SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CDSLIB_INTRUSIVE_IMPL_MICHAEL_LIST_H
# endif
typedef typename traits::disposer disposer; ///< disposer used
+ typedef typename traits::stat stat; ///< Internal statistics
typedef typename get_node_traits< value_type, node_type, hook>::type node_traits ; ///< node traits
typedef typename michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker; ///< link checker
typedef typename gc::template guarded_ptr< value_type > guarded_ptr; ///< Guarded pointer
+ static CDS_CONSTEXPR const size_t c_nHazardPtrCount = 4; ///< Count of hazard pointer required for the algorithm
+
//@cond
// Rebind traits (split-list support)
template <typename... Options>
, typename cds::opt::make_options< traits, Options...>::type
> type;
};
+
+ // Stat selector
+ template <typename Stat>
+ using select_stat_wrapper = michael_list::select_stat_wrapper< Stat >;
//@endcond
protected:
typedef atomic_node_ptr auxiliary_head; ///< Auxiliary head type (for split-list support)
- atomic_node_ptr m_pHead; ///< Head pointer
- item_counter m_ItemCounter; ///< Item counter
+ atomic_node_ptr m_pHead; ///< Head pointer
+ item_counter m_ItemCounter; ///< Item counter
+ stat m_Stat; ///< Internal statistics
//@cond
/// Position pointer for item search
marked_node_ptr cur(pos.pCur);
pNode->m_pNext.store( cur, memory_model::memory_order_release );
- return pos.pPrev->compare_exchange_strong( cur, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed );
+ if ( cds_likely( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr(pNode), memory_model::memory_order_release, atomics::memory_order_relaxed )))
+ return true;
+
+ pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
+ return false;
}
static bool unlink_node( position& pos )
// Mark the node (logical deleting)
marked_node_ptr next(pos.pNext, 0);
- if ( pos.pCur->m_pNext.compare_exchange_strong( next, marked_node_ptr(pos.pNext, 1), memory_model::memory_order_release, atomics::memory_order_relaxed )) {
+ if ( cds_likely( pos.pCur->m_pNext.compare_exchange_strong( next, marked_node_ptr(pos.pNext, 1), memory_model::memory_order_release, atomics::memory_order_relaxed ))) {
// physical deletion may be performed by search function if it detects that a node is logically deleted (marked)
// CAS may be successful here or in other thread that searching something
marked_node_ptr cur(pos.pCur);
- if ( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr( pos.pNext ), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))
+ if ( cds_likely( pos.pPrev->compare_exchange_strong( cur, marked_node_ptr( pos.pNext ), memory_model::memory_order_acquire, atomics::memory_order_relaxed )))
retire_node( pos.pCur );
return true;
}
do {
pNext = pCur->m_pNext.load(memory_model::memory_order_relaxed);
g.assign( node_traits::to_value_ptr( pNext.ptr()));
- } while ( pNext != pCur->m_pNext.load(memory_model::memory_order_acquire));
+ } while ( cds_unlikely( pNext != pCur->m_pNext.load(memory_model::memory_order_acquire)));
if ( pNext.ptr())
m_pNode = m_Guard.assign( g.template get<value_type>());
m_pNode = nullptr;
m_Guard.clear();
}
- if ( p == pNode.load(memory_model::memory_order_acquire))
+ if ( cds_likely( p == pNode.load(memory_model::memory_order_acquire)))
break;
}
}
//@endcond
public:
+ ///@name Forward iterators (only for debugging purpose)
+ //@{
/// Forward iterator
/**
The forward iterator for Michael's list has some features:
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 ensures thread-safety even if you delete the item the iterator points to. However, in case of concurrent
- deleting operations there is no guarantee that you iterate all item in the list.
+ deleting operations there is no guarantee that you iterate all item in the list.
+ Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread.
- Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
- for debug purpose only.
+ @warning Use this iterator on the concurrent container for debugging purpose only.
The iterator interface:
\code
{
return const_iterator();
}
+ //@}
public:
/// Default constructor initializes empty list
static_assert( (std::is_same< gc, typename node_type::gc >::value), "GC and node_type::gc must be the same type" );
}
+ //@cond
+ template <typename Stat, typename = std::enable_if<std::is_same<stat, michael_list::wrapped_stat<Stat>>::value >>
+ explicit MichaelList( Stat& st )
+ : m_pHead( nullptr )
+ , m_Stat( st )
+ {}
+ //@endcond
+
/// Destroys the list object
~MichaelList()
{
The functor may 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.
