From 2052c8507491c9c4039ef10c29696f15b209b1b4 Mon Sep 17 00:00:00 2001
From: Jake Wharton <jw@squareup.com>
Date: Fri, 8 Nov 2024 14:03:52 -0500
Subject: [PATCH] Switch back to MutableMap to avoid scatter map bug

Sometimes the scatter-based maps can return values from other keys when inserting a new key. See https://issuetracker.google.com/issues/378077858.
---
 .../protocol/host/HostProtocolAdapter.kt       | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/redwood-protocol-host/src/commonMain/kotlin/app/cash/redwood/protocol/host/HostProtocolAdapter.kt b/redwood-protocol-host/src/commonMain/kotlin/app/cash/redwood/protocol/host/HostProtocolAdapter.kt
index 1b5649d4d8..faa5bada9e 100644
--- a/redwood-protocol-host/src/commonMain/kotlin/app/cash/redwood/protocol/host/HostProtocolAdapter.kt
+++ b/redwood-protocol-host/src/commonMain/kotlin/app/cash/redwood/protocol/host/HostProtocolAdapter.kt
@@ -36,6 +36,7 @@ import app.cash.redwood.protocol.RedwoodVersion
 import app.cash.redwood.protocol.WidgetTag
 import app.cash.redwood.widget.ChangeListener
 import app.cash.redwood.widget.Widget
+import kotlin.collections.mutableMapOf
 import kotlin.native.ObjCName
 
 /**
@@ -61,7 +62,7 @@ public class HostProtocolAdapter<W : Any>(
   }
 
   private val nodes =
-    mutableIntObjectMapOf<ProtocolNode<W>>(Id.Root.value, RootProtocolNode(container))
+    mutableMapOf<Int, ProtocolNode<W>>(Id.Root.value to RootProtocolNode(container))
 
   private val removeNodeById = IdVisitor { nodes.remove(it.value) }
 
@@ -173,7 +174,7 @@ public class HostProtocolAdapter<W : Any>(
   public fun close() {
     closed = true
 
-    nodes.forEachValue { node ->
+    nodes.values.forEach { node ->
       node.detach()
     }
     nodes.clear()
@@ -235,9 +236,10 @@ public class HostProtocolAdapter<W : Any>(
       // Must have a Create node that precedes it.
       if (lastCreatedId != change.id) continue
 
-      idToNode[change.id.value] = ReuseNode(
-        widgetId = change.id,
-        childrenTag = ChildrenTag.Root,
+      idToNode[lastCreatedId.value] = ReuseNode(
+        widgetId = lastCreatedId,
+        // This is the root of the reuse tree, so it will never have a children tag from a parent.
+        childrenTag = ChildrenTag(-1),
       )
     }
 
@@ -359,19 +361,17 @@ public class HostProtocolAdapter<W : Any>(
      * descendants into the nodes map.
      */
     fun assignPooledNodeRecursive(
-      nodes: MutableIntObjectMap<ProtocolNode<W>>,
+      nodes: MutableMap<Int, ProtocolNode<W>>,
       changesAndNulls: Array<Change?>,
       pooled: ProtocolNode<W>,
     ) {
       // Reuse the node.
+      pooled.id = widgetId
       val old = nodes.put(widgetId.value, pooled)
       require(old == null) {
         "Insert attempted to replace existing widget with ID ${widgetId.value}"
       }
 
-      val skippedCreate = changesAndNulls[changeIndexForCreate] as Create
-      pooled.id = skippedCreate.id
-
       // Remove the corresponding changes that we avoided by node reuse. We don't clear the 'Add'
       // that adds the node to its new parent.
       changesAndNulls[changeIndexForCreate] = null