Adapt scheduler to work with dynamic derivations

To avoid dealing with an optional `drvPath` (because we might not know
it yet) everywhere, make an `CreateDerivationAndRealiseGoal`. This goal
just builds/substitutes the derivation file, and then kicks of a build
for that obtained derivation; in other words it does the chaining of
goals when the drv file is missing (as can already be the case) or
computed (new case).

This also means the `getDerivation` state can be removed from
`DerivationGoal`, which makes the `BasicDerivation` / in memory case and
`Derivation` / drv file file case closer together.

src/libstore/build/create-derivation-and-realise-goal.cc

@@ -0,0 +1,158 @@
+#include "create-derivation-and-realise-goal.hh"
+#include "worker.hh"
+
+namespace nix {
+
+CreateDerivationAndRealiseGoal::CreateDerivationAndRealiseGoal(ref<SingleDerivedPath> drvReq,
+ const OutputsSpec & wantedOutputs, Worker & worker, BuildMode buildMode)
+ : Goal(worker, DerivedPath::Built { .drvPath = drvReq, .outputs = wantedOutputs })
+ , drvReq(drvReq)
+ , wantedOutputs(wantedOutputs)
+ , buildMode(buildMode)
+{
+ state = &CreateDerivationAndRealiseGoal::getDerivation;
+ name = fmt(
+ "outer obtaining drv from '%s' and then building outputs %s",
+ drvReq->to_string(worker.store),
+ std::visit(overloaded {
+ [&](const OutputsSpec::All) -> std::string {
+ return "* (all of them)";
+ },
+ [&](const OutputsSpec::Names os) {
+ return concatStringsSep(", ", quoteStrings(os));
+ },
+ }, wantedOutputs.raw()));
+ trace("created outer");
+
+ worker.updateProgress();
+}
+
+
+CreateDerivationAndRealiseGoal::~CreateDerivationAndRealiseGoal()
+{
+}
+
+
+static StorePath pathPartOfReq(const SingleDerivedPath & req)
+{
+ return std::visit(overloaded {
+ [&](const SingleDerivedPath::Opaque & bo) {
+ return bo.path;
+ },
+ [&](const SingleDerivedPath::Built & bfd) {
+ return pathPartOfReq(*bfd.drvPath);
+ },
+ }, req.raw());
+}
+
+
+std::string CreateDerivationAndRealiseGoal::key()
+{
+ /* Ensure that derivations get built in order of their name,
+ i.e. a derivation named "aardvark" always comes before "baboon". And
+ substitution goals and inner derivation goals always happen before
+ derivation goals (due to "b$"). */
+ return "c$" + std::string(pathPartOfReq(*drvReq).name()) + "$" + drvReq->to_string(worker.store);
+}
+
+
+void CreateDerivationAndRealiseGoal::timedOut(Error && ex)
+{
+}
+
+
+void CreateDerivationAndRealiseGoal::work()
+{
+ (this->*state)();
+}
+
+
+void CreateDerivationAndRealiseGoal::addWantedOutputs(const OutputsSpec & outputs)
+{
+ /* If we already want all outputs, there is nothing to do. */
+ auto newWanted = wantedOutputs.union_(outputs);
+ bool needRestart = !newWanted.isSubsetOf(wantedOutputs);
+ wantedOutputs = newWanted;
+
+ if (!needRestart) return;
+
+ if (!optDrvPath)
+ // haven't started steps where the outputs matter yet
+ return;
+ worker.makeDerivationGoal(*optDrvPath, outputs, buildMode);
+}
+
+
+void CreateDerivationAndRealiseGoal::getDerivation()
+{
+ trace("outer init");
+
+ /* The first thing to do is to make sure that the derivation
+ exists. If it doesn't, it may be created through a
+ substitute. */
+ {
+ if (buildMode != bmNormal) goto load;
+
+ auto drvPath = StorePath::dummy;
+ try {
+ drvPath = resolveDerivedPath(worker.store, *drvReq);
+ } catch (MissingRealisation) {
+ goto load;
+ }
+ if (!worker.evalStore.isValidPath(drvPath) && !worker.store.isValidPath(drvPath))
+ goto load;
+
+ trace(fmt("already have drv '%s' for '%s', can go straight to building",
+ worker.store.printStorePath(drvPath),
+ drvReq->to_string(worker.store)));
+
+ loadAndBuildDerivation();
+ return;
+ }
+
+load:
+ trace("need to obtain drv we want to build");
+
+ addWaitee(worker.makeGoal(DerivedPath::fromSingle(*drvReq)));
+
+ state = &CreateDerivationAndRealiseGoal::loadAndBuildDerivation;
+ if (waitees.empty()) work();
+}
+
+
+void CreateDerivationAndRealiseGoal::loadAndBuildDerivation()
+{
+ trace("outer load and build derivation");
+
+ if (nrFailed != 0) {
+ amDone(ecFailed, Error("cannot build missing derivation '%s'", drvReq->to_string(worker.store)));
+ return;
+ }
+
+ StorePath drvPath = resolveDerivedPath(worker.store, *drvReq);
+ /* Build this step! */
+ concreteDrvGoal = worker.makeDerivationGoal(drvPath, wantedOutputs, buildMode);
+ addWaitee(upcast_goal(concreteDrvGoal));
+ state = &CreateDerivationAndRealiseGoal::buildDone;
+ optDrvPath = std::move(drvPath);
+ if (waitees.empty()) work();
+}
+
+
+void CreateDerivationAndRealiseGoal::buildDone()
+{
+ trace("outer build done");
+
+ buildResult = upcast_goal(concreteDrvGoal)->getBuildResult(DerivedPath::Built {
+ .drvPath = drvReq,
+ .outputs = wantedOutputs,
+ });
+
+ if (buildResult.success())
+ amDone(ecSuccess);
+ else
+ amDone(ecFailed, Error("building '%s' failed", drvReq->to_string(worker.store)));
+}
+
+
+}

