we'll retain the old coerceToString interface that returns a string, but callers
that don't need the returned value to outlive the Value it came from can save
copies by using the new interface instead. for values that weren't stringy we'll
pass a new buffer argument that'll be used for storage and shouldn't be
inspected.
It’s totally valid to have entries in `NIX_PATH` that aren’t valid paths
(they can even be arbitrary urls or `channel:<channel-name>`).
Fix#5998 and #5980
keeping it as a simple data member means it won't be scanned by the GC, so
eventually the GC will collect a cache that is still referenced (resulting in
use-after-free of cache elements).
fixes#5962
- Make passing the position to `forceValue` mandatory,
this way we remember people that the position is
important for better error messages
- Add pos to all `forceValue` calls
If we want to be careful about hitting the stack protector page, we should use `-fstack-check` instead.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
This no longer worked correctly because 'path' is uninitialised when
an exception occurs, leading to errors like
… while importing ''
at /nix/store/rrzz5b1pshvzh1437ac9nkl06br81lkv-source/flake.nix:352:13:
So move the adding of the error context into realisePath().
This was removed in 2e199673a5 when
`copyPath` transitioned to use `RealisedPath`. But then in
e9848beca7 we added it back just for
`realisedPath`.
I think it is a good utility function --- one can easily imagine it
becoming optimized in the future, and copying paths *violating* the
closure is a very niche feature.
So if we have `copyPaths` for both sorts of paths, I think we should
have `copyClosure` for both sorts too.
if we defer the duplicate argument check for lambda formals we can use more
efficient data structures for the formals set, and we can get rid of the
duplication of formals names to boot. instead of a list of formals we've seen
and a set of names we'll keep a vector instead and run a sort+dupcheck step
before moving the parsed formals into a newly created lambda. this improves
performance on search and rebuild by ~1%, pure parsing gains more (about 4%).
this does reorder lambda arguments in the xml output, but the output is still
stable. this shouldn't be a problem since argument order is not semantically
important anyway.
before
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.550 s ± 0.060 s [User: 6.470 s, System: 1.664 s]
Range (min … max): 8.435 s … 8.666 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 346.7 ms ± 2.1 ms [User: 312.4 ms, System: 34.2 ms]
Range (min … max): 343.8 ms … 353.4 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.720 s ± 0.031 s [User: 2.415 s, System: 0.231 s]
Range (min … max): 2.662 s … 2.780 s 20 runs
after
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.462 s ± 0.063 s [User: 6.398 s, System: 1.661 s]
Range (min … max): 8.339 s … 8.542 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 329.1 ms ± 1.4 ms [User: 296.8 ms, System: 32.3 ms]
Range (min … max): 326.1 ms … 330.8 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.687 s ± 0.035 s [User: 2.392 s, System: 0.228 s]
Range (min … max): 2.626 s … 2.754 s 20 runs
This removes a dynamic stack allocation, making the derivation
unparsing logic robust against overflows when large strings are
added to a derivation.
Overflow behavior depends on the platform and stack configuration.
For instance, x86_64-linux/glibc behaves as (somewhat) expected:
$ (ulimit -s 20000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix)
error: stack overflow (possible infinite recursion)
$ (ulimit -s 40000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix)
error: expression does not evaluate to a derivation (or a set or list of those)
However, on aarch64-darwin:
$ nix-instantiate big-attr.nix ~
zsh: segmentation fault nix-instantiate big-attr.nix
This indicates a slight flaw in the single stack protection page
approach that is not encountered with normal stack frames.
string expressions by and large do not need the benefits a Symbol gives us,
instead they pollute the symbol table and cause unnecessary overhead for almost
all strings. the one place we can think of that benefits from them (attrpaths
with expressions) extracts the benefit in the parser, which we'll have to touch
anyway when changing ExprString to hold strings.
this gives a sizeable improvement on of 3-5% on all benchmarks we've run.
