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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: S-expression I/O in Ada
Date: Wed, 11 Aug 2010 18:32:39 +0100
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Date: 2010-08-11T18:32:39+01:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On Tue, 10 Aug 2010 22:22:02 +0100, Simon Wright wrote:
>
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>> 
>>> Yes, if TCP sockets is what you use. There is a hell of other
>>> protocols even on the Ethernet, some of which are not stream-oriented.
>> 
>> We leverage stream i/o via UDP (which on GNAT is seriously broken,
>> because it tries to do an OS sendto() for each elementary component!
>
> Wow! Even in the latest GNAT Pro/GPL?
>
> I am asking because AdaCore fixed this very issue for String'Write, which
> did Character'Write per element. Was it String-only fix?

There was an efficiency problem, where GNAT did as you say. I raised a
ticket but don't recall what happened about it (we are stuck with an
archaic GNAT, don't ask).

But I think you will still find that a String is still written as a
C_Sendto of an Integer (Item'First), another Integer (Item'Last) and
then (if this change has been made!) the String itself.

Checked in 6.2.2.

The best cure IMHO is to refuse to return a Stream for a Datagram_Socket.