// called via work_queue
void receive_done() {
// Add 1 credit, a receiver has taken a message out of the buffer.
receiver_.add_credit(1);
}
void on_receiver_open(proton::receiver& r) override {
receiver_ = r;
std::lock_guard<std::mutex> l(lock_);
work_queue_ = &receiver_.work_queue();
receiver_.add_credit(MAX_BUFFER); // Buffer is empty, initial credit is the limit
}