fleetd:registry: improve Units() performance remove extra loops when fetching Jobs list from etcd

functional/unit_action_test.go

@@ -15,8 +15,11 @@
 package functional
 
 import (
+	"fmt"
 	"io/ioutil"
 	"path"
+	"reflect"
+	"sort"
 	"strings"
 	"testing"
 
@@ -404,3 +407,63 @@ func TestUnitStatus(t *testing.T) {
 			stdout, stderr)
 	}
 }
+
+// TestListUnitFilesOrder simply checks if "fleetctl list-unit-files" returns
+// an ordered list of units
+func TestListUnitFilesOrder(t *testing.T) {
+	cluster, err := platform.NewNspawnCluster("smoke")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cluster.Destroy()
+
+	m, err := cluster.CreateMember()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = cluster.WaitForNMachines(m, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Combine units
+	var units []string
+	for i := 1; i <= 20; i++ {
+		unit := fmt.Sprintf("fixtures/units/hello@%02d.service", i)
+		stdout, stderr, err := cluster.Fleetctl(m, "submit", unit)
+		if err != nil {
+			t.Fatalf("Failed to submit a batch of units: \nstdout: %s\nstder: %s\nerr: %v", stdout, stderr, err)
+		}
+		units = append(units, unit)
+	}
+
+	// make sure that all unit files will show up
+	_, err = cluster.WaitForNUnitFiles(m, 20)
+	if err != nil {
+		t.Fatal("Failed to run list-unit-files: %v", err)
+	}
+
+	stdout, _, err := cluster.Fleetctl(m, "list-unit-files", "--no-legend", "--fields", "unit")
+	if err != nil {
+		t.Fatal("Failed to run list-unit-files: %v", err)
+	}
+
+	outUnits := strings.Split(strings.TrimSpace(stdout), "\n")
+
+	var sortable sort.StringSlice
+	for _, name := range units {
+		n := path.Base(name)
+		sortable = append(sortable, n)
+	}
+	sortable.Sort()
+
+	var inUnits []string
+	for _, name := range sortable {
+		inUnits = append(inUnits, name)
+	}
+
+	if !reflect.DeepEqual(inUnits, outUnits) {
+		t.Fatalf("Failed to get a sorted list of units from list-unit-files")
+	}
+}

registry/job.go

@@ -90,6 +90,7 @@ func (r *EtcdRegistry) Schedule() ([]job.ScheduledUnit, error) {
 func (r *EtcdRegistry) Units() ([]job.Unit, error) {
 	key := r.prefixed(jobPrefix)
 	opts := &etcd.GetOptions{
+		// We need Job Units to be sorted
 		Sort:      true,
 		Recursive: true,
 	}
@@ -117,7 +118,7 @@ func (r *EtcdRegistry) Units() ([]job.Unit, error) {
 		return unit
 	}
 
-	uMap := make(map[string]*job.Unit)
+	units := make([]job.Unit, 0)
 	for _, dir := range res.Node.Nodes {
 		u, err := r.dirToUnit(dir, unitHashLookupFunc)
 		if err != nil {
@@ -127,18 +128,8 @@ func (r *EtcdRegistry) Units() ([]job.Unit, error) {
 		if u == nil {
 			continue
 		}
-		uMap[u.Name] = u
-	}
-
-	var sortable sort.StringSlice
-	for name, _ := range uMap {
-		sortable = append(sortable, name)
-	}
-	sortable.Sort()
 
-	units := make([]job.Unit, 0, len(sortable))
-	for _, name := range sortable {
-		units = append(units, *uMap[name])
+		units = append(units, *u)
 	}
 
 	return units, nil