src/libstore/build/create-derivation-and-realise-goal.hh

@@ -0,0 +1,78 @@
+#pragma once
+
+#include "parsed-derivations.hh"
+#include "lock.hh"
+#include "store-api.hh"
+#include "pathlocks.hh"
+#include "goal.hh"
+
+namespace nix {
+
+struct DerivationGoal;
+
+struct CreateDerivationAndRealiseGoal : public Goal
+{
+ /**
+ * How to obtain a store path of the derivation to build.
+ */
+ ref<SingleDerivedPath> drvReq;
+
+ /**
+ * The path of the derivation, once obtained.
+ **/
+ std::optional<StorePath> optDrvPath;
+
+ /**
+ * The goal for the corresponding concrete derivation.
+ **/
+ std::shared_ptr<DerivationGoal> concreteDrvGoal;
+
+ /**
+ * The specific outputs that we need to build.
+ */
+ OutputsSpec wantedOutputs;
+
+ typedef void (CreateDerivationAndRealiseGoal::*GoalState)();
+ GoalState state;
+
+ /**
+ * The final output paths of the build.
+ *
+ * - For input-addressed derivations, always the precomputed paths
+ *
+ * - For content-addressed derivations, calcuated from whatever the
+ * hash ends up being. (Note that fixed outputs derivations that
+ * produce the "wrong" output still install that data under its
+ * true content-address.)
+ */
+ OutputPathMap finalOutputs;
+
+ BuildMode buildMode;
+
+ CreateDerivationAndRealiseGoal(ref<SingleDerivedPath> drvReq,
+ const OutputsSpec & wantedOutputs, Worker & worker,
+ BuildMode buildMode = bmNormal);
+ virtual ~CreateDerivationAndRealiseGoal();
+
+ void timedOut(Error && ex) override;
+
+ std::string key() override;
+
+ void work() override;
+
+ /**
+ * Add wanted outputs to an already existing derivation goal.
+ */
+ void addWantedOutputs(const OutputsSpec & outputs);
+
+ /**
+ * The states.
+ */
+ void getDerivation();
+ void loadAndBuildDerivation();
+ void buildDone();
+
+ JobCategory jobCategory() override { return JobCategory::Build; };
+};
+
+}

src/libstore/build/derivation-goal.cc

@@ -71,7 +71,7 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath,
  , wantedOutputs(wantedOutputs)
  , buildMode(buildMode)
 {
- state = &DerivationGoal::getDerivation;
+ state = &DerivationGoal::loadDerivation;
  name = fmt(
  "building of '%s' from .drv file",
  DerivedPath::Built { makeConstantStorePathRef(drvPath), wantedOutputs }.to_string(worker.store));
@@ -164,24 +164,6 @@ void DerivationGoal::addWantedOutputs(const OutputsSpec & outputs)
 }
 
