From 9bc2f6fec505d945c94731c1000eac92a4cda8bd Mon Sep 17 00:00:00 2001
From: Luke De Feo <lukedefeo@fb.com>
Date: Thu, 22 Sep 2022 04:26:18 -0700
Subject: [PATCH] Remove node Id from descriptor

Summary: It was always the system hash code and in many places it was inconvient to get the descriptor to just end up calling the same function

Reviewed By: lblasa

Differential Revision: D39700215

fbshipit-source-id: b1439d56cd8f39ba8735f933662ad79b87ffbdbe
---
 .../plugins/uidebugger/litho/LithoDescriptors.kt  |  3 ---
 .../plugins/uidebugger/litho/LithoObserver.kt     |  3 +++
 .../plugins/uidebugger/UIDebuggerFlipperPlugin.kt |  4 ++--
 .../uidebugger/descriptors/ActivityDescriptor.kt  |  4 ----
 .../descriptors/ApplicationRefDescriptor.kt       |  4 ----
 .../uidebugger/descriptors/ButtonDescriptor.kt    |  4 ----
 .../uidebugger/descriptors/ChainedDescriptor.kt   | 10 ----------
 .../descriptors/FragmentFrameworkDescriptor.kt    |  4 ----
 .../descriptors/FragmentSupportDescriptor.kt      |  4 ----
 .../uidebugger/descriptors/NodeDescriptor.kt      | 11 ++++++-----
 .../uidebugger/descriptors/ObjectDescriptor.kt    |  4 ----
 .../uidebugger/descriptors/TextViewDescriptor.kt  |  4 ----
 .../uidebugger/descriptors/ViewDescriptor.kt      |  4 ----
 .../uidebugger/descriptors/ViewGroupDescriptor.kt |  4 ----
 .../uidebugger/descriptors/ViewPagerDescriptor.kt |  2 --
 .../uidebugger/descriptors/WindowDescriptor.kt    |  4 ----
 .../flipper/plugins/uidebugger/model/Events.kt    |  4 +++-
 .../flipper/plugins/uidebugger/model/Node.kt      |  7 ++++---
 .../observers/PartialLayoutTraversal.kt           | 13 +++++++------
 .../plugins/uidebugger/observers/TreeObserver.kt  | 15 +++++----------
 20 files changed, 30 insertions(+), 82 deletions(-)

diff --git a/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoDescriptors.kt b/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoDescriptors.kt
index 685ab171d..5bff01a95 100644
--- a/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoDescriptors.kt
+++ b/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoDescriptors.kt
@@ -17,7 +17,6 @@ import com.facebook.litho.DebugComponent
 import com.facebook.litho.LithoView
 
 object LithoViewDescriptor : NodeDescriptor<LithoView> {
-  override fun getId(node: LithoView): String = System.identityHashCode(node).toString()
 
   override fun getName(node: LithoView): String = "LithoView"
 
@@ -45,7 +44,6 @@ const val LithoTag = "Litho"
 class MountedObject(val obj: Any, val descriptor: NodeDescriptor<Any>)
 
 object MountedObjectDescriptor : NodeDescriptor<MountedObject> {
-  override fun getId(node: MountedObject): String = node.descriptor.getId(node.obj)
 
   override fun getBounds(node: MountedObject): Bounds? {
     val bounds = node.descriptor.getBounds(node.obj)
@@ -72,7 +70,6 @@ object MountedObjectDescriptor : NodeDescriptor<MountedObject> {
 }
 
 class DebugComponentDescriptor(val register: DescriptorRegister) : NodeDescriptor<DebugComponent> {
-  override fun getId(node: DebugComponent): String = System.identityHashCode(node).toString()
 
