Forcing retransmission

The _NETMGR_QOS_FLUSH message lets an application force a retransmission instead of waiting for Qnet to activate its own timeout.

This is useful for periodic detectable hardware failures where the application can take action, instead of enabling shorter timeout periods for Qnet, which would add more load to the system. For example:

#include <sys/netmgr.h>
#include <sys/netmsg.h>

extern int __netmgr_send( void *smsg1, int ssize1, const void *smsg2,
                          int ssize2, void *rmsg, int rsize);
int main (void)
            struct _io_msg msg;

            msg.type = _IO_MSG;
            msg.combine_len = sizeof(msg);
            msg.mgrid = _IOMGR_NETMGR;
            msg.subtype = _NETMGR_QOS_FLUSH;

            __netmgr_send(&msg, sizeof(msg), 0, 0, 0, 0);