/*
This file is a part of libcds - Concurrent Data Structures library
- (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
+ (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
Source code repo: http://github.com/khizmax/libcds/
Download: http://sourceforge.net/projects/libcds/files/
-
+
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
/** @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.
Usually, ordered single-linked list is used as a building block for the hash table implementation.
+ Iterable list is suitable for almost append-only hash table because the list doesn't delete
+ its internal node when erasing a key but it is marked them as empty to be reused in the future.
+ However, plenty of empty nodes degrades performance.
+ Separation of internal nodes and user data implies the need for an allocator for internal node
+ so the iterable list is not fully intrusive. Nevertheless, if you need thread-safe iterator,
+ the iterable list is good choice.
+
The complexity of searching is <tt>O(N)</tt>.
Template arguments:
You should select GC you want and include appropriate .h-file:
- for \p gc::HP: <tt> <cds/intrusive/iterable_list_hp.h> </tt>
- for \p gc::DHP: <tt> <cds/intrusive/iterable_list_dhp.h> </tt>
- - for \ref cds_urcu_gc "RCU type" - see \ref cds_intrusive_IterableList_rcu "RCU-based IterableList"
*/
template <
class GC
#endif
>
class IterableList
+#ifndef CDS_DOXYGEN_INVOKED
+ : public iterable_list_tag
+#endif
{
public:
typedef T value_type; ///< type of value stored in the list
typedef typename traits::item_counter item_counter; ///< Item counting policy used
typedef typename traits::memory_model memory_model; ///< Memory ordering. See \p cds::opt::memory_model option
typedef typename traits::node_allocator node_allocator; ///< Node allocator
+ typedef typename traits::stat stat; ///< Internal statistics
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 = 4; ///< Count of hazard pointer required for the algorithm
//@cond
// Rebind traits (split-list support)
, typename cds::opt::make_options< traits, Options...>::type
> type;
};
+
+ // Stat selector
+ template <typename Stat>
+ using select_stat_wrapper = iterable_list::select_stat_wrapper< Stat >;
//@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;
- value_type* m_pVal;
- typename gc::Guard m_Guard; // for m_pVal
+ 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_relaxed );
- if ( !m_pNode )
- break;
- m_pVal = m_Guard.protect( m_pNode->data );
- if ( m_pVal )
- 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_relaxed ))
- , m_pVal( nullptr )
+ explicit iterator_type( node_type const* pNode )
+ : m_pNode( pNode )
{
- if ( m_pNode ) {
- m_pVal = m_Guard.protect( m_pNode->data );
- if ( !m_pVal )
- 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 )
- , m_pVal( pVal )
{
if ( m_pNode ) {
assert( pVal != nullptr );
iterator_type()
: m_pNode( nullptr )
- , m_pVal( nullptr )
{}
iterator_type( iterator_type const& src )
: m_pNode( src.m_pNode )
- , m_pVal( src.m_pVal )
{
- m_Guard.assign( m_pVal );
+ m_Guard.copy( src.m_Guard );
}
value_ptr operator ->() const
{
- return m_pVal;
+ return m_Guard.template get<value_type>();
}
value_ref operator *() const
{
- assert( m_pVal != nullptr );
- return *m_pVal;
+ assert( m_Guard.get_native() != nullptr );
+ return *m_Guard.template get<value_type>();
}
/// Pre-increment
iterator_type& operator = (iterator_type const& src)
{
m_pNode = src.m_pNode;
- m_pVal = src.m_pVal;
- m_Guard.assign( m_pVal );
+ m_Guard.copy( src.m_Guard );
return *this;
}
template <bool C>
bool operator !=(iterator_type<C> const& i ) const
{
- return m_pNode != i.m_pNode;
+ return !( *this == i );
}
};
//@endcond
For some GC (like as \p gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard"
may be thrown if the limit of guard count per thread is exceeded.
- The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
- - Iterator is thread-safe: event if the element the iterator points to is removed, the iterator stays valid because
+ - Iterator is thread-safe: even if the element the iterator points to is removed, the iterator stays valid because
it contains the guard keeping the value from to be recycled.
The iterator interface:
this code
\code
if ( it1 == it2 )
- assert( &(*it1) == &(*it2) );
+ assert( &(*it1) == &(*it2));
\endcode
can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread.
The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing.
*/
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_Stat( st )
+ {
+ init_list();
+ }
+ //@endcond
/// Destroys the list object
~IterableList()
*/
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 );
}
- /// Updates the node
+ /// Insert or update
/**
- The operation performs inserting or changing data with lock-free manner.
