urosm
/
ikiwiki
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

response

master
joey 2007-07-25 00:39:26 +00:00
parent 03a8c0d192
commit 2f3a4f6899
1 changed files with 44 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
doc/bugs/Buggy_dependency_graph.mdwn
View File

@ -34,3 +34,47 @@ I observed these problems (same *kind*, I didn't check in details) on
I can think about reducung the size of my wiki source and making it available online for analysis.
-- NicolasLimare
> As long as these dependencies don't grow over time (ie, when a page is
> edited and nothing changed that should add a dependency), I wouldn't
> worry about them. There are many things that can cause non-optimal
> dependencies to be recorded. For one thing, if you inline something, ikiwiki
> creates a dependency like:
>
> (PageSpec) or (file1 or file2 or file3 ...)
>
> Where fileN are all the files that the PageSpec currently matches. (This
> is ncessary to detect when a currently inlined file is deleted, and know
> the inlining page needs an update.) Now consider what it does if you have
> a single page with two inline statements, that inline the same set of
> stuff twice:
>
> ((PageSpec) or (file1 or file2 or file3 ...) or (PageSpec) or (file1 or file2 or file3 ...)
>
> Clearly non-optimal, indeed.
>
> Ikiwiki doesn't bother to simplify complex PageSpecs
> because it's difficult to do, and because all they use is some disk
> space. Consider what ikiwiki uses these dependencies for.
> All it wants to know is: does the PageSpec for this page it's considering
> rebuilding match any of the pages that have changed? Determining this is
> a simple operation -- the PageSpec is converted to perl code. The perl
> code is run.
>
> So the total impact of an ugly dependency like this is:
>
> 1. Some extra data read/written to disk.
> 2. Some extra space in memory.
> 3. A bit more data for the PageSpec translation code to handle. But that
> code is quite fast.
> 4. Typically one extra function call when the generated perl code is run.
> Ie, when the expression on the left-hand side fails, which typically
> happens after one (inexpensive) function call, it has to check
> the identical expression on the right hand side.
>
> So this is at best a wishlist todo item, not a bug. A PageSpec simplifier
> (or improved `pagespec_merge()` function) could be written and improve
> ikiwiki's memory and disk usage, but would it actually speed it up any?
> We'd have to see the code to the simplifier to know.
>
> --[[Joey]]