stub of tiered cache

cache/interface.go

@@ -0,0 +1,6 @@
+package cache
+
+type Interface[K comparable, V any] interface {
+	Get(key K) V
+	Put(key K, value V)
+}

cache/tiered.go

@@ -0,0 +1,34 @@
+package cache
+
+import "reflect"
+
+type tieredCache[K comparable, V any] struct {
+	inner Interface[K, V]
+	outer Interface[K, V]
+}
+
+func NewTieredCache[K comparable, V any](inner, outer Interface[K, V]) Interface[K, V] {
+	return &tieredCache[K, V]{
+		inner: inner,
+		outer: outer,
+	}
+}
+
+func (t *tieredCache[K, V]) Get(key K) V {
+	var zero, value V
+	value = t.inner.Get(key)
+	if reflect.DeepEqual(value, zero) {
+		value = t.outer.Get(key)
+		// if required, add value to inner cache for future requests
+	}
+	return value
+}
+
+func (t *tieredCache[K, V]) Put(key K, value V) {
+	t.inner.Put(key, value)
+
+	// add key to outer cache asynchronously
+	go func(key K) {
+		t.outer.Put(key, value)
+	}(key)
+}