[project @ 2004-03-13 00:56:45 by sof]
[ghc-hetmet.git] / ghc / rts / Schedule.c
index 0e14c6e..262e4c4 100644 (file)
@@ -1,5 +1,5 @@
 /* ---------------------------------------------------------------------------
- * $Id: Schedule.c,v 1.192 2004/02/27 16:16:31 simonmar Exp $
+ * $Id: Schedule.c,v 1.194 2004/03/13 00:56:45 sof Exp $
  *
  * (c) The GHC Team, 1998-2003
  *
@@ -259,6 +259,7 @@ static void
 taskStart(void)
 {
   ACQUIRE_LOCK(&sched_mutex);
+  startingWorkerThread = rtsFalse;
   schedule(NULL,NULL);
   RELEASE_LOCK(&sched_mutex);
 }
@@ -431,92 +432,6 @@ schedule( StgMainThread *mainThread USED_WHEN_RTS_SUPPORTS_THREADS,
 #endif
     }
 
-    //
-    // Go through the list of main threads and wake up any
-    // clients whose computations have finished.  ToDo: this
-    // should be done more efficiently without a linear scan
-    // of the main threads list, somehow...
-    //
-#if defined(RTS_SUPPORTS_THREADS)
-    { 
-       StgMainThread *m, **prev;
-       prev = &main_threads;
-       for (m = main_threads; m != NULL; prev = &m->link, m = m->link) {
-           if (m->tso->what_next == ThreadComplete
-               || m->tso->what_next == ThreadKilled) {
-               if (m == mainThread) {
-                   if (m->tso->what_next == ThreadComplete) {
-                       if (m->ret) {
-                           // NOTE: return val is tso->sp[1]
-                           // (see StgStartup.hc)
-                           *(m->ret) = (StgClosure *)m->tso->sp[1]; 
-                       }
-                       m->stat = Success;
-                   } else {
-                       if (m->ret) {
-                           *(m->ret) = NULL;
-                       }
-                       if (was_interrupted) {
-                           m->stat = Interrupted;
-                       } else {
-                           m->stat = Killed;
-                       }
-                   }
-                   *prev = m->link;
-#ifdef DEBUG
-                   removeThreadLabel((StgWord)m->tso->id);
-#endif
-                   releaseCapability(cap);
-                   return;
-               } else {
-                   // The current OS thread can not handle the fact that
-                   // the Haskell thread "m" has ended.  "m" is bound;
-                   // the scheduler loop in its bound OS thread has to
-                   // return, so let's pass the capability directly to
-                   // that thread.
-                   passCapability(&m->bound_thread_cond);
-                   continue;
-               }
-           }
-       }
-    }
-    
-#else /* not threaded */
-
-# if defined(PAR)
-    /* in GUM do this only on the Main PE */
-    if (IAmMainThread)
-# endif
-    /* If our main thread has finished or been killed, return.
-     */
-    {
-      StgMainThread *m = main_threads;
-      if (m->tso->what_next == ThreadComplete
-         || m->tso->what_next == ThreadKilled) {
-#ifdef DEBUG
-       removeThreadLabel((StgWord)m->tso->id);
-#endif
-       main_threads = main_threads->link;
-       if (m->tso->what_next == ThreadComplete) {
-           // We finished successfully, fill in the return value
-           // NOTE: return val is tso->sp[1] (see StgStartup.hc)
-           if (m->ret) { *(m->ret) = (StgClosure *)m->tso->sp[1]; };
-           m->stat = Success;
-           return;
-       } else {
-         if (m->ret) { *(m->ret) = NULL; };
-         if (was_interrupted) {
-           m->stat = Interrupted;
-         } else {
-           m->stat = Killed;
-         }
-         return;
-       }
-      }
-    }
-#endif
-
-
 #if defined(RTS_USER_SIGNALS)
     // check for signals each time around the scheduler
     if (signals_pending()) {
@@ -605,11 +520,9 @@ schedule( StgMainThread *mainThread USED_WHEN_RTS_SUPPORTS_THREADS,
            m = main_threads;
            switch (m->tso->why_blocked) {
            case BlockedOnBlackHole:
-               raiseAsync(m->tso, (StgClosure *)NonTermination_closure);
-               break;
            case BlockedOnException:
            case BlockedOnMVar:
-               raiseAsync(m->tso, (StgClosure *)Deadlock_closure);
+               raiseAsync(m->tso, (StgClosure *)NonTermination_closure);
                break;
            default:
                barf("deadlock: main thread blocked in a strange way");
@@ -915,12 +828,7 @@ schedule( StgMainThread *mainThread USED_WHEN_RTS_SUPPORTS_THREADS,
 
