SOCKETSIG_WRITE
ASSERT(event & (SOCKETSIG_WRITE | SOCKETSIG_READ | SOCKETSIG_URG));
if (event & SOCKETSIG_WRITE) {
socket_sendsig(so, SOCKETSIG_WRITE);
socket_sendsig(so, SOCKETSIG_WRITE|SOCKETSIG_READ);
*sigev |= SOCKETSIG_WRITE;
socket_sendsig(so, SOCKETSIG_WRITE);