+ The operation performs inserting or updating data with lock-free manner.
If the item \p val is not found in the list, then \p val is inserted
iff \p bInsert is \p true.
- Otherwise, the current element is changed to \p val, the element will be retired later
+ Otherwise, the current element is changed to \p val, the old element will be retired later
by call \p Traits::disposer.
Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
\p second is \p true if \p val has been added or \p false if the item with that key
already in the list.
*/
- std::pair<bool, bool> update( value_type& val, bool bInsert = true )
+ std::pair<bool, bool> upsert( value_type& val, bool bInsert = true )
{
- return update_at( m_pHead, val, []( value_type&, value_type* ) {}, bInsert );
+ return upsert_at( &m_Head, val, 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
If \p key is not found the function returns \p end().
*/
template <typename Q>
- iterator find( Q& key ) const
- {
- return find_iterator_at( m_pHead, key, key_comparator());
- }
- //@cond
- 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());
}
- //@endcond
/// 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
If \p key is not found the function returns \p end().
*/
template <typename Q, typename Less>
- iterator find_with( Q& key, Less pred ) const
- {
- CDS_UNUSED( pred );
- return find_iterator_at( m_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
- }
- //@cond
- template <typename Q, typename Less>
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>());
}
- //@endcond
/// 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;
}
}
return m_ItemCounter.value();
}
+ /// Returns const reference to internal statistics
+ stat const& statistics() const
+ {
+ return m_Stat;
+ }
+
protected:
//@cond
-#if 0
+
// 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 );
+ assert( pNode->data.load( memory_model::memory_order_relaxed ) != nullptr );
+
+ insert_position pos;
+
+ while ( true ) {
+ if ( inserting_search( pHead, *pNode->data.load(memory_model::memory_order_relaxed).ptr(), pos, key_comparator())) {
+ m_Stat.onInsertFailed();
+ return false;
+ }
- // 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 ) );
+ if ( link_aux_node( pNode, pos, pHead )) {
+ ++m_ItemCounter;
+ m_Stat.onInsertSuccess();
+ return true;
+ }
+
+ m_Stat.onInsertRetry();
+ }
}
-#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, pHead )) {
++m_ItemCounter;
+ m_Stat.onInsertSuccess();
return true;
}
+
+ m_Stat.onInsertRetry();
}
}
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, pHead )) {
f( val );
++m_ItemCounter;
+ m_Stat.onInsertSuccess();
return true;
}
+
+ m_Stat.onInsertRetry();
}
}
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 );
}
+ m_Stat.onUpdateExisting();
return std::make_pair( true, false );
}
}
else {
- if ( !bInsert )
+ if ( !bInsert ) {
+ m_Stat.onUpdateFailed();
return std::make_pair( false, false );
+ }
- if ( link_node( &val, pos ) ) {
+ if ( link_data( &val, pos, pHead )) {
func( val, static_cast<value_type*>( nullptr ));
++m_ItemCounter;
+ m_Stat.onUpdateNew();
return std::make_pair( true, true );
}
}
+
+ m_Stat.onUpdateRetry();
}
}
- bool unlink_at( atomic_node_ptr& refHead, value_type& val )
+ std::pair<bool, bool> upsert_at( node_type* pHead, value_type& val, bool bInsert )
+ {
+ return update_at( pHead, val, []( value_type&, value_type* ) {}, bInsert );
+ }
+
+ 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;
}
else
}
else
break;
+
+ m_Stat.onEraseRetry();
}
+
+ m_Stat.onEraseFailed();
return false;
}
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();
return true;
}
else
bkoff();
+
+ m_Stat.onEraseRetry();
}
+
+ m_Stat.onEraseFailed();
return false;
}
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;
- return true;
+ m_Stat.onEraseSuccess();
+ assert( pos.pFound != nullptr );
+ return guarded_ptr( std::move( pos.guard ));
}
else
bkoff();
+
+ m_Stat.onEraseRetry();
}
- return false;
+
+ m_Stat.onEraseFailed();
+ 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;
- return search( refHead, val, pos, cmp );
+ if ( search( pHead, val, pos, cmp )) {
+ m_Stat.onFindSuccess();
+ return true;
+ }
+
+ m_Stat.onFindFailed();
+ return false;
}
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();
return true;
}
+
+ m_Stat.onFindFailed();
return false;
}
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();
return iterator( pos.pCur, pos.pFound );
}
- return iterator{};
+
+ m_Stat.onFindFailed();
+ 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 );
- return true;
