install global validation throttle, use reasonable defaults.

floodsub.go

@@ -19,8 +19,9 @@ import (
 
 const (
 	ID                         = protocol.ID("/floodsub/1.0.0")
-	defaultValidateConcurrency = 10
 	defaultValidateTimeout     = 150 * time.Millisecond
+	defaultValidateConcurrency = 100
+	defaultValidateThrottle    = 8192
 )
 
 var log = logging.Logger("floodsub")
@@ -61,6 +62,9 @@ type PubSub struct {
 	// sendMsg handles messages that have been validated
 	sendMsg chan *sendReq
 
+	// validateThrottle limits the number of active validation goroutines
+	validateThrottle chan struct{}
+
 	peers        map[peer.ID]chan *RPC
 	seenMessages *timecache.TimeCache
 
@@ -101,6 +105,7 @@ func NewFloodSub(ctx context.Context, h host.Host, opts ...Option) (*PubSub, err
 		addSub:           make(chan *addSubReq),
 		getTopics:        make(chan *topicReq),
 		sendMsg:          make(chan *sendReq),
+		validateThrottle: make(chan struct{}, defaultValidateThrottle),
 		myTopics:         make(map[string]map[*Subscription]struct{}),
 		topics:           make(map[string]map[peer.ID]struct{}),
 		peers:            make(map[peer.ID]chan *RPC),
@@ -123,6 +128,13 @@ func NewFloodSub(ctx context.Context, h host.Host, opts ...Option) (*PubSub, err
 	return ps, nil
 }
 
+func WithValidateThrottle(n int) Option {
+	return func(ps *PubSub) error {
+		ps.validateThrottle = make(chan struct{}, n)
+		return nil
+	}
+}
+
 // processLoop handles all inputs arriving on the channels
 func (p *PubSub) processLoop(ctx context.Context) {
 	defer func() {
@@ -361,9 +373,16 @@ func (p *PubSub) pushMsg(subs []*Subscription, src peer.ID, msg *Message) {
 	}
 
 	if needval {
-		// validation is asynchronous
-		// XXX vyzo: do we want a global validation throttle here?
-		go p.validate(subs, src, msg)
+		// validation is asynchronous and globally throttled with the throttleValidate semaphore
+		select {
+		case p.validateThrottle <- struct{}{}:
+			go func() {
+				p.validate(subs, src, msg)
+				<-p.validateThrottle
+			}()
+		default:
+			log.Warningf("message validation throttled; dropping message from %s", src)
+		}
 		return
 	}