2013-07-30

Heading to Brno

Just in the airport, about to fly from Toronto, Canada, to Prague and then catch a bus to Brno.



Two things I thought I'd note:


  • It's going to be very warm/quite hot in Brno for the next 10 days
    The Weather Network  Temperatures above 30°C and little chance of rain.

  • Student Agency, http://www.studentagencybus.com/, has very inexpensive bus fares from Prague to Brno.  $10CAD (2400HUF).  Whee!


2013-07-28

GXml: Summer of broken API

Welcome back to the wonderful world of GXml.  Here's an update on progress so far.  (Also, thanks to Daniel Espinosa and Adam Ples for recent contributions to serialisation, XPath support, and bug fixes.)


Code


For those interested in the code so far, it's in its own branch thanks to the abundant API breakage (detailed below): 

https://git.gnome.org/browse/gxml/log/?h=gsoc2013



My plan is to release another in the 0.3.x series without major API breakage, and then release 0.4 soon (during GUADEC) with the major API changes.


GUADEC


Thanks to sponsorship from the GNOME foundation, GXml is going to Brno!  In previous years, I've gotten to know some of you.  This year, I'm going to bug you about your code and, if you use GXml, find out what will get you to use GXml. :D


Memory Magic



Changing models


Before, when you obtained a reference to a node from GXml, you owned it and had to unref it.  However, with GXml, nodes are only really useful while their document exists (which manages things like attribute synchronisation with the underlying libxml2 structures).  Consequently, and to simplify reference handling for users, a GXml document alone now owns references to its nodes, and is entirely responsible for freeing its memory.  All a user of the library must do is unref their GXmlDocument when they're done with it.


Valgrind


Valgrind was used to identify memory leaks, where we failed to free libxml2 data or where we created reference cycles.  I'm hoping to write a useful guide on using valgrind later.  It required a lot of suppression file writing and testing, too, to determine which memory from glib and libxml2 could be released by a user, and which couldn't.


Tests


We have a collection of small valgrind tests now so it should be harder to introduce new memory leaks in the future.


API Chaos



DOM spec compliance: GXmlNode


Formerly, XML nodes were called GXmlDomNode.  That was to avoid namespace conflict in languages where Node could mean GLib.Node or GXml.Node.  However, that meant a lot of extra characters in C.  Since I started using DomNode, it's also grated on me, especially because it's not the name known to the DOM spec.  Consequently, pursuant to earlier blog posts and IRC discussions on the matter, it's now GXmlNode.  Dun dun dun!



Attribute might become Attr and Implementation might become DomImplementation, and DocumentType might become DocType.  Feel free to comment on your thoughts on those compliance questions.  I don't want to change entity names again the future.


Error Reporting Revolution


Regarding an earlier discussion, GXml has been misusing GError just because try-catch exception handling is addictive.  Ultimately, after some discussions and analysis, we've switched from GErrors to issuing g_warnings (and having a last_error variable a user can check after running a function if they're unsure of their code's correctness).



Also, all but one DOMException from the DOM Level 1 Core is now tested for!  (Before, only a few actually were.)  The one that isn't so far is whether a node is readonly, since GXml doesn't have a concept of read-only nodes yet. :)


Educational Euphoria



Documentation


Every property and function should now include a reference to its definition in the DOM Level 1 Core spec.  It should also specify the version of the spec the property or function complies with, so that when we move towards Level 2, etc., you can know what to expect.


Examples


More examples exist under examples/c and examples/js now, and there'll be more to come.


Gritty Reality


Writing test patches for projects like yelp, glade, dconf, and libgdata has helped identify a few bugs or failings in the API which have been fixed.  If you're working on those projects and wonder why you haven't seen a patch yet, it's because they're in flux and need to be re-written once I stop changing the API above. :D


A bold new future


Going forward, there's still a lot to do.  Finalise the API, integrate patches accumulating in bugzilla and in branches (XPath support courtesy Adam Ples?!), serialization update (courtesy of Daniel Espinoza) and measure performance.

