Search Results: "xam"

30 June 2020

Norbert Preining: TeX Live Debian update 20200629

More than a month has passed since the last update of TeX Live packages in Debian, so here is a new checkout!

All arch all packages have been updated to the tlnet state as of 2020-06-29, see the detailed update list below. Enjoy. New packages akshar, beamertheme-pure-minimalistic, biblatex-unified, biblatex-vancouver, bookshelf, commutative-diagrams, conditext, courierten, ektype-tanka, hvarabic, kpfonts-otf, marathi, menucard, namedef, pgf-pie, pwebmac, qrbill, semantex, shtthesis, tikz-lake-fig, tile-graphic, utf8add. Updated packages abnt, achemso, algolrevived, amiri, amscls, animate, antanilipsum, apa7, babel, bangtex, baskervillef, beamerappendixnote, beamerswitch, beamertheme-focus, bengali, bib2gls, biblatex-apa, biblatex-philosophy, biblatex-phys, biblatex-software, biblatex-swiss-legal, bibleref, bookshelf, bxjscls, caption, ccool, cellprops, changes, chemfig, circuitikz, cloze, cnltx, cochineal, commutative-diagrams, comprehensive, context, context-vim, cquthesis, crop, crossword, ctex, cweb, denisbdoc, dijkstra, doclicense, domitian, dps, draftwatermark, dvipdfmx, ebong, ellipsis, emoji, endofproofwd, eqexam, erewhon, erewhon-math, erw-l3, etbb, euflag, examplep, fancyvrb, fbb, fbox, fei, fira, fontools, fontsetup, fontsize, forest-quickstart, gbt7714, genealogytree, haranoaji, haranoaji-extra, hitszthesis, hvarabic, hyperxmp, icon-appr, kpfonts, kpfonts-otf, l3backend, l3build, l3experimental, l3kernel, latex-amsmath-dev, latexbangla, latex-base-dev, latexdemo, latexdiff, latex-graphics-dev, latexindent, latex-make, latexmp, latex-mr, latex-tools-dev, libertinus-fonts, libertinust1math, lion-msc, listings, logix, lshort-czech, lshort-german, lshort-polish, lshort-portuguese, lshort-russian, lshort-slovenian, lshort-thai, lshort-ukr, lshort-vietnamese, luamesh, lua-uca, luavlna, lwarp, marathi, memoir, mnras, moderntimeline, na-position, newcomputermodern, newpx, nicematrix, nodetree, ocgx2, oldstandard, optex, parskip, pdfcrop, pdfpc, pdftexcmds, pdfxup, pgf, pgfornament, pgf-pie, pgf-umlcd, pgf-umlsd, pict2e, plautopatch, poemscol, pst-circ, pst-eucl, pst-func, pstricks, pwebmac, pxjahyper, quran, rec-thy, reledmac, rest-api, sanskrit, sanskrit-t1, scholax, semantex, showexpl, shtthesis, suftesi, svg, tcolorbox, tex4ht, texinfo, thesis-ekf, thuthesis, tkz-doc, tlshell, toptesi, tuda-ci, tudscr, twemoji-colr, univie-ling, updmap-map, vancouver, velthuis, witharrows, wtref, xecjk, xepersian-hm, xetex-itrans, xfakebold, xindex, xindy, xltabular, yathesis, ydoc, yquant, zref.

26 June 2020

Dirk Eddelbuettel: littler 0.3.11: docopt updates

The twelveth release of littler as a CRAN package is now available, following in the fourteen-ish year history as a package started by Jeff in 2006, and joined by me a few weeks later. littler is the first command-line interface for R as it predates Rscript. It allows for piping as well for shebang scripting via #!, uses command-line arguments more consistently and still starts faster. It also always loaded the methods package which Rscript only started to do in recent years. littler lives on Linux and Unix, has its difficulties on macOS due to yet-another-braindeadedness there (who ever thought case-insensitive filesystems as a default where a good idea?) and simply does not exist on Windows (yet the build system could be extended see RInside for an existence proof, and volunteers are welcome!). See the FAQ vignette on how to add it to your PATH. A few examples are highlighted at the Github repo, as well as in the examples vignette. This release mostly responds to the recent docopt release 0.7.0 which brought a breaking change for quoted arguments. In short, it is for the better because an option --as-cran is now available parsed as opt$as_cran which is easier than the earlier form where we needed to back-tick protect as-cran containing an underscore. We also added a new portmanteau-ish option to roxy.r. The NEWS file entry is below.

Changes in littler version 0.3.11 (2020-06-26)

Changes in examples

Scripts check.r and rcc.r updated to reflect updated docopt 0.7.0 behaviour of quoted arguments

The roxy.r script has a new ease-of-use option -f --full regrouping two other options.

CRANberries provides a comparison to the previous release. Full details for the littler release are provided as usual at the ChangeLog page. The code is available via the GitHub repo, from tarballs and now of course also from its CRAN page and via install.packages("littler"). Binary packages are available directly in Debian as well as soon via Ubuntu binaries at CRAN thanks to the tireless Michael Rutter. Comments and suggestions are welcome at the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Chris Lamb: On the pleasure of hating

People love to tell you that they "don't watch sports" but the story of Lance Armstrong provides a fascinating lens through which to observe our culture at large. For example, even granting all that he did and all the context in which he did it, why do sports cheats act like a lightning rod for such an instinctive hatred? After all, the sheer level of distaste directed at people such as Lance eludes countless other criminals in our society, many of whom have taken a lot more with far fewer scruples. The question is not one of logic or rationality, but of proportionality. In some ways it should be unsurprising. In all areas of life, we instinctively prefer binary judgements to moral ambiguities and the sports cheat is a clich of moral bankruptcy cheating at something so seemingly trivial as a sport actually makes it more, not less, offensive to us. But we then find ourselves strangely enthralled by them, drawn together in admiration of their outlaw-like tenacity, placing them strangely close to criminal folk heroes. Clearly, sport is not as unimportant as we like to claim it is. In Lance's case in particular though, there is undeniably a Shakespearean quality to the story and we are forced to let go of our strict ideas of right and wrong and appreciate all the nuance.

There is a lot of this nuance in Marina Zenovich's new documentary. In fact, there's a lot of everything. At just under four hours, ESPN's Lance combines the duration of a Tour de France stage with the depth of the peloton an endurance event compared to the bite-sized hagiography of Michael Jordan's The Last Dance. Even for those who follow Armstrong's story like a mini-sport in itself, Lance reveals new sides to this man for all seasons. For me, not only was this captured in his clumsy approximations at being a father figure but also in him being asked something I had not read in countless tell-all books: did his earlier experiments in drug-taking contribute to his cancer? But even in 2020 there are questions that remain unanswered. By needlessly returning to the sport in 2009, did Lance subconsciously want to get caught? Why does he not admit he confessed to Betsy Andreu back in 1999 but will happily apologise to her today for slurring her publicly on this very point? And why does he remain so vindictive towards former-teammate Floyd Landis? In all of Armstrong's evasions and masterful control of the narrative, there is the gnawing feeling that we don't even know what questions we should be even asking. As ever, the questions are more interesting than the answers.

Lance also reminded me of how professional cycling's obsession with national identity. Although I was intuitively aware of it to some degree, I had not fully grasped how much this kind of stereotyping runs through the veins of the sport itself, just like the drugs themselves. Journalist Daniel Friebe first offers us the portrait of:

Spaniards tend to be modest, very humble. Very unpretentious. And the Italians are loud, vain and outrageous showmen.

Former directeur sportif Johan Bruyneel then asserts that "Belgians are hard workers... they are ambitious to a certain point, but not overly ambitious", and cyclist J rg Jaksche concludes with:

The Germans are very organised and very structured. And then the French, now I have to be very careful because I am German, but the French are slightly superior.

This kind of lazy caricature is nothing new, especially for those brought up on a solid diet of Tintin and Asterix, but although all these examples are seemingly harmless, why does the underlying idea of ascribing moral, social or political significance to genetic lineage remain so durable in today's age of anti-racism? To be sure, culture is not quite the same thing as race, but being judged by the character of one's ancestors rather than the actions of an individual is, at its core, one of the many conflations at the heart of racism. There is certainly a large amount of cognitive dissonance at work, especially when Friebe elaborates:

East German athletes were like incredible robotic figures, fallen off a production line somewhere behind the Iron Curtain...

... but then bermensch Jan Ullrich is immediately described as "emotional" and "struggled to live the life of a professional cyclist 365 days a year". We see the habit to stereotype is so ingrained that even in the face of this obvious contradiction, Friebe unironically excuses Ullrich's failure to live up his German roots due to him actually being "Mediterranean".

I mention all this as I am known within my circles for remarking on these national characters, even collecting stereotypical examples of Italians 'being Italian' and the French 'being French' at times. Contrary to evidence, I don't believe in this kind of innate quality but what I do suspect is that people generally behave how they think they ought to behave, perhaps out of sheer imitation or the simple pleasure of conformity. As the novelist Will Self put it:

It's quite a complicated collective imposture, people pretending to be British and people pretending to be French, and then they get really angry with each other over what they're pretending to be.

The really remarkable thing about this tendency is that even if we consciously notice it there is no seemingly no escape even I could not smirk when I considered that a brash Texan winning the Tour de France actually combines two of America's cherished obsessions: winning... and annoying the French.

25 June 2020

Russell Coker: How Will the Pandemic Change Things?

