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NNTP-Posting-Date: Tue, 10 Jun 2008 19:35:38 -0500
From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Post hoc making a type thread safe
References: <6b7vr9F3b6cjlU1@mid.individual.net>
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Date: Tue, 10 Jun 2008 19:35:39 -0500
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Date: 2008-06-10T19:35:39-05:00
List-Id: <comp.lang.ada>

This isn't exactly what you appear to be asking for, but perhaps
it would do what you need.

In Claw.Sockets, it's desirable to avoid one thread trying to do
something with a socket while another thread is in the middle of
some activity with that socket.  Our solution was a Controlled
type whose declaration at the beginning of a procedure would
raise an exception if the socket is already busy having something
done to it by another task, or would set a Busy flag if the socket
is not busy.  On leaving the routine the Finalize will clear the
Busy state.

Once the mechanism is set up, this just requires a single line declaration
    Check_Busy : Check_Busy_Type(Socket'unchecked_access);
to be included at the beginning of each routine to be interlocked.