ikiwiki/doc/bugs/Slow_Filecheck_attachments_.../discussion.mdwn

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##Foreword :
Disabling of filecheck is not actually possible because btw it cause the attachment.pm to malfunction and
any of pagespec that could contain a *mimetype* condition.
attachment.pm imports "statically" filecheck so actually disabling it should be *interdicted* .
<pre>
sub import {
add_underlay("attachment");
add_underlay("javascript");
add_underlay("jquery");
hook(type => "getsetup", id => "attachment", call => \&getsetup);
hook(type => "checkconfig", id => "attachment", call => \&checkconfig);
hook(type => "formbuilder_setup", id => "attachment", call => \&formbuilder_setup);
hook(type => "formbuilder", id => "attachment", call => \&formbuilder, last => 1);
IkiWiki::loadplugin("filecheck");
}
</pre>
----
## How bad is it ?
So I tried on three pages to inline <tt>!mimetype(image/*)</tt> while I allowed attachment of <tt>mimetype(image/*)</tt>
My profiling tests in the bug report shows that most of the time is spend in the "Fallback using file" block code,
I tried to comment that block and see how it'll perform. Obviously this is much much faster ... but is the mimetype
discovered using only *File::MimeInfo* ?
Dumping some strings before return to STDERR, rebuilding . This is just a [[!toggle id="code-test" text="dumpdebug adding"]]
[[!toggleable id="code-test" text="""
<pre>
sub match_mimetype ($$;@) {
my $page=shift;
my $wanted=shift;
my %params=@_;
my $file=exists $params{file} ? $params{file} : IkiWiki::srcfile($IkiWiki::pagesources{$page});
if (! defined $file) {
return IkiWiki::ErrorReason->new("file does not exist");
}
# Get the mime type.
#
# First, try File::Mimeinfo. This is fast, but doesn't recognise
# all files.
eval q{use File::MimeInfo::Magic};
my $mimeinfo_ok=! $@;
my $mimetype;
print STDERR " --- match_mimetype (".$file.")\n";
if ($mimeinfo_ok) {
my $mimetype=File::MimeInfo::Magic::magic($file);
}
# Fall back to using file, which has a more complete
# magic database.
#if (! defined $mimetype) {
# open(my $file_h, "-|", "file", "-bi", $file);
# $mimetype=<$file_h>;
# chomp $mimetype;
# close $file_h;
#}
if (! defined $mimetype || $mimetype !~s /;.*//) {
# Fall back to default value.
$mimetype=File::MimeInfo::Magic::default($file)
if $mimeinfo_ok;
if (! defined $mimetype) {
$mimetype="unknown";
}
}
my $regexp=IkiWiki::glob2re($wanted);
if ($mimetype!~$regexp) {
print STDERR " xxx MIME unknown ($mimetype - $wanted - $regexp ) \n";
return IkiWiki::FailReason->new("file MIME type is $mimetype, not $wanted");
}
else {
print STDERR " vvv MIME found\n";
return IkiWiki::SuccessReason->new("file MIME type is $mimetype");
}
}
</pre>
"""]]
The results dump to stderr (or a file called... 'say *mime*) looks like this :
<pre>
--- match_mimetype (/usr/share/ikiwiki/attachment/ikiwiki/jquery.fileupload-ui.js)
xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$) )
--- match_mimetype (/usr/share/ikiwiki/locale/fr/directives/ikiwiki/directive/fortune.mdwn)
xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$) )
--- match_mimetype (/usr/share/ikiwiki/locale/fr/basewiki/shortcuts.mdwn)
xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$)
--- match_mimetype (/usr/share/ikiwiki/smiley/smileys/alert.png)
xxx MIME unknown (application/octet-stream - image/* - (?i-xsm:^image\/.*$) )
--- match_mimetype (/usr/share/ikiwiki/attachment/ikiwiki/images/ui-bg_flat_75_ffffff_40x100.png)
xxx MIME unknown (application/octet-stream - image/* - (?i-xsm:^image\/.*$)
</pre>
<tt>---</tt> prepend signals the file on analysis<br/>
<tt>xxx</tt> prepend signals a returns failure : mime is unknown, the match is a failure<br/>
<tt>vvv</tt> prepend signals a return success.<br/>
This is nasty-scary results ! Something missed me or this mime-filecheck is plain nuts ?
*Question 1* : How many files have been analysed : **3055** (yet on a tiny tiny wiki)
<pre>grep "^ --- " mime | wc -l
3055
</pre>
*Question 2* : How many time it fails : *all the time*
<pre>
grep "^ xxx " mime | wc -l
3055
</pre>
*Question 1bis* : Doh btw , how many files have been re-analysed ? ** 2835 ** OMG !!
<pre>grep "^ --- " mime | sort -u | wc -l
220
</pre>
## Conclusion
- Only the system command *file -bi* works. While it is **should** be easy on the cpu , it's also hard on the I/O -> VM :(
- Something nasty with the mime implementation and/or my system configuration -> Hints ? :D
- Need to cache during the rebuild : a same page needs not being rechecked for its mime while it's locked !
--mathdesc