[Oberon] precise specification of single remaining difficulty

[Søren Renner]

MODULE srThreadDemo;
IMPORT srBase, AosActive, DebugLog;

TYPE thread=OBJECT
VAR
	I: INTEGER;
	
PROCEDURE&init(i:INTEGER);
BEGIN
	I:=i;
END init;
	
BEGIN{ACTIVE, PRIORITY(AosActive.Normal)}
	REPEAT
		BEGIN{EXCLUSIVE}	
			AWAIT(flag[I]);
			INC(threadsdone);
			flag[I]:=FALSE;
		END;
		DebugLog.Int(threadsdone,4);	
		DebugLog.String("threads done");
	UNTIL FALSE;
END thread;

VAR
	threads: ARRAY 10 OF thread;
	flag: ARRAY 10 OF BOOLEAN;
	gothreads: BOOLEAN;
	i: INTEGER;
	threadsdone: INTEGER;

PROCEDURE go*;
VAR
     i:INTEGER;
BEGIN
	BEGIN{EXCLUSIVE}	
		threadsdone:=0;
		FOR i := 0 TO 9 DO
			flag[i]:=TRUE
		END;
		DebugLog.String("go go little threads. which thread will win? . . .");
		AWAIT(threadsdone=10)
	END;
	DebugLog.String("well, so much for those threads i guess"); (* NEVER
REACHED! *)
END go;

PROCEDURE loadmodule*;
END loadmodule;

BEGIN
	BEGIN{EXCLUSIVE}	
		gothreads:=FALSE
	END;
	FOR i := 0 TO 9 DO
		NEW(threads[i],i);
		DebugLog.String("sprawning thread "); DebugLog.Int(i,4); DebugLog.Ln;
	END;
	go;
END srThreadDemo.

srThreadDemo.go:

DebugLog output:

P1.218 srThreadDemo.$$[208]> sprawning thread

P1.218 srThreadDemo.$$[223]>    0

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    1

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    2

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    3

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    4

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    5

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    6

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    7

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    8

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.$$[208]> sprawning thread

P0.218 srThreadDemo.$$[223]>    9

P0.218 srThreadDemo.$$[228]>

P0.218 srThreadDemo.go[538]> go go little threads. which thread will win? . . .

P1.219 srThreadDemo.thread. at Body[419]>    1

P1.219 srThreadDemo.thread. at Body[431]> threads done

P1.220 srThreadDemo.thread. at Body[419]>    2

P1.220 srThreadDemo.thread. at Body[431]> threads done

P1.221 srThreadDemo.thread. at Body[419]>    3

P1.221 srThreadDemo.thread. at Body[431]> threads done

P1.222 srThreadDemo.thread. at Body[419]>    4

P1.222 srThreadDemo.thread. at Body[431]> threads done

P1.223 srThreadDemo.thread. at Body[419]>    5

P1.223 srThreadDemo.thread. at Body[431]> threads done

P1.224 srThreadDemo.thread. at Body[419]>    6

P1.224 srThreadDemo.thread. at Body[431]> threads done

P1.225 srThreadDemo.thread. at Body[419]>    7

P1.225 srThreadDemo.thread. at Body[431]> threads done

P1.226 srThreadDemo.thread. at Body[419]>    8

P1.226 srThreadDemo.thread. at Body[431]> threads done

P1.227 srThreadDemo.thread. at Body[419]>    9

P1.227 srThreadDemo.thread. at Body[431]> threads done

P1.228 srThreadDemo.thread. at Body[419]>   10

P1.228 srThreadDemo.thread. at Body[431]> threads done

Why is AWAIT(threadsdone=10) never triggered?