Commit graph

8 commits

Author SHA1 Message Date
Eelco Dolstra dcc37c236c * nix-store, nix-instantiate: added an option `--add-root' to
immediately add the result as a permanent GC root.  This is the only
  way to prevent a race with the garbage collector.  For instance, the
  old style

    ln -s $(nix-store -r $(nix-instantiate foo.nix)) \
      /nix/var/nix/gcroots/result

  has two time windows in which the garbage collector can interfere
  (by GC'ing the derivation and the output, respectively).  On the
  other hand,

    nix-store --add-root /nix/var/nix/gcroots/result -r \
      $(nix-instantiate --add-root /nix/var/nix/gcroots/drv \
        foo.nix)

  is safe.

* nix-build: use `--add-root' to prevent GC races.
2005-02-01 12:36:25 +00:00
Eelco Dolstra 207bdcbe86 * Automatically remove temporary root files. 2005-01-31 21:20:59 +00:00
Eelco Dolstra 33c5d23b81 * Don't delete active lock files. 2005-01-31 12:19:53 +00:00
Eelco Dolstra 1328aa3307 * Start of concurrent garbage collection. Processes write temporary
roots to a per-process temporary file in /nix/var/nix/temproots
  while holding a write lock on that file.  The garbage collector
  acquires read locks on all those files, thus blocking further
  progress in other Nix processes, and reads the sets of temporary
  roots.
2005-01-31 10:27:25 +00:00
Eelco Dolstra c505702265 * Fix and simplify the garbage collector (it's still not concurrent,
though).  In particular it's now much easier to register a GC root.
  Just place a symlink to whatever store path it is that you want to
  keep in /nix/var/nix/gcroots.
2005-01-27 15:21:29 +00:00
Eelco Dolstra 96de272b48 * Renamed normalise.cc' -> build.cc', `storeexprs.cc' ->
`derivations.cc', etc.
* Store the SHA-256 content hash of store paths in the database after
  they have been built/added.  This is so that we can check whether
  the store has been messed with (a la `rpm --verify').
* When registering path validity, verify that the closure property
  holds.
2005-01-19 16:39:47 +00:00
Eelco Dolstra eb233e728f * `--min-age' flag in nix-store and nix-collect-garbage to only delete
unreachable paths that haven't been used for N hours.  For instance,
  `nix-collect-garbage --min-age 168' only deletes paths that haven't
  been accessed in the last week.

  This is useful for instance in the build farm where many derivations
  can be shared between consecutive builds, and we wouldn't want a
  garbage collect to throw them all away.  We could of course register
  them as roots, but then we'd to unregister them at some point, which
  would be a pain to manage.  The `--min-age' flag gives us a sort of
  MRU caching scheme.

  BUG: this really shouldn't be in gc.cc since that violates
  mechanism/policy separation.
2004-08-25 16:54:08 +00:00
Eelco Dolstra 818047881e * Put the garbage collector in nix-store: operation `--gc',
suboperations `--print-live', `--print-dead', and `--delete'.  The
  roots are not determined by nix-store; they are read from standard
  input.  This is to make it easy to customise what the roots are.

  The collector now no longer fails when store expressions are missing
  (which legally happens when using substitutes).  It never tries to
  fetch paths through substitutes.

  TODO: acquire a global lock on the store while garbage collecting.
  
* Removed `nix-store --delete'.
2004-08-25 11:43:49 +00:00