pCur != pNull ) { + if ( pCur.bits() ) { + unsigned int nAttempt = 0; + while ( pCur.bits() && nAttempt++ < 16 ) { + bkoff(); + pCur = guards.protect( 1, pPred->next(nLevel), gc_protect ); + } + bkoff.reset(); + + if ( pCur.bits() ) { + // Maybe, we are on deleted node sequence + // Abort searching, try slow-path + return find_fastpath_abort; + } + } + + if ( pCur.ptr() ) { + int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr() ), val ); + if ( nCmp < 0 ) { + guards.copy( 0, 1 ); + pPred = pCur.ptr(); + pCur = guards.protect( 1, pCur->next(nLevel), gc_protect ); + } + else if ( nCmp == 0 ) { + // found + cds::unref(f)( *node_traits::to_value_ptr( pCur.ptr() ), val ); + return find_fastpath_found; + } + else // pCur > val - go down + break; + } + } + } + + return find_fastpath_not_found; + } + + template + bool find_slowpath( Q& val, Compare cmp, Func f ) + { + position pos; + if ( find_position( val, pos, cmp, true )) { + assert( cmp( *node_traits::to_value_ptr( pos.pCur ), val ) == 0 ); + + cds::unref(f)( *node_traits::to_value_ptr( pos.pCur ), val ); + return true; + } + else + return false; + } + + template + bool find_with_( Q& val, Compare cmp, Func f ) + { + switch ( find_fastpath( val, cmp, f )) { + case find_fastpath_found: + m_Stat.onFindFastSuccess(); + return true; + case find_fastpath_not_found: + m_Stat.onFindFastFailed(); + return false; + default: + break; + } + + if ( find_slowpath( val, cmp, f )) { + m_Stat.onFindSlowSuccess(); + return true; + } + + m_Stat.onFindSlowFailed(); + return false; + } + + template + bool get_with_( typename gc::Guard& guard, Q const& val, Compare cmp ) + { + return find_with_( val, cmp, [&guard](value_type& found, Q const& ) { guard.assign(&found); } ); + } + + template + bool erase_( Q const& val, Compare cmp, Func f ) + { + position pos; + + if ( !find_position( val, pos, cmp, false ) ) { + m_Stat.onEraseFailed(); + return false; + } + + node_type * pDel = pos.pCur; + typename gc::Guard gDel; + gDel.assign( node_traits::to_value_ptr(pDel) ); + assert( cmp( *node_traits::to_value_ptr( pDel ), val ) == 0 ); + + unsigned int nHeight = pDel->height(); + if ( try_remove_at( pDel, pos, f )) { + --m_ItemCounter; + m_Stat.onRemoveNode( nHeight ); + m_Stat.onEraseSuccess(); + return true; + } + + m_Stat.onEraseFailed(); + return false; + } + + template + bool extract_( typename gc::Guard& guard, Q const& val, Compare cmp ) + { + position pos; + + for (;;) { + if ( !find_position( val, pos, cmp, false ) ) { + m_Stat.onExtractFailed(); + return false; + } + + node_type * pDel = pos.pCur; + guard.assign( node_traits::to_value_ptr(pDel)); + assert( cmp( *node_traits::to_value_ptr( pDel ), val ) == 0 ); + + unsigned int nHeight = pDel->height(); + if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { + --m_ItemCounter; + m_Stat.onRemoveNode( nHeight ); + m_Stat.onExtractSuccess(); + return true; + } + + m_Stat.onExtractRetry(); + } + } + + bool extract_min_( typename gc::Guard& gDel ) + { + position pos; + + for (;;) { + if ( !find_min_position( pos ) ) { + // The list is empty + m_Stat.onExtractMinFailed(); + return false; + } + + node_type * pDel = pos.pCur; + + unsigned int nHeight = pDel->height(); + gDel.assign( node_traits::to_value_ptr(pDel) ); + + if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { + --m_ItemCounter; + m_Stat.onRemoveNode( nHeight ); + m_Stat.onExtractMinSuccess(); + return true; + } + + m_Stat.onExtractMinRetry(); + } + } + + bool extract_max_( typename gc::Guard& gDel ) + { + position pos; + + for (;;) { + if ( !find_max_position( pos ) ) { + // The list is empty + m_Stat.onExtractMaxFailed(); + return false; + } + + node_type * pDel = pos.pCur; + + unsigned int nHeight = pDel->height(); + gDel.assign( node_traits::to_value_ptr(pDel) ); + + if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { + --m_ItemCounter; + m_Stat.onRemoveNode( nHeight ); + m_Stat.onExtractMaxSuccess(); + return true; + } + + m_Stat.onExtractMaxRetry(); + } + } + + void increase_height( unsigned int nHeight ) + { + unsigned int nCur = m_nHeight.load( memory_model::memory_order_relaxed ); + if ( nCur < nHeight ) + m_nHeight.compare_exchange_strong( nCur, nHeight, memory_model::memory_order_release, atomics::memory_order_relaxed ); + } + //@endcond + + public: + /// Default constructor + /** + The constructor checks whether the count of guards is enough + for skip-list and may raise an exception if not. + */ + SkipListSet() + : m_Head( c_nMaxHeight ) + , m_nHeight( c_nMinHeight ) + { + static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" ); + + gc::check_available_guards( c_nHazardPtrCount ); + + // Barrier for head node + atomics::atomic_thread_fence( memory_model::memory_order_release ); + } + + /// Clears and destructs the skip-list + ~SkipListSet() + { + clear(); + } + + public: + /// Iterator type + typedef skip_list::details::iterator< gc, node_traits, back_off, false > iterator; + + /// Const iterator type + typedef skip_list::details::iterator< gc, node_traits, back_off, true > const_iterator; + + /// Returns a forward iterator addressing the first element in a set + iterator begin() + { + return iterator( *m_Head.head() ); + } + + /// Returns a forward const iterator addressing the first element in a set + //@{ + const_iterator begin() const + { + return const_iterator( *m_Head.head() ); + } + const_iterator cbegin() + { + return const_iterator( *m_Head.head() ); + } + //@} + + /// Returns a forward iterator that addresses the location succeeding the last element in a set. + iterator end() + { + return iterator(); + } + + /// Returns a forward const iterator that addresses the location succeeding the last element in a set. + //@{ + const_iterator end() const + { + return const_iterator(); + } + const_iterator cend() + { + return const_iterator(); + } + //@} + + public: + /// Inserts new node + /** + The function inserts \p val in the set if it does not contain + an item with key equal to \p val. + + Returns \p true if \p val is placed into the set, \p false otherwise. + */ + bool insert( value_type& val ) + { + return insert( val, []( value_type& ) {} ); + } + + /// Inserts new node + /** + This function is intended for derived non-intrusive containers. + + The function allows to split creating of new item into two part: + - create item with key only + - insert new item into the set + - if inserting is success, calls \p f functor to initialize value-field of \p val. + + The functor signature is: + \code + void func( value_type& val ); + \endcode + where \p val is the item inserted. User-defined functor \p f should guarantee that during changing + \p val no any other changes could be made on this set's item by concurrent threads. + The user-defined functor is called only if the inserting is success and may be passed by reference + using boost::ref + */ + template + bool insert( value_type& val, Func f ) + { + typename gc::Guard gNew; + gNew.assign( &val ); + + node_type * pNode = node_traits::to_node_ptr( val ); + scoped_node_ptr scp( pNode ); + unsigned int nHeight = pNode->height(); + bool bTowerOk = nHeight > 1 && pNode->get_tower() != nullptr; + bool bTowerMade = false; + + position pos; + while ( true ) + { + bool bFound = find_position( val, pos, key_comparator(), true ); + if ( bFound ) { + // scoped_node_ptr deletes the node tower if we create it + if ( !bTowerMade ) + scp.release(); + + m_Stat.onInsertFailed(); + return false; + } + + if ( !bTowerOk ) { + build_node( pNode ); + nHeight = pNode->height(); + bTowerMade = + bTowerOk = true; + } + + if ( !insert_at_position( val, pNode, pos, f )) { + m_Stat.onInsertRetry(); + continue; + } + + increase_height( nHeight ); + ++m_ItemCounter; + m_Stat.onAddNode( nHeight ); + m_Stat.onInsertSuccess(); + scp.release(); + return true; + } + } + + /// Ensures that the \p val exists in the set + /** + The operation performs inserting or changing data with lock-free manner. + + If the item \p val is not found in the set, then \p val is inserted into the set. + Otherwise, the functor \p func is called with item found. + The functor signature is: + \code + void func( bool bNew, value_type& item, value_type& 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 val passed into the \p ensure function + If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments + refer to the same thing. + + The functor can change non-key fields of the \p item; however, \p func must guarantee + that during changing no any other modifications could be made on this item by concurrent threads. + + You can pass \p func argument by value or by reference using boost::ref or cds::ref. + + Returns std::pair where \p first is \p true if operation is successfull, + \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. + */ + template + std::pair ensure( value_type& val, Func func ) + { + typename gc::Guard gNew; + gNew.assign( &val ); + + node_type * pNode = node_traits::to_node_ptr( val ); + scoped_node_ptr scp( pNode ); + unsigned int nHeight = pNode->height(); + bool bTowerOk = nHeight > 1 && pNode->get_tower() != nullptr; + bool bTowerMade = false; + + position pos; + while ( true ) + { + bool bFound = find_position( val, pos, key_comparator(), true ); + if ( bFound ) { + // scoped_node_ptr deletes