2013-07-24

[Technology] Firefox, libraries, and architectures

So, my laptop is unusable at present, so I'm trying to use school computers.  Trying to check my e-mail (GMail, which gets my University e-mails), I am told that the installed browser (Ice Weasel) is 'too old'.  OK, so I'll just locally install a newer Firefox.




$ firefox
XPCOMGlueLoad error for file ~/.local/opt/firefox/libxul.so:
libdbus-glib-1.so.2: cannot open shared object file: No such file or directory
Couldn't load XPCOM.



I double check, and indeed, libdbus-glib-1.so.2 is in /usr/lib/.



Running


$ LD_DEBUG=libs firefox


prints out, among other things, the search path it uses, and confirms that Firefox's website provided me with a 32-bit binary, expecting 32-bit libraries, on a system that does not have many 32-bit libraries. :D  Not even 'LD_LIBRARY_PATH=/usr/lib firefox' can save me now.



Annoyingly, Firefox's website doesn't seem to offer an easy way to choose which architecture (beyond the OS and language) you want, so I just went here:



http://releases.mozilla.org/pub/mozilla.org/firefox/releases/latest/linux-x86_64/en-US/



And voila!



2013-07-05

[Technology] gtk-doc failing to load chunk.xsl

While working on GXml, trying to generate its documentation, I ran into this:



I/O error : Attempt to load network entity http://docbook.sourceforge.net/release/xsl/current/html/chunk.xsl
warning: failed to load external entity "http://docbook.sourceforge.net/release/xsl/current/html/chunk.xsl"
compilation error: file /usr/share/gtk-doc/data/gtk-doc.xsl line 10 element import
xsl:import : unable to load http://docbook.sourceforge.net/release/xsl/current/html/chunk.xsl



This was not happening last week, so it must be my upgrade to Fedora 19.  I tried a few different things, and ultimately discovered RedHat bug 428531 which helpfully suggested reinstalling docbook-style-xsl. 



So, on Fedora,

yum reinstall docbook-style-xsl



After that, it finally continued and finished building. :)

[Technology] Valadoc not working in Fedora 19

While working on GXml, I ran into a problem, but then I fixed it, and life is good.



Valadoc failed to run earlier.  It was complaining about missing something like libgraph.so.25.  I'm not sure what the specific version number was now, but checking my system, I didn't have a libgraph.so anywhere.



When I tried to recompile valadoc, it returned errors like
"charts/chart.c:527:2: error: too few arguments to function 'aginit'"


Checking chart.c, I realised that this all has to do with libgvc, the GraphViz C library.  Version 2.30 breaks API with 2.28.  Fedora 18 shipped 2.28.  Fedora 19 ships 2.30 now, and I just upgraded to Fedora 19.



After chasing errors and reading documentations and sometimes source code, bug 703688 was born, and includes rough patches that fix it on my system.  Yay.

2013-07-04

[Technology] Fedora 19

Here's my laptop


  • Intel Core 2 Duo at 2.00GHz. 

  • Intel 945GM

  • 2GB RAM


Summary



First, I'd like to say I'm grateful for all the amazing work the designers and developers have put in to Fedora 19 and into GNOME 3.8.  That said, a lot of the things I noticed were things going wrong. 


  • FedUp's follow-up grub2-install (as instructed by Fedora's documentation) encountered a catastrophic grub error, and weirdness with its assistants, and some yum/rpm weirdness. 

  • GNOME Shell has a variety of little bugs (wallpaper, jerkiness, message tray responsiveness, painful design decisions)

  • I can no longer run "GNOME" when using dual-monitors :(

  • new applications have a blank look and aren't very useful yet (e.g. Timers and Alarms stop if you close the window; Weather couldn't find any cities)

  • GNOME Online Accounts still doesn't work with 2-factor authentication for Google (Contacts and Documents are noticeably less useful) (UPDATE: workaround does work, though I had to try it 3 times)

  • Tracker is finally usable on my system! :D  I can finally search for files!


