libstore: remove Goal::StillAlive

this was a triumph. i'm making a note here: huge success. it's hard to
overstate my satisfaction! i'm not even angry. i'm being so sincere ri

actually, no. we *are* angry. this was one dumbass odyssey. nobody has
asked for this. but not doing it would have locked us into old, broken
protocols forever or (possibly worse) forced us to write our own async
framework building on the old did-you-mean-continuations in Worker. if
we had done that we'd be locked into ever more, and ever more complex,
manual state management all over the place. this just could not stand.

Change-Id: I43a6de1035febff59d2eff83be9ad52af4659871

1 files changed, 4 insertions, 16 deletions

diff --git a/src/libstore/build/goal.hh b/src/libstore/build/goal.hh
index 17c3d85db..03c2cf309 100644
--- a/src/libstore/build/goal.hh
+++ b/src/libstore/build/goal.hh
@@ -99,11 +99,7 @@ protected:
     AsyncSemaphore::Token slotToken;
 
 public:
-
-    struct Finished;
-
-    struct [[nodiscard]] StillAlive {};
-    struct [[nodiscard]] Finished {
+    struct [[nodiscard]] WorkResult {
         ExitCode exitCode;
         BuildResult result;
         std::shared_ptr<Error> ex;
@@ -113,21 +109,13 @@ public:
         bool checkMismatch = false;
     };
 
-    struct [[nodiscard]] WorkResult : std::variant<
-                                          StillAlive,
-                                          Finished>
-    {
-        WorkResult() = delete;
-        using variant::variant;
-    };
-
 protected:
-    kj::Promise<Result<WorkResult>> waitForAWhile();
-    kj::Promise<Result<WorkResult>>
+    kj::Promise<void> waitForAWhile();
+    kj::Promise<Result<void>>
     waitForGoals(kj::Array<std::pair<GoalPtr, kj::Promise<void>>> dependencies) noexcept;
 
     template<std::derived_from<Goal>... G>
-    kj::Promise<Result<Goal::WorkResult>>
+    kj::Promise<Result<void>>
     waitForGoals(std::pair<std::shared_ptr<G>, kj::Promise<void>>... goals) noexcept
     {
         return waitForGoals(kj::arrOf<std::pair<GoalPtr, kj::Promise<void>>>(std::move(goals)...));