lix/src/libstore/realisation.cc
regnat bab1cda0e6 Use the hash modulo in the derivation outputs
Rather than storing the derivation outputs as `drvPath!outputName` internally,
store them as `drvHashModulo!outputName` (or `outputHash!outputName` for
fixed-output derivations).

This makes the storage slightly more opaque, but enables an earlier
cutoff in cases where a fixed-output dependency changes (but keeps the
same output hash) − same as what we already do for input-addressed
derivations.
2020-12-11 21:17:23 +01:00

50 lines
1.3 KiB
C++

#include "realisation.hh"
#include "store-api.hh"
#include <nlohmann/json.hpp>
namespace nix {
MakeError(InvalidDerivationOutputId, Error);
DrvOutput DrvOutput::parse(const std::string &strRep) {
size_t n = strRep.find("!");
if (n == strRep.npos)
throw InvalidDerivationOutputId("Invalid derivation output id %s", strRep);
return DrvOutput{
.drvHash = Hash::parseAnyPrefixed(strRep.substr(0, n)),
.outputName = strRep.substr(n+1),
};
}
std::string DrvOutput::to_string() const {
return strHash() + "!" + outputName;
}
nlohmann::json Realisation::toJSON() const {
return nlohmann::json{
{"id", id.to_string()},
{"outPath", outPath.to_string()},
};
}
Realisation Realisation::fromJSON(
const nlohmann::json& json,
const std::string& whence) {
auto getField = [&](std::string fieldName) -> std::string {
auto fieldIterator = json.find(fieldName);
if (fieldIterator == json.end())
throw Error(
"Drv output info file '%1%' is corrupt, missing field %2%",
whence, fieldName);
return *fieldIterator;
};
return Realisation{
.id = DrvOutput::parse(getField("id")),
.outPath = StorePath(getField("outPath")),
};
}
} // namespace nix