--- /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_RWQUEUE_H
+#define CDSLIB_CONTAINER_RWQUEUE_H
+
+#include <mutex> // unique_lock
+#include <cds/sync/spinlock.h>
+#include <cds/opt/options.h>
+#include <cds/details/allocator.h>
+
+namespace cds { namespace container {
+ /// RWQueue related definitions
+ /** @ingroup cds_nonintrusive_helper
+ */
+ namespace rwqueue {
+ /// RWQueue default type traits
+ struct traits
+ {
+ /// Lock policy
+ typedef cds::sync::spin lock_type;
+
+ /// Node allocator
+ typedef CDS_DEFAULT_ALLOCATOR allocator;
+
+ /// Item counting feature; by default, disabled. Use \p cds::atomicity::item_counter to enable item counting
+ typedef cds::atomicity::empty_item_counter item_counter;
+
+ /// Padding for internal critical atomic data. Default is \p opt::cache_line_padding
+ enum { padding = opt::cache_line_padding };
+ };
+
+ /// Metafunction converting option list to \p rwqueue::traits
+ /**
+ Supported \p Options are:
+ - opt::lock_type - lock policy, default is \p cds::sync::spin. Any type satisfied \p Mutex C++ concept may be used.
+ - opt::allocator - allocator (like \p std::allocator) used for allocating queue nodes. Default is \ref CDS_DEFAULT_ALLOCATOR
+ - opt::item_counter - the type of item counting feature. Default is \p cds::atomicity::empty_item_counter (item counting disabled)
+ To enable item counting use \p cds::atomicity::item_counter.
+ - \p opt::padding - padding for internal critical data. Default is \p opt::cache_line_padding
+
+ Example: declare mutex-based \p %RWQueue with item counting
+ \code
+ typedef cds::container::RWQueue< Foo,
+ typename cds::container::rwqueue::make_traits<
+ cds::opt::item_counter< cds::atomicity::item_counter >,
+ cds::opt::lock_type< std::mutex >
+ >::type
+ > myQueue;
+ \endcode
+ */
+ 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 rwqueue
+
+ /// Michael & Scott blocking queue with fine-grained synchronization schema
+ /** @ingroup cds_nonintrusive_queue
+ The queue has two different locks: one for reading and one for writing.
+ Therefore, one writer and one reader can simultaneously access to the queue.
+ The queue does not require any garbage collector.
+
+ <b>Source</b>
+ - [1998] Maged Michael, Michael Scott "Simple, fast, and practical non-blocking
+ and blocking concurrent queue algorithms"
+
+ <b>Template arguments</b>
+ - \p T - value type to be stored in the queue
+ - \p Traits - queue traits, default is \p rwqueue::traits. You can use \p rwqueue::make_traits
+ metafunction to make your traits or just derive your traits from \p %rwqueue::traits:
+ \code
+ struct myTraits: public cds::container::rwqueue::traits {
+ typedef cds::atomicity::item_counter item_counter;
+ };
+ typedef cds::container::RWQueue< Foo, myTraits > myQueue;
+
+ // Equivalent make_traits example:
+ typedef cds::container::RWQueue< Foo,
+ typename cds::container::rwqueue::make_traits<
+ cds::opt::item_counter< cds::atomicity::item_counter >
+ >::type
+ > myQueue;
+ \endcode
+ */
+ template <typename T, typename Traits = rwqueue::traits >
+ class RWQueue
+ {
+ public:
+ /// Rebind template arguments
+ template <typename T2, typename Traits2>
+ struct rebind {
+ typedef RWQueue< T2, Traits2 > other ; ///< Rebinding result
+ };
+
+ public:
+ typedef T value_type; ///< Type of value to be stored in the queue
+ typedef Traits traits; ///< Queue traits
+
+ typedef typename traits::lock_type lock_type; ///< Locking primitive
+ typedef typename traits::item_counter item_counter; ///< Item counting policy used
+
+ protected:
+ //@cond
+ /// Node type
+ struct node_type
+ {
+ atomics::atomic< node_type *> m_pNext; ///< Pointer to the next node in the queue
+ value_type m_value; ///< Value stored in the node
+
+ node_type( value_type const& v )
+ : m_pNext( nullptr )
+ , m_value(v)
+ {}
+
+ node_type()
+ : m_pNext( nullptr )
+ {}
+
+ template <typename... Args>
+ node_type( Args&&... args )
+ : m_pNext( nullptr )
+ , m_value( std::forward<Args>(args)...)
