From 0d7a0dc9976b179fab8ee1b77c9b9faf85f7d828 Mon Sep 17 00:00:00 2001
From: Luna Wei <luwe@fb.com>
Date: Mon, 13 May 2019 10:57:33 -0700
Subject: [PATCH] Add log to view that is being dropped

Summary:
We are getting errors where views are being dropped twice.
This is following from logic that viewManagers are only removed from `mTagsToViewManagers` from `dropView`.

This log will hopefully identify if we are getting improper operations because we shouldn't be re-using tags

Reviewed By: mdvacca

Differential Revision: D15152869

fbshipit-source-id: 914ee9c1772fa066adefde0753075ecba6377a0c
---
 .../react/config/ReactFeatureFlags.java        |  6 ++++++
 .../uimanager/NativeViewHierarchyManager.java  | 18 +++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java b/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
index 1171fa909c..94ae2364c6 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
@@ -37,4 +37,10 @@ public class ReactFeatureFlags {
    * C++ CatalystInstanceImpl
    */
   public static boolean useTurboModules = false;
+
+  /**
+   * Log tags of when a view deleted on the native side
+   * {@link com.facebook.react.uimanager.NativeViewHierarchyManager dropView}
+   */
+  public static boolean logDroppedViews = false;
 }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
index cec15412ed..724dd8e81d 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
@@ -28,11 +28,13 @@ import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.bridge.SoftAssertions;
 import com.facebook.react.bridge.UiThreadUtil;
+import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.touch.JSResponderHandler;
 import com.facebook.react.uimanager.layoutanimation.LayoutAnimationController;
 import com.facebook.react.uimanager.layoutanimation.LayoutAnimationListener;
 import com.facebook.systrace.Systrace;
 import com.facebook.systrace.SystraceMessage;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 import javax.annotation.Nullable;
@@ -73,9 +75,11 @@ public class NativeViewHierarchyManager {
   private final RootViewManager mRootViewManager;
   private final LayoutAnimationController mLayoutAnimator = new LayoutAnimationController();
   private final Map<Integer, SparseIntArray> mTagsToPendingIndicesToDelete = new HashMap<>();
+  private final int[] mDroppedViewArray = new int[100];
 
   private boolean mLayoutAnimationEnabled;
   private PopupMenu mPopupMenu;
+  private int mDroppedViewIndex = 0;
 
   public NativeViewHierarchyManager(ViewManagerRegistry viewManagers) {
     this(viewManagers, new RootViewManager());
@@ -101,7 +105,11 @@ public class NativeViewHierarchyManager {
   public synchronized final ViewManager resolveViewManager(int tag) {
     ViewManager viewManager = mTagsToViewManagers.get(tag);
     if (viewManager == null) {
-      throw new IllegalViewOperationException("ViewManager for tag " + tag + " could not be found");
+      boolean alreadyDropped = Arrays.asList(mDroppedViewArray).contains(tag);
+      throw new IllegalViewOperationException("ViewManager for tag "
+          + tag + " could not be found.\n View already dropped? "
+          + alreadyDropped + ".\nLast index "+ mDroppedViewIndex + " in last 100 views"
+          + mDroppedViewArray.toString());
     }
     return viewManager;
   }
@@ -587,6 +595,11 @@ public class NativeViewHierarchyManager {
     view.setId(tag);
   }
 
+  private void cacheDroppedTag(int tag) {
+    mDroppedViewArray[mDroppedViewIndex] = tag;
+    mDroppedViewIndex = (mDroppedViewIndex + 1) % 100;
+  }
+
   /**
    * Releases all references to given native View.
    */
@@ -596,6 +609,9 @@ public class NativeViewHierarchyManager {
       // Ignore this drop operation when view is null.
       return;
     }
+    if (ReactFeatureFlags.logDroppedViews) {
+      cacheDroppedTag(view.getId());
+    }
     if (mTagsToViewManagers.get(view.getId()) == null) {
       // This view has already been dropped (likely due to a threading issue caused by async js
       // execution). Ignore this drop operation.