   override fun getName(node: DebugComponent): String {
     return node.component.simpleName
diff --git a/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoObserver.kt b/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoObserver.kt
index 0bf43ae6f..26515e017 100644
--- a/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoObserver.kt
+++ b/android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoObserver.kt
@@ -10,6 +10,7 @@ package com.facebook.flipper.plugins.uidebugger.litho
 import android.util.Log
 import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.core.Context
+import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 import com.facebook.flipper.plugins.uidebugger.observers.TreeObserver
 import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverBuilder
 import com.facebook.litho.LithoView
@@ -22,6 +23,8 @@ class LithoViewTreeObserver(val context: Context) : TreeObserver<LithoView>() {
 
   override fun subscribe(node: Any) {
 
+    Log.i(LogTag, "Subscribing to litho view ${node.nodeId()}")
+
     nodeRef = node as LithoView
 
     val listener: (view: LithoView) -> Unit = { traverseAndSend(context, node) }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt
index bffee456a..2929a36dc 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt
@@ -13,6 +13,7 @@ import com.facebook.flipper.core.FlipperConnection
 import com.facebook.flipper.core.FlipperPlugin
 import com.facebook.flipper.plugins.uidebugger.core.*
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
+import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 import com.facebook.flipper.plugins.uidebugger.model.InitEvent
 import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
 import com.facebook.flipper.plugins.uidebugger.scheduler.Scheduler
@@ -54,8 +55,7 @@ class UIDebuggerFlipperPlugin(
 
     connection.send(
         InitEvent.name,
-        Json.encodeToString(
-            InitEvent.serializer(), InitEvent(rootDescriptor.getId(context.applicationRef))))
+        Json.encodeToString(InitEvent.serializer(), InitEvent(context.applicationRef.nodeId())))
 
     context.treeObserverManager.start()
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
index 96478659a..7fd837e42 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ActivityDescriptor.kt
@@ -13,10 +13,6 @@ import com.facebook.flipper.plugins.uidebugger.core.FragmentTracker
 
 object ActivityDescriptor : ChainedDescriptor<Activity>() {
 
-  override fun onGetId(node: Activity): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: Activity): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
index 079a3453b..644ffda5d 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ApplicationRefDescriptor.kt
@@ -19,10 +19,6 @@ object ApplicationRefDescriptor : ChainedDescriptor<ApplicationRef>() {
     return if (node.activitiesStack.isNotEmpty()) node.activitiesStack.last() else null
   }
 
-  override fun onGetId(node: ApplicationRef): String {
-    return node.application.packageName
-  }
-
   override fun onGetBounds(node: ApplicationRef): Bounds {
     val displayMetrics = Resources.getSystem().getDisplayMetrics()
     return Bounds(0, 0, displayMetrics.widthPixels, displayMetrics.heightPixels)
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
index 995bcd0e2..4e51be3d0 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ButtonDescriptor.kt
@@ -12,10 +12,6 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
 object ButtonDescriptor : ChainedDescriptor<Button>() {
 
-  override fun onGetId(node: Button): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: Button): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ChainedDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ChainedDescriptor.kt
index 3d4491a31..b3a96e039 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ChainedDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ChainedDescriptor.kt
@@ -39,16 +39,6 @@ abstract class ChainedDescriptor<T> : NodeDescriptor<T> {
     return onGetActiveChild(node) ?: mSuper?.getActiveChild(node)
   }
 
-  /**
-   * A globally unique ID used to identify a node in a hierarchy. If your node does not have a
-   * globally unique ID it is fine to rely on [System.identityHashCode].
-   */
-  final override fun getId(node: T): String {
-    return onGetId(node)
-  }
-
-  abstract fun onGetId(node: T): String
-
   /**
    * The name used to identify this node in the inspector. Does not need to be unique. A good
    * default is to use the class name of the node.
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentFrameworkDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentFrameworkDescriptor.kt
index 563f2c663..20469c319 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentFrameworkDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentFrameworkDescriptor.kt
@@ -11,10 +11,6 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
 object FragmentFrameworkDescriptor : ChainedDescriptor<android.app.Fragment>() {
 
-  override fun onGetId(node: android.app.Fragment): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: android.app.Fragment): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentSupportDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentSupportDescriptor.kt
index 023de9f86..2ae61f604 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentSupportDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/FragmentSupportDescriptor.kt
@@ -11,10 +11,6 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
 object FragmentSupportDescriptor : ChainedDescriptor<androidx.fragment.app.Fragment>() {
 
