Source code repo: http://github.com/khizmax/libcds/
Download: http://sourceforge.net/projects/libcds/files/
-
+
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
/** @ingroup cds_intrusive_list
\anchor cds_intrusive_IterableList_hp
- This lock-free list implementation supports thread-safe iterators.
+ This non-blocking list implementation supports thread-safe iterators;
+ searching and removing are lock-free, inserting is non-blocking because it
+ uses a light-weight synchronization based on marked pointers.
+
Unlike \p cds::intrusive::MichaelList the iterable list does not require
any hook in \p T to be stored in the list.
typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
- static CDS_CONSTEXPR const size_t c_nHazardPtrCount = 2; ///< Count of hazard pointer required for the algorithm
+ static CDS_CONSTEXPR const size_t c_nHazardPtrCount = 3; ///< Count of hazard pointer required for the algorithm
//@cond
// Rebind traits (split-list support)
//@endcond
protected:
+ //@cond
typedef atomics::atomic< node_type* > atomic_node_ptr; ///< Atomic node pointer
typedef atomic_node_ptr auxiliary_head; ///< Auxiliary head type (for split-list support)
+ typedef typename node_type::marked_data_ptr marked_data_ptr;
+
+ node_type m_Head;
+ node_type m_Tail;
- atomic_node_ptr m_pHead; ///< Head pointer
item_counter m_ItemCounter; ///< Item counter
mutable stat m_Stat; ///< Internal statistics
- //@cond
typedef cds::details::Allocator< node_type, node_allocator > cxx_node_allocator;
/// Position pointer for item search
struct position {
- atomic_node_ptr * pHead; ///< Previous node (pointer to pPrev->next or to m_pHead)
+ node_type const* pHead;
node_type * pPrev; ///< Previous node
node_type * pCur; ///< Current node
- value_type * pFound; ///< Value of \p pCur->data, valid only if data found
- typename gc::Guard guard; ///< guard for \p pFound
+ value_type * pFound; ///< Value of \p pCur->data, valid only if data found
+
+ typename gc::Guard guard; ///< guard for \p pFound
+ };
+
+ struct insert_position: public position
+ {
+ value_type * pPrevVal; ///< Value of \p pPrev->data, can be \p nullptr
+ typename gc::Guard prevGuard; ///< guard for \p pPrevVal
};
//@endcond
friend class IterableList;
protected:
- node_type* m_pNode;
+ node_type const* m_pNode;
typename gc::Guard m_Guard; // data guard
void next()
{
- while ( m_pNode ) {
- m_pNode = m_pNode->next.load( memory_model::memory_order_acquire );
- if ( !m_pNode ) {
- m_Guard.clear();
- break;
- }
- if ( m_Guard.protect( m_pNode->data ))
- break;
+ for ( node_type* p = m_pNode->next.load( memory_model::memory_order_relaxed ); p != m_pNode; p = p->next.load( memory_model::memory_order_relaxed ))
+ {
+ m_pNode = p;
+ if ( m_Guard.protect( p->data, []( marked_data_ptr p ) { return p.ptr(); }).ptr())
+ return;
}
+ m_Guard.clear();
}
- explicit iterator_type( atomic_node_ptr const& pNode )
- : m_pNode( pNode.load( memory_model::memory_order_acquire ))
+ explicit iterator_type( node_type const* pNode )
+ : m_pNode( pNode )
{
- if ( m_pNode ) {
- if ( !m_Guard.protect( m_pNode->data ))
- next();
- }
+ if ( !m_Guard.protect( pNode->data, []( marked_data_ptr p ) { return p.ptr(); }).ptr())
+ next();
}
- iterator_type( node_type* pNode, value_type* pVal )
+ iterator_type( node_type const* pNode, value_type* pVal )
: m_pNode( pNode )
{
if ( m_pNode ) {
value_ptr operator ->() const
{
- return m_Guard.get<value_type>();
+ return m_Guard.template get<value_type>();
}
value_ref operator *() const
{
