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

plugin/dnssec/cache.go

@@ -23,7 +23,7 @@ func hash(rrs []dns.RR) uint64 {
 	return h.Sum64()
 }
 
-func periodicClean(c *cache.Cache, stop <-chan struct{}) {
+func periodicClean(c *cache.Cache[[]dns.RR], stop <-chan struct{}) {
 	tick := time.NewTicker(8 * time.Hour)
 	defer tick.Stop()
 	for {
@@ -32,8 +32,8 @@ func periodicClean(c *cache.Cache, stop <-chan struct{}) {
 			// we sign for 8 days, check if a signature in the cache reached 75% of that (i.e. 6), if found delete
 			// the signature
 			is75 := time.Now().UTC().Add(twoDays)
-			c.Walk(func(items map[uint64]any, key uint64) bool {
-				for _, rr := range items[key].([]dns.RR) {
+			c.Walk(func(items map[uint64][]dns.RR, key uint64) bool {
+				for _, rr := range items[key] {
 					if !rr.(*dns.RRSIG).ValidityPeriod(is75) {
 						delete(items, key)
 					}

plugin/dnssec/cache_test.go

@@ -7,6 +7,8 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/cache"
 	"github.com/coredns/coredns/plugin/test"
 	"github.com/coredns/coredns/request"
+
+	"github.com/miekg/dns"
 )
 
 func TestCacheSet(t *testing.T) {
@@ -20,7 +22,7 @@ func TestCacheSet(t *testing.T) {
 		t.Fatalf("Failed to parse key: %v\n", err)
 	}
 
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	m := testMsg()
 	state := request.Request{Req: m, Zone: "miek.nl."}
 	k := hash(m.Answer) // calculate *before* we add the sig
@@ -44,7 +46,7 @@ func TestCacheNotValidExpired(t *testing.T) {
 		t.Fatalf("Failed to parse key: %v\n", err)
 	}
 
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	m := testMsg()
 	state := request.Request{Req: m, Zone: "miek.nl."}
 	k := hash(m.Answer) // calculate *before* we add the sig
@@ -68,7 +70,7 @@ func TestCacheNotValidYet(t *testing.T) {
 		t.Fatalf("Failed to parse key: %v\n", err)
 	}
 
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	m := testMsg()
 	state := request.Request{Req: m, Zone: "miek.nl."}
 	k := hash(m.Answer) // calculate *before* we add the sig

plugin/dnssec/dnssec.go

@@ -22,11 +22,11 @@ type Dnssec struct {
 	keys      []*DNSKEY
 	splitkeys bool
 	inflight  *singleflight.Group
-	cache     *cache.Cache
+	cache     *cache.Cache[[]dns.RR]
 }
 
 // New returns a new Dnssec.
-func New(zones []string, keys []*DNSKEY, splitkeys bool, next plugin.Handler, c *cache.Cache) Dnssec {
+func New(zones []string, keys []*DNSKEY, splitkeys bool, next plugin.Handler, c *cache.Cache[[]dns.RR]) Dnssec {
 	return Dnssec{Next: next,
 		zones:     zones,
 		keys:      keys,
@@ -152,7 +152,7 @@ func (d Dnssec) get(key uint64, server string) ([]dns.RR, bool) {
 	if s, ok := d.cache.Get(key); ok {
 		// we sign for 8 days, check if a signature in the cache reached 3/4 of that
 		is75 := time.Now().UTC().Add(twoDays)
-		for _, rr := range s.([]dns.RR) {
+		for _, rr := range s {
 			if !rr.(*dns.RRSIG).ValidityPeriod(is75) {
 				cacheMisses.WithLabelValues(server).Inc()
 				return nil, false
@@ -160,7 +160,7 @@ func (d Dnssec) get(key uint64, server string) ([]dns.RR, bool) {
 		}
 
 		cacheHits.WithLabelValues(server).Inc()
-		return s.([]dns.RR), true
+		return s, true
 	}
 	cacheMisses.WithLabelValues(server).Inc()
 	return nil, false

plugin/dnssec/dnssec_test.go

@@ -69,7 +69,7 @@ func TestSigningDifferentZone(t *testing.T) {
 
 	m := testMsgEx()
 	state := request.Request{Req: m, Zone: "example.org."}
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	d := New([]string{"example.org."}, []*DNSKEY{key}, false, nil, c)
 	m = d.Sign(state, time.Now().UTC(), server)
 	if !section(m.Answer, 1) {
@@ -250,7 +250,7 @@ func testEmptyMsg() *dns.Msg {
 func newDnssec(t *testing.T, zones []string) (Dnssec, func(), func()) {
 	t.Helper()
 	k, rm1, rm2 := newKey(t)
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	d := New(zones, []*DNSKEY{k}, false, nil, c)
 	return d, rm1, rm2
 }

plugin/dnssec/handler_test.go

@@ -170,7 +170,7 @@ func TestLookupZone(t *testing.T) {
 	dnskey, rm1, rm2 := newKey(t)
 	defer rm1()
 	defer rm2()
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	dh := New([]string{"miek.nl."}, []*DNSKEY{dnskey}, false, fm, c)
 