-  override fun onGetId(node: androidx.fragment.app.Fragment): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: androidx.fragment.app.Fragment): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
index 23a95b42a..24fedb17b 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt
@@ -29,11 +29,6 @@ object BaseTags {
 }
 
 interface NodeDescriptor<T> {
-  /**
-   * A globally unique ID used to identify a node in a hierarchy. If your node does not have a
-   * globally unique ID it is fine to rely on [System.identityHashCode].
-   */
-  fun getId(node: T): String
 
   /** Should be w.r.t the direct parent */
   fun getBounds(node: T): Bounds?
@@ -65,3 +60,9 @@ interface NodeDescriptor<T> {
    */
   fun getTags(node: T): Set<String>
 }
+
+typealias Id = Int
+
+fun Any.nodeId(): Id {
+  return System.identityHashCode(this)
+}
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
index 30fb02b08..48c1d756b 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt
@@ -14,10 +14,6 @@ object ObjectDescriptor : NodeDescriptor<Any> {
 
   override fun getActiveChild(node: Any): Any? = null
 
-  override fun getId(node: Any): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun getName(node: Any): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
index fec607ab8..1c8918480 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/TextViewDescriptor.kt
@@ -12,10 +12,6 @@ import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 
 object TextViewDescriptor : ChainedDescriptor<TextView>() {
 
-  override fun onGetId(node: TextView): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: TextView): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
index deb9d4fcd..3cc151f4b 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt
@@ -27,10 +27,6 @@ import java.lang.reflect.Field
 
 object ViewDescriptor : ChainedDescriptor<View>() {
 
-  override fun onGetId(node: View): String {
-    return Integer.toBinaryString(System.identityHashCode(node))
-  }
-
   override fun onGetName(node: View): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
index 5aca34c42..678e12f46 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewGroupDescriptor.kt
@@ -19,10 +19,6 @@ import com.facebook.flipper.plugins.uidebugger.core.FragmentTracker
 
 object ViewGroupDescriptor : ChainedDescriptor<ViewGroup>() {
 
-  override fun onGetId(node: ViewGroup): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: ViewGroup): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
index affb0b3d1..5a62387db 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewPagerDescriptor.kt
@@ -11,8 +11,6 @@ import androidx.viewpager.widget.ViewPager
 
 object ViewPagerDescriptor : ChainedDescriptor<ViewPager>() {
 
-  override fun onGetId(node: ViewPager): String = System.identityHashCode(node).toString()
-
   override fun onGetName(node: ViewPager): String = node.javaClass.simpleName
 
   override fun onGetActiveChild(node: ViewPager): Any? = node.getChildAt(node.currentItem)
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
index e8b3913e5..500722891 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/WindowDescriptor.kt
@@ -11,10 +11,6 @@ import android.view.Window
 
 object WindowDescriptor : ChainedDescriptor<Window>() {
 
-  override fun onGetId(node: Window): String {
-    return System.identityHashCode(node).toString()
-  }
-
   override fun onGetName(node: Window): String {
     return node.javaClass.simpleName
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Events.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Events.kt
index dd5de8c78..0fc3fd6a0 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Events.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Events.kt
@@ -7,8 +7,10 @@
 
 package com.facebook.flipper.plugins.uidebugger.model
 
+import com.facebook.flipper.plugins.uidebugger.descriptors.Id
+
 @kotlinx.serialization.Serializable
-data class InitEvent(val rootId: String) {
+data class InitEvent(val rootId: Id) {
   companion object {
     const val name = "init"
   }
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Node.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Node.kt
index 058d8a72b..ed23555c3 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Node.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/model/Node.kt
@@ -8,16 +8,17 @@
 package com.facebook.flipper.plugins.uidebugger.model
 
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
+import com.facebook.flipper.plugins.uidebugger.descriptors.Id
 
