[m-rev.] for review: move more concurrency modules to stdlib

[Julien Fischer]

On Tue, 30 Jan 2007, Peter Wang wrote:

> Branches: main
>

Add a brief log message, e.g.

 	Move more of the concurrency related modules from extras
 	into the standard library.

> library/Mercury.options:
> library/library.m:
> library/thread.channel.m:
> library/thread.mvar.m:
> library/thread.semaphore.m:
> 	Move the concurrency-related modules `channel', `mvar' and
> 	`semaphore' from extras/concurrency into the standard library.
>
> 	Make thread.mvar use the standard library module mutvar instead of
> 	providing its own implementation of the same thing.

The NEWS file should also be updated.

> library/mutvar.m:
> 	Add predicate `new_mutvar0' which is like `new_mutvar' but does not
> 	require an initial value for the mutvar.  This is needed for
> 	thread.mvar.
>
> 	Define `new_mutvar' in terms of `new_mutvar0' and `set_mutvar'.
>
> extras/concurrency/channel.m:
> extras/concurrency/mvar.m:
> extras/concurrency/semaphore.m:
> 	Replace predicates to call their counterparts now in the standard
> 	library.
>
> 	Mark them as obsolete and add pointers to the new versions.
>
> library/thread.m:
> 	Fix a bug in which a field in ML_ThreadWrapperArgs had the wrong
> 	pointer type.
>
> 	Allocate ML_ThreadWrapperArgs with MR_GC_* macros instead of non-GC
> 	versions, since it contains pointers which should be traced.
>
>
> mmake has trouble building things in extras/concurrency after this
> change.  When generating dependencies it thinks semaphore.m is the
> source file for thread.semaphore, etc.  Would it be a problem just to
> remove the forwarding modules?

I wouldn't think so, other than the example code in extras/concurrency
would need to be updated.

...

> Index: library/mutvar.m
> ===================================================================
> RCS file: /home/mercury/mercury1/repository/mercury/library/mutvar.m,v
> retrieving revision 1.2
> diff -u -r1.2 mutvar.m
> --- library/mutvar.m	19 Apr 2006 05:17:53 -0000	1.2
> +++ library/mutvar.m	30 Jan 2007 03:41:07 -0000
> @@ -33,6 +33,11 @@
> :-        mode new_mutvar(in, out) is det.
> :-        mode new_mutvar(di, uo) is det.
>
> +    % Create a new mutvar with undefined initial value.
> +    %
> +:- impure pred new_mutvar0(mutvar(T)).
> +:-        mode new_mutvar0(uo) is det.
> +
>     % Get the value currently referred to by a reference.
>     %
> :- impure pred get_mutvar(mutvar(T), T) is det.
> @@ -58,10 +63,18 @@
> :- implementation.
>
> :- pragma inline(new_mutvar/2).
> +:- pragma inline(new_mutvar0/1).
> :- pragma inline(get_mutvar/2).
> :- pragma inline(set_mutvar/2).
>
> %-----------------------------------------------------------------------------%
> +
> +new_mutvar(X, Ref) :-
> +    impure new_mutvar0(Ref0),
> +    impure set_mutvar(Ref0, X),
> +    Ref = unsafe_promise_unique(Ref0).
> +
> +%-----------------------------------------------------------------------------%
> %
> % C implementation
> %
> @@ -72,22 +85,12 @@
>     --->    mutvar(private_builtin.ref(T)).
>
> :- pragma foreign_proc("C",
> -    new_mutvar(X::in, Ref::out),
> -    [will_not_call_mercury, thread_safe],
> -"
> -    MR_offset_incr_hp_msg(Ref, MR_SIZE_SLOT_SIZE, MR_SIZE_SLOT_SIZE + 1,
> -        MR_PROC_LABEL, ""mutvar.mutvar/1"");
> -    MR_define_size_slot(0, Ref, 1);
> -    * (MR_Word *) Ref = X;
> -").
> -:- pragma foreign_proc("C",
> -    new_mutvar(X::di, Ref::uo),
> +    new_mutvar0(Ref::uo),
>     [will_not_call_mercury, thread_safe],
> "
>     MR_offset_incr_hp_msg(Ref, MR_SIZE_SLOT_SIZE, MR_SIZE_SLOT_SIZE + 1,
>         MR_PROC_LABEL, ""mutvar.mutvar/1"");
>     MR_define_size_slot(0, Ref, 1);
> -    * (MR_Word *) Ref = X;
> ").
>
> :- pragma foreign_proc("C",
> @@ -110,18 +113,10 @@
> %
>
> :- pragma foreign_proc("C#",
> -    new_mutvar(X::in, Ref::out),
> +    new_mutvar0(Ref::uo),
>     [will_not_call_mercury, thread_safe],
> "
>     Ref = new object[1];
> -    Ref[0] = X;
> -").
> -:- pragma foreign_proc("C#",
> -    new_mutvar(X::di, Ref::uo),
> -    [will_not_call_mercury, thread_safe],
> -"
> -    Ref = new object[1];
> -    Ref[0] = X;
> ").
>
> :- pragma foreign_proc("C#",
> @@ -147,26 +142,16 @@
> "
>     public static class Mutvar {
>         public Object object;
> -
> -        public Mutvar(Object init) {
> -            object = init;
> -        }
>     }
> ").
>
> :- pragma foreign_type("Java", mutvar(T), "mercury.mutvar.Mutvar").
>
> :- pragma foreign_proc("Java",
> -    new_mutvar(X::in, Ref::out),
> -    [will_not_call_mercury, thread_safe],
> -"
> -    Ref = new mercury.mutvar.Mutvar(X);
> -").
> -:- pragma foreign_proc("Java",
> -    new_mutvar(X::di, Ref::uo),
> +    new_mutvar0(Ref::uo),
>     [will_not_call_mercury, thread_safe],
> "
> -    Ref = new mercury.mutvar.Mutvar(X);
> +    Ref = new mercury.mutvar.Mutvar();
> ").
>
> :- pragma foreign_proc("Java",