The Bulwark has an interesting article on why they can t Reopen America [1]. I wonder how many changes will be long term. According to the Wikipedia List of Epidemics [2] Covid-19 so far hasn t had a high death toll when compared to other pandemics of the last 100 years. People s reactions to this vary from doing nothing to significant isolation, the question is what changes in attitudes will be significant enough to change society. Transport One thing that has been happening recently is a transition in transport. It s obvious that we need to reduce CO2 and while electric cars will address the transport part of the problem in the long term changing to electric public transport is the cheaper and faster way to do it in the short term. Before Covid-19 the peak hour public transport in my city was ridiculously overcrowded, having people unable to board trams due to overcrowding was really common. If the economy returns to it s previous state then I predict less people on public transport, more traffic jams, and many more cars idling and polluting the atmosphere. Can we have mass public transport that doesn t give a significant disease risk? Maybe if we had significantly more trains and trams and better ventilation with more airflow designed to suck contaminated air out. But that would require significant engineering work to design new trams, trains, and buses as well as expense in refitting or replacing old ones. Uber and similar companies have been taking over from taxi companies, one major feature of those companies is that the vehicles are not dedicated as taxis. Dedicated taxis could easily be designed to reduce the spread of disease, the famed Black Cab AKA Hackney Carriage [3] design in the UK has a separate compartment for passengers with little air flow to/from the driver compartment. It would be easy to design such taxis to have entirely separate airflow and if setup to only take EFTPOS and credit card payment could avoid all contact between the driver and passengers. I would prefer to have a Hackney Carriage design of vehicle instead of a regular taxi or Uber. Autonomous cars have been shown to basically work. There are some concerns about safety issues as there are currently corner cases that car computers don t handle as well as people, but of course there are also things computers do better than people. Having an autonomous taxi would be a benefit for anyone who wants to avoid other people. Maybe approval could be rushed through for autonomous cars that are limited to 40Km/h (the maximum collision speed at which a pedestrian is unlikely to die), in central city areas and inner suburbs you aren t likely to drive much faster than that anyway. Car share services have been becoming popular, for many people they are significantly cheaper than owning a car due to the costs of regular maintenance, insurance, and depreciation. As the full costs of car ownership aren t obvious people may focus on the disease risk and keep buying cars. Passenger jets are ridiculously cheap. But this relies on the airline companies being able to consistently fill the planes. If they were to add measures to reduce cross contamination between passengers which slightly reduces the capacity of planes then they need to increase ticket prices accordingly which then reduces demand. If passengers are just scared of flying in close proximity and they can t fill planes then they will have to increase prices which again reduces demand and could lead to a death spiral. If in the long term there aren t enough passengers to sustain the current number of planes in service then airline companies will have significant financial problems, planes are expensive assets that are expected to last for a long time, if they can t use them all and can t sell them then airline companies will go bankrupt. It s not reasonable to expect that the same number of people will be travelling internationally for years (if ever). Due to relying on economies of scale to provide low prices I don t think it s possible to keep prices the same no matter what they do. A new economic balance of flights costing 2-3 times more than we are used to while having significantly less passengers seems likely. Governments need to spend significant amounts of money to improve trains to take over from flights that are cancelled or too expensive. Entertainment The article on The Bulwark mentions Las Vegas as a city that will be hurt a lot by reductions in travel and crowds, the same thing will happen to tourist regions all around the world. Australia has a significant tourist industry that will be hurt a lot. But the mention of Las Vegas makes me wonder what will happen to the gambling in general. Will people avoid casinos and play poker with friends and relatives at home? It seems that small stakes poker games among friends will be much less socially damaging than casinos, will this be good for society? The article also mentions cinemas which have been on the way out since the video rental stores all closed down. There s lots of prime real estate used for cinemas and little potential for them to make enough money to cover the rent. Should we just assume that most uses of cinemas will be replaced by Netflix and other streaming services? What about teenage dates, will kissing in the back rows of cinemas be replaced by Netflix and chill ? What will happen to all the prime real estate used by cinemas? Professional sporting matches have been played for a TV-only audience during the pandemic. There s no reason that they couldn t make a return to live stadium audiences when there is a vaccine for the disease or the disease has been extinguished by social distancing. But I wonder if some fans will start to appreciate the merits of small groups watching large TVs and not want to go back to stadiums, can this change the typical behaviour of groups? Restaurants and cafes are going to do really badly. I previously wrote about my experience running an Internet Cafe and why reopening businesses soon is a bad idea [4]. The question is how long this will go for and whether social norms about personal space will change things. If in the long term people expect 25% more space in a cafe or restaurant that s enough to make a significant impact on profitability for many small businesses. When I was young the standard thing was for people to have dinner at friends homes. Meeting friends for dinner at a restaurant was uncommon. Recently it seemed to be the most common practice for people to meet friends at a restaurant. There are real benefits to meeting at a restaurant in terms of effort and location. Maybe meeting friends at their home for a delivered dinner will become a common compromise, avoiding the effort of cooking while avoiding the extra expense and disease risk of eating out. Food delivery services will do well in the long term, it s one of the few industry segments which might do better after the pandemic than before. Work Many companies are discovering the benefits of teleworking, getting it going effectively has required investing in faster Internet connections and hardware for employees. When we have a vaccine the equipment needed for teleworking will still be there and we will have a discussion about whether it should be used on a more routine basis. When employees spend more than 2 hours per day travelling to and from work (which is very common for people who work in major cities) that will obviously limit the amount of time per day that they can spend working. For the more enthusiastic permanent employees there seems to be a benefit to the employer to allow working from home. It s obvious that some portion of the companies that were forced to try teleworking will find it effective enough to continue in some degree. One company that I work for has quit their coworking space in part because they were concerned that the coworking company might go bankrupt due to the pandemic. They seem to have become a 100% work from home company for the office part of the work (only on site installation and stock management is done at corporate locations). Companies running coworking spaces and other shared offices will suffer first as their clients have short term leases. But all companies renting out office space in major cities will suffer due to teleworking. I wonder how this will affect the companies providing services to the office workers, the cafes and restaurants etc. Will there end up being so much unused space in central city areas that it s not worth converting the city cinemas into useful space? There s been a lot of news about Zoom and similar technologies. Lots of other companies are trying to get into that business. One thing that isn t getting much notice is remote access technologies for desktop support. If the IT people can t visit your desk because you are working from home then they need to be able to remotely access it to fix things. When people make working from home a large part of their work time the issue of who owns peripherals and how they are tracked will get interesting. In a previous blog post I suggested that keyboards and mice not be treated as assets [5]. But what about monitors, 4G/Wifi access points, etc? Some people have suggested that there will be business sectors benefiting from the pandemic, such as telecoms and e-commerce. If you have a bunch of people forced to stay home who aren t broke (IE a large portion of the middle class in Australia) they will probably order delivery of stuff for entertainment. But in the long term e-commerce seems unlikely to change much, people will spend less due to economic uncertainty so while they may shift some purchasing to e-commerce apart from home delivery of groceries e-commerce probably won t go up overall. Generally telecoms won t gain anything from teleworking, the Internet access you need for good Netflix viewing is generally greater than that needed for good video-conferencing. Money I previously wrote about a Basic Income for Australia [6]. One of the most cited reasons for a Basic Income is to deal with robots replacing people. Now we are at the start of what could be a long term economic contraction caused by the pandemic which could reduce the scale of the economy by a similar degree while also improving the economic case for a robotic workforce. We should implement a Universal Basic Income now. I previously wrote about the make-work jobs and how we could optimise society to achieve the worthwhile things with less work [7]. My ideas about optimising public transport and using more car share services may not work so well after the pandemic, but the rest should work well. Business There are a number of big companies that are not aiming for profitability in the short term. WeWork and Uber are well documented examples. Some of those companies will hopefully go bankrupt and make room for more responsible companies. The co-working thing was always a precarious business. The companies renting out office space usually did so on a monthly basis as flexibility was one of their selling points, but they presumably rented buildings on an annual basis. As the profit margins weren t particularly high having to pay rent on mostly empty buildings for a few months will hurt them badly. The long term trend in co-working spaces might be some sort of collaborative arrangement between the people who run them and the landlords similar to the way some of the hotel chains have profit sharing agreements with land owners to avoid both the capital outlay for buying land and the risk involved in renting. Also city hotels are very well equipped to run office space, they have the staff and the procedures for running such a business, most hotels also make significant profits from conventions and conferences. The way the economy has been working in first world countries has been about being as competitive as possible. Just in time delivery to avoid using storage space and machines to package things in exactly the way that customers need and no more machines than needed for regular capacity. This means that there s no spare capacity when things go wrong. A few years ago a company making bolts for the car industry went bankrupt because the car companies forced the prices down, then car manufacture stopped due to lack of bolts this could have been a wake up call but was ignored. Now we have had problems with toilet paper shortages due to it being packaged in wholesale quantities for offices and schools not retail quantities for home use. Food was destroyed because it was created for restaurant packaging and couldn t be packaged for home use in a reasonable amount of time. Farmer s markets alleviate some of the problems with packaging food etc. But they aren t a good option when there s a pandemic as disease risk makes them less appealing to customers and therefore less profitable for vendors. Religion Many religious groups have supported social distancing. Could this be the start of more decentralised religion? Maybe have people read the holy book of their religion and pray at home instead of being programmed at church? We can always hope.

24 June 2020

Ian Jackson: Renaming the primary git branch to "trunk"

I have been convinced by the arguments that it's not nice to keep using the word master for the default git branch. Regardless of the etymology (which is unclear), some people say they have negative associations for this word, Changing this upstream in git is complicated on a technical level and, sadly, contested. But git is flexible enough that I can make this change in my own repositories. Doing so is not even so difficult. So: Announcement I intend to rename master to trunk in all repositories owned by my personal hat. To avoid making things very complicated for myself I will just delete refs/heads/master when I make this change. So there may be a little disruption to downstreams. I intend make this change everywhere eventually. But rather than front-loading the effort, I'm going to do this to repositories as I come across them anyway. That will allow me to update all the docs references, any automation, etc., at a point when I have those things in mind anyway. Also, doing it this way will allow me to focus my effort on the most active projects, and avoids me committing to a sudden large pile of fiddly clerical work. But: if you have an interest in any repository in particular that you want updated, please let me know so I can prioritise it. Bikeshed Why "trunk"? "Main" has been suggested elswewhere, and it is often a good replacement for "master" (for example, we can talk very sensibly about a disk's Main Boot Record, MBR). But "main" isn't quite right for the VCS case; for example a "main" branch ought to have better quality than is typical for the primary development branch. Conversely, there is much precedent for "trunk". "Trunk" was used to refer to this concept by at least SVN, CVS, RCS and CSSC (and therefore probably SCCS) - at least in the documentation, although in some of these cases the command line API didn't have a name for it. So "trunk" it is. Aside: two other words - passlist, blocklist People are (finally!) starting to replace "blacklist" and "whitelist". Seriously, why has it taken everyone this long? I have been using "blocklist" and "passlist" for these concepts for some time. They are drop-in replacements. I have also heard "allowlist" and "denylist" suggested, but they are cumbersome and cacophonous. Also "allow" and "deny" seem to more strongly imply an access control function than merely "pass" and "block", and the usefulness of passlists and blocklists extends well beyond access control: protocol compatibility and ABI filtering are a couple of other use cases.