 	for _, tc := range dnsTestCases {
@@ -193,7 +193,7 @@ func TestLookupDNSKEY(t *testing.T) {
 	dnskey, rm1, rm2 := newKey(t)
 	defer rm1()
 	defer rm2()
-	c := cache.New(defaultCap)
+	c := cache.New[[]dns.RR](defaultCap)
 	dh := New([]string{"miek.nl."}, []*DNSKEY{dnskey}, false, test.ErrorHandler(), c)
 
 	for _, tc := range dnssecTestCases {

plugin/dnssec/setup.go

@@ -12,6 +12,8 @@ import (
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/pkg/cache"
 	clog "github.com/coredns/coredns/plugin/pkg/log"
+
+	"github.com/miekg/dns"
 )
 
 var log = clog.NewWithPlugin("dnssec")
@@ -24,7 +26,7 @@ func setup(c *caddy.Controller) error {
 		return plugin.Error("dnssec", err)
 	}
 
-	ca := cache.New(capacity)
+	ca := cache.New[[]dns.RR](capacity)
 	stop := make(chan struct{})
 
 	c.OnShutdown(func() error {

plugin/pkg/cache/cache.go

@@ -16,52 +16,52 @@ func Hash(what []byte) uint64 {
 }
 
 // Cache is cache.
-type Cache struct {
-	shards [shardSize]*shard
+type Cache[T any] struct {
+	shards [shardSize]*shard[T]
 }
 
 // shard is a cache with random eviction.
-type shard struct {
-	items map[uint64]any
+type shard[T any] struct {
+	items map[uint64]T
 	size  int
 
 	sync.RWMutex
 }
 
 // New returns a new cache.
-func New(size int) *Cache {
+func New[T any](size int) *Cache[T] {
 	ssize := max(size/shardSize, 4)
 
-	c := &Cache{}
+	c := &Cache[T]{}
 
 	// Initialize all the shards
 	for i := range shardSize {
-		c.shards[i] = newShard(ssize)
+		c.shards[i] = newShard[T](ssize)
 	}
 	return c
 }
 
 // Add adds a new element to the cache. If the element already exists it is overwritten.
 // Returns true if an existing element was evicted to make room for this element.
-func (c *Cache) Add(key uint64, el any) bool {
+func (c *Cache[T]) Add(key uint64, el T) bool {
 	shard := key & (shardSize - 1)
 	return c.shards[shard].Add(key, el)
 }
 
 // Get looks up element index under key.
-func (c *Cache) Get(key uint64) (any, bool) {
+func (c *Cache[T]) Get(key uint64) (T, bool) {
 	shard := key & (shardSize - 1)
 	return c.shards[shard].Get(key)
 }
 
 // Remove removes the element indexed with key.
-func (c *Cache) Remove(key uint64) {
+func (c *Cache[T]) Remove(key uint64) {
 	shard := key & (shardSize - 1)
 	c.shards[shard].Remove(key)
 }
 
 // Len returns the number of elements in the cache.
-func (c *Cache) Len() int {
+func (c *Cache[T]) Len() int {
 	l := 0
 	for _, s := range &c.shards {
 		l += s.Len()
@@ -70,18 +70,18 @@ func (c *Cache) Len() int {
 }
 
 // Walk walks each shard in the cache.
-func (c *Cache) Walk(f func(map[uint64]any, uint64) bool) {
+func (c *Cache[T]) Walk(f func(map[uint64]T, uint64) bool) {
 	for _, s := range &c.shards {
 		s.Walk(f)
 	}
 }
 
 // newShard returns a new shard with size.
-func newShard(size int) *shard { return &shard{items: make(map[uint64]any), size: size} }
+func newShard[T any](size int) *shard[T] { return &shard[T]{items: make(map[uint64]T), size: size} }
 
 // Add adds element indexed by key into the cache. Any existing element is overwritten
 // Returns true if an existing element was evicted to make room for this element.
-func (s *shard) Add(key uint64, el any) bool {
+func (s *shard[T]) Add(key uint64, el T) bool {
 	eviction := false
 	s.Lock()
 	if len(s.items) >= s.size {
@@ -99,14 +99,14 @@ func (s *shard) Add(key uint64, el any) bool {
 }
 
 // Remove removes the element indexed by key from the cache.
-func (s *shard) Remove(key uint64) {
+func (s *shard[T]) Remove(key uint64) {
 	s.Lock()
 	delete(s.items, key)
 	s.Unlock()
 }
 
 // Evict removes a random element from the cache.
-func (s *shard) Evict() {
+func (s *shard[T]) Evict() {
 	s.Lock()
 	for k := range s.items {
 		delete(s.items, k)
@@ -116,7 +116,7 @@ func (s *shard) Evict() {
 }
 
 // Get looks up the element indexed under key.
-func (s *shard) Get(key uint64) (any, bool) {
+func (s *shard[T]) Get(key uint64) (T, bool) {
 	s.RLock()
 	el, found := s.items[key]
 	s.RUnlock()
@@ -124,7 +124,7 @@ func (s *shard) Get(key uint64) (any, bool) {
 }
 
