lix/src/libexpr/flake/eval-cache.cc

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#include "eval-cache.hh"
#include "sqlite.hh"
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#include "eval.hh"
#include <set>
namespace nix::flake {
static const char * schema = R"sql(
create table if not exists Fingerprints (
fingerprint blob primary key not null,
timestamp integer not null
);
create table if not exists Attributes (
fingerprint blob not null,
attrPath text not null,
type integer,
value text,
primary key (fingerprint, attrPath),
foreign key (fingerprint) references Fingerprints(fingerprint) on delete cascade
);
)sql";
struct EvalCache::State
{
SQLite db;
SQLiteStmt insertFingerprint;
SQLiteStmt insertAttribute;
SQLiteStmt queryAttribute;
std::set<Fingerprint> fingerprints;
};
EvalCache::EvalCache()
: _state(std::make_unique<Sync<State>>())
{
auto state(_state->lock());
Path dbPath = getCacheDir() + "/nix/eval-cache-v1.sqlite";
createDirs(dirOf(dbPath));
state->db = SQLite(dbPath);
state->db.isCache();
state->db.exec(schema);
state->insertFingerprint.create(state->db,
"insert or ignore into Fingerprints(fingerprint, timestamp) values (?, ?)");
state->insertAttribute.create(state->db,
"insert or replace into Attributes(fingerprint, attrPath, type, value) values (?, ?, ?, ?)");
state->queryAttribute.create(state->db,
"select type, value from Attributes where fingerprint = ? and attrPath = ?");
}
enum ValueType {
Derivation = 1,
};
void EvalCache::addDerivation(
const Fingerprint & fingerprint,
const std::string & attrPath,
const Derivation & drv)
{
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if (!evalSettings.pureEval) return;
auto state(_state->lock());
if (state->fingerprints.insert(fingerprint).second)
// FIXME: update timestamp
state->insertFingerprint.use()
(fingerprint.hash, fingerprint.hashSize)
(time(0)).exec();
state->insertAttribute.use()
(fingerprint.hash, fingerprint.hashSize)
(attrPath)
(ValueType::Derivation)
(drv.drvPath + " " + drv.outPath + " " + drv.outputName).exec();
}
std::optional<EvalCache::Derivation> EvalCache::getDerivation(
const Fingerprint & fingerprint,
const std::string & attrPath)
{
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if (!evalSettings.pureEval) return {};
auto state(_state->lock());
auto queryAttribute(state->queryAttribute.use()
(fingerprint.hash, fingerprint.hashSize)
(attrPath));
if (!queryAttribute.next()) return {};
// FIXME: handle negative results
auto type = (ValueType) queryAttribute.getInt(0);
auto s = queryAttribute.getStr(1);
if (type != ValueType::Derivation) return {};
auto ss = tokenizeString<std::vector<std::string>>(s, " ");
debug("evaluation cache hit for '%s'", attrPath);
return Derivation { ss[0], ss[1], ss[2] };
}
EvalCache & EvalCache::singleton()
{
static std::unique_ptr<EvalCache> evalCache(new EvalCache());
return *evalCache;
}
}