/* -----------------------------------------------------------------------------
- * $Id: Select.c,v 1.16 2001/02/28 14:23:55 sewardj Exp $
+ * $Id: Select.c,v 1.22 2002/07/24 03:38:58 sof Exp $
*
- * (c) The GHC Team 1995-1999
+ * (c) The GHC Team 1995-2002
*
* Support for concurrent non-blocking I/O and thread waiting.
*
* ---------------------------------------------------------------------------*/
/* we're outside the realms of POSIX here... */
-#define NON_POSIX_SOURCE
+/* #include "PosixSource.h" */
#include "Rts.h"
#include "Schedule.h"
# include <windows.h>
# endif
+#include <errno.h>
+#include <string.h>
+
/* last timestamp */
nat timestamp = 0;
-/* keep track of the number of ticks since we last called
- * gettimeofday(), to avoid having to call it every time we need
- * a timestamp.
- */
-nat ticks_since_timestamp = 0;
-
/* There's a clever trick here to avoid problems when the time wraps
* around. Since our maximum delay is smaller than 31 bits of ticks
* (it's actually 31 bits of microseconds), we can safely check
int maxfd = -1;
#endif
rtsBool select_succeeded = rtsTrue;
+ rtsBool unblock_all = rtsFalse;
struct timeval tv;
lnat min, ticks;
tv.tv_sec = 0;
tv.tv_usec = 0;
-
+
IF_DEBUG(scheduler,
belch("scheduler: checking for threads blocked on I/O");
if (wait) {
do {
ticks = timestamp = getourtimeofday();
- ticks_since_timestamp = 0;
if (wakeUpSleepingThreads(ticks)) {
return;
}
while ((numFound = select(maxfd+1, &rfd, &wfd, NULL, &tv)) < 0) {
if (errno != EINTR) {
-
- printf("%d\n", errno);
- fflush(stdout);
- perror("select");
+ /* Handle bad file descriptors by unblocking all the
+ waiting threads. Why? Because a thread might have been
+ a bit naughty and closed a file descriptor while another
+ was blocked waiting. This is less-than-good programming
+ practice, but having the RTS as a result fall over isn't
+ acceptable, so we simply unblock all the waiting threads
+ should we see a bad file descriptor & give the threads
+ a chance to clean up their act.
+
+ Note: assume here that threads becoming unblocked
+ will try to read/write the file descriptor before trying
+ to issue a threadWaitRead/threadWaitWrite again (==> an
+ IOError will result for the thread that's got the bad
+ file descriptor.) Hence, there's no danger of a bad
+ file descriptor being repeatedly select()'ed on, so
+ the RTS won't loop.
+ */
+ if ( errno == EBADF ) {
+ unblock_all = rtsTrue;
+ break;
+ } else {
+ fprintf(stderr,"%d\n", errno);
+ fflush(stderr);
+ perror("select");
barf("select failed");
+ }
}
#else /* on mingwin */
while (1) {
*/
if (signals_pending()) {
RELEASE_LOCK(&sched_mutex); /* ToDo: kill */
- start_signal_handlers();
+ startSignalHandlers();
ACQUIRE_LOCK(&sched_mutex);
return; /* still hold the lock */
}
*/
prev = NULL;
- if (select_succeeded) {
+ if (select_succeeded || unblock_all) {
for(tso = blocked_queue_hd; tso != END_TSO_QUEUE; tso = next) {
next = tso->link;
switch (tso->why_blocked) {
case BlockedOnRead:
- ready = FD_ISSET(tso->block_info.fd, &rfd);
+ ready = unblock_all || FD_ISSET(tso->block_info.fd, &rfd);
break;
case BlockedOnWrite:
- ready = FD_ISSET(tso->block_info.fd, &wfd);
+ ready = unblock_all || FD_ISSET(tso->block_info.fd, &wfd);
break;
default:
barf("awaitEvent");