...

> Index: library/thread.semaphore.m
> ===================================================================
> RCS file: library/thread.semaphore.m
> diff -N library/thread.semaphore.m
> --- /dev/null	1 Jan 1970 00:00:00 -0000
> +++ library/thread.semaphore.m	30 Jan 2007 03:41:07 -0000
> @@ -0,0 +1,341 @@
> +%-----------------------------------------------------------------------------%
> +% vim: ft=mercury ts=4 sw=4 et
> +%-----------------------------------------------------------------------------%
> +% Copyright (C) 2000-2001,2003-2004, 2006-2007 The University of Melbourne.
> +% This file may only be copied under the terms of the GNU Library General
> +% Public License - see the file COPYING.LIB in the Mercury distribution.
> +%-----------------------------------------------------------------------------%
> +%
> +% File: thread.semaphore.m.
> +% Main author: conway
> +% Stability: medium.
> +%
> +% This module implements a simple semaphore data type for allowing
> +% coroutines to synchronise with one another.
> +%
> +% The operations in this module are no-ops in the hlc grades which don't
> +% contain a .par component.
> +%
> +%-----------------------------------------------------------------------------%
> +
> +:- module thread.semaphore.
> +:- interface.
> +
> +:- import_module bool.
> +:- import_module io.
> +
> +%-----------------------------------------------------------------------------%
> +
> +:- type semaphore.
> +
> +    % new(Sem, !IO) creates a new semaphore `Sem' with it's counter
> +    % initialized to 0.
> +    %
> +:- pred semaphore.new(semaphore::out, io::di, io::uo) is det.
> +
> +    % wait(Sem, !IO) blocks until the counter associated with `Sem'
> +    % becomes greater than 0, whereupon it wakes, decrements the
> +    % counter and returns.
> +    %
> +:- pred semaphore.wait(semaphore::in, io::di, io::uo) is det.
> +
> +    % try_wait(Sem, Succ, !IO) is the same as wait/3, except that
> +    % instead of blocking, it binds `Succ' to a boolean indicating
> +    % whether the call succeeded in obtaining the semaphore or not.
> +    %
> +:- pred semaphore.try_wait(semaphore::in, bool::out, io::di, io::uo) is det.
> +
> +    % signal(Sem, !IO) increments the counter associated with `Sem'
> +    % and if the resulting counter has a value greater than 0, it wakes
> +    % one or more coroutines that are waiting on this semaphore (if
> +    % any).
> +    %
> +:- pred semaphore.signal(semaphore::in, io::di, io::uo) is det.
> +
> +%-----------------------------------------------------------------------------%
> +%-----------------------------------------------------------------------------%
> +
> +:- implementation.
> +
> +%-----------------------------------------------------------------------------%
> +
> +:- pragma foreign_decl("C", "
> +    #include <stdio.h>
> +    #include ""mercury_context.h""
> +    #include ""mercury_thread.h""
> +
> +    typedef struct ME_SEMAPHORE_STRUCT {
> +        int     count;
> +#ifndef MR_HIGHLEVEL_CODE
> +        MR_Context  *suspended;
> +#else
> +  #ifdef MR_THREAD_SAFE
> +        MercuryCond cond;
> +  #endif
> +#endif
> +#ifdef MR_THREAD_SAFE
> +        MercuryLock lock;
> +#endif
> +    } ME_Semaphore;

s/ME_/ML_/ throughout otherwise the namespace cleanliness check on the
library directory will fail.

Otherwise that looks okay.  Please make sure that the library still
compiles in a non .par grade, e.g hlc.gc, before comitting.

Julien.
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