the node tower if we create it before + if ( !bTowerMade ) + scp.release(); + + cds::unref(func)( false, *node_traits::to_value_ptr(pos.pCur), val ); + m_Stat.onEnsureExist(); + return std::make_pair( true, false ); + } + + if ( !bTowerOk ) { + build_node( pNode ); + nHeight = pNode->height(); + bTowerMade = + bTowerOk = true; + } + + if ( !insert_at_position( val, pNode, pos, [&func]( value_type& item ) { cds::unref(func)( true, item, item ); })) { + m_Stat.onInsertRetry(); + continue; + } + + increase_height( nHeight ); + ++m_ItemCounter; + scp.release(); + m_Stat.onAddNode( nHeight ); + m_Stat.onEnsureNew(); + return std::make_pair( true, true ); + } + } + + /// Unlinks the item \p val from the set + /** + The function searches the item \p val in the set and unlink it from the set + if it is found and is equal to \p val. + + Difference between \ref erase and \p unlink functions: \p erase finds a key + and deletes the item found. \p unlink finds an item by key and deletes it + only if \p val is an item of that set, i.e. the pointer to item found + is equal to &val . + + The \ref disposer specified in \p Traits class template parameter is called + by garbage collector \p GC asynchronously. + + The function returns \p true if success and \p false otherwise. + */ + bool unlink( value_type& val ) + { + position pos; + + if ( !find_position( val, pos, key_comparator(), false ) ) { + m_Stat.onUnlinkFailed(); + return false; + } + + node_type * pDel = pos.pCur; + assert( key_comparator()( *node_traits::to_value_ptr( pDel ), val ) == 0 ); + + unsigned int nHeight = pDel->height(); + typename gc::Guard gDel; + gDel.assign( node_traits::to_value_ptr(pDel) ); + + if ( node_traits::to_value_ptr( pDel ) == &val && try_remove_at( pDel, pos, [](value_type const&) {} )) { + --m_ItemCounter; + m_Stat.onRemoveNode( nHeight ); + m_Stat.onUnlinkSuccess(); + return true; + } + + m_Stat.onUnlinkFailed(); + return false; + } + + /// Extracts the item from the set with specified \p key + /** \anchor cds_intrusive_SkipListSet_hp_extract + The function searches an item with key equal to \p key in the set, + unlinks it from the set, and returns it in \p dest parameter. + If the item with key equal to \p key is not found the function returns \p false. + + Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. + + The \ref disposer specified in \p Traits class template parameter is called automatically + by garbage collector \p GC specified in class' template parameters when returned \ref guarded_ptr object + will be destroyed or released. + @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. + + Usage: + \code + typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; + skip_list theList; + // ... + { + skip_list::guarded_ptr gp; + theList.extract( gp, 5 ); + // Deal with gp + // ... + + // Destructor of gp releases internal HP guard + } + \endcode + */ + template + bool extract( guarded_ptr& dest, Q const& key ) + { + return extract_( dest.guard(), key, key_comparator() ); + } + + /// Extracts the item from the set with comparing functor \p pred + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_extract "extract(Q const&)" + but \p pred predicate is used for key comparing. + + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool extract_with( guarded_ptr& dest, Q const& key, Less pred ) + { + return extract_( dest.guard(), key, cds::opt::details::make_comparator_from_less() ); + } + + /// Extracts an item with minimal key from the list + /** + The function searches an item with minimal key, unlinks it, and returns the item found in \p dest parameter. + If the skip-list is empty the function returns \p false. + + @note Due the concurrent nature of the list, the function extracts nearly minimum key. + It means that the function gets leftmost item and tries to unlink it. + During unlinking, a concurrent thread may insert an item with key less than leftmost item's key. + So, the function returns the item with minimum key at the moment of list traversing. + + The \ref disposer specified in \p Traits class template parameter is called + by garbage collector \p GC automatically when returned \ref guarded_ptr object + will be destroyed or released. + @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. + + Usage: + \code + typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; + skip_list theList; + // ... + { + skip_list::guarded_ptr gp; + if ( theList.extract_min( gp )) { + // Deal with gp + //... + } + // Destructor of gp releases internal HP guard + } + \endcode + */ + bool extract_min( guarded_ptr& dest) + { + return extract_min_( dest.guard() ); + } + + /// Extracts an item with maximal key from the list + /** + The function searches an item with maximal key, unlinks it, and returns the pointer to item found in \p dest parameter. + If the skip-list is empty the function returns empty \p guarded_ptr. + + @note Due the concurrent nature of the list, the function extracts nearly maximal key. + It means that the function gets rightmost item and tries to unlink it. + During unlinking, a concurrent thread may insert an item with key greater than rightmost item's key. + So, the function returns the item with maximum key at the moment of list traversing. + + The \ref disposer specified in \p Traits class template parameter is called + by garbage collector \p GC asynchronously when returned \ref guarded_ptr object + will be destroyed or released. + @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. + + Usage: + \code + typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; + skip_list theList; + // ... + { + skip_list::guarded_ptr gp; + if ( theList.extract_max( gp )) { + // Deal with gp + //... + } + // Destructor of gp releases internal HP guard + } + \endcode + */ + bool extract_max( guarded_ptr& dest ) + { + return extract_max_( dest.guard() ); + } + + /// Deletes the item from the set + /** \anchor cds_intrusive_SkipListSet_hp_erase + The function searches an item with key equal to \p val in the set, + unlinks it from the set, and returns \p true. + If the item with key equal to \p val is not found the function return \p false. + + Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. + */ + template + bool erase( Q const& val ) + { + return erase_( val, key_comparator(), [](value_type const&) {} ); + } + + /// Deletes the item from the set with comparing functor \p pred + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_erase "erase(Q const&)" + but \p pred predicate is used for key comparing. + + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool erase_with( Q const& val, Less pred ) + { + return erase_( val, cds::opt::details::make_comparator_from_less(), [](value_type const&) {} ); + } + + /// Deletes the item from the set + /** \anchor cds_intrusive_SkipListSet_hp_erase_func + The function searches an item with key equal to \p val in the set, + call \p f functor with item found, unlinks it from the set, and returns \p true. + The \ref disposer specified in \p Traits class template parameter is called + by garbage collector \p GC asynchronously. + + The \p Func interface is + \code + struct functor { + void operator()( value_type const& item ); + }; + \endcode + The functor can be passed by reference with boost:ref + + If the item with key equal to \p val is not found the function return \p false. + + Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. + */ + template + bool erase( Q const& val, Func f ) + { + return erase_( val, key_comparator(), f ); + } + + /// Deletes the item from the set with comparing functor \p pred + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_erase_func "erase(Q const&, Func)" + but \p pred predicate is used for key comparing. + + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool erase_with( Q const& val, Less pred, Func f ) + { + return erase_( val, cds::opt::details::make_comparator_from_less(), f ); + } + + /// Finds the key \p val + /** \anchor cds_intrusive_SkipListSet_hp_find_func + The function searches the item with key equal to \p val and calls the functor \p f for item found. + The interface of \p Func functor is: + \code + struct functor { + void operator()( value_type& item, Q& val ); + }; + \endcode + where \p item is the item found, \p val is the find function argument. + + You can pass \p f argument by value or by reference using boost::ref or cds::ref. + + The functor can change non-key fields of \p item. Note that the functor is only guarantee + that \p item cannot be disposed during functor is executing. + The functor does not serialize simultaneous access to the set \p item. If such access is + possible you must provide your own synchronization schema on item level to exclude unsafe item modifications. + + The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor + can modify both arguments. + + Note the compare functor specified for class \p Traits template parameter + should accept a parameter of type \p Q that can be not the same as \p value_type. + + The function returns \p true if \p val is found, \p false otherwise. + */ + template + bool find( Q& val, Func f ) + { + return find_with_( val, key_comparator(), f ); + } + + /// Finds the key \p val with \p pred predicate for comparing + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_func "find(Q&, Func)" + but \p pred is used for key compare. + + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool find_with( Q& val, Less pred, Func f ) + { + return find_with_( val, cds::opt::details::make_comparator_from_less(), f ); + } + + /// Finds the key \p val + /** \anchor cds_intrusive_SkipListSet_hp_find_cfunc + The function searches the item with key equal to \p val and calls the functor \p f for item found. + The interface of \p Func functor is: + \code + struct functor { + void operator()( value_type& item, Q const& val ); + }; + \endcode + where \p item is the item found, \p val is the find function argument. + + You can pass \p f argument by value or by reference using boost::ref or cds::ref. + + The functor can change non-key fields of \p item. Note that the functor is only guarantee + that \p item cannot be disposed during functor is executing. + The functor does not serialize simultaneous access to the set \p item. If such access is + possible you must provide your own synchronization schema on item level to exclude unsafe item modifications. + + Note the compare functor specified for class \p Traits template parameter + should accept a parameter of type \p Q that can be not the same as \p value_type. + + The function returns \p true if \p val is found, \p false otherwise. + */ + template + bool find( Q const& val, Func f ) + { + return find_with_( val, key_comparator(), f ); + } + + /// Finds the key \p val with \p pred predicate for comparing + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_cfunc "find(Q const&, Func)" + but \p pred is used for key compare. + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool find_with( Q const& val, Less pred, Func f ) + { + return find_with_( val, cds::opt::details::make_comparator_from_less(), f ); + } + + /// Finds the key \p val + /** \anchor cds_intrusive_SkipListSet_hp_find_val + The function searches the item with key equal to \p val + and returns \p true if it is found, and \p false otherwise. + + Note the compare functor specified for class \p Traits template parameter + should accept a parameter of type \p Q that can be not the same as \p value_type. + */ + template + bool find( Q const & val ) + { + return find_with_( val, key_comparator(), [](value_type& , Q const& ) {} ); + } + + /// Finds the key \p val with comparing functor \p pred + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_val "find(Q const&)" + but \p pred is used for comparing the keys. + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool find_with( Q const& val, Less pred ) + { + return find_with_( val, cds::opt::details::make_comparator_from_less(), [](value_type& , Q const& ) {} ); + } + + /// Finds the key \p val and return the item found + /** \anchor cds_intrusive_SkipListSet_hp_get + The function searches the item with key equal to \p val + and assigns the item found to guarded pointer \p ptr. + The function returns \p true if \p val is found, and \p false otherwise. + If \p val is not found the \p ptr parameter is not changed. + + The \ref disposer specified in \p Traits class template parameter is called + by garbage collector \p GC asynchronously when returned \ref guarded_ptr object + will be destroyed or released. + @note Each \p guarded_ptr object uses one GC's guard which can be limited resource. + + Usage: + \code + typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; + skip_list theList; + // ... + { + skip_list::guarded_ptr gp; + if ( theList.get( gp, 5 )) { + // Deal with gp + //... + } + // Destructor of guarded_ptr releases internal HP guard + } + \endcode + + Note the compare functor specified for class \p Traits template parameter + should accept a parameter of type \p Q that can be not the same as \p value_type. + */ + template + bool get( guarded_ptr& ptr, Q const& val ) + { + return get_with_( ptr.guard(), val, key_comparator() ); + } + + /// Finds the key \p val and return the item found + /** + The function is an analog of \ref cds_intrusive_SkipListSet_hp_get "get( guarded_ptr& ptr, Q const&)" + but \p pred is used for comparing the keys. + + \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q + in any order. + \p pred must imply the same element order as the comparator used for building the set. + */ + template + bool get_with( guarded_ptr& ptr, Q const& val, Less pred ) + { + return get_with_( ptr.guard(), val, cds::opt::details::make_comparator_from_less() ); + } + + /// Returns item count in the set + /** + The value returned depends on item counter type provided by \p Traits template parameter. + If it is atomicity::empty_item_counter this function always returns 0. + Therefore, the function is not suitable for checking the set emptiness, use \ref empty + member function for this purpose. + */ + size_t size() const + { + return m_ItemCounter; + } + + /// Checks if the set is empty + bool empty() const + { + return m_Head.head()->next( 0 ).load( memory_model::memory_order_relaxed ) == nullptr; + } + + /// Clears the set (non-atomic) + /** + The function unlink all items from the set. + The function is not atomic, i.e., in multi-threaded environment with parallel insertions + this sequence + \code + set.clear(); + assert( set.empty() ); + \endcode + the assertion could be raised. + + For each item the \ref disposer will be called after unlinking. + */ + void clear() + { + guarded_ptr gp; + while ( extract_min( gp )); + } + + /// Returns maximum height of skip-list. The max height is a constant for each object and does not exceed 32. + static CDS_CONSTEXPR unsigned int max_height() CDS_NOEXCEPT + { + return c_nMaxHeight; + } + + /// Returns const reference to internal statistics + stat const& statistics() const + { + return m_Stat; + } + + }; + +}} // namespace cds::intrusive + + +#endif // #ifndef __CDS_INTRUSIVE_IMPL_SKIP_LIST_H diff --git a/cds/intrusive/skip_list_hp.h b/cds/intrusive/skip_list_hp.h index 2df5fd33..47841032 100644 --- a/cds/intrusive/skip_list_hp.h +++ b/cds/intrusive/skip_list_hp.h @@ -4,6 +4,6 @@ #define __CDS_INTRUSIVE_SKIP_LIST_HP_H #include -#include +#include #endif diff --git a/cds/intrusive/skip_list_hrc.h b/cds/intrusive/skip_list_hrc.h index 67bcff64..dddfbca6 100644 --- a/cds/intrusive/skip_list_hrc.h +++ b/cds/intrusive/skip_list_hrc.h @@ -3,7 +3,7 @@ #ifndef __CDS_INTRUSIVE_SKIP_LIST_HRC_H #define __CDS_INTRUSIVE_SKIP_LIST_HRC_H -#include +#include #include //@cond diff --git a/cds/intrusive/skip_list_impl.h b/cds/intrusive/skip_list_impl.h deleted file mode 100644 index 034222a1..00000000 --- a/cds/intrusive/skip_list_impl.h +++ /dev/null @@ -1,1630 +0,0 @@ -//$$CDS-header$$ - -#ifndef __CDS_INTRUSIVE_SKIP_LIST_IMPL_H -#define __CDS_INTRUSIVE_SKIP_LIST_IMPL_H - -#include -#include -#include -#include -#include -#include -#include - -namespace cds { namespace intrusive { - - //@cond - namespace skip_list { namespace details { - - template - class iterator { - public: - typedef GC gc; - typedef NodeTraits node_traits; - typedef BackOff back_off; - typedef typename node_traits::node_type node_type; - typedef typename node_traits::value_type value_type; - static bool const c_isConst = IsConst; - - typedef typename std::conditional< c_isConst, value_type const &, value_type &>::type value_ref; - - protected: - typedef typename node_type::marked_ptr marked_ptr; - typedef typename node_type::atomic_marked_ptr atomic_marked_ptr; - - typename gc::Guard m_guard; - node_type * m_pNode; - - protected: - static value_type * gc_protect( marked_ptr p ) - { - return node_traits::to_value_ptr( p.ptr() ); - } - - void next() - { - typename gc::Guard g; - g.copy( m_guard ); - back_off bkoff; - - for (;;) { - if ( m_pNode->next( m_pNode->height() - 1 ).load( atomics::memory_order_acquire ).bits() ) { - // Current node is marked as deleted. So, its next pointer can point to anything - // In this case we interrupt our iteration and returns end() iterator. - *this = iterator(); - return; - } - - marked_ptr p = m_guard.protect( (*m_pNode)[0], gc_protect ); - node_type * pp = p.ptr(); - if ( p.bits() ) { - // p is marked as deleted. Spin waiting for physical removal - bkoff(); - continue; - } - else if ( pp && pp->next( pp->height() - 1 ).load( atomics::memory_order_relaxed ).bits() ) { - // p is marked as deleted. Spin waiting for physical removal - bkoff(); - continue; - } - - m_pNode = pp; - break; - } - } - - public: // for internal use only!!! - iterator( node_type& refHead ) - : m_pNode( nullptr ) - { - back_off bkoff; - - for (;;) { - marked_ptr p = m_guard.protect( refHead[0], gc_protect ); - if ( !p.ptr() ) { - // empty skip-list - m_guard.clear(); - break; - } - - node_type * pp = p.ptr(); - // Logically deleted node is marked from highest level - if ( !pp->next( pp->height() - 1 ).load( atomics::memory_order_acquire ).bits() ) { - m_pNode = pp; - break; - } - - bkoff(); - } - } - - public: - iterator() - : m_pNode( nullptr ) - {} - - iterator( iterator const& s) - : m_pNode( s.m_pNode ) - { - m_guard.assign( node_traits::to_value_ptr(m_pNode) ); - } - - value_type * operator ->() const - { - assert( m_pNode != nullptr ); - assert( node_traits::to_value_ptr( m_pNode ) != nullptr ); - - return node_traits::to_value_ptr( m_pNode ); - } - - value_ref operator *() const - { - assert( m_pNode != nullptr ); - assert( node_traits::to_value_ptr( m_pNode ) != nullptr ); - - return *node_traits::to_value_ptr( m_pNode ); - } - - /// Pre-increment - iterator& operator ++() - { - next(); - return *this; - } - - iterator& operator = (const iterator& src) - { - m_pNode = src.m_pNode; - m_guard.copy( src.m_guard ); - return *this; - } - - template - bool operator ==(iterator const& i ) const - { - return m_pNode == i.m_pNode; - } - template - bool operator !