refactor(cache): modernize with generics (#7842)

plugin/cache/cache.go

@@ -24,12 +24,12 @@ type Cache struct {
 	zonesMetricLabel string
 	viewMetricLabel  string
 
-	ncache  *cache.Cache
+	ncache  *cache.Cache[*item]
 	ncap    int
 	nttl    time.Duration
 	minnttl time.Duration
 
-	pcache  *cache.Cache
+	pcache  *cache.Cache[*item]
 	pcap    int
 	pttl    time.Duration
 	minpttl time.Duration
@@ -61,11 +61,11 @@ func New() *Cache {
 	return &Cache{
 		Zones:      []string{"."},
 		pcap:       defaultCap,
-		pcache:     cache.New(defaultCap),
+		pcache:     cache.New[*item](defaultCap),
 		pttl:       maxTTL,
 		minpttl:    minTTL,
 		ncap:       defaultCap,
-		ncache:     cache.New(defaultCap),
+		ncache:     cache.New[*item](defaultCap),
 		nttl:       maxNTTL,
 		minnttl:    minNTTL,
 		failttl:    minNTTL,

plugin/cache/cache_test.go

@@ -712,8 +712,8 @@ func TestCacheWildcardMetadata(t *testing.T) {
 	}
 	_, k := key(qname, w.Msg, response.NoError, state.Do(), state.Req.CheckingDisabled)
 	i, _ := c.pcache.Get(k)
-	if i.(*item).wildcard != wildcard {
-		t.Errorf("expected wildcard response to enter cache with cache item's wildcard = %q, got %q", wildcard, i.(*item).wildcard)
+	if i.wildcard != wildcard {
+		t.Errorf("expected wildcard response to enter cache with cache item's wildcard = %q, got %q", wildcard, i.wildcard)
 	}
 
 	// 2. Test retrieving the cached item from cache and writing its wildcard value to metadata
@@ -728,7 +728,7 @@ func TestCacheWildcardMetadata(t *testing.T) {
 		t.Fatal("expected metadata func for wildcard response retrieved from cache, got nil")
 	}
 	if f() != wildcard {
-		t.Errorf("after retrieving wildcard item from cache, expected \"zone/wildcard\" metadata value to be %q, got %q", wildcard, i.(*item).wildcard)
+		t.Errorf("after retrieving wildcard item from cache, expected \"zone/wildcard\" metadata value to be %q, got %q", wildcard, i.wildcard)
 	}
 }
 

plugin/cache/handler.go

@@ -127,19 +127,17 @@ func (c *Cache) getIfNotStale(now time.Time, state request.Request, server strin
 	cacheRequests.WithLabelValues(server, c.zonesMetricLabel, c.viewMetricLabel).Inc()
 
 	if i, ok := c.ncache.Get(k); ok {
-		itm := i.(*item)
-		ttl := itm.ttl(now)
-		if itm.matches(state) && (ttl > 0 || (c.staleUpTo > 0 && -ttl < int(c.staleUpTo.Seconds()))) {
+		ttl := i.ttl(now)
+		if i.matches(state) && (ttl > 0 || (c.staleUpTo > 0 && -ttl < int(c.staleUpTo.Seconds()))) {
 			cacheHits.WithLabelValues(server, Denial, c.zonesMetricLabel, c.viewMetricLabel).Inc()
-			return i.(*item)
+			return i
 		}
 	}
 	if i, ok := c.pcache.Get(k); ok {
-		itm := i.(*item)
-		ttl := itm.ttl(now)
-		if itm.matches(state) && (ttl > 0 || (c.staleUpTo > 0 && -ttl < int(c.staleUpTo.Seconds()))) {
+		ttl := i.ttl(now)
+		if i.matches(state) && (ttl > 0 || (c.staleUpTo > 0 && -ttl < int(c.staleUpTo.Seconds()))) {
 			cacheHits.WithLabelValues(server, Success, c.zonesMetricLabel, c.viewMetricLabel).Inc()
-			return i.(*item)
+			return i
 		}
 	}
 	cacheMisses.WithLabelValues(server, c.zonesMetricLabel, c.viewMetricLabel).Inc()
@@ -150,10 +148,10 @@ func (c *Cache) getIfNotStale(now time.Time, state request.Request, server strin
 func (c *Cache) exists(state request.Request) *item {
 	k := hash(state.Name(), state.QType(), state.Do(), state.Req.CheckingDisabled)
 	if i, ok := c.ncache.Get(k); ok {
-		return i.(*item)
+		return i
 	}
 	if i, ok := c.pcache.Get(k); ok {
-		return i.(*item)
+		return i
 	}
 	return nil
 }

plugin/cache/setup.go

@@ -253,8 +253,8 @@ func cacheParse(c *caddy.Controller) (*Cache, error) {
 
 		ca.Zones = origins
 		ca.zonesMetricLabel = strings.Join(origins, ",")
-		ca.pcache = cache.New(ca.pcap)
-		ca.ncache = cache.New(ca.ncap)
+		ca.pcache = cache.New[*item](ca.pcap)
+		ca.ncache = cache.New[*item](ca.ncap)
 	}
 
 	return ca, nil