Rework the db schema for derivation outputs

Add a new table for tracking the derivation output mappings.

We used to hijack the `DerivationOutputs` table for that, but (despite its
name), it isn't a really good fit:

- Its entries depend on the drv being a valid path, making it play badly with
  garbage collection and preventing us to copy a drv output without copying
  the whole drv closure too;
- It dosen't guaranty that the output path exists;

By using a different table, we can experiment with a different schema better
suited for tracking the output mappings of CA derivations.
(incidentally, this also fixes #4138)
This commit is contained in:
regnat 2020-10-20 15:14:02 +02:00
parent 58cdab64ac
commit 3ac9d74eb1
5 changed files with 172 additions and 80 deletions

View file

@ -493,8 +493,9 @@ void DerivationGoal::inputsRealised()
if (useDerivation) {
auto & fullDrv = *dynamic_cast<Derivation *>(drv.get());
if ((!fullDrv.inputDrvs.empty() && derivationIsCA(fullDrv.type()))
|| fullDrv.type() == DerivationType::DeferredInputAddressed) {
if (settings.isExperimentalFeatureEnabled("ca-derivations") &&
((!fullDrv.inputDrvs.empty() && derivationIsCA(fullDrv.type()))
|| fullDrv.type() == DerivationType::DeferredInputAddressed)) {
/* We are be able to resolve this derivation based on the
now-known results of dependencies. If so, we become a stub goal
aliasing that resolved derivation goal */
@ -3405,12 +3406,11 @@ void DerivationGoal::registerOutputs()
drvPathResolved = writeDerivation(worker.store, drv2);
}
if (useDerivation || isCaFloating)
if (settings.isExperimentalFeatureEnabled("ca-derivations"))
for (auto& [outputName, newInfo] : infos)
worker.store.registerDrvOutput(
DrvOutputId{drvPathResolved, outputName},
DrvOutputInfo{.outPath = newInfo.path,
.resolvedDrv = drvPathResolved});
worker.store.registerDrvOutput(Realisation{
.id = DrvOutput{drvPathResolved, outputName},
.outPath = newInfo.path});
}

View file

@ -0,0 +1,11 @@
-- Extension of the sql schema for content-addressed derivations.
-- Won't be loaded unless the experimental feature `ca-derivations`
-- is enabled
create table if not exists Realisations (
drvPath text not null,
outputName text not null, -- symbolic output id, usually "out"
outputPath integer not null,
primary key (drvPath, outputName),
foreign key (outputPath) references ValidPaths(id) on delete cascade
);

