etcdserver/*, wal/*:Add comments, clean up error messages and tests

etcdserver/raft.go

@@ -250,8 +250,9 @@ func (r *raftNode) start(rh *raftReadyHandler) {
 					// Force WAL to fsync its hard state before Release() releases
 					// old data from the WAL. Otherwise could get an error like:
 					// panic: tocommit(107) is out of range [lastIndex(84)]. Was the raft log corrupted, truncated, or lost?
+					// See https://github.com/etcd-io/etcd/issues/10219 for more details.
 					if err := r.storage.Sync(); err != nil {
-						log.Fatal(err)
+						r.lg.Fatal("failed to sync Raft snapshot", zap.Error(err))
 					}
 
 					// etcdserver now claim the snapshot has been persisted onto the disk
@@ -263,7 +264,7 @@ func (r *raftNode) start(rh *raftReadyHandler) {
 					// gofail: var raftAfterApplySnap struct{}
 
 					if err := r.storage.Release(rd.Snapshot); err != nil {
-						log.Fatal(err)
+						r.lg.Fatal("failed to release Raft wal", zap.Error(err))
 					}
 					// gofail: var raftAfterWALRelease struct{}
 				}

etcdserver/server_test.go

@@ -1162,7 +1162,7 @@ func TestTriggerSnap(t *testing.T) {
 		// each operation is recorded as a Save
 		// (SnapshotCount+1) * Puts + SaveSnap = (SnapshotCount+1) * Save + SaveSnap + Release
 		if len(gaction) != wcnt {
-			fmt.Println("gaction", gaction)
+			t.Logf("gaction: %v", gaction)
 			t.Fatalf("len(action) = %d, want %d", len(gaction), wcnt)
 		}
 

wal/wal.go

@@ -583,7 +583,7 @@ func ValidSnapshotEntries(lg *zap.Logger, walDir string) ([]walpb.Snapshot, erro
 			n++
 		}
 	}
-	snaps = snaps[:n]
+	snaps = snaps[:n:n]
 
 	return snaps, nil
 }

wal/wal_test.go

@@ -1011,9 +1011,11 @@ func TestValidSnapshotEntries(t *testing.T) {
 	defer os.RemoveAll(p)
 	snap0 := walpb.Snapshot{Index: 0, Term: 0}
 	snap1 := walpb.Snapshot{Index: 1, Term: 1}
+	state1 := raftpb.HardState{Commit: 1, Term: 1}
 	snap2 := walpb.Snapshot{Index: 2, Term: 1}
 	snap3 := walpb.Snapshot{Index: 3, Term: 2}
-	snap4 := walpb.Snapshot{Index: 4, Term: 2}
+	state2 := raftpb.HardState{Commit: 3, Term: 2}
+	snap4 := walpb.Snapshot{Index: 4, Term: 2} // will be orphaned since the last committed entry will be snap3
 	func() {
 		w, err := Create(zap.NewExample(), p, nil)
 		if err != nil {
@@ -1025,8 +1027,7 @@ func TestValidSnapshotEntries(t *testing.T) {
 		if err = w.SaveSnapshot(snap1); err != nil {
 			t.Fatal(err)
 		}
-		state := raftpb.HardState{Commit: 1, Term: 1}
-		if err = w.Save(state, nil); err != nil {
+		if err = w.Save(state1, nil); err != nil {
 			t.Fatal(err)
 		}
 		if err = w.SaveSnapshot(snap2); err != nil {
@@ -1035,7 +1036,6 @@ func TestValidSnapshotEntries(t *testing.T) {
 		if err = w.SaveSnapshot(snap3); err != nil {
 			t.Fatal(err)
 		}
-		state2 := raftpb.HardState{Commit: 3, Term: 2}
 		if err = w.Save(state2, nil); err != nil {
 			t.Fatal(err)
 		}
@@ -1048,12 +1048,7 @@ func TestValidSnapshotEntries(t *testing.T) {
 		t.Fatal(err)
 	}
 	expected := []walpb.Snapshot{snap0, snap1, snap2, snap3}
-	if len(walSnaps) != len(expected) {
-		t.Fatalf("expected 4 walSnaps, got %d", len(expected))
-	}
-	for i := 0; i < len(expected); i++ {
-		if walSnaps[i].Index != expected[i].Index || walSnaps[i].Term != expected[i].Term {
-			t.Errorf("expected walSnaps %+v at index %d, got %+v", expected[i], i, walSnaps[i])
-		}
+	if !reflect.DeepEqual(walSnaps, expected) {
+		t.Errorf("expected walSnaps %+v, got %+v", expected, walSnaps)
 	}
 }