bug#26201: No notification of cache misses when downloading substitutes

[<dian_cecht@zoho.com>]

On Tue, 21 Mar 2017 03:46:29 +0100
Tobias Geerinckx-Rice <me@tobias.gr> wrote:

> Hullo,
> 
> On 21/03/17 02:44, dian_cecht@zoho.com wrote:
> > Just ran guix pull and guix package -u, and found some of the
> > programs download VERY slowly (<100kb/s, usually around 95). I
> > asked on #guix and lfam mentioned it was probably a cache miss.  
> 
> Do you mean that *substitutes* existed, but were not yet on
> mirror.hydra.gnu.org and so were silently proxied from the much slower
> hydra.gnu.org?

The URL displayed during the download was mirror.hydra.gnu.org. 

> 
> Or did Guix fall back to downloading *source* tarballs from some slow
> upstream to build locally?

It was a binary download, not source. At least, I don't recall anything
about compiles at any point (and I'm sure it didn't take long enough to
do that; one package was icecat which I'm sure wouldn't have downloaded
at 90k/s then compiled in less than 15 minutes (fwiw, according to my
build logs firefox takes about 2 hours to build, so unless icecat is
magically orders of magnitude faster to build, then I'm sure it was
just a download + install, and not download + compile + install)