since `up` and `values` are both pointer-aligned the type field will
also be pointer-aligned, wasting 48 bits of space on most machines. we
can get away with removing the type field altogether by encoding some
information into the `with` expr that created the env to begin with,
reducing the GC load for the absolutely massive amount of single-entry
envs we create for lambdas. this reduces memory usage of system eval by
quite a bit (reducing heap size of our system eval from 8.4GB to 8.23GB)
and gives similar savings in eval time.
running `nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'`
before:
Time (mean ± σ): 5.576 s ± 0.003 s [User: 5.197 s, System: 0.378 s]
Range (min … max): 5.572 s … 5.581 s 10 runs
after:
Time (mean ± σ): 5.408 s ± 0.002 s [User: 5.019 s, System: 0.388 s]
Range (min … max): 5.405 s … 5.411 s 10 runs
a bunch of derivation strings contain no escape sequences. we can
optimize for this fact by first scanning for the end of a derivation
string and simply returning the contents unmodified if no escape
sequences were found. to make this even more efficient we can also use
BackedStringViews to avoid copies, avoiding heap allocations for
transient data.
before:
Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 6.952 s ± 0.015 s [User: 5.294 s, System: 1.452 s]
Range (min … max): 6.926 s … 6.974 s 10 runs
after:
Benchmark 1: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
Time (mean ± σ): 6.907 s ± 0.012 s [User: 5.272 s, System: 1.429 s]
Range (min … max): 6.893 s … 6.926 s 10 runs
This fixes a segfault on infinite function call recursion (rather than
infinite thunk recursion) by tracking the function call depth in
`EvalState`.
Additionally, to avoid printing extremely long stack traces, stack
frames are now deduplicated, with a `(19997 duplicate traces omitted)`
message. This should only really be triggered in infinite recursion
scenarios.
Before:
$ nix-instantiate --eval --expr '(x: x x) (x: x x)'
Segmentation fault: 11
After:
$ nix-instantiate --eval --expr '(x: x x) (x: x x)'
error: stack overflow
at «string»:1:14:
1| (x: x x) (x: x x)
| ^
$ nix-instantiate --eval --expr '(x: x x) (x: x x)' --show-trace
error:
… from call site
at «string»:1:1:
1| (x: x x) (x: x x)
| ^
… while calling anonymous lambda
at «string»:1:2:
1| (x: x x) (x: x x)
| ^
… from call site
at «string»:1:5:
1| (x: x x) (x: x x)
| ^
… while calling anonymous lambda
at «string»:1:11:
1| (x: x x) (x: x x)
| ^
… from call site
at «string»:1:14:
1| (x: x x) (x: x x)
| ^
(19997 duplicate traces omitted)
error: stack overflow
at «string»:1:14:
1| (x: x x) (x: x x)
| ^
Previously, IFDs would be built within the eval store, even though one
is typically using `--eval-store` precisely to *avoid* local builds.
Because the resulting Nix expression must be copied back to the eval
store in order to be imported, this requires the eval store to trust
the build store's signatures.
It might seem obnoxious to have yet more configure flags, but I found
controlling both the unit and functional tests with one flag was quite
confusing because they are so different:
- unit tests depending on building, functional tests don't (e.g. when
we test already-built Nix)
- unit tests can be installed, functional tests cannot
- unit tests neeed extra libraries (GTest, RapidCheck), functional
tests need extra executables (jq).
- unit tests are run by `make check`, functional tests are run by `make
installcheck`
Really on a technical level, they seem wholly independent. Only on a
human level ("they are both are tests") do they have anything in common.
I had messed up the logic in cross builds because of this. Now I
split the flag in two (and cleaned up a few other inconsistencies), and
the logic fixed itself.
Co-Authored-By: Robert Hensing <roberth@users.noreply.github.com>
* document `fetchTree`
* display experimental feature note at the top
we have to enable the new `fetchTree` experimental feature to render it
at all. this was a bug introduced when adding that new feature flag.
Co-authored-by: tomberek <tomberek@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Silvan Mosberger <github@infinisil.com>
* Print the value in `error: cannot coerce` messages
This extends the `error: cannot coerce a TYPE to a string` message
to print the value that could not be coerced. This helps with debugging
by making it easier to track down where the value is being produced
from, especially in errors with deep or unhelpful stack traces.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This includes position information in more places, making debugging
easier.
Before:
```
$ nix-instantiate --show-trace --eval tests/functional/lang/eval-fail-using-set-as-attr-name.nix
error:
… while evaluating an attribute name
at «none»:0: (source not available)
error: value is a set while a string was expected
```
After:
```
error:
… while evaluating an attribute name
at /pwd/lang/eval-fail-using-set-as-attr-name.nix:5:10:
4| in
5| attr.${key}
| ^
6|
error: value is a set while a string was expected
```
Today, with the tests inside a `tests` intermingled with the
corresponding library's source code, we have a few problems:
- We have to be careful that wildcards don't end up with tests being
built as part of Nix proper, or test headers being installed as part
of Nix proper.
- Tests in libraries but not executables is not right:
- It means each executable runs the previous unit tests again, because
it needs the libraries.
- It doesn't work right on Windows, which doesn't want you to load a
DLL just for the side global variable . It could be made to work
with the dlopen equivalent, but that's gross!
This reorg solves these problems.
