A cache should not require string keys

cache.go

@@ -33,23 +33,23 @@ const (
 	DefaultExpiration time.Duration = 0
 )
 
-type Cache[T any] struct {
-	*cache[T]
+type Cache[K comparable,T any] struct {
+	*cache[K, T]
 	// If this is confusing, see the comment at the bottom of New()
 }
+type cache[K comparable, T any] struct {
 
-type cache[T any] struct {
 	defaultExpiration time.Duration
-	items             map[string]Item[T]
+	items             map[K]Item[T]
 	mu                sync.RWMutex
-	onEvicted         func(string, T)
-	janitor           *janitor[T]
+	onEvicted         func(K, T)
+	janitor           *janitor[K, T]
 }
 
 // Add an item to the cache, replacing any existing item. If the duration is 0
 // (DefaultExpiration), the cache's default expiration time is used. If it is -1
 // (NoExpiration), the item never expires.
-func (c *cache[T]) Set(k string, x T, d time.Duration) {
+func (c *cache[K, T]) Set(k K, x T, d time.Duration) {
 	// "Inlining" of set
 	var e int64
 	if d == DefaultExpiration {
@@ -68,7 +68,7 @@ func (c *cache[T]) Set(k string, x T, d time.Duration) {
 	c.mu.Unlock()
 }
 
-func (c *cache[T]) set(k string, x T, d time.Duration) {
+func (c *cache[K, T]) set(k K, x T, d time.Duration) {
 	var e int64
 	if d == DefaultExpiration {
 		d = c.defaultExpiration
@@ -84,18 +84,18 @@ func (c *cache[T]) set(k string, x T, d time.Duration) {
 
 // Add an item to the cache, replacing any existing item, using the default
 // expiration.
-func (c *cache[T]) SetDefault(k string, x T) {
+func (c *cache[K, T]) SetDefault(k K, x T) {
 	c.Set(k, x, DefaultExpiration)
 }
 
 // Add an item to the cache only if an item doesn't already exist for the given
 // key, or if the existing item has expired. Returns an error otherwise.
-func (c *cache[T]) Add(k string, x T, d time.Duration) error {
+func (c *cache[K, T]) Add(k K, x T, d time.Duration) error {
 	c.mu.Lock()
 	_, found := c.get(k)
 	if found {
 		c.mu.Unlock()
-		return fmt.Errorf("Item %s already exists", k)
+		return fmt.Errorf("Item %s already exists", "key")
 	}
 	c.set(k, x, d)
 	c.mu.Unlock()
@@ -104,12 +104,12 @@ func (c *cache[T]) Add(k string, x T, d time.Duration) error {
 
 // Set a new value for the cache key only if it already exists, and the existing
 // item hasn't expired. Returns an error otherwise.
-func (c *cache[T]) Replace(k string, x T, d time.Duration) error {
+func (c *cache[K, T]) Replace(k K, x T, d time.Duration) error {
 	c.mu.Lock()
 	_, found := c.get(k)
 	if !found {
 		c.mu.Unlock()
-		return fmt.Errorf("Item %s doesn't exist", k)
+		return fmt.Errorf("Item %s doesn't exist", "key")
 	}
 	c.set(k, x, d)
 	c.mu.Unlock()
@@ -118,7 +118,7 @@ func (c *cache[T]) Replace(k string, x T, d time.Duration) error {
 
 // Get an item from the cache. Returns the item or nil, and a bool indicating
 // whether the key was found.
-func (c *cache[T]) Get(k string) (T, bool) {
+func (c *cache[K, T]) Get(k K) (T, bool) {
 	c.mu.RLock()
 	// "Inlining" of get and Expired
 	item, found := c.items[k]
@@ -140,7 +140,7 @@ func (c *cache[T]) Get(k string) (T, bool) {
 // It returns the item or nil, the expiration time if one is set (if the item
 // never expires a zero value for time.Time is returned), and a bool indicating
 // whether the key was found.
-func (c *cache[T]) GetWithExpiration(k string) (T, time.Time, bool) {
+func (c *cache[K, T]) GetWithExpiration(k K) (T, time.Time, bool) {
 	c.mu.RLock()
 	// "Inlining" of get and Expired
 	item, found := c.items[k]
@@ -166,7 +166,7 @@ func (c *cache[T]) GetWithExpiration(k string) (T, time.Time, bool) {
 	return item.Object, time.Time{}, true
 }
 
