Fabric: SurfaceTelemetry now contains/records recent transaction telemetry points

Summary:
Now SurfaceTelemetry records the last 16 full transaction telemetries. We will use it info to report to our trackers.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: mdvacca

Differential Revision: D22887633

fbshipit-source-id: 0d88adff757e4bc5a701b51d4d06d85e1f51f10f

ReactCommon/react/renderer/mounting/SurfaceTelemetry.cpp

@@ -7,6 +7,8 @@
 
 #include "SurfaceTelemetry.h"
 
+#include <algorithm>
+
 namespace facebook {
 namespace react {
 
@@ -20,6 +22,13 @@ void SurfaceTelemetry::incorporate(
 
   numberOfTransactions_++;
   numberOfMutations_ += numberOfMutations;
+
+  while (recentCommitTelemetries_.size() >=
+         kMaxNumberOfRecordedCommitTelemetries) {
+    recentCommitTelemetries_.erase(recentCommitTelemetries_.begin());
+  }
+
+  recentCommitTelemetries_.push_back(telemetry);
 }
 
 TelemetryDuration SurfaceTelemetry::getLayoutTime() const {
@@ -46,5 +55,16 @@ int SurfaceTelemetry::getNumberOfMutations() const {
   return numberOfMutations_;
 }
 
+std::vector<MountingTelemetry> SurfaceTelemetry::getRecentCommitTelemetries()
+    const {
+  auto result = std::vector<MountingTelemetry>{};
+  result.reserve(recentCommitTelemetries_.size());
+  std::copy(
+      recentCommitTelemetries_.begin(),
+      recentCommitTelemetries_.end(),
+      std::back_inserter(result));
+  return result;
+}
+
 } // namespace react
 } // namespace facebook

ReactCommon/react/renderer/mounting/SurfaceTelemetry.h

@@ -7,6 +7,9 @@
 
 #pragma once
 
+#include <better/small_vector.h>
+#include <vector>
+
 #include <react/renderer/mounting/MountingTelemetry.h>
 #include <react/utils/Telemetry.h>
 
@@ -19,6 +22,8 @@ namespace react {
  */
 class SurfaceTelemetry final {
  public:
+  constexpr static size_t kMaxNumberOfRecordedCommitTelemetries = 16;
+
   /*
    * Metrics
    */
@@ -30,6 +35,8 @@ class SurfaceTelemetry final {
   int getNumberOfTransactions() const;
   int getNumberOfMutations() const;
 
+  std::vector<MountingTelemetry> getRecentCommitTelemetries() const;
+
   /*
    * Incorporate data from given transaction telemetry into aggregated data
    * for the Surface.
@@ -44,6 +51,9 @@ class SurfaceTelemetry final {
 
   int numberOfTransactions_{};
   int numberOfMutations_{};
+
+  better::small_vector<MountingTelemetry, kMaxNumberOfRecordedCommitTelemetries>
+      recentCommitTelemetries_{};
 };
 
 } // namespace react