// ctx will be canceled on failure
func (c *Collector) markItem(ctx *context.Context, it Item, isRoot bool) error {
if !isRoot {
marked, err := c.Marker.IsMarked(it)
if err != nil {
return err
}
if marked {
return nil
}
}
if err := c.Marker.Mark(it); err != nil {
return err
}
ch := make(chan Item, buffered)
var grp syncutil.Group
grp.Go(func() error {
return c.ItemEnumerator.EnumerateItem(ctx, it, ch)
})
grp.Go(func() error {
for it := range ch {
if err := c.markItem(ctx, it, false); err != nil {
return err
}
}
return nil
})
if err := grp.Err(); err != nil {
ctx.Cancel()
return err
}
return nil
}