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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
Download patch file Download diff file Expand all files Collapse all files

2
src/libexpr/eval-cache.cc
View file

@ -599,7 +599,7 @@ string_t AttrCursor::getStringWithContext()
return d.drvPath;
},
[&](const NixStringContextElem::Built & b) -> const StorePath & {
return b.drvPath;
return b.drvPath->getBaseStorePath();
},
[&](const NixStringContextElem::Opaque & o) -> const StorePath & {
return o.path;

59
src/libexpr/eval.cc
View file

@ -1042,7 +1042,7 @@ void EvalState::mkOutputString(
: DownstreamPlaceholder::unknownCaOutput(drvPath, outputName, xpSettings).render(),
NixStringContext {
NixStringContextElem::Built {
.drvPath = drvPath,
.drvPath = makeConstantStorePathRef(drvPath),
.output = outputName,
}
});
@ -2299,7 +2299,7 @@ StorePath EvalState::coerceToStorePath(const PosIdx pos, Value & v, NixStringCon
}
std::pair<DerivedPath, std::string_view> EvalState::coerceToDerivedPathUnchecked(const PosIdx pos, Value & v, std::string_view errorCtx)
std::pair<SingleDerivedPath, std::string_view> EvalState::coerceToSingleDerivedPathUnchecked(const PosIdx pos, Value & v, std::string_view errorCtx)
{
NixStringContext context;
auto s = forceString(v, context, pos, errorCtx);
@ -2310,21 +2310,16 @@ std::pair<DerivedPath, std::string_view> EvalState::coerceToDerivedPathUnchecked
s, csize)
.withTrace(pos, errorCtx).debugThrow<EvalError>();
auto derivedPath = std::visit(overloaded {
[&](NixStringContextElem::Opaque && o) -> DerivedPath {
return DerivedPath::Opaque {
.path = std::move(o.path),
};
[&](NixStringContextElem::Opaque && o) -> SingleDerivedPath {
return std::move(o);
},
[&](NixStringContextElem::DrvDeep &&) -> DerivedPath {
[&](NixStringContextElem::DrvDeep &&) -> SingleDerivedPath {
error(
"string '%s' has a context which refers to a complete source and binary closure. This is not supported at this time",
s).withTrace(pos, errorCtx).debugThrow<EvalError>();
},
[&](NixStringContextElem::Built && b) -> DerivedPath {
return DerivedPath::Built {
.drvPath = std::move(b.drvPath),
.outputs = OutputsSpec::Names { std::move(b.output) },
};
[&](NixStringContextElem::Built && b) -> SingleDerivedPath {
return std::move(b);
},
}, ((NixStringContextElem &&) *context.begin()).raw());
return {
@ -2334,12 +2329,12 @@ std::pair<DerivedPath, std::string_view> EvalState::coerceToDerivedPathUnchecked
}
DerivedPath EvalState::coerceToDerivedPath(const PosIdx pos, Value & v, std::string_view errorCtx)
SingleDerivedPath EvalState::coerceToSingleDerivedPath(const PosIdx pos, Value & v, std::string_view errorCtx)
{
auto [derivedPath, s_] = coerceToDerivedPathUnchecked(pos, v, errorCtx);
auto [derivedPath, s_] = coerceToSingleDerivedPathUnchecked(pos, v, errorCtx);
auto s = s_;
std::visit(overloaded {
[&](const DerivedPath::Opaque & o) {
[&](const SingleDerivedPath::Opaque & o) {
auto sExpected = store->printStorePath(o.path);
if (s != sExpected)
error(
@ -2347,25 +2342,27 @@ DerivedPath EvalState::coerceToDerivedPath(const PosIdx pos, Value & v, std::str
s, sExpected)
.withTrace(pos, errorCtx).debugThrow<EvalError>();
},
[&](const DerivedPath::Built & b) {
// TODO need derived path with single output to make this
// total. Will add as part of RFC 92 work and then this is
// cleaned up.
auto output = *std::get<OutputsSpec::Names>(b.outputs).begin();
auto drv = store->readDerivation(b.drvPath);
auto i = drv.outputs.find(output);
if (i == drv.outputs.end())
throw Error("derivation '%s' does not have output '%s'", store->printStorePath(b.drvPath), output);
auto optOutputPath = i->second.path(*store, drv.name, output);
// This is testing for the case of CA derivations
auto sExpected = optOutputPath
? store->printStorePath(*optOutputPath)
: DownstreamPlaceholder::unknownCaOutput(b.drvPath, output).render();
[&](const SingleDerivedPath::Built & b) {
auto sExpected = std::visit(overloaded {
[&](const SingleDerivedPath::Opaque & o) {
auto drv = store->readDerivation(o.path);
auto i = drv.outputs.find(b.output);
if (i == drv.outputs.end())
throw Error("derivation '%s' does not have output '%s'", b.drvPath->to_string(*store), b.output);
auto optOutputPath = i->second.path(*store, drv.name, b.output);
// This is testing for the case of CA derivations
return optOutputPath
? store->printStorePath(*optOutputPath)
: DownstreamPlaceholder::fromSingleDerivedPathBuilt(b).render();
},
[&](const SingleDerivedPath::Built & o) {
return DownstreamPlaceholder::fromSingleDerivedPathBuilt(b).render();
},
}, b.drvPath->raw());
if (s != sExpected)
error(
"string '%s' has context with the output '%s' from derivation '%s', but the string is not the right placeholder for this derivation output. It should be '%s'",
s, output, store->printStorePath(b.drvPath), sExpected)
s, b.output, b.drvPath->to_string(*store), sExpected)
.withTrace(pos, errorCtx).debugThrow<EvalError>();
}
}, derivedPath.raw());