comments

22 June 2020

Evgeni Golov: mass-migrating modules inside an Ansible Collection

Im the Foreman project, we've been maintaining a collection of Ansible modules to manage Foreman installations since 2017. That is, 2 years before Ansible had the concept of collections at all. For that you had to set library (and later module_utils and doc_fragment_plugins) in ansible.cfg and effectively inject our modules, their helpers and documentation fragments into the main Ansible namespace. Not the cleanest solution, but it worked quiet well for us. When Ansible started introducing Collections, we quickly joined, as the idea of namespaced, easily distributable and usable content units was great and exactly matched what we had in mind. However, collections are only usable in Ansible 2.8, or actually 2.9 as 2.8 can consume them, but tooling around building and installing them is lacking. Because of that we've been keeping our modules usable outside of a collection. Until recently, when we decided it's time to move on, drop that compatibility (which costed a few headaches over the time) and release a shiny 1.0.0. One of the changes we wanted for 1.0.0 is renaming a few modules. Historically we had the module names prefixed with foreman_ and katello_, depending whether they were designed to work with Foreman (and plugins) or Katello (which is technically a Foreman plugin, but has a way more complicated deployment and currently can't be easily added to an existing Foreman setup). This made sense as long as we were injecting into the main Ansible namespace, but with collections the names be became theforemam.foreman.foreman_ <something> and while we all love Foreman, that was a bit too much. So we wanted to drop that prefix. And while at it, also change some other names (like ptable, which became partition_table) to be more readable. But how? There is no tooling that would rename all files accordingly, adjust examples and tests. Well, bash to the rescue! I'm usually not a big fan of bash scripts, but renaming files, searching and replacing strings? That perfectly fits! First of all we need a way map the old name to the new name. In most cases it's just "drop the prefix", for the others you can have some if/elif/fi:

prefixless_name=$(echo $ old_name   sed -E 's/^(foreman katello)_//')
if [[ $ old_name  == 'foreman_environment' ]]; then
  new_name='puppet_environment'
elif [[ $ old_name  == 'katello_sync' ]]; then
  new_name='repository_sync'
elif [[ $ old_name  == 'katello_upload' ]]; then
  new_name='content_upload'
elif [[ $ old_name  == 'foreman_ptable' ]]; then
  new_name='partition_table'
elif [[ $ old_name  == 'foreman_search_facts' ]]; then
  new_name='resource_info'
elif [[ $ old_name  == 'katello_manifest' ]]; then
  new_name='subscription_manifest'
elif [[ $ old_name  == 'foreman_model' ]]; then
  new_name='hardware_model'
else
  new_name=$ prefixless_name 
fi

That defined, we need to actually have a $ old_name . Well, that's a for loop over the modules, right?

for module in $ BASE /foreman_*py $ BASE /katello_*py; do
  old_name=$(basename $ module  .py)
   
done

While we're looping over files, let's rename them and all the files that are associated with the module:

# rename the module
git mv $ BASE /$ old_name .py $ BASE /$ new_name .py
# rename the tests and test fixtures
git mv $ TESTS /$ old_name .yml $ TESTS /$ new_name .yml
git mv tests/fixtures/apidoc/$ old_name .json tests/fixtures/apidoc/$ new_name .json
for testfile in $ TESTS /fixtures/$ old_name -*.yml; do
  git mv $ testfile  $(echo $ testfile   sed "s/$ old_name /$ new_name /")
done

Now comes the really tricky part: search and replace. Let's see where we need to replace first:

in the module file
1. module key of the DOCUMENTATION stanza (e.g. module: foreman_example)
2. all examples (e.g. foreman_example: )
in all test playbooks (e.g. foreman_example: )
in pytest's conftest.py and other files related to test execution
in documentation

sed -E -i "/^(\s+$ old_name  module):/ s/$ old_name /$ new_name /g" $ BASE /*.py
sed -E -i "/^(\s+$ old_name  module):/ s/$ old_name /$ new_name /g" tests/test_playbooks/tasks/*.yml tests/test_playbooks/*.yml
sed -E -i "/'$ old_name '/ s/$ old_name /$ new_name /" tests/conftest.py tests/test_crud.py
sed -E -i "/ $ old_name  / s/$ old_name /$ new_name /g' README.md docs/*.md

You've probably noticed I used $ BASE and $ TESTS and never defined them Lazy me. But here is the full script, defining the variables and looping over all the modules.

#!/bin/bash
BASE=plugins/modules
TESTS=tests/test_playbooks
RUNTIME=meta/runtime.yml
echo "plugin_routing:" > $ RUNTIME 
echo "  modules:" >> $ RUNTIME 
for module in $ BASE /foreman_*py $ BASE /katello_*py; do
  old_name=$(basename $ module  .py)
  prefixless_name=$(echo $ old_name   sed -E 's/^(foreman katello)_//')
  if [[ $ old_name  == 'foreman_environment' ]]; then
    new_name='puppet_environment'
  elif [[ $ old_name  == 'katello_sync' ]]; then
    new_name='repository_sync'
  elif [[ $ old_name  == 'katello_upload' ]]; then
    new_name='content_upload'
  elif [[ $ old_name  == 'foreman_ptable' ]]; then
    new_name='partition_table'
  elif [[ $ old_name  == 'foreman_search_facts' ]]; then
    new_name='resource_info'
  elif [[ $ old_name  == 'katello_manifest' ]]; then
    new_name='subscription_manifest'
  elif [[ $ old_name  == 'foreman_model' ]]; then
    new_name='hardware_model'
  else
    new_name=$ prefixless_name 
  fi
  echo "renaming $ old_name  to $ new_name "
  git mv $ BASE /$ old_name .py $ BASE /$ new_name .py
  git mv $ TESTS /$ old_name .yml $ TESTS /$ new_name .yml
  git mv tests/fixtures/apidoc/$ old_name .json tests/fixtures/apidoc/$ new_name .json
  for testfile in $ TESTS /fixtures/$ old_name -*.yml; do
    git mv $ testfile  $(echo $ testfile   sed "s/$ old_name /$ new_name /")
  done
  sed -E -i "/^(\s+$ old_name  module):/ s/$ old_name /$ new_name /g" $ BASE /*.py
  sed -E -i "/^(\s+$ old_name  module):/ s/$ old_name /$ new_name /g" tests/test_playbooks/tasks/*.yml tests/test_playbooks/*.yml
  sed -E -i "/'$ old_name '/ s/$ old_name /$ new_name /" tests/conftest.py tests/test_crud.py
  sed -E -i "/ $ old_name  / s/$ old_name /$ new_name /g' README.md docs/*.md
  echo "    $ old_name :" >> $ RUNTIME 
  echo "      redirect: $ new_name " >> $ RUNTIME 
  git commit -m "rename $ old_name  to $ new_name " $ BASE  tests/ README.md docs/ $ RUNTIME 
done

As a bonus, the script will also generate a meta/runtime.yml which can be used by Ansible 2.10+ to automatically use the new module names if the playbook contains the old ones. Oh, and yes, this is probably not the nicest script you'll read this year. Maybe not even today. But it got the job nicely done and I don't intend to need it again anyways.

21 June 2020

Dirk Eddelbuettel: RcppGSL 0.3.8: More fixes and polish

Release 0.3.8 of RcppGSL is now getting onto CRAN. The RcppGSL package provides an interface from R to the GNU GSL using the Rcpp package. Peter Carbonetto let us know in issue #25 that the included example now showed linker errors on (everybody s favourite CRAN platform) Slowlaris. Kidding aside, the added compiler variety really has benefits because we were indeed missing a good handful or two of inline statements in the headers which our good friends g++ and clang++ apparently let us get away with. This has been fixed, and a little bit of the usual package polish and cleanup has been added; see the list of detailed changes below.

Changes in version 0.3.8 (2020-06-21)

A few missing inline statements were added to the headers fixing a (genuine) error that was seen only on Solaris (Dirk).

The nice colNorm example is now in a file by itself, the previous versions are off in a new file colNorm_old.cpp (Dirk).

The README.me now sports two new badges (Dirk).

Travis CI was updated to 'bionic' and R 4.0 (Dirk).

Special thanks also to CRAN for a super-smooth and fully automated processing of a package with both compiled code and two handful of reverse dependencies. Courtesy of CRANberries, a summary of changes to the most recent release is also available. More information is on the RcppGSL page. Questions, comments etc should go to the issue tickets at the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

20 June 2020

Dima Kogan: OpenCV C API transition. A rant.

I just went through a debugging exercise that was so ridiculous, I just had to write it up. Some of this probably should go into a bug report instead of a rant, but I'm tired. And clearly I don't care anymore. OK, so I'm doing computer vision work. OpenCV has been providing basic functions in this area, so I have been using them for a while. Just for really, really basic stuff, like projection. The C API was kinda weird, and their error handling is a bit ridiculous (if you give it arguments it doesn't like, it asserts!), but it has been working fine for a while. At some point (around OpenCV 3.0) somebody over there decided that they didn't like their C API, and that this was now a C++ library. Except the docs still documented the C API, and the website said it supported C, and the code wasn't actually removed. They just kinda stopped testing it and thinking about it. So it would mostly continue to work, except some poor saps would see weird failures; like this and this, for instance. OpenCV 3.2 was the last version where it was mostly possible to keep using the old C code, even when compiling without optimizations. So I was doing that for years. So now, in 2020, Debian is finally shipping a version of OpenCV that definitively does not work with the old code, so I had to do something. Over time I stopped using everything about OpenCV, except a few cvProjectPoints2() calls. So I decided to just write a small C++ shim to call the new version of that function, expose that with =extern "C"= to the rest of my world, and I'd be done. And normally I would be, but this is OpenCV we're talking about. I wrote the shim, and it didn't work. The code built and ran, but the results were wrong. After some pointless debugging, I boiled the problem down to this test program:

#include <opencv2/calib3d.hpp>
#include <stdio.h>
int main(void)
 
    double fx = 1000.0;
    double fy = 1000.0;
    double cx = 1000.0;
    double cy = 1000.0;
    double _camera_matrix[] =
          fx,  0, cx,
          0,  fy, cy,
          0,   0,  1  ;
    cv::Mat camera_matrix(3,3, CV_64FC1, _camera_matrix);
    double pp[3] =  1., 2., 10. ;
    double qq[2] =  444, 555 ;
    int N=1;
    cv::Mat object_points(N,3, CV_64FC1, pp);
    cv::Mat image_points (N,2, CV_64FC1, qq);
    // rvec,tvec
    double _zero3[3] =  ;
    cv::Mat zero3(1,3,CV_64FC1, _zero3);
    cv::projectPoints( object_points,
                       zero3,zero3,
                       camera_matrix,
                       cv::noArray(),
                       image_points,
                       cv::noArray(), 0.0);
    fprintf(stderr, "manually-projected no-distortion: %f %f\n",
            pp[0]/pp[2] * fx + cx,
            pp[1]/pp[2] * fy + cy);
    fprintf(stderr, "opencv says: %f %f\n", qq[0], qq[1]);
    return 0;

This is as trivial as it gets. I project one point through a pinhole camera, and print out the right answer (that I can easily compute, since this is trivial), and what OpenCV reports:

$ g++ -I/usr/include/opencv4 -o tst tst.cc -lopencv_calib3d -lopencv_core && ./tst
manually-projected no-distortion: 1100.000000 1200.000000
opencv says: 444.000000 555.000000

Well that's no good. The answer is wrong, but it looks like it didn't even write anything into the output array. Since this is supposed to be a thin shim to C code, I want this thing to be filling in C arrays, which is what I'm doing here:

double qq[2] =  444, 555 ;
int N=1;
cv::Mat image_points (N,2, CV_64FC1, qq);

This is how the C API has worked forever, and their C++ API works the same way, I thought. Nothing barfed, not at build time, or run time. Fine. So I went to figure this out. In the true spirit of C++, the new API is inscrutable. I'm passing in cv::Mat, but the API wants cv::InputArray for some arguments and cv::OutputArray for others. Clearly cv::Mat can be coerced into either of those types (and that's what you're supposed to do), but the details are not meant to be understood. You can read the snazzy C++-style documentation. Clicking on "OutputArray" in the doxygen gets you here. Then I guess you're supposed to click on "_OutputArray", and you get here. Understand what's going on now? Me neither. Stepping through the code revealed the problem. cv::projectPoints() looks like this:

void cv::projectPoints( InputArray _opoints,
                        InputArray _rvec,
                        InputArray _tvec,
                        InputArray _cameraMatrix,
                        InputArray _distCoeffs,
                        OutputArray _ipoints,
                        OutputArray _jacobian,
                        double aspectRatio )
 
    ....
    _ipoints.create(npoints, 1, CV_MAKETYPE(depth, 2), -1, true);
    ....

