-//$$CDS-header$$
-
-#ifndef __CDS_INTRUSIVE_SEGMENTED_QUEUE_H
-#define __CDS_INTRUSIVE_SEGMENTED_QUEUE_H
+/*
+ This file is a part of libcds - Concurrent Data Structures library
+
+ (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
+
+ Source code repo: http://github.com/khizmax/libcds/
+ Download: http://sourceforge.net/projects/libcds/files/
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef CDSLIB_INTRUSIVE_SEGMENTED_QUEUE_H
+#define CDSLIB_INTRUSIVE_SEGMENTED_QUEUE_H
#include <mutex>
#include <cds/intrusive/details/base.h>
#include <cds/details/marked_ptr.h>
#include <cds/algo/int_algo.h>
-#include <cds/lock/spinlock.h>
+#include <cds/sync/spinlock.h>
#include <cds/opt/permutation.h>
#include <boost/intrusive/slist.hpp>
/// Alignment of critical data, default is cache line alignment. See cds::opt::alignment option specification
enum { alignment = opt::cache_line_alignment };
+ /// Padding of segment data, default is no special padding
+ /**
+ The segment is just an array of atomic data pointers,
+ so, the high load leads to false sharing and performance degradation.
+ A padding of segment data can eliminate false sharing issue.
+ On the other hand, the padding leads to increase segment size.
+ */
+ enum { padding = opt::no_special_padding };
+
/// Segment allocator. Default is \ref CDS_DEFAULT_ALLOCATOR
typedef CDS_DEFAULT_ALLOCATOR allocator;
/// Lock type used to maintain an internal list of allocated segments
- typedef cds::lock::Spin lock_type;
+ typedef cds::sync::spin lock_type;
/// Random \ref cds::opt::permutation_generator "permutation generator" for sequence [0, quasi_factor)
typedef cds::opt::v::random2_permutation<int> permutation_generator;
all other \p %segmented_queue::traits members left unchanged.
\p Options are:
- - \p opt::disposer - the functor used for dispose removed items.
+ - \p opt::disposer - the functor used to dispose removed items.
- \p opt::stat - internal statistics, possible type: \p segmented_queue::stat, \p segmented_queue::empty_stat (the default)
- \p opt::item_counter - item counting feature. Note that \p atomicity::empty_item_counetr is not suitable
for segmented queue.
- \p opt::memory_model - memory model, default is \p opt::v::relaxed_ordering.
See option description for the full list of possible models
- \p opt::alignment - the alignment for critical data, see option description for explanation
+ - \p opt::padding - the padding of segment data, default no special padding.
+ See \p traits::padding for explanation.
- \p opt::allocator - the allocator to be used for maintaining segments.
- \p opt::lock_type - a mutual exclusion lock type used to maintain internal list of allocated
segments. Default is \p cds::opt::Spin, \p std::mutex is also suitable.
quasi factor. This means that the consumer dequeues <i>any</i> item from the current first segment.
Template parameters:
- - \p GC - a garbage collector, possible types are cds::gc::HP, cds::gc::PTB
+ - \p GC - a garbage collector, possible types are cds::gc::HP, cds::gc::DHP
- \p T - the type of values stored in the queue
- \p Traits - queue type traits, default is \p segmented_queue::traits.
\p segmented_queue::make_traits metafunction can be used to construct the
typedef typename traits::lock_type lock_type; ///< Type of mutex for maintaining an internal list of allocated segments.
typedef typename traits::permutation_generator permutation_generator; ///< Random permutation generator for sequence [0, quasi-factor)
- static const size_t m_nHazardPtrCount = 2 ; ///< Count of hazard pointer required for the algorithm
+ static const size_t c_nHazardPtrCount = 2 ; ///< Count of hazard pointer required for the algorithm
protected:
//@cond
// Segment cell. LSB is used as deleted mark
- typedef cds::details::marked_ptr< value_type, 1 > cell;
+ typedef cds::details::marked_ptr< value_type, 1 > regular_cell;
+ typedef atomics::atomic< regular_cell > atomic_cell;
+ typedef typename cds::opt::details::apply_padding< atomic_cell, traits::padding >::type cell;
// Segment
struct segment: public boost::intrusive::slist_base_hook<>
{
- atomics::atomic< cell > * cells; // Cell array of size \ref m_nQuasiFactor
- size_t version; // version tag (ABA prevention tag)
+ cell * cells; // Cell array of size \ref m_nQuasiFactor
+ size_t version; // version tag (ABA prevention tag)
// cell array is placed here in one continuous memory block
// Initializes the segment
segment( size_t nCellCount )
// MSVC warning C4355: 'this': used in base member initializer list
- : cells( reinterpret_cast< atomics::atomic< cell > * >( this + 1 ))
+ : cells( reinterpret_cast< cell *>( this + 1 ))
