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/* asyn_wait() - wait for asynch operations Author: Kees J. Bot
* 7 Jul 1997
*/
#include "asyn.h"
#include <time.h>
#ifdef DEBUG
#include <stdio.h>
#endif
#define TBOUND_MIN 1
#define TBOUND_MAX 16
int asyn_wait(asynchio_t *asyn, int flags, struct timeval *to)
/* Wait for one or more nonblocking operations to return a result. */
{
int r;
static struct timeval zero_time;
struct timeval t;
static time_t tbound= TBOUND_MIN;
/* Are there more things to do before we can block? */
if (asyn->asyn_more > 0) { asyn->asyn_more= 0; return 0; }
if (flags & ASYN_NONBLOCK) {
/* Don't block by using a zero second timeout. */
to= &zero_time;
} else
if (to != nil) {
/* asyn_wait() uses an absolute time. */
if (to->tv_usec >= 1000000L) {
to->tv_sec+= to->tv_usec / 1000000L;
to->tv_usec%= 1000000L;
}
(void) gettimeofday(&t, nil);
if (t.tv_sec > to->tv_sec || (t.tv_sec == to->tv_sec
&& t.tv_usec >= to->tv_usec)) {
to= &zero_time;
} else {
t.tv_sec= to->tv_sec - t.tv_sec;
t.tv_usec= to->tv_usec - t.tv_usec;
if (t.tv_usec < 0) {
t.tv_sec--;
t.tv_usec+= 1000000L;
}
to= &t;
}
/* Don't sleep too long, we don't trust select(). */
if (to->tv_sec > tbound) goto bound;
} else {
bound:
/* No timeout? Don't hang in (buggy?) select() forever. */
to= &t;
t.tv_sec= tbound;
t.tv_usec= 0;
}
#ifdef DEBUG
{
int op;
fprintf(stderr, "select: ");
for (op= 0; op < SEL_NR; op++) {
fd_set *fdsetp= &asyn->asyn_fdset[op];
int fd;
for (fd= 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, fdsetp)) {
asyn->asyn_afd[fd].afd_state[op]=
PENDING;
fprintf(stderr, "%d%c", fd, "rwx"[op]);
}
}
}
fflush(stderr);
}
#endif
r= select(FD_SETSIZE, &asyn->asyn_fdset[SEL_READ],
&asyn->asyn_fdset[SEL_WRITE],
&asyn->asyn_fdset[SEL_EXCEPT], to);
#ifdef DEBUG
fprintf(stderr, " (%d) ", r);
#endif
if (r > 0) {
/* An event occurred on one or more file descriptors. */
int op;
for (op= 0; op < SEL_NR; op++) {
fd_set *fdsetp= &asyn->asyn_fdset[op];
int fd;
for (fd= 0; fd < FD_SETSIZE; fd++) {
if (FD_ISSET(fd, fdsetp)) {
asyn->asyn_afd[fd].afd_state[op]=
PENDING;
#ifdef DEBUG
fprintf(stderr, "%d%c", fd, "rwx"[op]);
#endif
}
}
}
tbound= TBOUND_MIN;
} else
if (r == 0) {
/* If nothing happened then let the time boundary slip a bit. */
if (tbound < TBOUND_MAX) tbound <<= 1;
}
#ifdef DEBUG
fputc('\n', stderr);
#endif
FD_ZERO(&asyn->asyn_fdset[SEL_READ]);
FD_ZERO(&asyn->asyn_fdset[SEL_WRITE]);
FD_ZERO(&asyn->asyn_fdset[SEL_EXCEPT]);
return r == 0 ? (errno= EINTR, -1) : r;
}
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