Previous code had a sneaky bug due to which no caching
actually happened:
```cpp
auto linesForInput = (*lines)[origin->offset];
```
That should have been:
```cpp
auto & linesForInput = (*lines)[origin->offset];
```
See [1].
Now that it also makes sense to make the cache bound in side
in order not to memoize all the sources without freeing any memory.
The default cache size has been chosen somewhat arbitrarily to be ~64k
origins. For reference, 25.05 nixpkgs has ~50k .nix files.
Simple benchmark:
```nix
let
pkgs = import <nixpkgs> { };
in
builtins.foldl' (acc: el: acc + el.line) 0 (
builtins.genList (x: builtins.unsafeGetAttrPos "gcc" pkgs) 10000
)
```
(After)
```
$ hyperfine "result/bin/nix eval -f ./test.nix"
Benchmark 1: result/bin/nix eval -f ./test.nix
Time (mean ± σ): 292.7 ms ± 3.9 ms [User: 131.0 ms, System: 120.5 ms]
Range (min … max): 288.1 ms … 300.5 ms 10 runs
```
(Before)
```
hyperfine "nix eval -f ./test.nix"
Benchmark 1: nix eval -f ./test.nix
Time (mean ± σ): 666.7 ms ± 6.4 ms [User: 428.3 ms, System: 191.2 ms]
Range (min … max): 659.7 ms … 681.3 ms 10 runs
```
If the origin happens to be a `all-packages.nix` or similar in size then the
difference is much more dramatic.
[1]: 22e3f0e987
As summarized in
https://github.com/NixOS/nix/issues/77#issuecomment-2843228280 the
motivation is that the complicated retry logic this introduced was
making the cleanup task #12628 harder to accomplish. It was not easy to
ascertain just what policy / semantics the extra control-flow was
implementing, in order to figure out a different way to implementing it
either.
After talking to Eelco about it, he decided we could just....get rid of
the feature entirely! It's a bit scary removing a decade+ old feature,
but I think he is right. See the release notes for more explanation.
This reverts commit 299141ecbd.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Leverage #10766 to show how we can now resolve a store configuration
without actually opening the store for that resolved configuration.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Splicing the list element to the back can be done in
a much simpler and concise way without the need for
erasing and re-inserting the element. Doing it this
way is equivalent to just moving node pointers around,
whereas inserting/erasing allocates/deallocates new nodes.
This renders the rl-next notes when `officialRelease = false`, which
corresponds to the case where we're not on a release branch.
Previously we had disabled this behavior because changelog-d is
somewhat of a heavy dependency, being the only Haskell package.
However, we now have new circumstances that topple the tradeoff.
- We render `master` docs to https://nix.dev/manual/nix/development/release-notes/rl-next.html
- `.#manual` is a separate build now, so `nix build nix/foo` is
not affected by the increased closure of build input outputs.
Because of these factors, I believe adding this functionality back
is more valuable, as we can use it to
- Previous release notes
- Showcase the upcoming release to the community
