Fixed a leaked go routine by adding a Close() function.

cache.go

@@ -7,9 +7,10 @@ import (
 
 // Cache is a synchronised map of items that auto-expire once stale
 type Cache struct {
-	mutex sync.RWMutex
-	ttl   time.Duration
-	items map[string]*Item
+	mutex    sync.RWMutex
+	ttl      time.Duration
+	items    map[string]*Item
+	shutdown chan bool
 }
 
 // Set is a thread-safe way to add new items to the map
@@ -47,6 +48,10 @@ func (cache *Cache) Count() int {
 	return count
 }
 
+func (cache *Cache) Close() {
+	cache.shutdown <- true
+}
+
 func (cache *Cache) cleanup() {
 	cache.mutex.Lock()
 	for key, item := range cache.items {
@@ -66,6 +71,8 @@ func (cache *Cache) startCleanupTimer() {
 	go (func() {
 		for {
 			select {
+			case <-cache.shutdown:
+				return
 			case <-ticker:
 				cache.cleanup()
 			}
@@ -76,8 +83,9 @@ func (cache *Cache) startCleanupTimer() {
 // NewCache is a helper to create instance of the Cache struct
 func NewCache(duration time.Duration) *Cache {
 	cache := &Cache{
-		ttl:   duration,
-		items: map[string]*Item{},
+		ttl:      duration,
+		items:    map[string]*Item{},
+		shutdown: make(chan bool, 1),
 	}
 	cache.startCleanupTimer()
 	return cache

cache_test.go

@@ -1,14 +1,16 @@
 package ttlcache
 
 import (
+	"runtime"
 	"testing"
 	"time"
 )
 
 func TestGet(t *testing.T) {
 	cache := &Cache{
-		ttl:   time.Second,
-		items: map[string]*Item{},
+		ttl:      time.Second,
+		items:    map[string]*Item{},
+		shutdown: make(chan bool, 1),
 	}
 
 	data, exists := cache.Get("hello")
@@ -24,12 +26,15 @@ func TestGet(t *testing.T) {
 	if data != "world" {
 		t.Errorf("Expected cache to return `world` for `hello`")
 	}
+
+	cache.Close()
 }
 
 func TestExpiration(t *testing.T) {
 	cache := &Cache{
-		ttl:   time.Second,
-		items: map[string]*Item{},
+		ttl:      time.Second,
+		items:    map[string]*Item{},
+		shutdown: make(chan bool, 1),
 	}
 
 	cache.Set("x", "1")
@@ -84,4 +89,20 @@ func TestExpiration(t *testing.T) {
 	if count != 0 {
 		t.Errorf("Expected cache to be empty")
 	}
+
+	cache.Close()
+}
+
+func TestClose(t *testing.T) {
+	initial := runtime.NumGoroutine()
+	cache := NewCache(time.Second)
+	if runtime.NumGoroutine() != 1+initial {
+		t.Errorf("Expected the number of go routines to increase by one")
+	}
+
+	cache.Close()
+	time.Sleep(time.Second)
+	if runtime.NumGoroutine() != initial {
+		t.Errorf("Expected the number of go routines to decrease by one")
+	}
 }