before
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.844 s ± 0.045 s [User: 6.750 s, System: 1.663 s]
Range (min … max): 8.758 s … 8.922 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 367.4 ms ± 3.3 ms [User: 332.3 ms, System: 35.2 ms]
Range (min … max): 364.0 ms … 375.2 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.810 s ± 0.030 s [User: 2.517 s, System: 0.225 s]
Range (min … max): 2.742 s … 2.854 s 20 runs
after
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.533 s ± 0.068 s [User: 6.485 s, System: 1.642 s]
Range (min … max): 8.404 s … 8.657 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 347.6 ms ± 3.1 ms [User: 313.1 ms, System: 34.5 ms]
Range (min … max): 343.3 ms … 354.6 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.709 s ± 0.032 s [User: 2.414 s, System: 0.232 s]
Range (min … max): 2.655 s … 2.788 s 20 runs
Unless `--precise` is passed, make `nix why-depends` only show the
dependencies between the store paths, without introspecting them to
find the actual references.
This also makes it ~3x faster
it can be replaced with StringToken if we add another bit if information to
StringToken, namely whether this string should take part in indentation scanning
or not. since all escaping terminates indentation scanning we need to set this
bit only for the non-escaped IND_STRING rule.
this improves performance by about 1%.
before
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.880 s ± 0.048 s [User: 6.809 s, System: 1.643 s]
Range (min … max): 8.781 s … 8.993 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 375.0 ms ± 2.2 ms [User: 339.8 ms, System: 35.2 ms]
Range (min … max): 371.5 ms … 379.3 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.831 s ± 0.040 s [User: 2.536 s, System: 0.225 s]
Range (min … max): 2.769 s … 2.912 s 20 runs
after
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 8.832 s ± 0.048 s [User: 6.757 s, System: 1.657 s]
Range (min … max): 8.743 s … 8.921 s 20 runs
nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 367.4 ms ± 3.2 ms [User: 332.7 ms, System: 34.7 ms]
Range (min … max): 364.6 ms … 374.6 ms 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.810 s ± 0.030 s [User: 2.517 s, System: 0.225 s]
Range (min … max): 2.742 s … 2.854 s 20 runs
This is needed to get the path of a derivation that might not exist
(e.g. for 'nix store copy-log').
InstallableStorePath::toDerivedPaths() cannot be used for this because
it calls readDerivation(), so it fails if the store doesn't have the
derivation.
When stderr is not connected to a tty, show "building" and
"substituting" messages, a-la nix-build et al.
Closes https://github.com/NixOS/nix/issues/4402
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
gives about 1% improvement on system eval, a bit less on nix search.
# before
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 7.419 s ± 0.045 s [User: 6.362 s, System: 0.794 s]
Range (min … max): 7.335 s … 7.517 s 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.921 s ± 0.023 s [User: 2.626 s, System: 0.210 s]
Range (min … max): 2.883 s … 2.957 s 20 runs
# after
nix search --no-eval-cache --offline ../nixpkgs hello
Time (mean ± σ): 7.370 s ± 0.059 s [User: 6.333 s, System: 0.791 s]
Range (min … max): 7.286 s … 7.541 s 20 runs
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.891 s ± 0.033 s [User: 2.606 s, System: 0.210 s]
Range (min … max): 2.823 s … 2.958 s 20 runs
`nix why-depends` is piping its output into a pager by default.
However the pager was only started after the first path is printed,
causing it to be excluded from the pager output.
(Actually the pager was started *inside* the recursive function that was
printing the dependency chain, so a new instance was started at each
level. It’s a little miracle that it worked at all).
Fix#5911
mainly to avoid an allocation and a copy of a string that can be
modified in place (ever since EvalState holds on to the buffer, not the
generated parser itself).
