Prepare for CA derivation support with lower impact changes

src/hydra-eval-jobs/hydra-eval-jobs.cc

@@ -178,7 +178,11 @@ static void worker(
 
             if (auto drv = getDerivation(state, *v, false)) {
 
-                DrvInfo::Outputs outputs = drv->queryOutputs();
+                // CA derivations do not have static output paths, so we
+                // have to defensively not query output paths in case we
+                // encounter one.
+                DrvInfo::Outputs outputs = drv->queryOutputs(
+                    !experimentalFeatureSettings.isEnabled(Xp::CaDerivations));
 
                 if (drv->querySystem() == "unknown")
                     throw EvalError("derivation must have a 'system' attribute");
@@ -239,12 +243,21 @@ static void worker(
                 }
 
                 nlohmann::json out;
-                for (auto & j : outputs)
-                    // FIXME: handle CA/impure builds.
-                    if (j.second)
-                        out[j.first] = state.store->printStorePath(*j.second);
+                for (auto & [outputName, optOutputPath] : outputs) {
+                    if (optOutputPath) {
+                        out[outputName] = state.store->printStorePath(*optOutputPath);
+                    } else {
+                        // See the `queryOutputs` call above; we should
+                        // not encounter missing output paths otherwise.
+                        assert(experimentalFeatureSettings.isEnabled(Xp::CaDerivations));
+                        // TODO it would be better to set `null` than an
+                        // empty string here, to force the consumer of
+                        // this JSON to more explicitly handle this
+                        // case.
+                        out[outputName] = "";
+                    }
+                }
                 job["outputs"] = std::move(out);
-
                 reply["job"] = std::move(job);
             }
 

src/hydra-queue-runner/build-remote.cc

@@ -228,17 +228,22 @@ static BasicDerivation sendInputs(
     counter & nrStepsCopyingTo
 )
 {
-    BasicDerivation basicDrv(*step.drv);
-
-    for (const auto & [drvPath, node] : step.drv->inputDrvs.map) {
-        auto drv2 = localStore.readDerivation(drvPath);
-        for (auto & name : node.value) {
-            if (auto i = get(drv2.outputs, name)) {
-                auto outPath = i->path(localStore, drv2.name, name);
-                basicDrv.inputSrcs.insert(*outPath);
-            }
-        }
-    }
+    /* Replace the input derivations by their output paths to send a
+       minimal closure to the builder.
+
+       `tryResolve` currently does *not* rewrite input addresses, so it
+       is safe to do this in all cases. (It should probably have a mode
+       to do that, however, but we would not use it here.)
+     */
+    BasicDerivation basicDrv = ({
+        auto maybeBasicDrv = step.drv->tryResolve(destStore, &localStore);
+        if (!maybeBasicDrv)
+            throw Error(
+                "the derivation '%s' can’t be resolved. It’s probably "
+                "missing some outputs",
+                localStore.printStorePath(step.drvPath));
+        *maybeBasicDrv;
+    });
 
     /* Ensure that the inputs exist in the destination store. This is
        a no-op for regular stores, but for the binary cache store,
@@ -319,6 +324,30 @@ static BuildResult performBuild(
         result.stopTime = stopTime;
     }
 
+    // If the protocol was too old to give us `builtOutputs`, initialize
+    // it manually by introspecting the derivation.
+    if (GET_PROTOCOL_MINOR(conn.remoteVersion) < 6)
+    {
+        // If the remote is too old to handle CA derivations, we can’t get this
+        // far anyways
+        assert(drv.type().hasKnownOutputPaths());
+        DerivationOutputsAndOptPaths drvOutputs = drv.outputsAndOptPaths(localStore);
+        // Since this a `BasicDerivation`, `staticOutputHashes` will not
+        // do any real work.
+        auto outputHashes = staticOutputHashes(localStore, drv);
+        for (auto & [outputName, output] : drvOutputs) {
+            auto outputPath = output.second;
+            // We’ve just asserted that the output paths of the derivation
+            // were known
+            assert(outputPath);
+            auto outputHash = outputHashes.at(outputName);
+            auto drvOutput = DrvOutput { outputHash, outputName };
+            result.builtOutputs.insert_or_assign(
+                std::move(outputName),
+                Realisation { drvOutput, *outputPath });
+        }
+    }
+
     return result;
 }
 