, version( 0 )
{
init( nCellCount );
}
+ segment() = delete;
+
void init( size_t nCellCount )
{
- atomics::atomic< cell > * pLastCell = cells + nCellCount;
- for ( atomics::atomic< cell > * pCell = cells; pCell < pLastCell; ++pCell )
- pCell->store( cell(), atomics::memory_order_relaxed );
+ cell * pLastCell = cells + nCellCount;
+ for ( cell* pCell = cells; pCell < pLastCell; ++pCell )
+ pCell->data.store( regular_cell(), atomics::memory_order_relaxed );
atomics::atomic_thread_fence( memory_model::memory_order_release );
}
-
- private:
- segment(); //=delete
};
typedef typename opt::details::alignment_setter< atomics::atomic<segment *>, traits::alignment >::type aligned_segment_ptr;
bool populated( segment const& s ) const
{
// The lock should be held
- atomics::atomic< cell > const * pLastCell = s.cells + quasi_factor();
- for ( atomics::atomic< cell > const * pCell = s.cells; pCell < pLastCell; ++pCell ) {
- if ( !pCell->load( memory_model::memory_order_relaxed ).all() )
+ cell const * pLastCell = s.cells + quasi_factor();
+ for ( cell const * pCell = s.cells; pCell < pLastCell; ++pCell ) {
+ if ( !pCell->data.load( memory_model::memory_order_relaxed ).all() )
return false;
}
return true;
bool exhausted( segment const& s ) const
{
// The lock should be held
- atomics::atomic< cell > const * pLastCell = s.cells + quasi_factor();
- for ( atomics::atomic< cell > const * pCell = s.cells; pCell < pLastCell; ++pCell ) {
- if ( !pCell->load( memory_model::memory_order_relaxed ).bits() )
+ cell const * pLastCell = s.cells + quasi_factor();
+ for ( cell const * pCell = s.cells; pCell < pLastCell; ++pCell ) {
+ if ( !pCell->data.load( memory_model::memory_order_relaxed ).bits() )
return false;
}
return true;
return guard.assign( &m_List.back() );
}
+# ifdef _DEBUG
assert( m_List.empty() || populated( m_List.back() ));
+# endif
segment * pNew = allocate_segment();
m_Stat.onSegmentCreated();
if ( m_List.empty() )
- m_pHead.store( pNew, memory_model::memory_order_relaxed );
+ m_pHead.store( pNew, memory_model::memory_order_release );
m_List.push_back( *pNew );
m_pTail.store( pNew, memory_model::memory_order_release );
return guard.assign( pNew );
return guard.assign( &m_List.front() );
}
- assert( exhausted(m_List.front()) );
+# ifdef _DEBUG
+ assert( exhausted( m_List.front()));
+# endif
m_List.pop_front();
if ( m_List.empty() ) {
segment * allocate_segment()
{
- return segment_allocator().NewBlock( sizeof(segment) + sizeof(cell) * m_nQuasiFactor,
- quasi_factor() );
+ return segment_allocator().NewBlock( sizeof(segment) + sizeof(cell) * m_nQuasiFactor, quasi_factor() );
}
static void free_segment( segment * pSegment )
do {
typename permutation_generator::integer_type i = gen;
CDS_DEBUG_ONLY( ++nLoopCount );
- if ( pTailSegment->cells[i].load(memory_model::memory_order_relaxed).all() ) {
+ if ( pTailSegment->cells[i].data.load(memory_model::memory_order_relaxed).all() ) {
// Cell is not empty, go next
m_Stat.onPushPopulated();
}
else {
// Empty cell found, try to enqueue here
- cell nullCell;
- if ( pTailSegment->cells[i].compare_exchange_strong( nullCell, cell( &val ),
+ regular_cell nullCell;
+ if ( pTailSegment->cells[i].data.compare_exchange_strong( nullCell, regular_cell( &val ),
memory_model::memory_order_release, atomics::memory_order_relaxed ))
{
// Ok to push item
/// Clear the queue
/**
- The function repeatedly calls \ref dequeue until it returns \p nullptr.
+ The function repeatedly calls \p dequeue() until it returns \p nullptr.
The disposer specified in \p Traits template argument is called for each removed item.
*/
void clear()
}
bool bHadNullValue = false;
- cell item;
+ regular_cell item;
CDS_DEBUG_ONLY( size_t nLoopCount = 0 );
do {
typename permutation_generator::integer_type i = gen;
// Guard the item
// In segmented queue the cell cannot be reused
// So no loop is needed here to protect the cell
- item = pHeadSegment->cells[i].load( memory_model::memory_order_relaxed );
+ item = pHeadSegment->cells[i].data.load( memory_model::memory_order_relaxed );
itemGuard.assign( item.ptr() );
// Check if this cell is empty, which means an element
// If the item is not deleted yet
if ( !item.bits() ) {
// Try to mark the cell as deleted
- if ( pHeadSegment->cells[i].compare_exchange_strong( item, item | 1,
+ if ( pHeadSegment->cells[i].data.compare_exchange_strong( item, item | 1,
memory_model::memory_order_acquire, atomics::memory_order_relaxed ))
{
--m_ItemCounter;
# pragma warning( pop )
#endif
-#endif // #ifndef __CDS_INTRUSIVE_SEGMENTED_QUEUE_H
+#endif // #ifndef CDSLIB_INTRUSIVE_SEGMENTED_QUEUE_H
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