(e.g. an SSH connection problem) and permanent failures (i.e. the
builder failed). This matters to Hydra (it wants to know whether it
makes sense to retry a build).
allocate memory, which is verboten in signal handlers. This caused
random failures in the test suite on Mac OS X (triggered by the spurious
SIGPOLL signals on Mac OS X, which should also be fixed).
closure of the inputs. This really enforces that there can't be any
undeclared dependencies on paths in the store. This is done by
creating a fake Nix store and creating bind-mounts or hard-links in
the fake store for all paths in the closure. After the build, the
build output is moved from the fake store to the real store. TODO:
the chroot has to be on the same filesystem as the Nix store for
this to work, but this isn't enforced yet. (I.e. it only works
currently if /tmp is on the same FS as /nix/store.)
bind-mounts we do are only visible to the builder process and its
children. So accidentally doing "rm -rf" on the chroot directory
won't wipe out /nix/store and other bind-mounted directories
anymore. Also, the bind-mounts in the private namespace disappear
automatically when the builder exits.
necessary that at least one build hook doesn't return "postpone",
otherwise nix-store will barf ("waiting for a build slot, yet there
are no running children"). So inform the build hook when this is
the case, so that it can start a build even when that would exceed
the maximum load on a machine.
nix-store -r (or some other operation) is started via ssh, it will
at least have a chance of terminating quickly when the connection is
killed. Right now it just runs to completion, because it never
notices that stderr is no longer connected to anything. Of course
it would be better if sshd would just send a SIGHUP, but it doesn't
(https://bugzilla.mindrot.org/show_bug.cgi?id=396).
derivation should be a source rather than a derivation dependency of
the call to the NAR derivation. Otherwise the derivation (and all
its dependencies) will be built as a side-effect, which may not even
succeed.
SHA-256 outputs of fixed-output derivations. I.e. they now produce
the same store path:
$ nix-store --add x
/nix/store/j2fq9qxvvxgqymvpszhs773ncci45xsj-x
$ nix-store --add-fixed --recursive sha256 x
/nix/store/j2fq9qxvvxgqymvpszhs773ncci45xsj-x
the latter being the same as the path that a derivation
derivation {
name = "x";
outputHashAlgo = "sha256";
outputHashMode = "recursive";
outputHash = "...";
...
};
produces.
This does change the output path for such fixed-output derivations.
Fortunately they are quite rare. The most common use is fetchsvn
calls with SHA-256 hashes. (There are a handful of those is
Nixpkgs, mostly unstable development packages.)
* Documented the computation of store paths (in store-api.cc).
dependency. `storePath /nix/store/bla' gives exactly the same
result as `toPath /nix/store/bla', except that the former includes
/nix/store/bla in the dependency context of the string.
Useful in some generated Nix expressions like nix-push, which now
finally does the right thing wrt distributed builds. (Previously
the path to be packed wasn't an explicit dependency, so it wouldn't
be copied to the remote machine.)
subtle and often hard-to-reproduce bugs where programs in pipes
either barf with a "Broken pipe" message or not, depending on the
exact timing conditions. This particularly happened in GNU M4 (and
Bison, which uses M4).
disasters involving `rm -rf' on bind mounts. Will try the
definitive fix (per-process mounts, apparently possible via the
CLONE_NEWNS flag in clone()) some other time.
accessed time of paths that may be deleted. Anything more recently
used won't be deleted. The time is specified in time_t,
e.g. seconds since 1970-01-01 00:00:00 UTC; use `date +%s' to
convert to time_t from the command line.
Example: to delete everything that hasn't been used in the last two
months:
$ nix-store --gc -v --max-atime $(date +%s -d "2 months ago")
order of ascending last access time. This is useful in conjunction
with --max-freed or --max-links to prefer deleting non-recently used
garbage, which is good (especially in the build farm) since garbage
may become live again.
The code could easily be modified to accept other criteria for
ordering garbage by changing the comparison operator used by the
priority queue in collectGarbage().
