[gentoo-portage-dev] [PATCH] portage: HTTP if-modified-since and compression

[Mark Kubacki]

Hi Portage devs,

The attached patches fix some issues I've noticed as maintainer and
user of Gentoo binhost(s). They're made against master/HEAD and can
easily be backported to 2.1*.

The first patch enables Portage to skip downloading a remote index if
the local copy is recent enough. E.g., the remote index didn't change
between to "emerge"-runs. This is done by setting "If-Modified-Since"
request-header. The server responds with HTTP code 304 and Portage
doesn't even load a single byte of the (large) index file.

By the second patch Portage will download remote indices—which are
text-files after all—compressed, if the remote server supports that.
Although de-compression introduces a small latency, this will save
bandwidth and transmission time. If the index needs to be fetched at
all, that is (see the patch above).

An index' TIMESTAMP entry is set before the corresponding file gets
written. If the difference between TIMESTAMP and modification time
("mtime") is greater than or the times span one second, remote index
files will be loaded despite the "If-Modified-Since" header. This is
because TIMESTAMP of the local copy is compared with the remote index'
"mtime". The third patch fixes that by setting "mtime" = TIMESTAMP.

-- 
Mark