Initialize vlog before starting compactions in db.Open

db.go

@@ -331,6 +331,9 @@ func Open(opt Options) (db *DB, err error) {
 		return nil, err
 	}
 
+	// Initialize vlog struct.
+	db.vlog.init(db)
+
 	if !opt.ReadOnly {
 		db.closers.compactors = y.NewCloser(1)
 		db.lc.startCompact(db.closers.compactors)

value.go

@@ -1061,13 +1061,15 @@ func (vlog *valueLog) replayLog(lf *logFile, offset uint32, replayFn logEntry) e
 	return nil
 }
 
-func (vlog *valueLog) open(db *DB, ptr valuePointer, replayFn logEntry) error {
+// init initializes the value log struct. This initialization needs to happen
+// before compactions start.
+func (vlog *valueLog) init(db *DB) {
 	vlog.opt = db.opt
 	vlog.db = db
 	// We don't need to open any vlog files or collect stats for GC if DB is opened
 	// in InMemory mode. InMemory mode doesn't create any files/directories on disk.
 	if vlog.opt.InMemory {
-		return nil
+		return
 	}
 	vlog.dirPath = vlog.opt.ValueDir
 	vlog.elog = y.NoEventLog
@@ -1080,6 +1082,15 @@ func (vlog *valueLog) open(db *DB, ptr valuePointer, replayFn logEntry) error {
 		closer:    y.NewCloser(1),
 		flushChan: make(chan map[uint32]int64, 16),
 	}
+}
+
+func (vlog *valueLog) open(db *DB, ptr valuePointer, replayFn logEntry) error {
+	// We don't need to open any vlog files or collect stats for GC if DB is opened
+	// in InMemory mode. InMemory mode doesn't create any files/directories on disk.
+	if db.opt.InMemory {
+		return nil
+	}
+
 	go vlog.flushDiscardStats()
 	if err := vlog.populateFilesMap(); err != nil {
 		return err

value_test.go

@@ -412,6 +412,7 @@ func TestValueGC4(t *testing.T) {
 	err = kv.vlog.Close()
 	require.NoError(t, err)
 
+	kv.vlog.init(kv)
 	err = kv.vlog.open(kv, valuePointer{Fid: 2}, kv.replayFunction())
 	require.NoError(t, err)
 
@@ -642,8 +643,11 @@ func TestPartialAppendToValueLog(t *testing.T) {
 	checkKeys(t, kv, [][]byte{k3})
 	// Replay value log from beginning, badger head is past k2.
 	require.NoError(t, kv.vlog.Close())
-	require.NoError(t,
-		kv.vlog.open(kv, valuePointer{Fid: 0}, kv.replayFunction()))
+
+	kv.vlog.init(kv)
+	require.NoError(
+		t, kv.vlog.open(kv, valuePointer{Fid: 0}, kv.replayFunction()),
+	)
 	require.NoError(t, kv.Close())
 }