Asynchronicity

The asynchronous networking rework of Straw is progressing pretty nicely. I've already got the basics working: feeds are polled successfully and images are fetched. The only significant bit of code to be converted is the subscription tool / rssfinder.

It hasn't been totally easy. Converting an existing code base which depends on synchronous network operation to be asynchronous is a bit hairy in places. In fact, rssfinder is one beast which makes me consider leaving some synchronous networking in place, but we'll see about that.

Things aren't all peachy in the brand new asynchronous world, though; first of all fetching data over the network is, at the moment, noticeably slower than in 0.15. However, I suspect that tuning a few constants (timing and limits on open sockets) a bit might help here a lot. And Straw speaks HTTP 1.1, I could try using the same connections for multiple files, even though that would complicate the code a bit.

The second problem is that DNS lookups are still freezing the program. First thing to do, I guess, is to implement a name cache, so it'll be an one-time (per session) cost. But I suspect I'll have to do something about the lookup part itself. The options are, I guess, either using ADNS or forking a separate lookup process. I've been dependency-happy in the past, but I'll have to think what to do with this one; I have no idea how common ADNS is.

Oh, and a big THANK YOU to Fredrik Lundh for the series about building EffNews on his web site. I have no prior asynchronous networking programming experience, and his examples have been extremely helpful.