Re: Calc: Further cache simulation results

> On October 1, 2018 at 5:31 AM Michael Meeks <michael.meeks@collabora.com> wrote:

>       Kohei poked at a chunk of profiles like this in the past; probably
> worth getting his input; any thoughts ?

So, I believe when I reworked the internals of SvlListener & SvlBroadcaster to switch to 
unorderd_set back in 2013, I did consider using vector instead, but decided to stick with 
unordered_set.  I don't remember the exact reasoning behind it, but I don't think it was based on 
any real-world profile results showing advantages of unordered_set over vector.  I'm all speaking 
from memory here, so apply appropriate amount of skepticism ;-), but I don't think the difference 
between use of vector and unordered_set was that significant with the few cases that I have tried.

I felt it was safe to use unordered_set for this simply because, while use of vector may improve 
performance in certain situations, it may worsen performance in others.  I just felt it was a bit 
of a gamble to use vector, and I wanted to play safe.

Also, like Michael said, ultimately I feel that we should be using a drastically different data 
structure to manage formula cell & formula group dependency to potentially win substantially and/or 
reduce the cost of maintenance.  I'm currently looking into using R tree for this, which is now 
available in mdds.  So far I haven't gone far enough to run any profiles yet.

Kohei

--
Kohei Yoshida, LibreOffice Calc volunteer hacker