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26 June 2012

Neil McGovern: Digital Economy Act And so it begins

Today, OFCOM issued a press release entitled "New measures to protect online copyright and inform consumers". According to the announcement, internet users will be encouraged to download music and films through legal channels under the measures. Ofcom has published a draft code for consultation that would require large internet service providers (ISPs) to inform customers of allegations that their internet connection has been used to infringe copyright. There does seem to have been a number of concessions made, which is welcome, but I do still have a number of concerns. The code 'only' covers ISPs with more than 400k fixed lines - BT, Everything Everywhere, O2, Sky, TalkTalk Group and Virgin Media. This covers about 93% of the UK retail market. If an allegation of copyright infringement is made, the ISP would need to write to the customer with notice that an infringement has occurred, and in a new change, the number of copyright infringement reports connected to their account. If more than three letters are received in a year, anonymous information may be provided on request to copyright owners showing them which infringement reports are linked to that customer s account. The copyright owner may then seek a court order requiring the ISP to reveal the identity of the customer. Two more changes have been implemented:

Copyright owners procedures for gathering evidence of infringement must now be approved by Ofcom, rather than by the copyright owners themselves.
Ofcom has decided that subscribers should have 20 working days to appeal an allegation of infringement, but only on grounds specified in the Digital Economy Act.

Obviously the former of these will require further scrutiny, but I'm happier that this is not with the vested interest themselves. As for the latter, this gets a bit interesting. The Act states that

an appeal on any grounds must be determined in favour of the subscriber unless the copyright owner or internet service provider shows that a) the apparent infringement was an infringement of copyright, and b) the report relates to the subscriber s IP address at the time of that infringement.

This is good as it puts the burden of proof on the copyright owner, although it still uses IP addresses which is problematic. For example, New York Judge Gary Brown has ruled IP addresses are insufficient evidence to identify pirates, and has provided a lengthy and thoughtful explanation in his ruling. There has also been a consultation published on the how to share costs costs. The suggestion is fairly simple:

"Copyright Owners should bear all of the costs incurred by Ofcom, the majority of costs incurred by the appeals body, and 75% of the costs efficiently and reasonably incurred by Qualifying ISPs in carrying out their obligations."

This has the risk of driving up internet access prices as ISPs have to recover the costs of these notifications. Additionally:

"Under the Order, subscribers will have to pay a 20 fee to make an appeal against a report of infringement, which will be refunded in the event the appeal succeeds; the remaining costs of determining an appeal will be met by the Copyright Owner who submitted the CIR which has been appealed."

I disagree with the concept of having to pay for an appeal in this way. If accused, someone should be able to refute the argument without cost. This will introduce a barrier to entry, and even if it is refundable is something I believe should be avoided. Finally, the exact costs of implementing this have been set out. It looks like the Copyright Owners would have to pay 60p per letter (with the ISPs shouldering the remaining 20p), a similar split around capital costs - which are the ones that are actually significant. Taking the above, it seems that in total that content owners will have to shell out 15M to use the DEA scheme. The cost seems to be more or less fixed which could encourage content owners to send out frivolous accusations. There's an iterative process which will run to determine the estimated number of notifications, and if eventually the Content Owners don't agree with the pricing, they will have elected not to take advantage of the provisions of the Initial Obligations Code, as they have not been able to make binding commitments to fund CIR processing. So, in summary, this is something to keep an eye on. It certainly hasn't gone away, it's due to start in March 2014. The revised draft code and consultation, which closes on 26 July 2012, can be found here, and the sharing of costs consultation runs until 18th September 2012, found here.

