Code review (round 1)

util/lookup_cache.go

@@ -10,14 +10,14 @@ import (
 //
 // Example:
 //
-//	    lookup := func() (string, error) {
-//		   r, _ := http.Get("...")
-//		   s, _ := io.ReadAll(r.Body)
-//		   return string(s), nil
-//		}
-//		c := NewLookupCache[string](lookup, time.Hour)
-//		fmt.Println(c.Get()) // Fetches the string via HTTP
-//		fmt.Println(c.Get()) // Uses cached value
+//	lookup := func() (string, error) {
+//	   r, _ := http.Get("...")
+//	   s, _ := io.ReadAll(r.Body)
+//	   return string(s), nil
+//	}
+//	c := NewLookupCache[string](lookup, time.Hour)
+//	fmt.Println(c.Get()) // Fetches the string via HTTP
+//	fmt.Println(c.Get()) // Uses cached value
 type LookupCache[T any] struct {
 	value   *T
 	lookup  func() (T, error)
@@ -26,8 +26,12 @@ type LookupCache[T any] struct {
 	mu      sync.Mutex
 }
 
+// LookupFunc is a function that is called by the LookupCache if the underlying
+// value is out-of-date. It returns the new value, or an error.
+type LookupFunc[T any] func() (T, error)
+
 // NewLookupCache creates a new LookupCache with a given time-to-live (TTL)
-func NewLookupCache[T any](lookup func() (T, error), ttl time.Duration) *LookupCache[T] {
+func NewLookupCache[T any](lookup LookupFunc[T], ttl time.Duration) *LookupCache[T] {
 	return &LookupCache[T]{
 		value:  nil,
 		lookup: lookup,

util/util_test.go

@@ -2,6 +2,7 @@ package util
 
 import (
 	"errors"
+	"golang.org/x/time/rate"
 	"io"
 	"net/netip"
 	"os"
@@ -245,6 +246,12 @@ func TestMinMax(t *testing.T) {
 	require.Equal(t, 50, MinMax(50, 10, 99))
 }
 
+func TestMax(t *testing.T) {
+	require.Equal(t, 9, Max(1, 9))
+	require.Equal(t, 9, Max(9, 1))
+	require.Equal(t, rate.Every(time.Minute), Max(rate.Every(time.Hour), rate.Every(time.Minute)))
+}
+
 func TestPointerFunctions(t *testing.T) {
 	i, s, ti := Int(99), String("abc"), Time(time.Unix(99, 0))
 	require.Equal(t, 99, *i)