I.e. they're allocating a new data buffer for the output, and giving it back to me via the OutputArray object. This object already had a buffer, and that's where I was expecting the output to go. Instead it went to the brand-new buffer I didn't want. Issues:

The OutputArray object knows it already has a buffer, and they could just use it instead of allocating a new one
If for some reason my buffer smells bad, they could complain to tell me they're ignoring it to save me the trouble of debugging, and then bitching about it on the internet
I think dynamic memory allocation smells bad
Doing it this way means the new function isn't a drop-in replacement for the old function

Well that's just super. I can call the C++ function, copy the data into the place it's supposed to go to, and then deallocate the extra buffer. Or I can pull out the meat of the function I want into my project, and then I can drop the OpenCV dependency entirely. Clearly that's the way to go. So I go poking back into their code to grab what I need, and here's what I see:

static void cvProjectPoints2Internal( const CvMat* objectPoints,
                  const CvMat* r_vec,
                  const CvMat* t_vec,
                  const CvMat* A,
                  const CvMat* distCoeffs,
                  CvMat* imagePoints, CvMat* dpdr CV_DEFAULT(NULL),
                  CvMat* dpdt CV_DEFAULT(NULL), CvMat* dpdf CV_DEFAULT(NULL),
                  CvMat* dpdc CV_DEFAULT(NULL), CvMat* dpdk CV_DEFAULT(NULL),
                  CvMat* dpdo CV_DEFAULT(NULL),
                  double aspectRatio CV_DEFAULT(0) )
 
...

Looks familiar? It should. Because this is the original C-API function they replaced. So in their quest to move to C++, they left the original code intact, C API and everything, un-exposed it so you couldn't call it anymore, and made a new, shitty C++ wrapper for people to call instead. CvMat is still there. I have no words. Yes, this is a massive library, and maybe other parts of it indeed did make some sort of non-token transition, but this thing is ridiculous. In the end, here's the function I ended up with (licensed as OpenCV; see the comment)

// The implementation of project_opencv is based on opencv. The sources have
// been heavily modified, but the opencv logic remains. This function is a
// cut-down cvProjectPoints2Internal() to keep only the functionality I want and
// to use my interfaces. Putting this here allows me to drop the C dependency on
// opencv. Which is a good thing, since opencv dropped their C API
//
// from opencv-4.2.0+dfsg/modules/calib3d/src/calibration.cpp
//
// Copyright (C) 2000-2008, Intel Corporation, all rights reserved.
// Copyright (C) 2009, Willow Garage Inc., all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
//   * Redistribution's of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//
//   * Redistribution's in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//
//   * The name of the copyright holders may not be used to endorse or promote products
//     derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors "as is" and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the Intel Corporation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
typedef union
 
    struct
     
        double x,y;
     ;
    double xy[2];
  point2_t;
typedef union
 
    struct
     
        double x,y,z;
     ;
    double xyz[3];
  point3_t;
void project_opencv( // outputs
                     point2_t* q,
                     point3_t* dq_dp,               // may be NULL
                     double* dq_dintrinsics_nocore, // may be NULL
                     // inputs
                     const point3_t* p,
                     int N,
                     const double* intrinsics,
                     int Nintrinsics)
 
    const double fx = intrinsics[0];
    const double fy = intrinsics[1];
    const double cx = intrinsics[2];
    const double cy = intrinsics[3];
    double k[12] =  ;
    for(int i=0; i<Nintrinsics-4; i++)
        k[i] = intrinsics[i+4];
    for( int i = 0; i < N; i++ )
     
        double z_recip = 1./p[i].z;
        double x = p[i].x * z_recip;
        double y = p[i].y * z_recip;
        double r2      = x*x + y*y;
        double r4      = r2*r2;
        double r6      = r4*r2;
        double a1      = 2*x*y;
        double a2      = r2 + 2*x*x;
        double a3      = r2 + 2*y*y;
        double cdist   = 1 + k[0]*r2 + k[1]*r4 + k[4]*r6;
        double icdist2 = 1./(1 + k[5]*r2 + k[6]*r4 + k[7]*r6);
        double xd      = x*cdist*icdist2 + k[2]*a1 + k[3]*a2 + k[8]*r2+k[9]*r4;
        double yd      = y*cdist*icdist2 + k[2]*a3 + k[3]*a1 + k[10]*r2+k[11]*r4;
        q[i].x = xd*fx + cx;
        q[i].y = yd*fy + cy;
        if( dq_dp )
         
            double dx_dp[] =   z_recip, 0,       -x*z_recip  ;
            double dy_dp[] =   0,       z_recip, -y*z_recip  ;
            for( int j = 0; j < 3; j++ )
             
                double dr2_dp = 2*x*dx_dp[j] + 2*y*dy_dp[j];
                double dcdist_dp = k[0]*dr2_dp + 2*k[1]*r2*dr2_dp + 3*k[4]*r4*dr2_dp;
                double dicdist2_dp = -icdist2*icdist2*(k[5]*dr2_dp + 2*k[6]*r2*dr2_dp + 3*k[7]*r4*dr2_dp);
                double da1_dp = 2*(x*dy_dp[j] + y*dx_dp[j]);
                double dmx_dp = (dx_dp[j]*cdist*icdist2 + x*dcdist_dp*icdist2 + x*cdist*dicdist2_dp +
                                k[2]*da1_dp + k[3]*(dr2_dp + 4*x*dx_dp[j]) + k[8]*dr2_dp + 2*r2*k[9]*dr2_dp);
                double dmy_dp = (dy_dp[j]*cdist*icdist2 + y*dcdist_dp*icdist2 + y*cdist*dicdist2_dp +
                                k[2]*(dr2_dp + 4*y*dy_dp[j]) + k[3]*da1_dp + k[10]*dr2_dp + 2*r2*k[11]*dr2_dp);
                dq_dp[i*2 + 0].xyz[j] = fx*dmx_dp;
                dq_dp[i*2 + 1].xyz[j] = fy*dmy_dp;
             
         
        if( dq_dintrinsics_nocore )
         
            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 0] = fx*x*icdist2*r2;
            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 0] = fy*(y*icdist2*r2);
            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 1] = fx*x*icdist2*r4;
            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 1] = fy*y*icdist2*r4;
            if( Nintrinsics-4 > 2 )
             
                dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 2] = fx*a1;
                dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 2] = fy*a3;
                dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 3] = fx*a2;
                dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 3] = fy*a1;
                if( Nintrinsics-4 > 4 )
                 
                    dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 4] = fx*x*icdist2*r6;
                    dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 4] = fy*y*icdist2*r6;
                    if( Nintrinsics-4 > 5 )
                     
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 5] = fx*x*cdist*(-icdist2)*icdist2*r2;
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 5] = fy*y*cdist*(-icdist2)*icdist2*r2;
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 6] = fx*x*cdist*(-icdist2)*icdist2*r4;
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 6] = fy*y*cdist*(-icdist2)*icdist2*r4;
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 7] = fx*x*cdist*(-icdist2)*icdist2*r6;
                        dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 7] = fy*y*cdist*(-icdist2)*icdist2*r6;
                        if( Nintrinsics-4 > 8 )
                         
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 8] = fx*r2; //s1
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 8] = fy*0; //s1
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 9] = fx*r4; //s2
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 9] = fy*0; //s2
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 10] = fx*0;//s3
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 10] = fy*r2; //s3
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 0) + 11] = fx*0;//s4
                            dq_dintrinsics_nocore[(Nintrinsics-4)*(2*i + 1) + 11] = fy*r4; //s4

This does only the stuff I need: projection only (no geometric transformation), and gradients in respect to the point coordinates and distortions only. Gradients in respect to fxy and cxy are trivial, and I don't bother reporting them. So now I don't compile or link against OpenCV, my code builds and runs on Debian/sid and (surprisingly) it runs much faster than before. Apparently there was a lot of pointless overhead happening. Alright. Rant over.

