On Sat, 24 Apr 2004, George Schlossnagle wrote:
> > What do you mean by that? APC doesn't require anything near a
> > realpath.
> > If you get rid of realpath() in PHP, APC will work just fine. With my
> > syscall hacks I am using APC this way and I just have 1 stat per file.
> > The only visible difference is when you ask APC which files it has
> > cached
> > and it doesn't return full-path filenames but rather just the paths
> > used
> > to include the files.
> >
> > For the top file there is no stat in PHP/APC at all anymore as we
> > inherit
> > the stat struct from Apache (which I guess is what you are alluding to)
> > and then for each include file only a single stat is needed. That is
> > nowhere near the equivalent of a realpath which adds N stats per file
> > where N is the depth of the file in the directory structure.
>
> Yes, that was what I was alluding to. That only works for the top
> level file though, not any includes. Without that though, you need to
> call apc_stat_paths(), which does this:
>
> paths = apc_tokenize(path, ':'); /* TODO - on windows, it's ';'
> */
> if (!paths)
> return -1;
>
> /* for each directory in paths, look for filename inside */
> for (i = 0; paths[i]; i++) {
> snprintf(filepath, sizeof(filepath), "%s/%s", paths[i],
> filename);
> if (stat(filepath, buf) == 0) {
> found = 1;
> break;
> }
> }
>
> And while not a realpath(), it does a similar sort of search (path here
> is the include_path for those following along at home). Fully
> qualifying your paths makes up for this, and the next best thing is to
> make sure your include_path is tight and optimally ordered.
Well, I disagree that this is anything like a realpath(). If your PEAR
directory is the first thing in the include_path (as in get rid of "."
from it) then this is a single stat call on any PEAR include regardless of
how deep your directory structure is. Compared to realpath where
including XML_RSS/RSS.php from a PEAR path of /usr/local/php/pear would be
6 stats.
We can't avoid a single stat per file, and on include_path includes we
can't avoid a single stat per attempted include_path component. The
single stats don't worry me very much and we could reduce this with an
intelligent request-spanning stat cache system.
-Rasmus
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