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457 lines
18 KiB
C
457 lines
18 KiB
C
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// Copyright (c) 2006-2018 Maxim Khizhinsky
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef CDSLIB_CONTAINER_BASKET_QUEUE_H
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#define CDSLIB_CONTAINER_BASKET_QUEUE_H
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#include <cds/intrusive/basket_queue.h>
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#include <cds/container/details/base.h>
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#include <memory>
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namespace cds { namespace container {
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/// BasketQueue related definitions
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/** @ingroup cds_nonintrusive_helper
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*/
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namespace basket_queue {
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/// Internal statistics
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template <typename Counter = cds::intrusive::basket_queue::stat<>::counter_type >
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using stat = cds::intrusive::basket_queue::stat< Counter >;
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/// Dummy internal statistics
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typedef cds::intrusive::basket_queue::empty_stat empty_stat;
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/// BasketQueue default type traits
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struct traits
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{
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/// Node allocator
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typedef CDS_DEFAULT_ALLOCATOR allocator;
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/// Back-off strategy
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typedef cds::backoff::empty back_off;
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/// Item counting feature; by default, disabled. Use \p cds::atomicity::item_counter to enable item counting
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typedef atomicity::empty_item_counter item_counter;
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/// Internal statistics (by default, disabled)
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/**
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Possible option value are: \p basket_queue::stat, \p basket_queue::empty_stat (the default),
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user-provided class that supports \p %basket_queue::stat interface.
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*/
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typedef basket_queue::empty_stat stat;
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/// C++ memory ordering model
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/**
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Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
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or \p opt::v::sequential_consistent (sequentially consisnent memory model).
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*/
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typedef opt::v::relaxed_ordering memory_model;
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/// Padding for internal critical atomic data. Default is \p opt::cache_line_padding
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enum { padding = opt::cache_line_padding };
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};
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/// Metafunction converting option list to \p basket_queue::traits
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/**
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Supported \p Options are:
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- \p opt::allocator - allocator (like \p std::allocator) used for allocating queue nodes. Default is \ref CDS_DEFAULT_ALLOCATOR
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- \p opt::back_off - back-off strategy used, default is \p cds::backoff::empty.
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- \p opt::item_counter - the type of item counting feature. Default is \p cds::atomicity::empty_item_counter (item counting disabled)
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To enable item counting use \p cds::atomicity::item_counter
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- \ opt::stat - the type to gather internal statistics.
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Possible statistics types are: \p basket_queue::stat, \p basket_queue::empty_stat, user-provided class that supports \p %basket_queue::stat interface.
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Default is \p %basket_queue::empty_stat.
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- \p opt::padding - padding for internal critical atomic data. Default is \p opt::cache_line_padding
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- \p opt::memory_model - C++ memory ordering model. Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
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or \p opt::v::sequential_consistent (sequentially consisnent memory model).
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Example: declare \p %BasketQueue with item counting and internal statistics
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\code
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typedef cds::container::BasketQueue< cds::gc::HP, Foo,
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typename cds::container::basket_queue::make_traits<
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cds::opt::item_counte< cds::atomicity::item_counter >,
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cds::opt::stat< cds::intrusive::basket_queue::stat<> >
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>::type
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> myQueue;
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\endcode
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*/
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template <typename... Options>
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struct make_traits {
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# ifdef CDS_DOXYGEN_INVOKED
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typedef implementation_defined type; ///< Metafunction result
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# else
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typedef typename cds::opt::make_options<
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typename cds::opt::find_type_traits< traits, Options... >::type
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, Options...
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>::type type;
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# endif
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};
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} // namespace basket_queue
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//@cond
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namespace details {
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template <typename GC, typename T, typename Traits>
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struct make_basket_queue
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{
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typedef GC gc;
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typedef T value_type;
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typedef Traits traits;
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struct node_type: public intrusive::basket_queue::node< gc >
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{
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value_type m_value;
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node_type( const value_type& val )
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: m_value( val )
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{}
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template <typename... Args>
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node_type( Args&&... args )
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: m_value( std::forward<Args>(args)...)
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{}
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};
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typedef typename std::allocator_traits< typename traits::allocator >::template rebind_alloc< node_type > allocator_type;
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//typedef typename traits::allocator::template rebind<node_type>::other allocator_type;
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typedef cds::details::Allocator< node_type, allocator_type > cxx_allocator;
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struct node_deallocator
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{
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void operator ()( node_type * pNode )
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{
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cxx_allocator().Delete( pNode );
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}
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};
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struct intrusive_traits : public traits
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{
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typedef cds::intrusive::basket_queue::base_hook< opt::gc<gc> > hook;
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typedef node_deallocator disposer;
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static constexpr const cds::intrusive::opt::link_check_type link_checker = cds::intrusive::basket_queue::traits::link_checker;
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};
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typedef cds::intrusive::BasketQueue< gc, node_type, intrusive_traits > type;
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};
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}
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//@endcond
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/// Basket lock-free queue (non-intrusive variant)
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/** @ingroup cds_nonintrusive_queue
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It is non-intrusive version of basket queue algorithm based on intrusive::BasketQueue counterpart.
