optimiseStore(): Use a content-addressed file store in /nix/store/.links

optimiseStore() now creates persistent, content-addressed hard links
in /nix/store/.links.  For instance, if it encounters a file P with
hash H, it will create a hard link

  P' = /nix/store/.link/<H>

to P if P' doesn't already exist; if P' exist, then P is replaced by a
hard link to P'.  This is better than the previous in-memory map,
because it had the tendency to unnecessarily replace hard links with a
hard link to whatever happened to be the first file with a given hash
it encountered.  It also allows on-the-fly, incremental optimisation.

0 files changed, 0 insertions, 0 deletions