View file

@ -52,12 +52,52 @@ struct LocalStore::State::Stmts {
SQLiteStmt QueryReferrers;
SQLiteStmt InvalidatePath;
SQLiteStmt AddDerivationOutput;
SQLiteStmt RegisterRealisedOutput;
SQLiteStmt QueryValidDerivers;
SQLiteStmt QueryDerivationOutputs;
SQLiteStmt QueryRealisedOutput;
SQLiteStmt QueryAllRealisedOutputs;
SQLiteStmt QueryPathFromHashPart;
SQLiteStmt QueryValidPaths;
};
int getSchema(Path schemaPath)
{
int curSchema = 0;
if (pathExists(schemaPath)) {
string s = readFile(schemaPath);
if (!string2Int(s, curSchema))
throw Error("'%1%' is corrupt", schemaPath);
}
return curSchema;
}
void migrateCASchema(SQLite& db, Path schemaPath, AutoCloseFD& lockFd)
{
const int nixCASchemaVersion = 1;
int curCASchema = getSchema(schemaPath);
if (curCASchema != nixCASchemaVersion) {
if (curCASchema > nixCASchemaVersion) {
throw Error("current Nix store ca-schema is version %1%, but I only support %2%",
curCASchema, nixCASchemaVersion);
}
if (!lockFile(lockFd.get(), ltWrite, false)) {
printInfo("waiting for exclusive access to the Nix store for ca drvs...");
lockFile(lockFd.get(), ltWrite, true);
}
if (curCASchema == 0) {
static const char schema[] =
#include "ca-specific-schema.sql.gen.hh"
;
db.exec(schema);
}
writeFile(schemaPath, fmt("%d", nixCASchemaVersion));
lockFile(lockFd.get(), ltRead, true);
}
}
LocalStore::LocalStore(const Params & params)
: StoreConfig(params)
, Store(params)
@ -238,6 +278,10 @@ LocalStore::LocalStore(const Params & params)
else openDB(*state, false);
if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
migrateCASchema(state->db, dbDir + "/ca-schema", globalLock);
}
/* Prepare SQL statements. */
state->stmts->RegisterValidPath.create(state->db,
"insert into ValidPaths (path, hash, registrationTime, deriver, narSize, ultimate, sigs, ca) values (?, ?, ?, ?, ?, ?, ?, ?);");
@ -264,6 +308,28 @@ LocalStore::LocalStore(const Params & params)
state->stmts->QueryPathFromHashPart.create(state->db,
"select path from ValidPaths where path >= ? limit 1;");
state->stmts->QueryValidPaths.create(state->db, "select path from ValidPaths");
if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
state->stmts->RegisterRealisedOutput.create(state->db,
R"(
insert or replace into Realisations (drvPath, outputName, outputPath)
values (?, ?, (select id from ValidPaths where path = ?))
;
)");
state->stmts->QueryRealisedOutput.create(state->db,
R"(
select Output.path from Realisations
inner join ValidPaths as Output on Output.id = Realisations.outputPath
where drvPath = ? and outputName = ?
;
)");
state->stmts->QueryAllRealisedOutputs.create(state->db,
R"(
select outputName, Output.path from Realisations
inner join ValidPaths as Output on Output.id = Realisations.outputPath
where drvPath = ?
;
)");
}
}
@ -301,16 +367,7 @@ std::string LocalStore::getUri()
int LocalStore::getSchema()
{
int curSchema = 0;
if (pathExists(schemaPath)) {
string s = readFile(schemaPath);
if (!string2Int(s, curSchema))
throw Error("'%1%' is corrupt", schemaPath);
}
return curSchema;
}
{ return nix::getSchema(schemaPath); }
void LocalStore::openDB(State & state, bool create)
{
@ -600,13 +657,16 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
void LocalStore::registerDrvOutput(const Realisation & info)
{
auto state(_state.lock());
// XXX: This ignores the references of the output because we can
// recompute them later from the drv and the references of the associated
// store path, but doing so is both inefficient and fragile.
return registerDrvOutput_(*state, queryValidPathId(*state, id.drvPath), id.outputName, info.outPath);
retrySQLite<void>([&]() {
state->stmts->RegisterRealisedOutput.use()
(info.id.drvPath.to_string())
(info.id.outputName)
(printStorePath(info.outPath))
.exec();
});
}
void LocalStore::registerDrvOutput_(State & state, uint64_t deriver, const string & outputName, const StorePath & output)
void LocalStore::cacheDrvOutputMapping(State & state, const uint64_t deriver, const string & outputName, const StorePath & output)
{
retrySQLite<void>([&]() {
state.stmts->AddDerivationOutput.use()
@ -656,7 +716,7 @@ uint64_t LocalStore::addValidPath(State & state,
/* Floating CA derivations have indeterminate output paths until
they are built, so don't register anything in that case */
if (i.second.second)
registerDrvOutput_(state, id, i.first, *i.second.second);
cacheDrvOutputMapping(state, id, i.first, *i.second.second);
}
}
@ -817,71 +877,86 @@ StorePathSet LocalStore::queryValidDerivers(const StorePath & path)
});
}
std::map<std::string, std::optional<StorePath>> LocalStore::queryPartialDerivationOutputMap(const StorePath & path_)
// Try to resolve the derivation at path `original`, with a caching layer
// to make it more efficient
std::optional<StorePath> cachedResolve(
LocalStore & store,
const StorePath & original)
{
auto path = path_;
std::map<std::string, std::optional<StorePath>> outputs;
Derivation drv = readDerivation(path);
for (auto & [outName, _] : drv.outputs) {
outputs.insert_or_assign(outName, std::nullopt);
}
bool haveCached = false;
{
auto resolutions = drvPathResolutions.lock();
auto resolvedPathOptIter = resolutions->find(path);
auto resolvedPathOptIter = resolutions->find(original);
if (resolvedPathOptIter != resolutions->end()) {
auto & [_, resolvedPathOpt] = *resolvedPathOptIter;
if (resolvedPathOpt)
path = *resolvedPathOpt;
haveCached = true;
return resolvedPathOpt;
}
}
/* can't just use else-if instead of `!haveCached` because we need to unlock
`drvPathResolutions` before it is locked in `Derivation::resolve`. */
if (!haveCached && (drv.type() == DerivationType::CAFloating || drv.type() == DerivationType::DeferredInputAddressed)) {
/* Try resolve drv and use that path instead. */
auto attempt = drv.tryResolve(*this);
if (!attempt)
/* If we cannot resolve the derivation, we cannot have any path
assigned so we return the map of all std::nullopts. */
return outputs;
/* Just compute store path */
auto pathResolved = writeDerivation(*this, *std::move(attempt), NoRepair, true);
/* Store in memo table. */
/* FIXME: memo logic should not be local-store specific, should have
wrapper-method instead. */
drvPathResolutions.lock()->insert_or_assign(path, pathResolved);
path = std::move(pathResolved);
}
return retrySQLite<std::map<std::string, std::optional<StorePath>>>([&]() {
auto state(_state.lock());
/* Try resolve drv and use that path instead. */
auto drv = store.readDerivation(original);
auto attempt = drv.tryResolve(store);
if (!attempt)
return std::nullopt;
/* Just compute store path */
auto pathResolved =
writeDerivation(store, *std::move(attempt), NoRepair, true);
/* Store in memo table. */
drvPathResolutions.lock()->insert_or_assign(original, pathResolved);
return pathResolved;
}
std::map<std::string, std::optional<StorePath>>
LocalStore::queryPartialDerivationOutputMap(const StorePath& path_)
{
auto path = path_;
auto outputs = retrySQLite<std::map<std::string, std::optional<StorePath>>>([&]() {
auto state(_state.lock());
std::map<std::string, std::optional<StorePath>> outputs;
uint64_t drvId;
try {
drvId = queryValidPathId(*state, path);
} catch (InvalidPath&) {
/* FIXME? if the derivation doesn't exist, we cannot have a mapping
for it. */
// Ignore non-existing drvs as they might still have an output map
// defined if ca-derivations is enabled
}
auto use(state->stmts->QueryDerivationOutputs.use()(drvId));
while (use.next())
outputs.insert_or_assign(
use.getStr(0), parseStorePath(use.getStr(1)));
return outputs;
});
if (!settings.isExperimentalFeatureEnabled("ca-derivations"))
return outputs;
auto drv = readDerivation(path);
for (auto & output : drv.outputsAndOptPaths(*this)) {
outputs.emplace(output.first, std::nullopt);
}
auto resolvedDrv = cachedResolve(*this, path);
if (!resolvedDrv)
return outputs;
retrySQLite<void>([&]() {
auto state(_state.lock());
path = *resolvedDrv;
auto useQueryDerivationOutputs{
state->stmts->QueryDerivationOutputs.use()
(drvId)
};
state->stmts->QueryAllRealisedOutputs.use()(path.to_string())};
while (useQueryDerivationOutputs.next())
outputs.insert_or_assign(
useQueryDerivationOutputs.getStr(0),
parseStorePath(useQueryDerivationOutputs.getStr(1))
);
parseStorePath(useQueryDerivationOutputs.getStr(1)));
});
return outputs;
});
}
std::optional<StorePath> LocalStore::queryPathFromHashPart(const std::string & hashPart)
{
if (hashPart.size() != StorePath::HashLen) throw Error("invalid hash part");
@ -1615,13 +1690,19 @@ void LocalStore::createUser(const std::string & userName, uid_t userId)
}
}
std::optional<const DrvOutputInfo> LocalStore::queryDrvOutputInfo(const DrvOutputId& id) {
auto outputPath = queryOutputPathOf(id.drvPath, id.outputName);
if (!(outputPath && isValidPath(*outputPath)))
std::optional<const Realisation> LocalStore::queryRealisation(
const DrvOutput& id) {
typedef std::optional<const Realisation> Ret;
return retrySQLite<Ret>([&]() -> Ret {
auto state(_state.lock());
auto use(state->stmts->QueryRealisedOutput.use()(id.drvPath.to_string())(
id.outputName));
if (!use.next())
return std::nullopt;
else
return {DrvOutputInfo{
.outPath = *outputPath,
}};
auto outputPath = parseStorePath(use.getStr(0));
auto resolvedDrv = StorePath(use.getStr(1));
return Ret{
Realisation{.id = id, .outPath = outputPath}};
});
}
} // namespace nix

