Configurable size of validate queue

pubsub.go

@@ -159,7 +159,7 @@ type PubSubRouter interface {
 
 type Message struct {
 	*pb.Message
-	ReceivedFrom peer.ID
+	ReceivedFrom  peer.ID
 	ValidatorData interface{}
 }
 

validation.go

@@ -10,6 +10,7 @@ import (
 )
 
 const (
+	defaultValidateQueueSize   = 32
 	defaultValidateConcurrency = 1024
 	defaultValidateThrottle    = 8192
 )
@@ -82,7 +83,7 @@ type rmValReq struct {
 func newValidation() *validation {
 	return &validation{
 		topicVals:        make(map[string]*topicVal),
-		validateQ:        make(chan *validateReq, 32),
+		validateQ:        make(chan *validateReq, defaultValidateQueueSize),
 		validateThrottle: make(chan struct{}, defaultValidateThrottle),
 		validateWorkers:  runtime.NumCPU(),
 	}
@@ -342,6 +343,18 @@ func (val *topicVal) validateMsg(ctx context.Context, src peer.ID, msg *Message)
 
 /// Options
 
+// WithValidateQueueSize sets the buffer of validate queue. Defaults to 32.
+// When queue is full, validation is throttled and new messages are dropped.
+func WithValidateQueueSize(n int) Option {
+	return func(ps *PubSub) error {
+		if n > 0 {
+			ps.val.validateQ = make(chan *validateReq, n)
+			return nil
+		}
+		return fmt.Errorf("validate queue size must be > 0")
+	}
+}
+
 // WithValidateThrottle sets the upper bound on the number of active validation
 // goroutines across all topics. The default is 8192.
 func WithValidateThrottle(n int) Option {