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From: "David C. Hoos, Sr." <david.c.hoos.sr@ada95.com>
Subject: Re: Interrupt problem in GNAT
Date: 1999/05/19
Message-ID: <7huup6$qoa@hobbes.crc.com>#1/1
X-Deja-AN: 479729356
References: <3742DC0D.B8F07A52@epfl.ch>
Organization: Coleman Research Corporation
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3612.1700
Newsgroups: comp.lang.ada
Date: 1999-05-19T00:00:00+00:00
List-Id: <comp.lang.ada>


Joerg Kienzle wrote in message <3742DC0D.B8F07A52@epfl.ch>...
>
<large snip>
You did not say on which platform you are trying to do this, so
I'm assuming sparc and not x86 Solaris.

There is a problem with what you're trying to do.

   First, if you use the dynamic attach instead of the static (pragma),
   you will find that Interrupt 14 (Sigalrm) is reserved, and Program_Error
   is raised.  Apparently with the static attach, it just silently fails.

   I have always used the dynamic attach myself, but I just tried your
   program with SIGTERM and SIGWINCH, by outputting a line of
   text in the Tick procedure.  Both of those signals work with either
   static or dynamic attach on a SPARCstation-10 with SunOS 5.5.1,
   sending the signals with kill <PID> or kill -WINCH <PID>.

Have you ever considered just using the facilities of Ada to do
what you want?

Using the package for which I have appended source code
to this message (courtesy of Burns and Wellings),

you can have a signal handler that pends at the entry call
Wait.  Then, when the signal arrives it can do its thing, and
loop back to pend on the Wait call again.

Meanwhile, you have a task which does nothing but loop
delaying 6.0 seconds, then calling the Send entry of the
signal on which your handler is pending.

Just a thought -- but such an approach is much more
likely to be portable.

David C. Hoos, Sr.

-- begin source code --
package Persistent_Signals is
   protected type Signal_Type is
      procedure Send;
      entry Wait;
   private
      Signal_Arrived : Boolean := False;
   end Signal_Type;
end Persistent_Signals;

package body Persistent_Signals is
   protected body Signal_Type is
      procedure Send is
      begin
         Signal_Arrived := True;
      end Send;
      entry Wait when Signal_Arrived is
      begin
         Signal_Arrived := False;
      end Wait;
   end Signal_Type;
end Persistent_Signals;
-- end source code --