Use message-passing to implement throwTo in the RTS

This replaces some complicated locking schemes with message-passing
in the implementation of throwTo. The benefits are

 - previously it was impossible to guarantee that a throwTo from
   a thread running on one CPU to a thread running on another CPU
   would be noticed, and we had to rely on the GC to pick up these
   forgotten exceptions. This no longer happens.

 - the locking regime is simpler (though the code is about the same
   size)

 - threads can be unblocked from a blocked_exceptions queue without
   having to traverse the whole queue now.  It's a rare case, but
   replaces an O(n) operation with an O(1).

 - generally we move in the direction of sharing less between
   Capabilities (aka HECs), which will become important with other
   changes we have planned.

Also in this patch I replaced several STM-specific closure types with
a generic MUT_PRIM closure type, which allowed a lot of code in the GC
and other places to go away, hence the line-count reduction.  The
message-passing changes resulted in about a net zero line-count
difference.

1 files changed, 0 insertions, 28 deletions

diff --git a/rts/Schedule.h b/rts/Schedule.h
index af322d804f..76138b68f3 100644
--- a/rts/Schedule.h
+++ b/rts/Schedule.h
@@ -105,7 +105,6 @@ extern Mutex sched_mutex;
 void interruptStgRts (void);
 
 void resurrectThreads (StgTSO *);
-void performPendingThrowTos (StgTSO *);
 
 /* -----------------------------------------------------------------------------
  * Some convenient macros/inline functions...
@@ -179,25 +178,6 @@ appendToBlockedQueue(StgTSO *tso)
 }
 #endif
 
-#if defined(THREADED_RTS)
-// Assumes: my_cap is owned by the current Task.  We hold
-// other_cap->lock, but we do not necessarily own other_cap; another
-// Task may be running on it.
-INLINE_HEADER void
-appendToWakeupQueue (Capability *my_cap, Capability *other_cap, StgTSO *tso)
-{
-    ASSERT(tso->_link == END_TSO_QUEUE);
-    if (other_cap->wakeup_queue_hd == END_TSO_QUEUE) {
-	other_cap->wakeup_queue_hd = tso;
-    } else {
-        // my_cap is passed to setTSOLink() because it may need to
-        // write to the mutable list.
-	setTSOLink(my_cap, other_cap->wakeup_queue_tl, tso);
-    }
-    other_cap->wakeup_queue_tl = tso;
-}
-#endif
-
 /* Check whether various thread queues are empty
  */
 INLINE_HEADER rtsBool
@@ -212,14 +192,6 @@ emptyRunQueue(Capability *cap)
     return emptyQueue(cap->run_queue_hd);
 }
 
-#if defined(THREADED_RTS)
-INLINE_HEADER rtsBool
-emptyWakeupQueue(Capability *cap)
-{
-    return emptyQueue(cap->wakeup_queue_hd);
-}
-#endif
-
 #if !defined(THREADED_RTS)
 #define EMPTY_BLOCKED_QUEUE()  (emptyQueue(blocked_queue_hd))
 #define EMPTY_SLEEPING_QUEUE() (emptyQueue(sleeping_queue))