probe/kubernetes: Speed up lookups of large lists of cronjobs and jobs

Currently joining the two lists is O(mn), by putting into a hashmap first it's O(m+n)

probe/kubernetes/client.go

@@ -11,6 +11,7 @@ import (
 	log "github.com/Sirupsen/logrus"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes"
 	apiv1 "k8s.io/client-go/pkg/api/v1"
 	apiappsv1beta1 "k8s.io/client-go/pkg/apis/apps/v1beta1"
@@ -301,10 +302,11 @@ func (c *client) WalkCronJobs(f func(CronJob) error) error {
 	if c.cronJobStore == nil {
 		return nil
 	}
-	jobs := []*apibatchv1.Job{}
+	// We index jobs by id to make lookup for each cronjob more efficient
+	jobs := map[types.UID]*apibatchv1.Job{}
 	for _, m := range c.jobStore.List() {
 		j := m.(*apibatchv1.Job)
-		jobs = append(jobs, j)
+		jobs[j.UID] = j
 	}
 	for _, m := range c.cronJobStore.List() {
 		cj := m.(*apibatchv2alpha1.CronJob)

probe/kubernetes/cronjob.go

@@ -6,6 +6,7 @@ import (
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/types"
 	batchv1 "k8s.io/client-go/pkg/apis/batch/v1"
 	batchv2alpha1 "k8s.io/client-go/pkg/apis/batch/v2alpha1"
 
@@ -35,14 +36,11 @@ type cronJob struct {
 
 // NewCronJob creates a new cron job. jobs should be all jobs, which will be filtered
 // for those matching this cron job.
-func NewCronJob(cj *batchv2alpha1.CronJob, jobs []*batchv1.Job) CronJob {
+func NewCronJob(cj *batchv2alpha1.CronJob, jobs map[types.UID]*batchv1.Job) CronJob {
 	myJobs := []*batchv1.Job{}
-	for _, j := range jobs {
-		for _, o := range cj.Status.Active {
-			if j.UID == o.UID {
-				myJobs = append(myJobs, j)
-				break
-			}
+	for _, o := range cj.Status.Active {
+		if j, ok := jobs[o.UID]; ok {
+			myJobs = append(myJobs, j)
 		}
 	}
 	return &cronJob{