the existing logic for obtaining a list of firmware packages always
downloaded a fresh copy of the archive content file, deleting the file
already in the cache. here we move to actually making use of the cache.
this helps when building multiple times, at least for the same distro. the
package list obtained is rarely going to change after all. it could of
course differ between distros, but the cache is per-distro, as it has
always been.
we of course here switch to caching each of the archive-area files
individually rather than having one file that gets overwritten (or
appended to in the case of when we kept the decompressed file).
Gbp-Dch: Short
Closes: #952911
the existing logic was to decompress the contents file from the downloaded
archive to disk, then process it to obtain a package list. the largest
one by far is for 'main'; 'non-free' and 'contrib' are tiny in comparison.
for sid-amd64 currently, the archive file is 37 MB, while the decompressed
file it contains is 592.3 MB.
we always delete the files and download afresh (currently), and a previous
commit optimised by deleting the files once we're done with them to avoid
wasting disk space leaving them behind.
here we switch to storing the downloaded compressed file to disk instead,
reducing disk space usage (and IO) by hundreds of megabytes; piping the
decompression directly into awk instead of having awk read from the stored
file.
this moves the appending of new items into the list back within the archive
area loop, which is fine since we're replacing the file for each loop now
so the previous issue relating to appending is of no concern.
Gbp-Dch: Short
Closes: #952910
Edit: There were four copies of the same logic to keep in sync;
Originally this patch deduplicated each file, but leaving a copy of
the new function in each, thus reducing the duplication but not
eliminating it. A later patch moved it into a shared function file
following further enhancements to the code in question. This has
since been revised to have the function moved to a shared file here,
which simplifies and gives a cleaner diff.
Gbp-Dch: Short
Closes: #952908
Lyndon Brown