assert( m_Guard.get_native() != nullptr );
- return *m_Guard.get<value_type>();
+ return *m_Guard.template get<value_type>();
}
/// Pre-increment
*/
iterator begin()
{
- return iterator( m_pHead );
+ return iterator( &m_Head );
}
/// Returns an iterator that addresses the location succeeding the last element in a list
*/
iterator end()
{
- return iterator();
+ return iterator( &m_Tail );
}
/// Returns a forward const iterator addressing the first element in a list
const_iterator cbegin() const
{
- return const_iterator( m_pHead );
+ return const_iterator( &m_Head );
}
/// Returns a forward const iterator addressing the first element in a list
const_iterator begin() const
{
- return const_iterator( m_pHead );
+ return const_iterator( &m_Head );
}
/// Returns an const iterator that addresses the location succeeding the last element in a list
const_iterator end() const
{
- return const_iterator();
+ return const_iterator( &m_Tail );
}
/// Returns an const iterator that addresses the location succeeding the last element in a list
const_iterator cend() const
{
- return const_iterator();
+ return const_iterator( &m_Tail );
}
//@}
public:
/// Default constructor initializes empty list
IterableList()
- : m_pHead( nullptr )
- {}
+ {
+ init_list();
+ }
//@cond
template <typename Stat, typename = std::enable_if<std::is_same<stat, iterable_list::wrapped_stat<Stat>>::value >>
explicit IterableList( Stat& st )
- : m_pHead( nullptr )
- , m_Stat( st )
- {}
+ : m_Stat( st )
+ {
+ init_list();
+ }
//@endcond
/// Destroys the list object
*/
bool insert( value_type& val )
{
- return insert_at( m_pHead, val );
+ return insert_at( &m_Head, val );
}
/// Inserts new node
template <typename Func>
bool insert( value_type& val, Func f )
{
- return insert_at( m_pHead, val, f );
+ return insert_at( &m_Head, val, f );
}
/// Updates the node
template <typename Func>
std::pair<bool, bool> update( value_type& val, Func func, bool bInsert = true )
{
- return update_at( m_pHead, val, func, bInsert );
+ return update_at( &m_Head, val, func, bInsert );
}
/// Insert or update
*/
std::pair<bool, bool> upsert( value_type& val, bool bInsert = true )
{
- return update_at( m_pHead, val, []( value_type&, value_type* ) {}, bInsert );
+ return update_at( &m_Head, val, []( value_type&, value_type* ) {}, bInsert );
}
/// Unlinks the item \p val from the list
*/
bool unlink( value_type& val )
{
- return unlink_at( m_pHead, val );
+ return unlink_at( &m_Head, val );
}
/// Deletes the item from the list
template <typename Q>
bool erase( Q const& key )
{
- return erase_at( m_pHead, key, key_comparator());
+ return erase_at( &m_Head, key, key_comparator());
}
/// Deletes the item from the list using \p pred predicate for searching
bool erase_with( Q const& key, Less pred )
{
CDS_UNUSED( pred );
- return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
+ return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Deletes the item from the list
template <typename Q, typename Func>
bool erase( Q const& key, Func func )
{
- return erase_at( m_pHead, key, key_comparator(), func );
+ return erase_at( &m_Head, key, key_comparator(), func );
}
/// Deletes the item from the list using \p pred predicate for searching
bool erase_with( Q const& key, Less pred, Func f )
{
CDS_UNUSED( pred );
- return erase_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
+ return erase_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
}
/// Extracts the item from the list with specified \p key
ord_list theList;
// ...