# before
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 571.7 ms ± 2.4 ms [User: 563.3 ms, System: 8.0 ms]
Range (min … max): 566.7 ms … 579.7 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 376.6 ms ± 1.0 ms [User: 345.8 ms, System: 30.5 ms]
Range (min … max): 374.5 ms … 379.1 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.922 s ± 0.006 s [User: 2.707 s, System: 0.215 s]
Range (min … max): 2.906 s … 2.934 s 50 runs
# after
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 570.4 ms ± 2.8 ms [User: 561.3 ms, System: 8.6 ms]
Range (min … max): 564.6 ms … 578.1 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 375.4 ms ± 1.3 ms [User: 343.2 ms, System: 31.7 ms]
Range (min … max): 373.4 ms … 378.2 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.925 s ± 0.006 s [User: 2.704 s, System: 0.219 s]
Range (min … max): 2.910 s … 2.942 s 50 runs
when given a string yacc will copy the entire input to a newly allocated
location so that it can add a second terminating NUL byte. since the
parser is a very internal thing to EvalState we can ensure that having
two terminating NUL bytes is always possible without copying, and have
the parser itself merely check that the expected NULs are present.
# before
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 572.4 ms ± 2.3 ms [User: 563.4 ms, System: 8.6 ms]
Range (min … max): 566.9 ms … 579.1 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 381.7 ms ± 1.0 ms [User: 348.3 ms, System: 33.1 ms]
Range (min … max): 380.2 ms … 387.7 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.936 s ± 0.005 s [User: 2.715 s, System: 0.221 s]
Range (min … max): 2.923 s … 2.946 s 50 runs
# after
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 571.7 ms ± 2.4 ms [User: 563.3 ms, System: 8.0 ms]
Range (min … max): 566.7 ms … 579.7 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 376.6 ms ± 1.0 ms [User: 345.8 ms, System: 30.5 ms]
Range (min … max): 374.5 ms … 379.1 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.922 s ± 0.006 s [User: 2.707 s, System: 0.215 s]
Range (min … max): 2.906 s … 2.934 s 50 runs
speeds up parsing by ~3%, system builds by a bit more than 1%
# before
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 574.7 ms ± 2.8 ms [User: 566.3 ms, System: 8.0 ms]
Range (min … max): 569.2 ms … 580.7 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 394.4 ms ± 0.8 ms [User: 361.8 ms, System: 32.3 ms]
Range (min … max): 392.7 ms … 395.7 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.976 s ± 0.005 s [User: 2.757 s, System: 0.218 s]
Range (min … max): 2.966 s … 2.990 s 50 runs
# after
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 572.4 ms ± 2.3 ms [User: 563.4 ms, System: 8.6 ms]
Range (min … max): 566.9 ms … 579.1 ms 50 runs
Benchmark 2: nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
Time (mean ± σ): 381.7 ms ± 1.0 ms [User: 348.3 ms, System: 33.1 ms]
Range (min … max): 380.2 ms … 387.7 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.936 s ± 0.005 s [User: 2.715 s, System: 0.221 s]
Range (min … max): 2.923 s … 2.946 s 50 runs
every stringy token the lexer returns is turned into a Symbol and not
used further, so we don't have to strdup. using a string_view is
sufficient, but due to limitations of the current parser we have to use
a POD type that holds the same information.
gives ~2% on system build, 6% on search, 8% on parsing alone
# before
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 610.6 ms ± 2.4 ms [User: 602.5 ms, System: 7.8 ms]
Range (min … max): 606.6 ms … 617.3 ms 50 runs
Benchmark 2: nix eval -f hackage-packages.nix
Time (mean ± σ): 430.1 ms ± 1.4 ms [User: 393.1 ms, System: 36.7 ms]
Range (min … max): 428.2 ms … 434.2 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 3.032 s ± 0.005 s [User: 2.808 s, System: 0.223 s]
Range (min … max): 3.023 s … 3.041 s 50 runs
# after
Benchmark 1: nix search --offline nixpkgs hello
Time (mean ± σ): 574.7 ms ± 2.8 ms [User: 566.3 ms, System: 8.0 ms]
Range (min … max): 569.2 ms … 580.7 ms 50 runs
Benchmark 2: nix eval -f hackage-packages.nix
Time (mean ± σ): 394.4 ms ± 0.8 ms [User: 361.8 ms, System: 32.3 ms]
Range (min … max): 392.7 ms … 395.7 ms 50 runs
Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.976 s ± 0.005 s [User: 2.757 s, System: 0.218 s]
Range (min … max): 2.966 s … 2.990 s 50 runs
there's a few symbols in primops we can create once and pick them out of
EvalState afterwards instead of creating them every time we need them. this
gives almost 1% speedup to an uncached nix search.
