-//$$CDS-header$$
+/*
+ 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_INTRUSIVE_BASKET_QUEUE_H
#define CDSLIB_INTRUSIVE_BASKET_QUEUE_H
/// Metafunction converting option list to \p basket_queue::traits
/**
Supported \p Options are:
-
- - opt::hook - hook used. Possible hooks are: \p basket_queue::base_hook, \p basket_queue::member_hook, \p basket_queue::traits_hook.
+ - \p opt::hook - hook used. Possible hooks are: \p basket_queue::base_hook, \p basket_queue::member_hook, \p basket_queue::traits_hook.
If the option is not specified, \p %basket_queue::base_hook<> is used.
- - opt::back_off - back-off strategy used, default is \p cds::backoff::empty.
- - opt::disposer - the functor used for dispose removed items. Default is \p opt::v::empty_disposer. This option is used
+ - \p opt::back_off - back-off strategy used, default is \p cds::backoff::empty.
+ - \p opt::disposer - the functor used for dispose removed items. Default is \p opt::v::empty_disposer. This option is used
when dequeuing.
- - opt::link_checker - the type of node's link fields checking. Default is \p opt::debug_check_link
- - opt::item_counter - the type of item counting feature. Default is \p cds::atomicity::empty_item_counter (item counting disabled)
+ - \p opt::link_checker - the type of node's link fields checking. Default is \p opt::debug_check_link
+ - \p 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
- - opt::stat - the type to gather internal statistics.
+ - \p opt::stat - the type to gather internal statistics.
Possible statistics types are: \p basket_queue::stat, \p basket_queue::empty_stat, user-provided class that supports \p %basket_queue::stat interface.
Default is \p %basket_queue::empty_stat (internal statistics disabled).
- \p opt::padding - padding for internal critical atomic data. Default is \p opt::cache_line_padding
- - opt::memory_model - C++ memory ordering model. Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
+ - \p opt::memory_model - C++ memory ordering model. Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
or \p opt::v::sequential_consistent (sequentially consisnent memory model).
Example: declare \p %BasketQueue with item counting and internal statistics
of the backoff mechanisms to reduce contention, making the algorithm an attractive
out-of-the-box queue.
- In order to enqueue, just as in MSQueue, a thread first tries to link the new node to
+ In order to enqueue, just as in \p MSQueue, a thread first tries to link the new node to
the last node. If it failed to do so, then another thread has already succeeded. Thus it
tries to insert the new node into the new basket that was created by the winner thread.
To dequeue a node, a thread first reads the head of the queue to obtain the
link_checker::is_empty( pNew );
typename gc::Guard guard;
+ typename gc::Guard gNext;
back_off bkoff;
marked_ptr t;
marked_ptr pNext = t->m_pNext.load(memory_model::memory_order_acquire );
if ( pNext.ptr() == nullptr ) {
- pNew->m_pNext.store( marked_ptr(), memory_model::memory_order_release );
+ pNew->m_pNext.store( marked_ptr(), memory_model::memory_order_relaxed );
if ( t->m_pNext.compare_exchange_weak( pNext, marked_ptr(pNew), memory_model::memory_order_release, atomics::memory_order_relaxed )) {
- if ( !m_pTail.compare_exchange_strong( t, marked_ptr(pNew), memory_model::memory_order_release, atomics::memory_order_relaxed ))
+ if ( !m_pTail.compare_exchange_strong( t, marked_ptr(pNew), memory_model::memory_order_release, atomics::memory_order_acquire ))
m_Stat.onAdvanceTailFailed();
break;
}
m_Stat.onTryAddBasket();
// Reread tail next
- typename gc::Guard gNext;
-
try_again:
pNext = gNext.protect( t->m_pNext, []( marked_ptr p ) -> value_type * { return node_traits::to_value_ptr( p.ptr());});
typename gc::template GuardArray<2> g;
g.assign( 0, node_traits::to_value_ptr( pNext.ptr()));
- if ( m_pTail.load( memory_model::memory_order_acquire ) != t
- || t->m_pNext.load( memory_model::memory_order_relaxed ) != pNext )
+ if ( m_pTail.load( memory_model::memory_order_acquire ) != t
+
+ || t->m_pNext.load( memory_model::memory_order_relaxed ) != pNext )
+
{
m_Stat.onEnqueueRace();
bkoff();
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