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/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file worker_thread.cpp Worker thread pool utility. */
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#include "stdafx.h"
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#include "worker_thread.h"
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#include "thread.h"
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#include "safeguards.h"
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WorkerThreadPool _general_worker_pool;
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void WorkerThreadPool::Start(const char *thread_name, uint max_workers)
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{
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uint cpus = std::thread::hardware_concurrency();
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if (cpus <= 1) return;
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std::lock_guard<std::mutex> lk(this->lock);
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this->exit = false;
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uint worker_target = std::min<uint>(max_workers, cpus);
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if (this->workers >= worker_target) return;
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uint new_workers = worker_target - this->workers;
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for (uint i = 0; i < new_workers; i++) {
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this->workers++;
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if (!StartNewThread(nullptr, thread_name, &WorkerThreadPool::Run, this)) {
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this->workers--;
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return;
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}
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}
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}
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void WorkerThreadPool::Stop()
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{
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std::unique_lock<std::mutex> lk(this->lock);
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this->exit = true;
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this->worker_wait_cv.notify_all();
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this->done_cv.wait(lk, [this]() { return this->workers == 0; });
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}
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void WorkerThreadPool::EnqueueJob(WorkerJobFunc *func, void *data1, void *data2, void *data3)
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{
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std::unique_lock<std::mutex> lk(this->lock);
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if (this->workers == 0) {
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/* Just execute it here and now */
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lk.unlock();
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func(data1, data2, data3);
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return;
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}
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bool notify = this->jobs.size() < (size_t)this->workers_waiting;
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this->jobs.push({ func, data1, data2, data3 });
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lk.unlock();
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if (notify) this->worker_wait_cv.notify_one();
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}
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void WorkerThreadPool::Run(WorkerThreadPool *pool)
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{
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std::unique_lock<std::mutex> lk(pool->lock);
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while (!pool->exit || !pool->jobs.empty()) {
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if (pool->jobs.empty()) {
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pool->workers_waiting++;
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pool->worker_wait_cv.wait(lk);
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pool->workers_waiting--;
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} else {
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WorkerJob job = pool->jobs.front();
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pool->jobs.pop();
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lk.unlock();
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job.func(job.data1, job.data2, job.data3);
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lk.lock();
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}
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}
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pool->workers--;
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if (pool->workers == 0) {
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pool->done_cv.notify_all();
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}
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}
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