--- /dev/null
+/*
+ This file is a part of libcds - Concurrent Data Structures library
+
+ (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:
+
+ * 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_CONTAINER_SEGMENTED_QUEUE_H
+#define CDSLIB_CONTAINER_SEGMENTED_QUEUE_H
+
+#include <memory>
+#include <functional> // ref
+#include <cds/intrusive/segmented_queue.h>
+#include <cds/details/trivial_assign.h>
+
+namespace cds { namespace container {
+
+ /// SegmentedQueue -related declarations
+ namespace segmented_queue {
+
+# ifdef CDS_DOXYGEN_INVOKED
+ /// SegmentedQueue internal statistics
+ typedef cds::intrusive::segmented_queue::stat stat;
+# else
+ using cds::intrusive::segmented_queue::stat;
+# endif
+
+ /// SegmentedQueue empty internal statistics (no overhead)
+ typedef cds::intrusive::segmented_queue::empty_stat empty_stat;
+
+ /// SegmentedQueue default type traits
+ struct traits {
+
+ /// Item allocator. Default is \ref CDS_DEFAULT_ALLOCATOR
+ typedef CDS_DEFAULT_ALLOCATOR node_allocator;
+
+ /// Item counter, default is atomicity::item_counter
+ /**
+ The item counting is an essential part of segmented queue algorithm.
+ The \p empty() member function is based on checking <tt>size() == 0</tt>.
+ Therefore, dummy item counter like atomicity::empty_item_counter is not the proper counter.
+ */
+ typedef atomicity::item_counter item_counter;
+
+ /// Internal statistics, possible predefined types are \ref stat, \ref empty_stat (the default)
+ typedef segmented_queue::empty_stat stat;
+
+ /// Memory model, default is opt::v::relaxed_ordering. See cds::opt::memory_model for the full list of possible types
+ typedef opt::v::relaxed_ordering memory_model;
+
+ /// 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 = cds::intrusive::segmented_queue::traits::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::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;
+ };
+
+ /// Metafunction converting option list to traits for SegmentedQueue
+ /**
+ The metafunction can be useful if a few fields in \p segmented_queue::traits should be changed.
+ For example:
+ \code
+ typedef cds::container::segmented_queue::make_traits<
+ cds::opt::item_counter< cds::atomicity::item_counter >
+ >::type my_segmented_queue_traits;
+ \endcode
+ This code creates \p %SegmentedQueue type traits with item counting feature,
+ all other \p segmented_queue::traits members left unchanged.
+
+ \p Options are:
+ - \p opt::node_allocator - node allocator.
+ - \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 of 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 used to maintain 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.
+ - \p opt::permutation_generator - a random permutation generator for sequence [0, quasi_factor),
+ default is \p cds::opt::v::random2_permutation<int>
+ */
+ template <typename... Options>
+ struct make_traits {
+# ifdef CDS_DOXYGEN_INVOKED
+ typedef implementation_defined type ; ///< Metafunction result
+# else
+ typedef typename cds::opt::make_options<
+ typename cds::opt::find_type_traits< traits, Options... >::type
+ ,Options...
+ >::type type;
+# endif
+ };
+
+ } // namespace segmented_queue
+
+ //@cond
+ namespace details {
+
+ template <typename GC, typename T, typename Traits>
+ struct make_segmented_queue
+ {
+ typedef GC gc;
+ typedef T value_type;
+ typedef Traits original_type_traits;
+
+ typedef cds::details::Allocator< T, typename original_type_traits::node_allocator > cxx_node_allocator;
+ struct node_disposer {
+ void operator()( T * p )
+ {
+ cxx_node_allocator().Delete( p );
+ }
+ };
+
+ struct intrusive_type_traits: public original_type_traits
+ {
+ typedef node_disposer disposer;
+ };
+
+ typedef cds::intrusive::SegmentedQueue< gc, value_type, intrusive_type_traits > type;
+ };
+
+ } // namespace details
+ //@endcond
+
+ /// Segmented queue
+ /** @ingroup cds_nonintrusive_queue
+
+ The queue is based on work
+ - [2010] Afek, Korland, Yanovsky "Quasi-Linearizability: relaxed consistency for improved concurrency"
+
+ In this paper the authors offer a relaxed version of linearizability, so-called quasi-linearizability,
+ that preserves some of the intuition, provides a flexible way to control the level of relaxation
+ and supports th implementation of more concurrent and scalable data structure.
