nixpkgs/lib/customisation.nix
pennae dc895fb281 lib: make extendDerivation lighter on eval
the fix to extendDerivation in  unwittingly worsened eval performance by
quite a bit. set elements alone needed over 1GB extra after the change, which
seems disproportionate to how small it was. if we flip the logic used to
determine which outputs to install around and keep a "this one exactly" flag in
the specific outputs instead of a "all of them" in the root we can avoid most
of that cost.
2021-10-15 16:39:10 +02:00

249 lines
9.4 KiB
Nix

{ lib }:
rec {
/* `overrideDerivation drv f' takes a derivation (i.e., the result
of a call to the builtin function `derivation') and returns a new
derivation in which the attributes of the original are overridden
according to the function `f'. The function `f' is called with
the original derivation attributes.
`overrideDerivation' allows certain "ad-hoc" customisation
scenarios (e.g. in ~/.config/nixpkgs/config.nix). For instance,
if you want to "patch" the derivation returned by a package
function in Nixpkgs to build another version than what the
function itself provides, you can do something like this:
mySed = overrideDerivation pkgs.gnused (oldAttrs: {
name = "sed-4.2.2-pre";
src = fetchurl {
url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2;
sha256 = "11nq06d131y4wmf3drm0yk502d2xc6n5qy82cg88rb9nqd2lj41k";
};
patches = [];
});
For another application, see build-support/vm, where this
function is used to build arbitrary derivations inside a QEMU
virtual machine.
*/
overrideDerivation = drv: f:
let
newDrv = derivation (drv.drvAttrs // (f drv));
in lib.flip (extendDerivation true) newDrv (
{ meta = drv.meta or {};
passthru = if drv ? passthru then drv.passthru else {};
}
//
(drv.passthru or {})
//
(if (drv ? crossDrv && drv ? nativeDrv)
then {
crossDrv = overrideDerivation drv.crossDrv f;
nativeDrv = overrideDerivation drv.nativeDrv f;
}
else { }));
/* `makeOverridable` takes a function from attribute set to attribute set and
injects `override` attribute which can be used to override arguments of
the function.
nix-repl> x = {a, b}: { result = a + b; }
nix-repl> y = lib.makeOverridable x { a = 1; b = 2; }
nix-repl> y
{ override = «lambda»; overrideDerivation = «lambda»; result = 3; }
nix-repl> y.override { a = 10; }
{ override = «lambda»; overrideDerivation = «lambda»; result = 12; }
Please refer to "Nixpkgs Contributors Guide" section
"<pkg>.overrideDerivation" to learn about `overrideDerivation` and caveats
related to its use.
*/
makeOverridable = f: origArgs:
let
result = f origArgs;
# Creates a functor with the same arguments as f
copyArgs = g: lib.setFunctionArgs g (lib.functionArgs f);
# Changes the original arguments with (potentially a function that returns) a set of new attributes
overrideWith = newArgs: origArgs // (if lib.isFunction newArgs then newArgs origArgs else newArgs);
# Re-call the function but with different arguments
overrideArgs = copyArgs (newArgs: makeOverridable f (overrideWith newArgs));
# Change the result of the function call by applying g to it
overrideResult = g: makeOverridable (copyArgs (args: g (f args))) origArgs;
in
if builtins.isAttrs result then
result // {
override = overrideArgs;
overrideDerivation = fdrv: overrideResult (x: overrideDerivation x fdrv);
${if result ? overrideAttrs then "overrideAttrs" else null} = fdrv:
overrideResult (x: x.overrideAttrs fdrv);
}
else if lib.isFunction result then
# Transform the result into a functor while propagating its arguments
lib.setFunctionArgs result (lib.functionArgs result) // {
override = overrideArgs;
}
else result;
/* Call the package function in the file `fn' with the required
arguments automatically. The function is called with the
arguments `args', but any missing arguments are obtained from
`autoArgs'. This function is intended to be partially
parameterised, e.g.,
callPackage = callPackageWith pkgs;
pkgs = {
libfoo = callPackage ./foo.nix { };
libbar = callPackage ./bar.nix { };
};
If the `libbar' function expects an argument named `libfoo', it is
automatically passed as an argument. Overrides or missing
arguments can be supplied in `args', e.g.
