Re: [PATCH v5 0/9] Fixes for early logging/prints and related cleanups

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Jun 24, 2024 at 11:45:32AM +0200, Stefano Brivio wrote:
> On Mon, 24 Jun 2024 15:32:20 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > On Fri, Jun 21, 2024 at 11:33:55AM +0200, Stefano Brivio wrote:
> > > On Fri, 21 Jun 2024 11:17:34 +1000
> > > David Gibson <david@gibson.dropbear.id.au> wrote:
> > >   
> > > > On Thu, Jun 20, 2024 at 06:15:09PM +0200, Stefano Brivio wrote:  
> > > > > The most apparent issue fixed by this series is the one from 4/6: with
> > > > > a log file configured, we wouldn't print to standard error anymore,
> > > > > during initialisation, which means that users such as libvirt lost
> > > > > the ability to report meaningful error messages that occurred during
> > > > > initialisation, in that case.
> > > > > 
> > > > > v5:
> > > > > - in 4/8, rename the new flag once more to 'log_runtime': we don't
> > > > >   want to log to standard error if we're running in foreground, a
> > > > >   log file is given, and initialisation is done, otherwise debugging
> > > > >   pasta when it spawns its own shell becomes rather impractical    
> > > > 
> > > > Ah.. right.  See, I still think the semantics of always printing to
> > > > stderr when foreground make more sense, but I guess I do see the point
> > > > that having pasta messages appear in your pasta-spawned shell is ugly.
> > > > 
> > > > My preferred approach for that would to keep the basic semantics that
> > > > we always log to stderr when foreground, but when we're spawning a
> > > > pasta shell we default to 'quiet' log level.  That way if you really
> > > > do want messages to stderr along with your shell/command (which I
> > > > sometimes do), you can get that by using --debug or whatever.  
> > > 
> > > That's already the default, see pasta_start_ns():
> > > 
> > > 	if (!c->debug)
> > > 		c->quiet = 1;
> > > 
> > > the problem is that if you want to debug something, and use a pasta
> > > shell (which is the most indicated way to debug something in most
> > > cases, I would say), you would usually pass --debug and a log file.  
> > 
> > Oh... good point.
> > 
> > > Before and after this series (v5, but not v4), if you pass a log file,
> > > that debug output stays in the log file.
> > > 
> > > If you don't give a log file, debug information will printed to stderr
> > > as usual.  
> > 
> > I understand the choice in the short term, but this still doesn't feel
> > quite right to me.
> > 
> > I'm wondering if we should treat spawning a a pasta command as though
> > we're going into the background.  It's not in the Unix technical
> > sense, but it is going to the background in the loose sense that pasta
> > is no longer the thing that the user is primarily looking at on this
> > terminal.
> > 
> > But then, it would be nice to have a way to force output to stderr
> > even with a pasta command - I find that pretty useful when debugging a
> > specific problem, particularly when using a specific command rather
> > than a shell.  Maybe we could allow "-l -" or "-l stderr" or something
> > with a special meaning?
> 
> But that's already the case if you give --debug (or --trace) but no log
> file, isn't that enough?

It's the case now, but wouldn't be if we treated spawning a pasta
shell like going into the background, although that approach seems
more sensible to to me in other ways.

Eh, I can't quickly see a better way than what you have now, so never
mind.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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