Russ Allbery: Review: Quiet

Review: Quiet, by Susan Cain

Publisher:	Crown
Copyright:	2012
ISBN:	0-307-45220-4
Format:	Kindle
Pages:	263

I've always been an introvert. This is something that surprises some people when they first meet me since they equate introversion with shyness, and I'm not at all shy. It surprises others because I'm quite vocal and outspoken in meetings, but introversion also doesn't imply a lack of self-confidence. I can run meetings, give presentations, and argue my perspective in front of just about anyone, but I don't like parties, I crave time by myself, and I could happily go for weeks without seeing another human being. I'm an introvert because I find people draining rather than invigorating, written communication far easier and more comfortable than spoken, and superficial social contact more irritating and frustrating than enjoyable. If you think think that means there may be something wrong with me, or that I would be happier if "drawn out of my shell," I wish you would read this book. But I suspect its core audience will be people like me: those who are tired of being pushed to conform with extrovert beliefs about social interaction, those who are deeply disgusted by the word "antisocial" or feel pangs of irrational guilt when hearing it, or those who just want to read an examination of interpersonal interactions that, for once, is written by and about people who like quiet and solitude just like they do. I first encountered Susan Cain via her TED talk, which I think is both the best possible summary of this book and the best advertisement for it. If you've not already seen it, watch it; it's one of the best TED talks I've seen, good enough that I've watched it three times. If you then want more of the same, buy Quiet. Quiet has, I think, three messages. First, it's a tour of the science: what is introversion and extroversion? Is there evidence that these are real physiological differences? (Spoiler: yes.) What do we know about introversion? How do we know those things what experiments have been done and what methods have been used? Here, it's a good general introduction, although Cain is careful to point out that it only scratches the surface and there's much more scientific depth. For example, she touches on the connections between introversion and sensitivity to stimulus and points out that they're two separate, if related, categorizations, but doesn't have the space here to clarify the distinctions and tease them apart. But she lays a reasonable foundation, particularly in defense of introversion as a natural, physiologically grounded, scientifically analyzable, common, and healthy way of interacting with the world. (For those who are curious about the distinctions between introversion and sensitivity, and the argument that most of what Cain says here about introversion is actually about sensitivity, see the blog post by Elaine Aron.) The second message, the one that resonated with me the most, was Cain's passionate defense of introversion. Business culture (at least in the United States, which is what both Cain and I know) is strongly biased towards extroversion; at least faking extroversion seems to be required for some career advancement. Extrovert culture dominates politics and most public discourse. It's common to find people who consider introversion, particularly in children, to be a sign of unhappiness, poor social adjustment, psychological problems, or other issues that should be "cured" or changed. Cain's gentle but firm passion in defense of introversion is a breath of fresh air. She attacks open plan offices, the current obsession with group learning and social school settings, and the modern group-think bias towards collaboration over solitude and concentration, and she does that with a combination of polite frustration and the conclusions of multiple studies. Introverts will be cheering as she constructs solid arguments and musters evidence against things that we've always found miserable and then been told we were wrong, short-sighted, or socially inept for finding miserable. I am so utterly on her side in this argument that I have no way of knowing how persuasive it will be, but it's lovely just to hear someone put into words what I feel. This defense does skew the book. Quiet is not, and does not purport to be, an even-handed presentation of introversion and extroversion. It's written proudly and unabashedly from the introvert's point of view. I'm fine with that: I, like Cain, think the US is saturated in extrovert perspectives and extrovert advice, particularly in the business world, and could use some balancing by activism from the other perspective. But be aware that this is not the book to look to for an objective study of all angles of the introvert/extrovert dichotomy, and I'm not sure her descriptions of extroversion are entirely fair or analogous to those of introversion. The extroversion described here seems somewhat extreme to me. I'm dubious how many extroverts would recognize themselves in it, which partly undermines the argument. The third message of the book, once Cain has won the introvert's heart, is some advice on how to be a proud introvert, to make the space and find the quiet that one desires, and to balance that against places where one may want and need to act like an extrovert for a while. Cain thankfully does not try to make this too much of the book, nor does she hold up any particular approach as The Answer. All the answers are going to be individual. But she does offer some food for thought, particularly around how to be conscious of and make delibrate choices about one's energy expenditures and one's recharge space. She also captures beautifully something that I've not seen explained this well before: the relief that an introvert can feel in the company of an extrovert who helps navigate social situations, make conversation, and keep discussions going until they can reach the depth and comfort level where the introvert can engage. I wish anyone in a position of authority over social situations would read this book, or at least watch the TED talk and be aware of the issues. Particularly managers, since (at least in my relatively limited experience) workplace culture is so far skewed towards extroversion that it can be toxic to introverts. Many of the techniques used by extrovert managers, and the goals and advice they give their employees, are simply wrong for introverts, and even damaging. Cain speaks well to the difficulties of empathy between people with very different interaction preferences, such as the problems with extroverts trying to "draw out" introverts who have hit social overload (or sensitive people who have hit stimulus overload). She also discusses something that I'd previously not thought about, namely how the pressure towards extroversion leads people to act extroverted even when naturally introverted, and how it's therefore very difficult to tell from behavior (and sometimes even to tell internally!) what one's natural interaction style is. But mostly I recommend this book if you're an introvert, if the TED talk linked above speaks to you. Even if we can't convince the world to respect introversion more, or at least stop treating it as abnormal, it's a lovely feeling to read a book from someone who gets it. Who understands. Who fills a book with great stories about introverts and how they construct their worlds and create quiet space in which to be themselves. Rating: 9 out of 10

