fix(badgerd/gossip): skip stale startup election when leader is already known

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

Author: Adphi

internal/badgerd/replication/gossip/gossip.go

@@ -295,6 +295,9 @@ func (r *Gossip) run(ctx context.Context) {
 		if ctx.Err() != nil {
 			return
 		}
+		if r.HasLeader() {
+			return
+		}
 		r.Elect(ctx)
 	}()
 }

internal/badgerd/replication/gossip/gossip_test.go

@@ -1,15 +1,17 @@
 package gossip
 
 import (
+	"context"
 	"testing"
 	"time"
 
+	"github.com/hashicorp/memberlist"
+	"github.com/stretchr/testify/assert"
 	pubsub "go.linka.cloud/pubsub/typed"
 	"google.golang.org/grpc"
 
-	"github.com/stretchr/testify/assert"
-
 	"go.linka.cloud/protodb/internal/badgerd/replication"
+	pb2 "go.linka.cloud/protodb/internal/badgerd/replication/gossip/pb"
 )
 
 func TestGossipSimpleMethodsTable(t *testing.T) {
@@ -49,3 +51,37 @@ func TestGossipSimpleMethodsTable(t *testing.T) {
 	assert.NotNil(t, conn)
 	assert.Same(t, cc, conn)
 }
+
+func TestRunSkipsElectionWhenLeaderAlreadyKnown(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	r := &Gossip{
+		ctx:          ctx,
+		name:         "self",
+		shuttingDown: NewAtomic(false),
+		leading:      NewAtomic(false),
+		leaderName:   NewAtomic("peer"),
+		bootNodes:    []string{"peer"},
+		ready:        make(chan struct{}),
+		events:       make(chan memberlist.NodeEvent),
+		converged:    make(chan struct{}),
+		pub:          pubsub.NewPublisher[string](time.Second, 2),
+	}
+	r.meta.Store(&pb2.Meta{LocalVersion: 1})
+	close(r.converged)
+
+	r.run(ctx)
+	t.Cleanup(func() { close(r.events) })
+
+	time.Sleep(1500 * time.Millisecond)
+
+	assert.Equal(t, "peer", r.CurrentLeader())
+	assert.False(t, r.IsLeader())
+	assert.False(t, r.HasLeader() && r.CurrentLeader() == "self")
+	select {
+	case <-r.ready:
+		t.Fatal("expected ready to stay open")
+	default:
+	}
+}