libstore: create drv temp roots in Worker

constructors can't be async, and root creation must be made async.
creating roots outside of goal classes and passing a witness type
is a lot easier than changing the constructor structure of today.

Change-Id: Ic84a92f3db2e1a9a9164047456f227048c6871bd

lix/libstore/build/derivation-goal.cc

@@ -82,7 +82,7 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath,
 }
 
 
-DerivationGoal::DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
+DerivationGoal::DerivationGoal(DrvHasRoot, const StorePath & drvPath, const BasicDerivation & drv,
     const OutputsSpec & wantedOutputs, Worker & worker, bool isDependency, BuildMode buildMode)
     : Goal(worker, isDependency)
     , useDerivation(false)
@@ -98,10 +98,6 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath, const BasicDerivation
     trace("created");
 
     mcExpectedBuilds = worker.expectedBuilds.addTemporarily(1);
-
-    /* Prevent the .chroot directory from being
-       garbage-collected. (See isActiveTempFile() in gc.cc.) */
-    worker.store.addTempRoot(this->drvPath);
 }
 
 

lix/libstore/build/derivation-goal.hh

@@ -245,10 +245,13 @@ struct DerivationGoal : public Goal
      */
     std::string machineName;
 
+    /** Witness type to say that the drvPath has already been added as a temp root */
+    struct DrvHasRoot { explicit DrvHasRoot() = default; };
+
     DerivationGoal(const StorePath & drvPath,
         const OutputsSpec & wantedOutputs, Worker & worker, bool isDependency,
         BuildMode buildMode = bmNormal);
-    DerivationGoal(const StorePath & drvPath, const BasicDerivation & drv,
+    DerivationGoal(DrvHasRoot, const StorePath & drvPath, const BasicDerivation & drv,
         const OutputsSpec & wantedOutputs, Worker & worker, bool isDependency,
         BuildMode buildMode = bmNormal);
     virtual ~DerivationGoal() noexcept(false);

lix/libstore/build/local-derivation-goal.hh

@@ -195,6 +195,7 @@ struct LocalDerivationGoal : public DerivationGoal
      * possibly a platform-specific subclass
      */
     static std::unique_ptr<LocalDerivationGoal> makeLocalDerivationGoal(
+        DrvHasRoot drvRoot,
         const StorePath & drvPath,
         const BasicDerivation & drv,
         const OutputsSpec & wantedOutputs,

lix/libstore/build/worker.cc

@@ -142,16 +142,20 @@ std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<Result<Goal::WorkResult>>
     BuildMode buildMode
 )
 {
+    /* Prevent the .chroot directory from being
+       garbage-collected. (See isActiveTempFile() in gc.cc.) */
+    store.addTempRoot(drvPath);
+
     return makeGoalCommon(
         derivationGoals,
         drvPath,
         [&]() -> std::unique_ptr<DerivationGoal> {
             return !dynamic_cast<LocalStore *>(&store)
                 ? std::make_unique<DerivationGoal>(
-                    drvPath, drv, wantedOutputs, *this, running, buildMode
+                    DerivationGoal::DrvHasRoot{}, drvPath, drv, wantedOutputs, *this, running, buildMode
                 )
                 : LocalDerivationGoal::makeLocalDerivationGoal(
-                    drvPath, drv, wantedOutputs, *this, running, buildMode
+                    DerivationGoal::DrvHasRoot{}, drvPath, drv, wantedOutputs, *this, running, buildMode
                 );
         },
         [&](DerivationGoal & g) { return g.addWantedOutputs(wantedOutputs); }

lix/libstore/platform.cc

@@ -45,6 +45,7 @@ std::unique_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
 }
 
 std::unique_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoal(
+    DrvHasRoot drvRoot,
     const StorePath & drvPath,
     const BasicDerivation & drv,
     const OutputsSpec & wantedOutputs,
@@ -55,19 +56,19 @@ std::unique_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
 {
 #if __linux__
     return std::make_unique<LinuxLocalDerivationGoal>(
-        drvPath, drv, wantedOutputs, worker, isDependency, buildMode
+        drvRoot, drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #elif __APPLE__
     return std::make_unique<DarwinLocalDerivationGoal>(
-        drvPath, drv, wantedOutputs, worker, isDependency, buildMode
+        drvRoot, drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #elif __FreeBSD__
     return std::make_unique<FreeBSDLocalDerivationGoal>(
-        drvPath, drv, wantedOutputs, worker, isDependency, buildMode
+        drvRoot, drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #else
     return std::make_unique<FallbackLocalDerivationGoal>(
-        drvPath, drv, wantedOutputs, worker, isDependency, buildMode
+        drvRoot, drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #endif
 }