[trondheim-pts] Downloading Caching Support

[Michael Larabel]

Following the 0.5.1 release this morning, download caching support for 
the Phoronix Test Suite has been pushed into the git tree 
(http://www.phorogit.com/index.php?p=phoronix-test-suite.git). This 
caching support is ideal for users with multiple systems or for users 
just wishing to backup their downloaded files in order to save bandwidth 
in the future.

By running "*phoronix-test-suite make-download-cache*", it will copy all 
files downloaded locally by the Phoronix Test Suite and places them 
inside *~/.phoronix-test-suite/download-cache* by default. However, you 
can override this location using the *DOWNLOAD_CACHE* environmental 
variable. By running *DOWNLOAD_CACHE=~/downloads/ phoronix-test-suite 
make-download-cache* it will save the files to ~/downloads/ and likewise 
if running *DOWNLOAD_CACHE=~/downloads/ phoronix-test-suite install 
universe*, it will use this custom directory for obtaining files 
previously downloaded. It's hooked in where if the file can be found in 
the cache and its MD5 sum is verified, it will just copy that file 
instead of downloading it from the Internet. Running make-download-cache 
on an existing cache will just update the files where the MD5s have 
changed or where the files were previously not downloaded.

This feature relies upon the recent downloads.xml introduction for the 
test profiles, in order to manage the download URLs and MD5 check-sums. 
In addition, through the downloads.xml file it can determine what files 
have been downloaded (instead of files in turn being extracted from a 
downloaded file or created by one of the test scripts).

Previously you could have (and still could) just copied the 
~/.phoronix-test-suite/installed-tests/ directory to another PC or 
backup medium, but I don't view that as a viable. In the copying process 
some files could be corrupted, file permissions changed, and it would 
just take immensely longer to do since *everything* is then being 
copied. Here if you just make the download cache and then copy the 
resulting directory to another test system, it's just the downloaded and 
compressed files, so it takes up less room, is a much cleaner process, 
and eliminates many headaches.

Michael