when to call ngx_handle_write_event?i am not really understanded.

[l.jay Yuan]

    rc = WSASend(c->fd, &wsabuf, 1, (DWORD *) &n, 0, ovlp, NULL);

    err = ngx_socket_errno;

    if (rc == 0) {
        if (ovlp != NULL) {
            wev->ovlp.posted_zero_byte = 1;
            wev->ready = 0;
            return NGX_AGAIN;
        }

#if 0 // is test code?
        if ((size_t) n < size) {
            wev->ready = 0;
        }
#endif

2012/6/5 l.jay Yuan <pass86 at gmail.com>:
> when to call ngx_handle_write_event?i am not really understanded.
> who can explain me?