genericize ip cache

pkg/master/ip_cache.go

@@ -17,7 +17,6 @@ limitations under the License.
 package master
 
 import (
-	"sync"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/cloudprovider"
@@ -26,19 +25,6 @@ import (
 	"github.com/golang/glog"
 )
 
-type ipCacheEntry struct {
-	ip         string
-	lastUpdate time.Time
-}
-
-type ipCache struct {
-	clock         util.Clock
-	cloudProvider cloudprovider.Interface
-	cache         map[string]ipCacheEntry
-	lock          sync.Mutex
-	ttl           time.Duration
-}
-
 // NewIPCache makes a new ip caching layer, which will get IP addresses from cp,
 // and use clock for deciding when to re-get an IP address.
 // Thread-safe.
@@ -47,30 +33,24 @@ type ipCache struct {
 // that could be produced from a template and a type via `go generate`.
 func NewIPCache(cp cloudprovider.Interface, clock util.Clock, ttl time.Duration) *ipCache {
 	return &ipCache{
-		clock:         clock,
-		cloudProvider: cp,
-		cache:         map[string]ipCacheEntry{},
-		ttl:           ttl,
+		cache: util.NewTimeCache(
+			clock,
+			ttl,
+			func(host string) util.T {
+				return getInstanceIPFromCloud(cp, host)
+			},
+		),
 	}
 }
 
+type ipCache struct {
+	cache util.TimeCache
+}
+
 // GetInstanceIP returns the IP address of host, from the cache
 // if possible, otherwise it asks the cloud provider.
 func (c *ipCache) GetInstanceIP(host string) string {
-	c.lock.Lock()
-	defer c.lock.Unlock()
-	data, ok := c.cache[host]
-	now := c.clock.Now()
-
-	if !ok || now.Sub(data.lastUpdate) > c.ttl {
-		ip := getInstanceIPFromCloud(c.cloudProvider, host)
-		data = ipCacheEntry{
-			ip:         ip,
-			lastUpdate: now,
-		}
-		c.cache[host] = data
-	}
-	return data.ip
+	return c.cache.Get(host).(string)
 }
 
 func getInstanceIPFromCloud(cloud cloudprovider.Interface, host string) string {