there's a couple places that can be easily converted from using strings to using
string_views instead. gives a slight (~1%) boost to system eval.
# before
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.946 s ± 0.026 s [User: 2.655 s, System: 0.209 s]
Range (min … max): 2.905 s … 2.995 s 20 runs
# after
Time (mean ± σ): 2.928 s ± 0.024 s [User: 2.638 s, System: 0.211 s]
Range (min … max): 2.893 s … 2.970 s 20 runs
this avoids one copy from `s` into `str`, and possibly another copy needed to
construct `s` at the call site. lexical_cast is also more efficient in general.
constructing an ostringstream for non-string concats (like integer addition) is
a small constant cost that we can avoid. for string concats we can keep all the
string temporaries we get from coerceToString and concatenate them in one go,
which saves a lot of intermediate temporaries and copies in ostringstream. we
can also avoid copying the concatenated string again by directly allocating it
in GC memory and moving ownership of the concatenated string into the target
value.
saves about 2% on system eval.
before:
Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.837 s ± 0.031 s [User: 2.562 s, System: 0.191 s]
Range (min … max): 2.796 s … 2.892 s 20 runs
after:
Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 2.790 s ± 0.035 s [User: 2.532 s, System: 0.187 s]
Range (min … max): 2.722 s … 2.836 s 20 runs
There already existed a smoke test for the link content length,
but it appears that there exists some corruptions pernicious enough
to replace the file content with zeros, and keeping the same length.
--repair-path now goes as far as checking the content of the link,
making it true to its name and actually repairing the path for such
coruption cases.
we don't have to create an ostream sentry object for every character of a JSON
string we write. format a bunch of characters and flush them to the stream all
at once instead.
this doesn't affect small numbers of string characters, but larger numbers of
total JSON string characters written gain a lot. at 1MB of total string written
we gain almost 30%, at 16MB it's almost a factor of 3x. large numbers of JSON
string characters do occur naturally in a nixos system evaluation to generate
documentation (though this is now somewhat mitigated by caching the largest part
of nixos option docs).
benchmarked with
hyperfine 'nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) {e})"' --warmup 1 -L e 1,4,256,4096,65536
before:
Benchmark 1: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 1)"
Time (mean ± σ): 12.5 ms ± 0.2 ms [User: 9.2 ms, System: 4.0 ms]
Range (min … max): 11.9 ms … 13.1 ms 223 runs
Benchmark 2: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4)"
Time (mean ± σ): 12.5 ms ± 0.2 ms [User: 9.3 ms, System: 3.8 ms]
Range (min … max): 11.9 ms … 13.2 ms 220 runs
Benchmark 3: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 256)"
Time (mean ± σ): 13.2 ms ± 0.3 ms [User: 9.8 ms, System: 4.0 ms]
Range (min … max): 12.6 ms … 14.3 ms 205 runs
Benchmark 4: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4096)"
Time (mean ± σ): 24.0 ms ± 0.4 ms [User: 19.4 ms, System: 5.2 ms]
Range (min … max): 22.7 ms … 25.8 ms 119 runs
Benchmark 5: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 65536)"
Time (mean ± σ): 196.0 ms ± 3.7 ms [User: 171.2 ms, System: 25.8 ms]
Range (min … max): 190.6 ms … 201.5 ms 14 runs
after:
Benchmark 1: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 1)"
Time (mean ± σ): 12.4 ms ± 0.3 ms [User: 9.1 ms, System: 4.0 ms]
Range (min … max): 11.7 ms … 13.3 ms 204 runs
Benchmark 2: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4)"
