add WithDistinctResourceTypes server option to override the channel c…

…apacity when Config consists of the greater number of resource types

Signed-off-by: Ilya Lobkov <ilya.lobkov@konghq.com>

pkg/server/config/config.go

@@ -1,15 +1,19 @@
 package config
 
+import "github.com/envoyproxy/go-control-plane/pkg/cache/types"
+
 // Opts for individual xDS implementations that can be
 // utilized through the functional opts pattern.
 type Opts struct {
 	// If true respond to ADS requests with a guaranteed resource ordering
-	Ordered bool
+	Ordered               bool
+	DistinctResourceTypes int
 }
 
 func NewOpts() Opts {
 	return Opts{
-		Ordered: false,
+		Ordered:               false,
+		DistinctResourceTypes: int(types.UnknownType),
 	}
 }
 

pkg/server/delta/v3/server.go

@@ -37,6 +37,14 @@ type Callbacks interface {
 
 var deltaErrorResponse = &cache.RawDeltaResponse{}
 
+// WithDistinctResourceTypes overrides the default number of resource types, so that the server can serve Configs with
+// more distinct resource types without getting into a deadlock.
+func WithDistinctResourceTypes(n int) config.XDSOption {
+	return func(o *config.Opts) {
+		o.DistinctResourceTypes = n
+	}
+}
+
 type server struct {
 	cache     cache.ConfigWatcher
 	callbacks Callbacks
@@ -72,7 +80,7 @@ func (s *server) processDelta(str stream.DeltaStream, reqCh <-chan *discovery.De
 	var streamNonce int64
 
 	// a collection of stack allocated watches per request type
-	watches := newWatches()
+	watches := newWatches(s.opts.DistinctResourceTypes)
 
 	node := &core.Node{}
 

pkg/server/delta/v3/watches.go

@@ -1,7 +1,6 @@
 package delta
 
 import (
-	"github.com/envoyproxy/go-control-plane/pkg/cache/types"
 	"github.com/envoyproxy/go-control-plane/pkg/cache/v3"
 	"github.com/envoyproxy/go-control-plane/pkg/server/stream/v3"
 )
@@ -15,15 +14,15 @@ type watches struct {
 }
 
 // newWatches creates and initializes watches.
-func newWatches() watches {
+func newWatches(distinctResourceTypes int) watches {
 	// deltaMuxedResponses needs a buffer to release go-routines populating it
 	//
 	// because deltaMuxedResponses can be populated by an update from the cache
 	// and a request from the client, we need to create the channel with a buffer
 	// size of 2x the number of types to avoid deadlocks.
 	return watches{
-		deltaWatches:        make(map[string]watch, int(types.UnknownType)),
-		deltaMuxedResponses: make(chan cache.DeltaResponse, int(types.UnknownType)*2),
+		deltaWatches:        make(map[string]watch, distinctResourceTypes),
+		deltaMuxedResponses: make(chan cache.DeltaResponse, distinctResourceTypes*2),
 	}
 }
 

pkg/server/delta/v3/watches_test.go

@@ -5,11 +5,13 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+
+	"github.com/envoyproxy/go-control-plane/pkg/cache/types"
 )
 
 func TestDeltaWatches(t *testing.T) {
 	t.Run("watches response channels are properly closed when the watches are canceled", func(t *testing.T) {
-		watches := newWatches()
+		watches := newWatches(int(types.UnknownType))
 
 		cancelCount := 0
 		// create a few watches, and ensure that the cancel function are called and the channels are closed