The alsa “force-reload” command will kill all running programs using the sound driver so the driver itself is able to be restarted.

Huh. Didn’t know about that one. But seems reasonable, and sure enough,

$ /sbin/alsa force-reload

did the trick.

That wiki page goes on to detail adding a script to /etc/pm/sleep.d to carry this out after every resume. That seems excessive; I know that sometimes drivers don’t work or hardware doesn’t reset after the computer has been suspended or hibernated, but in my case the behaviour is only intermittent, and seems related to having docked (or not), having used an external USB headphone (or not), and having played something with Flash (which seems to circumvent PulseAudio. Bad). Anyway, one certainly doesn’t want to kill all one’s audio-using programs just because you suspended! But as a workaround for whatever it is that’s wrong today, nice.

AfC

The café’s upstream ISP is “Optus”, one of the major Australian carriers. To my astonishment I found that Optus’s DNS servers are interfering with Google searches, stealing their DNS lookups and serving results pages on their own (shitty quality) branded search instead! Try https:? No connection; and Google+ wouldn’t load either.

Obviously as soon as realized what’s going on I immediately changed DNS servers to something reliable. Before I did I found a tiny “about this page” link at the bottom of the heinous Optus search results page, where I was told how great this was for me, but how I could opt out of their “default” search engine if I wanted to but was warned this was an “advanced setting”.

Seriously, what do Optus think they’re doing? From a commercial standpoint, do they really think that their captive audience matters to anyone advertising on the web? Of course not, but in the mean time they’re certainly going to alienate customers who just maybe actually do want to use (in this case) Google sites.

There’s a bigger issue, though. Unaltered answers to DNS queries is a backbone of net neutrality. That’s our problem, but once carriers start poisoning nameservers in their own favour it will be but a blink before everyone is doing it to each other and lookups will become worthless. While I’m sure the morons in Marketing who thought that sabotaging DNS queries would be a good idea won’t be worried about the wreckage that will cause for everyone else, such a war wouldn’t be good for any of the companies involved, either. And meanwhile, if they really want everyone to learn how to install an app to “fix” the internet…

Of course, this is only a taste of what we’ll be in for when the communications minister finally gets his compulsory Great Firewall of Australia censorship in place, but one thing at a time. If you’re looking for internet access down here, clearly Optus or anything that uses their network should be blacklisted.

AfC

Haskell has been around for quite a while; somehow I had it in my head that it was outdated and only for computer science work. After all, there are always crazy weirdos out there in academia working on obscure research languages — at least, that’s the perspective from industry. After all, we’re the ones getting real work done. All you’re doing is sequencing the human genome. We invented Java 2 Enterprise Edition. Take that, ivory tower.

The newness bias is strong, which is why I was poleaxed to find people I respect like Erik de Castro Lopo and Conrad Parker working hard in, of all things, Haskell. And now they’re encouraging me to program in it, too (surely, cats and dogs are sleeping together this night). On their recommendation I’ve been learning a bit, and much to my surprise, it turns out Haskell is vibrant, improving, and really cutting edge.

The next thing

I get the impression that people are tired of being told that the some cool new thing makes everything else they’ve been doing irrelevant. Yet many professional programmers (and worse, fanboy script kiddies) are always looking to the next big thing, the next cool language. Often the very people you respect about a topic have already moved on to something else (there’s a book deal in it for them if they can write it fast enough).

But still; technology is constantly changing and there’s always pressure to be doing the latest and greatest. I try my best to resist this sort of thing, just in the interest of actually getting anything done. Not always easy, and the opposite trap is to adopt a bunker mentality whereby you defend what you’re doing against all comers. Not much learning going on there either.

There is, however, a difference between the latest new thing and learning something new.

One of the best things about being active in open source is the opportunity to meet people who you can look up to and learn from. I may know a thing or two about operations and crisis and such, but my techie friends and colleagues are my mentors when it comes to software development and computer engineering. One thing they have taught me over the years is the value of setting out deliberately to “stretch” your mind. Specifically, experimenting with a new programming language that is not your day-to-day working environment, but something that will force your to learn new ways of looking at problems. These guys are professionals; they recognize that whatever your working language(s) are, you’re going to keep using them because you get things done there. It’s not about being seduced by the latest cool project that some popular blogger would have you believe is the be-all-and-end-all. Rather, in stretching, you might be able to bring ideas back to your main work and just might improve thereby. I think there is wisdom there.