I've also put in red the worst problems, and in green the greatest delights.  I'll be linking or submitting bugs when I have time over the next month.  I still look forward to a future where there's a QA process that can leave me confident in recommending Fedora (or any Linux) to friends.


FedUp Upgrade


Mostly straightforward.


  • look forward to a UI in the future, so I wouldn't have to tell normal friends to open the command-line. 

  • look forward to when the work of yum distro-sync will be handled by FedUp

  • look forward to when the work of grub2-install will be handled by FedUp (and won't break)

  • I really enjoyed the GNOME Help video and stuff.


Here are things I noticed


  • Following the instructions from the Fedora Documentation manual, I ran grub2-install and it gave me errors. 


    • /usr/sbin/grub2-bios-setup: warning: the device.map entry `hd0,1' is invalid. Ignoring it. Please correct or delete your device.map.
      /usr/sbin/grub2-bios-setup: warning: File system `ext2' doesn't support embedding.
      /usr/sbin/grub2-bios-setup: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged..
      /usr/sbin/grub2-bios-setup: error: will not proceed with blocklists

    • Rebooting led to the terrifying grub_rescue> prompt, and was not able to boot.

    • I booted with a LiveCD, mounted my HD, chroot, and re-ran grub2-install.


  • FedUp doesn't do anything for new applications like GNOME Clocks.  I used yum with the grouplist, groupinfo and groupupdate commands to identify new, interesting software and ensure it got installed.

  • Some libraries were missing or the wrong version, so consequently emacs wouldn't start ("emacs: error while loading shared libraries: libgnutls.so.26: cannot open shared object file: No such file or directory"), and this was fixed by yum distro-sync.

  • Setup assistants didn't start properly.


    • After my first reboot, there was no assistant. 

    • After my second reboot, after logging in, I had a session-specific assistant which lost my previous keyboard layouts (English, International; English, Dvorak; and Greek (symbols, yay!))


      • It asked to connect to my router, but no matter which nearby router I clicked on, it always prompted me for the password for the last one in the list (which was not mine); thankfully, the networking menu in the top bar worked.

      • It launches GNOME Help which has sexy videos; however, some of the videos have captions, whose # of lines change, and keep jerking the video up and down.  (See below for more complaints about one UI element altering the spatial position of others.)


    • After the third reboot, a system-wide assistant started, and asked me to create a new user; I didn't want to, so I didn't, and the assistant went away. 


  • On a secondary machine, I ran into an issue where yum update and stuff would not work, complaining about RPM errors.  I used rpm --rebuilddb and they went away.


    • This machine I did not do grub2-install and so it booted fine.

    • The setup assistants might have appeared when they were supposed to this time




Shell and Desktop



  • I like having a right-click to change the wallpaper (is that new to GNOME 3.8?)

  • I like some of the new animations

  • I like the larger window thumbnails in the activity overview

  • File Search is pretty usable!  Thanks to the fact that Tracker is almost usable on my system now (it has historically consumed ridiculous amounts of IO and CPU; it's still not perfect, if you look at Tracker below)

  • The volume change overlay (when I use media keys) nicely animates the increase and decrease in volume now.  Neat.


Problems


  • I'm not sure what exactly controls the wallpaper now, but a number of my wallpapers won't load.  I used to use Mirror (that's the one with the water and mountains in the distance) and it's still there and the path is set correctly (in org.gnome.desktop.background picture-uri) but nothing appears.   Also, adwaita-timed doesn't work either.  However, the new schroedinger-cat one works, and so do a number of others.

  • The login transition is jerky.  Probably my video card.

  • When at the lock screen, the icons in the top right (volume, wifi, power) group tightly together, and clicking any of them only brings up the volume control.  (This happened in GNOME 3.6 as well.)

  • Activities' list of applications seems to have lost categories.  This reduces discoverability and makes finding things very onerous.  I can search for things that I anticipate existing, but I can't be reminded of things I don't anticipate.


    • Apparently there are application groups but I can't find any UI with which to define them.


