From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <52B231AD.2010604@alaxarxa.net> Date: Thu, 19 Dec 2013 00:37:17 +0100 From: Leopold Palomo-Avellaneda MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: [Xenomai] Xddp protocol: question of one example List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org Hi, I'm developing an application that need (as always) interchange data between a realtime part and non-realtime. Looking on the documentation and surfing on the web I have found interesting for my app the examples of xddp protocol. Some time ago, there was an interesting mail about it [1]. There, the original author ask one thing that I would like to be sure that I understood. On the examples, the realtime thread uses the function recvfrom() to receive data from the non-rt thread. In the mail, the original author asked about make recvfrom call non-blocking in xddp context, and *Philippe Gerum* answered that MSG_DONTWAIT should be set in flags. So, my question is that using that flag, some code like this: /* Read back packets echoed by the regular thread */ ret = recvfrom(s, buf, sizeof(buf), 0, NULL, 0); if(ret <= 0) fail("recvfrom"); recvfrom will not be blocked, but it will return 0? May I understood that if there's data on the sockect recvfrom will return something and if no, it would not be blocked and return something? Thanks in advance, Leopold [1] http://www.xenomai.org/pipermail/xenomai/2010-February/019364.html -- -- Linux User 152692 PGP: 0xF944807E Catalonia ------------------------------------- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?