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Remove: [Video] no longer draw in a thread

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Drawing in a thread is a bit odd, and often leads to surprising
issues. For example, OpenGL would only allow it if you move the
full context to the thread. Which is not always easily done on
all OSes.
In general, the advise is to handle system events and drawing
from the main thread, and do everything else in other threads.
So, let's be more like other games.

Additionally, putting the drawing routine in a thread was only
done for a few targets.

Upcoming commit will move the GameLoop in a thread, which will
work for all targets.
This commit is contained in:
Patric Stout
2021-02-24 15:04:41 +01:00
committed by Patric Stout
parent 56911a86ea
commit 4610aa7ae3
14 changed files with 20 additions and 408 deletions
Download Patch File Download Diff File Expand all files Collapse all files

115
src/video/sdl_v.cpp
View File

@@ -23,8 +23,6 @@
#include "../window_func.h"
#include "sdl_v.h"
#include <SDL.h>
#include <mutex>
#include <condition_variable>
#include "../safeguards.h"
@@ -34,14 +32,6 @@ static SDL_Surface *_sdl_surface;
static SDL_Surface *_sdl_realscreen;
static bool _all_modes;
/** Whether the drawing is/may be done in a separate thread. */
static bool _draw_threaded;
/** Mutex to keep the access to the shared memory controlled. */
static std::recursive_mutex *_draw_mutex = nullptr;
/** Signal to draw the next frame. */
static std::condition_variable_any *_draw_signal = nullptr;
/** Should we keep continue drawing? */
static volatile bool _draw_continue;
static Palette _local_palette;
#define MAX_DIRTY_RECTS 100
@@ -174,27 +164,6 @@ void VideoDriver_SDL::Paint()
}
}
void VideoDriver_SDL::PaintThread()
{
/* First tell the main thread we're started */
std::unique_lock<std::recursive_mutex> lock(*_draw_mutex);
_draw_signal->notify_one();
/* Now wait for the first thing to draw! */
_draw_signal->wait(*_draw_mutex);
while (_draw_continue) {
/* Then just draw and wait till we stop */
this->Paint();
_draw_signal->wait(lock);
}
}
/* static */ void VideoDriver_SDL::PaintThreadThunk(VideoDriver_SDL *drv)
{
drv->PaintThread();
}
static const Dimension _default_resolutions[] = {
{ 640, 480},
{ 800, 600},
@@ -630,8 +599,6 @@ const char *VideoDriver_SDL::Start(const StringList &parm)
MarkWholeScreenDirty();
SetupKeyboard();
_draw_threaded = !GetDriverParamBool(parm, "no_threads") && !GetDriverParamBool(parm, "no_thread");
return nullptr;
}
@@ -680,80 +647,21 @@ void VideoDriver_SDL::InputLoop()
void VideoDriver_SDL::MainLoop()
{
std::thread draw_thread;
if (_draw_threaded) {
/* Initialise the mutex first, because that's the thing we *need*
* directly in the newly created thread. */
_draw_mutex = new std::recursive_mutex();
if (_draw_mutex == nullptr) {
_draw_threaded = false;
} else {
this->draw_lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
_draw_signal = new std::condition_variable_any();
_draw_continue = true;
_draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &VideoDriver_SDL::PaintThreadThunk, this);
/* Free the mutex if we won't be able to use it. */
if (!_draw_threaded) {
this->draw_lock.unlock();
this->draw_lock.release();
delete _draw_mutex;
delete _draw_signal;
_draw_mutex = nullptr;
_draw_signal = nullptr;
} else {
/* Wait till the draw mutex has started itself. */
_draw_signal->wait(*_draw_mutex);
}
}
}
DEBUG(driver, 1, "SDL: using %sthreads", _draw_threaded ? "" : "no ");
for (;;) {
if (_exit_game) break;
if (this->Tick()) {
if (_draw_mutex != nullptr && !HasModalProgress()) {
_draw_signal->notify_one();
} else {
this->Paint();
}
}
this->Tick();
this->SleepTillNextTick();
}
if (_draw_mutex != nullptr) {
_draw_continue = false;
/* Sending signal if there is no thread blocked
* is very valid and results in noop */
_draw_signal->notify_one();
if (this->draw_lock.owns_lock()) this->draw_lock.unlock();
this->draw_lock.release();
draw_thread.join();
delete _draw_mutex;
delete _draw_signal;
_draw_mutex = nullptr;
_draw_signal = nullptr;
}
}
bool VideoDriver_SDL::ChangeResolution(int w, int h)
{
std::unique_lock<std::recursive_mutex> lock;
if (_draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
return CreateMainSurface(w, h);
}
bool VideoDriver_SDL::ToggleFullscreen(bool fullscreen)
{
std::unique_lock<std::recursive_mutex> lock;
if (_draw_mutex != nullptr) lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
_fullscreen = fullscreen;
GetVideoModes(); // get the list of available video modes
bool ret = !_resolutions.empty() && CreateMainSurface(_cur_resolution.width, _cur_resolution.height);
@@ -772,25 +680,4 @@ bool VideoDriver_SDL::AfterBlitterChange()
return CreateMainSurface(_screen.width, _screen.height);
}
void VideoDriver_SDL::AcquireBlitterLock()
{
if (_draw_mutex != nullptr) _draw_mutex->lock();
}
void VideoDriver_SDL::ReleaseBlitterLock()
{
if (_draw_mutex != nullptr) _draw_mutex->unlock();
}
bool VideoDriver_SDL::LockVideoBuffer()
{
if (_draw_threaded) this->draw_lock.lock();
return true;
}
void VideoDriver_SDL::UnlockVideoBuffer()
{
if (_draw_threaded) this->draw_lock.unlock();
}
#endif /* WITH_SDL */