Re: [9fans] ORCLOSE

["Russ Cox" <rsc@swtch.com>]

> that's often not a reliable sign.  networks go down.  dhcp and
> ppp may reassign addresses.

Sorry.  9P does not address such concerns.  There is no notion
of re-establishing a connection.  If your connection is dropped,
your ORCLOSE files get removed, all your other files get closed
(including lock files, making them available for use by others).

If you are concerned about keeping a single 9P session across
multiple network instances, you can use a 9P filter like aan or
recover.  Aan just sits on top of any network connection, allowing
special clients and servers to reconnect and pick up where they
left off.  Neither side knows that the connection got lost.

Recover is a client-only solution.  A program runs on the client
that keeps track of the fids the client is using.  If the connection
is lost, then recover redials and reestablishes the fid state as
needed.  It handles ORCLOSE specially: it strips that bit out of the
open mode and turns Tclunks on previously-ORCLOSE fids into
Tremoves.  It also refuses to reopen exclusive-use files.

Recover is not in the distribution yet.  I wrote it for the old 9P and
revised it for 9P2000 but never quite finished it.  Gorka finished it
and tested it last summer but I haven't gotten around to putting
it in.  So for now it's ozinferno^Wvapor-ware.  Sorry.

Russ