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Re: Ann: ANS/FORTH 2012 test suite update

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: Ann: ANS/FORTH 2012 test suite update
Date 2015-11-29 12:41 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2015Nov29.134145@mips.complang.tuwien.ac.at> (permalink)
References <n3acur$8s6$1@dont-email.me> <880ce15f-f5fb-45b0-94f3-a5db59293dec@googlegroups.com> <2c8fa539-4739-4d74-b1db-4f9eaf5eb5fb@googlegroups.com>

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"steve@srpalmer.me.uk" <steverpalmer27@gmail.com> writes:
>Moving forwards to modern times with 32+ bit processors and hardware memory=
> managers, I can quite understand the attraction of a memory mapped block f=
>ile.  All changes are automatically captured and there is no need for UPDAT=
>E or FLUSH or others.  I suspect that it will make the life on real Forth P=
>rogram using blocks to be much easier.  However, I don't think it is consis=
>tent with the language standard.

Instead of mmap()ing the blocks file with MAP_SHARED, one could also
use MAP_PRIVATE and then write out UPDATEd buffers explicitly with
write() on SAVE-BUFERS (replace the corresponding non-POSIX names on
non-POSIX OSs).  There would be no guarantee about consistency between
blocks files in two different processes, but the standard does not
give such a guarantee anyway.

>To test compliance with the standard, (at around line 555) I write a block =
>(UPDATEd and FLUSHed) to one value, then change it, UPDATE it, but then dis=
>card the changes using EMPTY-BUFFERS.  The expectation is that the block co=
>ntains the first value, not the second.  I guess that this is (at least one=
> of) the place where an error is being reported.  If I've misunderstood the=
> standard, then obviously the test should be changed, but I think that this=
> test is a fair reflection of, in particular, section 7.6.2.1330.

Yes.  However, Andrew Haley has pointed out how blocks are used on
multi-user systems.  Basically, you had to assume that, on every
potentially PAUSEing operation (all I/O), another task could do
anything with blocks.  In this setting, I expect that one would
UPDATE, then change and when you want to have everything on disk,
SAVE-BUFFERS.  EMPTY-BUFFERS does not make much sense in that kind of
setting (as an action that is used for a guaranteed outcome), but it
might have been used as an attempt at undoing the changes to the
buffer, without guarantee of success.

The standard does not cover such traditional cooperative
multi-tasking, and given that we are living in a world with
multi-cores, we probably should not limit ourselves to that model in
future standardization efforts.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/

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Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-27 20:06 +0000
  Re: Ann: ANS/FORTH 2012 test suite update Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-27 22:19 -0800
  Re: Ann: ANS/FORTH 2012 test suite update peter.m.falth@gmail.com - 2015-11-28 10:07 -0800
    Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-29 10:13 +0000
    Re: Ann: ANS/FORTH 2012 test suite update "steve@srpalmer.me.uk" <steverpalmer27@gmail.com> - 2015-11-29 03:47 -0800
      Re: Ann: ANS/FORTH 2012 test suite update Albert van der Horst <albert@spenarnc.xs4all.nl> - 2015-11-29 12:41 +0000
      Re: Ann: ANS/FORTH 2012 test suite update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-29 12:41 +0000
      Re: Ann: ANS/FORTH 2012 test suite update peter.m.falth@gmail.com - 2015-11-29 08:41 -0800
        Re: Ann: ANS/FORTH 2012 test suite update peter.m.falth@gmail.com - 2015-11-29 10:47 -0800
          Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-29 20:29 +0000
            Re: Ann: ANS/FORTH 2012 test suite update peter.m.falth@gmail.com - 2015-11-29 14:44 -0800
              Re: Ann: ANS/FORTH 2012 test suite update Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-30 01:24 +0100
                Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 09:35 +0000
                Re: Ann: ANS/FORTH 2012 test suite update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-30 18:04 +0000
                Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 21:28 +0000
                Re: Ann: ANS/FORTH 2012 test suite update Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-30 22:59 +0100
                Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-12-01 12:29 +0000
                Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-12-02 10:08 +0000
                Re: Ann: ANS/FORTH 2012 test suite update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-12-05 15:57 +0000
              Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 09:49 +0000
                Re: Ann: ANS/FORTH 2012 test suite update anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-30 18:16 +0000
                Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 21:28 +0000
              Re: Ann: ANS/FORTH 2012 test suite update Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 10:25 +0000
          Re: Ann: ANS/FORTH 2012 test suite update "Elizabeth D. Rather" <erather@forth.com> - 2015-11-29 13:14 -1000
          Re: Ann: ANS/FORTH 2012 test suite update steverpalmer27@gmail.com - 2015-11-30 03:51 -0800
            Re: Ann: ANS/FORTH 2012 test suite update peter.m.falth@gmail.com - 2015-11-30 09:00 -0800
              Re: Ann: ANS/FORTH 2012 test suite update "Elizabeth D. Rather" <erather@forth.com> - 2015-11-30 07:54 -1000
                Re: Ann: ANS/FORTH 2012 test suite update Albert van der Horst <albert@spenarnc.xs4all.nl> - 2015-11-30 18:25 +0000
                Re: Ann: ANS/FORTH 2012 test suite update "Elizabeth D. Rather" <erather@forth.com> - 2015-11-30 11:06 -1000
      Re: Ann: ANS/FORTH 2012 test suite update "Elizabeth D. Rather" <erather@forth.com> - 2015-11-29 13:08 -1000

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