  • The Message Tray is hard to pull up now.  Before, it popped up too easily.  Basically, I can bring my mouse to the bottom and drag it down forever and nothing pops up, I have to start jerking it around and it's tiring and inconvenient.  Also, I used to think there was a hot corner in the bottom right to pull it up, but I suppose I was wrong (or it's gone).


    • The Message Tray is also invisible in Activities mode now (was it before?).  I didn't realise that messages had accumulated because I didn't realise that I wasn't getting it up at first.  Whoops.

    • I wonder what a user who doesn't already know that there's supposed to be a Message Tray would do; I can imagine them not discovering it for weeks/ever.

    • It still has that UI fault where one element modifies everything around it by pushing up my desktop rather than just climbing overtop it.  It's as bad as web pages and browsers that make a top message appear that pushes down all the web content, causing early mouse clicks to miss and misclick, or like Google Maps in my phone changing where the "Get Directions" button is after I've typed in locations, so I end up pressing the wrong thing.  I wish applications would stop affecting the spatial location of other things.


  • GNOME Classic uses OpenGL, apparently, because now I can't use GNOME at all with dual monitors.  OpenGL on the Intel 945GM has a 2000px width limit, and my screen becomes 1024+1920 pixels wide with a second monitor plugged in; so, now I have to log in with one screen, then use metacity to replace mutter.  I used to be able to add GNOME Panel as well, and I used to still have a wallpaper, but gnome-panel doesn't seem to be packaged any more, and I don't know who handles the wallpaper any more.  (Not nautilus, apparently.)



 Applications



  •  GNOME Weather exists as an application preview.  It has the same problem as a few other new ones where you open it and you just get a large grey window with nothing in it.  "What is this? What does it do?" Eventually I noticed the "New" button hiding in the corner, but it couldn't find any cities; I guess that's why it's a preview.


    • I look forward to when it will determine my local weather based on my IP address.


  • GNOME Clocks has the same problem as Weather, where you open it and there's ... nothing.  


    • Once you've manually defined some clocks, clicking on one enlarges the time and adds a minimum amount of new data (sunrise and sunset).  Unfortunately, it also loses the pretty picture.  So, right now, expanding a clock is almost pointless.  

    • I liked the Timer and Alarm sections.  However, if you close the GNOME Clocks window, those die.  So, unless I want the window open all the time, I cannot actually use the Alarm for anything.  

    • The application is might large (spatially) given what it works with.  It makes working with a Timer or an Alarm (or a clock) seem onerous.  It's information I think I'd want in my calendar drop down, instead.


  • GNOME Font Viewer isn't new, but I was actually missing it (didn't come through an upgrade at some point, apparently; hooray for manually going through yum group*)


    • Most fonts tell a prescribed story, but some show randomised gibberish; I wonder if it's a bug or not.


  • GNOME Contacts can't be tested for me until GNOME Online Accounts works with Google (see below) (UPDATE: a work around lets me connect again, yay) 


    • It's pretty slow and the window becomes unresponsive during most actions.

    • There are little popdowns after I do things like link contacts that don't disappear and instead wait for me to click an x, and instead of replacing one another, overlap. O_O

    • A lot of space is wasted with HUGE contact boxes in the list to the left, so you can only see about 6-7 people at a time.  Ugh; I should start calling this the Texan design fallacy.

    • Doesn't really indicate from which source each one comes; will fail to edit some and I am not allowed to understand why


  • Bijiben, I assume, is another preview application.  It seems a bit like GNote or Tomboy but wastes a bit more space; lots of basic features like hyperlinking and lists didn't seem to work yet despite having UI elements; lots of warnings on the terminal.

  • Nautilus 


    • has a LOVELY NEW TREE OPTION for list view


      • sadly, if you show the Place column for list view, a long path won't be shrunk/ellipsised, but the filename will, so I couldn't read files when I went a little deeper :(


    • File Search is almost usable (see Tracker below and GNOME Shell above)!  The main problem is that after you start a search, I/O is pillaged with "nautilus [nautilus-search]".  I think that might be them doing something like find and not them using Tracker, though. 