{
- ord_list::guarded_ptr gp(theList.extract( 5 ));
+ ord_list::guarded_ptr gp( theList.extract( 5 ));
if ( gp ) {
// Deal with gp
// ...
template <typename Q>
guarded_ptr extract( Q const& key )
{
- guarded_ptr gp;
- extract_at( m_pHead, gp.guard(), key, key_comparator());
- return gp;
+ return extract_at( &m_Head, key, key_comparator());
}
/// Extracts the item using compare functor \p pred
guarded_ptr extract_with( Q const& key, Less pred )
{
CDS_UNUSED( pred );
- guarded_ptr gp;
- extract_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
- return gp;
+ return extract_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Finds \p key in the list
template <typename Q, typename Func>
bool find( Q& key, Func f ) const
{
- return find_at( m_pHead, key, key_comparator(), f );
+ return find_at( &m_Head, key, key_comparator(), f );
}
//@cond
template <typename Q, typename Func>
bool find( Q const& key, Func f ) const
{
- return find_at( m_pHead, key, key_comparator(), f );
+ return find_at( &m_Head, key, key_comparator(), f );
}
//@endcond
template <typename Q>
iterator find( Q const& key ) const
{
- return find_iterator_at( m_pHead, key, key_comparator());
+ return find_iterator_at( &m_Head, key, key_comparator());
}
/// Finds the \p key using \p pred predicate for searching
bool find_with( Q& key, Less pred, Func f ) const
{
CDS_UNUSED( pred );
- return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
+ return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
}
//@cond
template <typename Q, typename Less, typename Func>
bool find_with( Q const& key, Less pred, Func f ) const
{
CDS_UNUSED( pred );
- return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>(), f );
+ return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>(), f );
}
//@endcond
iterator find_with( Q const& key, Less pred ) const
{
CDS_UNUSED( pred );
- return find_iterator_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
+ return find_iterator_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Checks whether the list contains \p key
template <typename Q>
bool contains( Q const& key ) const
{
- return find_at( m_pHead, key, key_comparator());
+ return find_at( &m_Head, key, key_comparator());
}
/// Checks whether the list contains \p key using \p pred predicate for searching
bool contains( Q const& key, Less pred ) const
{
CDS_UNUSED( pred );
- return find_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
+ return find_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Finds the \p key and return the item found
template <typename Q>
guarded_ptr get( Q const& key ) const
{
- guarded_ptr gp;
- get_at( m_pHead, gp.guard(), key, key_comparator());
- return gp;
+ return get_at( &m_Head, key, key_comparator());
}
/// Finds the \p key and return the item found
guarded_ptr get_with( Q const& key, Less pred ) const
{
CDS_UNUSED( pred );
- guarded_ptr gp;
- get_at( m_pHead, gp.guard(), key, cds::opt::details::make_comparator_from_less<Less>());
- return gp;
+ return get_at( &m_Head, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Clears the list (thread safe, not atomic)
void clear()
{
position pos;
- for ( pos.pCur = m_pHead.load( memory_model::memory_order_relaxed ); pos.pCur; pos.pCur = pos.pCur->next.load( memory_model::memory_order_relaxed )) {
+ pos.pPrev = nullptr;
+ for ( pos.pCur = m_Head.next.load( memory_model::memory_order_relaxed ); pos.pCur != pos.pPrev; pos.pCur = pos.pCur->next.load( memory_model::memory_order_relaxed )) {
while ( true ) {
- pos.pFound = pos.guard.protect( pos.pCur->data );
+ pos.pFound = pos.guard.protect( pos.pCur->data, []( marked_data_ptr p ) { return p.ptr(); }).ptr();
if ( !pos.pFound )
break;
- if ( cds_likely( unlink_node( pos ))) {
+ if ( cds_likely( unlink_data( pos ))) {
--m_ItemCounter;
break;
}
}
+ pos.pPrev = pos.pCur;
}
}
// split-list support
bool insert_aux_node( node_type * pNode )
{
- return insert_aux_node( m_pHead, pNode );
+ return insert_aux_node( &m_Head, pNode );
}
// split-list support
- bool insert_aux_node( atomic_node_ptr& refHead, node_type * pNode )
+ bool insert_aux_node( node_type* pHead, node_type * pNode )
{
assert( pNode != nullptr );
// Hack: convert node_type to value_type.
// In principle, auxiliary node can be non-reducible to value_type
// We assume that comparator can correctly distinguish aux and regular node.