10
src/libexpr/eval.hh
View file

@ -22,7 +22,7 @@ namespace nix {
class Store;
class EvalState;
class StorePath;
struct DerivedPath;
struct SingleDerivedPath;
enum RepairFlag : bool;
@ -532,12 +532,12 @@ public:
StorePath coerceToStorePath(const PosIdx pos, Value & v, NixStringContext & context, std::string_view errorCtx);
/**
* Part of `coerceToDerivedPath()` without any store IO which is exposed for unit testing only.
* Part of `coerceToSingleDerivedPath()` without any store IO which is exposed for unit testing only.
*/
std::pair<DerivedPath, std::string_view> coerceToDerivedPathUnchecked(const PosIdx pos, Value & v, std::string_view errorCtx);
std::pair<SingleDerivedPath, std::string_view> coerceToSingleDerivedPathUnchecked(const PosIdx pos, Value & v, std::string_view errorCtx);
/**
* Coerce to `DerivedPath`.
* Coerce to `SingleDerivedPath`.
*
* Must be a string which is either a literal store path or a
* "placeholder (see `DownstreamPlaceholder`).
@ -551,7 +551,7 @@ public:
* source of truth, and ultimately tells us what we want, and then
* we ensure the string corresponds to it.
*/
DerivedPath coerceToDerivedPath(const PosIdx pos, Value & v, std::string_view errorCtx);
SingleDerivedPath coerceToSingleDerivedPath(const PosIdx pos, Value & v, std::string_view errorCtx);
public:

15
src/libexpr/primops.cc
View file

@ -56,7 +56,7 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
.drvPath = b.drvPath,
.outputs = OutputsSpec::Names { b.output },
});
ensureValid(b.drvPath);
ensureValid(b.drvPath->getBaseStorePath());
},
[&](const NixStringContextElem::Opaque & o) {
auto ctxS = store->printStorePath(o.path);
@ -77,7 +77,7 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
if (!evalSettings.enableImportFromDerivation)
debugThrowLastTrace(Error(
"cannot build '%1%' during evaluation because the option 'allow-import-from-derivation' is disabled",
store->printStorePath(drvs.begin()->drvPath)));
drvs.begin()->to_string(*store)));
/* Build/substitute the context. */
std::vector<DerivedPath> buildReqs;
@ -95,7 +95,11 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
/* Get all the output paths corresponding to the placeholders we had */
if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
res.insert_or_assign(
DownstreamPlaceholder::unknownCaOutput(drv.drvPath, outputName).render(),
DownstreamPlaceholder::fromSingleDerivedPathBuilt(
SingleDerivedPath::Built {
.drvPath = drv.drvPath,
.output = outputName,
}).render(),
store->printStorePath(outputPath)
);
}
@ -1251,7 +1255,10 @@ drvName, Bindings * attrs, Value & v)
}
},
[&](const NixStringContextElem::Built & b) {
drv.inputDrvs[b.drvPath].insert(b.output);
if (auto * p = std::get_if<DerivedPath::Opaque>(&*b.drvPath))
drv.inputDrvs[p->path].insert(b.output);
else
throw UnimplementedError("Dependencies on the outputs of dynamic derivations are not yet supported");
},
[&](const NixStringContextElem::Opaque & o) {
drv.inputSrcs.insert(o.path);

