For example, instead of doing
#include "nix/store-config.hh"
#include "nix/derived-path.hh"
Now do
#include "nix/store/config.hh"
#include "nix/store/derived-path.hh"
This was originally planned in the issue, and also recent requested by
Eelco.
Most of the change is purely mechanical. There is just one small
additional issue. See how, in the example above, we took this
opportunity to also turn `<comp>-config.hh` into `<comp>/config.hh`.
Well, there was already a `nix/util/config.{cc,hh}`. Even though there
is not a public configuration header for libutil (which also would be
called `nix/util/config.{cc,hh}`) that's still confusing, To avoid any
such confusion, we renamed that to `nix/util/configuration.{cc,hh}`.
Finally, note that the libflake headers already did this, so we didn't
need to do anything to them. We wouldn't want to mistakenly get
`nix/flake/flake/flake.hh`!
Progress on #7876
There are two big changes:
1. Public and private config is now separated. Configuration variables
that are only used internally do not go in a header which is
installed.
(Additionally, libutil has a unix-specific private config header,
which should only be used in unix-specific code. This keeps things a
bit more organized, in a purely private implementation-internal way.)
2. Secondly, there is no more `-include`. There are very few config
items that need to be publically exposed, so now it is feasible to
just make the headers that need them just including the (public)
configuration header.
And there are also a few more small cleanups on top of those:
- The configuration files have better names.
- The few CPP variables that remain exposed in the public headers are
now also renamed to always start with `NIX_`. This ensures they should
not conflict with variables defined elsewhere.
- We now always use `#if` and not `#ifdef`/`#ifndef` for our
configuration variables, which helps avoid bugs by requiring that
variables must be defined in all cases.
The short answer for why we need to do this is so we can consistently do
`#include "nix/..."`. Without this change, there are ways to still make
that work, but they are hacky, and they have downsides such as making it
harder to make sure headers from the wrong Nix library (e..g.
`libnixexpr` headers in `libnixutil`) aren't being used.
The C API alraedy used `nix_api_*`, so its headers are *not* put in
subdirectories accordingly.
Progress on #7876
We resisted doing this for a while because it would be annoying to not
have the header source file pairs close by / easy to change file
path/name from one to the other. But I am ameliorating that with
symlinks in the next commit.
- Some headers were completely redundant and have been removed.
- Other headers have been turned private.
- Unnecessary meson.build code has been removed.
- libutil-tests now has a private config header, where previously
it had none. This removes the need to expose a package version
macro publicly.
Before the change "illegal reference" was hard to interpret as it did
not mention what derivation actually hits it.
Today's `nixpkgs` example:
Before the change:
$ nix build --no-link -f. postgresql_14
...
error: derivation contains an illegal reference specifier 'man'
After the change:
$ nix build --no-link -f. postgresql_14
...
error: derivation '/nix/store/bxp6g57limvwiga61vdlyvhy7i8rp6wd-postgresql-14.15.drv' output check for 'lib' contains an illegal reference specifier 'man', expected store path or output name (one of [debug, dev, doc, lib, out])
Instead of calling `worker.waitForAWhile(shared_from_this())` etc.,
the subclasses of Goal instead call protected functions defined in Goal
that abstract over these.
The code for awaiting has also been heavily simplified.
Instead of calling `addWaitee`, then suspending,
`co_await await(waitees)` is called once, which also handles the suspend.
The end-goal is to remove all manual `co_await Suspend{}`s.
Now that we have coroutines, we can go back to loops and regular RAII,
which is must less error-proone!
I look forward to removing the other instances!
Perhaps more significantly, it no longer knows about
`LocalDerivationGoal`, and without any effort it also compiles on
Windows just fine. (`local-derivation-goal.{cc,hh}` is currently skipped
on Windows.)
The simplification here is due to a long-standing bug, but it is not
worth fixing the bug at this time. Instead we've finally written up an
issue for the bug, and referenced the issue number in the code.
In the local building case, there is many things which can through
`BuildError`, but in the hook case there is just this one. We can
therefore simplify the code by "cinching" down the logic just to the
spot the error is thrown.
There is other code outside `libstore/build` which also uses
`BuildError`, but I believe those cases are mistakes. The point of
`BuildError` is the narrow technical use-cases of "errors which should
not be fatal with `--keep-going`". Using it outside the
building/scheduling code doesn't really make sense in that regard. It
seems likely that those usages were instead merely because "oh, this
error has something to do with building, so I guess `BuildError` is
better than `Error`".
It is quite likely that I myself used `BuildError` incorrectly as
described above :).
The variables are only set by CGroup mechanisms in `killSandbox` in the
local build. In the build hook case, these variables will not be set, so
there is nothing to do.
We can move this method from `LocalStore` to `Store` --- even if we only
want the actual builder to sign things in many cases, there is no reason
to try to enforce this policy by spurious moving the method to a
subclass.
Now, we might technically sign class, but CA derivations is
experimental, and @Ericson2314 is going to revisit all this stuff with
issue #11896 anyways.
- `chrootParentDir` can be a local variable instead of a class variable.
- `getChildStatus` can be inlined. Again, we have the `assert(!hook);`
in the local building case, which makes for a simpler thing inlined.
Thanks to the previous commit, we can inline all these small callbacks.
In the build-hook case, they were empty, and now they disappear
entirely.
While `LocalDerivationGoal` can be used in the hook case (we use it
based on whether we have a local store, not based on whether we are
using the build hook, a decision which comes later), the previous
commit's inline moved the code into a spot where we know we are cleaning
up after local building, *not* after running the build hook. This allows
for much more simplification.
The basic idea is that while we have duplicated this function, we now
have one call-site in the local build case, and one call site in the
build hook case. This unlocks big opportunities to specialize each copy,
since they really shouldn't be doing the same things. By the time we are
are done, there should not be much duplication left.
See #12628 for further info.