 #ifdef THREADED_RTS
     {
-      StgMainThread *m;
-      for(m = main_threads; m; m = m->link)
-      {
-       if(m->tso == t)
-         break;
-      }
+      StgMainThread *m = t->main;
       
       if(m)
       {
@@ -1144,7 +1052,6 @@ run_thread:
        */
       threadPaused(t);
       { 
-       StgMainThread *m;
        /* enlarge the stack */
        StgTSO *new_t = threadStackOverflow(t);
        
@@ -1152,10 +1059,8 @@ run_thread:
         * main thread stack.  It better not be on any other queues...
         * (it shouldn't be).
         */
-       for (m = main_threads; m != NULL; m = m->link) {
-         if (m->tso == t) {
-           m->tso = new_t;
-         }
+       if (t->main != NULL) {
+           t->main->tso = new_t;
        }
        threadPaused(new_t);
        PUSH_ON_RUN_QUEUE(new_t);
@@ -1318,8 +1223,74 @@ run_thread:
          !RtsFlags.ParFlags.ParStats.Suppressed) 
        DumpEndEvent(CURRENT_PROC, t, rtsFalse /* not mandatory */);
 #endif
+
+      //
+      // Check whether the thread that just completed was a main
+      // thread, and if so return with the result.  
+      //
+      // There is an assumption here that all thread completion goes
+      // through this point; we need to make sure that if a thread
+      // ends up in the ThreadKilled state, that it stays on the run
+      // queue so it can be dealt with here.
+      //
+      if (
+#if defined(RTS_SUPPORTS_THREADS)
+         mainThread != NULL
+#else
+         mainThread->tso == t
+#endif
+         )
+      {
+         // We are a bound thread: this must be our thread that just
+         // completed.
+         ASSERT(mainThread->tso == t);
+
+         if (t->what_next == ThreadComplete) {
+             if (mainThread->ret) {
+                 // NOTE: return val is tso->sp[1] (see StgStartup.hc)
+                 *(mainThread->ret) = (StgClosure *)mainThread->tso->sp[1]; 
+             }
+             mainThread->stat = Success;
+         } else {
+             if (mainThread->ret) {
+                 *(mainThread->ret) = NULL;
+             }
+             if (was_interrupted) {
+                 mainThread->stat = Interrupted;
+             } else {
+                 mainThread->stat = Killed;
+             }
+         }
+#ifdef DEBUG
+         removeThreadLabel((StgWord)mainThread->tso->id);
+#endif
+         if (mainThread->prev == NULL) {
+             main_threads = mainThread->link;
+         } else {
+             mainThread->prev->link = mainThread->link;
+         }
+         if (mainThread->link != NULL) {
+             mainThread->link->prev = NULL;
+         }
+         releaseCapability(cap);
+         return;
+      }
+
+#ifdef RTS_SUPPORTS_THREADS
+      ASSERT(t->main == NULL);
+#else
+      if (t->main != NULL) {
+         // Must be a main thread that is not the topmost one.  Leave
+         // it on the run queue until the stack has unwound to the
+         // point where we can deal with this.  Leaving it on the run
+         // queue also ensures that the garbage collector knows about
+         // this thread and its return value (it gets dropped from the
+         // all_threads list so there's no other way to find it).
+         APPEND_TO_RUN_QUEUE(t);
+      }
+#endif
       break;
-      
+
     default:
       barf("schedule: invalid thread return code %d", (int)ret);
     }
@@ -1400,12 +1371,7 @@ StgBool
 isThreadBound(StgTSO* tso USED_IN_THREADED_RTS)
 {
 #ifdef THREADED_RTS
-  StgMainThread *m;
-  for(m = main_threads; m; m = m->link)
-  {
-    if(m->tso == tso)
-      return rtsTrue;
-  }
+  return (tso->main != NULL);
 #endif
   return rtsFalse;
 }
@@ -1414,13 +1380,22 @@ isThreadBound(StgTSO* tso USED_IN_THREADED_RTS)
  * Singleton fork(). Do not copy any running threads.
  * ------------------------------------------------------------------------- */
 