- return insert_at( refHead, *node_traits::to_value_ptr( pNode ) );
+ return insert_at( pHead, *node_traits::to_value_ptr( pNode ) );
}
#endif
- bool insert_at( atomic_node_ptr& refHead, value_type& val )
+ bool insert_at( node_type* pHead, value_type& val )
{
- position pos;
+ insert_position pos;
while ( true ) {
- if ( search( refHead, val, pos, key_comparator() )) {
+ if ( inserting_search( pHead, val, pos, key_comparator() )) {
m_Stat.onInsertFailed();
return false;
}
- if ( link_node( &val, pos ) ) {
+ if ( link_data( &val, pos ) ) {
++m_ItemCounter;
m_Stat.onInsertSuccess();
return true;
}
template <typename Func>
- bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
+ bool insert_at( node_type* pHead, value_type& val, Func f )
{
- position pos;
+ insert_position pos;
typename gc::Guard guard;
guard.assign( &val );
while ( true ) {
- if ( search( refHead, val, pos, key_comparator() ) ) {
+ if ( inserting_search( pHead, val, pos, key_comparator() ) ) {
m_Stat.onInsertFailed();
return false;
}
- if ( link_node( &val, pos ) ) {
+ if ( link_data( &val, pos ) ) {
f( val );
++m_ItemCounter;
m_Stat.onInsertSuccess();
}
template <typename Func>
- std::pair<bool, bool> update_at( atomic_node_ptr& refHead, value_type& val, Func func, bool bInsert )
+ std::pair<bool, bool> update_at( node_type* pHead, value_type& val, Func func, bool bInsert )
{
- position pos;
+ insert_position pos;
typename gc::Guard guard;
guard.assign( &val );
while ( true ) {
- if ( search( refHead, val, pos, key_comparator() ) ) {
+ if ( inserting_search( pHead, val, pos, key_comparator() ) ) {
// try to replace pCur->data with val
assert( pos.pFound != nullptr );
assert( key_comparator()(*pos.pFound, val) == 0 );
- if ( cds_likely( pos.pCur->data.compare_exchange_strong( pos.pFound, &val, memory_model::memory_order_release, atomics::memory_order_relaxed ))) {
+ marked_data_ptr pFound( pos.pFound );
+ if ( cds_likely( pos.pCur->data.compare_exchange_strong( pFound, marked_data_ptr( &val ),
+ memory_model::memory_order_release, atomics::memory_order_relaxed )))
+ {
if ( pos.pFound != &val ) {
retire_data( pos.pFound );
func( val, pos.pFound );
return std::make_pair( false, false );
}
- if ( link_node( &val, pos )) {
+ if ( link_data( &val, pos )) {
func( val, static_cast<value_type*>( nullptr ));
++m_ItemCounter;
m_Stat.onUpdateNew();
}
}
- bool unlink_at( atomic_node_ptr& refHead, value_type& val )
+ bool unlink_at( node_type* pHead, value_type& val )
{
position pos;
back_off bkoff;
- while ( search( refHead, val, pos, key_comparator())) {
+ while ( search( pHead, val, pos, key_comparator())) {
if ( pos.pFound == &val ) {
- if ( unlink_node( pos )) {
+ if ( unlink_data( pos )) {
--m_ItemCounter;
m_Stat.onEraseSuccess();
return true;
}
template <typename Q, typename Compare, typename Func>
- bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f, position& pos )
+ bool erase_at( node_type* pHead, const Q& val, Compare cmp, Func f, position& pos )
{
back_off bkoff;
- while ( search( refHead, val, pos, cmp )) {
- if ( unlink_node( pos )) {
+ while ( search( pHead, val, pos, cmp )) {
+ if ( unlink_data( pos )) {
f( *pos.pFound );
--m_ItemCounter;
m_Stat.onEraseSuccess();
}
template <typename Q, typename Compare, typename Func>
- bool erase_at( atomic_node_ptr& refHead, const Q& val, Compare cmp, Func f )
+ bool erase_at( node_type* pHead, const Q& val, Compare cmp, Func f )
{
position pos;
- return erase_at( refHead, val, cmp, f, pos );
