[client] reworked frame timing waits for better responsiveness

client/src/main.c

@@ -71,8 +71,6 @@ static LGThread *t_cursor  = NULL;
 static LGThread *t_frame   = NULL;
 static SDL_Cursor *cursor  = NULL;
 
-static atomic_uint a_framesPending = 0;
-
 struct AppState state;
 
 // this structure is initialized in config.c
@@ -163,19 +161,13 @@ static int renderThread(void * unused)
   /* signal to other threads that the renderer is ready */
   lgSignalEvent(e_startup);
 
-  int resyncCheck = 0;
   struct timespec time;
-  clock_gettime(CLOCK_REALTIME, &time);
-
   while(state.state != APP_STATE_SHUTDOWN)
   {
     if (state.frameTime > 0)
     {
-      if (++resyncCheck == 100)
+      lgWaitEventAbs(e_frame, &time);
-      {
+      clock_gettime(CLOCK_MONOTONIC, &time);
-        resyncCheck = 0;
-        clock_gettime(CLOCK_REALTIME, &time);
-      }
       tsAdd(&time, state.frameTime);
     }
 
@@ -198,11 +190,16 @@ static int renderThread(void * unused)
 
       if (state.renderTime > 1e9)
       {
-        const float avgUPS = 1000.0f / (((float)state.renderTime / atomic_load_explicit(&state.frameCount, memory_order_acquire)) / 1e6f);
+        const float avgUPS = 1000.0f / (((float)state.renderTime /
-        const float avgFPS = 1000.0f / (((float)state.renderTime / state.renderCount) / 1e6f);
+          atomic_exchange_explicit(&state.frameCount, 0, memory_order_acquire)) /
+          1e6f);
+
+        const float avgFPS = 1000.0f / (((float)state.renderTime /
+          state.renderCount) /
+          1e6f);
+
         state.lgr->update_fps(state.lgrData, avgUPS, avgFPS);
 
-        atomic_store_explicit(&state.frameCount, 0, memory_order_release);
         state.renderTime  = 0;
         state.renderCount = 0;
       }
@@ -217,28 +214,6 @@ static int renderThread(void * unused)
       );
       state.resizeDone = true;
     }
-
-    if (state.frameTime > 0)
-    {
-      /* if there are frames pending already, don't wait on the event */
-      if (atomic_load_explicit(&a_framesPending, memory_order_acquire) > 0)
-        if (atomic_fetch_sub_explicit(&a_framesPending, 1, memory_order_release) > 1)
-          continue;
-
-      if (lgWaitEventAbs(e_frame, &time) && state.frameTime > 0)
-      {
-        /* only resync the timer if we got an early frame */
-        struct timespec now, diff;
-        clock_gettime(CLOCK_REALTIME, &now);
-        tsDiff(&diff, &time, &now);
-        if (diff.tv_sec == 0 && diff.tv_nsec < state.frameTime)
-        {
-          resyncCheck = 0;
-          memcpy(&time, &now, sizeof(struct timespec));
-          tsAdd(&time, state.frameTime);
-        }
-      }
-    }
   }
 
   state.state = APP_STATE_SHUTDOWN;
@@ -517,7 +492,6 @@ static int frameThread(void * unused)
     }
 
     atomic_fetch_add_explicit(&state.frameCount, 1, memory_order_relaxed);
-    if (atomic_fetch_add_explicit(&a_framesPending, 1, memory_order_relaxed) == 0)
     lgSignalEvent(e_frame);
 
     lgmpClientMessageDone(queue);
@@ -1425,8 +1399,8 @@ static int lg_run()
 
   if (params.fpsMin == -1)
   {
-      // minimum 60fps to keep interactivity decent
+    // default 30 fps
-      state.frameTime = 1000000000ULL / 60ULL;
+    state.frameTime = 1000000000ULL / 30ULL;
   }
   else
   {

common/src/platform/linux/event.c

@@ -32,7 +32,7 @@ struct LGEvent
 {
   pthread_mutex_t mutex;
   pthread_cond_t  cond;
-  uint32_t        flag;
+  atomic_uint     count;
   bool            autoReset;
 };
 
@@ -52,7 +52,18 @@ LGEvent * lgCreateEvent(bool autoReset, unsigned int msSpinTime)
     return NULL;
   }
 