There is a remaining problem which is that sibbling headers (like
`hash.hh` the test header vs `hash.hh` the main `libnixutil` header) end
up shadowing each other. This PR doesn't solve that. That is left as
future work for a future PR.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This makes for more useful manual table of contents, that displays the
information at a glance.
The `nix help-stores` command is kept as-is, even though it will show up
in the manual with the same information as these pages due to the way it
is written as a "`--help`-style" command. Deciding what to do with that
command is left for a later PR.
This change also lists all store types at the top of the respective overview page.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems
this focuses on `nix-shell -p` and refers to search.nixos.org for
package search, which is currently the easiest and most effective way to
find program names.
- put the highlight box around all the relevant instructions
- simplify the wording
- make the link more prominent by using the whole phrase for the link text
- helps navigating the code as it highlights which files are generated
- makes it less error prone when working incrementally
(although this should be just fixed by building out of tree)
Previously many of the documentation targets were depending on
`$(bindir)/nix` which is the installed version. This meant that its
install rules would be triggered (which in chain would also trigger the
install of libraries, as reported in #5140). Therefore a build of the
documentation without an installation would not be possible (which apart
from doing unwanted operations it may also generate permission problems
for example).
The fix makes the rules depend on `$(nix_PATH)` instead, which is the
executable in the build tree.
`installcheck` doesn't yet work, but the rest of the build can now
happen mostly inside a separate build directory.
Progress on #9342
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
up to now, those were managed outside of this repo, which as
unsurprisingly a real hassle to deal with if one wanted to prevent URLs
from breaking when moving pages around. this change removes a large part
of the friction involved in moving content in the Nix manual.
possible next steps for further automation:
- check for content that moved and warn if it's not reachable from
links that were valid prior to a change
- create redirect rules automatically based on this information
nix-repl> bools = [ false true ]
nix-repl> combinations = builtins.concatMap (a: builtins.concatMap (b: map (c: { inherit a b c; }) bools) bools) bools
nix-repl> builtins.all ({ a, b, c }: (a -> b -> c) == (a -> (b -> c))) combinations
true
nix-repl> builtins.all ({ a, b, c }: (a -> b -> c) == ((a -> b) -> c)) combinations
false
The basic idea here is to separate a few intertwined notions:
1. Not all "run bash tests" are "install tests"
2. Not all "run bash tests" use `tests/functional/init.sh`, or any
pre-test initialization at all.
This will used in the next commit when we have a test that check unit
test golden master data.
Also, move our custom `PS4` from the test to the test runner, as it is
part of how we want to display the tests, not the test themselves.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
As discussed in our last meeting, we need a bit more time, but we are
"time boxing" the work left to do to ensure there is not unbounded
delay.
Rather than putting it back underneath `flakes`, though, put it
underneath its own `fetch-tree` experimental feature (which `flakes`
includes/implies). This signals our commitment to the plan to stabilize
it first without waiting to go through the rest of Flakes, and also will
give users a "release candidate" when we get closer to stabilization.
This reverts commit 4112dd1fc9.
Before it returned a list of JSON objects with store object information,
including the path in each object. Now, it maps the paths to JSON
objects with the metadata sans path.
This matches how `nix derivation show` works.
Quite hillariously, none of our existing functional tests caught this
change to `path-info --json` though they did use it. So just new
functional tests need to be added.
This adds publicKeys as an optional fetcher input attribute to flakes
and builtins.fetchGit to provide a nix interface for the json-encoded
`publicKeys` attribute of the git fetcher.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
update the glossary to point to the new page.
since this is a cross-cutting concern, it warrants its own section in
the manual.
Co-authored-by: John Ericson <git@JohnEricson.me>
* document the store concept and its purpose
reword the glossary to link to more existing information instead of
repeating it.
move the store documentation to the top of the table of contents, in
front of the Nix language. this will provide a natural place to
document other aspects of the store as well as the various store types.
move the package management section after the Nix language and before
Advanced Topics to follow the pattern to layer more complex concepts on
top of each other.
this structure of the manual will also nudge beginners to learn Nix
bottom-up and hopefully make more likely that they understand underlying
concepts first before delving into complex use cases that may or may not
be easy to implement with what's currently there.
[John adds this note] The sort of beginner who likes to dive straight into reference documentation should prefer this approach. Conversely, the sort of beginner who would prefer the opposite top-down approach of trying to solve problems before they understand everything that is going on is better off reading other tutorial/guide material anyways, and will just "random-access" the reference manual as a last resort. For such random-access the order doesn't matter, so this restructure doesn't make them any worse off.
Co-authored-by: John Ericson <git@JohnEricson.me>
Rather than having a misc tutorial page in the grab-bag "package management" section, this information should just be part of the S3 store docs.
---------
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
Single quotes are a basic feature of shell syntax that people expect to
work. They are also more convenient for writing literal code expressions
with less escaping.
this is the first thing most beginners see, and it misleads them into
assuming `nix-env` is appropriate for doing anything but setting and
reverting profile generations.
this chapter is the root of most evil around the ecosystem, and today we
finally close it for good.
* docker: publish images to ghcr.io
docker.com announced their intention to remove the free plan used by
OSS. The nixos/nix image is essential to various CI runs to build with
nix. To provide a continuity plan, this commit pushes the image to
ghcr.io as well.
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
