So setsockopt for timeouts on AF_UNIX (AF_LOCAL) sockets... undocumented/don't work... options/alternatives?
I'm running Fedora 13 if that matters.
I looked up man pages on unix(7), setsockopt, and send/recv.
Reading the man pages seems to more or less tell me that not all options are guaranteed to do ANYTHING... and apparently only a few that do/don't work are actually documented.
In particular... I wanted to see if timeouts were 开发者_开发技巧possible. At least on my system, SO_RCVTIMEO actually sets a timout for the recv family of calls... but SO_SNDTIMEO puts the socket seems to set it to non-blocking mode w/ no timeout.
So my question is... what can I do to workaround the fact that setsockopt isn't a reliable way to work with timeouts on AF_UNIX sockets?
Hmm, how about select(2)
or poll(2)
or epoll(4)
with a timeout?
what can I do to workaround the fact that setsockopt isn't a reliable way to work with timeouts on AF_UNIX sockets?
Well, don't use them.
I used epoll(4) in G-WAN (a Web App. Server) and had to face the same issue.
There are basically three ways to handle time-outs:
- timers (if you don't care about interrupting your code like a fool)
- polling (a dedicated thread with a loop to check fds, takes time)
- time-outs (like epoll_wait() with a time-out value, slows-down all)
Some use pipes to wake-up the fds you want to act on. My tests have shown that it is a tremendous waste of resources. Whatever you do, this will be either inefficient or tricky. Sometimes, both (thanks to idiotic kernel developers).
Good luck.
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