unsigned pa_aupdate_write_begin(pa_aupdate *a) {
unsigned n;
pa_assert(a);
pa_mutex_lock(a->write_lock);
n = (unsigned) pa_atomic_load(&a->read_lock);
a->swapped = false;
return !WHICH(n);
}
unsigned pa_aupdate_read_begin(pa_aupdate *a) {
unsigned n;
pa_assert(a);
/* Increase the lock counter */
n = (unsigned) pa_atomic_inc(&a->read_lock);
/* When n is 0 we have about 2^31 threads running that all try to
* access the data at the same time, oh my! */
pa_assert(COUNTER(n)+1 > 0);
/* The uppermost bit tells us which data to look at */
return WHICH(n);
}
unsigned pa_aupdate_write_swap(pa_aupdate *a) {
unsigned n;
pa_assert(a);
for (;;) {
n = (unsigned) pa_atomic_load(&a->read_lock);
/* If the read counter is > 0 wait; if it is 0 try to swap the lists */
if (COUNTER(n) > 0)
pa_semaphore_wait(a->semaphore);
else if (pa_atomic_cmpxchg(&a->read_lock, (int) n, (int) (n ^ MSB)))
break;
}
a->swapped = true;
return WHICH(n);
}
void check_topology(int Tflag, int argc, char **argv)
{
extern int application_bounds(int *minmsg, int *maxmsg);
extern int check_ethernets(BOOL **adj);
CnetAddr a;
NODEATTR *na;
int n, p, nrouters;
int x, y, rootn;
int appl_minmsg, appl_maxmsg;
LINK *lp;
BOOL **adj;
for(n=0, nrouters=0 ; n<_NNODES ; n++) {
extern char *random_osname(int randint);
/* ASSIGN A RANDOM OPERATING SYSTEM TYPE IF NECESSARY */
if(NP[n].nodetype == NT_ROUTER)
++nrouters;
else if(NP[n].nattr.osname == (char *)NULL)
NP[n].nattr.osname = random_osname((int)nrand48(xsubi));
}
n = _NNODES - nrouters;
if(dflag)
fprintf(stderr,"%d host%s, %d router%s and %d link%s\n",
P(n), P(nrouters), P(_NLINKS) );
/* ENSURE THAT WE HAVE AT LEAST 2 HOSTS (APPLICATION LAYERS) */
if(n < 2) {
fputs("A network must have >= 2 hosts\n",stderr);
++nerrors;
}
application_bounds(&appl_minmsg, &appl_maxmsg);
for(n=0 ; n<(_NNODES-1) ; n++) {
int my_minmsg;
int my_maxmsg;
/* NEXT, CHECK FOR DUPLICATE USER-SPECIFIED NODE ADDRESSES */
na = &NP[n].nattr;
a = na->address;
for(p=n+1 ; p<_NNODES ; p++)
if(a == NP[p].nattr.address) {
fprintf(stderr, "%s and %s have the same node address (%u)\n",
NP[n].nodename, NP[p].nodename, a);
++nerrors;
}
/* CHECK THAT USER-REQUESTED MESSAGE SIZES ARE NEITHER TOO BIG NOR TOO SMALL */
my_minmsg = WHICH(na->minmessagesize, DEFAULTNODE.minmessagesize);
my_maxmsg = WHICH(na->maxmessagesize, DEFAULTNODE.maxmessagesize);
if(my_minmsg < appl_minmsg) {
fprintf(stderr,
"%s has minmessagesize(=%d) < application layer requirements(=%d)\n",
NP[n].nodename, my_minmsg, appl_minmsg);
++nerrors;
}
if(my_maxmsg > appl_maxmsg) {
fprintf(stderr,
"%s has maxmessagesize(=%d) > application layer requirements(=%d)\n",
NP[n].nodename, my_maxmsg, appl_maxmsg);
++nerrors;
}
if(my_minmsg > my_maxmsg) {
fprintf(stderr,"%s has minmessagesize(=%d) > maxmessagesize(=%d)\n",
NP[n].nodename, my_minmsg, my_maxmsg);
++nerrors;
}
}
/* ALLOCATE AND INITIALIZE THE ADJACENCY MATIRX (CHECK FOR ETHERNETS TOO) */
adj = (BOOL **)malloc(_NNODES * sizeof(BOOL *));
for(n=0 ; n<_NNODES ; ++n) {
adj[n] = (BOOL *)malloc(_NNODES * sizeof(BOOL));
memset(adj[n], 0, _NNODES * sizeof(BOOL));
}
check_ethernets(adj);
/* IF ANY SIGNIFICANT ERRORS OCCURED, TERMINATE THE PROGRAM */
if(nerrors)
cleanup(1);
rootn = (int)sqrt((double)(_NNODES-1)) + 1;
for(n=0 ; n < _NNODES ; n++) {
na = &NP[n].nattr;
x = n%rootn;
y = n/rootn;
/* GIVE SOME DEFAULT X,Y COORDINATES IF THEY HAVE NOT BEEN SPECIFIED */
if(na->x == 0)
na->x = (2*x+1) * DEF_NODE_X;
if(na->y == 0)
na->y = (2*y+1) * DEF_NODE_Y;
if(na->winx == 0)
na->winx = (5*x+1) * DEF_NODE_X;
if(na->winy == 0)
na->winy = (5*y+1) * DEF_NODE_Y;
/* ADD ANY REBOOT ARGUMENTS IF NOT PROVIDED BY TOPOLOGY FILE */
if(na->reboot_args == (char **)NULL)
init_reboot_args(na, argc, argv);
}
/* NEXT, PROVIDE A WARNING (ONLY) IF THE TOPOLOGY IS NOT CONNECTED */
for(n=0, lp=LP ; n<_NLINKS ; n++, lp++)
if(LP[n].linktype == LT_POINT2POINT) {
int from = lp->endmin;
int to = lp->endmax;
adj[from][to] = adj[to][from] = TRUE;
}
if(!connected(_NNODES, adj))
fprintf(stderr, "*** warning: this topology is not connected\n");
for(n=0 ; n<_NNODES ; ++n)
free(adj[n]);
free(adj);
/* IF ATTEMPTING TO DRAWN FRAMES IN A 2-NODE WORLD (ONLY), POSITION NODES */
if(_NNODES == 2 && gattr.drawframes && nethernets == 0 && !Tflag && Wflag) {
NP[0].nattr.x = DEF_NODE_X;
NP[0].nattr.y = DEF_NODE_Y;
NP[1].nattr.x = DRAWFRAME_WIDTH - DEF_NODE_X;
NP[1].nattr.y = DEF_NODE_Y;
}
else
gattr.drawframes = FALSE;
}
