I should have changed the subject to RFC. This patch hasn't actually been merged into Facter.
--
Jacob Helwig
On Tue, 12 Apr 2011 14:36:43 -0700, Jacob Helwig wrote:
>
> Instead of always grabbing the full set of facts and only grabbing
> those we're interested in, we attempt to look up every fact by the
> "normal" means of "fact name == containing file name", and only fall
> back to loading all of the facts if this fails to find any of the
> facts we're looking for.
>
> Paired-with: Max Martin <m...@puppetlabs.com>
> Signed-off-by: Jacob Helwig <ja...@puppetlabs.com>
> ---
>
> Local-branch: tickets/master/7039-multiple-facts-same-file
>
> Here's the proposed patch to potentially ease the overhead when asking
> for specific facts. The concern I have is that I didn't see any
> caching of fact values, which would mean potentially re-evaluating the
> facts that we'd already found in order to get a few that were missed
> because of mis-matches between the fact name, and the file name that
> contains it.
>
> It seems like the options are:
> * Always evaluate all facts once.
>
> * Potentially evaluate some facts twice, if we were unable to find
> all facts by name.
>
> I'm reluctant to add caching of fact values into Facter, given where I
> suspect this would need to be added, and that Puppet uses it as a
> library on the agent side (this seems like it would require changes on
> the agent side for cache invalidation).
>
> lib/facter/application.rb | 16 +++++++++++-----
> 1 files changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/lib/facter/application.rb b/lib/facter/application.rb
> index bd68149..9b0ba03 100644
> --- a/lib/facter/application.rb
> +++ b/lib/facter/application.rb
> @@ -10,12 +10,8 @@ module Facter
> names = argv
>
> # Create the facts hash that is printed to standard out.
> - # Pre-load all of the facts, since we can have multiple facts
> - # per file, and since we can't know ahead of time which file a
> - # fact will be in, we'll need to load every file.
> - facts = Facter.to_hash
> + facts = {}
> unless names.empty?
> - facts = {}
> names.each do |name|
> begin
> facts[name] = Facter.value(name)
> @@ -26,6 +22,16 @@ module Facter
> end
> end
>
> + # If names is empty, then we want all of the facts. If all of
> + # the asked for names aren't in the facts hash, then it's likely
> + # that we were asked for a fact that doesn't match the filename
> + # it's stored in, so the autoloader couldn't find it. In this
> + # case we just need to load all of the facts, since we have no
> + # way of figuring out which file it might be in.
> + if names.empty? || !names.all? { |n| facts[n] }
> + facts = Facter.to_hash
> + end
> +
> # Print the facts as YAML and exit
> if options[:yaml]
> require 'yaml'
> --
> 1.7.4.3
>
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