-func (c *cache[T]) get(k string) (T, bool) {
+func (c *cache[K, T]) get(k K) (T, bool) {
 	item, found := c.items[k]
 	if !found {
 		return *new(T), false
@@ -181,7 +181,7 @@ func (c *cache[T]) get(k string) (T, bool) {
 }
 
 // Delete an item from the cache. Does nothing if the key is not in the cache.
-func (c *cache[T]) Delete(k string) {
+func (c *cache[K, T]) Delete(k K) {
 	c.mu.Lock()
 	v, evicted := c.delete(k)
 	c.mu.Unlock()
@@ -190,7 +190,7 @@ func (c *cache[T]) Delete(k string) {
 	}
 }
 
-func (c *cache[T]) delete(k string) (T, bool) {
+func (c *cache[K, T]) delete(k K) (T, bool) {
 	if c.onEvicted != nil {
 		if v, found := c.items[k]; found {
 			delete(c.items, k)
@@ -201,14 +201,14 @@ func (c *cache[T]) delete(k string) (T, bool) {
 	return *new(T), false
 }
 
-type keyAndValue[T any] struct {
-	key   string
+type keyAndValue[K comparable, T any] struct {
+	key   K
 	value T
 }
 
 // Delete all expired items from the cache.
-func (c *cache[T]) DeleteExpired() {
-	var evictedItems []keyAndValue[T]
+func (c *cache[K, T]) DeleteExpired() {
+	var evictedItems []keyAndValue[K, T]
 	now := time.Now().UnixNano()
 	c.mu.Lock()
 	for k, v := range c.items {
@@ -216,7 +216,7 @@ func (c *cache[T]) DeleteExpired() {
 		if v.Expiration > 0 && now > v.Expiration {
 			ov, evicted := c.delete(k)
 			if evicted {
-				evictedItems = append(evictedItems, keyAndValue[T]{k, ov})
+				evictedItems = append(evictedItems, keyAndValue[K, T]{k, ov})
 			}
 		}
 	}
@@ -229,7 +229,7 @@ func (c *cache[T]) DeleteExpired() {
 // Sets an (optional) function that is called with the key and value when an
 // item is evicted from the cache. (Including when it is deleted manually, but
 // not when it is overwritten.) Set to nil to disable.
-func (c *cache[T]) OnEvicted(f func(string, T)) {
+func (c *cache[K, T]) OnEvicted(f func(K, T)) {
 	c.mu.Lock()
 	c.onEvicted = f
 	c.mu.Unlock()
@@ -239,7 +239,7 @@ func (c *cache[T]) OnEvicted(f func(string, T)) {
 //
 // NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
 // documentation for NewFrom().)
-func (c *cache[T]) Save(w io.Writer) (err error) {
+func (c *cache[K, T]) Save(w io.Writer) (err error) {
 	enc := gob.NewEncoder(w)
 	c.mu.RLock()
 	defer c.mu.RUnlock()
@@ -264,7 +264,7 @@ func (c *cache[T]) Save(w io.Writer) (err error) {
 //
 // NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
 // documentation for NewFrom().)
-func (c *cache[T]) SaveFile(fname string) error {
+func (c *cache[K, T]) SaveFile(fname string) error {
 	fp, err := os.Create(fname)
 	if err != nil {
 		return err
@@ -282,9 +282,9 @@ func (c *cache[T]) SaveFile(fname string) error {
 //
 // NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
 // documentation for NewFrom().)
-func (c *cache[T]) Load(r io.Reader) error {
+func (c *cache[K, T]) Load(r io.Reader) error {
 	dec := gob.NewDecoder(r)
-	items := map[string]Item[T]{}
+	items := map[K]Item[T]{}
 	err := dec.Decode(&items)
 	if err == nil {
 		c.mu.Lock()
@@ -304,7 +304,7 @@ func (c *cache[T]) Load(r io.Reader) error {
 //
 // NOTE: This method is deprecated in favor of c.Items() and NewFrom() (see the
 // documentation for NewFrom().)
-func (c *cache[T]) LoadFile(fname string) error {
+func (c *cache[K, T]) LoadFile(fname string) error {
 	fp, err := os.Open(fname)
 	if err != nil {
 		return err
@@ -318,10 +318,10 @@ func (c *cache[T]) LoadFile(fname string) error {
 }
 