 // Len returns the current length of the cache.
-func (s *shard) Len() int {
+func (s *shard[T]) Len() int {
 	s.RLock()
 	l := len(s.items)
 	s.RUnlock()
@@ -132,7 +132,7 @@ func (s *shard) Len() int {
 }
 
 // Walk walks the shard for each element the function f is executed while holding a write lock.
-func (s *shard) Walk(f func(map[uint64]any, uint64) bool) {
+func (s *shard[T]) Walk(f func(map[uint64]T, uint64) bool) {
 	s.RLock()
 	items := make([]uint64, len(s.items))
 	i := 0

plugin/pkg/cache/cache_test.go

@@ -6,7 +6,7 @@ import (
 
 func TestCacheAddAndGet(t *testing.T) {
 	const N = shardSize * 4
-	c := New(N)
+	c := New[int](N)
 	c.Add(1, 1)
 
 	if _, found := c.Get(1); !found {
@@ -25,7 +25,7 @@ func TestCacheAddAndGet(t *testing.T) {
 }
 
 func TestCacheLen(t *testing.T) {
-	c := New(4)
+	c := New[int](4)
 
 	c.Add(1, 1)
 	if l := c.Len(); l != 1 {
@@ -44,7 +44,7 @@ func TestCacheLen(t *testing.T) {
 }
 
 func TestCacheSharding(t *testing.T) {
-	c := New(shardSize)
+	c := New[int](shardSize)
 	for i := range shardSize * 2 {
 		c.Add(uint64(i), 1)
 	}
@@ -56,15 +56,15 @@ func TestCacheSharding(t *testing.T) {
 }
 
 func TestCacheWalk(t *testing.T) {
-	c := New(10)
+	c := New[int](10)
 	exp := make([]int, 10*2)
 	for i := range 10 * 2 {
 		c.Add(uint64(i), 1)
 		exp[i] = 1
 	}
 	got := make([]int, 10*2)
-	c.Walk(func(items map[uint64]any, key uint64) bool {
-		got[key] = items[key].(int)
+	c.Walk(func(items map[uint64]int, key uint64) bool {
+		got[key] = items[key]
 		return true
 	})
 	for i := range exp {
@@ -77,7 +77,7 @@ func TestCacheWalk(t *testing.T) {
 func BenchmarkCache(b *testing.B) {
 	b.ReportAllocs()
 
-	c := New(4)
+	c := New[int](4)
 	for b.Loop() {
 		c.Add(1, 1)
 		c.Get(1)

plugin/pkg/cache/shard_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestShardAddAndGet(t *testing.T) {
-	s := newShard(1)
+	s := newShard[int](1)
 	s.Add(1, 1)
 
 	if _, found := s.Get(1); !found {
@@ -24,7 +24,7 @@ func TestShardAddAndGet(t *testing.T) {
 
 func TestAddEvict(t *testing.T) {
 	const size = 1024
-	s := newShard(size)
+	s := newShard[int](size)
 
 	for i := range size {
 		s.Add(uint64(i), 1)
@@ -38,7 +38,7 @@ func TestAddEvict(t *testing.T) {
 }
 
 func TestShardLen(t *testing.T) {
-	s := newShard(4)
+	s := newShard[int](4)
 
 	s.Add(1, 1)
 	if l := s.Len(); l != 1 {
@@ -57,7 +57,7 @@ func TestShardLen(t *testing.T) {
 }
 
 func TestShardEvict(t *testing.T) {
-	s := newShard(1)
+	s := newShard[int](1)
 	s.Add(1, 1)
 	s.Add(2, 2)
 	// 1 should be gone
@@ -68,7 +68,7 @@ func TestShardEvict(t *testing.T) {
 }
 
 func TestShardLenEvict(t *testing.T) {
-	s := newShard(4)
+	s := newShard[int](4)
 	s.Add(1, 1)
 	s.Add(2, 1)
 	s.Add(3, 1)
@@ -95,7 +95,7 @@ func TestShardLenEvict(t *testing.T) {
 }
 
 func TestShardEvictParallel(t *testing.T) {
-	s := newShard(shardSize)
+	s := newShard[struct{}](shardSize)
 	for i := range shardSize {
 		s.Add(uint64(i), struct{}{})
 	}
@@ -117,7 +117,7 @@ func TestShardEvictParallel(t *testing.T) {
 }
 
 func BenchmarkShard(b *testing.B) {
-	s := newShard(shardSize)
+	s := newShard[int](shardSize)
 	b.ResetTimer()
 	for i := range b.N {
 		k := uint64(i) % shardSize * 2
@@ -127,7 +127,7 @@ func BenchmarkShard(b *testing.B) {
 }
 
 func BenchmarkShardParallel(b *testing.B) {
-	s := newShard(shardSize)
+	s := newShard[int](shardSize)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		for i := uint64(0); pb.Next(); i++ {