Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!decwrl!pa.dec.com!src.dec.com!Thomas Roemke <modula-3@uni-paderborn.de>
From: modula-3@uni-paderborn.de (Thomas Roemke)
Newsgroups: comp.lang.modula3
Subject: Re: help wanted with Thread.Alert
Message-ID: <9104041502.AA04492@thor.uni-paderborn.de>
Date: 4 Apr 91 15:19:47 GMT
Lines: 63
To: m3
Cc: nr@dynamic.princeton.edu
X-Mailer: ELM [version 2.3 PL11]


nr@@Princeton.EDU (Norman Ramsey) writes:

>I don't understand why my thread isn't raising Thread.Alerted in the
>following program:
>[..] see below.

Thread.Alert(t) marks t as alerted, nothing else. No
exception is raised, neither in the calling nor in the
marked thread. If you want to have that behaviour, you've
to raise an exception explicitly, e.g. 


  MODULE Alert EXPORTS Main;
  IMPORT Rd, Wr, Thread, Fmt;
  FROM Stdio IMPORT stdin, stdout;
  
  PROCEDURE Copy(cl:Thread.Closure):REFANY RAISES {} =
  VAR result := NEW(REF INTEGER);
  BEGIN
    result^ := 0;
    TRY
      LOOP
        IF Thread.TestAlert() THEN 
	  EXIT; (* or RAISE Thread.Alerted *) 
	END;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	WITH line = Rd.GetLine(stdin) DO
  	INC(result^);
          Wr.PutText(stdout,Fmt.F("line is `%s\'\n",line));
        END;
      END;
    EXCEPT 
      Thread.Alerted => Wr.PutText(stdout,"Alert!\n");
    | Rd.EndOfFile => Wr.PutText(stdout,"EOT\n");
    END;
    RETURN result;
  END Copy;
  
  VAR t := Thread.Fork(NEW(Thread.Closure, apply := Copy));
  
  BEGIN
    Thread.Alert(t);
    Wr.PutText(stdout,"Thread has been alerted.\n");
    Wr.PutText(stdout,Fmt.F("Read %s lines\n",
                            Fmt.Int(NARROW(Thread.Join(t),REF INTEGER)^)));
  END Alert.
  

  However, there's possibly a true bug left (SRC 1.6 SPARC). Using 
  Thread.AlertJoin(t) instead of of Thread.Join(t) has to raise 
  Thread.Alerted, since t is an alerted thread, but nothing happens.....


      
  Thomas



-- 
(*	Thomas Roemke, University of Paderborn, Germany 
	modula-3@uni-paderborn.de
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