Should I attempt to learn Haskell?

I’ve had an eye on functional programming for a while now; who hasn’t? Not being from a formal computer science or mathematics background — (“damnit Jim, I’m an engineer, not an english major” when called upon to defend my atrocious spelling) — the whole “omigod, like, everything is function and that’s like, totally cool” mantra isn’t quite as compelling by itself as it might be. But lots of people I respect have been going on about functional programming for a while now, and it seemed a good direction to stretch. So I asked which language should I learn?

My colleagues suggested Haskell for a number of reasons. That cutting edge research was happening there and that increasingly powerful things were being implemented in the compiler and runtime as a result sounded interesting. That Haskell being a pure functional language (I didn’t know yet what that meant but that’s beside the point) would really force me to learn a functional way of doing at things (as opposed to some others where you can do functional things but can easily escape those constraints; pragmatic, perhaps, but since the idea was to learn something new, that made Haskell sound good rather than perceiving this as a limitation). Finally, they claimed that you could express problems concisely (brevity good, though not if it’s so dense that it’s write-only).

Considering a new language (or, within a language, considering various competing frameworks for web applications, graphical user interface, production deployment, etc) my sense is that when we look at such things we are all fairly quick to judge, based on our own private aesthetic. Does it look clean? Can I do things I need to do with this easily? How do the authors conceive of the problem space? (in web programming especially, a given framework will make some things easy and other things nigh on impossible; you need to know what world-view you’re buying into).

I don’t know about you, but elegance by itself and in the abstract is not sufficient. Elegance is probably the most highly valued characteristic of good engineering design, but it must be coupled with practicality. In other words, does the design get the job done? So before I was willing to invest time learning Haskell, I wanted to at least have some idea that I’d be able to use it for something more than just academic curiosity.

Incidentally, I’m not sure the Haskell community does itself many favours by glorifying in how clever you can be in the language; the implied corollary is that you can’t do anything without being exceedingly clever about it. If true, that would be tedious. I get the humour of the commentary that as we gain experience we tend to overcomplicate things, as seen in the many different ways there are to express a factorial function. But I saw that article linked from almost every thread about how clever you can be with Haskell; is that the sort of thing that you want to use as an introduction for newcomers? Given the syntax is so different from what people are used to in mainstream C-derived programming languages, the code there just looks like mush. The fact that there are people who studied mathematics are doing theorem proving in the language is fascinating, but the tone is very elevated as a result. A high bar for a newcomer — even a professional with 25 years programming experience — to face.

It became clear pretty fast that I wouldn’t have the faintest idea what I was looking at, but I still tried to see if I could get a sense of what using Haskell would be like. Search on phrases like “haskell performance”, “haskell in production”, “commercial use of haskell”, “haskell vs scala”, and so on. You get more than enough highly partisan discussion. It’s quick to see people love the language. It’s a little harder to evidence see it being used in anger, but eventually I came across pages like Haskell in Industry and Haskell Weekly News which have lots of interesting links. That pretty much convinced me it’d be worth giving it a go.

A brief introduction

So here I am, struggling away learning Haskell. I guess I’d have to say I’m still a bit dubious, but the wonderful beginner tutorial called Learn You A Haskell For Great Good (No Starch Press) has cute illustrations. :) The other major starting point is Real World Haskell (O’Reilly). You can flip through it online as well, but really, once you get the idea, I think you’ll agree it’s worth having both in hard copy.

Somewhere along the way my investigations landed me on discussion of something called “software transactional memory” as an approach to concurrency. Having been a Java person for quite some years, I’m quite comfortable with multi-threading [and exceptionally tired of the rants from people who insist that you should only write single threaded programs], but I’m also aware that concurrency can be hard to get right and that solving bugs can be nasty. The idea of applying the database notion of transactions to memory access is fascinating. Reading about STM led me to this (short, language agnostic) keynote given at OSCON 2007 by one Simon Peyton-Jones, an engaging speaker and one of the original authors of GHC. Watching the video, I heard him mention that he had done an “introduction to Haskell” earlier in the conference. Huh. Sure enough, linked from here, are his slides and the video they took.

