mirror of
https://github.com/boostorg/fiber.git
synced 2026-02-13 00:12:17 +00:00
cb7b5ddd25
Every sched_algorithm_with_properties<PROPS> subclass awakened() call must ensure that control reaches sched_algorithm_with_properties<PROPS>::awakened() _before_ any logic in the subclass method attempts to access properties. This turns out to be all too easy to forget. So instead, advise subclasses to overrride new awakened_props() method. Base- class method sets things up and then calls awakened_props(). Moreover, when the compiler supports it, sched_algorithm_with_properties<PROPS>::awakened() is now marked 'final' to remind subclass authors to override awakened_props() instead.
82 lines
2.2 KiB
C++
82 lines
2.2 KiB
C++
|
|
// Copyright Oliver Kowalke 2013.
|
|
// Distributed under the Boost Software License, Version 1.0.
|
|
// (See accompanying file LICENSE_1_0.txt or copy at
|
|
// http://www.boost.org/LICENSE_1_0.txt)
|
|
|
|
#include "workstealing_round_robin.hpp"
|
|
|
|
#include <boost/assert.hpp>
|
|
|
|
#ifdef BOOST_HAS_ABI_HEADERS
|
|
# include BOOST_ABI_PREFIX
|
|
#endif
|
|
|
|
workstealing_round_robin::workstealing_round_robin():
|
|
rhead_(0),
|
|
rtail_(&rhead_)
|
|
{}
|
|
|
|
void
|
|
workstealing_round_robin::awakened_props( boost::fibers::fiber_base * f)
|
|
{
|
|
boost::mutex::scoped_lock lk( mtx_);
|
|
// append this fiber_base* to ready queue
|
|
BOOST_ASSERT(! f->nxt_);
|
|
*rtail_ = f;
|
|
rtail_ = &f->nxt_;
|
|
}
|
|
|
|
boost::fibers::fiber_base *
|
|
workstealing_round_robin::pick_next()
|
|
{
|
|
boost::mutex::scoped_lock lk( mtx_);
|
|
boost::fibers::fiber_base * f = 0;
|
|
if ( rhead_ )
|
|
{
|
|
f = rhead_;
|
|
// pop head item from ready queue
|
|
rhead_ = rhead_->nxt_;
|
|
f->nxt_ = 0;
|
|
// if that was the last item, reset tail_
|
|
if (! rhead_)
|
|
rtail_ = &rhead_;
|
|
}
|
|
return f;
|
|
}
|
|
|
|
boost::fibers::fiber
|
|
workstealing_round_robin::steal() BOOST_NOEXCEPT
|
|
{
|
|
boost::mutex::scoped_lock lk( mtx_);
|
|
|
|
// Search the queue for the LAST fiber_base that's willing to migrate,
|
|
// in other words (! thread_affinity).
|
|
boost::fibers::fiber_base ** fp = &rhead_, ** found = 0;
|
|
for ( ; *fp; fp = &(*fp)->nxt_)
|
|
{
|
|
// do not consider any fiber whose thread_affinity is set
|
|
if (! properties(*fp).thread_affinity)
|
|
found = fp;
|
|
}
|
|
if (! found)
|
|
{
|
|
// either the queue is completely empty or all current entries have
|
|
// thread_affinity set
|
|
return boost::fibers::fiber(static_cast<boost::fibers::fiber_base*>(0));
|
|
}
|
|
// We found at least one fiber_base whose thread_affinity is NOT set;
|
|
// *found points to the last of these. Unlink and return it.
|
|
boost::fibers::fiber_base* ret = *found;
|
|
*found = ret->nxt_;
|
|
ret->nxt_ = 0;
|
|
// if that was the last item, reset tail_
|
|
if (! *found)
|
|
rtail_ = &rhead_;
|
|
return boost::fibers::fiber(ret);
|
|
}
|
|
|
|
#ifdef BOOST_HAS_ABI_HEADERS
|
|
# include BOOST_ABI_SUFFIX
|
|
#endif
|