From ee9bf7ace79956bf8fb29deb958825cc62e19774 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Wed, 2 Sep 2015 13:42:25 +0200
Subject: [PATCH] Account steps with preferLocalBuild as a separate system type

They will show up in machineTypes as (e.g.) x86_64-linux:local instead
of x86_64-linux. This is to prevent the Hydra provisioner from
creating machines for steps that are supposed to be executed locally.
---
 src/hydra-queue-runner/queue-monitor.cc | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/hydra-queue-runner/queue-monitor.cc b/src/hydra-queue-runner/queue-monitor.cc
index 68635294..c9d21200 100644
--- a/src/hydra-queue-runner/queue-monitor.cc
+++ b/src/hydra-queue-runner/queue-monitor.cc
@@ -332,21 +332,26 @@ Step::ptr State::createStep(std::shared_ptr<StoreAPI> store, const Path & drvPat
        it's not runnable yet, and other threads won't make it
        runnable while step->created == false. */
     step->drv = readDerivation(drvPath);
-    step->systemType = step->drv.platform;
-    {
-        auto i = step->drv.env.find("requiredSystemFeatures");
-        if (i != step->drv.env.end()) {
-            step->requiredSystemFeatures = tokenizeString<std::set<std::string>>(i->second);
-            step->systemType += ":";
-            step->systemType += concatStringsSep(",", step->requiredSystemFeatures);
-        }
-    }
 
     auto attr = step->drv.env.find("preferLocalBuild");
     step->preferLocalBuild =
         attr != step->drv.env.end() && attr->second == "1"
         && has(localPlatforms, step->drv.platform);
 
+    step->systemType = step->drv.platform;
+    {
+        auto i = step->drv.env.find("requiredSystemFeatures");
+        StringSet features;
+        if (i != step->drv.env.end())
+            features = step->requiredSystemFeatures = tokenizeString<std::set<std::string>>(i->second);
+        if (step->preferLocalBuild)
+            features.insert("local");
+        if (!features.empty()) {
+            step->systemType += ":";
+            step->systemType += concatStringsSep(",", features);
+        }
+    }
+
     /* Are all outputs valid? */
     bool valid = true;
     for (auto & i : step->drv.outputs) {