Adds 4 CVals to track WebP usage and performance (#1020)

This PR adds tracking around AnimatedImage, which is currently only used
for WebP decoding.
We are adding 4 metrics
 - Total number of currently decoding WebP images
 - Cumulative total of frames decoded
 - Decoding underruns, when CPU bottleneck is hit
- Decoding overruns, when timing in decoding pipeline is trying to
decode too fast.

b/196887641
b/280381029
b/290130439
b/290060548

(cherry picked from commit d0684de)

cobalt/browser/web_module.cc

@@ -564,6 +564,7 @@ WebModule::Impl::Impl(web::Context* web_context, const ConstructionData& data)
       data.options.loader_thread_priority));
 
   animated_image_tracker_.reset(new loader::image::AnimatedImageTracker(
+      web_context_->name().c_str(),
       data.options.animated_image_decode_thread_priority));
 
   DCHECK_LE(0, data.options.image_cache_capacity);
@@ -1017,6 +1018,7 @@ void WebModule::Impl::ProcessOnRenderTreeRasterized(
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
   web_module_stat_tracker_->OnRenderTreeRasterized(produced_time,
                                                    rasterized_time);
+  animated_image_tracker_->OnRenderTreeRasterized();
   if (produced_time >= last_render_tree_produced_time_) {
     is_render_tree_rasterization_pending_ = false;
   }

cobalt/loader/image/animated_image_tracker.cc

@@ -15,7 +15,9 @@
 #include "cobalt/loader/image/animated_image_tracker.h"
 
 #include <algorithm>
+#include <utility>
 
+#include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
 #include "cobalt/base/polymorphic_downcast.h"
 
@@ -24,8 +26,22 @@ namespace loader {
 namespace image {
 
 AnimatedImageTracker::AnimatedImageTracker(
+    const char* name,
     base::ThreadPriority animated_image_decode_thread_priority)
-    : animated_image_decode_thread_("AnimatedImage") {
+    : animated_image_decode_thread_("AnimatedImage"),
+      name_(name),
+      count_animated_images_active(
+          base::StringPrintf("Count.%s.AnimatedImage.Active", name), 0,
+          "Total number of active animated image decoders."),
+      count_animated_frames_decoded(
+          base::StringPrintf("Count.%s.AnimatedImage.DecodedFrames", name), 0,
+          "Total number of decoded animated image frames."),
+      count_animated_frames_decoding_underrun(
+          base::StringPrintf("Count.%s.AnimatedImage.DecodingUnderruns", name),
+          0, "Number of underruns from decoding animated images"),
+      count_animated_frames_decoding_overrun(
+          base::StringPrintf("Count.%s.AnimatedImage.DecodingOverruns", name),
+          0, "Number of overruns from decoding animated images") {
   TRACE_EVENT0("cobalt::loader::image", "AnimatedImageTracker::RecordImage()");
   base::Thread::Options options(base::MessageLoop::TYPE_DEFAULT,
                                 0 /* default stack size */);
@@ -123,6 +139,17 @@ void AnimatedImageTracker::Reset() {
   playing_urls_.clear();
 }
 
+void AnimatedImageTracker::OnRenderTreeRasterized() {
+  count_animated_images_active = playing_urls_.size();
+  for (const auto& playing_url : playing_urls_) {
+    auto image = image_map_[playing_url.first].get();
+    auto stats = image->GetFrameDeltaStats();
+    count_animated_frames_decoded += stats.frames_decoded;
+    count_animated_frames_decoding_underrun += stats.frames_underrun;
+    count_animated_frames_decoding_overrun += stats.frames_overrun;
+  }
+}
+
 }  // namespace image
 }  // namespace loader
 }  // namespace cobalt

cobalt/loader/image/animated_image_tracker.h

@@ -20,6 +20,7 @@
 
 #include "base/containers/small_map.h"
 #include "base/threading/thread.h"
+#include "cobalt/base/c_val.h"
 #include "cobalt/base/unused.h"
 #include "cobalt/loader/image/image.h"
 #include "url/gurl.h"
@@ -33,7 +34,8 @@ namespace image {
 // playing status is updated hence decoding is turned on / off for it.
 class AnimatedImageTracker {
  public:
-  explicit AnimatedImageTracker(
+  AnimatedImageTracker(
+      const char* name,
       base::ThreadPriority animated_image_decode_thread_priority);
   ~AnimatedImageTracker();
 
@@ -54,6 +56,9 @@ class AnimatedImageTracker {
   // animations.
   void Reset();
 
+  // Called from WebModule to compute image animation related stats.
+  void OnRenderTreeRasterized();
+
  private:
   void OnDisplayStart(loader::image::AnimatedImage* image);
   void OnDisplayEnd(loader::image::AnimatedImage* image);
@@ -72,6 +77,15 @@ class AnimatedImageTracker {
   URLToIntMap current_url_counts_;
   URLSet playing_urls_;
 
