Change PodWorkers to have desired cache.

pkg/kubelet/dockertools/docker_cache.go

@@ -23,6 +23,7 @@ import (
 
 type DockerCache interface {
 	RunningContainers() (DockerContainers, error)
+	ForceUpdateIfOlder(time.Time) error
 }
 
 func NewDockerCache(client DockerInterface) (DockerCache, error) {
@@ -49,6 +50,9 @@ type dockerCache struct {
 	updatingThreadStopTime time.Time
 }
 
+// Ensure that dockerCache abides by the DockerCache interface.
+var _ DockerCache = new(dockerCache)
+
 func (d *dockerCache) RunningContainers() (DockerContainers, error) {
 	d.lock.Lock()
 	defer d.lock.Unlock()
@@ -69,6 +73,20 @@ func (d *dockerCache) RunningContainers() (DockerContainers, error) {
 	return d.containers, nil
 }
 
+func (d *dockerCache) ForceUpdateIfOlder(minExpectedCacheTime time.Time) error {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+	if d.cacheTime.Before(minExpectedCacheTime) {
+		containers, err := GetKubeletDockerContainers(d.client, false)
+		if err != nil {
+			return err
+		}
+		d.containers = containers
+		d.cacheTime = time.Now()
+	}
+	return nil
+}
+
 func (d *dockerCache) startUpdatingCache() {
 	run := true
 	for run {

pkg/kubelet/dockertools/fake_docker_client.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"reflect"
 	"sync"
+	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/fsouza/go-dockerclient"
@@ -246,3 +247,7 @@ func NewFakeDockerCache(client DockerInterface) DockerCache {
 func (f *FakeDockerCache) RunningContainers() (DockerContainers, error) {
 	return GetKubeletDockerContainers(f.client, false)
 }
+
+func (f *FakeDockerCache) ForceUpdateIfOlder(time.Time) error {
+	return nil
+}