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Merge pull request #6268 from thufschmitt/remove-the-variant-in-hashmodulo

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Simplify the handling of the hash modulo
This commit is contained in:
Eelco Dolstra 2022-03-29 20:26:47 +02:00 committed by GitHub
parent 2d572a250f 390269ed87
commit 03be091e0a
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 56 additions and 118 deletions
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38
src/libexpr/primops.cc
View file

@ -1222,34 +1222,26 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
DerivationOutput::Deferred { });
}
// Regular, non-CA derivation should always return a single hash and not
// hash per output.
auto hashModulo = hashDerivationModulo(*state.store, drv, true);
std::visit(overloaded {
[&](const DrvHash & drvHash) {
auto & h = drvHash.hash;
switch (drvHash.kind) {
case DrvHash::Kind::Deferred:
/* Outputs already deferred, nothing to do */
break;
auto hashModulo = hashDerivationModulo(*state.store, Derivation(drv), true);
switch (hashModulo.kind) {
case DrvHash::Kind::Regular:
for (auto & [outputName, output] : drv.outputs) {
auto outPath = state.store->makeOutputPath(outputName, h, drvName);
drv.env[outputName] = state.store->printStorePath(outPath);
output = DerivationOutput::InputAddressed {
for (auto & i : outputs) {
auto h = hashModulo.hashes.at(i);
auto outPath = state.store->makeOutputPath(i, h, drvName);
drv.env[i] = state.store->printStorePath(outPath);
drv.outputs.insert_or_assign(
i,
DerivationOutputInputAddressed {
.path = std::move(outPath),
};
});
}
break;
;
case DrvHash::Kind::Deferred:
for (auto & i : outputs) {
drv.outputs.insert_or_assign(i, DerivationOutputDeferred {});
}
}
},
[&](const CaOutputHashes &) {
// Shouldn't happen as the toplevel derivation is not CA.
assert(false);
},
},
hashModulo.raw());
}
/* Write the resulting term into the Nix store directory. */

75
src/libstore/derivations.cc
View file

@ -474,7 +474,7 @@ Sync<DrvHashes> drvHashes;
/* Look up the derivation by value and memoize the
`hashDerivationModulo` call.
*/
static const DrvHashModulo pathDerivationModulo(Store & store, const StorePath & drvPath)
static const DrvHash pathDerivationModulo(Store & store, const StorePath & drvPath)
{
{
auto hashes = drvHashes.lock();
@ -509,7 +509,7 @@ static const DrvHashModulo pathDerivationModulo(Store & store, const StorePath &
don't leak the provenance of fixed outputs, reducing pointless cache
misses as the build itself won't know this.
*/
DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs)
DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs)
{
auto type = drv.type();
@ -524,7 +524,10 @@ DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool m
+ store.printStorePath(dof.path(store, drv.name, i.first)));
outputHashes.insert_or_assign(i.first, std::move(hash));
}
return outputHashes;
return DrvHash{
.hashes = outputHashes,
.kind = DrvHash::Kind::Regular,
};
}
auto kind = std::visit(overloaded {
@ -540,65 +543,36 @@ DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool m
},
}, drv.type().raw());
/* For other derivations, replace the inputs paths with recursive
calls to this function. */
std::map<std::string, StringSet> inputs2;
for (auto & [drvPath, inputOutputs0] : drv.inputDrvs) {
// Avoid lambda capture restriction with standard / Clang
auto & inputOutputs = inputOutputs0;
const auto & res = pathDerivationModulo(store, drvPath);
std::visit(overloaded {
// Regular non-CA derivation, replace derivation
[&](const DrvHash & drvHash) {
kind |= drvHash.kind;
inputs2.insert_or_assign(drvHash.hash.to_string(Base16, false), inputOutputs);
},
// CA derivation's output hashes
[&](const CaOutputHashes & outputHashes) {
std::set<std::string> justOut = { "out" };
for (auto & output : inputOutputs) {
/* Put each one in with a single "out" output.. */
const auto h = outputHashes.at(output);
inputs2.insert_or_assign(
h.to_string(Base16, false),
justOut);
if (res.kind == DrvHash::Kind::Deferred)
kind = DrvHash::Kind::Deferred;
for (auto & outputName : inputOutputs) {
const auto h = res.hashes.at(outputName);
inputs2[h.to_string(Base16, false)].insert(outputName);
}
},
}, res.raw());
}
auto hash = hashString(htSHA256, drv.unparse(store, maskOutputs, &inputs2));
return DrvHash { .hash = hash, .kind = kind };
}
void operator |= (DrvHash::Kind & self, const DrvHash::Kind & other) noexcept
{
switch (other) {
case DrvHash::Kind::Regular:
break;
case DrvHash::Kind::Deferred:
self = other;
break;
std::map<std::string, Hash> outputHashes;
for (const auto & [outputName, _] : drv.outputs) {
outputHashes.insert_or_assign(outputName, hash);
}
return DrvHash {
.hashes = outputHashes,
.kind = kind,
};
}
std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation & drv)
{
std::map<std::string, Hash> res;
std::visit(overloaded {
[&](const DrvHash & drvHash) {
for (auto & outputName : drv.outputNames()) {
res.insert({outputName, drvHash.hash});
}
},
[&](const CaOutputHashes & outputHashes) {
res = outputHashes;
},
}, hashDerivationModulo(store, drv, true).raw());
return res;
return hashDerivationModulo(store, drv, true).hashes;
}
@ -747,7 +721,7 @@ static void rewriteDerivation(Store & store, BasicDerivation & drv, const String
auto hashModulo = hashDerivationModulo(store, Derivation(drv), true);
for (auto & [outputName, output] : drv.outputs) {
if (std::holds_alternative<DerivationOutput::Deferred>(output.raw())) {
auto & h = hashModulo.requireNoFixedNonDeferred();
auto & h = hashModulo.hashes.at(outputName);
auto outPath = store.makeOutputPath(outputName, h, drv.name);
drv.env[outputName] = store.printStorePath(outPath);
output = DerivationOutput::InputAddressed {
@ -758,13 +732,6 @@ static void rewriteDerivation(Store & store, BasicDerivation & drv, const String
}
const Hash & DrvHashModulo::requireNoFixedNonDeferred() const {
auto * drvHashOpt = std::get_if<DrvHash>(&raw());
assert(drvHashOpt);
assert(drvHashOpt->kind == DrvHash::Kind::Regular);
return drvHashOpt->hash;
}
static bool tryResolveInput(
Store & store, StorePathSet & inputSrcs, StringMap & inputRewrites,
const StorePath & inputDrv, const StringSet & inputOutputs)

