OpenTTD-patches/src/thread.h
Patric Stout b45c006ab9
Fix: on startup, NewGRF scan could case race-condition (#9382)
Creating a thread was not thread-safe. The irony.

The video-driver has a function GameLoopPause() which first checks
if the thread is the game-thread or not. For this it needs access
to this->game_thread. This variable is set in StartNewThread().

However, due to timing, it is well possible GameLoopPause() is
called from the thread well before this->game_thread is assigned.

And so we have a race-condition!

Simply solve this by preventing a thread to start till we are
done with our bookkeeping.
2021-06-17 20:10:40 +02:00

88 lines
2.7 KiB
C++

/*
* This file is part of OpenTTD.
* 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.
* 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.
* 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/>.
*/
/** @file thread.h Base of all threads. */
#ifndef THREAD_H
#define THREAD_H
#include "debug.h"
#include "crashlog.h"
#include <system_error>
#include <thread>
#include <mutex>
/**
* Sleep on the current thread for a defined time.
* @param milliseconds Time to sleep for in milliseconds.
*/
inline void CSleep(int milliseconds)
{
std::this_thread::sleep_for(std::chrono::milliseconds(milliseconds));
}
/**
* Name the thread this function is called on for the debugger.
* @param name Name to set for the thread..
*/
void SetCurrentThreadName(const char *name);
/**
* Start a new thread.
* @tparam TFn Type of the function to call on the thread.
* @tparam TArgs Type of the parameters of the thread function.
* @param thr Pointer to a thread object; may be \c nullptr if a detached thread is wanted.
* @param name Name of the thread.
* @param _Fx Function to call on the thread.
* @param _Ax Arguments for the thread function.
* @return True if the thread was successfully started, false otherwise.
*/
template<class TFn, class... TArgs>
inline bool StartNewThread(std::thread *thr, const char *name, TFn&& _Fx, TArgs&&... _Ax)
{
#ifndef NO_THREADS
try {
static std::mutex thread_startup_mutex;
std::lock_guard<std::mutex> lock(thread_startup_mutex);
std::thread t([] (const char *name, TFn&& F, TArgs&&... A) {
/* Delay starting the thread till the main thread is finished
* with the administration. This prevent race-conditions on
* startup. */
{
std::lock_guard<std::mutex> lock(thread_startup_mutex);
}
SetCurrentThreadName(name);
CrashLog::InitThread();
try {
/* Call user function with the given arguments. */
F(A...);
} catch (...) {
NOT_REACHED();
}
}, name, std::forward<TFn>(_Fx), std::forward<TArgs>(_Ax)...);
if (thr != nullptr) {
*thr = std::move(t);
} else {
t.detach();
}
return true;
} catch (const std::system_error& e) {
/* Something went wrong, the system we are running on might not support threads. */
Debug(misc, 1, "Can't create thread '{}': {}", name, e.what());
}
#endif
return false;
}
#endif /* THREAD_H */