7
src/libexpr/primops/context.cc
View file

@ -106,7 +106,10 @@ static void prim_getContext(EvalState & state, const PosIdx pos, Value * * args,
contextInfos[std::move(d.drvPath)].allOutputs = true;
},
[&](NixStringContextElem::Built && b) {
contextInfos[std::move(b.drvPath)].outputs.emplace_back(std::move(b.output));
// FIXME should eventually show string context as is, no
// resolving here.
auto drvPath = resolveDerivedPath(*state.store, *b.drvPath);
contextInfos[std::move(drvPath)].outputs.emplace_back(std::move(b.output));
},
[&](NixStringContextElem::Opaque && o) {
contextInfos[std::move(o.path)].path = true;
@ -222,7 +225,7 @@ static void prim_appendContext(EvalState & state, const PosIdx pos, Value * * ar
for (auto elem : iter->value->listItems()) {
auto outputName = state.forceStringNoCtx(*elem, iter->pos, "while evaluating an output name within a string context");
context.emplace(NixStringContextElem::Built {
.drvPath = namePath,
.drvPath = makeConstantStorePathRef(namePath),
.output = std::string { outputName },
});
}

26
src/libexpr/tests/derived-path.cc
View file

@ -21,12 +21,12 @@ TEST_F(DerivedPathExpressionTest, force_init)
RC_GTEST_FIXTURE_PROP(
DerivedPathExpressionTest,
prop_opaque_path_round_trip,
(const DerivedPath::Opaque & o))
(const SingleDerivedPath::Opaque & o))
{
auto * v = state.allocValue();
state.mkStorePathString(o.path, *v);
auto d = state.coerceToDerivedPath(noPos, *v, "");
RC_ASSERT(DerivedPath { o } == d);
auto d = state.coerceToSingleDerivedPath(noPos, *v, "");
RC_ASSERT(SingleDerivedPath { o } == d);
}
// TODO use DerivedPath::Built for parameter once it supports a single output
@ -46,12 +46,12 @@ RC_GTEST_FIXTURE_PROP(
auto * v = state.allocValue();
state.mkOutputString(*v, drvPath, outputName.name, std::nullopt, mockXpSettings);
auto [d, _] = state.coerceToDerivedPathUnchecked(noPos, *v, "");
DerivedPath::Built b {
.drvPath = drvPath,
.outputs = OutputsSpec::Names { outputName.name },
auto [d, _] = state.coerceToSingleDerivedPathUnchecked(noPos, *v, "");
SingleDerivedPath::Built b {
.drvPath = makeConstantStorePathRef(drvPath),
.output = outputName.name,
};
RC_ASSERT(DerivedPath { b } == d);
RC_ASSERT(SingleDerivedPath { b } == d);
}
RC_GTEST_FIXTURE_PROP(
@ -61,12 +61,12 @@ RC_GTEST_FIXTURE_PROP(
{
auto * v = state.allocValue();
state.mkOutputString(*v, drvPath, outputName.name, outPath);
auto [d, _] = state.coerceToDerivedPathUnchecked(noPos, *v, "");
DerivedPath::Built b {
.drvPath = drvPath,
.outputs = OutputsSpec::Names { outputName.name },
auto [d, _] = state.coerceToSingleDerivedPathUnchecked(noPos, *v, "");
SingleDerivedPath::Built b {
.drvPath = makeConstantStorePathRef(drvPath),
.output = outputName.name,
};
RC_ASSERT(DerivedPath { b } == d);
RC_ASSERT(SingleDerivedPath { b } == d);
}
} /* namespace nix */

