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Re: Bash-completion with triggers



Hi,

On Thu, 07 Apr 2011, David Paleino wrote:
> Hello everybody,
> I've implemented a new revision of bash-completion, which uses debtriggers(5)
> to load only relevant completions, and symlink them when something
> touches /usr/bin/, /usr/games/, /usr/sbin/, /sbin/, /bin/, and so on.
> 
> For this to work, the completions have been moved out from /etc/ -- they would
> be in /usr/share/bash-completion/completions/, but /etc/bash_completion.d/ is
> being kept not to break tons of other packages installing files there.
> 
> However, I'm writing to get comments about the triggers issue. When a package
> installs an executable in one of the above directories, bash-completion's
> postinst removed all symlinks in /etc/bash_completion.d/triggered/, and
> re-creates them. The speed of such operation varies greatly depending on the
> installed packages -- on my system, it takes about 10s -- but the shell loading
> seems much faster too.
> 
> Is there any objection to bash-completion using triggers to "watch" the
> aforementioned directories?

I feel uneasy about this. It means the trigger is going to be activated
for any package installation and all packages are going to be put in
triggers-awaited state.

The trigger is going to happen very often (like the man-db one) and
with a 10s impact it's very noticable...

Even if we change apt to actually keep trigger processing to the end of
the APT run, I fear that the dependency resolution logic is going to
force the trigger to run sooner and more often because a package
in trigger-awaited status does not satisfy the dependencies.

If file triggers could also specify the --no-await option that
dpkg-triggers supports, things might be different.

But in the current state, I think it's a bad idea to use file triggers
in your case.

You'd better use some apt hook to do the task you envision. A file
trigger that is activated for a majority of package installation is
probably better dealt with such a solution.

Cheers,
-- 
Raphaël Hertzog ◈ Debian Developer

Follow my Debian News ▶ http://RaphaelHertzog.com (English)
                      ▶ http://RaphaelHertzog.fr (Français)


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