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pennae 5838354d34 optimize ExprConcatStrings::eval
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
2022-01-12 10:07:21 +01:00
.github add pull_request_template.md 2021-12-09 14:31:34 -05:00
config Run autoupdate 2021-06-01 11:42:38 +02:00
contrib function-trace: always show the trace 2019-09-18 23:23:21 +02:00
doc/manual add zipAttrsWith primop 2022-01-03 21:05:53 +01:00
m4 autoconf: Fix C++17 detection not working on Ubuntu 16.04. 2019-07-03 04:32:25 +02:00
maintainers Update release script 2021-11-02 11:53:25 +01:00
misc Merge pull request #5820 from ncfavier/completion-nospace 2021-12-22 17:55:05 +01:00
mk mk/libraries.mk: fix trace-ld and trace-ar expansions 2021-10-08 22:59:42 +01:00
nix-rust Apply OS checks to host platform, not build 2021-06-23 15:00:36 +00:00
perl Document libsodium, which is now mandatory, as a dependency 2021-11-27 23:11:11 +01:00
scripts Merge pull request #5521 from abathur/clearly_mark_validation_step 2021-12-08 20:04:03 +00:00
src optimize ExprConcatStrings::eval 2022-01-12 10:07:21 +01:00
tests Merge pull request #5546 from NixOS/allow-paths-in-flake-local-options 2022-01-06 21:55:20 +01:00
.dir-locals.el .dir-locals.el: Set c-block-comment-prefix 2020-07-10 11:21:06 +02:00
.editorconfig Add .editorconfig 2017-06-05 22:57:28 +01:00
.gitignore Remove nix-reduce-build and nix-http-export 2021-11-18 21:17:57 +01:00
.version Bump version 2021-12-14 00:01:42 +01:00
boehmgc-coroutine-sp-fallback.diff Fix leaking pthread_attr_t 2021-11-03 22:54:16 +01:00
bootstrap.sh bootstrap: Simplify & make more robust. 2011-09-06 12:11:05 +00:00
configure.ac Merge pull request #5678 from t184256/document-libsodium 2021-11-29 11:11:10 +01:00
COPYING * Change this to LGPL to keep the government happy. 2006-04-25 16:41:06 +00:00
default.nix Simplify shell.nix and default.nix 2020-06-17 19:21:46 +02:00
docker.nix Add iana-etc for /etc/protocols to default packages 2022-01-04 12:49:02 +01:00
flake.lock Revert "update flake.nix to 21.11" 2021-12-15 13:49:05 +01:00
flake.nix Make bash completion for 'nix' work in a devshell 2021-12-22 13:21:45 +01:00
local.mk Remove 'dist' target 2020-12-03 16:17:58 +01:00
Makefile Install nlohmann_json headers 2021-11-11 11:05:44 +01:00
Makefile.config.in Apply OS checks to host platform, not build 2021-06-23 15:00:36 +00:00
precompiled-headers.h Config: Use nlohmann/json 2020-08-20 11:02:16 +02:00
README.md throw freenode down the memory hole 2021-05-27 21:48:39 +02:00
shell.nix Add back flake-compat shell.nix 2020-07-17 14:58:59 +00:00

Nix

Open Collective supporters Test

Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. Please refer to the Nix manual for more details.

Installation

On Linux and macOS the easiest way to install Nix is to run the following shell command (as a user other than root):

$ curl -L https://nixos.org/nix/install | sh

Information on additional installation methods is available on the Nix download page.

Building And Developing

See our Hacking guide in our manual for instruction on how to build nix from source with nix-build or how to get a development environment.

Additional Resources

License

Nix is released under the LGPL v2.1.