+ if ( search( pHead, val, pos, cmp )) {
+ m_Stat.onFindSuccess();
+ return guarded_ptr( std::move( pos.guard ));
}
- return false;
+
+ m_Stat.onFindFailed();
+ 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_acquire )) {
// 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 = pPrev->data.load( memory_model::memory_order_relaxed ).ptr();
+
+ while ( true ) {
+ node_type * pCur = pPrev->next.load( memory_model::memory_order_relaxed );
+
+ if ( pCur == pCur->next.load( memory_model::memory_order_acquire )) {
+ // 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 );
+ }
+ }
+
+ // split-list support
+ template <typename Predicate>
+ void destroy( Predicate pred )
+ {
+ 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();
+ node_type * pNext = pNode->next.load( memory_model::memory_order_relaxed );
+ bool const is_regular_node = !pVal || pred( pVal );
+ if ( is_regular_node ) {
+ if ( pVal )
+ retire_data( pVal );
+ delete_node( pNode );
+ }
+ pNode = pNext;
+ }
+
+ m_Head.next.store( &m_Tail, memory_model::memory_order_relaxed );
+ }
//@endcond
private:
//@cond
- static node_type * alloc_node( value_type * pVal )
+ 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();
return cxx_node_allocator().New( pVal );
}
- static void delete_node( node_type * pNode )
+ void delete_node( node_type * pNode )
{
+ m_Stat.onNodeRemoved();
cxx_node_allocator().Delete( pNode );
}
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 );
}
}
- static bool link_node( value_type * pVal, position& pos )
+ bool link_data( value_type* pVal, insert_position& pos, node_type* pHead )
{
- 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 );
+ assert( pos.pPrev != nullptr );
+ assert( pos.pCur != nullptr );
+
+ // 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;
+ }
+
+ 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.pPrevVal == nullptr ) {
+ // Check ABA-problem for prev
+ // There is a possibility that the current thread was preempted
+ // on entry of this function. Other threads can link data to prev
+ // and then remove it. As a result, the order of items may be changed
+ if ( find_prev( pHead, *pVal ) != pos.pPrev ) {
+ pos.pPrev->data.store( valPrev, memory_model::memory_order_relaxed );
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+
+ m_Stat.onNullPrevABA();
+ return false;
}
- 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.pPrev->next.compare_exchange_strong( pos.pCur, pNode, memory_model::memory_order_release, atomics::memory_order_relaxed )))
- return true;
+ if ( pos.pPrev != pos.pHead && pos.pPrevVal == nullptr ) {
+ // reuse pPrev
- delete_node( pNode );
+ // 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 )
+ // split-list support
+ bool link_aux_node( node_type * pNode, insert_position& pos, node_type* pHead )
+ {
+ assert( pos.pPrev != nullptr );
+ assert( pos.pCur != nullptr );
+
+ // 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;
+ }
+
+ 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.pPrevVal == nullptr ) {
+ // Check ABA-problem for prev
+ // There is a possibility that the current thread was preempted
+ // on entry of this function. Other threads can insert (link) an item to prev
+ // and then remove it. As a result, the order of items may be changed
+ if ( find_prev( pHead, *pNode->data.load( memory_model::memory_order_relaxed ).ptr()) != pos.pPrev ) {
+ pos.pPrev->data.store( valPrev, memory_model::memory_order_relaxed );
+ pos.pCur->data.store( valCur, memory_model::memory_order_relaxed );
+
+ m_Stat.onNullPrevABA();
+ return false;
+ }
+ }
+
+ // insert new node between pos.pPrev and pos.pCur
+ pNode->next.store( pos.pCur, memory_model::memory_order_relaxed );
+
+ 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 );
+
+ return result;
+ }
+
+ 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;
}
+ template <typename Q>
+ node_type* find_prev( node_type const* pHead, Q const& val ) const
+ {
+ node_type* pPrev = const_cast<node_type*>(pHead);
+ typename gc::Guard guard;
+ key_comparator cmp;
+
+ while ( true ) {
+ node_type * pCur = pPrev->next.load( memory_model::memory_order_relaxed );
+
+ if ( pCur == pCur->next.load( memory_model::memory_order_acquire )) {
+ // end-of-list
+ return pPrev;
+ }
+
+ value_type * pVal = guard.protect( pCur->data,
+ []( marked_data_ptr p ) -> value_type*
+ {
+ return p.ptr();
+ } ).ptr();
+
+ if ( pVal && cmp( *pVal, val ) >= 0 )
+ return pPrev;
+
+ pPrev = pCur;
+ }
+ }
//@endcond
};
}} // namespace cds::intrusive
projects / libcds.git / blobdiff