fix: increase gsoc websocket buffer to absorb legitimate bursts

dataC's buffer of 2 was too small for a legitimate burst of GSOC
messages delivered concurrently to the same subscriber (e.g. several
chunks pushed at once), causing a false-positive slow-consumer
disconnect. Bump it to 16 and adjust the slow-consumer test's message
count so overflow is still hit deterministically.

Author: nugaon

pkg/api/gsoc.go

@@ -171,7 +171,10 @@ func (s *Service) gsocListeningWs(conn *websocket.Conn, socAddress swarm.Address
 	defer s.wsWg.Done()
 
 	var (
-		dataC    = make(chan []byte, 2) // small buffer to decouple producer/consumer
+		// Buffered enough to absorb a legitimate burst of concurrently delivered
+		// GSOC messages (e.g. several chunks pushed to this address at once)
+		// without tripping the slow-consumer detection below.
+		dataC    = make(chan []byte, 16)
 		gone     = make(chan struct{})
 		slow     = make(chan struct{})
 		slowOnce sync.Once

pkg/api/gsoc_test.go

@@ -290,7 +290,7 @@ func TestGsocWebsocketInvalidFieldsHeader(t *testing.T) {
 func TestGsocWebsocketSlowConsumer(t *testing.T) {
 	t.Parallel()
 
-	const messageCount = 10
+	const messageCount = 32 // exceeds dataC's buffer so the overflow is hit deterministically
 
 	var (
 		id         = make([]byte, 32)