When the buffered io writer is used, and some error occur, how can I perform the retry? For example, I've written 4096B using Write() and an error occur when the bufwriter automatically flushes the data. Then I want to retry writing the 4096B, how I can do it? It seems I must keep a 4096B buffer myself to perform the retrying. Othersize I'm not able to get the data failed to be flushed. Any suggestions?
You'll have to use a custom io.Writer that keeps a copy of all data, so that it can be re-used in case of a retry.
This functionality is not part of the standard library, but shouldn't be hard to implement yourself.
When bufio.Writer fails on a Write(..) it will return the amount of bytes written (n) to the buffer the reason why (err).
What you could do is the following. (Note I haven't yet tried this so it may be a little wrong and could use some cleaning up)
func writeSomething(data []byte, w *bufio.Writer) (err error) {
var pos, written int = 0
for pos != len(data) {
written, err = w.Write(data[pos:])
if err != nil {
if err == io.ErrShortWrite {
pos += written // Write was shot. Update pos and keep going
continue
} else netErr, ok := err.(net.Error); ok && netErr.Temporary() {
continue // Temporary error, don't update pos so it will try writing again
} else {
break // Unrecoverable error, bail
}
} else {
pos += written
}
}
return nil
}