Time (mean ± σ): 12.4 ms ± 0.2 ms [User: 9.2 ms, System: 3.9 ms]
Range (min … max): 11.8 ms … 13.0 ms 214 runs
Benchmark 3: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 256)"
Time (mean ± σ): 12.6 ms ± 0.2 ms [User: 9.5 ms, System: 3.8 ms]
Range (min … max): 12.1 ms … 13.3 ms 209 runs
Benchmark 4: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 4096)"
Time (mean ± σ): 15.9 ms ± 0.2 ms [User: 11.4 ms, System: 5.1 ms]
Range (min … max): 15.2 ms … 16.4 ms 171 runs
Benchmark 5: nix eval --raw --expr "let s = __concatStringsSep \"\" (__genList (_: \"c\") 256); in __toJSON (__genList (_: s) 65536)"
Time (mean ± σ): 69.0 ms ± 0.9 ms [User: 44.3 ms, System: 25.3 ms]
Range (min … max): 67.2 ms … 70.9 ms 42 runs
Previously you had to remember to call value->attrs->sort() after
populating value->attrs. Now there is a BindingsBuilder helper that
wraps Bindings and ensures that sort() is called before you can use
it.
nixpkgs can save a good bit of eval memory with this primop. zipAttrsWith is
used quite a bit around nixpkgs (eg in the form of recursiveUpdate), but the
most costly application for this primop is in the module system. it improves
the implementation of zipAttrsWith from nixpkgs by not checking an attribute
multiple times if it occurs more than once in the input list, allocates less
values and set elements, and just avoids many a temporary object in general.
nixpkgs has a more generic version of this operation, zipAttrsWithNames, but
this version is only used once so isn't suitable for being the base of a new
primop. if it were to be used more we should add a second primop instead.
When we check for disappeared overrides, we can get "false positives"
for follows and overrides which are defined in the dependencies of the
flake we are locking, since they are not parsed by
parseFlakeInputs. However, at that point we already know that the
overrides couldn't have possible been changed if the input itself
hasn't changed (since we check that oldLock->originalRef == *input.ref
for the input's parent). So, to prevent this, only perform this check
when it was possible that the flake changed (e.g. the flake we're
locking, or a new input, or the input has changed and mustRefetch ==
true).
This makes sure that values parsed from TOML have a proper size. Using
e.g. `double` caused issues on i686 where the size of `double` (32bit)
was too small to accommodate some values.
This was already accidentally disabled in ba87b08. It also no longer
appears to be beneficial, and in fact slow things down, e.g. when
evaluating a NixOS system configuration:
elapsed time: median = 3.8170 mean = 3.8202 stddev = 0.0195 min = 3.7894 max = 3.8600 [rejected, p=0.00000, Δ=0.36929±0.02513]
calling GC_malloc for each value is significantly more expensive than
allocating a bunch of values at once with GC_malloc_many. "a bunch" here
is a GC block size, ie 16KiB or less.
this gives a 1.5% performance boost when evaluating our nixos system.
tested with
nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
# on master
Time (mean ± σ): 3.335 s ± 0.007 s [User: 2.774 s, System: 0.293 s]
Range (min … max): 3.315 s … 3.347 s 50 runs
# with this change
Time (mean ± σ): 3.288 s ± 0.006 s [User: 2.728 s, System: 0.292 s]
Range (min … max): 3.274 s … 3.307 s 50 runs
Add a `_NIX_TRACE_BUILT_OUTPUTS` environment variable that can be set to
a filename in which the result of each build will be logged.
This is intentionally crude and undocumented as it’s only meant to be a
temporary thing to assess the usefulness of CA derivations.
Any other use would need a cleaner re-implementation first.