- Returns std::pair<bool, bool> 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 list.
+ Returns std::pair<bool, bool> where \p first is \p true if operation is successful,
+ \p second is \p true if new item has been added or \p false if the item with that key
+ already in the list.
@warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
*/
only if \p val is an item of the list, i.e. the pointer to item found
is equal to <tt> &val </tt>.
+ \p disposer specified in \p Traits is called for deleted item.
+
The function returns \p true if success and \p false otherwise.
*/
bool unlink( value_type& val )
The function searches an item with key equal to \p key in the list,
unlinks it from the list, and returns \p true.
If \p key is not found the function return \p false.
+
+ \p disposer specified in \p Traits is called for deleted item.
*/
template <typename Q>
bool erase( Q const& key )
but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the list.
+
+ \p disposer specified in \p Traits is called for deleted item.
*/
template <typename Q, typename Less>
bool erase_with( Q const& key, Less pred )
};
\endcode
If \p key is not found the function return \p false, \p func is not called.
+
+ \p disposer specified in \p Traits is called for deleted item.
*/
template <typename Q, typename Func>
bool erase( Q const& key, Func func )
but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the list.
+
+ \p disposer specified in \p Traits is called for deleted item.
*/
template <typename Q, typename Less, typename Func>
bool erase_with( Q const& key, Less pred, Func f )
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_pHead, 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_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Finds \p key in the list
template <typename Q>
guarded_ptr get( Q const& key )
{
- guarded_ptr gp;
- get_at( m_pHead, gp.guard(), key, key_comparator());
- return gp;
+ return get_at( m_pHead, key, key_comparator());
}
/// Finds the \p key and return the item found
guarded_ptr get_with( Q const& key, Less pred )
{
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_pHead, key, cds::opt::details::make_comparator_from_less<Less>());
}
/// Clears the list
head = m_pHead.load(memory_model::memory_order_relaxed);
if ( head.ptr())
guard.assign( node_traits::to_value_ptr( *head.ptr()));
- if ( m_pHead.load(memory_model::memory_order_acquire) == head ) {
+ if ( cds_likely( m_pHead.load(memory_model::memory_order_acquire) == head )) {
if ( head.ptr() == nullptr )
break;
value_type& val = *node_traits::to_value_ptr( *head.ptr());
this function always returns 0.
@note Even if you use real item counter and it returns 0, this fact does not mean that the list
- is empty. To check list emptyness use \p empty() method.
+ is empty. To check list emptiness use \p empty() method.
*/
size_t size() const
{
return m_ItemCounter.value();
}
+ /// Returns const reference to internal statistics
+ stat const& statistics() const
+ {
+ return m_Stat;
+ }
+
protected:
//@cond
// split-list support
bool insert_at( atomic_node_ptr& refHead, value_type& val )
{
node_type * pNode = node_traits::to_node_ptr( val );
- link_checker::is_empty( pNode );
position pos;
while ( true ) {
- if ( search( refHead, val, pos, key_comparator()))
+ if ( search( refHead, val, pos, key_comparator())) {
+ m_Stat.onInsertFailed();
return false;
+ }
if ( link_node( pNode, pos )) {
++m_ItemCounter;
+ m_Stat.onInsertSuccess();
return true;
}
- // clear next field
- pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
+ m_Stat.onInsertRetry();
}
}
bool insert_at( atomic_node_ptr& refHead, value_type& val, Func f )
{
node_type * pNode = node_traits::to_node_ptr( val );
- link_checker::is_empty( pNode );
position pos;
while ( true ) {
- if ( search( refHead, val, pos, key_comparator()))
+ if ( search( refHead, val, pos, key_comparator())) {
+ m_Stat.onInsertFailed();
return false;
+ }
typename gc::Guard guard;
guard.assign( &val );
if ( link_node( pNode, pos )) {
f( val );
++m_ItemCounter;
+ m_Stat.onInsertSuccess();
return true;
}
- // clear next field
- pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
+ m_Stat.onInsertRetry();
}
}
node_type * pNode = node_traits::to_node_ptr( val );
while ( true ) {
if ( search( refHead, val, pos, key_comparator())) {
- if ( pos.pCur->m_pNext.load(memory_model::memory_order_acquire).bits()) {
+ if ( cds_unlikely( pos.pCur->m_pNext.load(memory_model::memory_order_acquire).bits())) {
back_off()();
+ m_Stat.onUpdateMarked();
continue; // the node found is marked as deleted
}
assert( key_comparator()( val, *node_traits::to_value_ptr( *pos.pCur )) == 0 );
func( false, *node_traits::to_value_ptr( *pos.pCur ) , val );
+ m_Stat.onUpdateExisting();
return std::make_pair( true, false );
}
else {
- if ( !bInsert )
+ if ( !bInsert ) {
+ m_Stat.onUpdateFailed();
return std::make_pair( false, false );
+ }
typename gc::Guard guard;
guard.assign( &val );
if ( link_node( pNode, pos )) {
++m_ItemCounter;
func( true, val, val );
+ m_Stat.onUpdateNew();
return std::make_pair( true, true );
}
- // clear next field
- pNode->m_pNext.store( marked_node_ptr(), memory_model::memory_order_relaxed );
}
+
+ m_Stat.onUpdateRetry();
}
}
if ( node_traits::to_value_ptr( *pos.pCur ) == &val ) {
if ( unlink_node( pos )) {
--m_ItemCounter;
+ m_Stat.onEraseSuccess();
return true;
}
else
bkoff();
}
- else
+ else {
+ m_Stat.onUpdateFailed();
break;
+ }
+
+ m_Stat.onEraseRetry();
}
+
+ m_Stat.onEraseFailed();
return false;
}
if ( unlink_node( pos )) {
f( *node_traits::to_value_ptr( *pos.pCur ));
--m_ItemCounter;
+ m_Stat.onEraseSuccess();
return true;
}
else
bkoff();
+
+ m_Stat.onEraseRetry();
}
+
+ m_Stat.onEraseFailed();
return false;
}
}
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( atomic_node_ptr& refHead, Q const& val, Compare cmp )
{
position pos;
back_off bkoff;
while ( search( refHead, val, pos, cmp )) {
if ( unlink_node( pos )) {
- dest.set( pos.guards.template get<value_type>( position::guard_current_item ));
--m_ItemCounter;
- return true;
+ m_Stat.onEraseSuccess();
+ return guarded_ptr( pos.guards.release( position::guard_current_item ));
}
else
bkoff();
+ m_Stat.onEraseRetry();
}
- return false;
+
+ m_Stat.onEraseFailed();
+ return guarded_ptr();
}
template <typename Q, typename Compare>
bool find_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
{
position pos;
- return search( refHead, val, pos, cmp );
+ if ( search( refHead, val, pos, cmp ) ) {
+ m_Stat.onFindSuccess();
+ return true;
+ }
+
+ m_Stat.onFindFailed();
+ return false;
}
template <typename Q, typename Compare, typename Func>
position pos;
if ( search( refHead, val, pos, cmp )) {
f( *node_traits::to_value_ptr( *pos.pCur ), val );
+ m_Stat.onFindSuccess();
return true;
}
+
+ m_Stat.onFindFailed();
return false;
}
template <typename Q, typename Compare>
- bool get_at( atomic_node_ptr& refHead, typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp )
+ guarded_ptr get_at( atomic_node_ptr& refHead, Q const& val, Compare cmp )
{
position pos;
if ( search( refHead, val, pos, cmp )) {
- guard.set( pos.guards.template get<value_type>( position::guard_current_item ));
- return true;
+ m_Stat.onFindSuccess();
+ return guarded_ptr( pos.guards.release( position::guard_current_item ));
}
- return false;
+
+ m_Stat.onFindFailed();
+ return guarded_ptr();
}
//@endcond
{
return node_traits::to_value_ptr( p.ptr());
});
- if ( pPrev->load(memory_model::memory_order_acquire).all() != pCur.ptr()) {
+ if ( cds_unlikely( pPrev->load(memory_model::memory_order_acquire).all() != pCur.ptr())) {
bkoff();
goto try_again;
}
if ( pNext.bits() == 1 ) {
// pCur marked i.e. logically deleted. Help the erase/unlink function to unlink pCur node
marked_node_ptr cur( pCur.ptr());
- if ( pPrev->compare_exchange_strong( cur, marked_node_ptr( pNext.ptr()), memory_model::memory_order_acquire, atomics::memory_order_relaxed )) {
+ if ( cds_unlikely( pPrev->compare_exchange_strong( cur, marked_node_ptr( pNext.ptr()), memory_model::memory_order_acquire, atomics::memory_order_relaxed ))) {
retire_node( pCur.ptr());
+ m_Stat.onHelpingSuccess();
}
else {
bkoff();
+ m_Stat.onHelpingFailed();
goto try_again;
}
}
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