Watching the tutorial implies a non-trivial investment in time, and a bit of care to manually track the slides with him as he is presenting, but viewing it all the way through was a very rewarding experience. By the time I watched this I’d already read Learn You A Haskell and a goodly chunk of Real World Haskell, but if anything that made it even more fascinating; I suppose I was able to concentrate more on what he was saying for the emphasis on why things in Haskell are the way they were.

I was quite looking forward to how he would introduce I/O to an audience of beginners; like every other neophyte I’m grinding through learning what “monads” are and how they enable pure functional programming to coexist with side effects. Peyton-Jones’s discussion of IO turns up towards the end (part 2 at :54:36), when this definition went up on a slide:

IO (a) :: World -> (a, World)

accompanied by this description:

“You can think of it as a function that takes a World to a pair of a and a new World … a rather egocentric functional programmer’s view of things in which your function is center of the universe, and the entire world sort of goes in one side of your function, gets modified a bit by your function, and emerges, in a purely functional way, in a freshly minted world which comes out the other…”

“Oh, so that’s a metaphor?” asked one of his audience.

“Yes. The world does not actually disappear into your laptop. But you can think of it that way if you like.”

Ha. :)

Isolation and reusability

A moment ago I mentioned practicality. The most practical thing going these days is the web problem, i.e. using a language and its toolchain to do web programming. Ok, so what web frameworks are there for Haskell? Turns out there are a few. Two newer ones in particular, Yesod and the Snap Framework. Their raw performance as web servers looks very impressive, but the real question is how does writing web pages & application logic go down? Yesod’s approach, called “Hamlet“, doesn’t do much for me. I can see why type safety across the various pieces making up a web page would be something you’d aspire to, but it ain’t happening (expecting designers to embed their work in a pseudo-but-not-actually HTML language has been tried before. Frequently. And it’s been a bust every time). Snap, on the other hand, has something called “Heist“. Templates are pure HTML and when you need to drop in programmatically generated snippets you do so with a custom tag that gets substituted in at runtime. That’s alright. As for writing said markup from within code there’s a different project called “Blaze” which looks easy enough to use.

Reading a thread about Haskell web programming, I saw explicit acknowledgement on the part of framework authors from all sides that it would be possible to mix and match, at least in theory. If you like Yesod’s web server but would rather to use Snap’s Heist template engine, you could probably do so. You’d be in for all the glue code and knowing what you’re about, but this still raises an interesting point.

A big deal with Haskell — and one of the core premises of programming in a functional language that emphasizes purity and modularity — is that you can rely on code from other libraries not to interfere with your code. It’s more than just “no global variables”; pure functions are self contained, and when there are side effects (as captured in IO and other monads) they are explicitly marked and segregated from pure code. In IT we’ve talked about reusable code for a long time, and we’ve all struggled with it: the sad reality is that in most languages, when you call something you have few guarantees that nothing else is going to happen over and above what you’ve asked for. The notion of a language and its runtime explicitly going out of its way to inhibit this sort of thing is appealing.

Hello web, er world

Grandiose notions aside, I wanted to see if I could write something that felt “clean”, even if I’m not yet proficient in the language. I mentioned above that I liked the look of Snap. So, I roughed out some simple exercises of what using the basic API would be like. The fact that I am brand new at Haskell of course meant it took a lot longer than it should have! That’s ok, I learnt a few things along the way. I’ll probably blog separately about it, but after an essay about elegance and pragmatism, I thought I should close with some code. The program is just a little ditty that echos your HTTP request headers back to you, running there. You can decide for yourself if the source is aesthetically pleasing; ’tis a personal matter. I think it’s ok, though I’m not for a moment saying that it’s “good” style or anything. I will say that with Haskell I’ve already noticed that what looks deceptively simple often takes a lot of futzing to get the types right — but I’ve also noticed that when something does finally compile, it tends to be very close to being done. Huh.

So here I am freely admitting that I was quite wrong about Haskell. It’s been a bit of a struggle getting started, and I’m still a bit sceptical about the syntax, but I think the idea of leveraging Haskell shows promise, especially for server-side work.

