Add frame time instrumentation to headless renderer

2 files changed, 17 insertions, 4 deletions

diff --git a/platform/default/include/mbgl/gfx/headless_frontend.hpp b/platform/default/include/mbgl/gfx/headless_frontend.hpp
index 33d3adea4f..b777cc7b7f 100644
--- a/platform/default/include/mbgl/gfx/headless_frontend.hpp
+++ b/platform/default/include/mbgl/gfx/headless_frontend.hpp
@@ -1,11 +1,12 @@
 #pragma once
 
+#include <mbgl/gfx/headless_backend.hpp>
 #include <mbgl/map/camera.hpp>
 #include <mbgl/renderer/renderer_frontend.hpp>
-#include <mbgl/gfx/headless_backend.hpp>
 #include <mbgl/util/async_task.hpp>
 #include <mbgl/util/optional.hpp>
 
+#include <atomic>
 #include <memory>
 
 namespace mbgl {
@@ -31,6 +32,7 @@ public:
     void update(std::shared_ptr<UpdateParameters>) override;
     void setObserver(RendererObserver&) override;
 
+    double getFrameTime() const;
     Size getSize() const;
     void setSize(Size);
 
@@ -54,6 +56,7 @@ private:
     Size size;
     float pixelRatio;
 
+    std::atomic<double> frameTime;
     std::unique_ptr<gfx::HeadlessBackend> backend;
     util::AsyncTask asyncInvalidate;
 
diff --git a/platform/default/src/mbgl/gfx/headless_frontend.cpp b/platform/default/src/mbgl/gfx/headless_frontend.cpp
index 7ec8a55ba7..b7156cc2b7 100644
--- a/platform/default/src/mbgl/gfx/headless_frontend.cpp
+++ b/platform/default/src/mbgl/gfx/headless_frontend.cpp
@@ -1,10 +1,11 @@
-#include <mbgl/gfx/headless_frontend.hpp>
 #include <mbgl/gfx/backend_scope.hpp>
+#include <mbgl/gfx/headless_frontend.hpp>
+#include <mbgl/map/map.hpp>
+#include <mbgl/map/transform_state.hpp>
 #include <mbgl/renderer/renderer.hpp>
 #include <mbgl/renderer/renderer_state.hpp>
 #include <mbgl/renderer/update_parameters.hpp>
-#include <mbgl/map/map.hpp>
-#include <mbgl/map/transform_state.hpp>
+#include <mbgl/util/monotonic_timer.hpp>
 #include <mbgl/util/run_loop.hpp>
 
 namespace mbgl {
@@ -22,12 +23,14 @@ HeadlessFrontend::HeadlessFrontend(Size size_,
                                    const optional<std::string> localFontFamily)
     : size(size_),
       pixelRatio(pixelRatio_),
+      frameTime(0),
       backend(gfx::HeadlessBackend::Create(
           {static_cast<uint32_t>(size.width * pixelRatio), static_cast<uint32_t>(size.height * pixelRatio)},
           swapBehavior,
           contextMode)),
       asyncInvalidate([this] {
           if (renderer && updateParameters) {
+              auto startTime = mbgl::util::MonotonicTimer::now();
               gfx::BackendScope guard{*getBackend()};
 
               // onStyleImageMissing might be called during a render. The user implemented method
@@ -36,6 +39,9 @@ HeadlessFrontend::HeadlessFrontend(Size size_,
               // still using them.
               auto updateParameters_ = updateParameters;
               renderer->render(*updateParameters_);
+
+              auto endTime = mbgl::util::MonotonicTimer::now();
+              frameTime = (endTime - startTime).count();
           }
       }),
       renderer(std::make_unique<Renderer>(*getBackend(), pixelRatio, localFontFamily)) {}
@@ -57,6 +63,10 @@ void HeadlessFrontend::setObserver(RendererObserver& observer_) {
     renderer->setObserver(&observer_);
 }
 
+double HeadlessFrontend::getFrameTime() const {
+    return frameTime;
+}
+
 Size HeadlessFrontend::getSize() const {
     return size;
 }