Use swarming in create_pagesets CT task

ct/go/util/util.go

Index: ct/go/util/util.go
diff --git a/ct/go/util/util.go b/ct/go/util/util.go
index e69499571e5931fd2e1900fa47f49b38c967c093..4fe5e885e89d7e9bc204289066f7cb69cd1d0944 100644
--- a/ct/go/util/util.go
+++ b/ct/go/util/util.go
@@ -16,6 +16,7 @@ import (
 	"time"
 
 	"go.skia.org/infra/go/exec"
+	"go.skia.org/infra/go/swarming"
 	"go.skia.org/infra/go/util"
 
 	"github.com/skia-dev/glog"
@@ -390,3 +391,48 @@ func ValidateSKPs(pathToSkps string) error {
 
 	return nil
 }
+
+// GetStartRange returns the range worker should start processing at based on its num and how many
+// artifacts it is allowed to process.
+func GetStartRange(workerNum, artifactsPerWorker int) int {
+	return ((workerNum - 1) * artifactsPerWorker) + 1
+}
+
+// ArchiveTriggerCollectSwarmingTasks is a convenience function for CT scripts to call to
+// batch archive isolates, trigger swarming tasks, collect the triggered swarming tasks.
+func ArchiveTriggerCollectSwarmingTask(s *swarming.SwarmingClient, taskNames, genJSONs []string, hardTimeout, ioTimeout time.Duration) error {

[dogben, 2016/05/18 17:38:26]

Seems that taskNames is only used to verify tasksToHashes, but you could use
genJSONs for that purpose.

If you remove taskNames here, you can also simplify the code in
create_pagesets_on_workers.

[rmistry, 2016/05/19 12:59:50]

Keeping the taskNames check because of all the new code moved into this function
now.

[dogben, 2016/05/19 14:27:22]

I don't understand.

[rmistry, 2016/05/19 14:42:19]

Done.

+	// Batcharchive the tasks.
+	tasksToHashes, err := s.BatchArchiveTargets(genJSONs, BATCHARCHIVE_TIMEOUT)
+	if err != nil {
+		return fmt.Errorf("Could not batch archive targets: %s", err)
+	}
+	if len(taskNames) != len(tasksToHashes) {
+		return fmt.Errorf("len(taskNames) was %d and len(tasksToHashes) was %d", len(taskNames), len(tasksToHashes))
+	}
+	// Trigger swarming using the isolate hashes.
+	dimensions := map[string]string{"pool": SWARMING_POOL}
+	tasks, err := s.TriggerSwarmingTasks(tasksToHashes, dimensions, swarming.RECOMMENDED_PRIORITY, swarming.RECOMMENDED_EXPIRATION, hardTimeout, ioTimeout, false)
+	if err != nil {
+		return fmt.Errorf("Could not trigger swarming task: %s", err)
+	}
+	// Collect all tasks and log the ones that fail.
+	for _, task := range tasks {
+		if _, _, err := task.Collect(s); err != nil {
+			glog.Errorf("task %s failed: %s", task.Title, err)
+			continue
+		}
+	}
+	return nil
+}
+
+// GetPathToPyFiles returns the location of CT's python scripts.
+func GetPathToPyFiles(runOnSwarming bool) string {
+	var pathToPyFiles string

[dogben, 2016/05/18 17:38:26]

nit: just return rather than assigning to pathToPyFiles?

[rmistry, 2016/05/19 12:59:50]

Done.

+	if runOnSwarming {
+		pathToPyFiles = filepath.Join(filepath.Dir(filepath.Dir(os.Args[0])), "src", "go.skia.org", "infra", "ct", "py")
+	} else {
+		_, currentFile, _, _ := runtime.Caller(0)
+		pathToPyFiles = filepath.Join(filepath.Dir(filepath.Dir(filepath.Dir(currentFile))), "py")
+	}
+	return pathToPyFiles
+}