refactor net code to use transports, in rough accordance with libp2p

[whyrusleeping]

refactor as discussed with @jbenet. (with a couple extra methods on the interfaces)

This has the nice effect of removing go-multiaddr-net imports from a lot of places.

License: MIT
Signed-off-by: Jeromy jeromyj@gmail.com

[whyrusleeping]

@jbenet one question I still have is how to wire timeouts into the Dialer through this interface.

[jbenet]

@whyrusleeping probably extend it to have the same vars? not sure.

[whyrusleeping]

@jbenet but its an interface... Its going to have to be one of:

type Transport interface {
    Dialer(la ma.Multiaddr, opts ...[]DialOpts) (Dialer, error)
....
}

or

type Dialer interface {
    DialTimeout(a ma.Multiaddr, t time.Duration) (Conn, error)
...
}

[cryptix]

type Transport interface {
    Dialer(la ma.Multiaddr, opts ...DialOpts) (Dialer, error)
}

type DialOpts func(*Transport) error

func SetTimeout(t time.Duration) DialOpts {
    return func(tr *Transport) error {
    // setup timeout on tr
    }
}

seems more flexible to me.

[whyrusleeping]

@cryptix i'd like to be able to use the functional options, but in this case its non-trivial (and more trouble than its worth).

Each implementation of a transport dialer may want different options, and have different ways of setting them, so we cant nicely make it a method on the interface.

[cryptix]

Couldn't you type assert to other interface in SetTimeout like:

func SetTimeout(t time.Duration) DialOpts {
    return func(tr *Transport) error {

        switch v := tr.(type) {
        case ma.Timeouter:
            _ = v.SetTimeout(t)

        case net.Dialer:
            d := net.Dialer{Timeout: timeout}
            tr.UseDialer(d)
        }
    }
}

[daviddias]

@whyrusleeping #1937 (comment)

Can't it be one of the opts when you instantiate the Transport for the first time?

[whyrusleeping]

@diasdavid yeah... it could be. but then that makes it pretty difficult to change the settings later on if needed.

[daviddias]

is MeteredConn a 'Connection Upgrade' that dumps bandwidth metrics? This is really a great idea!

[whyrusleeping]

yeap!

[daviddias]

I want it the js stuff! :D

[jbenet]

@diasdavid just another transport :)

[whyrusleeping]

Once we merge this, rebase 0.4.0 and extract libp2p, i'm going to grab most of the actual 'networking' code from multiaddr-net and put it in the transport lib, leaving all of the multiaddr parsing/handling code there.

[jbenet]

Maybe just Listen to match go? not sure. we can always change it later.

[jbenet]

@whyrusleeping this LGTM! great, great changeset. Really happy with how this interface turned out.

only major thing to fix is:

• restore the old retErr behavior that does not stop the listen/setup method on Listen failure.

minor:

• maybe Transport.Listen instead of Transport.Listener ?
• maybe Swarm.setupInterfaces or just Swarm.setup ?

[whyrusleeping]

alright, we no longer fail out on swarm setup unless all listens fail.

[daviddias]

It got merged, wooo!