19 June 2020

Russell Coker: Storage Trends

In considering storage trends for the consumer side I m looking at the current prices from MSY (where I usually buy computer parts). I know that other stores will have slightly different prices but they should be very similar as they all have low margins and wholesale prices are the main factor. Small Hard Drives Aren t Viable The cheapest hard drive that MSY sells is $68 for 500G of storage. The cheapest SSD is $49 for 120G and the second cheapest is $59 for 240G. SSD is cheaper at the low end and significantly faster. If someone needed about 500G of storage there s a 480G SSD for $97 which costs $29 more than a hard drive. With a modern PC if you have no hard drives you will notice that it s quieter. For anyone who s buying a new PC spending an extra $29 is definitely worthwhile for the performance, low power use, and silence. The cheapest 1TB disk is $69 and the cheapest 1TB SSD is $159. Saving $90 on the cost of a new PC probably isn t worth while. For 2TB of storage the cheapest options are Samsung NVMe for $339, Crucial SSD for $335, or a hard drive for $95. Some people would choose to save $244 by getting a hard drive instead of NVMe, but if you are getting a whole system then allocating $244 to NVMe instead of a faster CPU would probably give more benefits overall. Computer stores typically have small margins and computer parts tend to quickly either become cheaper or be obsoleted by better parts. So stores don t want to stock parts unless they will sell quickly. Disks smaller than 2TB probably aren t going to be profitable for stores for very long. The trend of SSD and NVMe becoming cheaper is going to make 2TB disks non-viable in the near future. NVMe vs SSD M.2 NVMe devices are at comparable prices to SATA SSDs. For some combinations of quality and capacity NVMe is about 50% more expensive and for some it s slightly cheaper (EG Intel 1TB NVMe being cheaper than Samsung EVO 1TB SSD). Last time I checked about half the motherboards on sale had a single M.2 socket so for a new workstation that doesn t need more than 2TB of storage (the largest NVMe that MSY sells) it wouldn t make sense to use anything other than NVMe. The benefit of NVMe is NOT throughput (even though NVMe devices can often sustain over 4GB/s), it s low latency. Workstations can t properly take advantage of this because RAM is so cheap ($198 for 32G of DDR4) that compiles etc mostly come from cache and because most filesystem writes on workstations aren t synchronous. For servers a large portion of writes are synchronous, for example a mail server can t acknowledge receiving mail until it knows that it s really on disk, so there s a lot of small writes that block server processes and the low latency of NVMe really improves performance. If you are doing a big compile on a workstation (the most common workstation task that uses a lot of disk IO) then the writes aren t synchronised to disk and if the system crashes you will just do all the compilation again. While NVMe doesn t give a lot of benefit over SSD for workstation use (I ve uses laptops with SSD and NVMe and not noticed a great difference) of course I still want better performance. ;) Last time I checked I couldn t easily buy a PCIe card that supported 2*NVMe cards, I m sure they are available somewhere but it would take longer to get and probably cost significantly more than twice as much. That means a RAID-1 of NVMe takes 2 PCIe slots if you don t have an M.2 socket on the motherboard. This was OK when I installed 2*NVMe devices on a server that had 18 disks and lots of spare PCIe slots. But for some systems PCIe slots are an issue. My home server has all PCIe slots used by a video card and Ethernet cards and the BIOS probably won t support booting from NVMe. It s a Dell server so I can t just replace the motherboard with one that has more PCIe slots and M.2 on the motherboard. As it s running nicely and doesn t need replacing any time soon I won t be using NVMe for home server stuff. Small Servers Most servers that I am responsible for have less than 2TB of storage. For my clients I now only recommend SSD storage for small servers and am recommending SSD for replacing any failed disks. My home server has 2*500G SSDs in a BTRFS RAID-1 for the root filesystem, and 3*4TB disks in a BTRFS RAID-1 for storing big files. I bought the SSDs when 500G SSDs were about $250 each and bought 2*4TB disks when they were about $350 each. Currently that server has about 3.3TB of space used and I could probably get it down to about 2.5TB if I deleted things I don t really need. If I was getting storage for that server now I d use 2*2TB SSDs and 3*1TB hard drives for the stuff that doesn t fit on SSDs (I have some spare 1TB disks that came with servers). If I didn t have spare hard drives I d get 3*2TB SSDs for that sort of server which would give 3TB of BTRFS RAID-1 storage. Last time I checked Dell servers had a card for supporting M.2 as an optional extra so Dells probably won t boot from NVMe without extra expense. Ars Technica has an informative article about WD selling SMR disks as NAS disks [1]. The Shingled Magnetic Recording technology allows greater storage density on a platter which leads to either larger capacity or cheaper disks but at the cost of lower write performance and apparently extremely bad latency in some situations. NAS disks are supposed to be low latency as the expectation is that they will be used in a RAID array and kicked out of the array if they have problems. There are reports of ZFS kicking SMR disks from RAID sets. I think this will end the use of hard drives for small servers. For a server you don t want to deal with this sort of thing, by definition when a server goes down multiple people will stop work (small server implies no clustering). Spending extra to get SSDs just to avoid the risk of unexpected SMR would be a good plan. Medium Servers The largest SSD and NVMe devices that are readily available are 2TB but 10TB disks are commodity items, there are reports of 20TB hard drives being available but I can t find anyone in Australia selling them. If you need to store dozens or hundreds of terabytes than hard drives have to be part of the mix at this time. There s no technical reason why SSDs larger than 10TB can t be made (the 2.5 SATA form factor has more than 5* the volume of a 2TB M.2 card) and it s likely that someone sells them outside the channels I buy from, but probably at a price higher than what my clients are willing to pay. If you want 100TB of affordable storage then a mid range server like the Dell PowerEdge T640 which can have up to 18*3.5 disks is good. One of my clients has a PowerEdge T630 with 18*3.5 disks in the 8TB-10TB range (we replace failed disks with the largest new commodity disks available, it used to have 6TB disks). ZFS version 0.8 introduced a Special VDEV Class which stores metadata and possibly small data blocks on faster media. So you could have some RAID-Z groups on hard drives for large storage and the metadata on a RAID-1 on NVMe for fast performance. For medium size arrays on hard drives having a find / operation take hours is not uncommon, for large arrays having it take days isn t that uncommon. So far it seems that ZFS is the only filesystem to have taken the obvious step of storing metadata on SSD/NVMe while bulk data is on cheap large disks. One problem with large arrays is that the vibration of disks can affect the performance and reliability of nearby disks. The ZFS server I run with 18 disks was originally setup with disks from smaller servers that never had ZFS checksum errors, but when disks from 2 small servers were put in one medium size server they started getting checksum errors presumably due to vibration. This alone is a sufficient reason for paying a premium for SSD storage. Currently the cost of 2TB of SSD or NVMe is between the prices of 6TB and 8TB hard drives, and the ratio of price/capacity for SSD and NVMe is improving dramatically while the increase in hard drive capacity is slow. 4TB SSDs are available for $895 compared to a 10TB hard drive for $549, so it s 4* more expensive on a price per TB. This is probably good for Windows systems, but for Linux systems where ZFS and special VDEVs is an option it s probably not worth considering. Most Linux user cases where 4TB SSDs would work well would be better served by smaller NVMe and 10TB disks running ZFS. I don t think that 4TB SSDs are at all popular at the moment (MSY doesn t stock them), but prices will come down and they will become common soon enough. Probably by the end of the year SSDs will halve in price and no hard drives less than 4TB will be viable. For rack mounted servers 2.5 disks have been popular for a long time. It s common for vendors to offer 2 versions of a rack mount server for 2.5 and 3.5 disks where the 2.5 version takes twice as many disks. If the issue is total storage in a server 4TB SSDs can give the same capacity as 8TB HDDs. SMR vs Regular Hard Drives Rumour has it that you can buy 20TB SMR disks, I haven t been able to find a reference to anyone who s selling them in Australia (please comment if you know who sells them and especially if you know the price). I expect that the ZFS developers will soon develop a work-around to solve the problems with SMR disks. Then arrays of 20TB SMR disks with NVMe for special VDEVs will be an interesting possibility for storage. I expect that SMR disks will be the majority of the hard drive market by 2023 if hard drives are still on the market. SSDs will be large enough and cheap enough that only SMR disks will offer enough capacity to be worth using. I think that it is a possibility that hard drives won t be manufactured in a few years. The volume of a 3.5 disk is significantly greater than that of 10 M.2 devices so current technology obviously allows 20TB of NVMe or SSD storage in the space of a 3.5 disk. If the price of 16TB NVMe and SSD devices comes down enough (to perhaps 3* the price of a 20TB hard drive) almost no-one would want the hard drive and it wouldn t be viable to manufacture them. It s not impossible that in a few years time 3D XPoint and similar fast NVM technologies occupy the first level of storage (the ZFS special VDEV , OS swap device, log device for database servers, etc) and NVMe occupies the level for bulk storage with no space left in the market for spinning media. Computer Cases For servers I expect that models supporting 3.5 storage devices will disappear. A 1RU server with 8*2.5 storage devices or a 2RU server with 16*2.5 storage devices will probably be of use to more people than a 1RU server with 4*3.5 or a 2RU server with 8*3.5 . My first IBM PC compatible system had a 5.25 hard drive, a 5.25 floppy drive, and a 3.5 floppy drive in 1988. My current PC is almost a similar size and has a DVD drive (that I almost never use) 5 other 5.25 drive bays that have never been used, and 5*3.5 drive bays that I have never used (I have only used 2.5 SSDs). It would make more sense to have PC cases designed around 2.5 and maybe 3.5 drives with no more than one 5.25 drive bay. The Intel NUC SFF PCs are going in the right direction. Many of them only have a single storage device but some of them have 2*M.2 sockets allowing RAID-1 of NVMe and some of them support ECC RAM so they could be used as small servers. A USB DVD drive costs $36, it doesn t make sense to have every PC designed around the size of an internal DVD drive that will probably only be used to install the OS when a $36 USB DVD drive can be used for every PC you own. The only reason I don t have a NUC for my personal workstation is that I get my workstations from e-waste. If I was going to pay for a PC then a NUC is the sort of thing I d pay to have on my desk.

[1] http://tinyurl.com/y8gglf5c

18 June 2020

Enrico Zini: Missing Qt5 designer library in cross-build development

This is part of a series of posts on compiling a custom version of Qt5 in order to develop for both amd64 and a Raspberry Pi. The problem While testing the cross-compiler, we noticed that the designer library was not being built. The designer library is needed to build designer plugins, which allow loading, dynamically at runtime, .ui interface files that use custom widgets. The error the customer got at runtime is: QFormBuilder was unable to create a custom widget of the class ' '; defaulting to base class 'QWidget'. The library with the custom widget implementation was correctly linked, and indeed the same custom widget was used by the application in other parts of its interface not loaded via .ui files. It turns out that it is not sufficient, and to load custom widgets automatically, QUiLoader wants to read their metadata from plugin libraries containing objects that implement the QDesignerCustomWidgetInterface interface. Sadly, building such a library requires using QT += designer, and the designer library, that was not being built by Qt5's build system. This looks very much like a Qt5 bug. A work around would be to subclass QUiLoader extending createWidget to teach it how to create the custom widgets we need. Unfortunately, the customer has many custom widgets. The investigation To find out why designer was not being built, I added -d to the qmake invocation at the end of qtbase/configure, and trawled through the 3.1G build output. The needle in the haystack seems to be here:

DEBUG 1: /home/build/armhf/qt-everywhere-src-5.15.0/qttools/src/designer/src/src.pro:18: SUBDIRS := uiplugin uitools lib components designer plugins
DEBUG 1: /home/build/armhf/qt-everywhere-src-5.15.0/qttools/src/designer/src/src.pro:23: calling qtNomakeTools(lib components designer plugins)

As far as I can understand, qtNomakeTools seems to be intended to disable building those components if QT_BUILD_PARTS doesn't contain tools. For cross-building, QT_BUILD_PARTS is libs examples, so designer does not get built. However, designer contains the library part needed for QDesignerCustomWidgetInterface and that really needs to be built. I assume that part should really be built as part of libs, not tools. The fixes/workarounds I tried removing designer from the qtNomakeTools invocation at qttools/src/designer/src/src.pro:23, to see if qttools/src/designer/src/designer/ would get built. It did get built, but then build failed with designer/src/designer and designer/src/uitools both claiming the designer plugin. I tried editing qttools/src/designer/src/uitools/uitools.pro not to claim the designer plugin when tools is not a build part. I added the tweaks to the Qt5 build system as debian/patches. 2 hours of build time later... make check is broken:

make[6]: Leaving directory '/home/build/armhf/qt-everywhere-src-5.15.0/qttools/src/designer/src/uitools'
make[5]: *** No rule to make target 'sub-components-check', needed by 'sub-designer-check'.  Stop.

But since make check doesn't do anything in this build, we can simply override dh_auto_test to skip that step. Finally, this patch builds a new executable, of an architecture that makes dh_shlibdeps struggle:

dpkg-shlibdeps: error: cannot find library libQt5DesignerComponentssystem.so.5 needed by debian/qtbase5system-armhf-dev/opt/qt5system-armhf/bin/designer (ELF format: 'elf32-little' abi: '0101002800000000'; RPATH: '')
dpkg-shlibdeps: error: cannot find library libQt5Designersystem.so.5 needed by debian/qtbase5system-armhf-dev/opt/qt5system-armhf/bin/designer (ELF format: 'elf32-little' abi: '0101002800000000'; RPATH: '')

And we can just skip running dh_shlibdeps on the designer executable. The result is in the qt5custom git repository.

