Ichthyostega
2a61def8a4
Since I want to segregate the code according to the domain, several methods must be provided to the video display to conduct a properly synchronised handover of video pixel data; by using `Glib::Dispatcher` as base class, all aspects of feed synchronisation can be packaged into a single connection interface, without having to share implementation details between the video display and player.
144 lines
3.3 KiB
C++
144 lines
3.3 KiB
C++
/*
|
||
demo-uring.cpp - async file IO with io_uring
|
||
|
||
Copyright (C)
|
||
2026, Hermann Vosseler <Ichthyostega@web.de>
|
||
|
||
This program is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU GPL version 2+ See the LICENSE file for details.
|
||
|
||
* ************************************************************************/
|
||
|
||
|
||
#include "commons.hpp"
|
||
#include "egl-display.hpp"
|
||
#include "gtk-uring-app.hpp"
|
||
|
||
#include <iostream>
|
||
#include <memory>
|
||
#include <thread>
|
||
#include <atomic>
|
||
|
||
using std::unique_ptr;
|
||
using std::make_unique;
|
||
|
||
//-----------------hard-coded-config--
|
||
const size_t RING_SIZ = 5;
|
||
|
||
const uint VIDEO_WIDTH = 320;
|
||
const uint VIDEO_HEIGHT = 240;
|
||
//-----------------hard-coded-config--
|
||
|
||
|
||
class UringVideoPlayer
|
||
: NonCopyable
|
||
{
|
||
using VideoDisplay = EglDisplay<uint8_t, VIDEO_WIDTH,VIDEO_HEIGHT>;
|
||
using Buffer = VideoDisplay::Buffer;
|
||
|
||
enum BuffState { FREE, READ, SHOW };
|
||
using AtomicBuffState = std::atomic<BuffState>;
|
||
|
||
using BufferAlloc = unique_ptr<Buffer[]>;
|
||
using BuffStateAlloc = unique_ptr<AtomicBuffState[]>;
|
||
|
||
/**
|
||
* Connector to the VideoDisplay for dispatching video data.
|
||
* @note inherits from Glib::Dispatcher -> signal frame readiness
|
||
* @remark the callback functions allow the VideoDisplay to interact
|
||
* with the buffer data and state in a threadsafe manner
|
||
*/
|
||
class BufferDispatcher
|
||
: public VideoDisplay::PixelFeed
|
||
{
|
||
Buffer* retrieveFrame() override;
|
||
void completedFrame() override;
|
||
|
||
UringVideoPlayer& player_;
|
||
public:
|
||
BufferDispatcher (UringVideoPlayer& player)
|
||
: player_{player}
|
||
{ }
|
||
};
|
||
|
||
size_t nextRead_{0};
|
||
size_t nextShow_{0};
|
||
BufferAlloc buffer_{};
|
||
BuffStateAlloc buffState_{};
|
||
std::atomic_bool playing_{false};
|
||
BufferDispatcher dispatchFrame_;
|
||
VideoDisplay videoDisplayer_;
|
||
std::thread proactorThread_;
|
||
|
||
public:
|
||
UringVideoPlayer (Gtk::Window& appWindow)
|
||
: dispatchFrame_{*this}
|
||
, videoDisplayer_{appWindow, dispatchFrame_}
|
||
, proactorThread_{[this]{ playVideo(); }}
|
||
{ }
|
||
|
||
void terminate();
|
||
|
||
private:
|
||
void playVideo();
|
||
};
|
||
|
||
|
||
/**
|
||
* Logic of the »Proactor Thread«:
|
||
* - maintain the working buffers
|
||
* - open the raw video file to retrieve data
|
||
* - establish an IO_URING connection for reading
|
||
* - periodic processing to fill and hand-off buffers
|
||
*/
|
||
void
|
||
UringVideoPlayer::playVideo()
|
||
{
|
||
buffer_ = make_unique<Buffer[]> (RING_SIZ);
|
||
buffState_ = make_unique<AtomicBuffState[]> (RING_SIZ);
|
||
// initialise URing
|
||
// ++ proactor-loop ++
|
||
}
|
||
|
||
|
||
UringVideoPlayer::Buffer*
|
||
UringVideoPlayer::BufferDispatcher::retrieveFrame()
|
||
{
|
||
///////OOO threadsafe hand-over of current frame data
|
||
}
|
||
|
||
|
||
void
|
||
UringVideoPlayer::BufferDispatcher::completedFrame()
|
||
{
|
||
///////OOO mark end of buffer access
|
||
}
|
||
|
||
|
||
void
|
||
UringVideoPlayer::terminate()
|
||
{
|
||
playing_.store (false, std::memory_order_release);
|
||
proactorThread_.join();
|
||
videoDisplayer_.cleanUp();
|
||
}
|
||
|
||
|
||
|
||
unique_ptr<UringVideoPlayer>
|
||
launchPlayer (Gtk::Window& appWindow)
|
||
{
|
||
appWindow.resize (VIDEO_WIDTH, VIDEO_HEIGHT);
|
||
return std::make_unique<UringVideoPlayer> (appWindow);
|
||
}
|
||
|
||
|
||
|
||
int
|
||
main (int, const char*[])
|
||
{
|
||
return GtkUringApp<UringVideoPlayer>{"io-uring-demo"}
|
||
.onClick (launchPlayer)
|
||
.onClose ([](auto& player){ player.terminate();})
|
||
.run();
|
||
}
|