From ea1eb2e3fbf337ce64deb212c98bfc6aceee0ffc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 17 Aug 2015 14:37:57 +0200
Subject: [PATCH] Keep track of requiredSystemFeatures in the machine stats

For example, steps that require the "kvm" feature may require a
different kind of machine to be provisioned. This can also be used to
require performance-sensitive tests to run on a particular kind of
machine, e.g., by setting requiredSystemFeatures to something like
"ec2-i2.8xlarge".
---
 src/hydra-queue-runner/dispatcher.cc    | 10 +++++-----
 src/hydra-queue-runner/queue-monitor.cc |  6 +++++-
 src/hydra-queue-runner/state.hh         |  1 +
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/hydra-queue-runner/dispatcher.cc b/src/hydra-queue-runner/dispatcher.cc
index ecc68116..d6a02d4a 100644
--- a/src/hydra-queue-runner/dispatcher.cc
+++ b/src/hydra-queue-runner/dispatcher.cc
@@ -158,7 +158,7 @@ system_time State::doDispatch()
 
                 ++i;
 
-                runnablePerType[step->drv.platform]++;
+                runnablePerType[step->systemType]++;
 
                 /* Skip previously failed steps that aren't ready
                    to be retried. */
@@ -219,8 +219,8 @@ system_time State::doDispatch()
                             break;
                         } else ++i;
                     assert(removed);
-                    assert(runnablePerType[step->drv.platform]);
-                    runnablePerType[step->drv.platform]--;
+                    assert(runnablePerType[step->systemType]);
+                    runnablePerType[step->systemType]--;
                 }
 
                 /* Make a slot reservation and start a thread to
@@ -291,7 +291,7 @@ State::MachineReservation::MachineReservation(State & state, Step::ptr step, Mac
 
     {
         auto machineTypes_(state.machineTypes.lock());
-        (*machineTypes_)[step->drv.platform].running++;
+        (*machineTypes_)[step->systemType].running++;
     }
 }
 
@@ -305,7 +305,7 @@ State::MachineReservation::~MachineReservation()
 
     {
         auto machineTypes_(state.machineTypes.lock());
-        auto & machineType = (*machineTypes_)[step->drv.platform];
+        auto & machineType = (*machineTypes_)[step->systemType];
         assert(machineType.running);
         machineType.running--;
         if (machineType.running == 0)
diff --git a/src/hydra-queue-runner/queue-monitor.cc b/src/hydra-queue-runner/queue-monitor.cc
index 3be08897..bad6dabf 100644
--- a/src/hydra-queue-runner/queue-monitor.cc
+++ b/src/hydra-queue-runner/queue-monitor.cc
@@ -359,10 +359,14 @@ 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())
+        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");
diff --git a/src/hydra-queue-runner/state.hh b/src/hydra-queue-runner/state.hh
index db81a290..7d376b70 100644
--- a/src/hydra-queue-runner/state.hh
+++ b/src/hydra-queue-runner/state.hh
@@ -135,6 +135,7 @@ struct Step
     nix::Derivation drv;
     std::set<std::string> requiredSystemFeatures;
     bool preferLocalBuild;
+    std::string systemType; // concatenation of drv.platform and requiredSystemFeatures
 
     struct State
     {