From dbc4f2b63b6b3bb5b57e392f01248cfad43b3589 Mon Sep 17 00:00:00 2001
From: Philip O'Toole <philip.otoole@yahoo.com>
Date: Tue, 6 Feb 2024 02:56:19 -0500
Subject: [PATCH] Small refactor of Stale Reads check

---
 CHANGELOG.md   |  1 +
 store/store.go | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1da5612f..30607f9c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 ### Implementation changes and bug fixes
 - [PR #1670](https://github.com/rqlite/rqlite/pull/1670): Improve error message when query on remote node fails.
 - [PR #1671](https://github.com/rqlite/rqlite/pull/1670): Minor optimizations to Unified Request processing.
+- [PR #1674](https://github.com/rqlite/rqlite/pull/1674): Small refactor of _Stale Reads_ check.
 
 ## 8.19.0 (February 3rd 2024)
 This release allows you to set a maximum amount of a time a query will run. If the query does not complete within the set time, an error will be returned.
diff --git a/store/store.go b/store/store.go
index fb2dfbd5..6b9db35c 100644
--- a/store/store.go
+++ b/store/store.go
@@ -1138,8 +1138,7 @@ func (s *Store) Query(qr *proto.QueryRequest) ([]*proto.QueryRows, error) {
 		return nil, ErrNotLeader
 	}
 
-	if s.raft.State() != raft.Leader && qr.Level == proto.QueryRequest_QUERY_REQUEST_LEVEL_NONE &&
-		qr.Freshness > 0 && time.Since(s.raft.LastContact()).Nanoseconds() > qr.Freshness {
+	if qr.Level == proto.QueryRequest_QUERY_REQUEST_LEVEL_NONE && s.isStaleRead(qr.Freshness) {
 		return nil, ErrStaleRead
 	}
 
@@ -1179,11 +1178,8 @@ func (s *Store) Request(eqr *proto.ExecuteQueryRequest) ([]*proto.ExecuteQueryRe
 			}
 			return resp
 		}
-		if eqr.Level == proto.QueryRequest_QUERY_REQUEST_LEVEL_NONE {
-			if !isLeader && eqr.Freshness > 0 &&
-				time.Since(s.raft.LastContact()).Nanoseconds() > eqr.Freshness {
-				return nil, ErrStaleRead
-			}
+		if eqr.Level == proto.QueryRequest_QUERY_REQUEST_LEVEL_NONE && s.isStaleRead(eqr.Freshness) {
+			return nil, ErrStaleRead
 		} else if eqr.Level == proto.QueryRequest_QUERY_REQUEST_LEVEL_WEAK {
 			if !isLeader {
 				return nil, ErrNotLeader
@@ -1806,6 +1802,13 @@ func (s *Store) updateAppliedIndex() chan struct{} {
 	return done
 }
 
+func (s *Store) isStaleRead(freshness int64) bool {
+	if freshness == 0 || s.raft.State() == raft.Leader {
+		return false
+	}
+	return time.Since(s.raft.LastContact()).Nanoseconds() > freshness
+}
+
 type fsmExecuteResponse struct {
 	results []*proto.ExecuteResult
 	error   error