=(iterator const& i ) const - { - return !( *this == i ); - } - }; - }} // namespace skip_list::details - //@endcond - - /// Lock-free skip-list set - /** @ingroup cds_intrusive_map - @anchor cds_intrusive_SkipListSet_hp - - The implementation of well-known probabilistic data structure called skip-list - invented by W.Pugh in his papers: - - [1989] W.Pugh Skip Lists: A Probabilistic Alternative to Balanced Trees - - [1990] W.Pugh A Skip List Cookbook - - A skip-list is a probabilistic data structure that provides expected logarithmic - time search without the need of rebalance. The skip-list is a collection of sorted - linked list. Nodes are ordered by key. Each node is linked into a subset of the lists. - Each list has a level, ranging from 0 to 32. The bottom-level list contains - all the nodes, and each higher-level list is a sublist of the lower-level lists. - Each node is created with a random top level (with a random height), and belongs - to all lists up to that level. The probability that a node has the height 1 is 1/2. - The probability that a node has the height N is 1/2 ** N (more precisely, - the distribution depends on an random generator provided, but our generators - have this property). - - The lock-free variant of skip-list is implemented according to book - - [2008] M.Herlihy, N.Shavit "The Art of Multiprocessor Programming", - chapter 14.4 "A Lock-Free Concurrent Skiplist". - \note The algorithm described in this book cannot be directly adapted for C++ (roughly speaking, - the algo contains a lot of bugs). The \b libcds implementation applies the approach discovered - by M.Michael in his \ref cds_intrusive_MichaelList_hp "lock-free linked list". - - Template arguments: - - \p GC - Garbage collector used. Note the \p GC must be the same as the GC used for item type \p T (see skip_list::node). - - \p T - type to be stored in the list. The type must be based on skip_list::node (for skip_list::base_hook) - or it must have a member of type skip_list::node (for skip_list::member_hook). - - \p Traits - type traits. See skip_list::type_traits for explanation. - - It is possible to declare option-based list with cds::intrusive::skip_list::make_traits metafunction istead of \p Traits template - argument. - Template argument list \p Options of cds::intrusive::skip_list::make_traits metafunction are: - - opt::hook - hook used. Possible values are: skip_list::base_hook, skip_list::member_hook, skip_list::traits_hook. - If the option is not specified, skip_list::base_hook<> and gc::HP is used. - - opt::compare - key comparison functor. No default functor is provided. - If the option is not specified, the opt::less is used. - - opt::less - specifies binary predicate used for key comparison. Default is \p std::less. - - opt::disposer - the functor used for dispose removed items. Default is opt::v::empty_disposer. Due the nature - of GC schema the disposer may be called asynchronously. - - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting. - - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default) - or opt::v::sequential_consistent (sequentially consisnent memory model). - - skip_list::random_level_generator - random level generator. Can be skip_list::xorshift, skip_list::turbo_pascal or - user-provided one. See skip_list::random_level_generator option description for explanation. - Default is \p %skip_list::turbo_pascal. - - opt::allocator - although the skip-list is an intrusive container, - an allocator should be provided to maintain variable randomly-calculated height of the node - since the node can contain up to 32 next pointers. The allocator option is used to allocate an array of next pointers - for nodes which height is more than 1. Default is \ref CDS_DEFAULT_ALLOCATOR. - - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::Default is used. - - opt::stat - internal statistics. Available types: skip_list::stat, skip_list::empty_stat (the default) - - \warning The skip-list requires up to 67 hazard pointers that may be critical for some GCs for which - the guard count is limited (like as gc::HP, gc::HRC). Those GCs should be explicitly initialized with - hazard pointer enough: \code cds::gc::HP myhp( 67 ) \endcode. Otherwise an run-time exception may be raised - when you try to create skip-list object. - - \note There are several specializations of \p %SkipListSet for each \p GC. You should include: - - for gc::HP garbage collector - - for gc::HRC garbage collector - - for gc::PTB garbage collector - - for \ref cds_intrusive_SkipListSet_nogc for persistent set - - for \ref cds_intrusive_SkipListSet_rcu "RCU type" - - Iterators - - The class supports a forward iterator (\ref iterator and \ref const_iterator). - The iteration is ordered. - The iterator object is thread-safe: the element pointed by the iterator object is guarded, - so, the element cannot be reclaimed while the iterator object is alive. - However, passing an iterator object between threads is dangerous. - - \warning Due to concurrent nature of skip-list set it is not guarantee that you can iterate - all elements in the set: any concurrent deletion can exclude the element - pointed by the iterator from the set, and your iteration can be terminated - before end of the set. Therefore, such iteration is more suitable for debugging purpose only - - Remember, each iterator object requires 2 additional hazard pointers, that may be - a limited resource for \p GC like as gc::HP and gc::HRC (for gc::PTB the count of - guards is unlimited). - - The iterator class supports the following minimalistic interface: - \code - struct iterator { - // Default ctor - iterator(); - - // Copy ctor - iterator( iterator const& s); - - value_type * operator ->() const; - value_type& operator *() const; - - // Pre-increment - iterator& operator ++(); - - // Copy assignment - iterator& operator = (const iterator& src); - - bool operator ==(iterator const& i ) const; - bool operator !=(iterator const& i ) const; - }; - \endcode - Note, the iterator object returned by \ref end, \p cend member functions points to \p nullptr and should not be dereferenced. - - How to use - - You should incorporate skip_list::node into your struct \p T and provide - appropriate skip_list::type_traits::hook in your \p Traits template parameters. Usually, for \p Traits you - define a struct based on skip_list::type_traits. - - Example for gc::HP and base hook: - \code - // Include GC-related skip-list specialization - #include - - // Data stored in skip list - struct my_data: public cds::intrusive::skip_list::node< cds::gc::HP > - { - // key field - std::string strKey; - - // other data - // ... - }; - - // my_data compare functor - struct my_data_cmp { - int operator()( const my_data& d1, const my_data& d2 ) - { - return d1.strKey.compare( d2.strKey ); - } - - int operator()( const my_data& d, const std::string& s ) - { - return d.strKey.compare(s); - } - - int operator()( const std::string& s, const my_data& d ) - { - return s.compare( d.strKey ); - } - }; - - - // Declare type_traits - struct my_traits: public cds::intrusive::skip_list::type_traits - { - typedef cds::intrusive::skip_list::base_hook< cds::opt::gc< cds::gc::HP > > hook; - typedef my_data_cmp compare; - }; - - // Declare skip-list set type - typedef cds::intrusive::SkipListSet< cds::gc::HP, my_data, my_traits > traits_based_set; - \endcode - - Equivalent option-based code: - \code - // GC-related specialization - #include - - struct my_data { - // see above - }; - struct compare { - // see above - }; - - // Declare option-based skip-list set - typedef cds::intrusive::SkipListSet< cds::gc::HP - ,my_data - , typename cds::intrusive::skip_list::make_traits< - cds::intrusive::opt::hook< cds::intrusive::skip_list::base_hook< cds::opt::gc< cds::gc::HP > > > - ,cds::intrusive::opt::compare< my_data_cmp > - >::type - > option_based_set; - - \endcode - */ - template < - class GC - ,typename T -#ifdef CDS_DOXYGEN_INVOKED - ,typename Traits = skip_list::type_traits -#else - ,typename Traits -#endif - > - class SkipListSet - { - public: - typedef T value_type ; ///< type of value stored in the skip-list - typedef Traits options ; ///< Traits template parameter - - typedef typename options::hook hook ; ///< hook type - typedef typename hook::node_type node_type ; ///< node type - -# ifdef CDS_DOXYGEN_INVOKED - typedef implementation_defined key_comparator ; ///< key comparison functor based on opt::compare and opt::less option setter. -# else - typedef typename opt::details::make_comparator< value_type, options >::type key_comparator; -# endif - - typedef typename options::disposer disposer ; ///< disposer used - typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits - - typedef GC gc ; ///< Garbage collector - typedef typename options::item_counter item_counter ; ///< Item counting policy used - typedef typename options::memory_model memory_model ; ///< Memory ordering. See cds::opt::memory_model option - typedef typename options::random_level_generator random_level_generator ; ///< random level generator - typedef typename options::allocator allocator_type ; ///< allocator for maintaining array of next pointers of the node - typedef typename options::back_off back_off ; ///< Back-off strategy - typedef typename options::stat stat ; ///< internal statistics type - - public: - typedef cds::gc::guarded_ptr< gc, value_type > guarded_ptr; ///< Guarded pointer - - /// Max node height. The actual node height should be in range [0 .. c_nMaxHeight) - /** - The max height is specified by \ref skip_list::random_level_generator "random level generator" constant \p m_nUpperBound - but it should be no more than 32 (\ref skip_list::c_nHeightLimit). - */ - static unsigned int const c_nMaxHeight = std::conditional< - (random_level_generator::c_nUpperBound <= skip_list::c_nHeightLimit), - std::integral_constant< unsigned int, random_level_generator::c_nUpperBound >, - std::integral_constant< unsigned int, skip_list::c_nHeightLimit > - >::type::value; - - //@cond - static unsigned int const c_nMinHeight = 5; - //@endcond - - protected: - typedef typename node_type::atomic_marked_ptr atomic_node_ptr ; ///< Atomic marked node pointer - typedef typename node_type::marked_ptr marked_node_ptr ; ///< Node marked pointer - - protected: - //@cond - typedef skip_list::details::intrusive_node_builder< node_type, atomic_node_ptr, allocator_type > intrusive_node_builder; - - typedef typename std::conditional< - std::is_same< typename options::internal_node_builder, cds::opt::none >::value - ,intrusive_node_builder - ,typename options::internal_node_builder - >::type node_builder; - - typedef std::unique_ptr< node_type, typename node_builder::node_disposer > scoped_node_ptr; - - // c_nMaxHeight * 2 - pPred/pSucc guards - // + 1 - for erase, unlink - // + 1 - for clear - static size_t const c_nHazardPtrCount = c_nMaxHeight * 2 + 2; - struct position { - node_type * pPrev[ c_nMaxHeight ]; - node_type * pSucc[ c_nMaxHeight ]; - - typename gc::template GuardArray< c_nMaxHeight * 2 > guards ; ///< Guards array for pPrev/pSucc - - node_type * pCur ; // guarded by guards; needed only for *ensure* function - }; - //@endcond - - protected: - skip_list::details::head_node< node_type > m_Head ; ///< head tower (max height) - - item_counter m_ItemCounter ; ///< item counter - random_level_generator m_RandomLevelGen ; ///< random level generator instance - atomics::atomic m_nHeight ; ///< estimated high level - mutable stat m_Stat ; ///< internal statistics - - protected: - //@cond - unsigned int random_level() - { - // Random generator produces a number from range [0..31] - // We need a number from range [1..32] - return m_RandomLevelGen() + 1; - } - - template - node_type * build_node( Q v ) - { - return node_builder::make_tower( v, m_RandomLevelGen ); - } - - static value_type * gc_protect( marked_node_ptr p ) - { - return node_traits::to_value_ptr( p.ptr() ); - } - - static void dispose_node( value_type * pVal ) - { - assert( pVal != nullptr ); - typename node_builder::node_disposer()( node_traits::to_node_ptr(pVal) ); - disposer()( pVal ); - } - - template - bool find_position( Q const& val, position& pos, Compare cmp, bool bStopIfFound ) - { - node_type * pPred; - marked_node_ptr pSucc; - marked_node_ptr pCur; - - // Hazard pointer array: - // pPred: [nLevel * 2] - // pSucc: [nLevel * 2 + 1] - - retry: - pPred = m_Head.head(); - int nCmp = 1; - - for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { - pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); - while ( true ) { - pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); - if ( pCur.bits() ) { - // pCur.bits() means that pPred is logically deleted - goto retry; - } - - if ( pCur.ptr() == nullptr ) { - // end of the list at level nLevel - goto next level - break; - } - - // pSucc contains deletion mark for pCur - pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); - - if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) - goto retry; - - if ( pSucc.bits() ) { - // pCur is marked, i.e. logically deleted. - marked_node_ptr p( pCur.ptr() ); - if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), - memory_model::memory_order_release, atomics::memory_order_relaxed )) - { - if ( nLevel == 0 ) { - gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); - m_Stat.onEraseWhileFind(); - } - } - goto retry; - } - else { - nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr()), val ); - if ( nCmp < 0 ) { - pPred = pCur.ptr(); - pos.guards.copy( nLevel * 2, nLevel * 2 + 1 ) ; // pPrev guard := cur guard - } - else if ( nCmp == 0 && bStopIfFound ) - goto found; - else - break; - } - } - - // Next level - pos.pPrev[ nLevel ] = pPred; - pos.pSucc[ nLevel ] = pCur.ptr(); - } - - if ( nCmp != 0 ) - return false; - - found: - pos.pCur = pCur.ptr(); - return pCur.ptr() && nCmp == 0; - } - - bool find_min_position( position& pos ) - { - node_type * pPred; - marked_node_ptr pSucc; - marked_node_ptr pCur; - - // Hazard pointer array: - // pPred: [nLevel * 2] - // pSucc: [nLevel * 2 + 1] - - retry: - pPred = m_Head.head(); - - for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { - pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); - pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); - - // pCur.bits() means that pPred is logically deleted - // head cannot be deleted - assert( pCur.bits() == 0 ); - - if ( pCur.ptr() ) { - - // pSucc contains deletion mark for pCur - pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); - - if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) - goto retry; - - if ( pSucc.bits() ) { - // pCur is marked, i.e. logically deleted. - marked_node_ptr p( pCur.ptr() ); - if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), - memory_model::memory_order_release, atomics::memory_order_relaxed )) - { - if ( nLevel == 0 ) - gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); - } - goto retry; - } - } - - // Next level - pos.pPrev[ nLevel ] = pPred; - pos.pSucc[ nLevel ] = pCur.ptr(); - } - - return (pos.pCur = pCur.ptr()) != nullptr; - } - - bool find_max_position( position& pos ) - { - node_type * pPred; - marked_node_ptr pSucc; - marked_node_ptr pCur; - - // Hazard pointer array: - // pPred: [nLevel * 2] - // pSucc: [nLevel * 2 + 1] - - retry: - pPred = m_Head.head(); - - for ( int nLevel = static_cast( c_nMaxHeight - 1 ); nLevel >= 0; --nLevel ) { - pos.guards.assign( nLevel * 2, node_traits::to_value_ptr( pPred )); - while ( true ) { - pCur = pos.guards.protect( nLevel * 2 + 1, pPred->next( nLevel ), gc_protect ); - if ( pCur.bits() ) { - // pCur.bits() means that pPred is logically deleted - goto retry; - } - - if ( pCur.ptr() == nullptr ) { - // end of the list at level nLevel - goto next level - break; - } - - // pSucc contains deletion mark for pCur - pSucc = pCur->next( nLevel ).load( memory_model::memory_order_relaxed ); - - if ( pPred->next( nLevel ).load( memory_model::memory_order_relaxed ).all() != pCur.ptr() ) - goto retry; - - if ( pSucc.bits() ) { - // pCur is marked, i.e. logically deleted. - marked_node_ptr p( pCur.ptr() ); - if ( pPred->next( nLevel ).compare_exchange_strong( p, marked_node_ptr( pSucc.ptr() ), - memory_model::memory_order_release, atomics::memory_order_relaxed )) - { - if ( nLevel == 0 ) - gc::retire( node_traits::to_value_ptr( pCur.ptr() ), dispose_node ); - } - goto retry; - } - else { - if ( !pSucc.ptr() ) - break; - - pPred = pCur.ptr(); - pos.guards.copy( nLevel * 2, nLevel * 2 + 1 ); // pPrev guard := cur guard - //pos.guards.copy( nLevel * 2, gCur ) ; // pPrev guard := gCur - } - } - - // Next level - pos.pPrev[ nLevel ] = pPred; - pos.pSucc[ nLevel ] = pCur.ptr(); - } - - return (pos.pCur = pCur.ptr()) != nullptr; - } - - template - bool insert_at_position( value_type& val, node_type * pNode, position& pos, Func f ) - { - unsigned int nHeight = pNode->height(); - - for ( unsigned int nLevel = 1; nLevel < nHeight; ++nLevel ) - pNode->next(nLevel).store( marked_node_ptr(), memory_model::memory_order_relaxed ); - - { - marked_node_ptr p( pos.pSucc[0] ); - pNode->next( 0 ).store( p, memory_model::memory_order_release ); - if ( !pos.pPrev[0]->next(0).compare_exchange_strong( p, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed ) ) { - return false; - } - cds::unref( f )( val ); - } - - for ( unsigned int nLevel = 1; nLevel < nHeight; ++nLevel ) { - marked_node_ptr p; - while ( true ) { - marked_node_ptr q( pos.pSucc[ nLevel ]); - if ( !pNode->next( nLevel ).compare_exchange_strong( p, q, memory_model::memory_order_release, atomics::memory_order_relaxed )) { - // pNode has been marked as removed while we are inserting it - // Stop inserting - assert( p.bits() ); - m_Stat.onLogicDeleteWhileInsert(); - return true; - } - p = q; - if ( pos.pPrev[nLevel]->next(nLevel).compare_exchange_strong( q, marked_node_ptr( pNode ), memory_model::memory_order_release, atomics::memory_order_relaxed ) ) - break; - - // Renew insert position - m_Stat.onRenewInsertPosition(); - if ( !find_position( val, pos, key_comparator(), false )) { - // The node has been deleted while we are inserting it - m_Stat.onNotFoundWhileInsert(); - return true; - } - } - } - return true; - } - - template - bool try_remove_at( node_type * pDel, position& pos, Func f ) - { - assert( pDel != nullptr ); - - marked_node_ptr pSucc; - typename gc::Guard gSucc; - - // logical deletion (marking) - for ( unsigned int nLevel = pDel->height() - 1; nLevel > 0; --nLevel ) { - while ( true ) { - pSucc = gSucc.protect( pDel->next(nLevel), gc_protect ); - if ( pSucc.bits() || pDel->next(nLevel).compare_exchange_weak( pSucc, pSucc | 1, - memory_model::memory_order_acquire, atomics::memory_order_relaxed )) - { - break; - } - } - } - - while ( true ) { - pSucc = gSucc.protect( pDel->next(0), gc_protect ); - marked_node_ptr p( pSucc.ptr() ); - if ( pDel->next(0).compare_exchange_strong( p, marked_node_ptr(p.ptr(), 1), - memory_model::memory_order_acquire, atomics::memory_order_relaxed )) - { - cds::unref(f)( *node_traits::to_value_ptr( pDel )); - - // Physical deletion - // try fast erase - p = pDel; - for ( int nLevel = static_cast( pDel->height() - 1 ); nLevel >= 0; --nLevel ) { - pSucc = gSucc.protect( pDel->next(nLevel), gc_protect ); - if ( !pos.pPrev[nLevel]->next(nLevel).compare_exchange_strong( p, marked_node_ptr(pSucc.ptr()), - memory_model::memory_order_release, atomics::memory_order_relaxed) ) - { - // Make slow erase - find_position( *node_traits::to_value_ptr( pDel ), pos, key_comparator(), false ); - m_Stat.onSlowErase(); - return true; - } - } - - // Fast erasing success - gc::retire( node_traits::to_value_ptr( pDel ), dispose_node ); - m_Stat.onFastErase(); - return true; - } - else { - if ( p.bits() ) { - return false; - } - } - } - } - - enum finsd_fastpath_result { - find_fastpath_found, - find_fastpath_not_found, - find_fastpath_abort - }; - template - finsd_fastpath_result find_fastpath( Q& val, Compare cmp, Func f ) - { - node_type * pPred; - typename gc::template GuardArray<2> guards; - marked_node_ptr pCur; - marked_node_ptr pNull; - - back_off bkoff; - - pPred = m_Head.head(); - for ( int nLevel = static_cast( m_nHeight.load(memory_model::memory_order_relaxed) - 1 ); nLevel >= 0; --nLevel ) { - pCur = guards.protect( 1, pPred->next(nLevel), gc_protect ); - if ( pCur == pNull ) - continue; - - while ( pCur != pNull ) { - if ( pCur.bits() ) { - unsigned int nAttempt = 0; - while ( pCur.bits() && nAttempt++ < 16 ) { - bkoff(); - pCur = guards.protect( 1, pPred->next(nLevel), gc_protect ); - } - bkoff.reset(); - - if ( pCur.bits() ) { - // Maybe, we are on deleted node sequence - // Abort searching, try slow-path - return find_fastpath_abort; - } - } - - if ( pCur.ptr() ) { - int nCmp = cmp( *node_traits::to_value_ptr( pCur.ptr() ), val ); - if ( nCmp < 0 ) { - guards.copy( 0, 1 ); - pPred = pCur.ptr(); - pCur = guards.protect( 1, pCur->next(nLevel), gc_protect ); - } - else if ( nCmp == 0 ) { - // found - cds::unref(f)( *node_traits::to_value_ptr( pCur.ptr() ), val ); - return find_fastpath_found; - } - else // pCur > val - go down - break; - } - } - } - - return find_fastpath_not_found; - } - - template - bool find_slowpath( Q& val, Compare cmp, Func f ) - { - position pos; - if ( find_position( val, pos, cmp, true )) { - assert( cmp( *node_traits::to_value_ptr( pos.pCur ), val ) == 0 ); - - cds::unref(f)( *node_traits::to_value_ptr( pos.pCur ), val ); - return true; - } - else - return false; - } - - template - bool find_with_( Q& val, Compare cmp, Func f ) - { - switch ( find_fastpath( val, cmp, f )) { - case find_fastpath_found: - m_Stat.onFindFastSuccess(); - return true; - case find_fastpath_not_found: - m_Stat.onFindFastFailed(); - return false; - default: - break; - } - - if ( find_slowpath( val, cmp, f )) { - m_Stat.onFindSlowSuccess(); - return true; - } - - m_Stat.onFindSlowFailed(); - return false; - } - - template - bool get_with_( typename gc::Guard& guard, Q const& val, Compare cmp ) - { - return find_with_( val, cmp, [&guard](value_type& found, Q const& ) { guard.assign(&found); } ); - } - - template - bool erase_( Q const& val, Compare cmp, Func f ) - { - position pos; - - if ( !find_position( val, pos, cmp, false ) ) { - m_Stat.onEraseFailed(); - return false; - } - - node_type * pDel = pos.pCur; - typename gc::Guard gDel; - gDel.assign( node_traits::to_value_ptr(pDel) ); - assert( cmp( *node_traits::to_value_ptr( pDel ), val ) == 0 ); - - unsigned int nHeight = pDel->height(); - if ( try_remove_at( pDel, pos, f )) { - --m_ItemCounter; - m_Stat.onRemoveNode( nHeight ); - m_Stat.onEraseSuccess(); - return true; - } - - m_Stat.onEraseFailed(); - return false; - } - - template - bool extract_( typename gc::Guard& guard, Q const& val, Compare cmp ) - { - position pos; - - for (;;) { - if ( !find_position( val, pos, cmp, false ) ) { - m_Stat.onExtractFailed(); - return false; - } - - node_type * pDel = pos.pCur; - guard.assign( node_traits::to_value_ptr(pDel)); - assert( cmp( *node_traits::to_value_ptr( pDel ), val ) == 0 ); - - unsigned int nHeight = pDel->height(); - if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { - --m_ItemCounter; - m_Stat.onRemoveNode( nHeight ); - m_Stat.onExtractSuccess(); - return true; - } - - m_Stat.onExtractRetry(); - } - } - - bool extract_min_( typename gc::Guard& gDel ) - { - position pos; - - for (;;) { - if ( !find_min_position( pos ) ) { - // The list is empty - m_Stat.onExtractMinFailed(); - return false; - } - - node_type * pDel = pos.pCur; - - unsigned int nHeight = pDel->height(); - gDel.assign( node_traits::to_value_ptr(pDel) ); - - if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { - --m_ItemCounter; - m_Stat.onRemoveNode( nHeight ); - m_Stat.onExtractMinSuccess(); - return true; - } - - m_Stat.onExtractMinRetry(); - } - } - - bool extract_max_( typename gc::Guard& gDel ) - { - position pos; - - for (;;) { - if ( !find_max_position( pos ) ) { - // The list is empty - m_Stat.onExtractMaxFailed(); - return false; - } - - node_type * pDel = pos.pCur; - - unsigned int nHeight = pDel->height(); - gDel.assign( node_traits::to_value_ptr(pDel) ); - - if ( try_remove_at( pDel, pos, [](value_type const&) {} )) { - --m_ItemCounter; - m_Stat.onRemoveNode( nHeight ); - m_Stat.onExtractMaxSuccess(); - return true; - } - - m_Stat.onExtractMaxRetry(); - } - } - - void increase_height( unsigned int nHeight ) - { - unsigned int nCur = m_nHeight.load( memory_model::memory_order_relaxed ); - if ( nCur < nHeight ) - m_nHeight.compare_exchange_strong( nCur, nHeight, memory_model::memory_order_release, atomics::memory_order_relaxed ); - } - //@endcond - - public: - /// Default constructor - /** - The constructor checks whether the count of guards is enough - for skip-list and may raise an exception if not. - */ - SkipListSet() - : m_Head( c_nMaxHeight ) - , m_nHeight( c_nMinHeight ) - { - static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" ); - - gc::check_available_guards( c_nHazardPtrCount ); - - // Barrier for head node - atomics::atomic_thread_fence( memory_model::memory_order_release ); - } - - /// Clears and destructs the skip-list - ~SkipListSet() - { - clear(); - } - - public: - /// Iterator type - typedef skip_list::details::iterator< gc, node_traits, back_off, false > iterator; - - /// Const iterator type - typedef skip_list::details::iterator< gc, node_traits, back_off, true > const_iterator; - - /// Returns a forward iterator addressing the first element in a set - iterator begin() - { - return iterator( *m_Head.head() ); - } - - /// Returns a forward const iterator addressing the first element in a set - //@{ - const_iterator begin() const - { - return const_iterator( *m_Head.head() ); - } - const_iterator cbegin() - { - return const_iterator( *m_Head.head() ); - } - //@} - - /// Returns a forward iterator that addresses the location succeeding the last element in a set. - iterator end() - { - return iterator(); - } - - /// Returns a forward const iterator that addresses the location succeeding the last element in a set. - //@{ - const_iterator end() const - { - return const_iterator(); - } - const_iterator cend() - { - return const_iterator(); - } - //@} - - public: - /// Inserts new node - /** - The function inserts \p val in the set if it does not contain - an item with key equal to \p val. - - Returns \p true if \p val is placed into the set, \p false otherwise. - */ - bool insert( value_type& val ) - { - return insert( val, []( value_type& ) {} ); - } - - /// Inserts new node - /** - This function is intended for derived non-intrusive containers. - - The function allows to split creating of new item into two part: - - create item with key only - - insert new item into the set - - if inserting is success, calls \p f functor to initialize value-field of \p val. - - The functor signature is: - \code - void func( value_type& val ); - \endcode - where \p val is the item inserted. User-defined functor \p f should guarantee that during changing - \p val no any other changes could be made on this set's item by concurrent threads. - The user-defined functor is called only if the inserting is success and may be passed by reference - using boost::ref - */ - template - bool insert( value_type& val, Func f ) - { - typename gc::Guard gNew; - gNew.assign( &val ); - - node_type * pNode = node_traits::to_node_ptr( val ); - scoped_node_ptr scp( pNode ); - unsigned int nHeight = pNode->height(); - bool bTowerOk = nHeight > 1 && pNode->get_tower() != nullptr; - bool bTowerMade = false; - - position pos; - while ( true ) - { - bool bFound = find_position( val, pos, key_comparator(), true ); - if ( bFound ) { - // scoped_node_ptr deletes the node tower if we create it - if ( !bTowerMade ) - scp.release(); - - m_Stat.onInsertFailed(); - return false; - } - - if ( !bTowerOk ) { - build_node( pNode ); - nHeight = pNode->height(); - bTowerMade = - bTowerOk = true; - } - - if ( !insert_at_position( val, pNode, pos, f )) { - m_Stat.onInsertRetry(); - continue; - } - - increase_height( nHeight ); - ++m_ItemCounter; - m_Stat.onAddNode( nHeight ); - m_Stat.onInsertSuccess(); - scp.release(); - return true; - } - } - - /// Ensures that the \p val exists in the set - /** - The operation performs inserting or changing data with lock-free manner. - - If the item \p val is not found in the set, then \p val is inserted into the set. - Otherwise, the functor \p func is called with item found. - The functor signature is: - \code - void func( bool bNew, value_type& item, value_type& 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 val passed into the \p ensure function - If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments - refer to the same thing. - - The functor can change non-key fields of the \p item; however, \p func must guarantee - that during changing no any other modifications could be made on this item by concurrent threads. - - You can pass \p func argument by value or by reference using boost::ref or cds::ref. - - Returns std::pair where \p first is \p true if operation is successfull, - \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. - */ - template - std::pair ensure( value_type& val, Func func ) - { - typename gc::Guard gNew; - gNew.assign( &val ); - - node_type * pNode = node_traits::to_node_ptr( val ); - scoped_node_ptr scp( pNode ); - unsigned int nHeight = pNode->height(); - bool bTowerOk = nHeight > 1 && pNode->get_tower() != nullptr; - bool bTowerMade = false; - - position pos; - while ( true ) - { - bool bFound = find_position( val, pos, key_comparator(), true ); - if ( bFound ) { - // scoped_node_ptr deletes the node tower if we create it before - if ( !bTowerMade ) - scp.release(); - - cds::unref(func)( false, *node_traits::to_value_ptr(pos.pCur), val ); - m_Stat.onEnsureExist(); - return std::make_pair( true, false ); - } - - if ( !bTowerOk ) { - build_node( pNode ); - nHeight = pNode->height(); - bTowerMade = - bTowerOk = true; - } - - if ( !insert_at_position( val, pNode, pos, [&func]( value_type& item ) { cds::unref(func)( true, item, item ); })) { - m_Stat.onInsertRetry(); - continue; - } - - increase_height( nHeight ); - ++m_ItemCounter; - scp.release(); - m_Stat.onAddNode( nHeight ); - m_Stat.onEnsureNew(); - return std::make_pair( true, true ); - } - } - - /// Unlinks the item \p val from the set - /** - The function searches the item \p val in the set and unlink it from the set - if it is found and is equal to \p val. - - Difference between \ref erase and \p unlink functions: \p erase finds a key - and deletes the item found. \p unlink finds an item by key and deletes it - only if \p val is an item of that set, i.e. the pointer to item found - is equal to &val . - - The \ref disposer specified in \p Traits class template parameter is called - by garbage collector \p GC asynchronously. - - The function returns \p true if success and \p false otherwise. - */ - bool unlink( value_type& val ) - { - position pos; - - if ( !find_position( val, pos, key_comparator(), false ) ) { - m_Stat.onUnlinkFailed(); - return false; - } - - node_type * pDel = pos.pCur; - assert( key_comparator()( *node_traits::to_value_ptr( pDel ), val ) == 0 ); - - unsigned int nHeight = pDel->height(); - typename gc::Guard gDel; - gDel.assign( node_traits::to_value_ptr(pDel) ); - - if ( node_traits::to_value_ptr( pDel ) == &val && try_remove_at( pDel, pos, [](value_type const&) {} )) { - --m_ItemCounter; - m_Stat.onRemoveNode( nHeight ); - m_Stat.onUnlinkSuccess(); - return true; - } - - m_Stat.onUnlinkFailed(); - return false; - } - - /// Extracts the item from the set with specified \p key - /** \anchor cds_intrusive_SkipListSet_hp_extract - The function searches an item with key equal to \p key in the set, - unlinks it from the set, and returns it in \p dest parameter. - If the item with key equal to \p key is not found the function returns \p false. - - Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. - - The \ref disposer specified in \p Traits class template parameter is called automatically - by garbage collector \p GC specified in class' template parameters when returned \ref guarded_ptr object - will be destroyed or released. - @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. - - Usage: - \code - typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; - skip_list theList; - // ... - { - skip_list::guarded_ptr gp; - theList.extract( gp, 5 ); - // Deal with gp - // ... - - // Destructor of gp releases internal HP guard - } - \endcode - */ - template - bool extract( guarded_ptr& dest, Q const& key ) - { - return extract_( dest.guard(), key, key_comparator() ); - } - - /// Extracts the item from the set with comparing functor \p pred - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_extract "extract(Q const&)" - but \p pred predicate is used for key comparing. - - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool extract_with( guarded_ptr& dest, Q const& key, Less pred ) - { - return extract_( dest.guard(), key, cds::opt::details::make_comparator_from_less() ); - } - - /// Extracts an item with minimal key from the list - /** - The function searches an item with minimal key, unlinks it, and returns the item found in \p dest parameter. - If the skip-list is empty the function returns \p false. - - @note Due the concurrent nature of the list, the function extracts nearly minimum key. - It means that the function gets leftmost item and tries to unlink it. - During unlinking, a concurrent thread may insert an item with key less than leftmost item's key. - So, the function returns the item with minimum key at the moment of list traversing. - - The \ref disposer specified in \p Traits class template parameter is called - by garbage collector \p GC automatically when returned \ref guarded_ptr object - will be destroyed or released. - @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. - - Usage: - \code - typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; - skip_list theList; - // ... - { - skip_list::guarded_ptr gp; - if ( theList.extract_min( gp )) { - // Deal with gp - //... - } - // Destructor of gp releases internal HP guard - } - \endcode - */ - bool extract_min( guarded_ptr& dest) - { - return extract_min_( dest.guard() ); - } - - /// Extracts an item with maximal key from the list - /** - The function searches an item with maximal key, unlinks it, and returns the pointer to item found in \p dest parameter. - If the skip-list is empty the function returns empty \p guarded_ptr. - - @note Due the concurrent nature of the list, the function extracts nearly maximal key. - It means that the function gets rightmost item and tries to unlink it. - During unlinking, a concurrent thread may insert an item with key greater than rightmost item's key. - So, the function returns the item with maximum key at the moment of list traversing. - - The \ref disposer specified in \p Traits class template parameter is called - by garbage collector \p GC asynchronously when returned \ref guarded_ptr object - will be destroyed or released. - @note Each \p guarded_ptr object uses the GC's guard that can be limited resource. - - Usage: - \code - typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; - skip_list theList; - // ... - { - skip_list::guarded_ptr gp; - if ( theList.extract_max( gp )) { - // Deal with gp - //... - } - // Destructor of gp releases internal HP guard - } - \endcode - */ - bool extract_max( guarded_ptr& dest ) - { - return extract_max_( dest.guard() ); - } - - /// Deletes the item from the set - /** \anchor cds_intrusive_SkipListSet_hp_erase - The function searches an item with key equal to \p val in the set, - unlinks it from the set, and returns \p true. - If the item with key equal to \p val is not found the function return \p false. - - Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. - */ - template - bool erase( Q const& val ) - { - return erase_( val, key_comparator(), [](value_type const&) {} ); - } - - /// Deletes the item from the set with comparing functor \p pred - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_erase "erase(Q const&)" - but \p pred predicate is used for key comparing. - - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool erase_with( Q const& val, Less pred ) - { - return erase_( val, cds::opt::details::make_comparator_from_less(), [](value_type const&) {} ); - } - - /// Deletes the item from the set - /** \anchor cds_intrusive_SkipListSet_hp_erase_func - The function searches an item with key equal to \p val