occurances of a component. If the shortest path distance between a
component P and Q in the referers graph is D, then the contribution
of Q to the use of P is 1 / R^D, where R >= 1, typically 2. This
expresses that distant indirect uses are less important than nearby
uses.
For instance, this can disambiguate between the bootstrap GCC in
Nixpkgs and the GCC of the final stdenv (the former has more uses,
but they are further away), and between the GCC of the final stdenv
and the GCC+G77 build (the latter has very few uses).
by the build farm. See e.g.,
http://catamaran.labs.cs.uu.nl/dist/nixpkgs-0.8/nixpkgs-0.7pre2302/;
the user can click on packages, and they will be installed (assuming
the `application/nix-package' MIME type has been associated with
`nix-install-package').
Nix expressions are no longer involved: a "package" is just a
pointer to a manifest, and the top-level store derivation to be
added to the user environment. This makes these packages
independent from Nix expression evolution.
Note that we install the store derivation ($drvPath), not the
resulting output path ($outPath). This is equivalent, except that
installing the derivation maintains the back-link from the output
path to the derivation that built it. This is useful for
maintenance.
* Automatically re-exec in an xterm so that the user sees something
when `nix-install-package' is run from a browser.
too.
* Change the default hash for nix-prefetch-url back to md5, since
that's what we use in Nixpkgs (for now; a birthday attack is rather
unlikely there).
continue building when one fails unless `--keep-going' is
specified.
* When `--keep-going' is specified, print out the set of failing
derivations at the end (otherwise it can be hard to find out which
failed).
multiple times is also a top-level goal, then the second and later
instantiations would never be created because there would be a
stable pointer to the first one that would keep it alive in the
WeakGoalMap.
* Some tracing code for debugging this kind of problem.
of the given derivation. Useful for getting a quick overview of how
something was built. E.g., to find out how the `baffle' program in
your user environment was built, you can do
$ nix-store -q --tree $(nix-store -qd $(which baffle))
Tree nesting depth is minimised (?) by topologically sorting paths
under the relation A < B iff A \in closure(B).
environment elements from one user environment to another, e.g.,
$ nix-env -i --from-profile /nix/var/nix/profiles/other-profile aterm
copies the `aterm' component installed in the `other-profile' to the
user's current profile.
user environment, e.g.,
$ nix-env -i /nix/store/z58v41v21xd3ywrqk1vmvdwlagjx7f10-aterm-2.3.1.drv
or
$ nix-env -i /nix/store/hsyj5pbn0d9iz7q0aj0fga7cpaadvp1l-aterm-2.3.1
This is useful because it allows Nix expressions to be bypassed
entirely. For instance, if only a nix-pull manifest is provided,
plus the top-level path of some component, it can be installed
without having to supply the Nix expression (e.g., for obfuscation,
or to be independent of Nix expression language changes or context
dependencies).
install derivations from a Nix expression specified on the command
line. This is particularly useful for disambiguation if there are
multiple derivations with the same name. For instance, in Nixpkgs,
to install the Firefox wrapper rather than the plain Firefox
component:
$ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper'
The Nix expressions should be functions to which the default Nix
expression (in this case, `i686-linux.nix') is passed, hence `x:
...'.
This might also be a nice way to deal with high-level (user-level)
variability, e.g.,
$ nix-env -f ./server.nix -i -E 'x: x {port = 8080; ssl = false;}'
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.
* Set the references for the user environment manifest properly.
* Don't copy the manifest (this was accidental).
* Don't store derivation paths in the manifest (maybe this should be
made optional). This cleans up the semantics of nix-env, which were
weird.
* Hash on the output paths of activated components, not on derivation
paths. This is because we don't know the derivation path of already
installed components anymore, and it allows the installation of
components by store path (skipping Nix expressions entirely).
* Query options `--out-path' and `--drv-path' to show the output and
derivation paths of components, respectively (the latter replaces
the `--expr' query).
* Removed some dead code (successor stuff) from nix-push.
* Updated terminology in the tests (store expr -> drv path).
* Check that the deriver is set properly in the tests.
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.
