From 5b649379a3ff509e38afa25eb7d1403fa83d0529 Mon Sep 17 00:00:00 2001
From: Paul Masurel <paul@quickwit.io>
Date: Thu, 7 Mar 2024 16:07:04 +0900
Subject: [PATCH] CR comments

---
 ALGORITHM.md          |  6 ++++--
 chitchat/src/state.rs | 10 +++++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/ALGORITHM.md b/ALGORITHM.md
index 0ddd6aa..bef4c6b 100644
--- a/ALGORITHM.md
+++ b/ALGORITHM.md
@@ -2,10 +2,11 @@ Chitchat relies on an extension of the Scuttlebutt reconciliation algorithm, to
 - Key-Value deletion
 - Member leaving the cluster.
 
-For simplification, we will just discuss the replication of a single map on a cluster of n node, one which only one node can write to.
+For simplification, we will just discuss the replication of a single map on a cluster of n node, on which only one node can write to.
+
 (In scuttlebutt, each node has ownership over such a map.)
 
-There are two kinds of update events on this map:
+There are two kinds of update event on this map:
 - Set(K, V)
 - Deletion(K)
 
@@ -34,6 +35,7 @@ node will send two parameters describing how much of the state is replicated:
 - `max_version`: One big difference with reliable broadcast, is that this `max version` does NOT mean that the node's state reflects all of the events earlier than
 `max_version`. Rather, it says that if the node were to receive all of the events within between `max_version` and $V$ then it will end up to date.
 The difference is subtle, but comes from an important optimization of scuttlebutt.
+
 If a node asks for an update above $max_version = m$, and that for a given key $k$ there are two updates after $m$, there is no need to send the first one: it will eventually be overridden by the second one.
 
 - `last_gc_version`: Rather than being deleted right away, the algorithm is using a tombstone mechanism. Key entries are kept by marked as deleted. From the client point of view, everything looks like the key really has been deleted. Eventually, in order
diff --git a/chitchat/src/state.rs b/chitchat/src/state.rs
index 071b39d..ceb8162 100644
--- a/chitchat/src/state.rs
+++ b/chitchat/src/state.rs
@@ -205,8 +205,16 @@ impl NodeState {
             current_last_gc_version=self.last_gc_version,
             "resetting node");
         *self = NodeState::new(node_delta.chitchat_id.clone(), self.listeners.clone());
+        // The node_delta max_version  whe
         if let Some(max_version) = node_delta.max_version {
-            self.max_version = max_version;
+            if node_delta.key_values.is_empty() {
+                self.max_version = max_version;
+            } else {
+                warn!(
+                    "Received a delta with a max_version, and key_values as well. This is \
+                     unexpected, please report."
+                );
+            }
         }
         // We need to reset our `last_gc_version`.
         self.last_gc_version = node_delta.last_gc_version;