From: Lionel Bouton <lionel-subscription@...>
Date: 2008-03-22T00:04:52+09:00
Subject: Re: Test for Internet Connection

Cory Cory wrote:
>>   sudo gem install dbus
> 
> Well after all of that, I can't compile the dbus gem unless I download 
> and compile the newest version of the real dbus (because the deb is 
> still out of date).  Interfering with my deb's is not something I like 
> doing because of updates, so I guess I'll just have to wait.
> 
> Maybe Hardy Heron will solve my problems.
> 
> If Ruby just had system threading this would not even be an issue.

Your problem isn't clear enough for a good advice : do you need an 
answer to the "Is net available?" in finite time or do you want to 
continue processing while you wait for the answer?

If you want to continue processing, your only need is a non-blocking 
communication channel with another process/thread. The usual solution is 
to use an event loop, in this case something like popen with the ping 
program or whatever you need would give you the asynchronous behaviour 
you need.

I've a strong opinion on threads (built on several projects where 
avoiding deadlocks between them took most of my time instead of adding 
functionnalities): if you can avoid them (don't need the power of 
several CPU cores and even then multi-process is an option), go for the 
event-loop. In Ruby's case, where multi-threading doesn't use multiple 
cores, I only use threads in the simplest conditions (fetching several 
URIs in parallel with no interlocking for example).

If you only need an answer in finite time, see man ping on your OS.

Lionel