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From: "Keith Allan Shillington" <keith@sd.aonix.com>
Subject: Re: File/Record locking in Ada
Date: 1997/02/28
Message-ID: <01bc259a$a035e850$fc00af88@godiva>#1/1
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References: <3313101D.1BBF@aston.ac.uk>
Organization: Aonix
Newsgroups: comp.lang.ada
Date: 1997-02-28T00:00:00+00:00
List-Id: <comp.lang.ada>


Hmmm.  That would be a protected type.

protected type Record_Lock is
  entry Lock;
  procedure Unlock;
private
  Locked : Boolean := False;
end Record_Lock;

protected body Record_Lock is
  entry Lock when not Locked is
  begin
    Locked := True;
  end Lock;
  procedure Unlock is
  begin
    Locked := False;
  end Unlock;
end Record_Lock;

(as in 9.4(26-29) RM95)

You can add complexity to your hearts content, but this is a single path
regardless of the number of tasks that interact with it.  Dijkstras rules on
semaphores apply.

Stephen Godwin <godwinsp@aston.ac.uk> wrote in article
<3313101D.1BBF@aston.ac.uk>...
> Does anyone know of a record locking method I can use in Ada?
> I've tried using the Forest(POSIX) libraries but can't get them to
> compile under Solaris.
> 
> Thanks,
> 
> Stephen Godwin
>