implement ristretto

Author: emad-elsaid

README.md

@@ -124,9 +124,32 @@ var strlen = memoize.NewWithCache(
 )
 ```
 
+### [dgraph-io/ristretto](* https://github.com/dgraph-io/ristretto/v2)
+
+```go 
+import (
+	"github.com/dgraph-io/ristretto/v2"
+	"github.com/emad-elsaid/memoize"
+	"github.com/emad-elsaid/memoize/cache/adapters/dgraphio"
+)
+
+// example from ristretto README.md
+var c, _ = ristretto.NewCache(&ristretto.Config[string, int]{
+	NumCounters: 1e7,     // number of keys to track frequency of (10M).
+	MaxCost:     1 << 30, // maximum cost of cache (1GB).
+	BufferItems: 64,      // number of keys per Get buffer.
+})
+
+var strlen = memoize.NewWithCache(
+	dgraphio.Ristretto(c),
+	func(s string) int {
+		return len(s)
+	},
+)
+```
+
 ### To be implemented
 
-* https://github.com/dgraph-io/ristretto
 * https://github.com/bradfitz/gomemcache
 * https://github.com/redis/go-redis
 * https://github.com/redis/rueidis

cache/adapters/dgraphio/ristretto.go

@@ -0,0 +1,24 @@
+package dgraphio
+
+import "github.com/emad-elsaid/memoize/cache"
+
+type RistrettoCache[K comparable, V any] interface {
+	Get(K) (V, bool)
+	Set(K, V, int64) bool
+}
+
+func Ristretto[K comparable, V any](c RistrettoCache[K, V]) cache.Cacher[K, V] {
+	return &ristretto[K, V]{c}
+}
+
+type ristretto[K comparable, V any] struct {
+	RistrettoCache[K, V]
+}
+
+func (h *ristretto[K, V]) Load(key K) (value V, loaded bool) {
+	return h.RistrettoCache.Get(key)
+}
+
+func (h *ristretto[K, V]) Store(key K, value V) {
+	h.RistrettoCache.Set(key, value, 0)
+}

cache/adapters/dgraphio/ristretto_test.go

@@ -0,0 +1,32 @@
+package dgraphio
+
+import (
+	"testing"
+)
+
+type Mock map[string]int
+
+func (m Mock) Get(k string) (int, bool) {
+	v, ok := m[k]
+	return v, ok
+}
+
+func (m Mock) Set(k string, v int, _ int64) bool {
+	m[k] = v
+	return true
+}
+
+func TestRistretto(t *testing.T) {
+	m := Mock{}
+	cacher := Ristretto(m)
+	cacher.Store("k1", 1)
+
+	v, ok := cacher.Load("k1")
+	if v != 1 {
+		t.Error("Expected", 1, "got", v)
+	}
+
+	if !ok {
+		t.Error("Expected", true, "got", ok)
+	}
+}