17 June 2020

Ulrike Uhlig: On Language

Language is a tool of power In school, we read the philologist diary of Victor Klemperer about the changes in the German language during the Third Reich, LTI - Lingua Tertii Imperii, a book which makes it clear that the use of language is political, creates realities, and has reverse repercussions on concepts of an entire society. Language was one of the tools that supported Nazism in insiduously pervading all parts of society. Language shapes our concepts of society Around the same time, a friend of mine proposed to read Egalia's daughters by Gerd Brantenberg, a book in which gendered words were reversed: so that human becomes huwim, for example. This book made me take notice of gendered concepts that often go unnoticed. Language shapes the way we think and feel I spent a large part of my adult life in France, which confronted me with the realization that a language provides its speakers with certain concepts. If a concept does not exist in a language, people cannot easily feel or imagine this concept either. Back then (roughly 20 years ago), even though I was aware of gender inequality, I hated using gender neutral language because in German and French it felt unnatural, and, or so I thought, we were all alike. One day, at a party, we played a game that consisted in guessing people's professions by asking them Yes/No questions. Turns out that we were unable to guess that the woman we were talking with was a doctor, because we could simply not imagine this profession for a young woman. In French, docteur is male and almost nobody would use the word doctoresse, ou femme docteur. Unimaginable are also the concepts of words in German that have no equivalent in French or vice versa:

Sehnsucht composed of longing (sich sehnen) and obsession (Sucht). In English, this word is translated as longing. In French it is translated as nostalgie (nostalgia), but nostalgia is directed towards the past, while Sehnsucht in German can be used to designate a longing for people, places, food, even feelings, and can be used in all temporal directions. There are other approximate translations to French, for example aspiration.
Das Unheimliche is a German word and an essay by Sigmund Freud from 1919. The translation of the title had been subject to a lot of debate, before the text was published in French under the name "L'inqui tante tranget ", something that would translate to English as worrisome unfamiliarity. In English, there is a word for unheimlich, which is uncanny, however canny does not transport the German concept of heimlich which is related to home, familiarity, and secrecy.
D paysement. This French word is a negation of feeling home like in one's country (pays): it describes the, generally positively connoted, feelings one experiences when changing habits, or environment.

Or, to make all this a bit less serious, Italian has the word gattara (female) or gattaro (male), which one could translate to English roughly as cat person, most often designating old women who feed stray cats. But really, the way language shapes our concepts and ideas goes much further, as well explained by Lera Boroditsky in a talk in which she explains how language influences concepts of space, time, and blame, among other things. Building new models This quote by Buckminster Fuller is pinned on the wall over my desk:

You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete.

A change in language is such a new model: it can make oppression and inequalities visible. Words do not only describe our world, they are a vehicle of ideas, and utopias. Analyzing and criticizing our use of language means paving the way for ideas and concepts of inclusion, equality, and unity. You might be guessing at where am I getting at with this Right: I am in favor of acknowledging past mistakes, and replacing oppressive metaphors in computing. As noted in the IETF draft about Terminology, Power and Oppressive Language, by Niels Ten Oever and Mallory Knodel, the metaphors "master/slave" and "blacklist/whitelist" associate "white with good and black with evil [which] is known as the 'bad is black effect'", all the while being technically inaccurate. I acknowledge that this will take time. There is a lot of work to do.

16 June 2020

Ritesh Raj Sarraf: Kodi PS3 BD Remote

Setting up a Sony PS3 Blu-Ray Disc Remote Controller with Kodi TLDR; Since most of the articles on the internet were either obsolete or broken, I ve chosen to write these notes down in the form of a blog post so that it helps me now and in future, and hopefully others too.

Raspberry Pi All this time, I have been using the Raspberry Pi for my HTPC needs. The first RPi I acquired was in 2014 and I have been very very happy with the amount of support in the community and quality of the HTPC offering it has. I also appreciate the RPi s form factor and the power consumption limits. And then, to add more sugar to it, it uses a derivative of Debian, Raspbian, which was very familiar and feel good to me.

Raspberry Pi Issues So primarily, I use my RPi with Kodi. There are a bunch of other (daemon) services but the primary use case is HTPC only. RPi + Kodi has a very very annoying issue wherein it loses its audio pitch during video playback. The loss is so bad that the audio is barely audible. The workaround is to seek the video playback either way and then it comes back to its actual audio level, just to fade again in a while. My suspicion was that it may be a problem with Kodi. Or at least, Kodi would have a workaround in software. But unfortunately, I wasted a lot of time in dealing with my suspicion with no fruitful result. This started becoming a PITA over time. And it seems the issue is with the hardware itself because after I moved my setup to a regular laptop, the audio loss is gone.

Laptop with Kodi Since I had my old Lenovo Yoga 2 13 lying on all the time, it made sense to make some more use of it, using as the HTPC. This machine comes with a Micro-HDMI Out port, so it felt ideal for my High Definition video rendering needs. It comes stock with just Intel HD Video with good driver support in Linux, so it was quite quick and easy getting Kodi charged up and running on it. And as I mentioned above, the sound issues are not seen on this setup. Some added benefits are that I get to run stock Debian on this machine. And I must say a big THANK YOU to the Debian Multimedia Maintainers, who ve done a pretty good job maintaining Kodi under Debian.

HDMI CEC Only after I decommissioned my RPi, I came to notice how convenient the HDMI CEC functionality is. Turns out no standard laptops ship CEC functionality onto them. Even the case of my laptop, which has a Micro HDMI Out port, but still no CEC capabilities. As far as I know, the RPi came with the Pulse-Eight CEC module, so obvious first thought was to opt for a compatible external module of the same; but it comes with a nice price tag, me not willing to spend.

WiFi Remotes Kodi has very well implemented network interface for almost all its features. One could take the Yatse or Music Pump Kodi Remote Android applications that work very very well with Kodi. But wifi can be flaky some times. Especially, my experience with the Realtek network devices hasn t been very good. The driver support in Linux is okay but there are many firmware bugs to deal with. In my case, the machine will lose wifi signal/network every once in a while. And it turns out, for this machine, with this network device type, I m not the only one running into such problems. And to add to that, this is an UltraBook, which means it doesn t have an Ethernet port. So I ve had not much choice other than to live and ~~suffer~~ deal with it. The WiFi chip also provides the Bluetooth module, which so far I had not used much. From my /etc/modprobe.d/blacklist-memstick.conf, all relevant BT modules were added to the blacklist, all this time.

rrs@lenovo:~$ cat /etc/modprobe.d/blacklist-memstick.conf 
blacklist memstick
blacklist rtsx_usb_ms
# And bluetooth too
#blacklist btusb
#blacklist btrtl
#blacklist btbcm
#blacklist btintel
#blacklist bluetooth
21:21

Also to keep in mind is that the driver for my card gives a very misleading kernel message, which is one of the many reasons for this blog post, so that I don t forget it a couple of months later. The missing firmware error message is okay to ignore, as per this upstream comment.

Jun 14 17:17:08 lenovo kernel: usbcore: registered new interface driver btusb
Jun 14 17:17:08 lenovo systemd[1]: Mounted /boot/efi.
Jun 14 17:17:08 lenovo kernel: Bluetooth: hci0: RTL: examining hci_ver=06 hci_rev=000b lmp_ver=06 lmp_subver=8723
Jun 14 17:17:08 lenovo kernel: Bluetooth: hci0: RTL: rom_version status=0 version=1
Jun 14 17:17:08 lenovo kernel: Bluetooth: hci0: RTL: loading rtl_bt/rtl8723b_fw.bin
Jun 14 17:17:08 lenovo kernel: bluetooth hci0: firmware: direct-loading firmware rtl_bt/rtl8723b_fw.bin
Jun 14 17:17:08 lenovo kernel: Bluetooth: hci0: RTL: loading rtl_bt/rtl8723b_config.bin
Jun 14 17:17:08 lenovo kernel: bluetooth hci0: firmware: failed to load rtl_bt/rtl8723b_config.bin (-2)
Jun 14 17:17:08 lenovo kernel: firmware_class: See https://wiki.debian.org/Firmware for information about missing firmware
Jun 14 17:17:08 lenovo kernel: bluetooth hci0: Direct firmware load for rtl_bt/rtl8723b_config.bin failed with error -2
Jun 14 17:17:08 lenovo kernel: Bluetooth: hci0: RTL: cfg_sz -2, total sz 22496

This device s network + bt are on the same chip.

01:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8723BE PCIe Wireless Network Adapter

And then, when the btusb module is initialed (along with the misleading driver message), you ll get the following in your USB device listing

Bus 002 Device 005: ID 0bda:b728 Realtek Semiconductor Corp. Bluetooth Radio

Sony PlayStation 3 BD Remote Almost 10 years ago, I bought the PS3 and many of its accessories. The remote has just been rotting in the shelf. It had rusted so bad that it is better described with these pics.

Rusted inside

Rusted inside and cover

Rusted spring

The rust was so much that the battery holding spring gave up. A little bit scrubbing and cleaning has gotten it working. I hope it lasts for some time before I find time to open it up and give it a full clean-up.

Pairing the BD Remote to laptop Honestly, with the condition of the hardware and software on both ends, I did not have much hopes of getting this to work. And in all the years on my computer usage, I hardly recollect much days when I ve made use of BT. Probably, because the full BT stack wasn t that well integrated in Linux, earlier. And I mostly used to disable them in hardware and software to save on battery. All yielded results from the internet talked about tools/scripts that were either not working, pointing to broken links etc. These days, bluez comes with a nice utility, bluetoothctl. It was a nice experience using it. First, start your bluetooth service and ensure that the device talks well with the kernel

rrs@lenovo:~$ systemctl status bluetooth                                                                                                          
  bluetooth.service - Bluetooth service                                                                                                           
     Loaded: loaded (/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)                                                      
     Active: active (running) since Mon 2020-06-15 12:54:58 IST; 3s ago                                                                           
       Docs: man:bluetoothd(8)                                                                                                                    
   Main PID: 310197 (bluetoothd)                                                                                                                  
     Status: "Running"                                                                                                                            
      Tasks: 1 (limit: 9424)                                                                                                                      
     Memory: 1.3M                                                                                                                                 
     CGroup: /system.slice/bluetooth.service                                                                                                      
              310197 /usr/lib/bluetooth/bluetoothd                                                                                               
                                                                                                                                                  
Jun 15 12:54:58 lenovo systemd[1]: Starting Bluetooth service...                                                                                  
Jun 15 12:54:58 lenovo bluetoothd[310197]: Bluetooth daemon 5.50                                                                                  
Jun 15 12:54:58 lenovo systemd[1]: Started Bluetooth service.                                                                                     
Jun 15 12:54:58 lenovo bluetoothd[310197]: Starting SDP server                                                                                    
Jun 15 12:54:58 lenovo bluetoothd[310197]: Bluetooth management interface 1.15 initialized                                                        
Jun 15 12:54:58 lenovo bluetoothd[310197]: Sap driver initialization failed.                                                                      
Jun 15 12:54:58 lenovo bluetoothd[310197]: sap-server: Operation not permitted (1)                                                                
12:55

