[Yum-devel] parallel metadata downloading

[Zdeněk Pavlas]

Hello,

So, this is the second attempt, keeping the original
_commonRetrieveDataMD behavior.  It's just re-implemented
in retrievAllMD() to run in parallel.

[PATCH 1/4] _retrieveMD(): make it useable for async downloading.
[PATCH 2/4] _commonRetrieveDataMD(): split the code

.. these are just a rewrite of original code.

[PATCH 3/4] retrievAllMD(): parallel metadata downloading

This we call just before postreposetup.  That's mainly 
because of the langpacks plugin, that touches repoXML
in all enabled repositories, so it'd trigger synchronous
downloads.

[PATCH 4/4] populateSack(): parallel metadata downloading

Copied from the previous patchset.  This parallelizes
also the other code path, used when downloading filelists.