Evaluator cleanups

* Don't use isCurrent anymore; instead look up builds in the previous
  jobset evaluation.  (The isCurrent field is still maintained because
  it's still used in some other places.)

* To determine whether to perform an evaluation, compare the hash of
  the current inputs with the inputs of the previous jobset
  evaluation, rather than checking if there was ever an evaluation
  with those inputs.  This way, if the inputs of an evaluation change
  back to a previous state, we get a new jobset evaluation in the
  database (and thus the latest jobset evaluation correctly represents
  the latest state of the jobset).

* Improve performance by removing some unnecessary operations and
  adding an index.

src/lib/Hydra/Controller/Build.pm

@@ -538,7 +538,7 @@ sub clone_submit : Chained('build') PathPart('clone/submit') Args(0) {
     my %currentBuilds;
     my $newBuild = checkBuild(
         $c->model('DB'), $build->project, $build->jobset,
-        $inputInfo, $nixExprInput, $job, \%currentBuilds);
+        $inputInfo, $nixExprInput, $job, \%currentBuilds, undef);
 
     error($c, "This build has already been performed.") unless $newBuild;
     

src/lib/Hydra/Helper/AddBuilds.pm

@@ -17,6 +17,7 @@ our @ISA = qw(Exporter);
 our @EXPORT = qw(
     fetchInput evalJobs checkBuild inputsToArgs captureStdoutStderr 
     getReleaseName getBuildLog addBuildProducts restartBuild scmPath
+    getPrevJobsetEval
 );
 
 
@@ -787,9 +788,18 @@ sub addBuildProducts {
 }
 
 
+# Return the most recent evaluation of the given jobset that had new
+# builds, or undefined if no such evaluation exists.
+sub getPrevJobsetEval {
+    my ($db, $jobset) = @_;
+    my ($prevEval) = $jobset->jobsetevals({ hasnewbuilds => 1 }, { order_by => "id DESC", rows => 1 });
+    return $prevEval;
+}
+
+
 # Check whether to add the build described by $buildInfo.
 sub checkBuild {
-    my ($db, $project, $jobset, $inputInfo, $nixExprInput, $buildInfo, $currentBuilds) = @_;
+    my ($db, $project, $jobset, $inputInfo, $nixExprInput, $buildInfo, $buildIds, $prevEval) = @_;
 
     my $jobName = $buildInfo->{jobName};
     my $drvPath = $buildInfo->{drvPath};
@@ -822,19 +832,36 @@ sub checkBuild {
         # !!! Checking $outPath doesn't take meta-attributes into
         # account.  For instance, do we want a new build to be
         # scheduled if the meta.maintainers field is changed?
-        my @previousBuilds = $job->builds->search({outPath => $outPath, isCurrent => 1});
-        if (scalar(@previousBuilds) > 0) {
-            print STDERR "already scheduled/built\n";
-            $currentBuilds->{$_->id} = 0 foreach @previousBuilds;
-            return;
+        if (defined $prevEval) {
+            my ($prevBuild) = $prevEval->builds->search({ job => $job->name, outPath => $outPath }, { rows => 1, columns => ['id'] });
+            if (defined $prevBuild) {
+                print STDERR "    already scheduled/built as build ", $prevBuild->id, "\n";
+                $buildIds->{$prevBuild->id} = 0;
+                return;
+            }
         }
         
         my $time = time();
         
         # Nope, so add it.
+        my %extraFlags;
+        if (isValidPath($outPath)) {
+            %extraFlags =
+                ( finished => 1 
+                , iscachedbuild => 1
+                , buildstatus => 0
+                , starttime => $time 
+                , stoptime => $time 
+                , logfile => getBuildLog($drvPath)
+                , errormsg => ""
+                , releasename => getReleaseName($outPath)
+                );
+        } else {
+            %extraFlags = ( finished => 0 );
+        }
+	
         $build = $job->builds->create(
-            { finished => 0
-            , timestamp => $time 
+            { timestamp => $time 
             , description => $buildInfo->{description}
             , longdescription => $buildInfo->{longDescription}
             , license => $buildInfo->{license}
@@ -849,30 +876,19 @@ sub checkBuild {
             , iscurrent => 1
             , nixexprinput => $jobset->nixexprinput
             , nixexprpath => $jobset->nixexprpath
+	    , priority => $priority
+	    , busy => 0
+	    , locker => ""
+	    , %extraFlags
             });
 
-        $currentBuilds->{$build->id} = 1;
+        $buildIds->{$build->id} = 1;
         
-        if (isValidPath($outPath)) {
-            print STDERR "marked as cached build ", $build->id, "\n";
-	    $build->update(
-                { finished => 1 
-                , iscachedbuild => 1
-                , buildstatus => 0
-                , starttime => $time 
-                , stoptime => $time 
-                , logfile => getBuildLog($drvPath)
-                , errormsg => ""
-                , releasename => getReleaseName($outPath)
-                });
+        if ($build->iscachedbuild) {
+            print STDERR "    marked as cached build ", $build->id, "\n";
             addBuildProducts($db, $build);
         } else {
-            print STDERR "added to queue as build ", $build->id, "\n";
-	    $build->update(
-		{ priority => $priority
-                , busy => 0
-                , locker => ""
-                });
+            print STDERR "    added to queue as build ", $build->id, "\n";
         }
 
         my %inputs;

src/lib/Hydra/Schema/JobsetEvals.pm

@@ -161,5 +161,4 @@ __PACKAGE__->has_many(
 
 __PACKAGE__->many_to_many(builds => 'buildIds', 'build');
 
-# You can replace this text with custom content, and it will be preserved on regeneration
 1;