 
-void DerivationGoal::getDerivation()
-{
- trace("init");
-
- /* The first thing to do is to make sure that the derivation
- exists. If it doesn't, it may be created through a
- substitute. */
- if (buildMode == bmNormal && worker.evalStore.isValidPath(drvPath)) {
- loadDerivation();
- return;
- }
-
- addWaitee(upcast_goal(worker.makePathSubstitutionGoal(drvPath)));
-
- state = &DerivationGoal::loadDerivation;
-}
-
-
 void DerivationGoal::loadDerivation()
 {
  trace("loading derivation");
@@ -1485,6 +1467,11 @@ void DerivationGoal::done(
  amDone(buildResult.success() ? ecSuccess : ecFailed, std::move(ex));
 }
 
+}
+
+#include "create-derivation-and-realise-goal.hh"
+
+namespace nix {
 
 void DerivationGoal::waiteeDone(GoalPtr waitee, ExitCode result)
 {
@@ -1493,8 +1480,11 @@ void DerivationGoal::waiteeDone(GoalPtr waitee, ExitCode result)
  if (!useDerivation) return;
  auto & fullDrv = *dynamic_cast<Derivation *>(drv.get());
 
- auto * dg = dynamic_cast<DerivationGoal *>(&*waitee);
- if (!dg) return;
+ auto * odg = dynamic_cast<CreateDerivationAndRealiseGoal *>(&*waitee);
+ if (!odg) return;
+ auto * dg = &*odg->concreteDrvGoal;
+ // By the time we get here, the outer goals should have.
+ assert(dg);
 
  auto outputs = fullDrv.inputDrvs.find(dg->drvPath);
  if (outputs == fullDrv.inputDrvs.end()) return;

src/libstore/build/derivation-goal.hh

@@ -66,8 +66,7 @@ struct DerivationGoal : public Goal
  std::shared_ptr<DerivationGoal> resolvedDrvGoal;
 
  /**
- * The specific outputs that we need to build. Empty means all of
- * them.
+ * The specific outputs that we need to build.
  */
  OutputsSpec wantedOutputs;
 
@@ -229,7 +228,6 @@ struct DerivationGoal : public Goal
  /**
  * The states.
  */
- void getDerivation();
  void loadDerivation();
  void haveDerivation();
  void outputsSubstitutionTried();

src/libstore/build/entry-points.cc

@@ -1,5 +1,6 @@
 #include "worker.hh"
 #include "substitution-goal.hh"
+#include "create-derivation-and-realise-goal.hh"
 #include "derivation-goal.hh"
 #include "local-store.hh"
 
@@ -15,7 +16,7 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
 
  worker.run(goals);
 
- StorePathSet failed;
+ StringSet failed;
  std::optional<Error> ex;
  for (auto & i : goals) {
  if (i->ex) {
@@ -25,8 +26,10 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
  ex = std::move(i->ex);
  }
  if (i->exitCode != Goal::ecSuccess) {
- if (auto i2 = dynamic_cast<DerivationGoal *>(i.get())) failed.insert(i2->drvPath);
- else if (auto i2 = dynamic_cast<PathSubstitutionGoal *>(i.get())) failed.insert(i2->storePath);
+ if (auto i2 = dynamic_cast<CreateDerivationAndRealiseGoal *>(i.get()))
+ failed.insert(i2->drvReq->to_string(*this));
+ else if (auto i2 = dynamic_cast<PathSubstitutionGoal *>(i.get()))
+ failed.insert(printStorePath(i2->storePath));
  }
  }
 
@@ -35,7 +38,7 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
  throw std::move(*ex);
  } else if (!failed.empty()) {
  if (ex) logError(ex->info());
- throw Error(worker.failingExitStatus(), "build of %s failed", showPaths(failed));
+ throw Error(worker.failingExitStatus(), "build of %s failed", concatStringsSep(", ", quoteStrings(failed)));
  }
 }