in the set, - call \p f functor with item found, unlinks it from the set, and returns \p true. - The \ref disposer specified in \p Traits class template parameter is called - by garbage collector \p GC asynchronously. - - The \p Func interface is - \code - struct functor { - void operator()( value_type const& item ); - }; - \endcode - The functor can be passed by reference with boost:ref - - If the item with key equal to \p val is not found the function return \p false. - - Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type. - */ - template - bool erase( Q const& val, Func f ) - { - return erase_( val, key_comparator(), f ); - } - - /// Deletes the item from the set with comparing functor \p pred - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_erase_func "erase(Q const&, Func)" - but \p pred predicate is used for key comparing. - - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool erase_with( Q const& val, Less pred, Func f ) - { - return erase_( val, cds::opt::details::make_comparator_from_less(), f ); - } - - /// Finds the key \p val - /** \anchor cds_intrusive_SkipListSet_hp_find_func - The function searches the item with key equal to \p val and calls the functor \p f for item found. - The interface of \p Func functor is: - \code - struct functor { - void operator()( value_type& item, Q& val ); - }; - \endcode - where \p item is the item found, \p val is the find function argument. - - You can pass \p f argument by value or by reference using boost::ref or cds::ref. - - The functor can change non-key fields of \p item. Note that the functor is only guarantee - that \p item cannot be disposed during functor is executing. - The functor does not serialize simultaneous access to the set \p item. If such access is - possible you must provide your own synchronization schema on item level to exclude unsafe item modifications. - - The \p val argument is non-const since it can be used as \p f functor destination i.e., the functor - can modify both arguments. - - Note the compare functor specified for class \p Traits template parameter - should accept a parameter of type \p Q that can be not the same as \p value_type. - - The function returns \p true if \p val is found, \p false otherwise. - */ - template - bool find( Q& val, Func f ) - { - return find_with_( val, key_comparator(), f ); - } - - /// Finds the key \p val with \p pred predicate for comparing - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_func "find(Q&, Func)" - but \p pred is used for key compare. - - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool find_with( Q& val, Less pred, Func f ) - { - return find_with_( val, cds::opt::details::make_comparator_from_less(), f ); - } - - /// Finds the key \p val - /** \anchor cds_intrusive_SkipListSet_hp_find_cfunc - The function searches the item with key equal to \p val and calls the functor \p f for item found. - The interface of \p Func functor is: - \code - struct functor { - void operator()( value_type& item, Q const& val ); - }; - \endcode - where \p item is the item found, \p val is the find function argument. - - You can pass \p f argument by value or by reference using boost::ref or cds::ref. - - The functor can change non-key fields of \p item. Note that the functor is only guarantee - that \p item cannot be disposed during functor is executing. - The functor does not serialize simultaneous access to the set \p item. If such access is - possible you must provide your own synchronization schema on item level to exclude unsafe item modifications. - - Note the compare functor specified for class \p Traits template parameter - should accept a parameter of type \p Q that can be not the same as \p value_type. - - The function returns \p true if \p val is found, \p false otherwise. - */ - template - bool find( Q const& val, Func f ) - { - return find_with_( val, key_comparator(), f ); - } - - /// Finds the key \p val with \p pred predicate for comparing - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_cfunc "find(Q const&, Func)" - but \p pred is used for key compare. - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool find_with( Q const& val, Less pred, Func f ) - { - return find_with_( val, cds::opt::details::make_comparator_from_less(), f ); - } - - /// Finds the key \p val - /** \anchor cds_intrusive_SkipListSet_hp_find_val - The function searches the item with key equal to \p val - and returns \p true if it is found, and \p false otherwise. - - Note the compare functor specified for class \p Traits template parameter - should accept a parameter of type \p Q that can be not the same as \p value_type. - */ - template - bool find( Q const & val ) - { - return find_with_( val, key_comparator(), [](value_type& , Q const& ) {} ); - } - - /// Finds the key \p val with comparing functor \p pred - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_find_val "find(Q const&)" - but \p pred is used for comparing the keys. - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool find_with( Q const& val, Less pred ) - { - return find_with_( val, cds::opt::details::make_comparator_from_less(), [](value_type& , Q const& ) {} ); - } - - /// Finds the key \p val and return the item found - /** \anchor cds_intrusive_SkipListSet_hp_get - The function searches the item with key equal to \p val - and assigns the item found to guarded pointer \p ptr. - The function returns \p true if \p val is found, and \p false otherwise. - If \p val is not found the \p ptr parameter is not changed. - - The \ref disposer specified in \p Traits class template parameter is called - by garbage collector \p GC asynchronously when returned \ref guarded_ptr object - will be destroyed or released. - @note Each \p guarded_ptr object uses one GC's guard which can be limited resource. - - Usage: - \code - typedef cds::intrusive::SkipListSet< cds::gc::HP, foo, my_traits > skip_list; - skip_list theList; - // ... - { - skip_list::guarded_ptr gp; - if ( theList.get( gp, 5 )) { - // Deal with gp - //... - } - // Destructor of guarded_ptr releases internal HP guard - } - \endcode - - Note the compare functor specified for class \p Traits template parameter - should accept a parameter of type \p Q that can be not the same as \p value_type. - */ - template - bool get( guarded_ptr& ptr, Q const& val ) - { - return get_with_( ptr.guard(), val, key_comparator() ); - } - - /// Finds the key \p val and return the item found - /** - The function is an analog of \ref cds_intrusive_SkipListSet_hp_get "get( guarded_ptr& ptr, Q const&)" - but \p pred is used for comparing the keys. - - \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q - in any order. - \p pred must imply the same element order as the comparator used for building the set. - */ - template - bool get_with( guarded_ptr& ptr, Q const& val, Less pred ) - { - return get_with_( ptr.guard(), val, cds::opt::details::make_comparator_from_less() ); - } - - /// Returns item count in the set - /** - The value returned depends on item counter type provided by \p Traits template parameter. - If it is atomicity::empty_item_counter this function always returns 0. - Therefore, the function is not suitable for checking the set emptiness, use \ref empty - member function for this purpose. - */ - size_t size() const - { - return m_ItemCounter; - } - - /// Checks if the set is empty - bool empty() const - { - return m_Head.head()->next( 0 ).load( memory_model::memory_order_relaxed ) == nullptr; - } - - /// Clears the set (non-atomic) - /** - The function unlink all items from the set. - The function is not atomic, i.e., in multi-threaded environment with parallel insertions - this sequence - \code - set.clear(); - assert( set.empty() ); - \endcode - the assertion could be raised. - - For each item the \ref disposer will be called after unlinking. - */ - void clear() - { - guarded_ptr gp; - while ( extract_min( gp )); - } - - /// Returns maximum height of skip-list. The max height is a constant for each object and does not exceed 32. - static CDS_CONSTEXPR unsigned int max_height() CDS_NOEXCEPT - { - return c_nMaxHeight; - } - - /// Returns const reference to internal statistics - stat const& statistics() const - { - return m_Stat; - } - - }; - -}} // namespace cds::intrusive - - -#endif // #ifndef __CDS_INTRUSIVE_SKIP_LIST_IMPL_H diff --git a/cds/intrusive/skip_list_ptb.h b/cds/intrusive/skip_list_ptb.h index 09acb138..87a5f9aa 100644 --- a/cds/intrusive/skip_list_ptb.h +++ b/cds/intrusive/skip_list_ptb.h @@ -4,6 +4,6 @@ #define __CDS_INTRUSIVE_SKIP_LIST_PTB_H #include -#include +#include #endif diff --git a/projects/Win/vc12/cds.vcxproj b/projects/Win/vc12/cds.vcxproj index 71c00816..a415fb6e 100644 --- a/projects/Win/vc12/cds.vcxproj +++ b/projects/Win/vc12/cds.vcxproj @@ -752,6 +752,7 @@ + @@ -759,7 +760,6 @@ - diff --git a/projects/Win/vc12/cds.vcxproj.filters b/projects/Win/vc12/cds.vcxproj.filters index 7be01398..5bf5b4df 100644 --- a/projects/Win/vc12/cds.vcxproj.filters +++ b/projects/Win/vc12/cds.vcxproj.filters @@ -959,9 +959,6 @@ Header Files\cds\intrusive - - Header Files\cds\intrusive - Header Files\cds\intrusive @@ -1280,5 +1277,8 @@ Header Files\cds\intrusive\details + + Header Files\cds\intrusive\impl + \ No newline at end of file