[erlang-questions] problem with global registration

[Ulf Wiger (TN/EAB)]

Where does your global server 'util' start?

When you call debugctrl() using the -run argument,
the call will be dispatched pretty early.

Chances are your globally registered process hasn't
had time to start yet.

BR,
Ulf W 

> -----Original Message-----
> From: erlang-questions-bounces@REDACTED 
> [mailto:erlang-questions-bounces@REDACTED] On Behalf Of 
> Garry Hodgson
> Sent: den 7 november 2006 19:54
> To: Erlang
> Subject: [erlang-questions] problem with global registration
> 
> i'm having some trouble with the global registration that's 
> implied by passing { global, ?MODULE } to the 
> gen_server:start that i call in a module's start() routine.  
> i want to centralize logging, and be able to enable/disable 
> log levels on the fly for debug purposes.  
> 
> specifically, i want to run my server the usual way, and then 
> use the "-run" arg to erl to run another erlang program to 
> disable logging.  so i use:
> 
>     erl -sname debug -setcookie keebler -run master debugctrl on
> 
> the function this invokes is:
> 
>     debugctrl( [ OnOff ] ) ->
>         case OnOff of
>             "on" ->
>                 util:enable( debug );
>             "off" ->
>                 util:disable( debug )
>         end,
>         halt().
> 
> the util:enable() function that this calls is:
> 
>     enable( Log ) ->
>         gen_server:call( { global, util }, { enable, Log }, 10000 ).
> 
> 
> when i run the control program, it fails, reporting the following:
> 
>     {"init terminating in do_boot",
>         
> {noproc,{gen_server,call,[{global,util},{enable,debug},10000]}}}
> 
> if i run my server in the erlang shell, then i can run 
> "util:enable( debug)."
> and it works fine.  of course, that's running in the same node.
> 
> the util process is started using { global, util }.
> my understanding is that this would globally register it.
> all the cookies match.  it's running on the same machine 
> (although i'll need to be able to do the same thing from 
> other machines).  this application is not being run via otp 
> proper (i.e. the supervisor/app/release/etc stuff).
> it's an older app that i'm slowly converting, using 
> gen_server whenever i need to add a new process.
> 
> so, anyone want to tell me what detail i've foolishly overlooked?
> or whether i'm just completely off base.  suggestions for a 
> better approach are welcome, as well.
> 
> thanks
> 
> ----
> Garry Hodgson, Senior Software Geek, AT&T CSO
> 
> But I'm not giving in an inch to fear
> 'Cause I promised myself this year
> I feel like I owe it...to someone.
> 
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