static SEXP read_child_ci(child_info_t *ci)
{
unsigned int len = 0;
int fd = ci->pfd;
ssize_t n = read(fd, &len, sizeof(len));
#ifdef MC_DEBUG
Dprintf(" read_child_ci(%d) - read length returned %d\n", ci->pid, n);
#endif
if (n != sizeof(len) || len == 0) { /* error or child is exiting */
int pid = ci->pid;
close(fd);
ci->pfd = -1;
rm_child_(pid);
return ScalarInteger(pid);
} else {
SEXP rv = allocVector(RAWSXP, len);
unsigned char *rvb = RAW(rv);
unsigned int i = 0;
while (i < len) {
n = read(fd, rvb + i, len - i);
#ifdef MC_DEBUG
Dprintf(" read_child_ci(%d) - read %d at %d returned %d\n", ci->pid, len-i, i, n);
#endif
if (n < 1) {
int pid = ci->pid;
close(fd);
ci->pfd = -1;
rm_child_(pid);
return ScalarInteger(pid);
}
i += n;
}
PROTECT(rv);
{
SEXP pa = allocVector(INTSXP, 1);
PROTECT(pa);
INTEGER(pa)[0] = ci->pid;
setAttrib(rv, install("pid"), pa);
UNPROTECT(1);
}
UNPROTECT(1);
return rv;
}
}
SEXP mc_rm_child(SEXP sPid)
{
int pid = asInteger(sPid);
return ScalarLogical(rm_child_(pid));
}
SEXP mc_select_children(SEXP sTimeout, SEXP sWhich)
{
int maxfd = 0, sr, zombies = 0;
unsigned int wlen = 0, wcount = 0;
SEXP res;
int *res_i, *which = 0;
child_info_t *ci = children;
fd_set fs;
struct timeval tv = { 0, 0 }, *tvp = &tv;
if (isReal(sTimeout) && LENGTH(sTimeout) == 1) {
double tov = asReal(sTimeout);
if (tov < 0.0) tvp = 0; /* Note: I'm not sure we really should allow this .. */
else {
tv.tv_sec = (int) tov;
tv.tv_usec = (int) ((tov - ((double) tv.tv_sec)) * 1000000.0);
}
}
if (TYPEOF(sWhich) == INTSXP && LENGTH(sWhich)) {
which = INTEGER(sWhich);
wlen = LENGTH(sWhich);
}
{
int wstat;
while (waitpid(-1, &wstat, WNOHANG) > 0) ; /* check for zombies */
}
FD_ZERO(&fs);
while (ci && ci->pid) {
if (ci->pfd == -1) zombies++;
if (ci->pfd > maxfd) maxfd = ci->pfd;
if (ci->pfd > 0) {
if (which) { /* check for the FD only if it's on the list */
unsigned int k = 0;
while (k < wlen)
if (which[k++] == ci->pid) {
FD_SET(ci->pfd, &fs);
wcount++;
break;
}
} else FD_SET(ci->pfd, &fs);
}
ci = ci -> next;
}
#ifdef MC_DEBUG
Dprintf("select_children: maxfd=%d, wlen=%d, wcount=%d, zombies=%d, timeout=%d:%d\n", maxfd, wlen, wcount, zombies, (int)tv.tv_sec, (int)tv.tv_usec);
#endif
if (zombies) { /* oops, this should never really happen - it did
* while we had a bug in rm_child_ but hopefully
* not anymore */
while (zombies) { /* this is rather more complicated than it
* should be if we used pointers to delete,
* but well ... */
ci = children;
while (ci) {
if (ci->pfd == -1) {
#ifdef MC_DEBUG
Dprintf("detected zombie: pid=%d, pfd=%d, sifd=%d\n",
ci->pid, ci->pfd, ci->sifd);
#endif
rm_child_(ci->pid);
zombies--;
break;
}
ci = ci->next;
}
if (!ci) break;
}
}
if (maxfd == 0 || (wlen && !wcount))
return R_NilValue; /* NULL signifies no children to tend to */
sr = select(maxfd + 1, &fs, 0, 0, tvp);
#ifdef MC_DEBUG
Dprintf(" sr = %d\n", sr);
#endif
if (sr < 0) {
warning(_("error '%s' in select"), strerror(errno));
return ScalarLogical(0); /* FALSE on select error */
}
if (sr < 1) return ScalarLogical(1); /* TRUE on timeout */
ci = children;
maxfd = 0;
while (ci && ci->pid) { /* pass 1 - count the FDs (in theory not
necessary since that's what select
should have returned) */
if (ci->pfd > 0 && FD_ISSET(ci->pfd, &fs)) maxfd++;
ci = ci -> next;
}
ci = children;
#ifdef MC_DEBUG
Dprintf(" - read select %d children: ", maxfd);
#endif
res = allocVector(INTSXP, maxfd);
res_i = INTEGER(res);
while (ci && ci->pid) { /* pass 2 - fill the array */
if (ci->pfd > 0 && FD_ISSET(ci->pfd, &fs)) (res_i++)[0] = ci->pid;
#ifdef MC_DEBUG
if (ci->pfd > 0 && FD_ISSET(ci->pfd, &fs)) Dprintf("%d ", ci->pid);
#endif
ci = ci -> next;
}
#ifdef MC_DEBUG
Dprintf("\n");
#endif
return res;
}