@@ -584,6 +613,10 @@ void State::buildRemote(ref<Store> destStore,
             result.logFile = "";
         }
 
+        StorePathSet outputs;
+        for (auto & [_, realisation] : buildResult.builtOutputs)
+            outputs.insert(realisation.outPath);
+
         /* Copy the output paths. */
         if (!machine->isLocalhost() || localStore != std::shared_ptr<Store>(destStore)) {
             updateStep(ssReceivingOutputs);
@@ -592,12 +625,6 @@ void State::buildRemote(ref<Store> destStore,
 
             auto now1 = std::chrono::steady_clock::now();
 
-            StorePathSet outputs;
-            for (auto & i : step->drv->outputsAndOptPaths(*localStore)) {
-                if (i.second.second)
-                   outputs.insert(*i.second.second);
-            }
-
             size_t totalNarSize = 0;
             auto infos = build_remote::queryPathInfos(conn, *localStore, outputs, totalNarSize);
 
@@ -616,6 +643,21 @@ void State::buildRemote(ref<Store> destStore,
             result.overhead += std::chrono::duration_cast<std::chrono::milliseconds>(now2 - now1).count();
         }
 
+        /* Register the outputs of the newly built drv */
+        if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
+            auto outputHashes = staticOutputHashes(*localStore, *step->drv);
+            for (auto & [outputName, realisation] : buildResult.builtOutputs) {
+                // Register the resolved drv output
+                destStore->registerDrvOutput(realisation);
+
+                // Also register the unresolved one
+                auto unresolvedRealisation = realisation;
+                unresolvedRealisation.signatures.clear();
+                unresolvedRealisation.id.drvHash = outputHashes.at(outputName);
+                destStore->registerDrvOutput(unresolvedRealisation);
+            }
+        }
+
         /* Shut down the connection. */
         child.to = -1;
         child.pid.wait();

src/hydra-queue-runner/build-result.cc

@@ -11,18 +11,18 @@ using namespace nix;
 BuildOutput getBuildOutput(
     nix::ref<Store> store,
     NarMemberDatas & narMembers,
-    const Derivation & drv)
+    const OutputPathMap derivationOutputs)
 {
     BuildOutput res;
 
     /* Compute the closure size. */
     StorePathSet outputs;
     StorePathSet closure;
-    for (auto & i : drv.outputsAndOptPaths(*store))
-        if (i.second.second) {
-            store->computeFSClosure(*i.second.second, closure);
-            outputs.insert(*i.second.second);
-        }
+    for (auto& [outputName, outputPath] : derivationOutputs) {
+        store->computeFSClosure(outputPath, closure);
+        outputs.insert(outputPath);
+        res.outputs.insert({outputName, outputPath});
+    }
     for (auto & path : closure) {
         auto info = store->queryPathInfo(path);
         res.closureSize += info->narSize;
@@ -107,13 +107,12 @@ BuildOutput getBuildOutput(
     /* If no build products were explicitly declared, then add all
        outputs as a product of type "nix-build". */
     if (!explicitProducts) {
-        for (auto & [name, output] : drv.outputs) {
+        for (auto & [name, output] : derivationOutputs) {
             BuildProduct product;
-            auto outPath = output.path(*store, drv.name, name);
-            product.path = store->printStorePath(*outPath);
+            product.path = store->printStorePath(output);
             product.type = "nix-build";
             product.subtype = name == "out" ? "" : name;
-            product.name = outPath->name();
+            product.name = output.name();
 
             auto file = narMembers.find(product.path);
             assert(file != narMembers.end());

src/hydra-queue-runner/builder.cc

@@ -223,7 +223,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
 
         if (result.stepStatus == bsSuccess) {
             updateStep(ssPostProcessing);
-            res = getBuildOutput(destStore, narMembers, *step->drv);
+            res = getBuildOutput(destStore, narMembers, destStore->queryDerivationOutputMap(step->drvPath, &*localStore));
         }
     }
 