+ return erase_at( pHead, val, cmp, f, pos );
}
template <typename Q, typename Compare>
- bool erase_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
+ bool erase_at( node_type* pHead, Q const& val, Compare cmp )
{
position pos;
- return erase_at( refHead, val, cmp, [](value_type const&){}, pos );
+ return erase_at( pHead, val, cmp, [](value_type const&){}, pos );
}
template <typename Q, typename Compare>
- bool extract_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& dest, Q const& val, Compare cmp )
+ guarded_ptr extract_at( node_type* pHead, Q const& val, Compare cmp )
{
position pos;
back_off bkoff;
- while ( search( refHead, val, pos, cmp )) {
- if ( unlink_node( pos )) {
- dest.set( pos.pFound );
+ while ( search( pHead, val, pos, cmp )) {
+ if ( unlink_data( pos )) {
--m_ItemCounter;
m_Stat.onEraseSuccess();
- return true;
+ assert( pos.pFound != nullptr );
+ return guarded_ptr( std::move( pos.guard ));
}
else
bkoff();
}
m_Stat.onEraseFailed();
- return false;
+ return guarded_ptr();
}
template <typename Q, typename Compare>
- bool find_at( atomic_node_ptr const& refHead, Q const& val, Compare cmp ) const
+ bool find_at( node_type const* pHead, Q const& val, Compare cmp ) const
{
position pos;
- if ( search( refHead, val, pos, cmp ) ) {
+ if ( search( pHead, val, pos, cmp ) ) {
m_Stat.onFindSuccess();
return true;
}
}
template <typename Q, typename Compare, typename Func>
- bool find_at( atomic_node_ptr const& refHead, Q& val, Compare cmp, Func f ) const
+ bool find_at( node_type const* pHead, Q& val, Compare cmp, Func f ) const
{
position pos;
- if ( search( refHead, val, pos, cmp )) {
+ if ( search( pHead, val, pos, cmp )) {
assert( pos.pFound != nullptr );
f( *pos.pFound, val );
m_Stat.onFindSuccess();
}
template <typename Q, typename Compare>
- iterator find_iterator_at( atomic_node_ptr const& refHead, Q const& val, Compare cmp ) const
+ iterator find_iterator_at( node_type const* pHead, Q const& val, Compare cmp ) const
{
position pos;
- if ( search( refHead, val, pos, cmp )) {
+ if ( search( pHead, val, pos, cmp )) {
assert( pos.pCur != nullptr );
assert( pos.pFound != nullptr );
m_Stat.onFindSuccess();
}
m_Stat.onFindFailed();
- return iterator{};
+ return iterator( &m_Tail );
}
template <typename Q, typename Compare>
- bool get_at( atomic_node_ptr const& refHead, typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp ) const
+ guarded_ptr get_at( node_type const* pHead, Q const& val, Compare cmp ) const
{
position pos;
- if ( search( refHead, val, pos, cmp )) {
- guard.set( pos.pFound );
+ if ( search( pHead, val, pos, cmp )) {
m_Stat.onFindSuccess();
- return true;
+ return guarded_ptr( std::move( pos.guard ));
}
m_Stat.onFindFailed();
- return false;
+ return guarded_ptr();
+ }
+
+ node_type* head()
+ {
+ return &m_Head;
+ }
+
+ node_type const* head() const
+ {
+ return &m_Head;
}
//@endcond
protected:
-
//@cond
template <typename Q, typename Compare >
- bool search( atomic_node_ptr const& refHead, const Q& val, position& pos, Compare cmp ) const
+ bool search( node_type const* pHead, Q const& val, position& pos, Compare cmp ) const
{
- atomic_node_ptr* pHead = const_cast<atomic_node_ptr*>( &refHead );
- node_type * pPrev = nullptr;
+ pos.pHead = pHead;
+ node_type* pPrev = const_cast<node_type*>( pHead );
while ( true ) {
- node_type * pCur = pHead->load( memory_model::memory_order_relaxed );
+ node_type * pCur = pPrev->next.load( memory_model::memory_order_relaxed );
