Add Id to node descriptor interface

Summary:
There were 2 situations where the UI hadn't changed but we were sending a nodes with a different Id accross traversals which confuses things on the desktop

1. By removing the litho observer we are repeatidly scanning the entire hierachy on scroll or when a video plays. The debug component that represents litho views are not stable, they are generated each time even if the underlying component is the same
2. Offset child is generated by us each time and the old id refered to the generated offset child not the underlying object

This diff addresses these 2 cases by allowing a descriptor to choose the ID.

The nodeId convience method was used in a lot of places. For the places where the id ended up in the protocol we have migrated to the descriptors getID. In some other places it is only used internally or for logging.  In this case I have renamed the method and changed the return type from Id to int so it cant be accidently used in the protocol

Reviewed By: lblasa

Differential Revision: D41307239

fbshipit-source-id: 655b230180a6d02d66888e86b2293eead3385455

android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt

@@ -12,9 +12,9 @@ import android.util.Log
 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.ApplicationRefDescriptor
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
 import com.facebook.flipper.plugins.uidebugger.descriptors.MetadataRegister
-import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 import com.facebook.flipper.plugins.uidebugger.model.InitEvent
 import com.facebook.flipper.plugins.uidebugger.model.MetadataUpdateEvent
 import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
@@ -51,7 +51,9 @@ class UIDebuggerFlipperPlugin(
 
     connection.send(
         InitEvent.name,
-        Json.encodeToString(InitEvent.serializer(), InitEvent(context.applicationRef.nodeId())))
+        Json.encodeToString(
+            InitEvent.serializer(),
+            InitEvent(ApplicationRefDescriptor.getId(context.applicationRef))))
 
     connection.send(
         MetadataUpdateEvent.name,

android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/NativeScanScheduler.kt

@@ -10,8 +10,8 @@ package com.facebook.flipper.plugins.uidebugger.core
 import android.os.Looper
 import android.util.Log
 import com.facebook.flipper.plugins.uidebugger.LogTag
+import com.facebook.flipper.plugins.uidebugger.descriptors.ApplicationRefDescriptor
 import com.facebook.flipper.plugins.uidebugger.descriptors.MetadataRegister
-import com.facebook.flipper.plugins.uidebugger.descriptors.nodeId
 import com.facebook.flipper.plugins.uidebugger.model.MetadataUpdateEvent
 import com.facebook.flipper.plugins.uidebugger.model.Node
 import com.facebook.flipper.plugins.uidebugger.model.PerfStatsEvent
@@ -66,7 +66,10 @@ class NativeScanScheduler(val context: Context) : Scheduler.Task<ScanResult> {
         Json.encodeToString(
             SubtreeUpdateEvent.serializer(),
             SubtreeUpdateEvent(
-                input.txId, observerType, context.applicationRef.nodeId(), input.nodes))
+                input.txId,
+                observerType,
+                ApplicationRefDescriptor.getId(context.applicationRef),
+                input.nodes))
     val serializationEnd = System.currentTimeMillis()
 
     context.connectionRef.connection?.send(

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt

@@ -31,8 +31,13 @@ object BaseTags {
   val AccessibleNativeAndroid = setOf(Android, Native, Accessibility)
 }
 
+typealias Id = Int
+
 interface NodeDescriptor<T> {
 
+  /** Used to detect the same node across traversals */
+  fun getId(node: T): Id = System.identityHashCode(node)
+
   /** Should be w.r.t the direct parent */
   fun getBounds(node: T): Bounds
 
@@ -76,9 +81,3 @@ interface NodeDescriptor<T> {
    */
   fun getTags(node: T): Set<String>
 }
-
-typealias Id = Int
-
-fun Any.nodeId(): Id {
-  return System.identityHashCode(this)
-}

