can we fix error return when connection closed [close by server or server(or proxy) restart]

[hengkiang]

sometimes when developer forget to call SetConnMaxLifetime(sql api), or when developer use mysql with a proxy server, and the proxy server restart.

at these times, the connection is closed, the api return ErrInvalidConn. but this can not distinguish the error is connection is already closed , or other unexpect error。
so, when receive this error(ErrInvalidConn), developer can not decide appropriate retry is appropriate。

so, how about to return io.EOF when receive io.EOF . such as :

and return driver.ErrBadConn when read the packet length, such as:

if return driver.ErrBadConn, the go sql api will retry again to fix closed connection, this can work gracefull

[shogo82148]

Did you try #934 ?
It may resolve your issue.

[hengkiang]

thank you, let me have a try

[hengkiang]

@shogo82148
I have try with master, and update go with version 1.12.8, but it donnot work.
I add log to print the reset value.

when I suddenly restart the proxy, the reset value is not true, and it still print "unexpected EOF"

[methane]

if return driver.ErrBadConn, the go sql api will retry again to fix closed connection, this can work gracefull

It is not an option. After we send any query, the query may be executed even if we received EOF.
You shouldn't restart proxy server while application is online.