libstore: turn Goal::WaitForGoals into a promise

also gets rid of explicit strong references to dependencies of any goal,
and weak references to dependers as well. those are now only held within
promises representing goal completion and thus independent of the goal's
relation to each other. the weak references to dependers was only needed
for notifications, and that's much better handled entirely by kj itself.

Change-Id: I00d06df9090f8d6336ee4bb0c1313a7052fb016b

1 files changed, 19 insertions, 11 deletions

diff --git a/src/libstore/build/entry-points.cc b/src/libstore/build/entry-points.cc
index a0f18a02c..27c341295 100644
--- a/src/libstore/build/entry-points.cc
+++ b/src/libstore/build/entry-points.cc
@@ -17,9 +17,9 @@ void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMod
     Worker worker(*this, evalStore ? *evalStore : *this, aio);
 
     auto goals = runWorker(worker, [&](GoalFactory & gf) {
-        Goals goals;
+        Worker::Targets goals;
         for (auto & br : reqs)
-            goals.insert(gf.makeGoal(br, buildMode));
+            goals.emplace(gf.makeGoal(br, buildMode));
         return goals;
     });
 
@@ -60,11 +60,11 @@ std::vector<KeyedBuildResult> Store::buildPathsWithResults(
     std::vector<std::pair<const DerivedPath &, GoalPtr>> state;
 
     auto goals = runWorker(worker, [&](GoalFactory & gf) {
-        Goals goals;
+        Worker::Targets goals;
         for (const auto & req : reqs) {
             auto goal = gf.makeGoal(req, buildMode);
-            goals.insert(goal);
-            state.push_back({req, goal});
+            state.push_back({req, goal.first});
+            goals.emplace(std::move(goal));
         }
         return goals;
     });
@@ -84,8 +84,10 @@ BuildResult Store::buildDerivation(const StorePath & drvPath, const BasicDerivat
     Worker worker(*this, *this, aio);
 
     try {
-        auto goals = runWorker(worker, [&](GoalFactory & gf) -> Goals {
-            return Goals{gf.makeBasicDerivationGoal(drvPath, drv, OutputsSpec::All{}, buildMode)};
+        auto goals = runWorker(worker, [&](GoalFactory & gf) {
+            Worker::Targets goals;
+            goals.emplace(gf.makeBasicDerivationGoal(drvPath, drv, OutputsSpec::All{}, buildMode));
+            return goals;
         });
         auto goal = *goals.begin();
         return goal->buildResult.restrictTo(DerivedPath::Built {
@@ -110,7 +112,9 @@ void Store::ensurePath(const StorePath & path)
     Worker worker(*this, *this, aio);
 
     auto goals = runWorker(worker, [&](GoalFactory & gf) {
-        return Goals{gf.makePathSubstitutionGoal(path)};
+        Worker::Targets goals;
+        goals.emplace(gf.makePathSubstitutionGoal(path));
+        return goals;
     });
     auto goal = *goals.begin();
 
@@ -130,7 +134,9 @@ void Store::repairPath(const StorePath & path)
     Worker worker(*this, *this, aio);
 
     auto goals = runWorker(worker, [&](GoalFactory & gf) {
-        return Goals{gf.makePathSubstitutionGoal(path, Repair)};
+        Worker::Targets goals;
+        goals.emplace(gf.makePathSubstitutionGoal(path, Repair));
+        return goals;
     });
     auto goal = *goals.begin();
 
@@ -140,14 +146,16 @@ void Store::repairPath(const StorePath & path)
         auto info = queryPathInfo(path);
         if (info->deriver && isValidPath(*info->deriver)) {
             worker.run([&](GoalFactory & gf) {
-                return Goals{gf.makeGoal(
+                Worker::Targets goals;
+                goals.emplace(gf.makeGoal(
                     DerivedPath::Built{
                         .drvPath = makeConstantStorePathRef(*info->deriver),
                         // FIXME: Should just build the specific output we need.
                         .outputs = OutputsSpec::All{},
                     },
                     bmRepair
-                )};
+                ));
+                return goals;
             });
         } else
             throw Error(worker.failingExitStatus(), "cannot repair path '%s'", printStorePath(path));