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244c539a2e
scheduler and setting it with set_scheduling_algorithm(). Document sched_algorithm interface class. Fix the example in condition_variables.qbk to explicitly unlock 'lk' before calling process_data().
85 lines
2.3 KiB
Plaintext
85 lines
2.3 KiB
Plaintext
[/
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Copyright Oliver Kowalke 2013.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt
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]
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[section:scheduling Scheduling]
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Fibers are managed by a scheduler which coordinates the sequence of fibers
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running or waiting.
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Each thread is required to have its own scheduler. By default, __boost_fiber__
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allocates for each thread a scheduler ([class_link round_robin]) on the
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heap.
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To prevent the library from heap-allocating a default scheduler for a given
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thread, that thread must call [function_link set_scheduling_algorithm] before
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any other __boost_fiber__ entry point.
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void thread_fn()
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{
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my_fiber_scheduler mfs;
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boost::fibers::set_scheduling_algorithm( & mfs);
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...
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}
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A fiber-scheduler must implement interface __algo__. __boost_fiber__ provides one
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scheduler: [class_link round_robin].
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You are explicitly permitted to code your own __algo__ subclass, and to pass
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it to [function_link set_scheduling_algorithm].
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[class_heading sched_algorithm]
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#include <boost/fiber/algorithm.hpp>
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struct sched_algorithm
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{
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virtual ~sched_algorithm() {}
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virtual void awakened( detail::worker_fiber *) = 0;
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virtual detail::worker_fiber * pick_next() = 0;
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virtual void priority( detail::worker_fiber *, int) noexcept = 0;
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};
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[member_heading sched_algorithm..awakened]
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virtual void awakened( detail::worker_fiber * f) = 0;
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[variablelist
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[[Effects:] [Marks fiber `f`, to be ready to run.]]
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]
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[member_heading sched_algorithm..pick_next]
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virtual detail::worker_fiber * pick_next() = 0;
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[variablelist
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[[Effects:] [Depending on the scheduling algorithm, this function returns the
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fiber which is to be resumed next.]]
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]
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[member_heading sched_algorithm..priority]
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virtual void priority( detail::worker_fiber *, int) noexcept = 0;
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[variablelist
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[[Effects:] [Resets the priority of fiber `f`.]]
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]
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[class_heading round_robin]
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This class implements __algo__ and schedules fibers in round-robin fashion
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(ignores `fiber::priority()`).
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[info The example section provides a scheduler used for migrating fibers
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(work-stealing) between threads (different schedulers).]
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[endsect]
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