/* -----------------------------------------------------------------------------
- * $Id: Select.c,v 1.16 2001/02/28 14:23:55 sewardj 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 "RtsUtils.h"
#include "RtsFlags.h"
+#include "Timer.h"
#include "Itimer.h"
#include "Signals.h"
+#include "Capability.h"
# ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
# include <sys/time.h>
# endif
-# ifdef mingw32_TARGET_OS
-# include <windows.h>
-# endif
+#include <errno.h>
+#include <string.h>
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
/* 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
sleeping_queue = tso->link;
tso->why_blocked = NotBlocked;
tso->link = END_TSO_QUEUE;
- IF_DEBUG(scheduler,belch("Waking up sleeping thread %d\n", tso->id));
+ IF_DEBUG(scheduler,debugBelch("Waking up sleeping thread %d\n", tso->id));
PUSH_ON_RUN_QUEUE(tso);
flag = rtsTrue;
}
StgTSO *tso, *prev, *next;
rtsBool ready;
fd_set rfd,wfd;
-#ifndef mingw32_TARGET_OS
int numFound;
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");
+ debugBelch("scheduler: checking for threads blocked on I/O");
if (wait) {
- belch(" (waiting)");
+ debugBelch(" (waiting)");
}
- belch("\n");
+ debugBelch("\n");
);
/* loop until we've woken up some threads. This loop is needed
do {
ticks = timestamp = getourtimeofday();
- ticks_since_timestamp = 0;
if (wakeUpSleepingThreads(ticks)) {
return;
}
min = 0x7ffffff;
}
-#ifndef mingw32_TARGET_OS
/*
* Collect all of the fd's that we're interested in
*/
}
}
- /* Release the scheduler lock while we do the poll.
- * this means that someone might muck with the blocked_queue
- * while we do this, but it shouldn't matter:
- *
- * - another task might poll for I/O and remove one
- * or more threads from the blocked_queue.
- * - more I/O threads may be added to blocked_queue.
- * - more delayed threads may be added to blocked_queue. We'll
- * just subtract delta from their delays after the poll.
- *
- * I believe none of these cases lead to trouble --SDM.
- */
- RELEASE_LOCK(&sched_mutex);
-
/* Check for any interesting events */
tv.tv_sec = min / 1000000;
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 {
+ perror("select");
barf("select failed");
+ }
}
-#else /* on mingwin */
- while (1) {
- Sleep(0); /* don't busy wait */
-#endif /* mingw32_TARGET_OS */
- ACQUIRE_LOCK(&sched_mutex);
-#ifndef mingw32_TARGET_OS
/* We got a signal; could be one of ours. If so, we need
* to start up the signal handler straight away, otherwise
* we could block for a long time before the signal is
* serviced.
*/
+#if defined(RTS_USER_SIGNALS)
if (signals_pending()) {
- RELEASE_LOCK(&sched_mutex); /* ToDo: kill */
- start_signal_handlers();
- ACQUIRE_LOCK(&sched_mutex);
+ startSignalHandlers();
return; /* still hold the lock */
}
#endif
if (run_queue_hd != END_TSO_QUEUE) {
return; /* still hold the lock */
}
-
- RELEASE_LOCK(&sched_mutex);
}
- ACQUIRE_LOCK(&sched_mutex);
-
/* Step through the waiting queue, unblocking every thread that now has
* a file descriptor in a ready state.
*/
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");
}
if (ready) {
- IF_DEBUG(scheduler,belch("Waking up blocked thread %d\n", tso->id));
+ IF_DEBUG(scheduler,debugBelch("Waking up blocked thread %d\n", tso->id));
tso->why_blocked = NotBlocked;
tso->link = END_TSO_QUEUE;
PUSH_ON_RUN_QUEUE(tso);
blocked_queue_tl = prev;
}
}
-
+
} while (wait && !interrupted && run_queue_hd == END_TSO_QUEUE);
}