英文:
How to get the data buffered in bufio.Writer in golang
问题
当使用缓冲IO写入器（buffered io writer）时，如果发生错误，我该如何进行重试呢？
例如，我使用Write()方法写入了4096字节的数据，当缓冲写入器自动刷新数据时发生了错误。然后我想要重试写入这4096字节的数据，我该如何做呢？
似乎我必须自己保留一个4096字节的缓冲区来进行重试。否则，我将无法获取未能成功刷新的数据。
有什么建议吗？
英文:
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?
答案1
得分: 1
你需要使用一个自定义的io.Writer，它可以保存所有的数据副本，以便在重试时可以重新使用。
这个功能不是标准库的一部分，但是自己实现应该不难。
英文:
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.
答案2
得分: 1
当bufio.Writer在Write(..)操作失败时，它会返回写入缓冲区的字节数(n)以及失败的原因(err)。
你可以尝试以下方法。（注意：我还没有尝试过，所以可能有一些错误，需要进行一些清理）
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 // 写入不完整。更新 pos 并继续循环
continue
} else if netErr, ok := err.(net.Error); ok && netErr.Temporary() {
continue // 临时错误，不更新 pos，以便再次尝试写入
} else {
break // 无法恢复的错误，退出循环
}
} else {
pos += written
}
}
return nil
}
希望对你有所帮助！
英文:
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
}
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