+ Intuitively, the linearizability requires each run to be equivalent in some sense to a serial run
+ of the algorithm. This equivalence to some serial run imposes strong synchronization requirements
+ that in many cases results in limited scalability and synchronization bottleneck.
+
+ The general idea is that the queue maintains a linked list of segments, each segment is an array of
+ nodes in the size of the quasi factor, and each node has a deleted boolean marker, which states
+ if it has been dequeued. Each producer iterates over last segment in the linked list in some random
+ permutation order. Whet it finds an empty cell it performs a CAS operation attempting to enqueue its
+ new element. In case the entire segment has been scanned and no available cell is found (implying
+ that the segment is full), then it attempts to add a new segment to the list.
+
+ The dequeue operation is similar: the consumer iterates over the first segment in the linked list
+ in some random permutation order. When it finds an item which has not yet been dequeued, it performs
+ CAS on its deleted marker in order to "delete" it, if succeeded this item is considered dequeued.
+ In case the entire segment was scanned and all the nodes have already been dequeued (implying that
+ the segment is empty), then it attempts to remove this segment from the linked list and starts
+ the same process on the next segment. If there is no next segment, the queue is considered empty.
+
+ Based on the fact that most of the time threads do not add or remove segments, most of the work
+ is done in parallel on different cells in the segments. This ensures a controlled contention
+ depending on the segment size, which is quasi factor.
+
+ The segmented queue is an <i>unfair</i> queue since it violates the strong FIFO order but no more than
+ quasi factor. It means that the consumer dequeues any item from the current first segment.
+
+ Template parameters:
+ - \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 your
+ type traits.
+ */
+ template <class GC, typename T, typename Traits = segmented_queue::traits >
+ class SegmentedQueue:
+#ifdef CDS_DOXYGEN_INVOKED
+ public cds::intrusive::SegmentedQueue< GC, T, Traits >
+#else
+ public details::make_segmented_queue< GC, T, Traits >::type
+#endif
+ {
+ //@cond
+ typedef details::make_segmented_queue< GC, T, Traits > maker;
+ typedef typename maker::type base_class;
+ //@endcond
+ public:
+ typedef GC gc; ///< Garbage collector
+ typedef T value_type; ///< type of the value stored in the queue
+ typedef Traits traits; ///< Queue traits
+
+ typedef typename traits::node_allocator node_allocator; ///< Node allocator
+ typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
+ typedef typename base_class::item_counter item_counter; ///< Item counting policy, see cds::opt::item_counter option setter
+ typedef typename base_class::stat stat ; ///< Internal statistics policy
+ typedef typename base_class::lock_type lock_type ; ///< Type of mutex for maintaining an internal list of allocated segments.
+ typedef typename base_class::permutation_generator permutation_generator; ///< Random permutation generator for sequence [0, quasi-factor)
+
+ static const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount ; ///< Count of hazard pointer required for the algorithm
+
+ protected:
+ //@cond
+ typedef typename maker::cxx_node_allocator cxx_node_allocator;
+ typedef std::unique_ptr< value_type, typename maker::node_disposer > scoped_node_ptr;
+
+ static value_type * alloc_node( value_type const& v )
+ {
+ return cxx_node_allocator().New( v );
+ }
+
+ static value_type * alloc_node()
+ {
+ return cxx_node_allocator().New();
+ }
+
+ template <typename... Args>
+ static value_type * alloc_node_move( Args&&... args )
+ {
+ return cxx_node_allocator().MoveNew( std::forward<Args>( args )... );
+ }
+ //@endcond
+
+ public:
+ /// Initializes the empty queue
+ SegmentedQueue(
+ size_t nQuasiFactor ///< Quasi factor. If it is not a power of 2 it is rounded up to nearest power of 2. Minimum is 2.
+ )
+ : base_class( nQuasiFactor )
+ {}
+
+ /// Clears the queue and deletes all internal data
+ ~SegmentedQueue()
+ {}
+
+ /// Inserts a new element at last segment of the queue
+ /**
+ The function makes queue node in dynamic memory calling copy constructor for \p val
+ and then it calls intrusive::SEgmentedQueue::enqueue.
+ Returns \p true if success, \p false otherwise.
