godot/core/os/thread_work_pool.h
Rémi Verschelde 1426cd3b3a
One Copyright Update to rule them all
As many open source projects have started doing it, we're removing the
current year from the copyright notice, so that we don't need to bump
it every year.

It seems like only the first year of publication is technically
relevant for copyright notices, and even that seems to be something
that many companies stopped listing altogether (in a version controlled
codebase, the commits are a much better source of date of publication
than a hardcoded copyright statement).

We also now list Godot Engine contributors first as we're collectively
the current maintainers of the project, and we clarify that the
"exclusive" copyright of the co-founders covers the timespan before
opensourcing (their further contributions are included as part of Godot
Engine contributors).

Also fixed "cf." Frenchism - it's meant as "refer to / see".

Backported from #70885.
2023-01-10 15:26:54 +01:00

158 lines
5.2 KiB
C++

/**************************************************************************/
/* thread_work_pool.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#ifndef THREAD_WORK_POOL_H
#define THREAD_WORK_POOL_H
#include "core/os/memory.h"
#include "core/os/semaphore.h"
#include "core/os/thread.h"
#include <atomic>
class ThreadWorkPool {
std::atomic<uint32_t> index;
struct BaseWork {
std::atomic<uint32_t> *index = nullptr;
uint32_t max_elements = 0;
virtual void work() = 0;
virtual ~BaseWork() = default;
};
template <class C, class M, class U>
struct Work : public BaseWork {
C *instance;
M method;
U userdata;
virtual void work() override {
while (true) {
uint32_t work_index = index->fetch_add(1, std::memory_order_relaxed);
if (work_index >= max_elements) {
break;
}
(instance->*method)(work_index, userdata);
}
}
};
struct ThreadData {
Thread thread;
Semaphore start;
Semaphore completed;
std::atomic<bool> exit;
BaseWork *work = nullptr;
};
ThreadData *threads = nullptr;
uint32_t thread_count = 0;
uint32_t threads_working = 0;
BaseWork *current_work = nullptr;
static void _thread_function(void *p_user);
public:
template <class C, class M, class U>
void begin_work(uint32_t p_elements, C *p_instance, M p_method, U p_userdata) {
ERR_FAIL_COND(!threads); //never initialized
ERR_FAIL_COND(current_work != nullptr);
index.store(0, std::memory_order_release);
Work<C, M, U> *w = memnew((Work<C, M, U>));
w->instance = p_instance;
w->userdata = p_userdata;
w->method = p_method;
w->index = &index;
w->max_elements = p_elements;
current_work = w;
threads_working = MIN(p_elements, thread_count);
for (uint32_t i = 0; i < threads_working; i++) {
threads[i].work = w;
threads[i].start.post();
}
}
bool is_working() const {
return current_work != nullptr;
}
bool is_done_dispatching() const {
ERR_FAIL_COND_V(current_work == nullptr, true);
return index.load(std::memory_order_acquire) >= current_work->max_elements;
}
uint32_t get_work_index() const {
ERR_FAIL_COND_V(current_work == nullptr, 0);
uint32_t idx = index.load(std::memory_order_acquire);
return MIN(idx, current_work->max_elements);
}
void end_work() {
ERR_FAIL_COND(current_work == nullptr);
for (uint32_t i = 0; i < threads_working; i++) {
threads[i].completed.wait();
threads[i].work = nullptr;
}
threads_working = 0;
memdelete(current_work);
current_work = nullptr;
}
template <class C, class M, class U>
void do_work(uint32_t p_elements, C *p_instance, M p_method, U p_userdata) {
switch (p_elements) {
case 0:
// Nothing to do, so do nothing.
break;
case 1:
// No value in pushing the work to another thread if it's a single job
// and we're going to wait for it to finish. Just run it right here.
(p_instance->*p_method)(0, p_userdata);
break;
default:
// Multiple jobs to do; commence threaded business.
begin_work(p_elements, p_instance, p_method, p_userdata);
end_work();
}
}
_FORCE_INLINE_ int get_thread_count() const { return thread_count; }
void init(int p_thread_count = -1);
void finish();
~ThreadWorkPool();
};
#endif // THREAD_WORK_POOL_H