Re: [Nbd] About error management

[Wouter Verhelst <w@...112...>]

You really know how to dig up the worst warts in nbd, don't you? ;-)

On Fri, Dec 28, 2012 at 04:34:51PM +0200, Tuomas Jorma Juhani Räsänen wrote:
> Hi
> 
> Now that I've started to work on generalizing the dynamic
> reconfiguration hack, I bumped into the quite complex or at least
> unnecessarily complex error mangement scheme currently used in
> nbd-server.c. There seems to be several different error reporting
> styles: fprintf(), msgX(), g_warning(), perror(). Maybe we could try
> to uniform this somehow?

Yes, that code is pretty hary. It was already there when I first
inherited the nbd tools; I just never got around to cleaning it up.

> But the real problem is, that in many places, error reporting and
> handling is tightly coupled and buried inside utility functions. Uses
> of err() or perror() followed by exit() are good examples. I do
> realize that there probably hasn't been a real need for separating
> reporting from handling earlier, but now there is. To exploit the
> existing code base, error handling (i.e. the decisions to what to make
> in case of an error) needs to be separeted from error reporting:
> calling a function which might call exit() in the middle of a
> reconfiguration process is obviously going to cause troubles sooner or
> later.

True.

> My suggestion is that because we are already depending on libglib and
> using it's error reporting framework in few places, we should try to
> use the same mechanism everywhere. In other words, we should pass
> GError** to functions requiring an error reporting mechanism and then
> make the error handling decisions in the caller.
> 
> Thoughts?

I've been planning on generalising error handling in precisely that way;
in fact, there is already one place where I do use a GError** parameter.
It just isn't being done consistently yet, because it would be a massive
undertaking to refactor the code in that way.

If you were to do that, I'd owe you a beer. Seriously.

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