+ {}
+ };
+ //@endcond
+
+ public:
+ typedef typename traits::allocator::template rebind<node_type>::other allocator_type; ///< Allocator type used for allocate/deallocate the queue nodes
+
+ protected:
+ //@cond
+ typedef std::unique_lock<lock_type> scoped_lock;
+ typedef cds::details::Allocator< node_type, allocator_type > node_allocator;
+
+ struct head_type {
+ mutable lock_type lock;
+ node_type * ptr;
+ };
+
+ head_type m_Head;
+ typename opt::details::apply_padding< head_type, traits::padding >::padding_type pad_;
+ head_type m_Tail;
+
+ item_counter m_ItemCounter;
+ //@endcond
+
+ protected:
+ //@cond
+ static node_type * alloc_node()
+ {
+ return node_allocator().New();
+ }
+
+ static node_type * alloc_node( T const& data )
+ {
+ return node_allocator().New( data );
+ }
+
+ template <typename... Args>
+ static node_type * alloc_node_move( Args&&... args )
+ {
+ return node_allocator().MoveNew( std::forward<Args>( args )... );
+ }
+
+ static void free_node( node_type * pNode )
+ {
+ node_allocator().Delete( pNode );
+ }
+
+ bool enqueue_node( node_type * p )
+ {
+ assert( p != nullptr );
+ {
+ scoped_lock lock( m_Tail.lock );
+ m_Tail.ptr->m_pNext.store( p, atomics::memory_order_release );
+ m_Tail.ptr = p;
+ }
+ ++m_ItemCounter;
+ return true;
+ }
+
+ struct node_disposer {
+ void operator()( node_type * pNode )
+ {
+ free_node( pNode );
+ }
+ };
+ typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
+ //@endcond
+
+ public:
+ /// Makes empty queue
+ RWQueue()
+ {
+ node_type * pNode = alloc_node();
+ m_Head.ptr =
+ m_Tail.ptr = pNode;
+ }
+
+ /// Destructor clears queue
+ ~RWQueue()
+ {
+ clear();
+ assert( m_Head.ptr == m_Tail.ptr );
+ free_node( m_Head.ptr );
+ }
+
+ /// Enqueues \p data. Always return \a true
+ bool enqueue( value_type const& data )
+ {
+ scoped_node_ptr p( alloc_node( data ));
+ if ( enqueue_node( p.get())) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Enqueues \p data, move semantics
+ bool enqueue( value_type&& data )
+ {
+ scoped_node_ptr p( alloc_node_move( std::move( data )));
+ if ( enqueue_node( p.get())) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Enqueues \p 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::RWQueue< 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->m_value );
+ if ( enqueue_node( p.get())) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// 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 ( enqueue_node( p.get())) {
+ p.release();
+ return true;
+ }
+ return false;
+ }
+
+ /// Synonym for \p enqueue( value_type const& ) function
+ bool push( value_type const& val )
+ {
+ return enqueue( val );
+ }
+
+ /// Synonym for \p enqueue( value_type&& ) function
+ bool push( value_type&& val )
+ {
+ return enqueue( std::move( val ));
+ }
+
+ /// Synonym for \p enqueue_with() function
+ template <typename Func>
+ bool push_with( Func f )
+ {
+ return enqueue_with( f );
+ }
+
+ /// Dequeues a value to \p dest.
+ /**
+ If queue is empty returns \a false, \p dest can be corrupted.
+ If queue is not empty returns \a true, \p dest contains the value dequeued
+ */
+ 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::RWQueue< 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 )
+ {
+ node_type * pNode;
+ {
+ scoped_lock lock( m_Head.lock );
+ pNode = m_Head.ptr;
+ node_type * pNewHead = pNode->m_pNext.load( atomics::memory_order_acquire );
+ if ( pNewHead == nullptr )
+ return false;
+ f( pNewHead->m_value );
+ m_Head.ptr = pNewHead;
+ } // unlock here
+ --m_ItemCounter;
+ free_node( pNode );
+ return true;
+ }
+
+ /// Synonym for \p dequeue() function
+ bool pop( value_type& dest )
+ {
+ return dequeue( dest );
+ }
+
+ /// Synonym for \p dequeue_with() function
+ template <typename Func>
+ bool pop_with( Func f )
+ {
+ return dequeue_with( f );
+ }
+
+ /// Checks if queue is empty
+ bool empty() const
+ {
+ scoped_lock lock( m_Head.lock );
+ return m_Head.ptr->m_pNext.load( atomics::memory_order_relaxed ) == nullptr;
+ }
+
+ /// Clears queue
+ void clear()
+ {
+ scoped_lock lockR( m_Head.lock );
+ scoped_lock lockW( m_Tail.lock );
+ while ( m_Head.ptr->m_pNext.load( atomics::memory_order_relaxed ) != nullptr ) {
+ node_type * pHead = m_Head.ptr;
+ m_Head.ptr = m_Head.ptr->m_pNext.load( atomics::memory_order_relaxed );
+ free_node( pHead );
+ }
+ m_ItemCounter.reset();
+ }
+
+ /// Returns queue's item count
+ /**
+ The value returned depends on \p rwqueue::traits::item_counter. For \p atomicity::empty_item_counter,
+ this function always returns 0.
+
+ @note Even if you use real item counter and it returns 0, this fact is not mean that the queue
+ is empty. To check queue emptyness use \p empty() method.
+ */
+ size_t size() const
+ {
+ return m_ItemCounter.value();
+ }
+
+ //@cond
+ /// The class has no internal statistics. For test consistency only
+ std::nullptr_t statistics() const
+ {
+ return nullptr;
+ }
+ //@endcond
+ };
+
+}} // namespace cds::container
+
+#endif // #ifndef CDSLIB_CONTAINER_RWQUEUE_H
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