[project @ 2004-11-10 03:20:31 by wolfgang]

[ghc-hetmet.git] / ghc / rts / Select.c

diff --git a/ghc/rts/Select.c b/ghc/rts/Select.c
index a2c990e..418e48c 100644 (file)
--- a/ghc/rts/Select.c
+++ b/ghc/rts/Select.c
@@ -1,5 +1,4 @@
 /* -----------------------------------------------------------------------------
- * $Id: Select.c,v 1.21 2002/07/17 09:21:51 simonmar Exp $
  *
  * (c) The GHC Team 1995-2002
  *
@@ -7,6 +6,7 @@
  *
  * ---------------------------------------------------------------------------*/
 
+
 /* we're outside the realms of POSIX here... */
 /* #include "PosixSource.h" */
 
@@ -14,8 +14,10 @@
 #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>
@@ -25,13 +27,13 @@
 #  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;
 
@@ -58,7 +60,7 @@ wakeUpSleepingThreads(nat ticks)
        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;
     }
@@ -84,13 +86,10 @@ awaitEvent(rtsBool wait)
     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;
-    static rtsBool prev_unblocked_all = rtsFalse;
     struct timeval tv;
     lnat min, ticks;
 
@@ -98,11 +97,11 @@ awaitEvent(rtsBool wait)
     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
@@ -126,7 +125,6 @@ awaitEvent(rtsBool wait)
          min = 0x7ffffff;
       }
 
-#ifndef mingw32_TARGET_OS
       /* 
        * Collect all of the fd's that we're interested in
        */
@@ -158,20 +156,6 @@ awaitEvent(rtsBool wait)
        }
       }
 
-      /* 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;
@@ -188,38 +172,31 @@ awaitEvent(rtsBool wait)
               should we see a bad file descriptor & give the threads
               a chance to clean up their act. 
               
-              To avoid getting stuck in a loop, repeated EBADF failures
-              are 'handled' through barfing.
+              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 && !prev_unblocked_all) {
+           if ( errno == EBADF ) {
              unblock_all = rtsTrue;
-             prev_unblocked_all = rtsTrue;
              break;
            } else {
-             fprintf(stderr,"%d\n", errno);
-             fflush(stderr);
              perror("select");
              barf("select failed");
            }
          }
-#else /* on mingwin */
-      while (1) {
-         Sleep(0); /* don't busy wait */
-#endif /* mingw32_TARGET_OS */
-         ACQUIRE_LOCK(&sched_mutex);
-
-         prev_unblocked_all = rtsFalse;
 
-#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 */
              startSignalHandlers();
-             ACQUIRE_LOCK(&sched_mutex);
              return; /* still hold the lock */
          }
 #endif
@@ -240,12 +217,8 @@ awaitEvent(rtsBool wait)
          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.
        */
@@ -266,7 +239,7 @@ awaitEvent(rtsBool wait)
              }
       
              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);
@@ -286,6 +259,6 @@ awaitEvent(rtsBool wait)
              blocked_queue_tl = prev;
          }
       }
-
+      
     } while (wait && !interrupted && run_queue_hd == END_TSO_QUEUE);
 }