[tarantool-patches] [PATCH 1/3] netbox: allow to create a netbox connection from existing socket
Konstantin Osipov
kostja at tarantool.org
Tue Mar 27 00:55:49 MSK 2018
* v.shpilevoy at tarantool.org <v.shpilevoy at tarantool.org> [18/03/22 22:54]:
> > 22 марта 2018 г., в 22:33, Konstantin Osipov <kostja at tarantool.org> написал(а):
> >
> > * Vladislav Shpilevoy <v.shpilevoy at tarantool.org <mailto:v.shpilevoy at tarantool.org>> [18/03/22 22:18]:
> >
> > The patch generally looks good to me, I can only nitpick on new
> > things.
> >
> > How about renaming do_connect to connect_impl and wrap_connect to
> > wrap_socket or simply wrap, or maybe bless or imbue?
>
> Ok.
>
> >
> >> + if existing_connection then
> >> + connection = existing_connection
> >> + existing_connection = nil
> >
> > Why is it necessary to set it to nil?
>
> On reconnect it will call protocol_sm again, and it must no get
> old existing_connection again.
This code is a mess and you make it even more messy.
What frustrates me most is that it's a trivial refactoring and
you prefer explaining why a fix is impossible rather than making
a good fix.
You *can* change the responsibilities of all of these functions so
that everything works nicely without extra branches and having to
pass existing_connection through several layers of calls.
> >
> >> + assert(greeting)
> >> + assert(greeting.protocol ~= 'Lua console')
> >
> > Please keep in mind that in Lua there are no asserts - it's a
> > runtime check.
> kk
> Ok.
>
> >> +
> >> +local function wrap_socket(connection, greeting, url, opts)
> >> + if connection == nil or type(greeting) ~= 'table' then
> >> + error('Usage: netbox.wrap_socket(socket, greeting, [opts])')
> >> + end
> >> + if greeting.protocol == 'Lua console' then
> >> + error('Can not wrap console socket')
> >> + end
> >> + opts = opts or {}
> >> + if not opts.user and not opts.password then
> >> + opts.user, opts.password = url.login, url.password
> >> + end
> >> + return do_connect(url.host, url.service, opts, connection, greeting)
> >> +end
> >
> > Looks like you should make the next step, i.e. take the piece of
> > do_connect which establishes a connection and move it to
> > connect(), and then you can the remains of do_connect into wrap()
> > and call wrap() connect().
> >
> > Did you try to do it? Had any trouble?
>
> Connection establishment must be in connect inside
> create_transport, because even if an existing socket was
> wrapped, it still can have opts.reconnect_after option and the
> following scenario:
> socket = ...
> con = netbox.wrap_socket(socket, ..., {reconnect_after = ...})
> --
> -- use connection ...
> --
>
> Suppose it is broken due to error. Then netbox will try to
> establish a new connection after 'reconnect_after' seconds.
You can leave reconnect in protocol_sm, but you can make sure
protocol_sm is never called without an existing connection.
You can make the first connect directly in create_transport(),
or better yet, as I first suggested, outside, removing the need
for connect_impl().
--
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.org - www.twitter.com/kostja_osipov
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