libbar = callPackage ./bar.nix {
libfoo = null;
enableX11 = true;
};
*/
callPackageWith = autoArgs: fn: args:
let
f = if lib.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (lib.functionArgs f) autoArgs;
in makeOverridable f (auto // args);
/* Like callPackage, but for a function that returns an attribute
set of derivations. The override function is added to the
individual attributes. */
callPackagesWith = autoArgs: fn: args:
let
f = if lib.isFunction fn then fn else import fn;
auto = builtins.intersectAttrs (lib.functionArgs f) autoArgs;
origArgs = auto // args;
pkgs = f origArgs;
mkAttrOverridable = name: _: makeOverridable (newArgs: (f newArgs).${name}) origArgs;
in
if lib.isDerivation pkgs then throw
("function `callPackages` was called on a *single* derivation "
+ ''"${pkgs.name or "<unknown-name>"}";''
+ " did you mean to use `callPackage` instead?")
else lib.mapAttrs mkAttrOverridable pkgs;
/* Add attributes to each output of a derivation without changing
the derivation itself and check a given condition when evaluating. */
extendDerivation = condition: passthru: drv:
let
outputs = drv.outputs or [ "out" ];
commonAttrs = drv // (builtins.listToAttrs outputsList) //
({ all = map (x: x.value) outputsList; }) // passthru;
outputToAttrListElement = outputName:
{ name = outputName;
value = commonAttrs // {
inherit (drv.${outputName}) type outputName;
outputSpecified = true;
drvPath = assert condition; drv.${outputName}.drvPath;
outPath = assert condition; drv.${outputName}.outPath;
};
};
outputsList = map outputToAttrListElement outputs;
in commonAttrs // {
drvPath = assert condition; drv.drvPath;
outPath = assert condition; drv.outPath;
};
/* Strip a derivation of all non-essential attributes, returning
only those needed by hydra-eval-jobs. Also strictly evaluate the
result to ensure that there are no thunks kept alive to prevent
garbage collection. */
hydraJob = drv:
let
outputs = drv.outputs or ["out"];
commonAttrs =
{ inherit (drv) name system meta; inherit outputs; }
// lib.optionalAttrs (drv._hydraAggregate or false) {
_hydraAggregate = true;
constituents = map hydraJob (lib.flatten drv.constituents);
}
// (lib.listToAttrs outputsList);
makeOutput = outputName:
let output = drv.${outputName}; in
{ name = outputName;
value = commonAttrs // {
outPath = output.outPath;
drvPath = output.drvPath;
type = "derivation";
inherit outputName;
};
};
outputsList = map makeOutput outputs;
drv' = (lib.head outputsList).value;
in lib.deepSeq drv' drv';
/* Make a set of packages with a common scope. All packages called
with the provided `callPackage' will be evaluated with the same
arguments. Any package in the set may depend on any other. The
`overrideScope'` function allows subsequent modification of the package
set in a consistent way, i.e. all packages in the set will be
called with the overridden packages. The package sets may be
hierarchical: the packages in the set are called with the scope
provided by `newScope' and the set provides a `newScope' attribute
which can form the parent scope for later package sets. */
makeScope = newScope: f:
let self = f self // {
newScope = scope: newScope (self // scope);
callPackage = self.newScope {};
overrideScope = g: lib.warn
"`overrideScope` (from `lib.makeScope`) is deprecated. Do `overrideScope' (self: super: { })` instead of `overrideScope (super: self: { })`. All other overrides have the parameters in that order, including other definitions of `overrideScope`. This was the only definition violating the pattern."
(makeScope newScope (lib.fixedPoints.extends (lib.flip g) f));
overrideScope' = g: makeScope newScope (lib.fixedPoints.extends g f);
packages = f;
};
in self;
/* Like the above, but aims to support cross compilation. It's still ugly, but
hopefully it helps a little bit. */
makeScopeWithSplicing = splicePackages: newScope: otherSplices: keep: extra: f:
let
spliced0 = splicePackages {
pkgsBuildBuild = otherSplices.selfBuildBuild;
pkgsBuildHost = otherSplices.selfBuildHost;
pkgsBuildTarget = otherSplices.selfBuildTarget;
pkgsHostHost = otherSplices.selfHostHost;
pkgsHostTarget = self; # Not `otherSplices.selfHostTarget`;
pkgsTargetTarget = otherSplices.selfTargetTarget;
};
spliced = extra spliced0 // spliced0 // keep self;
self = f self // {
newScope = scope: newScope (spliced // scope);
callPackage = newScope spliced; # == self.newScope {};
# N.B. the other stages of the package set spliced in are *not*
# overridden.
overrideScope = g: makeScopeWithSplicing
splicePackages
newScope
otherSplices
keep
extra
(lib.fixedPoints.extends g f);
packages = f;
};
in self;
}