obs-StreamFX/source/util-threadpool.cpp

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/*
* Modern effects for a modern Streamer
* Copyright (C) 2020 Michael Fabian Dirks
*
* This program 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include "util-threadpool.hpp"
#include "common.hpp"
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#include <cstddef>
#define LOCAL_PREFIX "<util::threadpool> "
// Most Tasks likely wait for IO, so we can use that time for other tasks.
#define CONCURRENCY_MULTIPLIER 2
util::threadpool::threadpool() : _workers(), _worker_stop(false), _worker_idx(0), _tasks(), _tasks_lock(), _tasks_cv()
{
std::size_t concurrency = static_cast<size_t>(std::thread::hardware_concurrency() * CONCURRENCY_MULTIPLIER);
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for (std::size_t n = 0; n < concurrency; n++) {
_workers.emplace_back(std::bind(&util::threadpool::work, this));
}
}
util::threadpool::~threadpool()
{
_worker_stop = true;
_tasks_cv.notify_all();
for (auto& thread : _workers) {
_tasks_cv.notify_all();
if (thread.joinable()) {
thread.join();
}
}
}
std::shared_ptr<::util::threadpool::task> util::threadpool::push(threadpool_callback_t fn, threadpool_data_t data)
{
auto task = std::make_shared<util::threadpool::task>(fn, data);
std::unique_lock<std::mutex> lock(_tasks_lock);
_tasks.emplace_back(task);
_tasks_cv.notify_one();
return task;
}
void util::threadpool::pop(std::shared_ptr<::util::threadpool::task> work)
{
if (work) {
work->_is_dead.store(true);
}
}
void util::threadpool::work()
{
std::shared_ptr<util::threadpool::task> local_work{};
uint32_t local_number = _worker_idx.fetch_add(1);
while (!_worker_stop) {
// Wait for more work, or immediately continue if there is still work to do.
{
// Lock the tasks mutex to check for work.
std::unique_lock<std::mutex> lock(_tasks_lock);
// If there are currently no tasks queued, wait on the condition variable.
// This temporarily unlocks the mutex until it is woken up.
if (_tasks.size() == 0) {
_tasks_cv.wait(lock, [this]() { return _worker_stop || _tasks.size() > 0; });
}
// If there is either no tasks or we were asked to stop, skip everything.
if (_worker_stop || (_tasks.size() == 0)) {
continue;
}
// Grab the latest task and immediately remove it from the queue.
local_work = _tasks.front();
_tasks.pop_front();
}
// If the task was killed, skip everything again.
if (local_work->_is_dead) {
continue;
}
// Try to execute work, but don't crash on catchable exceptions.
if (local_work->_callback) {
try {
local_work->_callback(local_work->_data);
} catch (std::exception const& ex) {
DLOG_WARNING(LOCAL_PREFIX "Worker %lX caught exception from task (%tX, %tX) with message: %s",
local_number, local_work->_callback.target<ptrdiff_t>(),
reinterpret_cast<ptrdiff_t>(local_work->_data.get()), ex.what());
} catch (...) {
DLOG_WARNING(LOCAL_PREFIX "Worker %lX caught exception of unknown type from task (%tX, %tX).",
local_number, local_work->_callback.target<ptrdiff_t>(),
reinterpret_cast<ptrdiff_t>(local_work->_data.get()));
}
}
}
_worker_idx.fetch_sub(1);
}
util::threadpool::task::task() {}
util::threadpool::task::task(threadpool_callback_t fn, threadpool_data_t dt) : _is_dead(false), _callback(fn), _data(dt)
{}