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\par Source:
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[2007] Moshe Hoffman, Ori Shalev, Nir Shavit "The Baskets Queue"
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<b>Key idea</b>
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In the 'basket' approach, instead of
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the traditional ordered list of nodes, the queue consists of an ordered list of groups
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of nodes (logical baskets). The order of nodes in each basket need not be specified, and in
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fact, it is easiest to maintain them in LIFO order. The baskets fulfill the following basic
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rules:
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- Each basket has a time interval in which all its nodes' enqueue operations overlap.
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- The baskets are ordered by the order of their respective time intervals.
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- For each basket, its nodes' dequeue operations occur after its time interval.
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- The dequeue operations are performed according to the order of baskets.
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Two properties define the FIFO order of nodes:
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- The order of nodes in a basket is not specified.
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- The order of nodes in different baskets is the FIFO-order of their respective baskets.
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In algorithms such as the MS-queue or optimistic
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queue, threads enqueue items by applying a Compare-and-swap (CAS) operation to the
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queue's tail pointer, and all the threads that fail on a particular CAS operation (and also
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the winner of that CAS) overlap in time. In particular, they share the time interval of
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the CAS operation itself. Hence, all the threads that fail to CAS on the tail-node of
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the queue may be inserted into the same basket. By integrating the basket-mechanism
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as the back-off mechanism, the time usually spent on backing-off before trying to link
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onto the new tail, can now be utilized to insert the failed operations into the basket,
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allowing enqueues to complete sooner. In the meantime, the next successful CAS operations
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by enqueues allow new baskets to be formed down the list, and these can be
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filled concurrently. Moreover, the failed operations don't retry their link attempt on the
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new tail, lowering the overall contention on it. This leads to a queue
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algorithm that unlike all former concurrent queue algorithms requires virtually no tuning
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of the backoff mechanisms to reduce contention, making the algorithm an attractive
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out-of-the-box queue.
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In order to enqueue, just as in MSQueue, a thread first tries to link the new node to
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the last node. If it failed to do so, then another thread has already succeeded. Thus it
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tries to insert the new node into the new basket that was created by the winner thread.
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To dequeue a node, a thread first reads the head of the queue to obtain the
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oldest basket. It may then dequeue any node in the oldest basket.
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Template arguments:
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- \p GC - garbage collector type: \p gc::HP, \p gc::DHP
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- \p T - type of value to be stored in the queue
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- \p Traits - queue traits, default is \p basket_queue::traits. You can use \p basket_queue::make_traits
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metafunction to make your traits or just derive your traits from \p %basket_queue::traits:
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\code
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struct myTraits: public cds::container::basket_queue::traits {
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typedef cds::intrusive::basket_queue::stat<> stat;
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typedef cds::atomicity::item_counter item_counter;
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};
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typedef cds::container::BasketQueue< cds::gc::HP, Foo, myTraits > myQueue;
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// Equivalent make_traits example:
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typedef cds::container::BasketQueue< cds::gc::HP, Foo,
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typename cds::container::basket_queue::make_traits<
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cds::opt::stat< cds::container::basket_queue::stat<> >,
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cds::opt::item_counter< cds::atomicity::item_counter >
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>::type
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> myQueue;
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\endcode
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*/
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template <typename GC, typename T, typename Traits = basket_queue::traits >
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class BasketQueue:
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#ifdef CDS_DOXYGEN_INVOKED
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private intrusive::BasketQueue< GC, intrusive::basket_queue::node< T >, Traits >
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#else
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protected details::make_basket_queue< GC, T, Traits >::type
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#endif
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{
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//@cond
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typedef details::make_basket_queue< GC, T, Traits > maker;
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typedef typename maker::type base_class;
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//@endcond
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public:
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/// Rebind template arguments
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template <typename GC2, typename T2, typename Traits2>
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struct rebind {
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typedef BasketQueue< GC2, T2, Traits2> other ; ///< Rebinding result
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};
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public:
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typedef GC gc; ///< Garbage collector
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typedef T value_type; ///< Type of value to be stored in the queue
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typedef Traits traits; ///< Queue's traits
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typedef typename base_class::back_off back_off; ///< Back-off strategy used
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typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
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typedef typename base_class::item_counter item_counter; ///< Item counting policy used
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typedef typename base_class::stat stat; ///< Internal statistics policy used
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typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
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static constexpr const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount; ///< Count of hazard pointer required for the algorithm
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protected:
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typedef typename maker::node_type node_type; ///< queue node type (derived from intrusive::basket_queue::node)
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//@cond
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typedef typename maker::cxx_allocator cxx_allocator;
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typedef typename maker::node_deallocator node_deallocator; // deallocate node
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typedef typename base_class::node_traits node_traits;
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//@endcond
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protected:
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///@cond
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static node_type * alloc_node()
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{
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return cxx_allocator().New();
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}
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static node_type * alloc_node( const value_type& val )
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{
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return cxx_allocator().New( val );
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}
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template <typename... Args>
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static node_type * alloc_node_move( Args&&... args )
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{
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return cxx_allocator().MoveNew( std::forward<Args>( args )... );
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}
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static void free_node( node_type * p )
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{
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node_deallocator()( p );
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}
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struct node_disposer {
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void operator()( node_type * pNode )
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{
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free_node( pNode );
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}
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};
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typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
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//@endcond
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public:
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/// Initializes empty queue
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BasketQueue()
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{}
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/// Destructor clears the queue
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~BasketQueue()
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{}
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/// Enqueues \p val value into the queue.
