Expose Error Status To Caller

[zhixinwen]

Motivation

We were seeing a high rate Missing request message error on server side, but we do not know what exactly was going on. I think the error message may be hidden away in poll_data. I am not sure why tonic choose to drop the error message instead of returning it to the user. Can people familiar with the code explain why it was done in the current way?

Solution

return the error to users, so the error is more meaningful