partiallydisassembled.net

Snow Leopard WiFi

2009-09-06 13:23:19

That thing about deleting the VPN profile turned out to be a red herring, the problem returned after a few hours. Finally solved it today, by setting the DNS server to my ISP, rather than my router/modem. Doing the same on my iPhone also solved its WiFi issues, which have been annoying me since the 2.1 OS update. I guess whatever DNS stack change was made on iPhone was backported to Snow Leopard, and it happens to interact poorly with my modem (Billion BiPAC 7300RA, for the record). I still don't quite understand where in the OS X software stack the problem is; since DNS lookups against the router work fine using nslookup; I'm guessing it's something in the Cocoa layer.

More Snow Leopard thoughts

2009-09-02 22:53:48

I seem to have fixed my earlier WiFi issues by deleting the (unused and disabled) university VPN profile. Many people have written that there are virtually no new front-facing features in SL. The only ones that affect me are: - Under 10 seconds from cold boot to ready-to-use. That's really, really insane. - You can show the date in the menu bar next to the clock now. But the new APIs are really interesting. Read the Ars Technica review for a really long exposition. Read the Apple developer notes for a faster, more detailed explanation. Some highlights: - Block objects in C (i.e., closures). - Grand Central Dispatch: POSIX-level threading API that cooperates across processes to balance work units across an optimal number of threads. The API is dead simple, using the aforementioned C block objects. - OpenCL: numeric for GPU, without fucking about with textures, render targets and full-screen quads. - Explicit cache control: mark pages as volatile, and the OS will flush them without paging them out if it needs to. - Opt-in application termination: shutdown doesn't wait for processes to exit if they've marked themselves as "safe for immediate termination". - File ID-based URLs replacing POSIX paths; unifies URLs and paths, and means applications can find files after they've been moved (if they're on the same volume). Presumably also does away with having to worry about relative vs absolute paths (if you don't care about changing volumes). - QuickTime X: simpler APIs for things like playing back movies/audio that don't require you to read documentation that dates from the 80's. Rampant speculation: For the last few years we've been developing in an environment in which the three platforms (Windows, OS X and Linux) are approximately equivalent in features and APIs. OS X and Linux to the point where you can often cross-compile the same source code with minor changes [I recently recompiled a Linux networking library for iPhone changing only a single #include directive]. The Win32 equivalent functions for POSIX are well-known and easy to find. Writing cross-platform software is a matter of factoring out the common code, and either rewriting the user interface for each platform, or using something like Qt to smooth over virtually all of the differences. Using a cross-platform language like Java or Python makes it even more of a no-brainer. But it looks to me like the platforms are diverging again. OS X is gaining features that are genuinely useful (not just eye-candy or domain-specific) that have no equivalents in Windows or Linux. Microsoft have had big plans for Windows, too. None of these plans (besides Vista's transactional filesystem) seem to have made it into Vista or 7, but it's reasonable to expect that some of them will eventually make it into a product. At the very least, it's clear that Microsoft's focus is on supporting .NET/CLR rather than the C API now and in the future. Someone writing a Photoshop-like application for OS X would definitely want to use a whole lot of OS X specific features: CoreImage, CoreAnimation, OpenCL, the cache APIs, Grand Central, and so on. These features are not just "nice-to-have" additions, they change the way you'd develop the application. Similarly, the same application written for Windows nowadays would probably want to start with .NET, at the very least to get the most up-to-date GUI look. The amount of code that could be shared between the two implementations gets smaller the more you improve it for any particular platform. Cocoa/Objective-C code and .NET/C# code don't look very much alike at all, especially when you really start taking advantage of them. That leaves choosing an in-between language (C++) and doing without a bunch of features, or a cross-platform language (Java/Python) and also doing without a bunch of features (and looking like poo, to boot). I'd guess this is exactly where both Apple and Microsoft want us going, because it again allows each platform to have its own speciality apps and points of difference, where for a while they were more or less interchangeable. While the split between OS X and Windows increases, the difference between the desktop and mobile editions is vanishing. OS X and iPhone APIs were always similar, and now features from iPhone are being back-ported to OS X (CoreLocation and QuickTime X). Rumour has it that the next Zune API will be XNA. That leaves two fairly serious platforms to choose between: Windows/WindowsMobile/Zune/Xbox and OS X/iPhone. Game developers also target PSP (conceptually similar to iPhone), PS3 and DS (like nothing else, from what I understand). I don't think the cross-platform languages (Python, Java, etc) and libraries (Qt, etc) will be relevant for much longer. When the Windows/Mac split increases more, cross platform development will be the domain of Javascript+HTML+Canvas, which is starting to look like a real platform since the announcement of Google Chrome OS, and has the benefit of actually being cross platform by design.

