Re: [PATCH 00/18] Gitweb caching v8

John, could you please in the future Cc me?  I am interested in gitweb
output caching development.  Thanks in advance.

"John 'Warthog9' Hawley" [off-list ref] writes:

Afternoon everyone,

(Afternoon is like morning, right?)
 
This is the latest incarnation of gitweb w/ caching.  Per the general
consensus and requests from the recent GitTogether I'm re-submitting 
my patches.

Bunch of re-works in the code, and several requested features.  Sadly the
patch series has balloned as I've been adding things.  It was 3-4 patches,
it's now 18.  This is based on top of Jakub's v7.2 patch series, but
it should be more or less clean now.

Could you please rebase it on top of v7.2 version?  The v7.2 patch
series contained a few bugs that needs to be corrected.

As such there was a bunch of changes that I needed to do to Jakub's tree
which are indicated in the series.  Why did I do them up as separate things?
Mainly there's a bunch of history that's getting lost right now between
going back and forth, and I wanted to have clear patches to discuss
should further discussion be needed.

I guess that in the final submission (i.e. the one that is to be
merged in into git.git repository) those changes would be squashed in,
isn't it?

This still differs, by two patches, from whats in production on kernel.org.
It's missing the index page git:// link, and kernel.org and kernel.org also
has the forced version matching.  As a note I'll probably let this stew
another day or so on kernel.org and then I'll push it into the Fedora update
stream, as there's a couple of things in this patch series that would be 
good for them to have.

There was some discussion about git:// link in the past; nevertheless
this issue is independent on gitweb caching and can (and should) be
sent as a aeparate patch.

IIRC we agreed that because of backward compatibility forced versions
match is quite useless (in general)...

There is one additional script I've written that the Fedora folks are using,
and that might be useful to include, which is an 'offline' cache file generator.
It basically wraps gitweb.cgi and at the end moves the cache file into the right
place.  The Fedora folks were finding it took hours to generate their front
page, and that doing a background generation almost never completed (due to 
process death).  This was a simple way to handle that.  If people would like
I can add it in as an additional patch.

Are you detaching the background process?

It would be nice to have it as separate patch.

v8:
	- Reverting several changes from Jakub's change set that make no sense
                - is_cacheable changed to always return true - nothing special about
                  blame or blame_incremental as far as the caching engine is concerned

'blame_incremental' is just another version of 'blame' view.  I have
disabled it when caching is enabled in my rewrite (you instead disabled
caching for 'blame_incremental' in your v7 and mine v7.x) because I
couldn't get it to work together with caching.  Did you check that it
works?

Besides, withou "tee"-ing, i.e. printing output as it is captured,
cached 'blame_data' means that 'blame_incremental' is not incremental,
and therefore it vanishes its advantage over 'blame'.

In the case data is in cache, then 'blame_inremental' doesn't have
advantage over 'blame' either.

                - Reverted config file change "caching_enabled" back to "cache_enable" as this
                  config file option is already in the wild in production code, as are all
                  current gitweb-caching configuration variables.

[Explitive deleted.]  I dislike strongly this $cache_enable.  I think it
would be better for backward compatibility (should we keep backward
compatibility with out-of-tree patches?) to use the same mechanism as
provided in 

  [PATCHv6/RFC 22/24] gitweb: Support legacy options used by kernel.org caching engine
  http://thread.gmane.org/gmane.comp.version-control.git/163052/focus=163058
  http://repo.or.cz/w/git/jnareb-git.git/commitdiff/27ec67ad90ecd56ac3d05f6a9ea49b6faabf7d0a

in my rewrite.  Just set $caching_enabled to true if $cache_enable is
defined and true.

                - Reverted change to reset_output as
                        open STDOUT, ">&", \*STDOUT_REAL;
                  causes assertion failures:
                  Assertion !((((s->var)->sv_flags & (0x00004000|0x00008000)) == 0x00008000) && (((svtype)((s->var)->sv_flags & 0xff)) == SVt_PVGV || ((svtype)((s->var)->sv_flags & 0xff)) == SVt_PVLV)) failed: file "scalar.xs", line 49 at gitweb.cgi line 1221.
                  if we encounter an error *BEFORE* we've ever changed the output.

Which Perl version are you using?  Because I think you found error in Perl.
Well, at least I have not happen on this bug.

I have nothing againts using

  open STDOUT, ">&STDOUT_REAL";

though I really prefer that you used lexical filehandles, instead of
"globs" which are global variables.

The following works:

  open STDOUT, '>&', fileno($fh);

Note that fileno(Symbol::qualify_to_ref($fh)) might be needed...

        - Cleanups there were indirectly mentioned by Jakub
                - Elimination of anything even remotely looking like duplicate code
                        - Creation of isBinaryAction() and isFeedAction()

Could you please do not use mixedCase names?


First, that is what %actions_info from

  [PATCH 16/24] gitweb: Introduce %actions_info, gathering information about actions
  http://thread.gmane.org/gmane.comp.version-control.git/163052/focus=163038
  http://repo.or.cz/w/git/jnareb-git.git/commitdiff/305a10339b33d56b4a50708d71e8f42453c8cb1f

I have invented for.

Second, why 'isBinaryAction()'?  there isn't something inherently
different between binary (':raw') and text (':utf8') output, as I have
repeatedly said before.  See my rewrite: there is no special case for
binary output (or perhaps binary output as in the case of 'blob_plain'
action).

        - Adding in blacklist of "dumb" clients for purposes of downloading content
        - Added more explicit disablement of "Generating..." page

Good, I'll check this.

        - Added better error handling
                - Creation of .err file in the cache directory
                - Trap STDERR output into $output_err as this was spewing data prior
                  to any header information being sent

Why it is needed?  We capture output of "die" via CGI::Util::set_message,
and "warn" output is captured to web server logs... unless you explicitely
use "print STDERR <sth>" -- don't do that instead.

        - Added hidden field in footer for url & hash of url, which is extremely useful
          for debugging

Nice idea, I'll see it.  Can it be disabled (information leakage)?

-- 
Jakub Narebski
Poland
ShadeHawk on #git