mirror of
https://github.com/vcmi/vcmi.git
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Ivan Savenko
65 lines
1.9 KiB
C++
65 lines
1.9 KiB
C++
/*
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* AsyncRunner.h, part of VCMI engine
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*
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* Authors: listed in file AUTHORS in main folder
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*
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* License: GNU General Public License v2.0 or later
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* Full text of license available in license.txt file, in main folder
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*
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*/
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#pragma once
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#include <tbb/task_arena.h>
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#include <tbb/task_group.h>
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#include <tbb/global_control.h>
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VCMI_LIB_NAMESPACE_BEGIN
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/// Helper class for running asynchronous tasks using TBB thread pool
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class AsyncRunner : boost::noncopyable
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{
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tbb::task_arena arena;
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tbb::task_group taskGroup;
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tbb::global_control control;
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static int selectArenaSize()
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{
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// WARNING:
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// Due to blocking waits in AI logic, we require some oversubscription on system with small number of cores
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// othervice, it is possible for AI threads to stuck in blocking wait, while task that will unblock AI never assigned to worker thread
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// TBB provides resumable tasks support, however this support is not available on all systems (most notably - Android)
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// To work around this problem, request TBB to create few extra threads when running on CPU with low max concurrency
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// Issue confirmed to happen (but likely not limited to) on iPhone 12 Pro (2+4 cores) and on virtual systems with 2 cores
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int cores = tbb::this_task_arena::max_concurrency();
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int requiredWorkersCount = 4;
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return std::max(cores, requiredWorkersCount);
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}
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public:
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AsyncRunner()
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:arena(selectArenaSize())
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,control(tbb::global_control::max_allowed_parallelism, selectArenaSize())
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{}
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/// Runs the provided functor asynchronously on a thread from the TBB worker pool.
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template<typename Functor>
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void run(Functor && f)
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{
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arena.enqueue(taskGroup.defer(std::forward<Functor>(f)));
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}
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/// Waits for all previously enqueued task.
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/// Re-entrable - waiting for tasks does not prevent submitting new tasks
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void wait()
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{
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taskGroup.wait();
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}
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~AsyncRunner()
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{
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wait();
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}
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};
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VCMI_LIB_NAMESPACE_END
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