Refactor caching of Spannable objects instide TextLayoutManager

Summary:
This diff optimizes the caching of Spannable objects managed by the TextLayoutManager class.
Previously, these objects were cached using unsing a String representation of the RedableMap (creating this string adds a non trivial cost), this diff improves the caching performance relying on the equals / hashcode methods of the ReadableNativeMap class

I created a MC just to have a killswitch

Motivation: I was analysing another bug and I found this non performant code

changelog: [internal] internal

Reviewed By: shergin

Differential Revision: D23429365

fbshipit-source-id: 59e5ad0b1b95da992ac393aecfe029da68a8df97

ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java

@@ -71,4 +71,7 @@ public class ReactFeatureFlags {
 
   /** Use experimental SetState retry mechanism in view? */
   public static boolean enableExperimentalStateUpdateRetry = false;
+
+  /** Enable caching of Spannable objects using equality of ReadableNativeMaps */
+  public static boolean enableSpannableCacheByReadableNativeMapEquality = true;
 }

ReactAndroid/src/main/java/com/facebook/react/views/text/BUCK

@@ -22,6 +22,7 @@ rn_android_library(
         react_native_dep("third-party/java/jsr-305:jsr-305"),
         react_native_target("java/com/facebook/react/bridge:bridge"),
         react_native_target("java/com/facebook/react/common:common"),
+        react_native_target("java/com/facebook/react/config:config"),
         react_native_target("java/com/facebook/react/module/annotations:annotations"),
         react_native_target("java/com/facebook/react/uimanager:uimanager"),
         react_native_target("java/com/facebook/react/uimanager/annotations:annotations"),

ReactAndroid/src/main/java/com/facebook/react/views/text/TextLayoutManager.java

@@ -26,6 +26,8 @@
 import com.facebook.common.logging.FLog;
 import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.ReadableNativeMap;
+import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.ReactStylesDiffMap;
 import com.facebook.react.uimanager.ViewProps;
@@ -61,6 +63,8 @@ public class TextLayoutManager {
   private static final String MAXIMUM_NUMBER_OF_LINES_KEY = "maximumNumberOfLines";
   private static final LruCache<String, Spannable> sSpannableCache =
       new LruCache<>(spannableCacheSize);
+  private static final LruCache<ReadableNativeMap, Spannable> sSpannableCacheV2 =
+      new LruCache<>(spannableCacheSize);
   private static final ConcurrentHashMap<Integer, Spannable> sTagToSpannableCache =
       new ConcurrentHashMap<>();
 
@@ -179,20 +183,40 @@ public static Spannable getOrCreateSpannableForText(
       @Nullable ReactTextViewManagerCallback reactTextViewManagerCallback) {
 
     Spannable preparedSpannableText;
-    String attributedStringPayload = attributedString.toString();
-    synchronized (sSpannableCacheLock) {
-      preparedSpannableText = sSpannableCache.get(attributedStringPayload);
-      // TODO: T31905686 implement proper equality of attributedStrings
-      if (preparedSpannableText != null) {
-        return preparedSpannableText;
+    String attributedStringPayload = "";
+
+    boolean cacheByReadableNativeMap =
+        ReactFeatureFlags.enableSpannableCacheByReadableNativeMapEquality;
+    // TODO: T74600554 Cleanup this experiment once positive impact is confirmed in production
+    if (cacheByReadableNativeMap) {
+      synchronized (sSpannableCacheLock) {
+        preparedSpannableText = sSpannableCacheV2.get((ReadableNativeMap) attributedString);
+        if (preparedSpannableText != null) {
+          return preparedSpannableText;
+        }
+      }
+    } else {
+      attributedStringPayload = attributedString.toString();
+      synchronized (sSpannableCacheLock) {
+        preparedSpannableText = sSpannableCache.get(attributedStringPayload);
+        if (preparedSpannableText != null) {
+          return preparedSpannableText;
+        }
       }
     }
 
     preparedSpannableText =
         createSpannableFromAttributedString(
             context, attributedString, reactTextViewManagerCallback);
-    synchronized (sSpannableCacheLock) {
-      sSpannableCache.put(attributedStringPayload, preparedSpannableText);
+
+    if (cacheByReadableNativeMap) {
+      synchronized (sSpannableCacheLock) {
+        sSpannableCacheV2.put((ReadableNativeMap) attributedString, preparedSpannableText);
+      }
+    } else {
+      synchronized (sSpannableCacheLock) {
+        sSpannableCache.put(attributedStringPayload, preparedSpannableText);
+      }
     }
     return preparedSpannableText;
   }