Bug#385976: strange (and annoying) delay on startup

[Loïc Minier]

reassign 385976 libice6
retitle  385976 SocketUNIXConnect shouldn't return TRANS_TRY_CONNECT_AGAIN when the socket file doesn't exist
severity 385976 minor
stop

        Hi,

On Sun, Sep 10, 2006, Robert Millan wrote:
> Interesting... it turns out my shell's $SESSION_MANAGER is pointing to
> a socket that belonged to an older X session.  As to why this happens,
> my shell was spawned by a screen session that's much older than my X
> server (when I have to restart X I just detach from screen, and later
> reattach).
> 
> However, that doesn't explain the delay.  You can tell the socket is
> not there inmediately.

 This is presumably a bug in libICE (Inter-Client Exchange library), or
 even in xtrans.
   When libICE fails connecting (in ConnectToPeer), and gets
 TRANS_TRY_CONNECT_AGAIN, it will retry the connection 5 times with a 1
 second sleep() between retries.

 The "local" Xtrans transport can either be implemented in Xtranslcl
 which never returns TRANS_TRY_CONNECT_AGAIN, but returns
 TRANS_CONNECT_FAILED, or in Xtranssock.  Hence, here it's obviously in
 Xtranssock that the code is.

 Looking at the code, when connect() fails with ENOENT ("No such file or
 directory"), SocketUNIXConnect returns TRANS_TRY_CONNECT_AGAIN, and a
 comment says (Xtranssock.c:2048):
             * If the error was ENOENT, the server may be starting up
             * and we should try again.
 (This is the typical error code you get when the UNIX socket file
 doesn't exist.)


 I'm reassigning to libice6.  From what I read, the connection string
 seems correct, so it should fail fast when it notices the socket is
 missing; perhaps another workaround can be found for slow starting
 servers?

 Or perhaps the semantics should be extended to permit both behaviors,
 for example programs such as "gnome-session" would typically want to
 wait for the socket, while other clients, such as clients launched by
 gnome-session or later during the session by the user, might not
 consider that the "server is starting up".


   Bye,

PS: note to self:
 Connection is made via TRANS(Connect), with the literal connection
 string from the env, in my case local/bee:/tmp/.ICE-unix/00000, and is
 parsed in TRANS(ParseAddress).  You can check this by using:
    SESSION_MANAGER=local/bee:/tmp/.ICE-unix/00000 gcalctool
    SESSION_MANAGER=local/:0 gcalctool
    SESSION_MANAGER=/:0 gcalctool
-- 
Loïc Minier <lool at dooz.org>