Add caching to minimize lookup time (closes #12)

pkg/geoloc/cache.go

@@ -0,0 +1,29 @@
+package geoloc
+
+import (
+	"sync"
+	"time"
+)
+
+var IPCache *Cache
+
+type Cache struct {
+	store sync.Map
+}
+
+func NewCache() *Cache {
+	return &Cache{}
+}
+
+func (c *Cache) Set(key, value uint, ttl time.Duration) {
+	c.store.Store(key, value)
+	time.AfterFunc(ttl, func() {
+		c.store.Delete(key)
+	})
+}
+
+func (c *Cache) Get(key uint) (uint, bool) {
+	output, _ := c.store.Load(key)
+	value, ok := output.(uint)
+	return value, ok
+}