 // Copies all unexpired items in the cache into a new map and returns it.
-func (c *cache[T]) Items() map[string]Item[T] {
+func (c *cache[K, T]) Items() map[K]Item[T] {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
-	m := make(map[string]Item[T], len(c.items))
+	m := make(map[K]Item[T], len(c.items))
 	now := time.Now().UnixNano()
 	for k, v := range c.items {
 		// "Inlining" of Expired
@@ -337,7 +337,7 @@ func (c *cache[T]) Items() map[string]Item[T] {
 
 // Returns the number of items in the cache. This may include items that have
 // expired, but have not yet been cleaned up.
-func (c *cache[T]) ItemCount() int {
+func (c *cache[K, T]) ItemCount() int {
 	c.mu.RLock()
 	n := len(c.items)
 	c.mu.RUnlock()
@@ -345,18 +345,18 @@ func (c *cache[T]) ItemCount() int {
 }
 
 // Delete all items from the cache.
-func (c *cache[T]) Flush() {
+func (c *cache[K, T]) Flush() {
 	c.mu.Lock()
-	c.items = map[string]Item[T]{}
+	c.items = map[K]Item[T]{}
 	c.mu.Unlock()
 }
 
-type janitor[T any] struct {
+type janitor[K comparable, T any] struct {
 	Interval time.Duration
 	stop     chan bool
 }
 
-func (j *janitor[T]) Run(c *cache[T]) {
+func (j *janitor[K, T]) Run(c *cache[K, T]) {
 	ticker := time.NewTicker(j.Interval)
 	for {
 		select {
@@ -369,12 +369,12 @@ func (j *janitor[T]) Run(c *cache[T]) {
 	}
 }
 
-func stopJanitor[T any](c *Cache[T]) {
+func stopJanitor[K comparable, T any](c *Cache[K, T]) {
 	c.janitor.stop <- true
 }
 
-func runJanitor[T any](c *cache[T], ci time.Duration) {
-	j := &janitor[T]{
+func runJanitor[K comparable, T any](c *cache[K, T], ci time.Duration) {
+	j := &janitor[K, T]{
 		Interval: ci,
 		stop:     make(chan bool),
 	}
@@ -382,28 +382,28 @@ func runJanitor[T any](c *cache[T], ci time.Duration) {
 	go j.Run(c)
 }
 
-func newCache[T any](de time.Duration, m map[string]Item[T]) *cache[T] {
+func newCache[K comparable, T any](de time.Duration, m map[K]Item[T]) *cache[K, T] {
 	if de == 0 {
 		de = -1
 	}
-	c := &cache[T]{
+	c := &cache[K, T]{
 		defaultExpiration: de,
 		items:             m,
 	}
 	return c
 }
 
