Pace all frames to the frame rate, at best effort

The pacer counted only its own frames, so the client's 30 came on top (60 gave
about 80), and it added no frames at all when the rate was out of reach. It now
asks for a window's next frame once the interval since its last frame began has
passed, and the client has had a third of a frame's time idle: all frames
within the rate, and as many as the client can draw when it can't reach it.

The engine's stats also break a frame's time down: sending to the renderer
process, bytes sent, buffer updates.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

adapter/engine.cpp

@@ -303,8 +303,10 @@ void Engine::endRendering()
         LARGE_INTEGER end, frequency;
         QueryPerformanceCounter(&end);
         QueryPerformanceFrequency(&frequency);
-        frame_pacer::frameDrawn(window_, static_cast<double>(end.QuadPart - frameStart_.QuadPart) /
-                                             static_cast<double>(frequency.QuadPart));
+        const double seconds =
+            static_cast<double>(end.QuadPart - frameStart_.QuadPart) / static_cast<double>(frequency.QuadPart);
+        frameSeconds_ += seconds;
+        frame_pacer::frameDrawn(window_, seconds);
     }
     ourTarget_ = nullptr;
     ++frames_;
@@ -315,14 +317,20 @@ void Engine::endRendering()
         const double seconds =
             static_cast<double>(ended.QuadPart - statsStart_.QuadPart) / static_cast<double>(frequency.QuadPart);
         statsStart_ = ended;
+        const Recorder::Counters sent = recorder_->takeCounters();
         if (statsLogged_ < 6 || frames_ % 3000 == 0) {
             ++statsLogged_;
-            log::info("engine: last 300 frames: {:.0f} per second; drawTriangles {} (and {} with buffers not ours), "
-                      "drawTrianglesFromMemory {} (and {} without indices), point sprites {}, lines {}, 2D projections {}",
-                      300 / seconds, stats_.triangles, stats_.foreignTriangles, stats_.indexed, stats_.unindexed,
-                      stats_.sprites, stats_.lines, stats_.flat);
+            log::info("engine: last 300 frames: {:.0f} per second; each {:.2f} ms beginRendering to endRendering, {:.2f} ms "
+                      "of it sending, {:.0f} KB sent, {:.1f} buffer updates ({:.0f} KB); drawTriangles {} (and {} with "
+                      "buffers not ours), drawTrianglesFromMemory {} (and {} without indices), point sprites {}, lines {}, "
+                      "2D projections {}",
+                      300 / seconds, frameSeconds_ * 1000 / 300, sent.sendSeconds * 1000 / 300,
+                      static_cast<double>(sent.bytes) / 1024 / 300, sent.bufferUpdates / 300.0,
+                      static_cast<double>(sent.bufferBytes) / 1024 / 300, stats_.triangles, stats_.foreignTriangles,
+                      stats_.indexed, stats_.unindexed, stats_.sprites, stats_.lines, stats_.flat);
         }
         stats_ = {};
+        frameSeconds_ = 0;
     }
 }