Next, then is to discover and connect to your device

rrs@lenovo:~$ bluetoothctl 
Agent registered
[bluetooth]# devices
Device E6:3A:32:A4:31:8F MI Band 2
Device D4:B8:FF:43:AB:47 MI RC
Device 00:1E:3D:10:29:0F BD Remote Control
[CHG] Device 00:1E:3D:10:29:0F Connected: yes
[BD Remote Control]# info 00:1E:3D:10:29:0F
Device 00:1E:3D:10:29:0F (public)
        Name: BD Remote Control
        Alias: BD Remote Control
        Class: 0x0000250c
        Paired: no
        Trusted: yes
        Blocked: no
        Connected: yes
        LegacyPairing: no
        UUID: Human Interface Device... (00001124-0000-1000-8000-00805f9b34fb)
        UUID: PnP Information           (00001200-0000-1000-8000-00805f9b34fb)
        Modalias: usb:v054Cp0306d0100
[bluetooth]#

In case of the Sony BD Remote, there s no need to pair. In fact, trying to pair fails. It prompts for the PIN code, but neither 0000 or 1234 are accepted. So, the working steps so far are to Trust the device and then Connect the device. For the sake of future use, I also populated /etc/bluetooth/input.conf based on suggestions on the internet. Note: The advertised keymappings in this config file do not work. Note: I m only using it for the power saving measures in instructing the BT connection to sleep after 3 minutes.

rrs@priyasi:/tmp$ cat input.conf 
# Configuration file for the input service
# This section contains options which are not specific to any
# particular interface
[General]
# Set idle timeout (in minutes) before the connection will
# be disconnect (defaults to 0 for no timeout)
IdleTimeout=3
# Enable HID protocol handling in userspace input profile
# Defaults to false (HIDP handled in HIDP kernel module)
#UserspaceHID=true
# Limit HID connections to bonded devices
# The HID Profile does not specify that devices must be bonded, however some
# platforms may want to make sure that input connections only come from bonded
# device connections. Several older mice have been known for not supporting
# pairing/encryption.
# Defaults to false to maximize device compatibility.
#ClassicBondedOnly=true
# LE upgrade security
# Enables upgrades of security automatically if required.
# Defaults to true to maximize device compatibility.
#LEAutoSecurity=true
#
#[00:1E:3D:10:29:0F]
[2c:33:7a:8e:d6:30]
[PS3 Remote Map]
# When the 'OverlayBuiltin' option is TRUE (the default), the keymap uses
# the built-in keymap as a starting point.  When FALSE, an empty keymap is
# the starting point.
#OverlayBuiltin = TRUE
#buttoncode = keypress    # Button label = action with default key mappings
#OverlayBuiltin = FALSE
0x16 = KEY_ESC            # EJECT = exit
0x64 = KEY_MINUS          # AUDIO = cycle audio tracks
0x65 = KEY_W              # ANGLE = cycle zoom mode
0x63 = KEY_T              # SUBTITLE = toggle subtitles
0x0f = KEY_DELETE         # CLEAR = delete key
0x28 = KEY_F8             # /TIME = toggle through sleep
0x00 = KEY_1              # NUM-1
0x01 = KEY_2              # NUM-2
0x02 = KEY_3              # NUM-3
0x03 = KEY_4              # NUM-4
0x04 = KEY_5              # NUM-5
0x05 = KEY_6              # NUM-6
0x06 = KEY_7              # NUM-7
0x07 = KEY_8              # NUM-8
0x08 = KEY_9              # NUM-9
0x09 = KEY_0              # NUM-0
0x81 = KEY_F2             # RED = red
0x82 = KEY_F3             # GREEN = green
0x80 = KEY_F4             # BLUE = blue
0x83 = KEY_F5             # YELLOW = yellow
0x70 = KEY_I              # DISPLAY = show information
0x1a = KEY_S              # TOP MENU = show guide
0x40 = KEY_M              # POP UP/MENU = menu
0x0e = KEY_ESC            # RETURN = back/escape/cancel
0x5c = KEY_R              # TRIANGLE/OPTIONS = cycle through recording options
0x5d = KEY_ESC            # CIRCLE/BACK = back/escape/cancel
0x5f = KEY_A              # SQUARE/VIEW = Adjust Playback timestretch
0x5e = KEY_ENTER          # CROSS = select
0x54 = KEY_UP             # UP = Up/Skip forward 10 minutes
0x56 = KEY_DOWN           # DOWN = Down/Skip back 10 minutes
0x57 = KEY_LEFT           # LEFT = Left/Skip back 5 seconds
0x55 = KEY_RIGHT          # RIGHT = Right/Skip forward 30 seconds
0x0b = KEY_ENTER          # ENTER = select
0x5a = KEY_F10            # L1 = volume down
0x58 = KEY_J              # L2 = decrease the play speed
0x51 = KEY_HOME           # L3 = commercial skip previous
0x5b = KEY_F11            # R1 = volume up
0x59 = KEY_U              # R2 = increase the play speed
0x52 = KEY_END            # R3 = commercial skip next
0x43 = KEY_F9             # PS button = mute
0x50 = KEY_M              # SELECT = menu (as per PS convention)
0x53 = KEY_ENTER          # START = select / Enter (matches terminology in mythwelcome)
0x30 = KEY_PAGEUP         # PREV = jump back (default 10 minutes)
0x76 = KEY_J              # INSTANT BACK (newer RCs only) = decrease the play speed
0x75 = KEY_U              # INSTANT FORWARD (newer RCs only) = increase the play speed
0x31 = KEY_PAGEDOWN       # NEXT = jump forward (default 10 minutes)
0x33 = KEY_COMMA          # SCAN BACK =  decrease scan forward speed / play
0x32 = KEY_P              # PLAY = play/pause
0x34 = KEY_DOT            # SCAN FORWARD decrease scan backard speed / increase playback speed; 3x, 5, 10, 20, 30, 60, 120, 180
0x60 = KEY_LEFT           # FRAMEBACK = Left/Skip back 5 seconds/rewind one frame
0x39 = KEY_P              # PAUSE = play/pause
0x38 = KEY_P              # STOP = play/pause
0x61 = KEY_RIGHT          # FRAMEFORWARD = Right/Skip forward 30 seconds/advance one frame
0xff = KEY_MAX
21:48

I have not spent much time finding out why not all the key presses work. Especially, given that most places on the internet mention these mappings. For me, some of the key scan codes aren t even reported. For keys like L1, L2, L3, R1, R2, R3, Next_Item, Prev_Item, they generate no codes in the kernel. If anyone has suggestions, ideas or fixes, I d appreciate if you can drop a comment or email me privately. But given my limited use to get a simple remote ready, to be usable with Kodi, I was apt with only some of the keys working.

Mapping the keys in Kodi With the limited number of keys detected, mapping those keys to what Kodi could use was the next step. Kodi has a very nice and easy to use module, Keymap Editor. It is very simple to use and map detected keys to functionalities you want. With it, I was able to get a functioning remote to use with my Kodi HTPC setup.

Update: Wed Jun 17 11:38:20 2020 One annoying problem that breaks the overall experience is the following bug on the driver side, that results in connections not being established instantly. Once the device goes into sleep mode, in random attempts, waking up and re-establishing a BT connection can be multi-poll affair. This can last from a couple of seconds to well over minute. Random suggestions on the internet mention disabling the autosuspend functionality for the device in the driver with btusb.enable_autosuspend=n, but that did not help in this case. Given that this device is enumberated over the USB Bus, it probably needs this feature applied to the whole USB tree of the device s chain. Something to investigate over the weekend.

Jun 16 20:41:23 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 7
Jun 16 20:41:43 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 8
Jun 16 20:41:59 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 9
Jun 16 20:42:18 lenovo kernel: input: BD Remote Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:10/0005:054C:030>
Jun 16 20:42:18 lenovo kernel: sony 0005:054C:0306.0006: input,hidraw1: BLUETOOTH HID v1.00 Gamepad [BD Remote Control] on 2c:33:7a:8e:d6:30
Jun 16 20:51:59 lenovo kernel: input: BD Remote Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:11/0005:054C:030>
Jun 16 20:51:59 lenovo kernel: sony 0005:054C:0306.0007: input,hidraw1: BLUETOOTH HID v1.00 Gamepad [BD Remote Control] on 2c:33:7a:8e:d6:30
Jun 16 21:05:55 lenovo rtkit-daemon[1723]: Supervising 3 threads of 1 processes of 1 users.
Jun 16 21:05:55 lenovo rtkit-daemon[1723]: Successfully made thread 32747 of process 1646 owned by '1000' RT at priority 5.
Jun 16 21:05:55 lenovo rtkit-daemon[1723]: Supervising 4 threads of 1 processes of 1 users.
Jun 16 21:05:56 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 12
Jun 16 21:06:12 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 1
Jun 16 21:06:34 lenovo kernel: Bluetooth: hci0: ACL packet for unknown connection handle 2
Jun 16 21:06:59 lenovo kernel: input: BD Remote Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-7:1.0/bluetooth/hci0/hci0:3/0005:054C:0306>
Jun 16 21:06:59 lenovo kernel: sony 0005:054C:0306.0008: input,hidraw1: BLUETOOTH HID v1.00 Gamepad [BD Remote Control] on 2c:33:7a:8e:d6:30

Others There s a package, kodi-eventclients-ps3, which can be used to talk to the BD Remote. Unfortunately, it isn t up-to-date. When trying to make use of it, I ran into a couple of problems. First, the easy one is:

rrs@lenovo:~/ps3pair$ kodi-ps3remote localhost 9777
usr/share/pixmaps/kodi//bluetooth.png
Traceback (most recent call last):
  File "/usr/bin/kodi-ps3remote", line 220, in <module>
  File "/usr/bin/kodi-ps3remote", line 208, in main
    xbmc.connect(host, port)
    packet = PacketHELO(self.name, self.icon_type, self.icon_file)
  File "/usr/lib/python3/dist-packages/kodi/xbmcclient.py", line 285, in __init__
    with open(icon_file, 'rb') as f:
11:16         => 1

This one was simple as it was just a broken path. The second issue with the tool is a leftover from python2 to python3 conversion.

rrs@lenovo:/etc/bluetooth$ kodi-ps3remote localhost
/usr/share/pixmaps/kodi//bluetooth.png
Searching for BD Remote Control
(Hold Start + Enter on remote to make it discoverable)
Redmi (E8:5A:8B:73:57:44) in range
Living Room TV (E4:DB:6D:24:23:E9) in range
Could not find BD Remote Control. Trying again...
Searching for BD Remote Control
(Hold Start + Enter on remote to make it discoverable)
Living Room TV (E4:DB:6D:24:23:E9) in range
Redmi (E8:5A:8B:73:57:44) in range
Could not find BD Remote Control. Trying again...
Searching for BD Remote Control
(Hold Start + Enter on remote to make it discoverable)
BD Remote Control (00:1E:3D:10:29:0F) in range
Found BD Remote Control with address 00:1E:3D:10:29:0F
Attempting to pair with remote
Remote Paired.
Traceback (most recent call last):
  File "/usr/bin/kodi-ps3remote", line 221, in <module>
    main()
  File "/usr/bin/kodi-ps3remote", line 212, in main
    if process_keys(remote, xbmc):
  File "/usr/bin/kodi-ps3remote", line 164, in process_keys
    keycode = data.encode("hex")[10:12]
AttributeError: 'bytes' object has no attribute 'encode'
11:24         => 1

Fixing that too did not give me the desired result on using the BD Remote in the way I want. So eventually, I gave up and used Kodi s Keymap Editor instead.

