From 0d6795b37870c124ac73de44c76bbeeaf51999f7 Mon Sep 17 00:00:00 2001
From: Erik Grinaker <erik@grinaker.org>
Date: Tue, 14 Nov 2023 20:08:52 +0100
Subject: [PATCH] Return log index from `raft::Log::append()`

---
 src/raft/log.rs         | 13 +++++--------
 src/raft/node/leader.rs |  4 ++--
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/src/raft/log.rs b/src/raft/log.rs
index d467a4f35..ab136aa97 100644
--- a/src/raft/log.rs
+++ b/src/raft/log.rs
@@ -107,14 +107,14 @@ impl Log {
         self.store.set_metadata(&Key::TermVote.encode(), bincode::serialize(&(term, voted_for))?)
     }
 
-    /// Appends a command to the log, returning the entry.
-    pub fn append(&mut self, term: Term, command: Option<Vec<u8>>) -> Result<Entry> {
+    /// Appends a command to the log, returning the log index.
+    pub fn append(&mut self, term: Term, command: Option<Vec<u8>>) -> Result<Index> {
         let entry = Entry { index: self.last_index + 1, term, command };
         debug!("Appending log entry {}: {:?}", entry.index, entry);
         self.store.append(bincode::serialize(&entry)?)?;
         self.last_index = entry.index;
         self.last_term = entry.term;
-        Ok(entry)
+        Ok(entry.index)
     }
 
     /// Commits entries up to and including an index.
@@ -220,10 +220,7 @@ mod tests {
         let (mut l, _) = setup()?;
         assert_eq!(Ok(None), l.get(1));
 
-        assert_eq!(
-            Entry { index: 1, term: 3, command: Some(vec![0x01]) },
-            l.append(3, Some(vec![0x01]))?
-        );
+        assert_eq!(1, l.append(3, Some(vec![0x01]))?);
         assert_eq!(Some(Entry { index: 1, term: 3, command: Some(vec![0x01]) }), l.get(1)?);
         assert_eq!(None, l.get(2)?);
 
@@ -237,7 +234,7 @@ mod tests {
     #[test]
     fn append_none() -> Result<()> {
         let (mut l, _) = setup()?;
-        assert_eq!(Entry { index: 1, term: 3, command: None }, l.append(3, None)?);
+        assert_eq!(1, l.append(3, None)?);
         assert_eq!(Some(Entry { index: 1, term: 3, command: None }), l.get(1)?);
         Ok(())
     }
diff --git a/src/raft/node/leader.rs b/src/raft/node/leader.rs
index df118601a..19dafc64e 100644
--- a/src/raft/node/leader.rs
+++ b/src/raft/node/leader.rs
@@ -44,11 +44,11 @@ impl RoleNode<Leader> {
 
     /// Appends an entry to the log and replicates it to peers.
     pub fn append(&mut self, command: Option<Vec<u8>>) -> Result<u64> {
-        let entry = self.log.append(self.term, command)?;
+        let index = self.log.append(self.term, command)?;
         for peer in self.peers.iter() {
             self.replicate(peer)?;
         }
-        Ok(entry.index)
+        Ok(index)
     }
 
     /// Commits any pending log entries.