+#ifndef mingw32_TARGET_OS
+#define FORKPROCESS_PRIMOP_SUPPORTED
+#endif
+
+#ifdef FORKPROCESS_PRIMOP_SUPPORTED
 static void 
 deleteThreadImmediately(StgTSO *tso);
-
+#endif
 StgInt
-forkProcess(HsStablePtr *entry)
+forkProcess(HsStablePtr *entry
+#ifndef FORKPROCESS_PRIMOP_SUPPORTED
+           STG_UNUSED
+#endif
+           )
 {
-#ifndef mingw32_TARGET_OS
+#ifdef FORKPROCESS_PRIMOP_SUPPORTED
   pid_t pid;
   StgTSO* t,*next;
   StgMainThread *m;
@@ -1454,17 +1429,17 @@ forkProcess(HsStablePtr *entry)
       // wipe the main thread list
     while((m = main_threads) != NULL) {
       main_threads = m->link;
-#ifdef THREADED_RTS
+# ifdef THREADED_RTS
       closeCondition(&m->bound_thread_cond);
-#endif
+# endif
       stgFree(m);
     }
     
-#ifdef RTS_SUPPORTS_THREADS
+# ifdef RTS_SUPPORTS_THREADS
     resetTaskManagerAfterFork();      // tell startTask() and friends that
     startingWorkerThread = rtsFalse;  // we have no worker threads any more
     resetWorkerWakeupPipeAfterFork();
-#endif
+# endif
     
     rc = rts_evalStableIO(entry, NULL);  // run the action
     rts_checkSchedStatus("forkProcess",rc);
@@ -1474,10 +1449,10 @@ forkProcess(HsStablePtr *entry)
     hs_exit();                      // clean up and exit
     stg_exit(0);
   }
-#else /* mingw32 */
-  barf("forkProcess#: primop not implemented for mingw32, sorry!\n");
+#else /* !FORKPROCESS_PRIMOP_SUPPORTED */
+  barf("forkProcess#: primop not supported, sorry!\n");
   return -1;
-#endif /* mingw32 */
+#endif
 }
 
 /* ---------------------------------------------------------------------------
@@ -1550,17 +1525,12 @@ suspendThread( StgRegTable *reg,
   cap->r.rCurrentTSO->link = suspended_ccalling_threads;
   suspended_ccalling_threads = cap->r.rCurrentTSO;
 
-#if defined(RTS_SUPPORTS_THREADS)
-  if(cap->r.rCurrentTSO->blocked_exceptions == NULL)
-  {
+  if(cap->r.rCurrentTSO->blocked_exceptions == NULL)  {
       cap->r.rCurrentTSO->why_blocked = BlockedOnCCall;
       cap->r.rCurrentTSO->blocked_exceptions = END_TSO_QUEUE;
-  }
-  else
-  {
+  } else {
       cap->r.rCurrentTSO->why_blocked = BlockedOnCCall_NoUnblockExc;
   }
-#endif
 
   /* Use the thread ID as the token; it should be unique */
   tok = cap->r.rCurrentTSO->id;
@@ -1616,13 +1586,10 @@ resumeThread( StgInt tok,
   }
   tso->link = END_TSO_QUEUE;
   
-#if defined(RTS_SUPPORTS_THREADS)
-  if(tso->why_blocked == BlockedOnCCall)
-  {
+  if(tso->why_blocked == BlockedOnCCall) {
       awakenBlockedQueueNoLock(tso->blocked_exceptions);
       tso->blocked_exceptions = NULL;
   }
-#endif
   
