libstore: add explicit in-build-slot-ness to goals

we don't need to expose information about how busy a Worker is if the
worker can instead tell its work items whether they are in a slot. in
the future we might use this to not start items waiting for a slot if
no slots are currently available, but that requires more preparation.

Change-Id: Ibe01ac536da7e6d6f80520164117c43e772f9bd9

1 files changed, 2 insertions, 3 deletions

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 8e184b9bc..841d1f2f6 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -150,14 +150,13 @@ void LocalDerivationGoal::killSandbox(bool getStats)
 }
 
 
-Goal::WorkResult LocalDerivationGoal::tryLocalBuild()
+Goal::WorkResult LocalDerivationGoal::tryLocalBuild(bool inBuildSlot)
 {
 #if __APPLE__
     additionalSandboxProfile = parsedDrv->getStringAttr("__sandboxProfile").value_or("");
 #endif
 
-    unsigned int curBuilds = worker.getNrLocalBuilds();
-    if (curBuilds >= settings.maxBuildJobs) {
+    if (!inBuildSlot) {
         state = &DerivationGoal::tryToBuild;
         outputLocks.unlock();
         return WaitForSlot{};