Track how much measure cache entries are used

Summary:
@public

Adds the maximum number of measure cache entries in use to the metrics for `YGMarkerLayout`

Reviewed By: SidharthGuglani

Differential Revision: D13844731

fbshipit-source-id: fa66dbf1b7a1799494f72ecc17dfaef04d0b56e4

tests/InstrumentationTest.cpp

@@ -110,7 +110,7 @@ TEST_F(MarkerTest, layout_marker_counts_single_node_layout) {
 
   ASSERT_EQ(
       markerCookie.end.markerData.layout,
-      (YGMarkerLayoutData{.layouts = 1, .measures = 0}));
+      (YGMarkerLayoutData{.layouts = 1, .measures = 0, .maxMeasureCache = 1}));
 }
 
 TEST_F(MarkerTest, layout_marker_counts_multi_node_layout) {
@@ -122,7 +122,7 @@ TEST_F(MarkerTest, layout_marker_counts_multi_node_layout) {
 
   ASSERT_EQ(
       markerCookie.end.markerData.layout,
-      (YGMarkerLayoutData{.layouts = 3, .measures = 4}));
+      (YGMarkerLayoutData{.layouts = 3, .measures = 4, .maxMeasureCache = 3}));
 }
 
 TEST_F(MarkerTest, layout_marker_counts_cache_hits_single_node_layout) {
@@ -152,10 +152,26 @@ TEST_F(MarkerTest, layout_marker_counts_cache_hits_multi_node_layout) {
       markerCookie.end.markerData.layout,
       (YGMarkerLayoutData{.layouts = 3,
                           .measures = 0,
+                          .maxMeasureCache = 5,
                           .cachedLayouts = 0,
                           .cachedMeasures = 4}));
 }
 
+TEST_F(MarkerTest, layout_marker_has_max_measure_cache) {
+  auto root = makeNode();
+  auto a = addChild(root);
+  auto b = addChild(root);
+  YGNodeStyleSetFlexBasis(a.get(), 10.0f);
+
+  for (auto s : {20, 30, 40}) {
+    calculateLayout(root, s, s);
+  }
+
+  ASSERT_EQ(
+      markerCookie.end.markerData.layout,
+      (YGMarkerLayoutData{.layouts = 3, .measures = 3, .maxMeasureCache = 7}));
+}
+
 void* MarkerTest::startMarker(
     YGMarker marker,
     YGNodeRef node,
@@ -211,6 +227,7 @@ decltype(MarkerTest::markerCookie) MarkerTest::markerCookie = {};
 
 bool operator==(const YGMarkerLayoutData& lhs, const YGMarkerLayoutData& rhs) {
   return lhs.layouts == rhs.layouts && lhs.measures == rhs.measures &&
+      lhs.maxMeasureCache == rhs.maxMeasureCache &&
       lhs.cachedLayouts == rhs.cachedLayouts &&
       lhs.cachedMeasures == rhs.cachedMeasures;
 }
@@ -218,6 +235,7 @@ bool operator==(const YGMarkerLayoutData& lhs, const YGMarkerLayoutData& rhs) {
 void PrintTo(const YGMarkerLayoutData data, std::ostream* os) {
   *os << "YGMarkerLayoutData{ layouts = " << data.layouts
       << ", measures = " << data.measures
+      << ", maxMeasureCache = " << data.maxMeasureCache
       << ", cachedLayouts = " << data.cachedLayouts
       << ", cachedMeasures = " << data.cachedMeasures << " }";
 }

yoga/YGMarker.h

@@ -20,6 +20,7 @@ typedef YG_ENUM_BEGIN(YGMarker){
 typedef struct {
   int layouts;
   int measures;
+  int maxMeasureCache;
   int cachedLayouts;
   int cachedMeasures;
 } YGMarkerLayoutData;

yoga/Yoga.cpp

@@ -3889,6 +3889,11 @@ bool YGLayoutNodeInternal(
     layout->lastOwnerDirection = ownerDirection;
 
     if (cachedResults == nullptr) {
+      if (layout->nextCachedMeasurementsIndex + 1 >
+          (uint32_t) layoutMarkerData.maxMeasureCache) {
+        layoutMarkerData.maxMeasureCache =
+            layout->nextCachedMeasurementsIndex + 1;
+      }
       if (layout->nextCachedMeasurementsIndex == YG_MAX_CACHED_RESULT_COUNT) {
         if (gPrintChanges) {
           YGLog(node, YGLogLevelVerbose, "Out of cache entries!\n");