code review 5486078: net: RFC: API proposal for DialPlan

net: RFC: API proposal for DialPlan

This is an API proposal that Russ and I sketched out
awhile back and recently dusted off.

Let's discuss the API before any implementation.

Issue 240

[bradfitz, 2011-12-14 23:14:07]

Hello golang-dev@googlegroups.com (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg

[dsymonds, 2011-12-14 23:47:08]

Can you describe what DialPlan/DialAttempt are for? When would I use
them? Is it meant to be some kind of multi-address auto-failover
dialing mechanism?


Dave.

[crawshaw1, 2011-12-15 04:26:51]

On Wed, Dec 14, 2011 at 3:14 PM,  <bradfitz@golang.org> wrote:
> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev@googlegroups.com (cc: golang-dev@googlegroups.com),
>
> I'd like you to review this change to
> https://go.googlecode.com/hg
>
>
> Description:
> net: RFC: API proposal for DialPlan
>
> This is an API proposal that Russ and I sketched out
> awhile back and recently dusted off.
>
> Let's discuss the API before any implementation.
>
> Issue 240
>
> Please review this at http://codereview.appspot.com/5486078/
>
> Affected files:
>  M src/pkg/net/dial.go
>
>
> Index: src/pkg/net/dial.go
> ===================================================================
> --- a/src/pkg/net/dial.go
> +++ b/src/pkg/net/dial.go
> @@ -4,6 +4,44 @@
>
>  package net
>
> +import (
> +       "time"
> +)
> +
> +// A DialPlan represents the strategy for connecting to a remote
> +// address.
> +type DialPlan struct {
> +       // Attempts lists
> +       Attempts []DialAttempt
> +}
> +
> +// A DialAttempt describes one attempt of a DialPlan.
> +type DialAttempt struct {
> +       // Remote is the destination to connect to.
> +       Remote Addr
> +
> +       // Local optionally specifies a local address to bind to.
> +       Local Addr
> +
> +       // Timeout, if non-zero, specifies the maximum amount
> +       // of time to wait for the connection to complete.
> +       Timeout time.Duration
> +
> +       // SoftTimeout, if non-zero, specifies the amount of
> +       // time to wait for this attempt to complete before
> +       // starting the next attempt and racing them.
> +       // See http://tools.ietf.org/html/draft-ietf-v6ops-happy-eyeballs-06
> +       SoftTimeout time.Duration
> +}

If I have multiple targets for an RPC, I want to keep dialing until
the RPC completes. This API only gets to the starting line.

> +
> +func (p *DialPlan) Dial() (Conn, error) {
> +       panic("TODO")
> +}
> +
> +func NewDialPlan(net, addr string) *DialPlan {
> +       panic("TODO")
> +}
> +
>  func resolveNetAddr(op, net, addr string) (a Addr, err error) {
>        if addr == "" {
>                return nil, &OpError{op, net, nil, errMissingAddress}
> @@ -65,6 +103,12 @@
>        return
>  }
>
> +// DialTimeout is like Dial, but returns ErrTimeout after timeout if a
> +// connection isn’t established.
> +func DialTimeout(net, addr string, timeout time.Duration) (c Conn, err
> error) {
> +       panic("TODO")
> +}
> +
>  // Listen announces on the local network address laddr.
>  // The network string net must be a stream-oriented
>  // network: "tcp", "tcp4", "tcp6", or "unix", or "unixpacket".
>
>

[rsc, 2011-12-15 16:45:40]

On Wed, Dec 14, 2011 at 23:26, David Crawshaw <crawshaw@google.com> wrote:
> If I have multiple targets for an RPC, I want to keep dialing until
> the RPC completes. This API only gets to the starting line.

I think that's debatable.  You want to find a server that
will take the RPC.  Whether you want to have multiple
servers working on your RPC racing to be the one who
gets done first is a separate issue.  In any event, that's
not what this CL is or needs to be about.  This is just
about trying to connect.

Russ