@@ -277,9 +277,12 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
 
         assert(stepNr);
 
-        for (auto & i : step->drv->outputsAndOptPaths(*localStore)) {
-            if (i.second.second)
-               addRoot(*i.second.second);
+        for (auto & [outputName, optOutputPath] : destStore->queryPartialDerivationOutputMap(step->drvPath, &*localStore)) {
+            if (!optOutputPath)
+                throw Error(
+                    "Missing output %s for derivation %d which was supposed to have succeeded",
+                    outputName, localStore->printStorePath(step->drvPath));
+            addRoot(*optOutputPath);
         }
 
         /* Register success in the database for all Build objects that

src/hydra-queue-runner/hydra-build-result.hh

@@ -36,10 +36,12 @@ struct BuildOutput
 
     std::list<BuildProduct> products;
 
+    std::map<std::string, nix::StorePath> outputs;
+
     std::map<std::string, BuildMetric> metrics;
 };
 
 BuildOutput getBuildOutput(
     nix::ref<nix::Store> store,
     NarMemberDatas & narMembers,
-    const nix::Derivation & drv);
+    const nix::OutputPathMap derivationOutputs);

src/hydra-queue-runner/hydra-queue-runner.cc

@@ -312,10 +312,10 @@ unsigned int State::createBuildStep(pqxx::work & txn, time_t startTime, BuildID
 
     if (r.affected_rows() == 0) goto restart;
 
-    for (auto & [name, output] : step->drv->outputs)
+    for (auto & [name, output] : getDestStore()->queryPartialDerivationOutputMap(step->drvPath, &*localStore))
         txn.exec_params0
             ("insert into BuildStepOutputs (build, stepnr, name, path) values ($1, $2, $3, $4)",
-            buildId, stepNr, name, localStore->printStorePath(*output.path(*localStore, step->drv->name, name)));
+            buildId, stepNr, name, output ? localStore->printStorePath(*output) : "");
 
     if (status == bsBusy)
         txn.exec(fmt("notify step_started, '%d\t%d'", buildId, stepNr));
@@ -352,11 +352,23 @@ void State::finishBuildStep(pqxx::work & txn, const RemoteResult & result,
     assert(result.logFile.find('\t') == std::string::npos);
     txn.exec(fmt("notify step_finished, '%d\t%d\t%s'",
             buildId, stepNr, result.logFile));
+
+    if (result.stepStatus == bsSuccess) {
+        // Update the corresponding `BuildStepOutputs` row to add the output path
+        auto res = txn.exec_params1("select drvPath from BuildSteps where build = $1 and stepnr = $2", buildId, stepNr);
+        assert(res.size());
+        StorePath drvPath = localStore->parseStorePath(res[0].as<std::string>());
+        // If we've finished building, all the paths should be known
+        for (auto & [name, output] : getDestStore()->queryDerivationOutputMap(drvPath, &*localStore))
+            txn.exec_params0
+                ("update BuildStepOutputs set path = $4 where build = $1 and stepnr = $2 and name = $3",
+                  buildId, stepNr, name, localStore->printStorePath(output));
+    }
 }
 
 
 int State::createSubstitutionStep(pqxx::work & txn, time_t startTime, time_t stopTime,
-    Build::ptr build, const StorePath & drvPath, const std::string & outputName, const StorePath & storePath)
+    Build::ptr build, const StorePath & drvPath, const nix::Derivation drv, const std::string & outputName, const StorePath & storePath)
 {
  restart:
     auto stepNr = allocBuildStep(txn, build->id);
@@ -457,6 +469,15 @@ void State::markSucceededBuild(pqxx::work & txn, Build::ptr build,
          res.releaseName != "" ? std::make_optional(res.releaseName) : std::nullopt,
          isCachedBuild ? 1 : 0);
 
+    for (auto & [outputName, outputPath] : res.outputs) {
+        txn.exec_params0
+            ("update BuildOutputs set path = $3 where build = $1 and name = $2",
+             build->id,
+             outputName,
+             localStore->printStorePath(outputPath)
+            );
+    }
+
     txn.exec_params0("delete from BuildProducts where build = $1", build->id);
 
     unsigned int productNr = 1;