-  if (pthread_cond_init(&handle->cond, NULL) != 0)
+  pthread_condattr_t cattr;
+  pthread_condattr_init(&cattr);
+
+  if (pthread_condattr_setclock(&cattr, CLOCK_MONOTONIC) != 0)
+  {
+    DEBUG_ERROR("Failed to set the condition clock to realtime");
+    pthread_mutex_destroy(&handle->mutex);
+    free(handle);
+    return NULL;
+  }
+
+  if (pthread_cond_init(&handle->cond, &cattr) != 0)
   {
     pthread_mutex_destroy(&handle->mutex);
     free(handle);
@@ -76,16 +87,17 @@ bool lgWaitEventAbs(LGEvent * handle, struct timespec * ts)
 {
   assert(handle);
 
+  bool ret = true;
+  int  res;
+
+  while(ret && atomic_load(&handle->count) == 0)
+  {
     if (pthread_mutex_lock(&handle->mutex) != 0)
     {
       DEBUG_ERROR("Failed to lock the mutex");
       return false;
     }
 
-  bool ret = true;
-  int  res;
-  while(ret && !atomic_load(&handle->flag))
-  {
     if (!ts)
     {
       if ((res = pthread_cond_wait(&handle->cond, &handle->mutex)) != 0)
@@ -111,16 +123,16 @@ bool lgWaitEventAbs(LGEvent * handle, struct timespec * ts)
           break;
       }
     }
-  }
-
-  if (handle->autoReset)
-    atomic_store(&handle->flag, 0);
 
     if (pthread_mutex_unlock(&handle->mutex) != 0)
     {
       DEBUG_ERROR("Failed to unlock the mutex");
       return false;
     }
+  }
+
+  if (ret && handle->autoReset)
+    atomic_fetch_sub(&handle->count, 1);
 
   return ret;
 }
@@ -131,11 +143,11 @@ bool lgWaitEventNS(LGEvent * handle, unsigned int timeout)
     return lgWaitEventAbs(handle, NULL);
 
   struct timespec ts;
-  clock_gettime(CLOCK_REALTIME, &ts);
+  clock_gettime(CLOCK_MONOTONIC, &ts);
   uint64_t nsec = ts.tv_nsec + timeout;
-  if(nsec > 1e9)
+  if(nsec > 1000000000UL)
   {
-    ts.tv_nsec = nsec - 1e9;
+    ts.tv_nsec = nsec - 1000000000UL;
     ++ts.tv_sec;
   }
   else
@@ -149,26 +161,18 @@ bool lgWaitEvent(LGEvent * handle, unsigned int timeout)
   if (timeout == TIMEOUT_INFINITE)
     return lgWaitEventAbs(handle, NULL);
 
-  return lgWaitEventNS(handle, timeout * 1000000);
+  return lgWaitEventNS(handle, timeout * 1000000U);
 }
 
 bool lgSignalEvent(LGEvent * handle)
 {
   assert(handle);
 
-  if (pthread_mutex_lock(&handle->mutex) != 0)
+  const bool signalled = atomic_fetch_add_explicit(&handle->count, 1,
-  {
+      memory_order_acquire) > 0;
-    DEBUG_ERROR("Failed to lock the mutex");
-    return false;
-  }
 
-  atomic_store(&handle->flag, 1);
+  if (signalled)
-
+    return true;
-  if (pthread_mutex_unlock(&handle->mutex) != 0)
-  {
-    DEBUG_ERROR("Failed to unlock the mutex");
-    return false;
-  }
 
   if (pthread_cond_broadcast(&handle->cond) != 0)
   {
@@ -182,20 +186,6 @@ bool lgSignalEvent(LGEvent * handle)
 bool lgResetEvent(LGEvent * handle)
 {
   assert(handle);
-
+  atomic_store(&handle->count, 0);
-  if (pthread_mutex_lock(&handle->mutex) != 0)
-  {
-    DEBUG_ERROR("Failed to lock the mutex");
-    return false;
-  }
-
-  atomic_store(&handle->flag, 0);
-
-  if (pthread_mutex_unlock(&handle->mutex) != 0)
-  {
-    DEBUG_ERROR("Failed to unlock the mutex");
-    return false;
-  }
-
   return true;
 }