Make ExchangeWithConnContext public

[andrew-d]

If we want to use a custom mechanism of obtaining a Conn that doesn't match the net.Dialer type, but retain the timeout behaviour from ExchangeContext, there was previously no way to accomplish this.

This PR makes the underlying ExchangeWithConnContext function public, which allows this behaviour.

Now that #1454 is merged, there is no longer any interaction between the context provided and the singleflight behaviour, so I removed the comment from ExchangeWithConn.

[andrew-d]

@miekg @tmthrgd gentle ping on this; anything I can do to help move this forward? Happy to e.g. write additional tests.

[miekg]

If we want to use a custom mechanism of obtaining a Conn that doesn't match the net.Dialer type, but retain the timeout behaviour from ExchangeContext, there was previously no way to accomplish this.

I don't understand... you mean doesn't match the net.Conn interface or some such? As exchangeWithConnContext has the identical paramaters (apart from the context) I don't see how this would help

[andrew-d]

If we want to use a custom mechanism of obtaining a Conn that doesn't match the net.Dialer type, but retain the timeout behaviour from ExchangeContext, there was previously no way to accomplish this.

I don't understand... you mean doesn't match the net.Conn interface or some such? As exchangeWithConnContext has the identical paramaters (apart from the context) I don't see how this would help

Concretely: if I need to do something to obtain a *dns.Conn other than using a *net.Dialer (through Client.Dialer), there's no way to both do that and add a timeout to the request. I can do something like:

netConn, err := myDialFunc(/* args */)
// check err
conn := &dns.Conn{
	Conn: netConn,
}

var c dns.Client
resp, _, err := c.ExchangeWithConn(msg, conn)

However, there's no way to add a timeout to the ExchangeWithConn function. ExchangeContext doesn't let me provide a *dns.Conn, and the Dialer field of Client is of concrete type *net.Dialer so I can't override it with my custom dial logic.

Exposing ExchangeWithConnContext would allow me to pass a context.Context with an appropriate deadline and thus add a timeout to the query.

[miekg]

Ah I see. Also for symmetry it would be nice to have both those *Context function to be public. Cheers

…

On Sun, 18 Jun 2023, 01:51 Andrew Dunham, ***@***.***> wrote: If we want to use a custom mechanism of obtaining a Conn that doesn't match the net.Dialer type, but retain the timeout behaviour from ExchangeContext, there was previously no way to accomplish this. I don't understand... you mean doesn't match the net.Conn interface or some such? As exchangeWithConnContext has the identical paramaters (apart from the context) I don't see how this would help Concretely: if I need to do something to obtain a *dns.Conn other than using a *net.Dialer (through Client.Dialer), there's no way to both do that and add a timeout to the request. I can do something like: netConn, err := myDialFunc(/* args */)// check errconn := &dns.Conn{ Conn: netConn, } var c dns.Clientresp, _, err := c.ExchangeWithConn(msg, conn) However, there's no way to add a timeout to the ExchangeWithConn function. ExchangeContext doesn't let me provide a *dns.Conn, and the Dialer field of Client is of concrete type *net.Dialer so I can't override it with my custom dial logic. Exposing ExchangeWithConnContext would allow me to pass a context.Context with an appropriate deadline and thus add a timeout to the query. — Reply to this email directly, view it on GitHub <#1459 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACWIW4MJEL2A5CYUSJAOB3XLY7JVANCNFSM6AAAAAAX5HF54U> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[andrew-d]

Thank you!