Make the build of unresolved derivations return the same status as the
resolved one, except in the case of an `AlreadyValid` in which case it
will return `ResolvesToAlreadyValid` to mean that the outputs of the unresolved
derivation weren’t known, but the resolved one is.
When a variable is assigned in the REPL, make sure to remove any possible reference to the old one so that we correctly pick the new one afterwards
Fix#5706
I downloaded Nix tonight, and immediately broke it by accidentally removing the default binary caching.
After figuring this out, I also failed to fix it properly, due to using the wrong key for Nix's default binary cache
If the diagnostic message would have been clearer about what/where a "signature" for a "substituter" is + comes from, it probably would have saved me a few hours.
Maybe we can save other noobs the same pain?
Before this change, stdout was closed after the pager exits. This is
fine for non-interactive commands where we want to exit right after
the pager exits anyways, but for interactive things (e.g. nix repl)
this breaks the output after we quit the pager.
Keep the initial stdout fd as part of RunPager, and restore it in
RunPager::~RunPager using dup2.
This function is very useful in nixpkgs, but its implementation in Nix
itself is rather slow due to it requiring a lot of attribute set and
list appends.
Previously, when we were attempting to reuse the old lockfile
information in the computeLocks function, we have passed the parent of
the current input to the next computeLocks call. This was incorrect,
since the follows are resolved relative to the parent. This caused
issues when we tried to reuse oldLock but couldn't for some
reason (read: mustRefetch is true), in that case the follows were
resolved incorrectly.
Fix this by passing the correct parent, and adding some tests to
prevent this particular regression from happening again.
Closes https://github.com/NixOS/nix/issues/5697
- Previous to this commit the boundary was exclusive of the
top level flake.
- This is wrong since the top level flake is still a valid
relative reference.
- Now, the check boundary is inclusive of the top level flake.
Signed-off-by: Timothy DeHerrera <tim.deh@pm.me>
Due to missing <atomic> declaration the build fails as:
src/libutil/util.hh:350:24: error: no match for 'operator||' (operand types are 'std::atomic<bool>' and 'bool')
350 | if (_isInterrupted || (interruptCheck && interruptCheck()))
| ~~~~~~~~~~~~~~ ^~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| std::atomic<bool> bool
Because the manual is generated from default values which are themselves
generated from various sources (cpuid, bios settings (kvm), number of
cores). This commit hides non-reproducible settings from the manual
output.
No matter what, we need to resize the buffer to not have any scratch
space after we do the `read`. In the end of file case, `got` will be 0
from it's initial value.
Before, we forgot to resize in the EOF case with the break. Yes, we know
we didn't recieve any data in that case, but we still have the scatch
space to undo.
Co-Authored-By: Will Fancher <Will.Fancher@Obsidian.Systems>
This doesn't fix the bug, but makes the code less difficult to read.
Also improve the comments, now that it is clear what part is needed in
each code path.
Moving arguments of the primOp into the registration structure makes it
impossible to initialize a second EvalState with the correct primOp
registration. It will end up registering all those "RegisterPrimOp"'s
with an arity of zero on all but the 2nd instance of the EvalState.
Not moving the memory will add a tiny bit of memory overhead during the
eval since we need a copy of all the argument lists of all the primOp's.
The overhead shouldn't be too bad as it is static (based on the amonut
of registered operations) and only occurs once during the interpreter
startup.
If we’re in pure eval mode, then tell that in the error message rather
than (wrongly) speaking about restricted mode.
Fix https://github.com/NixOS/nix/issues/5611
We let DISPLAY (X11) through, so we should let the Wayland equivalents
through as well. Similarly, we let HOME through, so it should be okay
to allow XDG_RUNTIME_DIR (which is needed for connecting to Wayland
with WAYLAND_DISPLAY) through as well. Otherwise graphical
applications will either fall back to X11 (if they support it), or
just not work (if they don't).
This is not really useful on its own, but it does recover the
'infinite recursion' error message for '{ __functor = x: x; } 1', and
is more efficient in conjunction with #3718.