Snow Leopard WiFi

2009-09-02 08:27:47

Something's very, very wrong. Command-line programs like ping and curl work fine. Safari, Camino, Firefox routinely think they have no internet connection and give up trying. Some things that help: - Flushing the DNS cache (fixes problem for one web page fetch) - Restarting WiFi, or creating a new "location" in system preferences (an oft-quoted solution to this problem on the forums) -- fixes problem for nearly a minute - Restarting computer (which, incidentally, is an insanely fast 10 seconds) -- fixes problem for about a minute. This is on a late 2008 model MacBook connecting to a NetGear router. Things I've yet to try: - Put the kernel in 64-bit mode - Try another router (I have an old Apple one) - Downgrade to Leopard (clean install I imagine -- shudder).

Javascript types

2009-05-27 23:21:08

Javascript has won the language wars, and look what we've got. A single Number type (hooray), which is internally represented by a 64-bit IEEE float (erm, ok) unless you're doing bitwise operations, in which case it's: - violently coerced to a 32-bit signed integer in JS <= 1.1 (NaN if out of range) - silently coerced to a 32-bit signed integer in JS > 1.1 (truncated fractional and high bits) What have we done to deserve this? (Disclaimer: I haven't been bitten by this design decision of doom, because I don't do any Javascript programming. But I find myself strangely compelled not to even bother, given the risks apparent).

About Reader

2009-05-05 09:18:27

I said that comments on Reader really suck in my last post, and I want to explain why. Google Reader has changed my life (this is no big statement; lots of things change my life; including whichever bastard on one of the many overcrowded trains I catch coughed on me and gave me this cold; keeping me home from work and thus with too much time to blog inanities, like this one). Reader started out as a feed aggregator. Technologically, this means checking the timestamps of a predetermined list of remote files, and downloading any that have changed. The point of which was to keep up-to-date with news (real news, from newspapers; tech news, from procrastination web sites; or friends' news, from blogs). When Reader was released, there were hundreds of desktop applications that did exactly the same thing -- Reader's advantage was that it followed you between desktops, being online. But it's so much more now. Reader is how I keep in contact with friends. People of my generation don't actually want to talk to their friends, or even SMS or email them. That kind of contact is far too personal and touchy. All we need is some way of indicating that we thought about each other, if only for a moment. This can be achieved on Facebook with a nudge, on MySpace with a chain letter, on Twitter with a 140-character brain broadcast, and on Reader by sharing something. To each their own (or, in the case of some people I know, all of them). When you share an article on Reader, you're telling them, "Hey, I saw this and think you should read it." Which is how most conversations go anyway. Except for Austin, who mostly shares pictures of animals, but mostly talks about compilers. Originally you could only share articles from feeds; typically ones you'd subscribed to. But some time recently Google added the ability to share any URL with a single click. This has changed my friend's sharing habits from keeping each other up-to-date on the few blogs that we don't subscribe to in common, to keeping each other up-to-date with what we're doing all day. For example, based on Sofie's shares from yesterday, I can surmise that she was passing the time by reading about penises and Star Trek cakes. This tells me much more about Sofie than I could ever have learned by actually talking to her. And then there's commenting. In response to a friend's share, you can write something back. Usually "hahaha", with the number of "ha"'s being proportional to the amount of enjoyment you received. This comment is then viewable by any other friend looking at that shared item. Occasionally one of us tries to start some discourse via the comments. Say, if you didn't agree with the shared article, you might comment, "lolz no way ps3 is teh better than poniez". But this is where it all breaks down, because anyone who's already read that item will not see your comment, unless they specifically go looking for it. There isn't even a flag or a number to indicate that articles you've read have since been commented on. At the moment Reader is like a party where everyone is telling jokes, and everyone is hearing the jokes, but no-one can hear all the laughter, which is isolated. If comments were integrated into the main view -- say, given first-class status as another article, then we'd be able to continue the discussion past a single retort, and have a real argument. It makes me think of Slashdot, except that the posting of articles and comments would be restricted to just the people on your friends list. It's what I want! (Side note: apparently whatever spell-check dictionary I have loaded on my Mac at the moment understands "MySpace" but not "Facebook" or "Google". Figure that one out!)