assert(priv->ctx->async_fd > 0);
flags = fcntl(priv->ctx->async_fd, F_GETFL);
rc = fcntl(priv->ctx->async_fd, F_SETFL, flags | O_NONBLOCK);
assert(priv->ctx->async_fd > 0);
flags = fcntl(priv->ctx->async_fd, F_GETFL);
rc = fcntl(priv->ctx->async_fd, F_SETFL, flags | O_NONBLOCK);