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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Protected Objects - eggshell model
Date: Tue, 23 Dec 2008 19:49:07 -0500
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Date: 2008-12-23T19:49:07-05:00
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hesobreira <herrsobreira@gmail.com> writes:

> This was not clear to me while reading Barnes' book about protected
> types.
>
> There are two conditions that must be satisfied in order to execute
> the entry call: no other task accessing the object at the same time
> and the condition barrier evaluated to TRUE (eggshell, or two level
> protection model). My question is: which one of these conditions is
> evaluated first, the access lock or the condition barrier?

The barrier is likely looking at variables that are protected by the
lock.  So the lock must be obtained first.

- Bob