Re: readdir vs. getdirentriesattr
Re: readdir vs. getdirentriesattr
- Subject: Re: readdir vs. getdirentriesattr
- From: Thomas Tempelmann <email@hidden>
- Date: Mon, 29 Apr 2019 23:22:22 +0200
> The volume ID is at a higher layer, but the enumeration code attempts to
> retrieve the value less than once per URL returned. That said, if the
> directory hierarchy has few items per directory, the number of times it is
> retrieved will be higher. You can write a bug report and I'll look to see
> if there are ways to improve the performance.
>
As I just wrote, going with your proposed enumeratorAtURL: method takes
care of that already. I may still write a report, and will let you know if
I do.
Though I still haven't gotten to see if I can speed up recursive search by
using multiple threads for each directory read. If that helps, then I
cannot use enumeratorAtURL for that but would have to revert to classic
recursion, and which point the volumeID checking comes into play again
(but, with only checking it whenever I enter a dir, it'll be less of an
impact).
> In the meantime, there's something you could do to improve the performance
> (even if our code changes). You can get the volumeIdentifier for the
> directory you start enumerating from. It will be the same for the entire
> enumeration except when directories are seen on other file systems (today,
> that's volume mount points and mount triggers). Like this:
>
I already do that in my actual working code. I was just showing this more
inefficient way of ALWAYS getting the value in order to demonstrate its
performance impact.
It used to be based on heavily modified fts(3). I rewrote it for Mojave to
> improve the memory footprint. It uses getattrlistbulk()for everything
> except when ti sees a mount point, and then it calls getattrlist on the
> mount point path to get the attributes from the other file system's root
> directory.
>
Glad to see you're still on top of it.
Thomas
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