libstore: hide Worker goal factory methods

this doesn't serve a great purpose yet except to confine construction of
goals to the stack frame of Worker::run() and its child frames. we don't
need this yet (and the goal constructors remain fully visible), but in a
future change that fully removes the current worker loop we'll need some
way of knowing which goals are top-level goals without passing the goals
themselves around. once that's possible we can remove visible goals as a
concept and rely on build result futures and a scheduler built upon them

Change-Id: Ia73cdeffcfb9ba1ce9d69b702dc0bc637a4c4ce6

1 files changed, 4 insertions, 1 deletions

diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index 9e548cc16..5d0cc920a 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -326,8 +326,9 @@ void Worker::waitForAWhile(GoalPtr goal)
 }
 
 
-void Worker::run(const Goals & _topGoals)
+Goals Worker::run(std::function<Goals (GoalFactory &)> req)
 {
+    auto _topGoals = req(goalFactory());
     std::vector<nix::DerivedPath> topPaths;
 
     assert(!running);
@@ -411,6 +412,8 @@ void Worker::run(const Goals & _topGoals)
     assert(!settings.keepGoing || awake.empty());
     assert(!settings.keepGoing || wantingToBuild.empty());
     assert(!settings.keepGoing || children.empty());
+
+    return _topGoals;
 }
 
 void Worker::waitForInput()