70
src/libexpr/tests/value/context.cc
View file

@ -8,6 +8,8 @@
namespace nix {
// Test a few cases of invalid string context elements.
TEST(NixStringContextElemTest, empty_invalid) {
EXPECT_THROW(
NixStringContextElem::parse(""),
@ -38,6 +40,10 @@ TEST(NixStringContextElemTest, slash_invalid) {
BadStorePath);
}
/**
* Round trip (string <-> data structure) test for
* `NixStringContextElem::Opaque`.
*/
TEST(NixStringContextElemTest, opaque) {
std::string_view opaque = "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x";
auto elem = NixStringContextElem::parse(opaque);
@ -47,6 +53,10 @@ TEST(NixStringContextElemTest, opaque) {
ASSERT_EQ(elem.to_string(), opaque);
}
/**
* Round trip (string <-> data structure) test for
* `NixStringContextElem::DrvDeep`.
*/
TEST(NixStringContextElemTest, drvDeep) {
std::string_view drvDeep = "=g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
auto elem = NixStringContextElem::parse(drvDeep);
@ -56,28 +66,62 @@ TEST(NixStringContextElemTest, drvDeep) {
ASSERT_EQ(elem.to_string(), drvDeep);
}
TEST(NixStringContextElemTest, built) {
/**
* Round trip (string <-> data structure) test for a simpler
* `NixStringContextElem::Built`.
*/
TEST(NixStringContextElemTest, built_opaque) {
std::string_view built = "!foo!g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
auto elem = NixStringContextElem::parse(built);
auto * p = std::get_if<NixStringContextElem::Built>(&elem);
ASSERT_TRUE(p);
ASSERT_EQ(p->output, "foo");
ASSERT_EQ(p->drvPath, StorePath { built.substr(5) });
ASSERT_EQ(*p->drvPath, ((SingleDerivedPath) SingleDerivedPath::Opaque {
.path = StorePath { built.substr(5) },
}));
ASSERT_EQ(elem.to_string(), built);
}
/**
* Round trip (string <-> data structure) test for a more complex,
* inductive `NixStringContextElem::Built`.
*/
TEST(NixStringContextElemTest, built_built) {
/**
* We set these in tests rather than the regular globals so we don't have
* to worry about race conditions if the tests run concurrently.
*/
ExperimentalFeatureSettings mockXpSettings;
mockXpSettings.set("experimental-features", "dynamic-derivations ca-derivations");
std::string_view built = "!foo!bar!g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv";
auto elem = NixStringContextElem::parse(built, mockXpSettings);
auto * p = std::get_if<NixStringContextElem::Built>(&elem);
ASSERT_TRUE(p);
ASSERT_EQ(p->output, "foo");
auto * drvPath = std::get_if<SingleDerivedPath::Built>(&*p->drvPath);
ASSERT_TRUE(drvPath);
ASSERT_EQ(drvPath->output, "bar");
ASSERT_EQ(*drvPath->drvPath, ((SingleDerivedPath) SingleDerivedPath::Opaque {
.path = StorePath { built.substr(9) },
}));
ASSERT_EQ(elem.to_string(), built);
}
/**
* Without the right experimental features enabled, we cannot parse a
* complex inductive string context element.
*/
TEST(NixStringContextElemTest, built_built_xp) {
ASSERT_THROW(
NixStringContextElem::parse("!foo!bar!g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-x.drv"), MissingExperimentalFeature);
}
}
namespace rc {
using namespace nix;
Gen<NixStringContextElem::Opaque> Arbitrary<NixStringContextElem::Opaque>::arbitrary()
{
return gen::just(NixStringContextElem::Opaque {
.path = *gen::arbitrary<StorePath>(),
});
}
Gen<NixStringContextElem::DrvDeep> Arbitrary<NixStringContextElem::DrvDeep>::arbitrary()
{
return gen::just(NixStringContextElem::DrvDeep {
@ -85,14 +129,6 @@ Gen<NixStringContextElem::DrvDeep> Arbitrary<NixStringContextElem::DrvDeep>::arb
});
}
Gen<NixStringContextElem::Built> Arbitrary<NixStringContextElem::Built>::arbitrary()
{
return gen::just(NixStringContextElem::Built {
.drvPath = *gen::arbitrary<StorePath>(),
.output = (*gen::arbitrary<StorePathName>()).name,
});
}
Gen<NixStringContextElem> Arbitrary<NixStringContextElem>::arbitrary()
{
switch (*gen::inRange<uint8_t>(0, std::variant_size_v<NixStringContextElem::Raw>)) {

