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.

1 files changed, 2 insertions, 8 deletions

diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 23863525fe8a..82e08fecf22a 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -746,18 +746,12 @@ static void showOptimiseStats(OptimiseStats & stats)
    files with the same contents. */
 static void opOptimise(Strings opFlags, Strings opArgs)
 {
-    if (!opArgs.empty())
+    if (!opArgs.empty() || !opFlags.empty())
         throw UsageError("no arguments expected");
 
-    bool dryRun = false;
-
-    foreach (Strings::iterator, i, opFlags)
-        if (*i == "--dry-run") dryRun = true;
-        else throw UsageError(format("unknown flag `%1%'") % *i);
-
     OptimiseStats stats;
     try {
-        ensureLocalStore().optimiseStore(dryRun, stats);
+        ensureLocalStore().optimiseStore(stats);
     } catch (...) {
         showOptimiseStats(stats);
         throw;