Before the change garbage collector was not considering
`.drv` and outputs as alive even if configuration says otherwise.
As a result `nix store gc --dry-run` could visit (and parse)
`.drv` files multiple times (worst case it's quadratic).
It happens because `alive` set was populating only runtime closure
without regard for actual configuration. The change fixes it.
Benchmark: my system has about 139MB, 40K `.drv` files.
Performance before the change:
$ time nix store gc --dry-run
real 4m22,148s
Performance after the change:
$ time nix store gc --dry-run
real 0m14,178s
The current `--out-path` flag has two disadvantages when one is only
concerned with querying the names of outputs:
- it requires evaluating every output's `outPath`, which takes
significantly more resources and runs into more failures
- it destroys the information of the order of outputs so we can't tell
which one is the main output
This patch makes the output names always present (replacing paths with
`null` in JSON if `--out-path` isn't given), and adds an `outputName`
field.
When importing e.g. a local `nixpkgs` in a flake to test a change like
{
inputs.nixpkgs.url = path:/home/ma27/Projects/nixpkgs;
outputs = /* ... */
}
then the input is missing a `lastModified`-field that's e.g. used in
`nixpkgs.lib.nixosSystem`. Due to the missing `lastMoified`-field, the
mtime is set to 19700101:
result -> /nix/store/b7dg1lmmsill2rsgyv2w7b6cnmixkvc1-nixos-system-nixos-22.05.19700101.dirty
With this change, the `path`-fetcher now sets a `lastModified` attribute
to the `mtime` just like it's the case in the `tarball`-fetcher already.
When building NixOS systems with `nixpkgs` being a `path`-input and this
patch, the output-path now looks like this:
result -> /nix/store/ld2qf9c1s98dxmiwcaq5vn9k5ylzrm1s-nixos-system-nixos-22.05.20220217.dirty
Before the change on a system with `auto-optimise-store = true`:
$ nix store gc --verbose --max 1
deleted all the paths instead of one path (we requested 1 byte limit).
It happens because every file in `auto-optimise-store = true` has at
least 2 links: file itself and a link in /nix/store/.links/ directory.
The change conservatively assumes that any file that has one (as before)
or two links (assume auto-potimise mode) will free space.
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
help new users find a solution to their problem
./result/bin/nix-env -qa hello
warning: name collision in input Nix expressions, skipping '/home/artturin/.nix-defexpr/channels_root/master'
suggestion: remove 'master' from either the root channels or the user channels
hello-2.12
hello-2.12
This changes was taken from dynamic derivation (#4628). It` somewhat
undoes the refactors I first did for floating CA derivations, as the
benefit of hindsight + requirements of dynamic derivations made me
reconsider some things.
They aren't to consequential, but I figured they might be good to land
first, before the more profound changes @thufschmitt has in the works.
Continue progress on #5729.
Just as I hoped, this uncovered an issue: the daemon protocol is missing
a way to query build logs. This doesn't effect `unix://`, but does
effect `ssh://`. A FIXME is left for this, so we come back to it later.
no need for function<> with c++17 deduction. this saves allocations and virtual
calls, but has the same semantics otherwise. not going through function has the
side effect of giving compilers more insight into the cleanup code, so we need a
few local warning disables.
reduces peak hep memory use on eval of our test system from 264.4MB to 242.3MB,
possibly also a slight performance boost.
theoretically memory use could be cut down by another eight bytes per Pos on
average by turning it into a tuple containing an index into a global base
position table with row and column offsets, but that doesn't seem worth the
effort at this point.
This function is like buildPaths(), except that it returns a vector of
BuildResults containing the exact statuses and output paths of each
derivation / substitution. This is convenient for functions like
Installable::build(), because they then don't need to do another
series of calls to get the outputs of CA derivations. It's also a
precondition to impure derivations, where we *can't* query the output
of those derivations since they're not stored in the Nix database.
Note that PathSubstitutionGoal can now also return a BuildStatus.
```console
$ nix eval --expr '({ foo ? 1 }: foo) { fob = 2; }'
error: anonymous function at (string):1:2 called with unexpected argument 'fob'
at «string»:1:1:
1| ({ foo ? 1 }: foo) { fob = 2; }
| ^
Did you mean foo?
```
Not that because Nix will first check for _missing_ arguments before
checking for extra arguments, `({ foo }: foo) { fob = 1; }` will
complain about the missing `foo` argument (rather than extra `fob`) and
so won’t display a suggestion.
Make the evaluator show some suggestions when trying to access an
invalid field from an attrset.
```console
$ nix eval --expr '{ foo = 1; }.foa'
error: attribute 'foa' missing
at «string»:1:1:
1| { foo = 1; }.foa
| ^
Did you mean foo?
```
No real need for keeping a separate header for such a simple class.
This requires changing a bit `OrSuggestions<T>::operator*` to not throw
an `Error` to prevent a cyclic dependency. But since this error is only
thrown on programmer error, we can replace the whole method by a direct
call to `std::get` which will raise its own assertion if needs be.
Refactor the `size == 0` logic into a new helper function that
replaces dupStringWithLen.
The name had to change, because unlike a `dup`-function, it does
not always allocate a new string.
Sergei Trofimovich
Maximilian Bosch
Robert Hensing