   /* Reset blocking status */
   tso->why_blocked  = NotBlocked;
@@ -1751,6 +1718,7 @@ createThread(nat size)
   tso->blocked_exceptions = NULL;
 
   tso->saved_errno = 0;
+  tso->main = NULL;
   
   tso->stack_size   = stack_size;
   tso->max_stack_size = round_to_mblocks(RtsFlags.GcFlags.maxStkSize) 
@@ -1970,8 +1938,16 @@ scheduleWaitThread(StgTSO* tso, /*[out]*/HaskellObj* ret,
 
     m = stgMallocBytes(sizeof(StgMainThread), "waitThread");
     m->tso = tso;
+    tso->main = m;
     m->ret = ret;
     m->stat = NoStatus;
+    m->link = main_threads;
+    m->prev = NULL;
+    if (main_threads != NULL) {
+       main_threads->prev = m;
+    }
+    main_threads = m;
+
 #if defined(RTS_SUPPORTS_THREADS)
     // Allocating a new condition for each thread is expensive, so we
     // cache one.  This is a pretty feeble hack, but it helps speed up
@@ -1995,9 +1971,6 @@ scheduleWaitThread(StgTSO* tso, /*[out]*/HaskellObj* ret,
     */
     IF_DEBUG(scheduler, sched_belch("waiting for thread (%d)", tso->id));
     
-    m->link = main_threads;
-    main_threads = m;
-    
     PUSH_ON_RUN_QUEUE(tso);
     // NB. Don't call THREAD_RUNNABLE() here, because the thread is
     // bound and only runnable by *this* OS thread, so waking up other
@@ -2201,25 +2174,6 @@ GetRoots( evac_fn evac )
   // mark the signal handlers (signals should be already blocked)
   markSignalHandlers(evac);
 #endif
-
-  // main threads which have completed need to be retained until they
-  // are dealt with in the main scheduler loop.  They won't be
-  // retained any other way: the GC will drop them from the
-  // all_threads list, so we have to be careful to treat them as roots
-  // here.
-  { 
-      StgMainThread *m;
-      for (m = main_threads; m != NULL; m = m->link) {
-         switch (m->tso->what_next) {
-         case ThreadComplete:
-         case ThreadKilled:
-             evac((StgClosure **)&m->tso);
-             break;
-         default:
-             break;
-         }
-      }
-  }
 }
 
 /* -----------------------------------------------------------------------------
@@ -2635,7 +2589,6 @@ awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node)
 
 #else   /* !GRAN && !PAR */
 
-#ifdef RTS_SUPPORTS_THREADS
 void
 awakenBlockedQueueNoLock(StgTSO *tso)
 {
@@ -2643,7 +2596,6 @@ awakenBlockedQueueNoLock(StgTSO *tso)
     tso = unblockOneLocked(tso);
   }
 }
-#endif
 
 void
 awakenBlockedQueue(StgTSO *tso)
@@ -2988,6 +2940,7 @@ deleteThread(StgTSO *tso)
   raiseAsync(tso,NULL);
 }
 
+#ifdef FORKPROCESS_PRIMOP_SUPPORTED
 static void 
 deleteThreadImmediately(StgTSO *tso)
 { // for forkProcess only:
@@ -2996,13 +2949,15 @@ deleteThreadImmediately(StgTSO *tso)
   if (tso->what_next == ThreadComplete || tso->what_next == ThreadKilled) {
       return;
   }
-#if defined(RTS_SUPPORTS_THREADS)
-  if (tso->why_blocked != BlockedOnCCall
-      && tso->why_blocked != BlockedOnCCall_NoUnblockExc)
-#endif
+
+  if (tso->why_blocked != BlockedOnCCall &&
+      tso->why_blocked != BlockedOnCCall_NoUnblockExc) {
     unblockThread(tso);
+  }
+
   tso->what_next = ThreadKilled;
 }
+#endif
 
 void
 raiseAsyncWithLock(StgTSO *tso, StgClosure *exception)
@@ -3334,14 +3289,12 @@ printThreadBlockage(StgTSO *tso)
            tso->block_info.closure, info_type(tso->block_info.closure));
     break;
 #endif
-#if defined(RTS_SUPPORTS_THREADS)
   case BlockedOnCCall:
     fprintf(stderr,"is blocked on an external call");
     break;
   case BlockedOnCCall_NoUnblockExc:
     fprintf(stderr,"is blocked on an external call (exceptions were already blocked)");
     break;
-#endif
   default:
     barf("printThreadBlockage: strange tso->why_blocked: %d for TSO %d (%d)",
         tso->why_blocked, tso->id, tso);