+ */
+ bool enqueue( value_type const& val )
+ {
+ scoped_node_ptr p( alloc_node(val));
+ if ( base_class::enqueue( *p )) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Inserts a new element at last segment of the queue, move semantics
+ bool enqueue( value_type&& val )
+ {
+ scoped_node_ptr p( alloc_node_move( std::move( val )));
+ if ( base_class::enqueue( *p )) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Enqueues data to the queue using a functor
+ /**
+ \p Func is a functor called to create node.
+ The functor \p f takes one argument - a reference to a new node of type \ref value_type :
+ \code
+ cds::container::SegmentedQueue< cds::gc::HP, Foo > myQueue;
+ Bar bar;
+ myQueue.enqueue_with( [&bar]( Foo& dest ) { dest = bar; } );
+ \endcode
+ */
+ template <typename Func>
+ bool enqueue_with( Func f )
+ {
+ scoped_node_ptr p( alloc_node());
+ f( *p );
+ if ( base_class::enqueue( *p )) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+
+ /// Synonym for \p enqueue( value_type const& ) member function
+ bool push( value_type const& val )
+ {
+ return enqueue( val );
+ }
+
+ /// Synonym for \p enqueue( value_type&& ) member function
+ bool push( value_type&& val )
+ {
+ return enqueue( std::move( val ));
+ }
+
+ /// Synonym for \p enqueue_with() member function
+ template <typename Func>
+ bool push_with( Func f )
+ {
+ return enqueue_with( f );
+ }
+
+ /// Enqueues data of type \ref value_type constructed with <tt>std::forward<Args>(args)...</tt>
+ template <typename... Args>
+ bool emplace( Args&&... args )
+ {
+ scoped_node_ptr p( alloc_node_move( std::forward<Args>(args)... ));
+ if ( base_class::enqueue( *p )) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Dequeues a value from the queue
+ /**
+ If queue is not empty, the function returns \p true, \p dest contains copy of
+ dequeued value. The assignment operator for type \ref value_type is invoked.
+ If queue is empty, the function returns \p false, \p dest is unchanged.
+ */
+ bool dequeue( value_type& dest )
+ {
+ return dequeue_with( [&dest]( value_type& src ) { dest = std::move( src );});
+ }
+
+ /// Dequeues a value using a functor
+ /**
+ \p Func is a functor called to copy dequeued value.
+ The functor takes one argument - a reference to removed node:
+ \code
+ cds:container::MSQueue< cds::gc::HP, Foo > myQueue;
+ Bar bar;
+ myQueue.dequeue_with( [&bar]( Foo& src ) { bar = std::move( src );});
+ \endcode
+ The functor is called only if the queue is not empty.
+ */
+ template <typename Func>
+ bool dequeue_with( Func f )
+ {
+ value_type * p = base_class::dequeue();
+ if ( p ) {
+ f( *p );
+ gc::template retire< typename maker::node_disposer >( p );
+ return true;
+ }
+ return false;
+ }
+
+ /// Synonym for \p dequeue_with() function
+ template <typename Func>
+ bool pop_with( Func f )
+ {
+ return dequeue_with( f );
+ }
+
+ /// Synonym for \p dequeue() function
+ bool pop( value_type& dest )
+ {
+ return dequeue( dest );
+ }
+
+ /// Checks if the queue is empty
+ /**
+ The original segmented queue algorithm does not allow to check emptiness accurately
+ because \p empty() is unlinearizable.
+ This function tests queue's emptiness checking <tt>size() == 0</tt>,
+ so, the item counting feature is an essential part of queue's algorithm.
+ */
+ bool empty() const
+ {
+ return base_class::empty();
+ }
+
+ /// Clear the queue
+ /**
+ 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()
+ {
+ base_class::clear();
+ }
+
+ /// Returns queue's item count
+ size_t size() const
+ {
+ return base_class::size();
+ }
+
+ /// Returns reference to internal statistics
+ /**
+ The type of internal statistics is specified by \p Traits template argument.
+ */
+ const stat& statistics() const
+ {
+ return base_class::statistics();
+ }
+
+ /// Returns quasi factor, a power-of-two number
+ size_t quasi_factor() const
+ {
+ return base_class::quasi_factor();
+ }
+ };
+
+}} // namespace cds::container
+
+#endif // #ifndef CDSLIB_CONTAINER_SEGMENTED_QUEUE_H
projects / c11concurrency-benchmarks.git / blobdiff