Replace StateNetworkInfo metadata atomically

Signed-off-by: Michael Tinker <[email protected]>

hedera-node/hedera-app/src/main/java/com/hedera/node/app/info/StateNetworkInfo.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023-2024 Hedera Hashgraph, LLC
+ * Copyright (C) 2023-2025 Hedera Hashgraph, LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,7 +56,14 @@ public class StateNetworkInfo implements NetworkInfo {
      */
     private final Roster activeRoster;
 
-    private final Map<Long, NodeInfo> nodeInfos;
+    /**
+     * Non-final because we need {@code handleTransaction} to be able to swap in an
+     * updated map atomically, without giving a pre-handle thread a temporary view of
+     * an empty map. (Note that {@code handleTransaction}'s updates will only change
+     * <i>metadata</i> of nodes, but not the set of nodes itself; so pre-handle threads
+     * can use any version of the map to test for address book membership.)
+     */
+    private Map<Long, NodeInfo> nodeInfos;
 
     /**
      * Constructs a new network information provider from the given state, roster, selfID, and configuration provider.
@@ -113,8 +120,7 @@ public boolean containsNode(final long nodeId) {
 
     @Override
     public void updateFrom(@NonNull final State state) {
-        nodeInfos.clear();
-        nodeInfos.putAll(nodeInfosFrom(state));
+        nodeInfos = nodeInfosFrom(state);
     }
 
     /**