Tasking

Tasking

[Tod Trowbridge]

    I just started programming in ada and have a general 
question about tasking.

    I have a task in a package.  If a procedure that withs
that package calls the task, does the task have to be waiting
at the accept statement, or will the procedure wait for the
task to get there.

           Any help in this matter would be greatly appreciated

                                Thanks

Re: Tasking

[Theodore E. Dennison]

Tod Trowbridge wrote:
> 
>     I have a task in a package.  If a procedure that withs
> that package calls the task, does the task have to be waiting
> at the accept statement, or will the procedure wait for the
> task to get there.

The procedure will wait for the task to "accept". 

If you want the other behavior you described, use a select
statement of the following form:
   select
      entry_call_statement
      [sequence_of_statements]
   else
      sequence_of_statements
   end select;

This is called a "Conditional Entry Call".

-- 
T.E.D.          
                |  Work - mailto:dennison@escmail.orl.mmc.com  |
                |  Home - mailto:dennison@iag.net              |
                |  URL  - http://www.iag.net/~dennison         |

Re: Tasking

[Mark Fisher]

It can work either way...

The procedure making the call to the entry point
will be suspend execution until the task reaches the
accept statement.

If the task reaches the accept statement first,
it will block (suspend) until the procedure makes
the entry call. 

simple when you know ...

Mark

tasking

[grave]

Hi,

I'm wanting to kill a task to let an exception propagate and kill the
process. How can I do this if the task is already excuting some part of
code like this :

select
   entry start;
   
or
   terminate;
end select;

Here I'm wanting to kill the task when it works in Do_Some_Stuff_Here;

Is this possible ?

Tasking

[Chang Yang Lim]

I tried to use Tasking in my project recently. It worked fine sometimes.
However, it does give me a trouble, i don' t know why sometimes i got
"Segmentation fault". at first i thought maybe i passed the pointer
wrong, however, later i found it's not my problem. can anyone help me?

Re: Tasking

[David C. Hoos, Sr.]

Chang Yang Lim wrote in message
<36287E02.C9F4908D@teaching.cs.adelaide.edu.au>...
>I tried to use Tasking in my project recently. It worked fine sometimes.
>However, it does give me a trouble, i don' t know why sometimes i got
>"Segmentation fault". at first i thought maybe i passed the pointer
>wrong, however, later i found it's not my problem. can anyone help me?
>
It's virtually impossible to provide help when you do not specify any of the
following:

OS
OS version
compiler
compiler version

Furthermore, you need to be more specific about the conditions under which
the problem occurs, and possibly supply the failing source code.

Tasking

[Chang Yang Lim]

Hi everyone, I have problems with tasking again. ok, let me put in this
way:
I am using  protected xxxx is  in the main program. however, there are
few things that i will load the procedures from another package. All
procedures loaded from other packages are running in tasking.
and procedures will need to access the variables in protected part. how
am i suppose to do that?
eg.
protected x is
    procedure save(...);
    procedure load(...);
private
    x : ...
end protected
task type a is
end a;
type a_access is access a;
task body a is
begin
    yyyy(...) -- from other packages, and in this procedure, it will
access the values in the protected body part.
end a;

I appreciate someone can give me some guidelines. Thank you.

CY.

Tasking

[krischik]

Hello,

we have a question about Tasking at wikibooks:

http://en.wikibooks.org/wiki/Talk:Ada_Programming/Tasking

Anybody can help us out here?

Martin

Re: Tasking

[Maciej Sobczak]

krischik wrote:

> we have a question about Tasking at wikibooks:
> 
> http://en.wikibooks.org/wiki/Talk:Ada_Programming/Tasking
> 
> Anybody can help us out here?

The task can become terminated before it even gets activated, it can 
also become terminated by abortion...

The book "Concurrency in Ada" by Burns&Wellings has a nice set of 
diagrams like the one started in the wikibook - the diagrams get more 
complete (and complicated) with each chapter, as the details are added.


-- 
Maciej Sobczak : http://www.msobczak.com/
Programming    : http://www.msobczak.com/prog/

Re: Tasking

[christoph.grein]

           Not_Yet_Activated
                 |
                 | Activate
                 v
      .----- Activating ----.
      |          |          |
      |          | Begin    |
      |          V          | Unhandled
Abort +------ Active -------+ Exception
      |          |          |
      |          | End      |
      v          v          |
  Abnormal   Completed <----'
      |          |
      |          | Terminate
Abort |          v
 or   `---> Terminated
End of
Redezvous

Re: Tasking

[Dmitry A. Kazakov]

On 15 Dec 2005 23:33:30 -0800, krischik wrote:

> we have a question about Tasking at wikibooks:
> 
> http://en.wikibooks.org/wiki/Talk:Ada_Programming/Tasking
> 
> Anybody can help us out here?

Abort?

I think that under certain circumstances it could bring a task from
blocked/ready state to the terminated state.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de