Refactor handler to wait for cwnd space.

prrt/proto/processes/dataTransmitter.c

@@ -95,14 +95,12 @@ static bool send_packet(PrrtSocket *sock_ptr, PrrtPacket *packet) {
         usleep_nano(1);
     }
 
-    int64_t space, cwnd, pipe;
-    do {
-        cwnd = (int64_t) PrrtReceiver_getBBRCwnd(sock_ptr->receiver);
-        pipe = (int64_t) PrrtReceiver_get_pipe(sock_ptr->receiver);
-        space = cwnd - pipe;
-        usleep_nano(100);
+    int64_t space = PrrtReceiver_get_space(sock_ptr->receiver);
+    while (space < sock_ptr->mtu) {
         //PrrtReceiver_check_rto(sock_ptr->receiver, packet->sequenceNumber, PrrtPacket_type(packet));
-    } while(space < sock_ptr->mtu);
+        PrrtReceiver_wait_for_space(sock_ptr->receiver);
+        space = PrrtReceiver_get_space(sock_ptr->receiver);
+    }
 
     prrtTimestamp_t now = PrrtClock_get_current_time_us();
     if (sock_ptr->pacingEnabled) {