Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: Alexander Terekhov <terekhov@web.de>
Newsgroups: comp.programming.threads
Subject: Re: Interlocked operations, volatile
Date: Wed, 13 Jul 2011 20:03:01 +0200
Organization: A noiseless patient Spider
Lines: 42
Message-ID: <4E1DDDD5.AA6B4306@web.de>
References: <99a57186-cf9f-47ee-8955-07df1ce2b126@b21g2000yqc.googlegroups.com>
Reply-To: terekhov@web.de
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Injection-Info: mx04.eternal-september.org; posting-host="MCbSEzW5qwGLFMNXJh39IQ"; logging-data="15858"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX19ETkYvI0c4JV1YHqbshuDcoWGHzHN2tOc="
X-Mailer: Mozilla 4.77 [en] (Windows NT 5.0; U)
X-Accept-Language: en
Cancel-Lock: sha1:eJmT3OA/TnkY60mOBclA7Gh22RU=
Xref: x330-a1.tempe.blueboxinc.net comp.programming.threads:424


Andrew Che wrote:
> 
> Greetings!
> 
> Q1: Is it true that the only goal of using interlocked operations is
> to guarantee that read/write operations are completed in proper order?

Not true.

> Q2: Is it true that the goal of 'volatile' is the same?

Not true.

> Q3: Is it nessesary to use 'int* volatile ptr' or some interlocked
> operation in line [???] to be sure function2 is correct (see sample
> below)?

Not necessary.

> 
> == START SAMPLE ==
> 
> int value = 42;
> int* ptr = 0;
> 
> void function1 () { // called from many threads
>         cas(&ptr, &value, 0); // some compare-and-swap function
> }
> 
> void function2 () { // called from many threads
>         if(!ptr) { // [???]
>                 return;
>         some_func(ptr);
> }
> == END SAMPLE ==
> 
> Cheers,
> Andrew

regards,
alexander.