AfC

Sure, it’s different than GNOME 2. It’s vastly different. But it is a new UI paradigm. The GNOME 2 experience was over 9 years old, and largely based on the experience inherited from the old Windows 95 muxed with a bit of CDE. There were so many things that the GNOME hackers wanted to do — and lots of things all the UI studies said needed changing — that the old pattern simply couldn’t support.

Still, a lot of people are upset. Surprise. Most recently it’s been people running Debian Testing who just recently found that their distro has migrated its packages from GNOME 2.32 to GNOME 3.x. Distros like Ubuntu have been shipping GNOME 2.32 for ages; but it has been well over 2 years since anyone actually worked on that code. It’s wonderful that nothing has changed for you in all that time [a true Debian Stable experience!] but I think it’s a bit odd not to expect that something that was widely advertised as being such a different user experience is … different.

What I find annoying about these conversations is that if they had gone and bought an Apple laptop with Mac OS X on it they would be perfectly reasonably working through learning how to use a new Desktop and not complaining about it at all. But here we are admonishing the GNOME hackers had the temerity to do something new and different.

Installing

I went to some trouble to run GNOME 3 on Ubuntu Linux during the Natty cycle; that was a bit of work but I needed to be current; now with Oneiric things are mostly up to date. GNOME 3.0 was indeed a bit of a mess, but then so was GNOME 2.0. The recently released 3.2 is a big improvement. And it looks like the list of things that seem targeted to 3.4 will further improve things.

I’m now running GNOME 3 on a freshly built Ubuntu Oneiric system; I just did a “command line” install of Ubuntu and then installed gdm, gnome-shell, xserver-xorg and friends. Working great, and not having installed gnome-desktop saved me a huge amount of baggage. Of course a normal Oneiric desktop install and then similarly installing and switching to gnome-shell would work fine too; either way you probably want to enable the ppa:gnome3-team/gnome3 PPA.

Launchers

One thing I do recommend is mapping (say) CapsLock as an additional “Hyper” and then Caps + F1 .. Caps + F12 as launchers. I have epiphany browser on F1, evolution on F2, my IRC client on F3 and so on. Setting up Caps + A as to do gnome-terminal --window means you can pop a term easily from anywhere. You do the mapping in:

    System Settings → Keyboard Layout → Layout tab → Options...

and can set up launchers via:

    System Settings → Keyboard → Shortcuts tab → "Custom Shortcuts" → `[+]` button

(you’d think that’d all just be in one capplet, but anyway)

Not that my choices matter, per se, but to gives you an idea:

That means I only use the Overview’s lookup mechanism (ie typing Win, T, R, A… in this case looking for the Project Hamster time tracker) for outlying applications. The rest of the time it’s Caps + F12 and bang, I’ve got GEdit in front of me.

Of course you can also set up the things you use the most on the “Dash” (I think that’s what they call it) as favourites. I’ve actually stopped doing that (I gather the original design didn’t have favourites at all); I prefer to have it as an alternative view of things that are actually running.

Extensions

People love plugin architectures, but they’re quite the anti-pattern; over and above the software maintenance headache (evolving upstream constantly breaks APIs used by plugins, for one example; the nightmare of packaging plugins safely being another) before long you get people installing things with contradictory behaviour and which completely trash the whole experience that your program was designed to have in the first place.

Case in point is that it didn’t take long after people discovered how to use the extension mechanism built into gnome-shell for people to start using it to implement … GNOME 2. Gawd.

Seeking that certainly is not my recommendation; as I wrote above the point of GNOME 3 and it’s new shell is to enable a new mode of interaction. Still, everyone has got their itches and annoyances, and so for my friends who can’t live without their GNOME 2 features, I thought I’d point out a few things.

There are a collections of GNOME Shell Extensions some of which appear to be packaged, i.e. gnome-shell-extensions-drive-menu for an plugin which gives you some kind of menu when removable devices are inserted. I’m not quite sure what the point of that is; the shell already puts something in the tray when you’ve got removable media. Whatever floats your boat, I guess. Out in the wild are a bunch more. The charmingly named GNOME Shell Frippery extensions by Ron Yorston has a bunch of plugins to recreate GNOME 2 features. Most are things I wouldn’t touch with a ten-foot pole (a bottom panel? Who needs it? Yo, hit the Win key to activate the Overview and you see everything!).

