IO work at YAPC.
22 Jun 2009The sysadmin heritage of Perl has really been shining through here at YAPC, a lot of our newcomers are really interested in process management and interprocess communication topics. Unfortunately, this seems to be an area where Parrot is particullarly weak. Luckily I managed to get a pretty good idea of the kinds of things that the workshop attendies are interested in, and even picked up a few good ideas about implementation. We had an "unconference" yesterday which is so awesome I would like to do it again some time. Earlier this morning I talked to a group of interested parties about the state of Parrot's GC, and may have found a volunteer to help implement the concurrent GC core I've been planning. I also did a little bit of talking about L1 to introduce the idea to people who haven't been following my blog (everybody on the planet besides myself). I'm just finishing up a session about IPC now, and have heard a lot about the things that people want, and heard lots of cool ideas about how to implement them.
I've been doing a lot of hacking on the io_cleanups branch, which I started two days ago. It was started with the goal of cleaning up the IO system a little bit and better integrating Sockets and Pipes. It's gone a little bit beyond that now, and I'm getting pretty close to having a cool result to share. I posted a patch to the IRC chatroom in hopes Infinoid would work his magic and tell me what I'm doing wrong. What I need to do is hunker down with the debugger and see where my stuff isn't working correctly, I just haven't been able to focus on it for long enough because of the festivities. I'm sure the problem has to do with my mishandling of the buffering code somewhere.
The gist of the work in the branch is this: The IO system should sanely handle all it's PMC types (FileHandle, Socket, Pipe, StringHandle), and handle them in a way such that they are subclassable from PIR. Currently we don't even have a separate Pipe type in trunk yet. Infinoid sent me a patch to add Pipes, and once I get past my current set of issues I will add it into the branch.
In order to make this all work, I changed the Handle type (which had been a mostly-useless parent type of all the IO PMCs) into a delegate type that implements all the non-subclassable attribute types that FileHandle used to use: the low-level file descriptor, the output buffer, etc. So now, FileHandle does not extend Handle, instead it has a Handle PMC as an attribute. Initially I ran into an interesting memory corruption problem where Handles were being destroyed before their parent. When FileHandle was destroyed it tried to flush it's contents to the Handle (which had already been garbage collected), and hilarity ensued. To get around that problem I moved all the buffering logic into Handle, which means any other PMC types that delegate to Handle (specifically Pipe seems like a good candidate for this) will get to have buffering for free if they want to use it. There are still some kinks to work out with this method, but once I get the implementation working it will be easier to get feedback from people.
In other YAPC news, Austin Hastings is working on a very cool C-like language compiler called Close. Basically, it's C-like syntax (curly brackets, if/else/for/while, etc). It looks to be on the same kind of level as NQP (low complexity, no runtime, good for writing PIR-level stuff that's not in PIR, etc). It really appeals to me because it's essentially a familiar syntax layer over PIR, which I find can be very tedious to write large things in as-is. He says he has a 0.1 release he's going to make public sometime soon, and I'm looking forward to that.
I talked to Patrick yesterday about my AIO plans, and he suggested I speak up about it on #perl6 to get some use-case information there. Obviously I don't want to tailor the work directly to Perl6's needs, but a flexible-enough system should satisfy them without too much wrapping and layering. Unfortunately the IO Synopses isn't entirely finalized, and there are a lot of things up in the air still. My AIO implementation, if well-enough received, could play a part in influencing that document.
Also, I MET LARRY WALL. HE WAS IN MY CAR! It was like nerd nirvana. I did, fortunately, manage to contain my school girl giggles and get us to the arrival dinner without making a complete ass of myself. Awesomeness.
So that was my Sunday at YAPC. It's now Monday morning and I'm looking forward to a full day of meeting people, watching cool presentations, and hacking hacking hacking. More blog posts to come, I'm sure.
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