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/*
* rocks/select.c
*
* Sockets API implementation for select.
*
* Copyright (C) 2001 Victor Zandy
* See COPYING for distribution terms.
*/
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/poll.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include "rs.h"
#include "log.h"
/*
Semantics:
Current: Ignore suspended reliable sockets.
Future: Reconnect suspended reliable sockets if no other
descriptors are ready.
*/
static void
choose(int fd, const fd_set *set,
int *rsn, int *sysn, fd_set *rs_set, fd_set *sys_set)
{
/* FIXME: I never understand what this does when I look at it.
Improve the variable names. */
rs_t rs;
assert(FD_ISSET(fd, set));
rs = rs_lookup(fd);
if (rs && RS_SUSPENDED == rs->state) {
FD_SET(fd, rs_set);
if (fd > *rsn)
*rsn = fd;
} else {
FD_SET(fd, sys_set);
if (fd > *sysn)
*sysn = fd;
}
}
/* NN is largest fd set in O, plus 1. N is same wrt S. If FD is set
in S or O, then upon return it is set in S, and N is the largest fd
set in S, plus 1. */
static void
merge_fdset(int *n, fd_set *s, int nn, const fd_set *o)
{
int i;
int max;
max = *n;
for (i = 0; i < nn; i++)
if (FD_ISSET(i, o)) {
FD_SET(i, s);
if (i > max)
max = i;
}
*n = max;
}
/* Assumes native context. Returns 0 if we found and recovered a bad
rock among FDS. */
int
rs_recover_bad_rocks(int n, fd_set *fds)
{
int i;
rs_t rs;
fd_set t;
struct timeval tv;
int rv;
int ret;
ret = -1;
for (i = 0; i < n; i++) {
rs = rs_lookup(i);
if (!rs)
continue;
FD_ZERO(&t);
FD_SET(i, &t);
tv.tv_sec = tv.tv_usec = 0;
rv = select(i+1, &t, NULL, NULL, &tv);
if (0 > rv && errno == EBADF) {
rs_log("select badfd -> begin reconnect");
rs_reconnect(rs, RS_NOBLOCK);
ret = 0;
}
else if (0 > rv)
assert(0); /* Unexpected */
}
return ret;
}
int
rs_select(int n, fd_set *rs, fd_set *ws, fd_set *es, struct timeval *tv)
{
int rv;
int i, rsn, sysn, nn;
fd_set rsrs, rsws, rses; /* suspended rs descriptors */
fd_set sysrs, sysws, syses; /* other descriptors */
fd_set args[3], *rp, *wp, *ep;
int caller_fdsn;
/* Don't waste time if caller just wants timing */
if (n == 0 || (!rs && !ws && !es))
return select(n, rs, ws, es, tv);
retry:
rsn = sysn = 0;
FD_ZERO(&rsrs);
FD_ZERO(&rsws);
FD_ZERO(&rses);
FD_ZERO(&sysrs);
FD_ZERO(&sysws);
FD_ZERO(&syses);
/* Separate suspended rs descriptors */
for (i = 0; i < n; i++) {
if (rs && FD_ISSET(i, rs))
choose(i, rs, &rsn, &sysn, &rsrs, &sysrs);
if (ws && FD_ISSET(i, ws))
choose(i, ws, &rsn, &sysn, &rsws, &sysws);
if (es && FD_ISSET(i, es))
choose(i, es, &rsn, &sysn, &rses, &syses);
}
/* FIXME: Non portable select semantics: on Linux, interrupted
select returns the time not slept. */
if (sysn > 0) {
rp = &args[0];
wp = &args[1];
ep = &args[2];
memcpy(rp, &sysrs, sizeof(fd_set));
memcpy(wp, &sysws, sizeof(fd_set));
memcpy(ep, &syses, sizeof(fd_set));
nn = sysn + 1;
} else {
rp = wp = ep = NULL;
nn = 0;
}
rv = select(nn, rp, wp, ep, tv);
if (0 > rv && errno == EINTR)
goto retry;
/* Bad descriptors can arise following a checkpoint restart */
if (0 > rv && errno == EBADF) {
int n = 0;
fd_set s;
rs_log("Select came back with bad fds\n");
FD_ZERO(&s);
if (rp)
merge_fdset(&n, &s, nn, rp);
if (wp)
merge_fdset(&n, &s, nn, wp);
if (ep)
merge_fdset(&n, &s, nn, ep);
assert(0); /* FIXME: figure out whether reconnect
should block */
if (!rs_recover_bad_rocks(n, &s))
goto retry;
/* Otherwise, the bad fd is the application's problem */
}
/* Copy results to caller. Since not every caller passes in a
whole fd_set, do a minimal copy. */
caller_fdsn = n / 8;
if (n % 8)
++caller_fdsn;
if (rs && rp)
memcpy(rs, rp, caller_fdsn);
if (ws && wp)
memcpy(ws, wp, caller_fdsn);
if (es && ep)
memcpy(es, ep, caller_fdsn);
return rv;
}
int
rs_poll(struct pollfd *ufds, unsigned int nfds, int timeout)
{
assert(0);
return 0;
}
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