2400191caf
Back in 2013, update-mime-database started using fdatasync() to write out its changes after processing each file in /share/mime, with the reasoning that a corrupted database from an interruption midway would be problematic for applications[1]. Unfortunately, this caused a significant regression in the time required to run update-mime-database: commonly from under a second to half a minute or more. This delay affects the time required to build system-path on NixOS, when xdg.mime.enable is true (the default). For example, on one of my systems system-path builds in ~48 seconds, 45 of which are update-mime-database. This makes rapidly building new system configurations not fun. This commit disables the calls to fdatasync(). update-mime-database checks an environment variable, PKGSYSTEM_ENABLE_FSYNC, to determine whether it should sync, and we can set this to false. system-path already only has whatever filesystem commit guarantees that the Nix builder provides. Furthermore, there is no risk of a failed MIME database update messing up existing packages, because this is Nix. (This issue was also reported at and discussed by Debian, Red Hat, and Gentoo at least.) [1] https://bugs.freedesktop.org/show_bug.cgi?id=70366
36 lines
1.2 KiB
Nix
36 lines
1.2 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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{
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options = {
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xdg.mime.enable = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Whether to install files to support the
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<link xlink:href="https://specifications.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-latest.html">XDG Shared MIME-info specification</link> and the
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<link xlink:href="https://specifications.freedesktop.org/mime-apps-spec/mime-apps-spec-latest.html">XDG MIME Applications specification</link>.
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'';
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};
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};
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config = mkIf config.xdg.mime.enable {
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environment.pathsToLink = [ "/share/mime" ];
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environment.systemPackages = [
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# this package also installs some useful data, as well as its utilities
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pkgs.shared-mime-info
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];
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environment.extraSetup = ''
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if [ -w $out/share/mime ] && [ -d $out/share/mime/packages ]; then
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XDG_DATA_DIRS=$out/share PKGSYSTEM_ENABLE_FSYNC=0 ${pkgs.buildPackages.shared-mime-info}/bin/update-mime-database -V $out/share/mime > /dev/null
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fi
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if [ -w $out/share/applications ]; then
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${pkgs.buildPackages.desktop-file-utils}/bin/update-desktop-database $out/share/applications
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fi
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'';
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};
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}
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