feat: Turn on rbac check caching (#6202)

* chore: Turn on rbac check caching.

Should not affect much unless authz_querier experiment is
enabled

coderd/rbac/authz.go

@@ -158,6 +158,13 @@ var (
 	partialQuery rego.PreparedPartialQuery
 )
 
+// NewCachingAuthorizer returns a new RegoAuthorizer that supports context based
+// caching. To utilize the caching, the context passed to Authorize() must be
+// created with 'WithCacheCtx(ctx)'.
+func NewCachingAuthorizer(registry prometheus.Registerer) Authorizer {
+	return Cacher(NewAuthorizer(registry))
+}
+
 func NewAuthorizer(registry prometheus.Registerer) *RegoAuthorizer {
 	queryOnce.Do(func() {
 		var err error

coderd/rbac/authz_test.go

@@ -109,7 +109,7 @@ func BenchmarkRBACAuthorize(b *testing.B) {
 		uuid.MustParse("0632b012-49e0-4d70-a5b3-f4398f1dcd52"),
 		uuid.MustParse("70dbaa7a-ea9c-4f68-a781-97b08af8461d"),
 	)
-	authorizer := rbac.NewAuthorizer(prometheus.NewRegistry())
+	authorizer := rbac.NewCachingAuthorizer(prometheus.NewRegistry())
 	// This benchmarks all the simple cases using just user permissions. Groups
 	// are added as noise, but do not do anything.
 	for _, c := range benchCases {
@@ -136,7 +136,7 @@ func BenchmarkRBACAuthorizeGroups(b *testing.B) {
 		uuid.MustParse("0632b012-49e0-4d70-a5b3-f4398f1dcd52"),
 		uuid.MustParse("70dbaa7a-ea9c-4f68-a781-97b08af8461d"),
 	)
-	authorizer := rbac.NewAuthorizer(prometheus.NewRegistry())
+	authorizer := rbac.NewCachingAuthorizer(prometheus.NewRegistry())
 
 	// Same benchmark cases, but this time groups will be used to match.
 	// Some '*' permissions will still match, but using a fake action reduces
@@ -188,7 +188,7 @@ func BenchmarkRBACFilter(b *testing.B) {
 		uuid.MustParse("70dbaa7a-ea9c-4f68-a781-97b08af8461d"),
 	)
 
-	authorizer := rbac.NewAuthorizer(prometheus.NewRegistry())
+	authorizer := rbac.NewCachingAuthorizer(prometheus.NewRegistry())
 
 	for _, c := range benchCases {
 		b.Run("PrepareOnly-"+c.Name, func(b *testing.B) {

coderd/rbac/builtin_test.go

@@ -23,7 +23,7 @@ type authSubject struct {
 func TestRolePermissions(t *testing.T) {
 	t.Parallel()
 
-	auth := rbac.NewAuthorizer(prometheus.NewRegistry())
+	auth := rbac.NewCachingAuthorizer(prometheus.NewRegistry())
 
 	// currentUser is anything that references "me", "mine", or "my".
 	currentUser := uuid.New()

coderd/rbac/cache.go

@@ -20,6 +20,8 @@ type cachedCalls struct {
 // multiple calls are made to the Authorizer for the same subject, action, and
 // object. The cache is on each `ctx` and is not shared between requests.
 // If no cache is found on the context, the Authorizer is called as normal.
+//
+// Cacher is safe for multiple actors.
 func Cacher(authz Authorizer) Authorizer {
 	return &cachedCalls{authz: authz}
 }

coderd/rbac/cache_test.go

@@ -2,6 +2,7 @@ package rbac_test
 
 import (
 	"context"
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -10,6 +11,33 @@ import (
 	"github.com/coder/coder/coderd/rbac"
 )
 
+// BenchmarkCacher benchmarks the performance of the cacher with a given
+// cache size. The expected cache size in prod will usually be 1-2. In Filter
+// cases it can get as high as 10.
+func BenchmarkCacher(b *testing.B) {
+	b.ResetTimer()
+	// Size of the cache.
+	sizes := []int{1, 10, 100, 1000}
+	for _, size := range sizes {
+		b.Run(fmt.Sprintf("Size%d", size), func(b *testing.B) {
+			ctx := rbac.WithCacheCtx(context.Background())
+			authz := rbac.Cacher(&coderdtest.FakeAuthorizer{AlwaysReturn: nil})
+			for i := 0; i < size; i++ {
+				// Preload the cache of a given size
+				subj, obj, action := coderdtest.RandomRBACSubject(), coderdtest.RandomRBACObject(), coderdtest.RandomRBACAction()
+				_ = authz.Authorize(ctx, subj, action, obj)
+			}
+
+			// Cache is loaded as a slice, so this cache hit is always the last element.
+			subj, obj, action := coderdtest.RandomRBACSubject(), coderdtest.RandomRBACObject(), coderdtest.RandomRBACAction()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				_ = authz.Authorize(ctx, subj, action, obj)
+			}
+		})
+	}
+}
+
 func TestCacher(t *testing.T) {
 	t.Parallel()