 @kotlinx.serialization.Serializable
 data class Node(
-    val id: String,
+    val id: Id,
     val name: String,
     val attributes: Map<String, InspectableObject>,
     val bounds: Bounds?,
     val tags: Set<String>,
-    val children: List<String>,
-    val activeChild: String?,
+    val children: List<Id>,
+    val activeChild: Id?,
 )
 
 @kotlinx.serialization.Serializable
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/PartialLayoutTraversal.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/PartialLayoutTraversal.kt
index 71e7c4e6e..5cb45641f 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/PartialLayoutTraversal.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/PartialLayoutTraversal.kt
@@ -10,7 +10,9 @@ package com.facebook.flipper.plugins.uidebugger.observers
 import android.util.Log
 import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
+import com.facebook.flipper.plugins.uidebugger.descriptors.Id
 import com.facebook.flipper.plugins.uidebugger.descriptors.NodeDescriptor
+import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 import com.facebook.flipper.plugins.uidebugger.model.Node
 
 /**
@@ -48,7 +50,7 @@ class PartialLayoutTraversal(
 
         val children = descriptor.getChildren(node)
 
-        val childrenIds = mutableListOf<String>()
+        val childrenIds = mutableListOf<Id>()
         val activeChild = descriptor.getActiveChild(node)
 
         for (child in children) {
@@ -56,17 +58,16 @@ class PartialLayoutTraversal(
           // hash code
           val childDescriptor =
               descriptorRegister.descriptorForClassUnsafe(child::class.java).asAny()
-          childrenIds.add(childDescriptor.getId(child))
+          childrenIds.add(child.nodeId())
           // If there is an active child then don't traverse it
           if (activeChild == null) {
             stack.add(child)
           }
         }
-        var activeChildId: String? = null
+        var activeChildId: Id? = null
         if (activeChild != null) {
           stack.add(activeChild)
-          activeChildId =
-              descriptorRegister.descriptorForClassUnsafe(activeChild.javaClass).getId(activeChild)
+          activeChildId = activeChild.nodeId()
         }
 
         val attributes = descriptor.getData(node)
@@ -75,7 +76,7 @@ class PartialLayoutTraversal(
 
         visited.add(
             Node(
-                descriptor.getId(node),
+                node.nodeId(),
                 descriptor.getName(node),
                 attributes,
                 bounds,
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserver.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserver.kt
index be59666b9..bd9ed9d99 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserver.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserver.kt
@@ -10,6 +10,7 @@ package com.facebook.flipper.plugins.uidebugger.observers
 import android.util.Log
 import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.core.Context
+import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 
 /*
  * Represents a stateful observer that manages some subtree in the UI Hierarchy.
@@ -44,19 +45,19 @@ abstract class TreeObserver<T> {
 
     // Add any new observers
     for (observerRoot in observerRootsNodes) {
-      if (!children.containsKey(observerRoot.identityHashCode())) {
+      if (!children.containsKey(observerRoot.nodeId())) {
         context.observerFactory.createObserver(observerRoot, context)?.let { childObserver ->
           Log.d(
               LogTag,
-              "Observer ${this.type} discovered new child of type ${childObserver.type} Node ID ${observerRoot.identityHashCode()}")
+              "Observer ${this.type} discovered new child of type ${childObserver.type} Node ID ${observerRoot.nodeId()}")
           childObserver.subscribe(observerRoot)
-          children[observerRoot.identityHashCode()] = childObserver
+          children[observerRoot.nodeId()] = childObserver
         }
       }
     }
 
     // Remove any old observers
-    val observerRootIds = observerRootsNodes.map { it.identityHashCode() }
+    val observerRootIds = observerRootsNodes.map { it.nodeId() }
     for (childKey in children.keys) {
       if (!observerRootIds.contains(childKey)) {
         children[childKey]?.let { childObserver ->
@@ -81,9 +82,3 @@ abstract class TreeObserver<T> {
     children.clear()
   }
 }
-
-typealias HashCode = Int
-
-fun Any.identityHashCode(): HashCode {
-  return System.identityHashCode(this)
-}