Investigate Issues with Reachability Not Restored

[blakewatters]

Getting a number of reports about reachability issues not being restored properly.

[grgcombs]

I REALLY wish Apple would put together a real reachability framework with a thread-safe objective-c front-end. Until that day, SCReachabilityKit on GitHub works pretty great. There's also Andrew Donoho's more recent revisions to Apple's reachability class.

For what it's worth, I went with the former since it fit my project case better. I wrote a layer on top of it that looks primarily at known hosts, suitable for restkit type usage, and for any other unmonitored hosts, it just looks at general network reachability instead of doing another DNS lookup, etc.

The kicker is there's only one time where it uses the synchronous getFlags: method, on the initial watch. Everything else is asynchronous, to reduce blocking.

I can discuss more if needed, but if you find the SunlightLabs/StatesLege project, look in Classes/Helpers/SLFReachable.m

Don't bother trying to build the project though, not all submodules are open to the public yet.

G

Sent from my iPhone.

On Oct 14, 2011, at 1:47 PM, Blake Wattersreply@reply.github.com wrote:

Getting a number of reports about reachability issues not being restored properly.

Reply to this email directly or view it on GitHub:
#408

[grgcombs]

Two big things that I'll bring up in the conference call today:

• We wind up calling SCNetworkReachabilityGetFlags() a whole lot ... every time we check networkStatus or isNetworkReachable or isConnectionRequired. That's a synchronous call that can block the thread up to thirty-seconds every time we use it. What I discovered from using SCNetworkReachabilityKit is that we can get all the same utility out of reachability if we just catch those same flags passively from the userInfo dictionary (that kit handles all of that part). But there should only be one event that prompts you to call the synchronous library functions, and that's when you're just starting to monitor a host.
• The other big thing that I saw in that SCNetworkReachabilityKit was some unit tests for network access and reachability. He uses fake reachability flags to exercise the reachability code ... I've adopted some of that in my own thing and eventually I want to get it test that all my components react appropriately whenever network access is gone and then returns. We can do something similar for the RestKit spec environment I bet.

[grgcombs]

This restructuring looks good to me.