+  // The name of the WebModule this AnimatedImage tracker belongs to, for CVals.
+  const std::string name_;
+
+  // Animated image counters
+  base::CVal<int, base::CValPublic> count_animated_images_active;
+  base::CVal<int, base::CValPublic> count_animated_frames_decoded;
+  base::CVal<int, base::CValPublic> count_animated_frames_decoding_underrun;
+  base::CVal<int, base::CValPublic> count_animated_frames_decoding_overrun;
+
   // Used to ensure that all AnimatedImageTracker methods are called on the
   // same thread (*not* |animated_image_decode_thread_|), the thread that we
   // were constructed on.

cobalt/loader/image/animated_webp_image.cc

@@ -148,6 +148,8 @@ void AnimatedWebPImage::PlayInternal() {
     return;
   }
   is_playing_ = true;
+  current_stats.frames_underrun = 0;
+  current_stats.frames_overrun = 0;
 
   if (received_first_frame_) {
     StartDecoding();
@@ -171,7 +173,8 @@ void AnimatedWebPImage::StopInternal() {
 void AnimatedWebPImage::StartDecoding() {
   TRACE_EVENT0("cobalt::loader::image", "AnimatedWebPImage::StartDecoding()");
   lock_.AssertAcquired();
-  current_frame_time_ = base::TimeTicks::Now();
+  decoding_start_time_ = current_frame_time_ = base::TimeTicks::Now();
+  current_stats.frames_decoded = 0;
   if (task_runner_->BelongsToCurrentThread()) {
     DecodeFrames();
   } else {
@@ -269,6 +272,7 @@ bool AnimatedWebPImage::DecodeOneFrame(int frame_index) {
       LOG(ERROR) << "Failed to decode WebP image frame.";
       return false;
     }
+    current_stats.frames_decoded++;
   }
 
   // Alpha blend the current frame on top of the buffer.
@@ -354,6 +358,7 @@ bool AnimatedWebPImage::AdvanceFrame() {
   // Always wait for a consumer to consume the previous frame before moving
   // forward with decoding the next frame.
   if (!frame_provider_->FrameConsumed()) {
+    current_stats.frames_overrun++;
     return false;
   }
 
@@ -386,6 +391,7 @@ bool AnimatedWebPImage::AdvanceFrame() {
   if (next_frame_time_ < current_time) {
     // Don't let the animation fall back for more than a frame.
     next_frame_time_ = current_time;
+    current_stats.frames_underrun++;
   }
 
   return true;
@@ -431,6 +437,25 @@ scoped_refptr<render_tree::Image> AnimatedWebPImage::GetFrameForDebugging(
   return target_canvas;
 }
 
+AnimatedImage::AnimatedImageDecodingStats
+AnimatedWebPImage::GetFrameDeltaStats() {
+  AnimatedImageDecodingStats result;
+  if (current_stats.frames_decoded >= last_stats.frames_decoded) {
+    result.frames_decoded =
+        current_stats.frames_decoded - last_stats.frames_decoded;
+    result.frames_underrun =
+        current_stats.frames_underrun - last_stats.frames_underrun;
+    result.frames_overrun =
+        current_stats.frames_overrun - last_stats.frames_overrun;
+  } else {
+    // There was a reset somewhere
+    // Simply return total, this discards any overflow data we might have had.
+    result = current_stats;
+  }
+  last_stats = current_stats;
+  return result;
+}
+
 }  // namespace image
 }  // namespace loader
 }  // namespace cobalt

cobalt/loader/image/animated_webp_image.h

@@ -66,6 +66,8 @@ class AnimatedWebPImage : public AnimatedImage {
   // Returns the render image of the frame for debugging
   scoped_refptr<render_tree::Image> GetFrameForDebugging(int target_frame);
 
+  AnimatedImageDecodingStats GetFrameDeltaStats() override;
+
  private:
   ~AnimatedWebPImage() override;
 
@@ -119,12 +121,17 @@ class AnimatedWebPImage : public AnimatedImage {
   base::CancelableClosure decode_closure_;
   base::TimeTicks current_frame_time_;
   base::Optional<base::TimeTicks> next_frame_time_;
+
   // The original encoded data.
   std::vector<uint8> data_buffer_;
   scoped_refptr<render_tree::Image> current_canvas_;
   scoped_refptr<FrameProvider> frame_provider_;
   base::Lock lock_;
 
+  base::TimeTicks decoding_start_time_;
+  AnimatedImageDecodingStats current_stats;
+  AnimatedImageDecodingStats last_stats;
+
   // Makes sure that the thread that sets the task_runner is always consistent.
   // This is the thread sending Play()/Stop() calls, and is not necessarily
   // the same thread that the task_runner itself is running on.

cobalt/loader/image/image.h

@@ -145,6 +145,16 @@ class AnimatedImage : public Image {
     image_node_builder->destination_rect = destination_rect;
     image_node_builder->local_transform = local_transform;
   }
+
+  // Frame counters for decoding.
+  struct AnimatedImageDecodingStats {
+    unsigned int frames_decoded = 0;
+    unsigned int frames_underrun = 0;
+    unsigned int frames_overrun = 0;
+  };
+
+  // Returns decoded frame stats since the last call, as a delta.
+  virtual AnimatedImageDecodingStats GetFrameDeltaStats() = 0;
 };
 
 }  // namespace image