36
src/libstore/derivations.hh
View file

@ -202,12 +202,14 @@ bool isDerivation(const std::string & fileName);
the output name is "out". */
std::string outputPathName(std::string_view drvName, std::string_view outputName);
// known CA drv's output hashes, current just for fixed-output derivations
// whose output hashes are always known since they are fixed up-front.
typedef std::map<std::string, Hash> CaOutputHashes;
// The hashes modulo of a derivation.
//
// Each output is given a hash, although in practice only the content-addressed
// derivations (fixed-output or not) will have a different hash for each
// output.
struct DrvHash {
Hash hash;
std::map<std::string, Hash> hashes;
enum struct Kind: bool {
// Statically determined derivations.
@ -222,28 +224,6 @@ struct DrvHash {
void operator |= (DrvHash::Kind & self, const DrvHash::Kind & other) noexcept;
typedef std::variant<
// Regular normalized derivation hash, and whether it was deferred (because
// an ancestor derivation is a floating content addressed derivation).
DrvHash,
// Fixed-output derivation hashes
CaOutputHashes
> _DrvHashModuloRaw;
struct DrvHashModulo : _DrvHashModuloRaw {
using Raw = _DrvHashModuloRaw;
using Raw::Raw;
/* Get hash, throwing if it is per-output CA hashes or a
deferred Drv hash.
*/
const Hash & requireNoFixedNonDeferred() const;
inline const Raw & raw() const {
return static_cast<const Raw &>(*this);
}
};
/* Returns hashes with the details of fixed-output subderivations
expunged.
@ -267,7 +247,7 @@ struct DrvHashModulo : _DrvHashModuloRaw {
ATerm, after subderivations have been likewise expunged from that
derivation.
*/
DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs);
/*
Return a map associating each output to a hash that uniquely identifies its
@ -276,7 +256,7 @@ DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool m
std::map<std::string, Hash> staticOutputHashes(Store& store, const Derivation& drv);
/* Memoisation of hashDerivationModulo(). */
typedef std::map<StorePath, DrvHashModulo> DrvHashes;
typedef std::map<StorePath, DrvHash> DrvHashes;
// FIXME: global, though at least thread-safe.
extern Sync<DrvHashes> drvHashes;

9
src/libstore/local-store.cc
View file

@ -695,16 +695,15 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
// combinations that are currently prohibited.
drv.type();
std::optional<Hash> h;
std::optional<DrvHash> hashesModulo;
for (auto & i : drv.outputs) {
std::visit(overloaded {
[&](const DerivationOutput::InputAddressed & doia) {
if (!h) {
if (!hashesModulo) {
// somewhat expensive so we do lazily
auto h0 = hashDerivationModulo(*this, drv, true);
h = h0.requireNoFixedNonDeferred();
hashesModulo = hashDerivationModulo(*this, drv, true);
}
StorePath recomputed = makeOutputPath(i.first, *h, drvName);
StorePath recomputed = makeOutputPath(i.first, hashesModulo->hashes.at(i.first), drvName);
if (doia.path != recomputed)
throw Error("derivation '%s' has incorrect output '%s', should be '%s'",
printStorePath(drvPath), printStorePath(doia.path), printStorePath(recomputed));

4
src/nix/develop.cc
View file

@ -204,10 +204,10 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore
output.second = DerivationOutput::Deferred { };
drv.env[output.first] = "";
}
auto h0 = hashDerivationModulo(*evalStore, drv, true);
const Hash & h = h0.requireNoFixedNonDeferred();
auto hashesModulo = hashDerivationModulo(*evalStore, drv, true);
for (auto & output : drv.outputs) {
Hash h = hashesModulo.hashes.at(output.first);
auto outPath = store->makeOutputPath(output.first, h, drv.name);
output.second = DerivationOutput::InputAddressed {
.path = outPath,