- if ( pCur == nullptr ) {
+ if ( pCur == pCur->next.load( memory_model::memory_order_relaxed )) {
// end-of-list
- pos.pHead = pHead;
pos.pPrev = pPrev;
- pos.pCur = nullptr;
+ pos.pCur = pCur;
pos.pFound = nullptr;
return false;
}
- value_type * pVal = pos.guard.protect( pCur->data );
+ value_type * pVal = pos.guard.protect( pCur->data,
+ []( marked_data_ptr p ) -> value_type*
+ {
+ return p.ptr();
+ }).ptr();
if ( pVal ) {
- int nCmp = cmp( *pVal, val );
+ int const nCmp = cmp( *pVal, val );
if ( nCmp >= 0 ) {
- pos.pHead = pHead;
pos.pPrev = pPrev;
pos.pCur = pCur;
pos.pFound = pVal;
}
pPrev = pCur;
- pHead = &( pCur->next );
}
}
+
+ template <typename Q, typename Compare >
+ bool inserting_search( node_type const* pHead, Q const& val, insert_position& pos, Compare cmp ) const
+ {
+ pos.pHead = pHead;
+ node_type* pPrev = const_cast<node_type*>(pHead);
+ value_type* pPrevVal = nullptr;
+
+ while ( true ) {
+ node_type * pCur = pPrev->next.load( memory_model::memory_order_relaxed );
+
+ if ( pCur == pCur->next.load( memory_model::memory_order_relaxed ) ) {
+ // end-of-list
+ pos.pPrev = pPrev;
+ pos.pCur = pCur;
+ pos.pFound = nullptr;
+ pos.pPrevVal = pPrevVal;
+ return false;
+ }
+
+ value_type * pVal = pos.guard.protect( pCur->data,
+ []( marked_data_ptr p ) -> value_type*
+ {
+ return p.ptr();
+ } ).ptr();
+
+ if ( pVal ) {
+ int const nCmp = cmp( *pVal, val );
+ if ( nCmp >= 0 ) {
+ pos.pPrev = pPrev;
+ pos.pCur = pCur;
+ pos.pFound = pVal;
+ pos.pPrevVal = pPrevVal;
+ return nCmp == 0;
+ }
+ }
+
+ pPrev = pCur;
+ pPrevVal = pVal;
+ pos.prevGuard.copy( pos.guard );
+ }
+ }
+
//@endcond
private:
//@cond
+ void init_list()
+ {
+ m_Head.next.store( &m_Tail, memory_model::memory_order_relaxed );
+ // end-of-list mark: node.next == node
+ m_Tail.next.store( &m_Tail, memory_model::memory_order_release );
+ }
+
node_type * alloc_node( value_type * pVal )
{
m_Stat.onNodeCreated();
void destroy()
{
- node_type * pNode = m_pHead.load( memory_model::memory_order_relaxed );
- while ( pNode ) {
- value_type * pVal = pNode->data.load( memory_model::memory_order_relaxed );
+ node_type * pNode = m_Head.next.load( memory_model::memory_order_relaxed );
+ while ( pNode != pNode->next.load( memory_model::memory_order_relaxed )) {
+ value_type * pVal = pNode->data.load( memory_model::memory_order_relaxed ).ptr();
if ( pVal )
retire_data( pVal );
node_type * pNext = pNode->next.load( memory_model::memory_order_relaxed );
}
}
- bool link_node( value_type * pVal, position& pos )
+ bool link_data( value_type * pVal, insert_position& pos )
{
- if ( pos.pPrev ) {
- if ( pos.pPrev->data.load( memory_model::memory_order_relaxed ) == nullptr ) {
- // reuse pPrev
- value_type * p = nullptr;
- return pos.pPrev->data.compare_exchange_strong( p, pVal, memory_model::memory_order_release, atomics::memory_order_relaxed );
- }
- else {
- // insert new node between pos.pPrev and pos.pCur
- node_type * pNode = alloc_node( pVal );
- pNode->next.store( pos.pCur, memory_model::memory_order_relaxed );
+ assert( pos.pPrev != nullptr );
+ assert( pos.pCur != nullptr );
- if ( cds_likely( pos.pPrev->next.compare_exchange_strong( pos.pCur, pNode, memory_model::memory_order_release, atomics::memory_order_relaxed )))
- return true;
+ // We need pos.pCur data should be unchanged, otherwise ordering violation can be possible
+ // if current thread will be preempted and another thread will delete pos.pCur data
+ // and then set it to another.
