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Make the Derived Path family of types inductive for dynamic derivations

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We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).

To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.

`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!

Important note: some JSON formats have changed.

We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This commit is contained in:
John Ericson 2023-01-15 17:39:04 -05:00
parent d00fe5f225
commit 60b7121d2c
48 changed files with 1136 additions and 267 deletions
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21
src/libstore/remote-store.cc
View file

@ -656,6 +656,9 @@ static void writeDerivedPaths(RemoteStore & store, RemoteStore::Connection & con
GET_PROTOCOL_MAJOR(conn.daemonVersion),
GET_PROTOCOL_MINOR(conn.daemonVersion));
},
[&](std::monostate) {
throw Error("wanted to build a derivation that is itself a build product, but the legacy 'ssh://' protocol doesn't support that. Try using 'ssh-ng://'");
},
}, sOrDrvPath);
}
conn.to << ss;
@ -670,9 +673,16 @@ void RemoteStore::copyDrvsFromEvalStore(
/* The remote doesn't have a way to access evalStore, so copy
the .drvs. */
RealisedPath::Set drvPaths2;
for (auto & i : paths)
if (auto p = std::get_if<DerivedPath::Built>(&i))
drvPaths2.insert(p->drvPath);
for (const auto & i : paths) {
std::visit(overloaded {
[&](const DerivedPath::Opaque & bp) {
// Do nothing, path is hopefully there already
},
[&](const DerivedPath::Built & bp) {
drvPaths2.insert(bp.drvPath->getBaseStorePath());
},
}, i.raw());
}
copyClosure(*evalStore, *this, drvPaths2);
}
}
@ -742,7 +752,8 @@ std::vector<KeyedBuildResult> RemoteStore::buildPathsWithResults(
};
OutputPathMap outputs;
auto drv = evalStore->readDerivation(bfd.drvPath);
auto drvPath = resolveDerivedPath(*evalStore, *bfd.drvPath);
auto drv = evalStore->readDerivation(drvPath);
const auto outputHashes = staticOutputHashes(*evalStore, drv); // FIXME: expensive
auto built = resolveDerivedPath(*this, bfd, &*evalStore);
for (auto & [output, outputPath] : built) {
@ -750,7 +761,7 @@ std::vector<KeyedBuildResult> RemoteStore::buildPathsWithResults(
if (!outputHash)
throw Error(
"the derivation '%s' doesn't have an output named '%s'",
printStorePath(bfd.drvPath), output);
printStorePath(drvPath), output);
auto outputId = DrvOutput{ *outputHash, output };
if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
auto realisation =