25 June 2012

Raphaël Hertzog: Test Driven Development with CppUTest, now in Debian

I have recently read Test Driven Development with Embedded C by James W. Grenning and published by Pragmatic Programmers. I really enjoyed the book: while I was aware of the huge benefits of having a comprehensive test suite, I never studied seriously the principles behind Test Driven Development (TDD) and this book makes a good introduction to the topic. At the same time it focuses on the C language and contains lots of examples on how you can create tests even for projects which have to interact with hardware or other unpredictable components (the key is to create many abstractions) using all the possibilities that C offers. The author convincingly argues that developing code with TDD forces you to create a modular design that is easier to evolve when the underlying requirements change. He also highlights how the tests serve as reference documentation of the API. James W. Grenning recommends CppUTest as his xUnit test framework of choice. When I wanted to try this test framework, I discovered that it was not available in Debian. I decided to package it because it has some interesting features not offered by the contenders (at least not to my knowledge). It s now available in Debian and in Ubuntu. First, it doesn t require any explicit registration of tests and has a very lightweight syntax. The small downside is that CppUTest requires the usage of C++ for the tests. But C++ is compatible with C so it doesn t matter much if you have a C++ compiler for your target. On the contrary, usage of variables and methods scoped to the test group makes it easy to write clear tests. Here s a short sample of test code:

extern "C"  
#include "timer.h"
#include "timefn.h"
 
 
#include "CppUTest/TestHarness.h"
 
static Time the_time;
static const int start_sec = 123;
static const int start_nsec = 456789000;
static const int delay_sec = 8;
static const int delay_nsec = 111111000; // start_nsec + delay_nsec < 10^9
 
TEST_GROUP(Timer)
 
    /* Class variables available to all tests in the group */
    Timer timer;
    Delay remaining;
 
    /* Standard setup/teardown methods of xUnit tests */
    void setup()  
        timer = timer_new();
        time_set(&the_time, start_sec, start_nsec);
        /* [...] */
     
 
    void teardown()  
        timer_free(timer);
        /* [...] */
     
 
    /* Helper functions specific to the test group */
    void start_timer_with_delay(long sec, long nsec)
     
        timer_set_real_delay(timer, sec, nsec);
        timer_start(timer);
     
 
    void ensure_remaining_is(long sec, long nsec)
     
        CHECK_EQUAL(sec, delay_get_seconds(remaining));
        CHECK_EQUAL(nsec, delay_get_nanoseconds(remaining));
     
 ;
 
TEST(Timer, NewIsNotStarted)
 
    CHECK(!timer->started);
 
/* [...] */
TEST(Timer, GetRemainingTimeWithNanosecondPrecision_ShiftOfSeconds)
 
    start_timer_with_delay(delay_sec, delay_nsec);
    time_set(&the_time, start_sec + delay_sec - 5, start_nsec + delay_nsec + 1000);
 
    remaining = timer_get_remaining_time(timer);
 
    ensure_remaining_is(4, 999999000);

To run those tests, you just need this boilerplate code in a main.cpp:

#include "CppUTest/CommandLineTestRunner.h"
 
int main(int argc, char** argv)
 
   return CommandLineTestRunner::RunAllTests(argc, argv);

Another interesting feature is its integrated memory leak detection system. Any test that hasn t released allocated memory at the end of the teardown process will be marked as failed.

