From ed218e1d6cf755fc3011c0954eb7031f95d3d732 Mon Sep 17 00:00:00 2001
From: Alexander Bantyev <balsoft@balsoft.ru>
Date: Fri, 25 Sep 2020 00:07:42 +0300
Subject: [PATCH] Fix max-jobs option

After 0ed946aa616bbf7ffe7f90d3309abdd27d875b10, max-jobs setting (-j/--max-jobs)
stopped working.

The reason was that nrLocalBuilds (which compared to maxBuildJobs to figure
out whether the limit is reached or not) is not incremented yet when tryBuild
is started; So, the solution is to move the check to tryLocalBuild.

Closes https://github.com/nixos/nix/issues/3763
---
 src/libstore/build.cc | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index db7dbc17e..3fc24b221 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1612,6 +1612,13 @@ void DerivationGoal::tryToBuild()
 
     actLock.reset();
 
+    state = &DerivationGoal::tryLocalBuild;
+    worker.wakeUp(shared_from_this());
+}
+
+void DerivationGoal::tryLocalBuild() {
+    bool buildLocally = buildMode != bmNormal || parsedDrv->willBuildLocally(worker.store);
+
     /* Make sure that we are allowed to start a build.  If this
        derivation prefers to be done locally, do it even if
        maxBuildJobs is 0. */
@@ -1622,12 +1629,6 @@ void DerivationGoal::tryToBuild()
         return;
     }
 
-    state = &DerivationGoal::tryLocalBuild;
-    worker.wakeUp(shared_from_this());
-}
-
-void DerivationGoal::tryLocalBuild() {
-
     /* If `build-users-group' is not empty, then we have to build as
        one of the members of that group. */
     if (settings.buildUsersGroup != "" && getuid() == 0) {