My personal itch was wanting to have 4 fixed workspaces. The “Auto Move Workspaces” plugin from gnome-shell-extensions was close (and would be interesting if its experience and UI were properly integrated into the primary shell experience), but the “Static Workspaces” plugin from gnome-shell-frippery did exactly the trick. Now I have four fixed workspaces and I can get to them with Caps + 1 .. Caps + 4. Hurrah.

You install the plugin by dropping the Static_Workspaces@rmy.pobox.com/ directory into ~/.local/share/gnome-shell/extensions/, then restarting the Shell via Alt + F2, R, and then firing up gnome-tweak-tool and activating the extension:

    Advanced Settings → Shell Extension tab → switch "Static Workspaces Extension" to "On"

Hopefully someone will Debian package gnome-shell-frippery soon.

Not quite properly integrated

Having to create custom launchers and fiddle around with plugins just to get things working? “Properly integrated” this ain’t, and that’s my fault. I respect the team hacking on GNOME 3, and I know they’re working hard to create a solid experience. I feel dirty having to poke and tear their work apart. Hopefully over the next few release cycles things like this will be pulled into the core and given the polish and refined experience that have always been what we’ve tried to achieve in GNOME. What would be really brilliant, though, would be a way to capture and export these customizations. Especially launchers; setting that up on new machines is a pain and it’d be lovely to be able to make it happen via a package. Hm.

AfC

 Error trying to connect to remote server: net.au (DNS lookup: net.au:5269)

in the logs. Took a while to isolate that (Java stack traces in server logs, how I hate thee), but that led me to this discussion about the problem.

Turns out to be, more or less, this issue.

Back to the original thread, comment by Gordon Messmer turns the trick; he isolated the specific problem and provided a patch which you can reverse apply. Since I had already downloaded the 3.7.1 nightly build .deb and installed it (which did not fix the problem), but with a patch in hand, I was then able to follow the advice of “Devil” to rebuild the server and replace the openfire.jar manually.

Obviously I will rebuild the .deb in question shortly, but I can confirm that reverting that specific change does restore server to server functionality with people you used to be able to connect to fine.

Meanwhile 3.7.1, alpha though it may be, does seem to have a fair few fixes in it. We’ll keep that for now.

AfC

Found a number of references to using losetup but wanted something simpler; doing the loop part automatically has been a “take for granted” thing for years.

It turns out that if your image is in kvm-img‘s “raw” format already then you can pretty much access it directly. We found this article, dated 2009, which shows you can do it pretty quickly; assuming that the partition is the first (or only one) in the disk image:

# mount -o ro,loop,offset=32256 dwarf.raw /mnt
#

which does work!

I’m a bit unclear about the offset number; where did that come from?

An earlier post mentioned something called kpartx. Given a disk, it will identify partitions and make them available as devices in via the device mapper. Neat. Hadn’t run into that one before.

This comment on Linux Questions suggested using kpartx directly as follows:

# kpartx -a dwarf.raw 
# mount -o ro /dev/mapper/loop0p1 /mnt
#

Nice.

Incidentally, later in that thread is mention of how to calculate offsets using sfdisk -l, however that doesn’t help if you don’t already have the disk available in /dev. But you can use the very same kpartx to get the number of cylinders:

# kpartx -l dwarf.raw 
loop0p1 : 0 16777089 /dev/loop0 63
#

Ah ha; 63 sectors × 512 byte block size is 32256. So now we know where they got the number from; adjust your own mounts accordingly. :)

AfC

Comments:

1. Pádraig Brady wrote in, saying “I find partx is overkill. I’ve been using the following script for years; lomount.sh dwarf.raw 1 /mnt is how you might use it.” Interesting use of fdisk, there.

I noticed gnome-icon-theme was one of the packages that bumped. It turns out that package is now only a limited subset of the GNOME icon set and that you have to install gnome-icon-theme-full to get the icons you actually need. Bah², but now everything is back the way it should be.

