Update/adapt daemon CPU/IO priority options in `nix` module

Stop using `nice` related options like NixOS, and because `launchd`
recommends using `ProcessType` instead. Note this commit also changes
the default `ProcessType` for the `nix-daemon` from `Interactive` to
`Standard`.

2 files changed, 33 insertions, 15 deletions

diff --git a/modules/nix/default.nix b/modules/nix/default.nix
index edc8d4f..c816648 100644
--- a/modules/nix/default.nix
+++ b/modules/nix/default.nix
@@ -131,12 +131,26 @@ let
 in
 
 {
-  imports = [
-    (mkRemovedOptionModule [ "nix" "profile" ] "Use `nix.package` instead.")
-    (mkRemovedOptionModule [ "nix" "version" ] "Consider using `nix.package.version` instead.")
-    (mkRenamedOptionModule [ "users" "nix" "configureBuildUsers" ] [ "nix" "configureBuildUsers" ])
-    (mkRenamedOptionModule [ "users" "nix" "nrBuildUsers" ] [ "nix" "nrBuildUsers" ])
-  ] ++ mapAttrsToList (oldConf: newConf: mkRenamedOptionModule [ "nix" oldConf ] [ "nix" "settings" newConf ]) legacyConfMappings;
+  imports =
+    let
+      altOption = alt: "No `nix-darwin` equivilant to this NixOS option, consider using `${alt}` instead.";
+      consider = alt: "Consider using `${alt}` instead.";
+    in
+    [
+      # Only ever in NixOS
+      (mkRemovedOptionModule [ "nix" "enable" ] "No `nix-darwin` equivilant to this NixOS option.")
+      (mkRemovedOptionModule [ "nix" "daemonCPUSchedPolicy" ] (altOption "nix.daemonProcessType"))
+      (mkRemovedOptionModule [ "nix" "daemonIOSchedClass" ] (altOption "nix.daemonProcessType"))
+      (mkRemovedOptionModule [ "nix" "daemonIOSchedPriority" ] (altOption "nix.daemonIOLowPriority"))
+
+      # Option changes in `nix-darwin`
+      (mkRemovedOptionModule [ "nix" "profile" ] "Use `nix.package` instead.")
+      (mkRemovedOptionModule [ "nix" "version" ] (consider "nix.package.version"))
+      (mkRenamedOptionModule [ "users" "nix" "configureBuildUsers" ] [ "nix" "configureBuildUsers" ])
+      (mkRenamedOptionModule [ "users" "nix" "nrBuildUsers" ] [ "nix" "nrBuildUsers" ])
+      (mkRenamedOptionModule [ "nix" "daemonIONice" ] [ "nix" "daemonIOLowPriority" ])
+      (mkRemovedOptionModule [ "nix" "daemonNiceLevel" ] (consider "nix.daemonProcessType"))
+    ] ++ mapAttrsToList (oldConf: newConf: mkRenamedOptionModule [ "nix" oldConf ] [ "nix" "settings" newConf ]) legacyConfMappings;
 
   ###### interface
 
@@ -177,17 +191,22 @@ in
       };
 
       # Not in NixOS module
-      daemonNiceLevel = mkOption {
-        type = types.int;
-        default = 0;
+      daemonProcessType = mkOption {
+        type = types.enum [ "Background" "Standard" "Adaptive" "Interactive" ];
+        default = "Standard";
         description = ''
-          Nix daemon process priority. This priority propagates to build processes.
-          0 is the default Unix process priority, 19 is the lowest.
+          Nix daemon process resource limits class. These limits propagate to
+          build processes. <literal>Standard</literal> is the default process type
+          and will apply light resource limits, throttling its CPU usage and I/O
+          bandwidth.
+
+          See <command>man launchd.plist</command> for explanation of other
+          process types.
         '';
       };
 
       # Not in NixOS module
-      daemonIONice = mkOption {
+      daemonIOLowPriority = mkOption {
         type = types.bool;
         default = false;
         description = ''
diff --git a/modules/services/nix-daemon.nix b/modules/services/nix-daemon.nix
index 735d92c..5e87e51 100644
--- a/modules/services/nix-daemon.nix
+++ b/modules/services/nix-daemon.nix
@@ -48,9 +48,8 @@ in
         "/bin/sh" "-c"
         "/bin/wait4path ${config.nix.package}/bin/nix-daemon &amp;&amp; exec ${config.nix.package}/bin/nix-daemon"
       ];
-      serviceConfig.ProcessType = mkDefault "Interactive";
-      serviceConfig.LowPriorityIO = config.nix.daemonIONice;
-      serviceConfig.Nice = config.nix.daemonNiceLevel;
+      serviceConfig.ProcessType = config.nix.daemonProcessType;
+      serviceConfig.LowPriorityIO = config.nix.daemonIOLowPriority;
       serviceConfig.Label = "org.nixos.nix-daemon"; # must match daemon installed by Nix regardless of the launchd label Prefix
       serviceConfig.SoftResourceLimits.NumberOfFiles = mkDefault 4096;
       serviceConfig.StandardErrorPath = cfg.logFile;