need any info on substitutable paths, we just call the substituters
(such as download-using-manifests.pl) directly. This means that
it's no longer necessary for nix-pull to register substitutes or for
nix-channel to clear them, which makes those operations much faster
(NIX-95). Also, we don't have to worry about keeping nix-pull
manifests (in /nix/var/nix/manifests) and the database in sync with
each other.
The downside is that there is some overhead in calling an external
program to get the substitutes info. For instance, "nix-env -qas"
takes a bit longer.
Abolishing the substitutes table also makes the logic in
local-store.cc simpler, as we don't need to store info for invalid
paths. On the downside, you cannot do things like "nix-store -qR"
on a substitutable but invalid path (but nobody did that anyway).
* Never catch interrupts (the Interrupted exception).
`nix-store --delete'. But unprivileged users are not allowed to
ignore liveness.
* `nix-store --delete --ignore-liveness': ignore the runtime roots as
well.
process, so forward the operation.
* Spam the user about GC misconfigurations (NIX-71).
* findRoots: skip all roots that are unreadable - the warnings with
which we spam the user should be enough.
processes can register indirect roots. Of course, there is still
the problem that the garbage collector can only read the targets of
the indirect roots when it's running as root...
containing functions that operate on the Nix store. One
implementation is LocalStore, which operates on the Nix store
directly. The next step, to enable secure multi-user Nix, is to
create a different implementation RemoteStore that talks to a
privileged daemon process that uses LocalStore to perform the actual
operations.
Nix-env failed to call addPermRoot(), which is necessary to safely
add a new root. So if nix-env started after and finished before the
garbage collector, the user environment (plus all other new stuff)
it built might be garbage collected, leading to a dangling symlink
chain in ~/.nix-profile...
* Be more explicit if we block on the GC lock ("waiting for the big
garbage collector lock...").
* Don't loop trying to create a new generation. It's not necessary
anymore since profiles are locked nowadays.
deletes a path even if it is reachable from a root. However, it
won't delete a path that still has referrers (since that would
violate store invariants).
Don't try this at home. It's a useful hack for recovering from
certain situations in a somewhat clean way (e.g., holes in closures
due to disk corruption).
nix-store query options `--referer' and `--referer-closure' have
been changed to `--referrer' and `--referrer-closure' (but the old
ones are still accepted for compatibility).
to derivations in user environments. Nice for developers (since it
prevents build-time-only dependencies from being GC'ed, in
conjunction with `gc-keep-outputs'). Turned off by default.
for finding build-time dependencies (possibly after a build). E.g.,
$ nix-store -qb aterm $(nix-store -qd $(which strc))
/nix/store/jw7c7s65n1gwhxpn35j9rgcci6ilzxym-aterm-2.3.1
* Arguments to nix-store can be files within store objects, e.g.,
/nix/store/jw7c...-aterm-2.3.1/bin/baffle.
* Idem for garbage collector roots.
This was necessary becase root finding must be done after
acquisition of the global GC lock.
This makes `nix-collect-garbage' obsolete; it is now just a wrapper
around `nix-store --gc'.
* Automatically remove stale GC roots (i.e., indirect GC roots that
point to non-existent paths).
get rid of GC roots. Nix-build places a symlink `result' in the
current directory. Previously, removing that symlink would not
remove the store path being linked to as a GC root. Now, the GC
root created by nix-build is actually a symlink in
`/nix/var/nix/gcroots/auto' to `result'. So if that symlink is
removed the GC root automatically becomes invalid (since it can no
longer be resolved). The root itself is not automatically removed -
the garbage collector should delete dangling roots.
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.
being created after the garbage collector has read the temproots
directory. This blocks the creation of new processes, but the
garbage collector could periodically release the GC lock to allow
them to run.
that they are deleted in an order that maintains the closure
invariant.
* Presence of a path in a temporary roots file does not imply that all
paths in its closure are also present, so add the closure.
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.
