Merge pull request #1525 from rqlite/is-leader-has-leader

Make Store Notify logic clearer

CHANGELOG.md

@@ -3,6 +3,7 @@
 - [PR #1522](https://github.com/rqlite/rqlite/pull/1522): Minor refactoring of main module.
 - [PR #1523](https://github.com/rqlite/rqlite/pull/1523): Move download functionality into _restore_ module.
 - [PR #1524](https://github.com/rqlite/rqlite/pull/1524): Disco mode not supported when explicitly joining.
+- [PR #1525](https://github.com/rqlite/rqlite/pull/1525): Make Store _Notify_ logic clearer.
 
 ## 8.13.4 (December 23rd 2023)
 This release makes sure the version information is correctly recorded in the released binaries. There are no functional changes.

store/store.go

@@ -675,6 +675,11 @@ func (s *Store) IsLeader() bool {
 	return s.raft.State() == raft.Leader
 }
 
+// HasLeader returns true if the cluster has a leader, false otherwise.
+func (s *Store) HasLeader() bool {
+	return s.raft.Leader() != ""
+}
+
 // IsVoter returns true if the current node is a voter in the cluster. If there
 // is no reference to the current node in the current cluster configuration then
 // false will also be returned.
@@ -1352,8 +1357,13 @@ func (s *Store) Notify(nr *command.NotifyRequest) error {
 	s.notifyMu.Lock()
 	defer s.notifyMu.Unlock()
 
-	if s.BootstrapExpect == 0 || s.bootstrapped || s.raft.Leader() != "" {
+	if s.BootstrapExpect == 0 || s.bootstrapped || s.HasLeader() {
 		// There is no reason this node will bootstrap.
+		//
+		// - Read-only nodes require that BootstrapExpect is set to 0, so this
+		// block ensures that notifying a read-only node will not cause a bootstrap.
+		// - If the node is already bootstrapped, then there is nothing to do.
+		// - If the node already has a leader, then no bootstrapping is required.
 		return nil
 	}
 

store/store_test.go

@@ -2627,6 +2627,56 @@ func Test_IsLeader(t *testing.T) {
 	if !s.IsLeader() {
 		t.Fatalf("single node is not leader!")
 	}
+	if !s.HasLeader() {
+		t.Fatalf("single node does not have leader!")
+	}
+}
+
+func Test_MultiNodeIsLeaderHasLeader(t *testing.T) {
+	s0, ln0 := mustNewStore(t)
+	defer ln0.Close()
+	if err := s0.Open(); err != nil {
+		t.Fatalf("failed to open single-node store: %s", err.Error())
+	}
+	defer s0.Close(true)
+	if err := s0.Bootstrap(NewServer(s0.ID(), s0.Addr(), true)); err != nil {
+		t.Fatalf("failed to bootstrap single-node store: %s", err.Error())
+	}
+	if _, err := s0.WaitForLeader(10 * time.Second); err != nil {
+		t.Fatalf("Error waiting for leader: %s", err)
+	}
+
+	s1, ln1 := mustNewStore(t)
+	defer ln1.Close()
+	if err := s1.Open(); err != nil {
+		t.Fatalf("failed to open single-node store: %s", err.Error())
+	}
+	defer s1.Close(true)
+	if err := s1.Bootstrap(NewServer(s1.ID(), s1.Addr(), true)); err != nil {
+		t.Fatalf("failed to bootstrap single-node store: %s", err.Error())
+	}
+
+	// Join the second node to the first.
+	if err := s0.Join(joinRequest(s1.ID(), s1.Addr(), true)); err != nil {
+		t.Fatalf("failed to join to node at %s: %s", s0.Addr(), err.Error())
+	}
+	_, err := s1.WaitForLeader(10 * time.Second)
+	if err != nil {
+		t.Fatalf("failed to get leader address on follower: %s", err.Error())
+	}
+
+	if !s0.IsLeader() {
+		t.Fatalf("s0 is not leader")
+	}
+	if !s0.HasLeader() {
+		t.Fatalf("s0 does not have a leader")
+	}
+	if s1.IsLeader() {
+		t.Fatalf("s1 is leader")
+	}
+	if !s1.HasLeader() {
+		t.Fatalf("s1 does not have a leader")
+	}
 }
 
 func Test_IsVoter(t *testing.T) {