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  1. #include <iostream>
  2. #include <thread>
  3. #include <chrono>
  4. #include <atomic>
  5. #include <functional>
  6. #include <mutex>
  7. #include <condition_variable>
  8.  
  9. using namespace std;
  10.  
  11. bool isMultiThreaded = true;
  12.  
  13. struct RenderThread
  14. {
  15.     RenderThread()
  16.     {
  17.         end = false;
  18.         drawing = false;
  19.         readyToDraw = false;
  20.     }
  21.  
  22.     void Run()
  23.     {
  24.         while (!end)
  25.         {
  26.             DoJob();
  27.         }
  28.     }
  29.  
  30.     void DoJob()
  31.     {
  32.         unique_lock<mutex> lk(renderReadyMutex);
  33.         renderReady.wait(lk, [this](){ return readyToDraw; });
  34.         drawing = true;
  35.  
  36.         // RENDER DATA
  37.         this_thread::sleep_for(chrono::milliseconds(15)); // simulated render time
  38.         cout << "frame " << count << ": " << frame << endl;
  39.         ++count;
  40.  
  41.         drawing = false;
  42.         readyToDraw = false;
  43.  
  44.         lk.unlock();
  45.         renderReady.notify_one();
  46.     }
  47.  
  48.     atomic<bool> end;
  49.  
  50.     mutex renderReadyMutex;
  51.     condition_variable renderReady;
  52.     //mutex frame_mutex;
  53.     int frame = -10;
  54.     int count = 0;
  55.  
  56.     bool readyToDraw;
  57.     bool drawing;
  58. };
  59.  
  60. struct UpdateThread
  61. {
  62.     UpdateThread(RenderThread& rt)
  63.         : m_rt(rt)
  64.     {}
  65.  
  66.     void Run()
  67.     {
  68.         this_thread::sleep_for(chrono::milliseconds(500));
  69.  
  70.         for (int i = 0; i < 20; ++i)
  71.         {
  72.             // DO GAME UPDATE
  73.  
  74.             // when this is uncommented everything is fine
  75.             // this_thread::sleep_for(chrono::milliseconds(10)); // simulated update time
  76.  
  77.             // PREPARE RENDER THREAD
  78.             unique_lock<mutex> lk(m_rt.renderReadyMutex);
  79.             m_rt.renderReady.wait(lk, [this](){ return !m_rt.drawing; });
  80.  
  81.             m_rt.readyToDraw = true;
  82.  
  83.             // SUPPLY RENDER THREAD WITH DATA TO RENDER
  84.             m_rt.frame = i;
  85.  
  86.             lk.unlock();
  87.             m_rt.renderReady.notify_one();
  88.  
  89.             if (!isMultiThreaded)
  90.                 m_rt.DoJob();
  91.         }        
  92.  
  93.         m_rt.end = true;
  94.     }
  95.  
  96.     RenderThread& m_rt;
  97. };
  98.  
  99. int main()
  100. {
  101.     auto start = chrono::high_resolution_clock::now();
  102.  
  103.     RenderThread rt;
  104.     UpdateThread u(rt);
  105.  
  106.     thread* rendering = nullptr;
  107.     if (isMultiThreaded)
  108.         rendering = new thread(bind(&RenderThread::Run, &rt));
  109.  
  110.     u.Run();
  111.  
  112.     if (rendering)
  113.         rendering->join();
  114.  
  115.     auto duration = chrono::high_resolution_clock::now() - start;
  116.     cout << "Duration: " << double(chrono::duration_cast<chrono::microseconds>(duration).count())/1000 << endl;
  117.  
  118.  
  119.     return 0;
  120. }
Success #stdin #stdout 0s 11664KB
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Standard input is empty
stdout
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frame 0: 19
Duration: 515.451
https://ideone.com/99qJ8e
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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