-func newCacheWithJanitor[T any](de time.Duration, ci time.Duration, m map[string]Item[T]) *Cache[T] {
-	c := newCache[T](de, m)
+func newCacheWithJanitor[K comparable, T any](de time.Duration, ci time.Duration, m map[K]Item[T]) *Cache[K, T] {
+	c := newCache[K, T](de, m)
 	// This trick ensures that the janitor goroutine (which--granted it
 	// was enabled--is running DeleteExpired on c forever) does not keep
 	// the returned C object from being garbage collected. When it is
 	// garbage collected, the finalizer stops the janitor goroutine, after
 	// which c can be collected.
-	C := &Cache[T]{c}
+	C := &Cache[K, T]{c}
 	if ci > 0 {
 		runJanitor(c, ci)
-		runtime.SetFinalizer(C, stopJanitor[T])
+		runtime.SetFinalizer(C, stopJanitor[K, T])
 	}
 	return C
 }
@@ -413,9 +413,9 @@ func newCacheWithJanitor[T any](de time.Duration, ci time.Duration, m map[string
 // the items in the cache never expire (by default), and must be deleted
 // manually. If the cleanup interval is less than one, expired items are not
 // deleted from the cache before calling c.DeleteExpired().
-func New[T any](defaultExpiration, cleanupInterval time.Duration) *Cache[T] {
-	items := make(map[string]Item[T])
-	return newCacheWithJanitor[T](defaultExpiration, cleanupInterval, items)
+func New[K comparable, T any](defaultExpiration, cleanupInterval time.Duration) *Cache[K, T] {
+	items := make(map[K]Item[T])
+	return newCacheWithJanitor[K, T](defaultExpiration, cleanupInterval, items)
 }
 
 // Return a new cache with a given default expiration duration and cleanup
@@ -439,6 +439,6 @@ func New[T any](defaultExpiration, cleanupInterval time.Duration) *Cache[T] {
 // gob.Register() the individual types stored in the cache before encoding a
 // map retrieved with c.Items(), and to register those same types before
 // decoding a blob containing an items map.
-func NewFrom[T any](defaultExpiration, cleanupInterval time.Duration, items map[string]Item[T]) *Cache[T] {
+func NewFrom[K comparable, T any](defaultExpiration, cleanupInterval time.Duration, items map[K]Item[T]) *Cache[K, T] {
 	return newCacheWithJanitor(defaultExpiration, cleanupInterval, items)
 }

cache_test.go

@@ -23,7 +23,7 @@ func NewTestStruct(num int) TestStruct {
 }
 
 func TestCache(t *testing.T) {
-	tc := New[TestStruct](DefaultExpiration, 0)
+	tc := New[string, TestStruct](DefaultExpiration, 0)
 
 	a, found := tc.Get("a")
 	if found {
@@ -57,7 +57,7 @@ func TestCache(t *testing.T) {
 func TestCacheTimes(t *testing.T) {
 	var found bool
 
-	tc := New[TestStruct](50*time.Millisecond, 1*time.Millisecond)
+	tc := New[string, TestStruct](50*time.Millisecond, 1*time.Millisecond)
 	tc.Set("a", NewTestStruct(1), DefaultExpiration)
 	tc.Set("b", NewTestStruct(2), NoExpiration)
 	tc.Set("c", NewTestStruct(3), 20*time.Millisecond)
@@ -122,7 +122,7 @@ func TestNewFrom(t *testing.T) {
 }
 
 func TestStorePointerToStruct(t *testing.T) {
-	tc := New[*TestStruct](DefaultExpiration, 0)
+	tc := New[string, *TestStruct](DefaultExpiration, 0)
 	tc.Set("foo", &TestStruct{Num: 1}, DefaultExpiration)
 	x, found := tc.Get("foo")
 	if !found {
@@ -142,7 +142,7 @@ func TestStorePointerToStruct(t *testing.T) {
 }
 
 func TestAdd(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	err := tc.Add("foo", "bar", DefaultExpiration)
 	if err != nil {
 		t.Error("Couldn't add foo even though it shouldn't exist")
@@ -154,7 +154,7 @@ func TestAdd(t *testing.T) {
 }
 
 func TestReplace(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	err := tc.Replace("foo", "bar", DefaultExpiration)
 	if err == nil {
 		t.Error("Replaced foo when it shouldn't exist")
@@ -167,7 +167,7 @@ func TestReplace(t *testing.T) {
 }
 
 func TestDelete(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	tc.Set("foo", "bar", DefaultExpiration)
 	tc.Delete("foo")
 	_, found := tc.Get("foo")
@@ -177,7 +177,7 @@ func TestDelete(t *testing.T) {
 }
 
 func TestItemCount(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	tc.Set("foo", "1", DefaultExpiration)
 	tc.Set("bar", "2", DefaultExpiration)
 	tc.Set("baz", "3", DefaultExpiration)
@@ -187,7 +187,7 @@ func TestItemCount(t *testing.T) {
 }
 