97
src/libexpr/value/context.cc
View file

@ -4,29 +4,52 @@
namespace nix {
NixStringContextElem NixStringContextElem::parse(std::string_view s0)
NixStringContextElem NixStringContextElem::parse(
std::string_view s0,
const ExperimentalFeatureSettings & xpSettings)
{
std::string_view s = s0;
std::function<SingleDerivedPath()> parseRest;
parseRest = [&]() -> SingleDerivedPath {
// Case on whether there is a '!'
size_t index = s.find("!");
if (index == std::string_view::npos) {
return SingleDerivedPath::Opaque {
.path = StorePath { s },
};
} else {
std::string output { s.substr(0, index) };
// Advance string to parse after the '!'
s = s.substr(index + 1);
auto drv = make_ref<SingleDerivedPath>(parseRest());
drvRequireExperiment(*drv, xpSettings);
return SingleDerivedPath::Built {
.drvPath = std::move(drv),
.output = std::move(output),
};
}
};
if (s.size() == 0) {
throw BadNixStringContextElem(s0,
"String context element should never be an empty string");
}
switch (s.at(0)) {
case '!': {
s = s.substr(1); // advance string to parse after first !
size_t index = s.find("!");
// This makes index + 1 safe. Index can be the length (one after index
// of last character), so given any valid character index --- a
// successful find --- we can add one.
if (index == std::string_view::npos) {
// Advance string to parse after the '!'
s = s.substr(1);
// Find *second* '!'
if (s.find("!") == std::string_view::npos) {
throw BadNixStringContextElem(s0,
"String content element beginning with '!' should have a second '!'");
}
return NixStringContextElem::Built {
.drvPath = StorePath { s.substr(index + 1) },
.output = std::string(s.substr(0, index)),
};
return std::visit(
[&](auto x) -> NixStringContextElem { return std::move(x); },
parseRest());
}
case '=': {
return NixStringContextElem::DrvDeep {
@ -34,33 +57,51 @@ NixStringContextElem NixStringContextElem::parse(std::string_view s0)
};
}
default: {
return NixStringContextElem::Opaque {
.path = StorePath { s },
};
// Ensure no '!'
if (s.find("!") != std::string_view::npos) {
throw BadNixStringContextElem(s0,
"String content element not beginning with '!' should not have a second '!'");
}
return std::visit(
[&](auto x) -> NixStringContextElem { return std::move(x); },
parseRest());
}
}
}
std::string NixStringContextElem::to_string() const {
return std::visit(overloaded {
std::string NixStringContextElem::to_string() const
{
std::string res;
std::function<void(const SingleDerivedPath &)> toStringRest;
toStringRest = [&](auto & p) {
std::visit(overloaded {
[&](const SingleDerivedPath::Opaque & o) {
res += o.path.to_string();
},
[&](const SingleDerivedPath::Built & o) {
res += o.output;
res += '!';
toStringRest(*o.drvPath);
},
}, p.raw());
};
std::visit(overloaded {
[&](const NixStringContextElem::Built & b) {
std::string res;
res += '!';
res += b.output;
res += '!';
res += b.drvPath.to_string();
return res;
},
[&](const NixStringContextElem::DrvDeep & d) {
std::string res;
res += '=';
res += d.drvPath.to_string();
return res;
toStringRest(b);
},
[&](const NixStringContextElem::Opaque & o) {
return std::string { o.path.to_string() };
toStringRest(o);
},
[&](const NixStringContextElem::DrvDeep & d) {
res += '=';
res += d.drvPath.to_string();
},
}, raw());
return res;
}
}

21
src/libexpr/value/context.hh
View file

@ -3,7 +3,7 @@
#include "util.hh"
#include "comparator.hh"
#include "path.hh"
#include "derived-path.hh"
#include <variant>
@ -31,11 +31,7 @@ public:
*
* Encoded as just the path: ‘<path>’.
*/
struct NixStringContextElem_Opaque {
StorePath path;
GENERATE_CMP(NixStringContextElem_Opaque, me->path);
};
typedef SingleDerivedPath::Opaque NixStringContextElem_Opaque;
/**
* Path to a derivation and its entire build closure.
@ -57,12 +53,7 @@ struct NixStringContextElem_DrvDeep {
*
* Encoded in the form ‘!<output>!<drvPath>’.
*/
struct NixStringContextElem_Built {
StorePath drvPath;
std::string output;
GENERATE_CMP(NixStringContextElem_Built, me->drvPath, me->output);
};
typedef SingleDerivedPath::Built NixStringContextElem_Built;
using _NixStringContextElem_Raw = std::variant<
NixStringContextElem_Opaque,
@ -93,8 +84,12 @@ struct NixStringContextElem : _NixStringContextElem_Raw {
* - ‘<path>’
* - ‘=<path>’
* - ‘!<name>!<path>’
*
* @param xpSettings Stop-gap to avoid globals during unit tests.
*/
static NixStringContextElem parse(std::string_view s);
static NixStringContextElem parse(
std::string_view s,
const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);
std::string to_string() const;
};