Fixes#5515.
- This change applies to builtins.toXML and inner workings
- Proof of concept:
```nix
let e = builtins.toXML e; in e
```
- Before:
```
$ nix-instantiate --eval poc.nix
error: infinite recursion encountered
```
- After:
```
$ nix-instantiate --eval poc.nix
error: infinite recursion encountered
at /data/github/kamadorueda/nix/poc.nix:1:9:
1| let e = builtins.toXML e; in e
|
```
These headers are included by the libexpr, libfetchers, libstore
and libutil headers.
Considering that these are vendored sources, Nix should expose them,
as it is not a good idea for reverse dependencies to rely on a
potentially different source that can go out of sync.
When an input follows disappears, we can't just reuse the old lock
file entries since we may be missing some required ones. Refetch the
input when this happens.
Closes https://github.com/NixOS/nix/issues/5289
For a typical desktop system (~2K packages) we can easily get 100K
entries in RealisationsRefs. Without indices query for RealisationsRefs
requires linear scan.
RealisationsRefs(referrer)
--------------------------
Inefficiency is seen as a 100% CPU load of nix-daemon for the following
scenario:
$ nix edit -f . bash # add unused environment variable, like FOO="1"
# populate RealisationsRefs, build fresh system
$ nix build -f nixos system --arg config '{ contentAddressedByDefault = true; }'
$ nix edit -f . bash # add unused environment variable, like FOO="2"
$ time nix build -f nixos system --arg config '{ contentAddressedByDefault = true; }'
In this case `bash `will be rebuilt a few times and then rest of CPU
time is spent on scanning RealisationsRefs table (about 5 CPU-minutes
on my machine).
Before the change:
$ time nix build -f nixos system ... # step 4 above
real 34m3,613s
user 0m5,232s
sys 0m0,758s
Of all this time about 29.5 minutes are taken by nix-daemon's CPU time.
After the change:
$ time nix build -f nixos system ... # step 4 above
real 4m50,061s
user 0m5,038s
sys 0m0,677s
Of all this time about 1 minute is taken by nix-daemon's CPU time.
Most of the time is spent polling for non-existent realisations on
cache-nixos.org.
Realisations(outputPath)
------------------------
After running CA system for two weeks I got ~1M entries in Realisations
table. `nix-collect-garbage` became very slow (seemingly 100 path deletions
per second). It happens due to a slow cascading delete from Realisations
triggered by deletion from ValidPaths.
The fix is to add an index on primary key from ValidPaths(id) that
triggers cascading deletions.
Before the change:
$ time nix-collect-garbage -d --max-freed 100G
<interrupted before finish, took too long>
real 23m32.411s
user 17m49.679s
sys 4m50.609s
Most of time was spent in re-scanning Realisations table on each path deletion.
After the change:
$ time nix-collect-garbage -d --max-freed 100G
real 8m43.226s
user 6m16.317s
sys 1m40.188s
Time is spent scanning sqlite indices and in kernel when unlinking directories.
Doing it as a side-effect of calling LocalStore::makeStoreWritable()
is very ugly.
Also, make sure that stopping the progress bar joins the update
thread, otherwise that thread should be unshared as well.
Since 4806f2f6b0, we can't have paths with
references passed to builtins.{path,filterSource}. This prevents many cases
of those functions called on IFD outputs from working. Resolve this by
passing the references found in the original path to the added path.
When setting flake-local options (with the `nixConfig` field), forward
these options to the daemon in case we’re using one.
This is necessary in particular for options like `binary-caches` or
`post-build-hook` to make sense.
Fix <343239fc8a (r44356843)>
When running a `:b` command in the repl, after building the derivations
query the store for its outputs rather than just assuming that they are
known in the derivation itself (which isn’t true for CA derivations)
Fix#5328
We now parse function applications as a vector of arguments rather
than as a chain of binary applications, e.g. 'substring 1 2 "foo"' is
parsed as
ExprCall { .fun = <substring>, .args = [ <1>, <2>, <"foo"> ] }
rather than
ExprApp (ExprApp (ExprApp <substring> <1>) <2>) <"foo">
This allows primops to be called immediately (if enough arguments are
supplied) without having to allocate intermediate tPrimOpApp values.
