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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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76
src/libcmd/built-path.cc
View file

@ -8,13 +8,39 @@
namespace nix {
nlohmann::json BuiltPath::Built::toJSON(ref<Store> store) const {
nlohmann::json res;
res["drvPath"] = store->printStorePath(drvPath);
for (const auto& [output, path] : outputs) {
res["outputs"][output] = store->printStorePath(path);
#define CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, COMPARATOR) \
bool MY_TYPE ::operator COMPARATOR (const MY_TYPE & other) const \
{ \
const MY_TYPE* me = this; \
auto fields1 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
me = &other; \
auto fields2 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
return fields1 COMPARATOR fields2; \
}
return res;
#define CMP(CHILD_TYPE, MY_TYPE, FIELD) \
CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, ==) \
CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, !=) \
CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, <)
#define FIELD_TYPE std::pair<std::string, StorePath>
CMP(SingleBuiltPath, SingleBuiltPathBuilt, output)
#undef FIELD_TYPE
#define FIELD_TYPE std::map<std::string, StorePath>
CMP(SingleBuiltPath, BuiltPathBuilt, outputs)
#undef FIELD_TYPE
#undef CMP
#undef CMP_ONE
StorePath SingleBuiltPath::outPath() const
{
return std::visit(
overloaded{
[](const SingleBuiltPath::Opaque & p) { return p.path; },
[](const SingleBuiltPath::Built & b) { return b.output.second; },
}, raw()
);
}
StorePathSet BuiltPath::outPaths() const
@ -32,6 +58,40 @@ StorePathSet BuiltPath::outPaths() const
);
}
nlohmann::json BuiltPath::Built::toJSON(const Store & store) const
{
nlohmann::json res;
res["drvPath"] = drvPath->toJSON(store);
for (const auto & [outputName, outputPath] : outputs) {
res["outputs"][outputName] = store.printStorePath(outputPath);
}
return res;
}
nlohmann::json SingleBuiltPath::Built::toJSON(const Store & store) const
{
nlohmann::json res;
res["drvPath"] = drvPath->toJSON(store);
auto & [outputName, outputPath] = output;
res["output"] = outputName;
res["outputPath"] = store.printStorePath(outputPath);
return res;
}
nlohmann::json SingleBuiltPath::toJSON(const Store & store) const
{
return std::visit([&](const auto & buildable) {
return buildable.toJSON(store);
}, raw());
}
nlohmann::json BuiltPath::toJSON(const Store & store) const
{
return std::visit([&](const auto & buildable) {
return buildable.toJSON(store);
}, raw());
}
RealisedPath::Set BuiltPath::toRealisedPaths(Store & store) const
{
RealisedPath::Set res;
@ -40,7 +100,7 @@ RealisedPath::Set BuiltPath::toRealisedPaths(Store & store) const
[&](const BuiltPath::Opaque & p) { res.insert(p.path); },
[&](const BuiltPath::Built & p) {
auto drvHashes =
staticOutputHashes(store, store.readDerivation(p.drvPath));
staticOutputHashes(store, store.readDerivation(p.drvPath->outPath()));
for (auto& [outputName, outputPath] : p.outputs) {
if (experimentalFeatureSettings.isEnabled(
Xp::CaDerivations)) {
@ -48,7 +108,7 @@ RealisedPath::Set BuiltPath::toRealisedPaths(Store & store) const
if (!drvOutput)
throw Error(
"the derivation '%s' has unrealised output '%s' (derived-path.cc/toRealisedPaths)",
store.printStorePath(p.drvPath), outputName);
store.printStorePath(p.drvPath->outPath()), outputName);
auto thisRealisation = store.queryRealisation(
DrvOutput{*drvOutput, outputName});
assert(thisRealisation); // We’ve built it, so we must