Without the change any CA deletion triggers linear scan on large
RealisationsRefs table:
sqlite>.eqp full
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SCAN RealisationsRefs
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
With the change it gets turned into a lookup:
sqlite> CREATE INDEX IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SEARCH RealisationsRefs USING INDEX IndexRealisationsRefsRealisationReference (realisationReference=?)
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
If the derivation `foo` depends on `bar`, and they both have the same
output path (because they are CA derivations), then this output path
will depend both on the realisation of `foo` and of `bar`, which
themselves depend on each other.
This confuses SQLite which isn’t able to automatically solve this
diamond dependency scheme.
Help it by adding a trigger to delete all the references between the
relevant realisations.
Fix#5320
Otherwise the clang builds fail because the constructor of `SQLiteBusy`
inherits it, `SQLiteError::_throw` tries to call it, which fails.
Strangely, gcc works fine with it. Not sure what the correct behavior is
and who is buggy here, but either way, making it public is at the worst
a reasonable workaround
Don’t say that the derivation is CA as it might happen on a non-ca
derivation too.
Technically we could always recover _something_ for a purely
input-addressed derivation (like we already do when the `ca-derivations`
xp feature isn’t enabled), but it seems better to consistently fail −
the end-result wouldn’t really make sense anyways in most cases.
This ensures that use-sites properly trigger new monomorphisations on
one hand, and on the other hand keeps the main `sqlite.hh` clean and
interface-only. I think that is good practice in general, but in this
situation in particular we do indeed have `sqlite.hh` users that don't
need the `throw_` function.
nix show-config --json was serializing experimental features as ints.
nlohmann::json will automatically use these definitions to serialize
and deserialize ExperimentalFeatures.
Strictly, we don't use the from_json instance yet, it's provided for
completeness and hopefully future use.
Requested by ppepino on the Matrix:
https://matrix.to/#/!KqkRjyTEzAGRiZFBYT:nixos.org/$Tb32BS3rVE2BSULAX4sPm0h6CDewX2hClOTGzTC7gwM?via=nixos.org&via=matrix.org&via=nixos.dev
This adds a new command, :bl, which works like :b but also creates
a GC root symlink to the various derivation outputs.
ckie@cookiemonster ~/git/nix -> ./outputs/out/bin/nix repl
Welcome to Nix 2.6.0. Type :? for help.
nix-repl> :l <nixpkgs>
Added 16118 variables.
nix-repl> :b runCommand "hello" {} "echo hi > $out"
This derivation produced the following outputs:
./repl-result-out -> /nix/store/kidqq2acdpi05c4a9mlbg2baikmzik44-hello
[1 built, 0.0 MiB DL]
ckie@cookiemonster ~/git/nix -> cat ./repl-result-out
hi
In particular, this means that 'nix eval` (which uses toValue()) no
longer auto-calls functions or functors (because
AttrCursor::findAlongAttrPath() doesn't).
Fixes#6152.
Also use ref<> in a few places, and don't return attrpaths from
getCursor() because cursors already have a getAttrPath() method.
Previously it only logged the builder's path, this changes it to log the
arguments at the same log level, and the environment variables at the
vomit level.
This helped me debug https://github.com/svanderburg/node2nix/issues/75
This was a problem when writing a fetcher that uses e.g. sha256 hashes
for revisions. This doesn't actually do anything new, but allows for
creating such fetchers in the future (perhaps when support for Git's
SHA256 object format gains more popularity).
The filter expects all paths to have a prefix of the raw `actualUrl`, but
`Store::addToStore(...)` provides absolute canonicalized paths.
To fix this create an absolute and canonicalized path from the `actualUrl` and
use it instead.
Fixes#6195.
This was caused by SubstitutionGoal not setting the errorMsg field in
its BuildResult. We now get a more descriptive message than in 2.7.0, e.g.
error: path '/nix/store/13mh...' is required, but there is no substituter that can build it
instead of the misleading (since there was no build)
error: build of '/nix/store/13mh...' failed
Fixes#6295.