  • DevHelp


    • tops of pages are still obscured by the title of the section.


  • Rhythmbox is a little prettier.  


    • adding new music got weirder (maybe in GNOME 3.6); there's now an Import window and it lists tracks in directories it's checking, but the trick is, it's not actually adding them to your library yet.  It's now a two-stage thing, of tell it to find things, wait interminably for it to find them, and then click Add, and then click close.  I would have thought that Add would start the import process, and I wouldn't have to wait around for it to find results.  Tiresome.


  • Metacity didn't have keybindings set for alt-tabing between windows any more.  Perhaps this is related to new keybindings for Mutter/GNOME Shell that allow Super+tab to switch applications.  (I still use Metacity because Mutter's compositor using OpenGL can't handle a dual monitor setup with the Intel 945GM ;_;)



Settings 



  • Network Settings 


    • crashes when I was setting up a hot spot.

    • if I choose to forget a preferred network, the settings gear doesn't disappear immediately; if I click the gear, it crashes.


  • GNOME Online Accounts doesn't work with Google, at least when you're using two-factor authentication.  It apparently is blocked on OAuth2 support for CalDav which Google recently added and which e-d-s now needs to support.  There's apparently a workaround involving a one-time application-specific password from Google, which worked for me with GNOME 3.6, but doesn't in 3.8.


    • UPDATE: workaround still works


  • Tracker almost works!


    • tracker-file-miner no longer hammers my system all the time with persistent heavy IO!  It almost works as advertised.

    • it was also able to index my selected directories in 30 minutes, instead of indexing forever (I assume it must have been caught in some loop before)

    • sadly, there are an abundance of GDBus timeout errors in .xsession-errors from Tracker, concerning extraction of metadata from virtually everything

    • the next time I logged in, it took 40 seconds and iotop and top reported tracker-store was to blame







2013-07-03

[Technology] "error: symbol 'grub_term_highlight_color' not found."

I just upgraded from Fedora 18 to Fedora 19 and am a bit sad to run into a pretty horrific error when following the published upgrade instructions, again.



I consider this link to be the official upgrade instructions:

http://docs.fedoraproject.org/en-US/Fedora/19/html/Installation_Guide/ch18s02.html

That said, it's pretty hard to find.  Additionally, there are also these pages:

https://fedoraproject.org/wiki/FedUp

This next one is probably also useful, but incredibly more cryptic for a "normal" user:

https://fedoraproject.org/wiki/GRUB_2



So, despite having to use the command-line for FedUp (Anaconda doesn't work any more), FedUp itself ran pretty smoothly for me.  You'll note that the instructions tell you to update/reinstall grub.



After running the provided grub2-install command, I received the following warnings and errors:



/usr/sbin/grub2-bios-setup: warning: File system `ext2' doesn't support embedding.
/usr/sbin/grub2-bios-setup:
warning: Embedding is not possible.  GRUB can only be installed in this
setup by using blocklists.  However, blocklists are UNRELIABLE and
their use is discouraged..
/usr/sbin/grub2-bios-setup: error: will not proceed with blocklists






That sounds pretty alarming, but hey, if it didn't proceed, and then what could go wrong?  Reboot, and ...



error: symbol 'grub_term_highlight_color' not found.

grub_rescue>



Well, that's horrifying.



The best explanation of how to fix this (at least using a live USB key, if you have one handy, preferably from a recent Fedora (e.g. F19 itself :D)) that I found is this Ubuntu article:

https://help.ubuntu.com/community/Grub2/Installing#via_ChRoot

Particularly the section "via ChRoot".



Basically,


  • get to a command-line

  • mount your system's root partition somewhere (not /tmp)

  • mount special directories (see article)

  • mount your boot partition to /boot (if it's separate)

  • chroot into your system's root partition

  • run "grub2-install --recheck /dev/sda" (or wherever)

  • etc.


That fixed it for me.



Boot loader errors are terrifying for "regular" users, and it's sad that Fedora 19's instructions can lead to it.  Sigh.

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