The upstream developers have made some unusual choices (static library only, installation in a private directory) but this will likely change with the switch to an automake and autoconf-based build system. I have reported the oddities that I found and I requested them to provide a pkg-config file to make it easier to compile and link unit tests exploiting CppUTest. I already used CppUTest to develop a small application running on an embedded Linux. At some point, I might try to use CppUTest for dpkg development. I believe that it makes for a good fit. dpkg is already C++ ready since dselect is written in C++ and reuses a good part of dpkg s code. In any case, if you like Test Driven Development and are writing C or C++ based applications, I invite you to try CppUTest.

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24 June 2012

Paul Tagliamonte: So, it happened

I m now a Debian Developer (or rather, I ve gotten my account created) I still don t feel right calling myself a Debian Developer just yet :) Before I go off with my usual rants, I think now s about a good of time as any to thank everyone who helped me here. So, thank you. Really. All of you. I only hope to live up to the stellar example of those before me.

Russell Coker: Targeted Advertising

Don Marti has written another blog post about targeted advertising [1]. His main point is that when a company uses the most targeted adverts (such as Google advertising) everyone knows that they are paying a small number of cents per click and nothing for the people who don t click. This compares to TV adverts which cost a lot of money and for which most viewers either leave the room or use fast-forward. Therefore using Google adverts doesn t send a signal about the amount of money invested in the products. Don also cited an example of a company sponsoring an OK Go film clip, that was a great idea, it shows that the company can do expensive things which are also a bit creative and fans will thank them (watch all the OK Go videos on Youtube, they are great). The next question is how else companies can advertise? One thing I d really like to see is sponsorship of authors. Pick an author and pay them a salary with paid editorial services for releasing a book a year for free in HTML and ebook formats. Having a fixed salary is a significant benefit when it comes time to apply for a mortgage or plan a holiday and being able to freely distribute books would be a significant benefit for an author who hasn t got a large fan base. In the computer industry it seems that there s a lot of potential for sponsoring people who produce free things. That ranges from free software and designs for free hardware to blog posts and documentation. Five years ago Sun had a blogging contest and my friend Dave Hall won a server that was worth $21K [2]. It would be nice if some other companies started doing similar things and if Sun did a repeat so some other people I like could get some free kit.

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21 June 2012

Russell Coker: New SE Linux Policy for Wheezy

I ve just uploaded a new SE Linux policy for Debian/Wheezy. It now works correctly with systemd and Chromium, two significant features that I wanted for Wheezy. Now it turns out that we have until the end of the month for Wheezy updates, so I may get another version of the policy uploaded before then. If so it will only be for relatively minor changes, I think that most SE Linux users would be reasonably happy with policy the way it is. Anything that doesn t work now can probably be solved by local configuration changes. execmem The current version of KDE in Debian is 4.8.4, it seems that large parts of the KDE environment depend on execmem access, this includes kwin and plasma-desktop. Basically there is no possibility of having a KDE desktop environment without those programs and therefore KDE depends on execmem access. Debugging this is difficult as the important programs SEGV when denied execmem access and the KDE crash handler really gets in the way of debugging it running /usr/bin/plasma-desktop results in the process forking a child and detaching from the gdb session. The most clear example of an execmem issue in KDE is from the program /usr/lib/kde4/libexec/kwin_opengl_test which gives the following error:
LLVM ERROR: Allocation failed when allocating new memory in the JIT
Can t allocate RWX Memory: Permission denied To make this work you run the command setsebool -P allow_execmem 1 which gives many domains the ability to create writable-executable memory regions. I raised this issue for discussion on the SE Linux mailing list and Hinnerk van Bruinehsen wrote an informative message in response summarising the situation [1]. It seems that it s possible to compile some of the programs in question to not use the JIT and therefore not require such access and there is a build option in Gentoo to allow it. But it s impractically difficult for me to fork KDE in Debian so the only option is to recommend that people enable the allow_execmem boolean for Debian desktop systems running SE Linux.