Saving the cwd fd didn't actually work well -- prior to this commit, the
following would happen:
: ~/w/vc/nix ; doas outputs/out/bin/nix --experimental-features 'nix-command flakes' run nixpkgs#coreutils -- --coreutils-prog=pwd
pwd: couldn't find directory entry in ‘../../../..’ with matching i-node
: ~/w/vc/nix ; doas outputs/out/bin/nix --experimental-features 'nix-command flakes' develop -c pwd
pwd: couldn't find directory entry in ‘../../../..’ with matching i-node
This doesn't work very well (maybe I'm misunderstanding the desired
implementation):
: ~/w/vc/nix ; doas outputs/out/bin/nix --experimental-features 'nix-command flakes' develop -c pwd
pwd: couldn't find directory entry in ‘../../../..’ with matching i-node
I regularly pass around simple scripts by using nix-shell as the script
interpreter, eg. like this:
#!/usr/bin/env nix-shell
#!nix-shell -p dd_rescue coreutils bash -i bash
While this works most of the time, I recently had one occasion where it
would not and the above would result in the following:
$ sudo ./myscript.sh
bash: ./myscript.sh: No such file or directory
Note the "sudo" here, because this error only occurs if we're root.
The reason for the latter is because running Nix as root means that we
can directly access the store, which makes sure we use a filesystem
namespace to make the store writable. XXX - REWORD!
So when stracing the process, I stumbled on the following sequence:
openat(AT_FDCWD, "/proc/self/ns/mnt", O_RDONLY) = 3
unshare(CLONE_NEWNS) = 0
... later ...
getcwd("/the/real/cwd", 4096) = 14
setns(3, CLONE_NEWNS) = 0
getcwd("/", 4096) = 2
In the whole strace output there are no calls to chdir() whatsoever, so
I decided to look into the kernel source to see what else could change
directories and found this[1]:
/* Update the pwd and root */
set_fs_pwd(fs, &root);
set_fs_root(fs, &root);
The set_fs_pwd() call is roughly equivalent to a chdir() syscall and
this is called when the setns() syscall is invoked[2].
[1]: b14ffae378/fs/namespace.c (L4659)
[2]: b14ffae378/kernel/nsproxy.c (L346)
Impure derivations are derivations that can produce a different result
every time they're built. Example:
stdenv.mkDerivation {
name = "impure";
__impure = true; # marks this derivation as impure
outputHashAlgo = "sha256";
outputHashMode = "recursive";
buildCommand = "date > $out";
};
Some important characteristics:
* This requires the 'impure-derivations' experimental feature.
* Impure derivations are not "cached". Thus, running "nix-build" on
the example above multiple times will cause a rebuild every time.
* They are implemented similar to CA derivations, i.e. the output is
moved to a content-addressed path in the store. The difference is
that we don't register a realisation in the Nix database.
* Pure derivations are not allowed to depend on impure derivations. In
the future fixed-output derivations will be allowed to depend on
impure derivations, thus forming an "impurity barrier" in the
dependency graph.
* When sandboxing is enabled, impure derivations can access the
network in the same way as fixed-output derivations. In relaxed
sandboxing mode, they can access the local filesystem.
The return value of BaseError::addTrace(...) is never used and
error-prone as subclasses calling it will return a BaseError instead of
the subclass.
This commit changes its return value to be void.
Rather than having four different but very similar types of hashes, make
only one, with a tag indicating whether it corresponds to a regular of
deferred derivation.
This implies a slight logical change: The original Nix+multiple-outputs
model assumed only one hash-modulo per derivation. Adding
multiple-outputs CA derivations changed this as these have one
hash-modulo per output. This change is now treating each derivation as
having one hash modulo per output.
This obviously means that we internally loose the guaranty that
all the outputs of input-addressed derivations have the same hash
modulo. But it turns out that it doesn’t matter because there’s nothing
in the code taking advantage of that fact (and it probably shouldn’t
anyways).
The upside is that it is now much easier to work with these hashes, and
we can get rid of a lot of useless `std::visit{ overloaded`.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
Before this change, processLine always uses the first character
as the start of the line. This cause whitespaces to matter at the
beginning of the line whereas it does not matter anywhere else.
This commit trims leading white spaces of the string line so that
subsequent operations can be performed on the string without explicitly
tracking starting and ending indices of the string.
This avoids an infinite loop in the final test in
tests/binary-cache.sh. I think this was only not triggered previously
by accident (because we were clearing wantedOutputs in between).
Yorick
mei (ckie)
Maximilian Bosch