+ // To prevent this we mark pos.pCur data as undeletable by setting LSB
+ marked_data_ptr valCur( pos.pFound );
+ if ( !pos.pCur->data.compare_exchange_strong( valCur, valCur | 1, memory_model::memory_order_acquire, atomics::memory_order_relaxed ) ) {
+ // oops, pos.pCur data has been changed or another thread is setting pos.pPrev data
+ m_Stat.onNodeMarkFailed();
+ return false;
+ }
- delete_node( pNode );
+ marked_data_ptr valPrev( pos.pPrevVal );
+ if ( !pos.pPrev->data.compare_exchange_strong( valPrev, valPrev | 1, memory_model::memory_order_acquire, atomics::memory_order_relaxed ) ) {
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+ m_Stat.onNodeMarkFailed();
+ return false;
+ }
+
+ // checks if link pPrev -> pCur is broken
+ if ( pos.pPrev->next.load( memory_model::memory_order_acquire ) != pos.pCur ) {
+ // sequence pPrev - pCur is broken
+ pos.pPrev->data.store( valPrev, memory_model::memory_order_relaxed );
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+ m_Stat.onNodeSeqBreak();
+ return false;
+ }
+
+ if ( pos.pPrev != pos.pHead && pos.pPrevVal == nullptr )
+ {
+ // reuse pPrev
+
+ // Set pos.pPrev data if it is null
+ valPrev |= 1;
+ bool result = pos.pPrev->data.compare_exchange_strong( valPrev, marked_data_ptr( pVal ),
+ memory_model::memory_order_release, atomics::memory_order_relaxed );
+
+ // Clears data marks
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+
+ if ( result ) {
+ m_Stat.onReuseNode();
+ return result;
}
}
else {
+ // insert new node between pos.pPrev and pos.pCur
node_type * pNode = alloc_node( pVal );
pNode->next.store( pos.pCur, memory_model::memory_order_relaxed );
- if ( cds_likely( pos.pHead->compare_exchange_strong( pos.pCur, pNode, memory_model::memory_order_release, atomics::memory_order_relaxed ) ) )
- return true;
+
+ bool result = pos.pPrev->next.compare_exchange_strong( pos.pCur, pNode, memory_model::memory_order_release, atomics::memory_order_relaxed );
+
+ // Clears data marks
+ pos.pPrev->data.store( valPrev, memory_model::memory_order_relaxed );
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+
+ if ( result ) {
+ m_Stat.onNewNodeCreated();
+ return result;
+ }
delete_node( pNode );
}
+
return false;
}
- static bool unlink_node( position& pos )
+ static bool unlink_data( position& pos )
{
assert( pos.pCur != nullptr );
assert( pos.pFound != nullptr );
- if ( pos.pCur->data.compare_exchange_strong( pos.pFound, nullptr, memory_model::memory_order_acquire, atomics::memory_order_relaxed ) ) {
+ marked_data_ptr val( pos.pFound );
+ if ( pos.pCur->data.compare_exchange_strong( val, marked_data_ptr(), memory_model::memory_order_acquire, atomics::memory_order_relaxed ) ) {
retire_data( pos.pFound );
return true;
}
return false;
}
-
//@endcond
};
}} // namespace cds::intrusive
projects / libcds.git / blobdiff