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/**
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The function makes queue node in dynamic memory calling copy constructor for \p val
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and then it calls \p intrusive::BasketQueue::enqueue().
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Returns \p true if success, \p false otherwise.
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*/
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bool enqueue( value_type const& val )
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{
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scoped_node_ptr p( alloc_node(val));
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if ( base_class::enqueue( *p )) {
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p.release();
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return true;
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}
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return false;
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}
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/// Enqueues \p val value into the queue, move semantics
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bool enqueue( value_type&& val )
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{
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scoped_node_ptr p( alloc_node_move( std::move( val )));
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if ( base_class::enqueue( *p )) {
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p.release();
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return true;
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}
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return false;
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}
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/// Enqueues \p data to queue using a functor
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/**
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\p Func is a functor called to create node.
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The functor \p f takes one argument - a reference to a new node of type \ref value_type :
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\code
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cds::container::BasketQueue< cds::gc::HP, Foo > myQueue;
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Bar bar;
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myQueue.enqueue_with( [&bar]( Foo& dest ) { dest = bar; } );
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\endcode
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*/
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template <typename Func>
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bool enqueue_with( Func f )
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{
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scoped_node_ptr p( alloc_node());
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f( p->m_value );
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if ( base_class::enqueue( *p )) {
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p.release();
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return true;
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}
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return false;
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}
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/// Synonym for \p enqueue() function
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bool push( value_type const& val )
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{
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return enqueue( val );
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}
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/// Synonym for \p enqueue() function, move semantics
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bool push( value_type&& val )
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{
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return enqueue( std::move( val ));
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}
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/// Synonym for \p enqueue_with() function
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template <typename Func>
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bool push_with( Func f )
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{
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return enqueue_with( f );
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}
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/// 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 \p 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 ) {
|
||
|
|
// TSan finds a race between this read of \p src and node_type constructor
|
||
|
|
// I think, it is wrong
|
||
|
|
CDS_TSAN_ANNOTATE_IGNORE_READS_BEGIN;
|
||
|
|
dest = std::move( src );
|
||
|
|
CDS_TSAN_ANNOTATE_IGNORE_READS_END;
|
||
|
|
});
|
||
|
|
}
|
||
|
|
|
||
|
|
/// 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::BasketQueue< 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 )
|
||
|
|
{
|
||
|
|
typename base_class::dequeue_result res;
|
||
|
|
if ( base_class::do_dequeue( res, true )) {
|
||
|
|
f( node_traits::to_value_ptr( *res.pNext )->m_value );
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
/// 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 the queue is empty
|
||
|
|
/**
|
||
|
|
Note that this function is not \p const.
|
||
|
|
The function is based on \p dequeue() algorithm.
|
||
|
|
*/
|
||
|
|
bool empty()
|
||
|
|
{
|
||
|
|
return base_class::empty();
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Clear the queue
|
||
|
|
/**
|
||
|
|
The function repeatedly calls \ref dequeue until it returns \p nullptr.
|
||
|
|
*/
|
||
|
|
void clear()
|
||
|
|
{
|
||
|
|
base_class::clear();
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Returns queue's item count
|
||
|
|
/** \copydetails cds::intrusive::BasketQueue::size()
|
||
|
|
*/
|
||
|
|
size_t size() const
|
||
|
|
{
|
||
|
|
return base_class::size();
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Returns reference to internal statistics
|
||
|
|
const stat& statistics() const
|
||
|
|
{
|
||
|
|
return base_class::statistics();
|
||
|
|
}
|
||
|
|
|
||
|
|
};
|
||
|
|
|
||
|
|
}} // namespace cds::container
|
||
|
|
|
||
|
|
#endif // #ifndef CDSLIB_CONTAINER_BASKET_QUEUE_H
|