#6

pokecache/pokecache.go

@@ -0,0 +1,64 @@
+package pokecache
+
+import (
+	"sync"
+	"time"
+)
+
+// Cache -
+type Cache struct {
+	cache map[string]cacheEntry
+	mux   *sync.Mutex
+}
+
+type cacheEntry struct {
+	createdAt time.Time
+	val       []byte
+}
+
+// NewCache -
+func NewCache(interval time.Duration) Cache {
+	c := Cache{
+		cache: make(map[string]cacheEntry),
+		mux:   &sync.Mutex{},
+	}
+
+	go c.reapLoop(interval)
+
+	return c
+}
+
+// Add -
+func (c *Cache) Add(key string, value []byte) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	c.cache[key] = cacheEntry{
+		createdAt: time.Now().UTC(),
+		val:       value,
+	}
+}
+
+// Get -
+func (c *Cache) Get(key string) ([]byte, bool) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	val, ok := c.cache[key]
+	return val.val, ok
+}
+
+func (c *Cache) reapLoop(interval time.Duration) {
+	ticker := time.NewTicker(interval)
+	for range ticker.C {
+		c.reap(time.Now().UTC(), interval)
+	}
+}
+
+func (c *Cache) reap(now time.Time, last time.Duration) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	for k, v := range c.cache {
+		if v.createdAt.Before(now.Add(-last)) {
+			delete(c.cache, k)
+		}
+	}
+}

pokecache/pokecache_test.go

@@ -0,0 +1,61 @@
+package pokecache
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func TestAddGet(t *testing.T) {
+	const interval = 5 * time.Second
+	cases := []struct {
+		key string
+		val []byte
+	}{
+		{
+			key: "https://example.com",
+			val: []byte("testdata"),
+		},
+		{
+			key: "https://example.com/path",
+			val: []byte("moretestdata"),
+		},
+	}
+
+	for i, c := range cases {
+		t.Run(fmt.Sprintf("Test case %v", i), func(t *testing.T) {
+			cache := NewCache(interval)
+			cache.Add(c.key, c.val)
+			val, ok := cache.Get(c.key)
+			if !ok {
+				t.Errorf("expected to find key")
+				return
+			}
+			if string(val) != string(c.val) {
+				t.Errorf("expected to find value")
+				return
+			}
+		})
+	}
+}
+
+func TestReapLoop(t *testing.T) {
+	const baseTime = 5 * time.Millisecond
+	const waitTime = baseTime + 5*time.Millisecond
+	cache := NewCache(baseTime)
+	cache.Add("https://example.com", []byte("testdata"))
+
+	_, ok := cache.Get("https://example.com")
+	if !ok {
+		t.Errorf("expected to find key")
+		return
+	}
+
+	time.Sleep(waitTime)
+
+	_, ok = cache.Get("https://example.com")
+	if ok {
+		t.Errorf("expected to not find key")
+		return
+	}
+}