On
$ nix-instantiate --dry-run '<nixpkgs/nixos/release-combined.nix>' -A nixos.tests.simple.x86_64-linux
this gives a substantial performance improvement:
user CPU time: median = 0.9209 mean = 0.9218 stddev = 0.0073 min = 0.9086 max = 0.9340 [rejected, p=0.00000, Δ=-0.21433±0.00677]
elapsed time: median = 1.0585 mean = 1.0584 stddev = 0.0024 min = 1.0523 max = 1.0623 [rejected, p=0.00000, Δ=-0.20594±0.00236]
because it reduces the number of tPrimOpApp allocations from 551990 to
42534 (i.e. only small minority of primop calls are partially
applied) which in turn reduces time spent in the garbage collector.
Rather than having them plain strings scattered through the whole
codebase, create an enum containing all the known experimental features.
This means that
- Nix can now `warn` when an unkwown experimental feature is passed
(making it much nicer to spot typos and spot deprecated features)
- It’s now easy to remove a feature altogether (once the feature isn’t
experimental anymore or is dropped) by just removing the field for the
enum and letting the compiler point us to all the now invalid usages
of it.
Currently machine specification (`/etc/nix/machine`) parser fails
with a vague exception if the file had incorrect format.
This commit adds verbose exceptions and unit-tests for the parser.
Fixed a bug in initialization of 'base64DecodeChars' variable.
Currently decoder do not fail on invalid Base64 strings.
Added test-case to verify the fix.
Also have made 'base64DecodeChars' to be computed at compile time.
And added a test case to encode/decode string with non-printable charactes.
- This way we improve error messages
on infinite recursion
- Demo:
```nix
let x = builtins.fetchTree x;
in x
```
- Before:
```bash
$ nix-instantiate --extra-experimental-features flakes --strict
error: infinite recursion encountered
```
- After:
```bash
$ nix-instantiate --extra-experimental-features flakes --strict
error: infinite recursion encountered
at /data/github/kamadorueda/nix/test.nix:1:9:
1| let x = builtins.fetchTree x;
| ^
2| in x
```
Mentions: #3505
This ensures any started processes can't write to /nix/store (except
during builds). This partially reverts 01d07b1e, which happened because
of #2646.
The problem was only happening after nix downloads anything, causing
me to suspect the download thread. The problem turns out to be:
"A process can't join a new mount namespace if it is sharing
filesystem-related attributes with another process", in this case this
process is the curl thread.
Ideally, we might kill it before spawning the shell process, but it's
inside a static variable in the getFileTransfer() function. So
instead, stop it from sharing FS state using unshare(). A strategy
such as the one from #5057 (single-threaded chroot helper binary) is
also very much on the table.
Fixes#4337.
- This way we improve error messages
on infinite recursion
- Demo:
```nix
let
x = builtins.fetchMercurial x;
in
x
```
- Before:
```bash
$ nix-instantiate --show-trace --strict
error: infinite recursion encountered
```
- After:
```bash
nix-instantiate --show-trace --strict
error: infinite recursion encountered
at /data/github/kamadorueda/test/default.nix:2:7:
1| let
2| x = builtins.fetchMercurial x;
| ^
3| in
```
Mentions: #3505
We can actually just load nss ourselves and call in nss to configure it
and we don't need to run a dummy query entirely to have nss load nss_dns
as a side-effect.
Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
This fixes a bug in the garbage collector where if a path
/nix/store/abcd-foo is valid, but we do a
isValidPath("/nix/store/abcd-foo.lock") first, then a negative entry
for /nix/store/abcd is added to pathInfoCache, so /nix/store/abcd-foo
is subsequently considered invalid and deleted.