View file

@ -210,8 +210,8 @@ public:
/* Register the store path 'output' as the output named 'outputName' of
derivation 'deriver'. */
void registerDrvOutput(const DrvOutputId & outputId, const DrvOutputInfo & info) override;
void registerDrvOutput_(State & state, uint64_t deriver, const string & outputName, const StorePath & output);
void registerDrvOutput(const Realisation & info) override;
void cacheDrvOutputMapping(State & state, const uint64_t deriver, const string & outputName, const StorePath & output);
std::optional<const Realisation> queryRealisation(const DrvOutput&) override;

View file

@ -48,7 +48,7 @@ ifneq ($(sandbox_shell),)
libstore_CXXFLAGS += -DSANDBOX_SHELL="\"$(sandbox_shell)\""
endif
$(d)/local-store.cc: $(d)/schema.sql.gen.hh
$(d)/local-store.cc: $(d)/schema.sql.gen.hh $(d)/ca-specific-schema.sql.gen.hh
$(d)/build.cc:
@ -58,7 +58,7 @@ $(d)/build.cc:
@echo ')foo"' >> $@.tmp
@mv $@.tmp $@
clean-files += $(d)/schema.sql.gen.hh
clean-files += $(d)/schema.sql.gen.hh $(d)/ca-specific-schema.sql.gen.hh
$(eval $(call install-file-in, $(d)/nix-store.pc, $(prefix)/lib/pkgconfig, 0644))