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From: Florian Weimer <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
Subject: Re: Robert Dewar's great article about the Strengths of Ada over
 other langauges in multiprocessing!
Date: Wed, 26 Mar 2008 22:27:29 +0100
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* Ole-Hjalmar Kristensen:

> If the compiler is smart enough to optimize this case, an entryless
> protected object would be a good building block.
>
> The AARM states that "Entryless protected objects are intended to be
> treated roughly like atomic objects -- each operation is indivisible
> with respect to other operations (unless both are reads), but such
> operations cannot be used to synchronize access to other nonvolatile
> shared variables"

You need some signaling for a shared hash table, otherwise reading a
freshly-added object from a different thread might not give you the data
you want (strictly speaking, even just comparing the might cause
issues).