[1] http://marc.info/?l=selinux&m=134011618909818&w=2

/run and SE Linux Policy Currently Debian/Unstable is going through a transition to using /run...
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19 June 2012

Raphael Geissert: Deferring the execution of a command

More than once, I have found myself running a program that calls a given script multiple times, and sometimes, way too many times. In some cases, for instance, it was only necessary to run the script once in one minute, instead of hundreds of times.
Sounds like I want something like dpkg's deferred triggers, right? pretty much so.

With this need, deferred-run was born. Example:

$ deferred-run -l lock -- echo hello world
$ deferred-run -l lock -- echo hello world
$ sleep 3
$ deferred-run -l lock -- echo hello world
[some seconds later...]
hello world

In spite of multiple calls, echo was only called once.
Best part, it only requires sh and flock.

If you are interested in shell trickery, you should take a look at its code.

Steve Kemp: Writing a status panel the modern way

So status displays are cool. Seeing what is happening in real time is cool. As a proof of concept I put together a trivial load-graph:

http://static.steve.org.uk/load/

This is broken down into three parts:

Load Client: The load client is a trivial script which reads /proc/loadavg, and sends the 1-minute entry to a remote server, via a single UDP packet.
Load Server: The load-server is a service which listens for UDP traffic, and when it receives a new integer records that in a redis data-store.
Load Display: This is a HTML page which has the values from the store in it, which is then plotted using javscript.

So the UDP-server which receives load will receive two things:

load:N - The load figure. The text "load:" is literal, and present in case I decide to extend the stats..
x.x.x.x - The IP address from which it received the message.

This is inserted into a Redis database as an array. This array could then be fetched via an AJAX script to update the HTML display in real-time, but at the moment I just have a shell script which updates it in near-real time. The idea of having a UDP-server receive values from remote clients is interesting. We just need to define a mapping to redis. For me I've just done this:

receive a UDP packet with value "load:1.2" from source 1.2.3.4
append "1.2" to key "1.2.3.4-load".
append the value "1.2.3.4" to the global "known_hosts"

The values received can be truncated (i.e. keep only the most recent 60 entries) with ease, due to the available Redis primitives, and we can easily graph these using the qjplot library. Adding more metrics just means updating the clients to send "memfree:400m", "disk-free:50%", "users:2", "uptime:12345s", or similar. The storage is wonderfully abstract - all you need to do is get the graph-drawing code to a) Know which source to display, and b) which metric. For example, if we did extend the client to send that data I could draw a graph of the memory on host foo.example.com just by selecting "memfree" against the origin "1.2.3.4". ObQuote: "Come here, damn you, I want to touch you. " - Hellraiser

Jo Shields: Enormity

(This blog post is a more firm version of a series of tweets and forum posts I made a few weeks ago. This should also be considered a refresh of this post by Mirco Bauer a few years ago) It has been said that Mono is bloated, and that people should use lighter frameworks that don t pull in hundreds of meg . How much basis in reality is there for those comments? Well, let s do a little thought exercise. How much space is the minimum space needed for several languages to work? For this experiment, we will be looking at the required installation size on disk of several language frameworks, each time installing the bare minimum for a command-line hello world app in that language to run. For example, the Ruby result is the minimum install required to run:

puts 'Hello world'

and the Mono result is the minimum install required to run the following code, which has been compiled on a different machine using dmcs :

public class Hello1
 
   public static void Main()
    
      System.Console.WriteLine("Hello, World!");

Obviously, for dynamic languages like Ruby and Python, there is no compiler step needed. For languages like C# and Java, it is fair to compile these on a different machine as end-users of packages running these frameworks receive binaries, not source they do not need a development environment. So, on to the test environment. This is a bare bootstrapped AMD64 Debian Unstable system, as of today (i.e. debootstrap sid /tmp/badger ). Its install size is 275MB. So how much space? Ruby 1.9 Test code is as follows:

puts 'Hello world'