From 32b7a5589f1a59f88cddc1741451ac5459fe6776 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 layout traversal

Summary: The old full traversal was not needed as the partial traversal is a superset of the functionality and it was a pain to maintain both

Reviewed By: lblasa

Differential Revision: D39700216

fbshipit-source-id: 0b028995a59f7c5ea4318add8b0534851ca99547
---
 .../uidebugger/core/LayoutTraversal.kt        | 80 -------------------
 .../uidebugger/core/NativeScanScheduler.kt    | 12 ++-
 2 files changed, 10 insertions(+), 82 deletions(-)
 delete mode 100644 android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/LayoutTraversal.kt

diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/LayoutTraversal.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/LayoutTraversal.kt
deleted file mode 100644
index c9f6f860c..000000000
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/LayoutTraversal.kt
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- * 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.core
-
-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.NodeDescriptor
-import com.facebook.flipper.plugins.uidebugger.model.Node
-
-class LayoutTraversal(
-    private val descriptorRegister: DescriptorRegister,
-    val root: ApplicationRef
-) {
-
-  @Suppress("unchecked_cast")
-  internal fun NodeDescriptor<*>.asAny(): NodeDescriptor<Any> = this as NodeDescriptor<Any>
-
-  /** Traverses the native android hierarchy */
-  fun traverse(): List<Node> {
-
-    val result = mutableListOf<Node>()
-    val stack = mutableListOf<Any>()
-    stack.add(this.root)
-
-    while (stack.isNotEmpty()) {
-      val node = stack.removeLast()
-
-      try {
-        val descriptor = descriptorRegister.descriptorForClassUnsafe(node::class.java).asAny()
-        val children = descriptor.getChildren(node)
-        val activeChild = descriptor.getActiveChild(node)
-
-        val childrenIds = mutableListOf<String>()
-        children.forEach { child ->
-          val childDescriptor =
-              descriptorRegister.descriptorForClassUnsafe(child::class.java).asAny()
-          // It might make sense one day to remove id from the descriptor since its always the
-          // hash code
-          childrenIds.add(childDescriptor.getId(child))
-          // If there is an active child then don't traverse it
-          if (activeChild == null) {
-            stack.add(child)
-          }
-        }
-
-        var activeChildId: String? = null
-        if (activeChild != null) {
-          stack.add(activeChild)
-          activeChildId =
-              descriptorRegister.descriptorForClassUnsafe(activeChild.javaClass).getId(activeChild)
-        }
-
-        val attributes = descriptor.getData(node)
-
-        val bounds = descriptor.getBounds(node)
-        val tags = descriptor.getTags(node)
-
-        result.add(
-            Node(
-                descriptor.getId(node),
-                descriptor.getName(node),
-                attributes,
-                bounds,
-                tags,
-                childrenIds,
-                activeChildId))
-      } catch (exception: Exception) {
-        Log.e(LogTag, "Error while processing node ${node.javaClass.name} $node", exception)
-      }
-    }
-
-    return result
-  }
-}
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/NativeScanScheduler.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/NativeScanScheduler.kt
index 1b1d20e8c..a903f698d 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/NativeScanScheduler.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/NativeScanScheduler.kt
@@ -13,6 +13,8 @@ import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.model.NativeScanEvent
 import com.facebook.flipper.plugins.uidebugger.model.Node
 import com.facebook.flipper.plugins.uidebugger.model.PerfStatsEvent
+import com.facebook.flipper.plugins.uidebugger.observers.PartialLayoutTraversal
+import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
 import com.facebook.flipper.plugins.uidebugger.scheduler.Scheduler
 import kotlinx.serialization.json.Json
 
@@ -23,13 +25,19 @@ data class ScanResult(
     val nodes: List<Node>
 )
 
+/** This is used to stress test the ui debugger, should not be used in production */
 class NativeScanScheduler(val context: Context) : Scheduler.Task<ScanResult> {
-  private val traversal = LayoutTraversal(context.descriptorRegister, context.applicationRef)
+  /**
+   * when you supply no observers the traversal will never halt and will effectively scan the entire
+   * hierarchy
+   */
+  private val emptyObserverFactory = TreeObserverFactory()
+  private val traversal = PartialLayoutTraversal(context.descriptorRegister, emptyObserverFactory)
   private var txId = 0L
 
   override fun execute(): ScanResult {
     val start = System.currentTimeMillis()
-    val nodes = traversal.traverse()
+    val (nodes) = traversal.traverse(context.applicationRef)
     val scanEnd = System.currentTimeMillis()
 
     Log.d(