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-rw-r--r--doc/bugs/Slow_Filecheck_attachments___34__snails_it_all__34__/discussion.mdwn114
1 files changed, 114 insertions, 0 deletions
diff --git a/doc/bugs/Slow_Filecheck_attachments___34__snails_it_all__34__/discussion.mdwn b/doc/bugs/Slow_Filecheck_attachments___34__snails_it_all__34__/discussion.mdwn
index 6684d79ee..d0582cbff 100644
--- a/doc/bugs/Slow_Filecheck_attachments___34__snails_it_all__34__/discussion.mdwn
+++ b/doc/bugs/Slow_Filecheck_attachments___34__snails_it_all__34__/discussion.mdwn
@@ -1,3 +1,4 @@
+##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.
@@ -16,3 +17,116 @@ sub import {
}
</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