Debugging "Failed to process pack"

jamesnvc · July 11, 2021, 1:43pm

This topic has come up a few times before (here and here) but it looks like there were no replies then, so hopefully third time will be the charm.

Is there any way to debug why a pack (e.g.) on the SWI-Prolog directory shows the “failed to process pack” error message? The pack installs fine, locally everything seems okay, the pldoc displays properly, so I’m not exactly sure where else to look.

swi · July 11, 2021, 5:49pm

The error is thrown by the prolog website, when it calls pack_file_hierarchy//1, the error is thrown here:

github.com

SWI-Prolog/plweb/blob/eb3ad829e48c4183ae53cefb43e21c3c2565e989/pack.pl#L927

    
      
          	{ \+ pack(Pack) }, !,
          	html(p(class(warning),
          	       'Sorry, I know nothing about a pack named "~w"'-[Pack])).
          pack_info(Pack) -->
          	pack_info_table(Pack),
          	pack_reviews(Pack),
          	pack_file_table(Pack),
          	( pack_readme(Pack) -> [] ; [] ),
          	(   pack_file_hierarchy(Pack)
          	->  []
          	;   html(p(class(warning), 'Failed to process pack'))
          	).
          
          
%%	pack_info_table(+Pack)// is det.
          %
          %	Provide basic information on the package
          
          
pack_info_table(Pack) -->
          	{ pack_latest_version(Pack, SHA1, Version, _Older),
          	  prolog_pack:atom_version(VersionA, Version),
          	  sha1_title(SHA1, Title),

This may help you track down things a little further.

pack_file_hierarcy//1 is here:

github.com

SWI-Prolog/plweb/blob/4f38fac069718dc88b68fa2671aa8bf303ed691e/pack_info.pl#L175

    
      
          ensure_xref_pack(Pack) :-
          	xref_pack(Pack),
          	get_time(Time),
          	asserta(xreffed_pack(Pack, Time)).
          
          

          
		 /*******************************
          		 *	     VISUALS		*
          		 *******************************/
          
          
%%	pack_file_hierarchy(+Pack)// is det.
          %
          %	Create a =ul= for all files that   appear  in the pack. Maybe we
          %	should consider a tree-styled nested =ul=?
          
          
pack_file_hierarchy(Pack) -->
          	html(h2(class(wiki), 'Contents of pack "~w"'-[Pack])),
          	{ mirror_pack(Pack),
          	  pack_archive(Pack, _Hash, Archive),
          	  ensure_xref_pack(Archive),
          	  findall(File, pack_file(Pack, File, _Size, _XrefID), Files),

jamesnvc · July 11, 2021, 6:22pm

Oh, good call to check the website source! That will certainly give me a place to check, I’ll investigate that further

jamesnvc · July 11, 2021, 7:02pm

Hm, after futzing around a little to get the pack installed locally, pack_file_hierarchy//1 succeeds & shows the info on my end. Perhaps something to do with a previous version causing bad data for the pack to be saved?

jan · July 12, 2021, 6:51am

Which pack are we talking about?

jamesnvc · July 12, 2021, 12:30pm

I’m specifically trying to figure out why my new tailwind_pl pack is showing the error message, but it seems like it’s something that’s come up before as well, so I’d be interested to see a general solution.

jan · July 12, 2021, 3:57pm

It seems to be fine now, no? Did this get fixed “by magic”, or did you do something? It is just a generic error. Without a reproducible case we can debug it will get hard.

jamesnvc · July 12, 2021, 4:27pm

Oh, indeed. Strange, even this morning when I replied I checked and it was still showing the error, but it is good now. I guess something was cached; I haven’t changed anything since yesterday.

jan · July 13, 2021, 6:27am

The CDN network caches for one hour. You can contact one of the backends directly at e.g., eu.swi-prolog.org.

jamesnvc · July 13, 2021, 5:03pm

Hm, I don’t know if it was simply the HTML being cached, since I did see the latest version displayed on the page; not to mention it was in that state for much longer than an hour. Is there any sort of backround job on the server that only periodically updates the pack pages?