cleanup

s3/s3.go

@@ -570,10 +570,10 @@ func (r *Replica) snapshot(ctx context.Context, generation string, index int) er
 	if err != nil {
 		return err
 	} else if _, err := tx.ExecContext(ctx, `SELECT COUNT(1) FROM _litestream_seq;`); err != nil {
-		tx.Rollback()
+		_ = tx.Rollback()
 		return err
 	}
-	defer tx.Rollback()
+	defer func() { _ = tx.Rollback() }()
 
 	// Open database file handle.
 	f, err := os.Open(r.db.Path())
@@ -681,6 +681,7 @@ func (r *Replica) findBucketRegion(ctx context.Context, bucket string) (string,
 	return "us-east-1", nil
 }
 
+// Sync replays data from the shadow WAL and uploads it to S3.
 func (r *Replica) Sync(ctx context.Context) (err error) {
 	// Clear last position if if an error occurs during sync.
 	defer func() {
@@ -1012,40 +1013,6 @@ func (r *Replica) deleteGenerationBefore(ctx context.Context, generation string,
 	return nil
 }
 
-type multiReadCloser struct {
-	readers []io.ReadCloser
-}
-
-func (mr *multiReadCloser) Read(p []byte) (n int, err error) {
-	for len(mr.readers) > 0 {
-		n, err = mr.readers[0].Read(p)
-		if err == io.EOF {
-			if e := mr.readers[0].Close(); e != nil {
-				return n, e
-			}
-			mr.readers[0] = nil
-			mr.readers = mr.readers[1:]
-		}
-
-		if n > 0 || err != io.EOF {
-			if err == io.EOF && len(mr.readers) > 0 {
-				err = nil
-			}
-			return
-		}
-	}
-	return 0, io.EOF
-}
-
-func (mr *multiReadCloser) Close() (err error) {
-	for _, r := range mr.readers {
-		if e := r.Close(); e != nil && err == nil {
-			err = e
-		}
-	}
-	return err
-}
-
 // S3 metrics.
 var (
 	operationTotalCounterVec = promauto.NewCounterVec(prometheus.CounterOpts{