Re: The possible reasons for SOCK_DGRAM packet loss in PF_LOCAL domain
Re: The possible reasons for SOCK_DGRAM packet loss in PF_LOCAL domain
- Subject: Re: The possible reasons for SOCK_DGRAM packet loss in PF_LOCAL domain
- From: Paul M <email@hidden>
- Date: Fri, 7 Jan 2011 15:29:55 +1300
Hi Nick,
Not directly answering your qusetion, but ...
Personally, I havn't found this to be a problem. If you need
reliability, then build it in to your app - when a datagram is sent,
the receiver sends back an acknowlegement. If nesessary, include
checksums to ensure the message is recieved intact - if not then
resend.
I've been using such techniques fairly extensively of late, and packet
drop has never been a problem.
I think people make a much bigger deal of the fact that UDP
communication is unreliable than is warranted. You just need to be
aware of the issues and code appropriately.
paulm
On 7/01/2011, at 2:04 PM, eveningnick eveningnick wrote:
Hello
I am wondering what could possibly cause the loss of the datagram in
User Domain Sockets communication.
i am aware that SOCK_DGRAM is a connectionless and therefore
unreliable way of communication (in PF_INET).
But what could be the reason for packets to be lost in LOCAL domain?
There are no routers, and no "dead" routes. There is no
electromagnetic interference.
Does the system drop them when its out of resources (when there's no
more memory for new mbufs)? I can't see any other possible scenario.
I haven't found any information about its unreliability in this
domain, except one person's statement about Mac OS X's behaviour. Thus
i am unsure if i could use them (or if not, why?).
I only noticed that sendto blocks unless recvfrom receives data.
Recvfrom blocks, until sendto sends data. They never returned errors.
Thanks for the answer!
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