migrated some primitives from Processor to System.

Fixed a bug in manipulating moo->sem_io_wait_count.
Experimenting to add a shortcut exception handling syntax

moo/kernel/Process.moo

@@ -239,6 +239,54 @@ method(#class,#abstract) xxx. => method(#class) xxx { self subclassResponsibilit
 		^x
 	}
 
+	method _waitWithTimeout: seconds
+	{
+		| s r |
+
+		## create an internal semaphore for timeout notification.
+		s := Semaphore _new.
+		if (s isError) { ^s }.
+
+		## grant the partial membership to the internal semaphore.
+		## it's partial because it's not added to self.semarr.
+		##s _group: self. 
+		if ((r := (self addSemaphore: s)) isError) { ^r }.
+
+		## arrange the processor to notify upon timeout.
+		if ((r := (System _signal: s after: seconds)) isError) { ^r }.
+
+		if ((r := self _wait) isError) 
+		{
+			System _unsignal: s.
+			^r.
+		}.
+
+		## if the internal semaphore has been signaled, 
+		## arrange to return nil to indicate timeout.
+		if (r == s) { r := nil }
+		elsif (r signalAction notNil) { r signalAction value: r }.
+
+		## nullify the membership
+		self _removeSemaphore: s.
+
+		## cancel the notification arrangement in case it didn't time out.
+		System _unsignal: s.
+
+		^r.
+	}
+
+	method waitWithTimeout: seconds
+	{
+		| r |
+		r := self _waitWithTimeout: seconds.
+		if (r isError)  
+		{
+			Exception signal: 'Error has occurred...' error: r.
+		}.
+		^r
+	}
+
+(*
 	method waitWithTimeout: seconds
 	{
 		| s r |
@@ -254,8 +302,13 @@ method(#class,#abstract) xxx. => method(#class) xxx { self subclassResponsibilit
 		## arrange the processor to notify upon timeout.
 		System signal: s after: seconds.
 
-		## wait on the semaphore group.
-		r := self wait.
+		[
+			## wait on the semaphore group.
+			r := self wait.
+		] on: Exception do: [:ex |
+			System _unsignal: s.
+			ex throw
+		].
 
 		## if the internal semaphore has been signaled, 
 		## arrange to return nil to indicate timeout.
@@ -270,6 +323,7 @@ method(#class,#abstract) xxx. => method(#class) xxx { self subclassResponsibilit
 
 		^r.
 	} 
+*)
 }
 
 class SemaphoreHeap(Object)
@@ -471,10 +525,4 @@ class(#final,#limited) ProcessScheduler(Object)
 			].
 		*)
 	}
-
-	method return: object to: context
-	{
-		<primitive: #_processor_return_to>
-		self primitiveFailed.
-	}
 }