From 1111a8bd57f7567e5d8e1f822e3abd56cd131104 Mon Sep 17 00:00:00 2001
From: Weny Xu <wenymedia@gmail.com>
Date: Wed, 25 Dec 2024 10:38:47 +0800
Subject: [PATCH] chore: add log for converting region to follower (#5222)

* chore: add log for converting region to follower

* chore: apply suggestions from CR
---
 src/mito2/src/region.rs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/mito2/src/region.rs b/src/mito2/src/region.rs
index 41fb239a58..0a246b393f 100644
--- a/src/mito2/src/region.rs
+++ b/src/mito2/src/region.rs
@@ -447,7 +447,26 @@ impl ManifestContext {
     pub(crate) fn set_role(&self, next_role: RegionRole, region_id: RegionId) {
         match next_role {
             RegionRole::Follower => {
-                self.state.store(RegionRoleState::Follower);
+                match self.state.fetch_update(|state| {
+                    if !matches!(state, RegionRoleState::Follower) {
+                        Some(RegionRoleState::Follower)
+                    } else {
+                        None
+                    }
+                }) {
+                    Ok(state) => info!(
+                        "Convert region {} to follower, previous role state: {:?}",
+                        region_id, state
+                    ),
+                    Err(state) => {
+                        if state != RegionRoleState::Follower {
+                            warn!(
+                                "Failed to convert region {} to follower, current role state: {:?}",
+                                region_id, state
+                            )
+                        }
+                    }
+                }
             }
             RegionRole::Leader => {
                 match self.state.fetch_update(|state| {