 func TestFlush(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	tc.Set("foo", "bar", DefaultExpiration)
 	tc.Set("baz", "yes", DefaultExpiration)
 	tc.Flush()
@@ -203,7 +203,7 @@ func TestFlush(t *testing.T) {
 }
 
 func TestOnEvicted(t *testing.T) {
-	tc := New[int](DefaultExpiration, 0)
+	tc := New[string, int](DefaultExpiration, 0)
 	tc.Set("foo", 3, DefaultExpiration)
 	if tc.onEvicted != nil {
 		t.Fatal("tc.onEvicted is not nil")
@@ -226,7 +226,7 @@ func TestOnEvicted(t *testing.T) {
 }
 
 func TestCacheSerialization(t *testing.T) {
-	tc := New[TestStruct](DefaultExpiration, 0)
+	tc := New[string, TestStruct](DefaultExpiration, 0)
 	testFillAndSerialize(t, tc)
 
 	// Check if gob.Register behaves properly even after multiple gob.Register
@@ -234,7 +234,7 @@ func TestCacheSerialization(t *testing.T) {
 	testFillAndSerialize(t, tc)
 }
 
-func testFillAndSerialize(t *testing.T, tc *Cache[TestStruct]) {
+func testFillAndSerialize(t *testing.T, tc *Cache[string, TestStruct]) {
 
 	tc.Set("*struct", TestStruct{Num: 1}, DefaultExpiration)
 
@@ -260,7 +260,7 @@ func testFillAndSerialize(t *testing.T, tc *Cache[TestStruct]) {
 		t.Fatal("Couldn't save cache to fp:", err)
 	}
 
-	oc := New[TestStruct](DefaultExpiration, 0)
+	oc := New[string, TestStruct](DefaultExpiration, 0)
 	err = oc.Load(fp)
 	if err != nil {
 		t.Fatal("Couldn't load cache from fp:", err)
@@ -297,7 +297,7 @@ func testFillAndSerialize(t *testing.T, tc *Cache[TestStruct]) {
 }
 
 func TestFileSerialization(t *testing.T) {
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	tc.Add("a", "a", DefaultExpiration)
 	tc.Add("b", "b", DefaultExpiration)
 	f, err := ioutil.TempFile("", "go-cache-cache.dat")
@@ -308,7 +308,7 @@ func TestFileSerialization(t *testing.T) {
 	f.Close()
 	tc.SaveFile(fname)
 
-	oc := New[string](DefaultExpiration, 0)
+	oc := New[string, string](DefaultExpiration, 0)
 	oc.Add("a", "aa", 0) // this should not be overwritten
 	err = oc.LoadFile(fname)
 	if err != nil {
@@ -336,7 +336,7 @@ func TestFileSerialization(t *testing.T) {
 }
 
 func TestSerializeUnserializable(t *testing.T) {
-	tc := New[chan bool](DefaultExpiration, 0)
+	tc := New[string, chan bool](DefaultExpiration, 0)
 	ch := make(chan bool, 1)
 	ch <- true
 	tc.Set("chan", ch, DefaultExpiration)
@@ -357,7 +357,7 @@ func BenchmarkCacheGetStringNotExpiring(b *testing.B) {
 
 func benchmarkCacheGetString(b *testing.B, exp time.Duration) {
 	b.StopTimer()
-	tc := New[string](exp, 0)
+	tc := New[string, string](exp, 0)
 	tc.Set("foo", "bar", DefaultExpiration)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
@@ -418,7 +418,7 @@ func BenchmarkCacheGetConcurrentNotExpiring(b *testing.B) {
 
