1 files changed, 124 insertions, 0 deletions
diff --git a/dom/base/ScrollingMetrics.cpp b/dom/base/ScrollingMetrics.cpp
new file mode 100644
index 0000000000..78dc607023
--- /dev/null
+++ b/dom/base/ScrollingMetrics.cpp
@@ -0,0 +1,124 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ScrollingMetrics.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/StaticPrefs_browser.h"
+
+namespace mozilla {
+
+static TimeStamp gScrollingStartTime;
+static TimeStamp gScrollingEndTime;
+static uint32_t gScrollDistanceCSSPixels = 0;
+static dom::InteractionData gScrollingInteraction = {};
+
+void ScrollingMetrics::OnScrollingInteractionEnded() {
+  // We are only interested in content process scrolling
+  if (XRE_IsParentProcess()) {
+    return;
+  }
+
+  if (!gScrollingStartTime.IsNull() && !gScrollingEndTime.IsNull()) {
+    gScrollingInteraction.mInteractionCount++;
+    gScrollingInteraction.mInteractionTimeInMilliseconds +=
+        static_cast<uint32_t>(
+            (gScrollingEndTime - gScrollingStartTime).ToMilliseconds());
+
+    gScrollingInteraction.mScrollingDistanceInPixels +=
+        gScrollDistanceCSSPixels;
+  }
+
+  gScrollDistanceCSSPixels = 0;
+  gScrollingStartTime = TimeStamp();
+  gScrollingEndTime = TimeStamp();
+}
+
+void ScrollingMetrics::OnScrollingInteraction(CSSCoord distanceScrolled) {
+  // We are only interested in content process scrolling
+  if (XRE_IsParentProcess()) {
+    return;
+  }
+
+  TimeStamp now = TimeStamp::Now();
+  if (gScrollingEndTime.IsNull()) {
+    gScrollingEndTime = now;
+  }
+
+  TimeDuration delay = now - gScrollingEndTime;
+
+  // Has it been too long since the last scroll input event to consider it part
+  // of the same interaction?
+  if (delay >
+      TimeDuration::FromMilliseconds(
+          StaticPrefs::browser_places_interactions_scrolling_timeout_ms())) {
+    OnScrollingInteractionEnded();
+  }
+
+  if (gScrollingStartTime.IsNull()) {
+    gScrollingStartTime = now;
+  }
+  gScrollingEndTime = now;
+  gScrollDistanceCSSPixels += static_cast<uint32_t>(distanceScrolled);
+}
+
+StaticAutoPtr<ScrollingMetrics> ScrollingMetrics::sSingleton;
+
+ScrollingMetrics* ScrollingMetrics::GetSingleton() {
+  if (!sSingleton) {
+    sSingleton = new ScrollingMetrics;
+  }
+
+  return sSingleton.get();
+}
+
+struct ScrollingMetricsCollector {
+  void AppendScrollingMetrics(const std::tuple<uint32_t, uint32_t>& aMetrics,
+                              dom::ContentParent* aParent) {
+    mTimeScrolledMS += std::get<0>(aMetrics);
+    mDistanceScrolledPixels += std::get<1>(aMetrics);
+  }
+
+  ~ScrollingMetricsCollector() {
+    mPromiseHolder.Resolve(
+        std::make_tuple(mTimeScrolledMS, mDistanceScrolledPixels), __func__);
+  }
+
+  uint32_t mTimeScrolledMS = 0;
+  uint32_t mDistanceScrolledPixels = 0;
+  MozPromiseHolder<ScrollingMetrics::ScrollingMetricsPromise> mPromiseHolder;
+};
+
+auto ScrollingMetrics::CollectScrollingMetricsInternal()
+    -> RefPtr<ScrollingMetrics::ScrollingMetricsPromise> {
+  std::shared_ptr<ScrollingMetricsCollector> collector =
+      std::make_shared<ScrollingMetricsCollector>();
+
+  nsTArray<dom::ContentParent*> contentParents;
+  dom::ContentParent::GetAll(contentParents);
+  for (dom::ContentParent* parent : contentParents) {
+    RefPtr<dom::ContentParent> parentRef = parent;
+    parent->SendCollectScrollingMetrics(
+        [collector, parentRef](const std::tuple<uint32_t, uint32_t>& aMetrics) {
+          collector->AppendScrollingMetrics(aMetrics, parentRef.get());
+        },
+        [](mozilla::ipc::ResponseRejectReason) {});
+  }
+
+  return collector->mPromiseHolder.Ensure(__func__);
+}
+
+std::tuple<uint32_t, uint32_t>
+ScrollingMetrics::CollectLocalScrollingMetricsInternal() {
+  OnScrollingInteractionEnded();
+
+  std::tuple<uint32_t, uint32_t> metrics =
+      std::make_tuple(gScrollingInteraction.mInteractionTimeInMilliseconds,
+                      gScrollingInteraction.mScrollingDistanceInPixels);
+  gScrollingInteraction = {};
+  return metrics;
+}
+
+}  // namespace mozilla