ccache: zero cache hit ratio on port update
rozhuk.im at gmail.com
Sun Dec 20 21:05:56 UTC 2020
I spent some time to digg into this.
This is my 2-3 attempt to fix it. 
Current we have normal cache hit ratio on port rebuild and
zero on version/hashtag/any_thing_that_change_port_src_dir_name.
Zero cache hit ratio even if only readme.md changed in project,
that causes hashtag->dir name change.
Most annoying effect of this - build time for heavy projects
is very different:
chorome: build ~4 hours, rebuild 15 minutes. (Ryzen 2700x)
I do not expext that 4h->15m, but even 2h - is good motivation for me.
I know two ways to fix it:
1. Change port system to use static names
(Can some one explain: why port system add version/hashtag/random to dir name?)
(Is it strongly required?)
2. Do something with ccache + out of source build:
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