 func benchmarkCacheGetConcurrent(b *testing.B, exp time.Duration) {
 	b.StopTimer()
-	tc := New[string](exp, 0)
+	tc := New[string, string](exp, 0)
 	tc.Set("foo", "bar", DefaultExpiration)
 	wg := new(sync.WaitGroup)
 	workers := runtime.NumCPU()
@@ -474,7 +474,7 @@ func benchmarkCacheGetManyConcurrent(b *testing.B, exp time.Duration) {
 	// in sharded_test.go.
 	b.StopTimer()
 	n := 10000
-	tc := New[string](exp, 0)
+	tc := New[string, string](exp, 0)
 	keys := make([]string, n)
 	for i := 0; i < n; i++ {
 		k := "foo" + strconv.Itoa(i)
@@ -506,7 +506,7 @@ func BenchmarkCacheSetStringNotExpiring(b *testing.B) {
 
 func benchmarkCacheSetString(b *testing.B, exp time.Duration) {
 	b.StopTimer()
-	tc := New[string](exp, 0)
+	tc := New[string, string](exp, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Set("foo", "bar", DefaultExpiration)
@@ -527,7 +527,7 @@ func BenchmarkRWMutexMapSet(b *testing.B) {
 
 func BenchmarkCacheSetDelete(b *testing.B) {
 	b.StopTimer()
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Set("foo", "bar", DefaultExpiration)
@@ -552,7 +552,7 @@ func BenchmarkRWMutexMapSetDelete(b *testing.B) {
 
 func BenchmarkCacheSetDeleteSingleLock(b *testing.B) {
 	b.StopTimer()
-	tc := New[string](DefaultExpiration, 0)
+	tc := New[string, string](DefaultExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.mu.Lock()
@@ -577,7 +577,7 @@ func BenchmarkRWMutexMapSetDeleteSingleLock(b *testing.B) {
 
 func BenchmarkDeleteExpiredLoop(b *testing.B) {
 	b.StopTimer()
-	tc := New[string](5*time.Minute, 0)
+	tc := New[string, string](5*time.Minute, 0)
 	tc.mu.Lock()
 	for i := 0; i < 100000; i++ {
 		tc.set(strconv.Itoa(i), "bar", DefaultExpiration)
@@ -590,7 +590,7 @@ func BenchmarkDeleteExpiredLoop(b *testing.B) {
 }
 
 func TestGetWithExpiration(t *testing.T) {
-	tc := New[int](DefaultExpiration, 0)
+	tc := New[string, int](DefaultExpiration, 0)
 
 	a, expiration, found := tc.GetWithExpiration("a")
 	if found || !expiration.IsZero() {
@@ -652,7 +652,7 @@ func BenchmarkCacheGetStructNotExpiring(b *testing.B) {
 
 func benchmarkCacheGetStruct(b *testing.B, exp time.Duration) {
 	b.StopTimer()
-	tc := New[*TestStruct](exp, 0)
+	tc := New[string, *TestStruct](exp, 0)
 
 	tc.Set("foo", &TestStruct{Num: 1}, DefaultExpiration)
 	b.StartTimer()
@@ -673,7 +673,7 @@ func BenchmarkCacheSetStructNotExpiring(b *testing.B) {
 
 func benchmarkCacheSetStruct(b *testing.B, exp time.Duration) {
 	b.StopTimer()
-	tc := New[*TestStruct](exp, 0)
+	tc := New[string, *TestStruct](exp, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Set("foo", &TestStruct{Num: 1}, DefaultExpiration)
@@ -682,7 +682,7 @@ func benchmarkCacheSetStruct(b *testing.B, exp time.Duration) {
 
 func BenchmarkCacheSetFatStructExpiring(b *testing.B) {
 	b.StopTimer()
-	tc := New[*TestStruct](NoExpiration, 0)
+	tc := New[string, *TestStruct](NoExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Set("foo", &TestStruct{Num: 1, Children: []*TestStruct{
@@ -692,7 +692,7 @@ func BenchmarkCacheSetFatStructExpiring(b *testing.B) {
 
 func BenchmarkCacheGetFatStructNotExpiring(b *testing.B) {
 	b.StopTimer()
-	tc := New[*TestStruct](NoExpiration, 0)
+	tc := New[string, *TestStruct](NoExpiration, 0)
 
 	tc.Set("foo", &TestStruct{Num: 1, Children: []*TestStruct{
 		&TestStruct{Num: 2, Children: []*TestStruct{}}}}, DefaultExpiration)