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/OffsetChildDescriptor.kt

@@ -21,6 +21,8 @@ class OffsetChild(val child: Any, val descriptor: NodeDescriptor<Any>, val x: In
 
 object OffsetChildDescriptor : NodeDescriptor<OffsetChild> {
 
+  override fun getId(node: OffsetChild): Id = node.descriptor.getId(node.child)
+
   override fun getBounds(node: OffsetChild): Bounds {
     val bounds = node.descriptor.getBounds(node.child)
     return Bounds(node.x, node.y, bounds.width, bounds.height)

android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserver.kt

@@ -13,7 +13,7 @@ import com.facebook.flipper.plugins.uidebugger.common.BitmapPool
 import com.facebook.flipper.plugins.uidebugger.core.Context
 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.util.objectIdentity
 
 /*
  * Represents a stateful observer that manages some subtree in the UI Hierarchy.
@@ -49,19 +49,19 @@ abstract class TreeObserver<T> {
 
     // Add any new observers
     observableRoots.forEach { observable ->
-      if (!children.containsKey(observable.nodeId())) {
+      if (!children.containsKey(observable.objectIdentity())) {
         context.observerFactory.createObserver(observable, context)?.let { observer ->
           Log.d(
               LogTag,
-              "Observer ${this.type} discovered new child of type ${observer.type} Node ID ${observable.nodeId()}")
+              "Observer ${this.type} discovered new child of type ${observer.type} Node ID ${observable.objectIdentity()}")
           observer.subscribe(observable)
-          children[observable.nodeId()] = observer
+          children[observable.objectIdentity()] = observer
         }
       }
     }
 
     // Remove any old observers
-    val observableRootsIdentifiers = observableRoots.map { it.nodeId() }
+    val observableRootsIdentifiers = observableRoots.map { it.objectIdentity() }
     val removables = mutableListOf<Id>()
     children.keys.forEach { key ->
       if (!observableRootsIdentifiers.contains(key)) {
@@ -92,7 +92,7 @@ abstract class TreeObserver<T> {
     context.treeObserverManager.enqueueUpdate(
         SubtreeUpdate(
             type,
-            root.nodeId(),
+            root.objectIdentity(),
             visitedNodes,
             startTimestamp,
             traversalCompleteTime,

android/src/main/java/com/facebook/flipper/plugins/uidebugger/traversal/PartialLayoutTraversal.kt

@@ -12,7 +12,6 @@ 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
 import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
 
@@ -55,7 +54,7 @@ class PartialLayoutTraversal(
         if (shallow.contains(node)) {
           visited.add(
               Node(
-                  node.nodeId(),
+                  descriptor.getId(node),
                   descriptor.getQualifiedName(node),
                   descriptor.getName(node),
                   emptyMap(),
@@ -71,14 +70,18 @@ class PartialLayoutTraversal(
         val children = descriptor.getChildren(node)
 
         val activeChild = descriptor.getActiveChild(node)
+
         var activeChildId: Id? = null
         if (activeChild != null) {
-          activeChildId = activeChild.nodeId()
+          val activeChildDescriptor =
+              descriptorRegister.descriptorForClassUnsafe(activeChild.javaClass)
+          activeChildId = activeChildDescriptor.getId(activeChild)
         }
 
         val childrenIds = mutableListOf<Id>()
         children.forEach { child ->
-          childrenIds.add(child.nodeId())
+          val childDescriptor = descriptorRegister.descriptorForClassUnsafe(child.javaClass)
+          childrenIds.add(childDescriptor.getId(child))
           stack.add(child)
           // If there is an active child then don't traverse it
           if (activeChild != null && activeChild != child) {
@@ -91,7 +94,7 @@ class PartialLayoutTraversal(
         val tags = descriptor.getTags(node)
         visited.add(
             Node(
-                node.nodeId(),
+                descriptor.getId(node),
                 descriptor.getQualifiedName(node),
                 descriptor.getName(node),
                 attributes,

android/src/main/java/com/facebook/flipper/plugins/uidebugger/util/ObjectIdentity.kt

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.flipper.plugins.uidebugger.util
+
+fun Any.objectIdentity(): Int {
+  return System.identityHashCode(this)
+}