AfC

One massive gotcha: the post bodies are sanitized on import so if you’re using something like Markdown for formatting you get a real mess when it “helpfully” converts > characters to HTML entities, swallows URLs properly enclosed in <>, etc. There is a workaround, thankfully:

#
# The WordPress post function sanitizes all input, and this
# includes escaping bare '>' characters to HTML entities.
# This is most unhelpful when importing Markdown data.
#

    kses_remove_filters();

and then you can safely call insert without your content getting munged:

#
# Construct post and add.
#

    $post = array(
            'post_title' => $title,
            'post_name' => $slug,
            'post_content' => $content,
            'post_category' => array($category),
            'post_date' => $date,
            'post_status' => "publish",
            'post_author' => 2,
    );      

    $result = wp_insert_post($post), true);

    if (is_wp_error($result)) {
            echo "ERROR\n";
            echo print_r($result);
    } else {
            echo "New post ID: $result\n";
    }

etc.

Like I said, it’s a royal pita to figure out the category ID; you need to use the raw ID numbers from the database, not symbolic names or slugs. Ugh.

My blog’s RSS feed is now http://blogs.operationaldynamics.com/andrew/feed. I did my best to preserve post times, guids, etc, but there came a point where it just wasn’t going to get any closer; sorry if you get dups in your reader or planet.

Incidentally, what we all knew as “WordPress MU” is now called a “Network Install”. Go figure, but if you need multi-site aka multi-blog aka multi-user installation you really need to read “Create A Network” for instructions. Do this setup before creating (or importing) content unless you want the joy and bliss of reinstalling several times.

AfC

This post is an extract of the release note from the NEWS file which you can read online … or in the sources from Bazaar.

java-gnome 4.1.1 (11 Jul 2011)

To bump or not to bump; that is the question

This is the first release in the 4.1 series. This introduces coverage of the GNOME 3 series of libraries, notably GTK 3.0. There was a fairly significant API change from GTK 2.x to 3.x, and we’ve done our best to accommodate it.

Drawing with Cairo, which you were already doing

The biggest change has to do with drawing; if you have a custom widget (ie, a DrawingArea) then you have to put your Cairo drawing code in a handler for the Widget.Draw signal rather than what used to be Widget.ExposeEvent. Since java-gnome has ever only exposed drawing via Cairo, this change will be transparent to most developers using the library.

Other significant changes include colours: instead of the former Color class there’s now RGBA; you use this in calls in the override...() family instead of modify...() family; for example see Widget’s overrideColor().

Orientation is allowed now

Widgets that had abstract base classes and then concrete horizontal and vertical subclasses can now all be instantiated directly with an Orientable parameter. The most notable example is Box’s <init>() (the idea is to replace VBox and HBox, which upstream is going to do away with). Others are Paned, various Range subclasses such as Scrollbar. Separator, Toolbar, and ProgressBar now implement Orientable as well.

There’s actually a new layout Container, however. Replacing Box and Table is Grid. Grid is optimized for GTK’s new height-for-width geometry management and should be used in preference to other Containers.

The ComboBox API was rearranged somewhat. The text-only type is now ComboBoxText; the former ComboBoxEntry is gone and replaced by a ComboBox property. This is somewhat counter-intuitive since the behaviour of the Widget is so dramatically different when in this mode (ie, it looks like a ComboBoxEntry; funny, that).

Other improvements

It’s been some months since our last release, and although most of the work has focused on refactoring to present GTK 3.0, there have been numerous other improvements. Cairo in particular has seen some refinement in the area of Pattern and Filter handling thanks to Will Temperley, and coverage of additional TextView and TextTag properties, notably relating to paragraph spacing and padding.

Thanks to Kenneth Prugh, Serkan Kaba, and Guillaume Mazoyer for their help porting java-gnome to GNOME 3.

You can download java-gnome’s sources from ftp.gnome.org, or easily checkout a branch from ‘mainline‘:

$ bzr checkout bzr://research.operationaldynamics.com/bzr/java-gnome/mainline java-gnome

though if you’re going to do that you’re best off following the instructions in the HACKING guidelines.

AfC

This post is an extract of the release note from the NEWS file which you can read online.

java-gnome 4.0.20 (11 Jul 2011)

This will be the last release in the 4.0 series. It is meant only as an aide to porting over the API bump between 4.0 and 4.1; if your code builds against 4.0.20 without reference to any deprecated classes or methods then you can be fairly certain it will build against 4.1.1 when you finally get a system that has GTK 3.0 and the other GNOME 3 libraries on it.

AfC