Next Next in line, when I can manage to get some free time, is to improve the Kodi Video Scraper to have a fallback mode. Currently, for files where it cannot determine the content, it reject the file resulting in those files not showing up in your collection at all. A better approach would have been to have a fallback mode, that when the scraper cannot determine the content, it should fallback to using the filename scraper

15 June 2020

Mark Brown: Book Club: Zettlekasten

Recently I was part of a call with Daniel and Lars to discuss Zettelkasten, a system for building up a cross-referenced archive of notes to help with research and study that has been getting a lot of discussion recently, the key thing being the building of links between ideas. Tomas Vik provided an overview of the process that we all found very helpful, and the information vs knowledge picture in Eugene Yan s blog on the topic (by @gapingvoid) really helped us crystalize the goals. It s not at all new and as Lars noted has a lot of similarities with a wikis in terms of what it produces but it couples this with an emphasis on the process and constant generation of new entries which Daniel found similar to some of the Getting Things Done recommendations. We all liked the emphasis on constant practice and how that can help build skills around effective note taking, clear writing and building links between ideas. Both Daniel and Lars already have note taking practicies that they find useful, combinations of journalling and building up collections of notes of learnings over time, and felt that there could be value in integrating aspects of Zettelkasten into these practices so we talked quite a bit about how that could be done. There was a consensus that journalling is useful so the main idea we had was to keep maintaining the journal, using that as an inbox and setting aside time to write entries into a Zettelkasten. This is also a useful way to approach recording things when away from a computer, taking notes and then writing them up later. Daniel suggested that one way to migrate existing notes might be to simply start anew, moving things over from old notes as required and then after a suitably long period (for example a year) review anything that was left and migrate anything that was left. We were all concerned about the idea of using any of the non-free solutions for something that is intended to be used long term, especially where the database isn t in an easily understood format. Fortunately there are free software tools like Zettlr which seem to address these concerns well. This was a really useful discussion, it really helps to bounce ideas off each other and this was certainly an interesting topic to learn about with some good ideas which will hopefully be helpful to us.

14 June 2020

Evgeni Golov: naked pings 2020

ajax' post about "ping" etiquette is over 10 years old, but holds true until this day. So true, that my IRC client at work has a script, that will reply with a link to it each time I get a naked ping. But IRC is not the only means of communication. There is also mail, (video) conferencing, and GitHub/GitLab. Well, at least in the software engineering context. Oh and yes, it's 2020 and I still (proudly) have no Slack account. Thankfully, (naked) pings are not really a thing for mail or conferencing, but I see an increasing amount of them on GitHub and it bothers me, a lot. As there is no direct messaging on GitHub, you might rightfully ask why, as there is always context in form of the issue or PR the ping happened in, so lean back an listen ;-) notifications become useless While there might be context in the issue/PR, there is none (besides the title) in the notification mail, and not even the title in the notification from the Android app (which I have installed as I use it lot for smaller reviews). So the ping will always force a full context switch to open the web view of the issue in question, removing the possibility to just swipe away the notification/mail as "not important right now". even some context is not enough context Even after visiting the issue/PR, the ping quite often remains non-actionable. Do you want me to debug/fix the issue? Review the PR? Merge it? Close it? I don't know! The only actionable ping is when the previous message is directed at me and has an actionable request in it and the ping is just a reminder that I have to do it. And even then, why not write "hey @evgeni, did you have time to process my last question?" or something similar? BTW, this is also what I dislike about ajax' minimal example "ping re bz 534027" - what am I supposed to do with that BZ?! why me anyways?! Unless I am the only maintainer of a repo or the author of the issue/PR, there is usually no reason to ping me directly. I might be sick, or on holiday, or currently not working on that particular repo/topic or whatever. Any of that will result in you thinking that your request will be prioritized, while in reality it won't. Even worse, somebody might come across it, see me mentioned and think "ok, that's Evgeni's playground, I'll look elsewhere". Most organizations have groups of people working on specific topics. If you know the group name and have enough permissions (I am not exactly sure which, just that GitHub have limits to avoid spam, sorry) you can ping @organization/group and everyone in that group will get a notification. That's far from perfect, but at least this will get the attention of the right people. Sometimes there is also a bot that will either automatically ping a group of people or you can trigger to do so. Oh, and I'm getting paid for work on open source. So if you end up pinging me in a work-related repository, there is a high chance I will only process that during work hours, while another co-worker might have been available to help you out almost immediately. be patient Unless we talked on another medium before and I am waiting for it, please don't ping directly after creation of the issue/PR. Maintainers get notifications about new stuff and will triage and process it at some point. conclusion If you feel called out, please don't take it personally. Instead, please try to provide as much actionable information as possible and be patient, that's the best way to get a high quality result. I will ignore pings where I don't immediately know what to do, and so should you. one more thing Oh, and if you ping me on IRC, with context, and then disconnect before I can respond In the past you would sometimes get a reply by mail. These days the request will be most probably ignored. I don't like talking to the void. Sorry.

12 June 2020

Ulrike Uhlig: The right to demand change

Two women sit in an office, one asks: "What's the difference between being assertive and being aggressive?" The other replies: "Your gender." (Cartoon by Judy Horacek, 1999.) When a person of a marginalized group (read: a person with less privilege, a person with lower rank) is being framed and blamed as being aggressive, she is being told that her behavior is unacceptable. Marginalized people have learnt that they need to comply to fit, and are likely to suppress their feelings. By being framed as aggressive, the marginalized person is also being told that what they are saying cannot be listened to because the way they are saying it does not comply with expectations. There is a word for this: tone policing. This great comic by Robot Hugs has all the important details. Tone policing is a silencing tactic in which privileged participants of a discussion one-sidedly define the terms of the conversation. This tactic has the interesting side effect of shifting the responsibility to prove that one is not aggressive, hostile, explosive, a minefield, etc. to the person being framed and blamed - proving that one is worthy to be listened to. (Some of those words are actual quotes taken from real life.) Years ago, I worked in a company in which my female developer colleague would put herself in a state of overly expressed sorriness, all the while pretending to be stupid and helpless whenever she needed to ask anything from the sysadmins. When I confronted her with that, she replied: "I do it because it works." In the same company, another woman who generally asked assertively for what she needed ended up being insulted by one of the project managers using the word "dominatrix". While the example comes from my own experience, this kind of thing happens across any oppression/privilege boundaries. In some conversations, be they verbal or written, frustration and anger of one person are sometimes being mistaken by the communication partner for aggressiveness. Why is this happening? Asking a person with privilege to see, question, or change their behavior, questions their privilege. I'm thinking that it might be that most people think of themselves as "being good" and when they are being asked to question themselves or their behavior, their self-image is being challenged. "Me? But I did not do anything wrong! It's certainly not my fault if you are being oppressed! I sacrificed myself to reach my current position in life!" This comic by Toby Morris, "On a Plate", explains it quite nicely. So are we stuck with seeing conversations derail? I'd argue instead that while anger and frustration are unpleasant feelings, they're important: they show us that our boundaries have been crossed, that we want something to change, to stop, or that we need something different right now. We have the right to be angry and to demand change.

11 June 2020

Antoine Beaupr : CVE-2020-13777 GnuTLS audit: be scared

So CVE-2020-13777 came out while I wasn't looking last week. The GnuTLS advisory (GNUTLS-SA-2020-06-03) is pretty opaque so I'll refer instead to this tweet from @FiloSottile (Go team security lead):

PSA: don't rely on GnuTLS, please. CVE-2020-13777 Whoops, for the past 10 releases most TLS 1.0 1.2 connection could be passively decrypted and most TLS 1.3 connections intercepted. Trivially. Also, TLS 1.2 1.0 session tickets are awful.

You are reading this correctly: supposedly encrypted TLS connections made with affected GnuTLS releases are vulnerable to passive cleartext recovery attack (and active for 1.3, but who uses that anyways). That is extremely bad. It's pretty close to just switching everyone to HTTP instead of HTTPS, more or less. I would have a lot more to say about the security of GnuTLS in particular -- and security in general -- but I am mostly concerned about patching holes in the roof right now, so this article is not about that. This article is about figuring out what, exactly, was exposed in our infrastructure because of this.

Affected packages Assuming you're running Debian, this will show a list of packages that Depends on GnuTLS:

apt-cache --installed rdepends libgnutls30   grep '^ '   sort -u

This assumes you run this only on hosts running Buster or above. Otherwise you'll need to figure out a way to pick machines running GnuTLS 3.6.4 or later. Note that this list only first level dependencies! It is perfectly possible that another package uses GnuTLS without being listed here. For example, in the above list I have libcurl3-gnutls, so the be really thorough, I would actually need to recurse down the dependency tree. On my desktop, this shows an "interesting" list of targets:

apt
cadaver - AKA WebDAV
curl & wget
fwupd - another attack on top of this one
git (through the libcurl3-gnutls dependency)
mutt - all your emails
weechat - your precious private chats

Arguably, fetchers like apt, curl, fwupd, and wget rely on HTTPS for "authentication" more than secrecy, although apt has its own OpenPGP-based authentication so that wouldn't matter anyways. Still, this is truly distressing. And I haven't mentioned here things like gobby, network-manager, systemd, and others - the scope of this is broad. Hell, even good old lynx links against GnuTLS. In our infrastructure, the magic command looks something like this:

cumin -o txt -p 0  'F:lsbdistcodename=buster' "apt-cache --installed rdepends libgnutls30   grep '^ '   sort -u"   tee gnutls-rdepds-per-host   awk ' print $NF '   sort   uniq -c   sort -n

There, the result is even more worrisome, as those important packages seem to rely on GnuTLS for their transport security:

mariadb - all MySQL traffic and passwords
mandos - full disk encryption
slapd - LDAP passwords

mandos is especially distressing although it's probably not vulnerable because it seems it doesn't store the cleartext -- it's encrypted with the client's OpenPGP public key -- so the TLS tunnel never sees the cleartext either. Other reports have also mentioned the following servers link against GnuTLS and could be vulnerable:

exim
rsyslog
samba
various VNC implementations

Not affected Those programs are not affected by this vulnerability:

`apache2`

`gnupg`

`python`

`nginx`

`openssh`

This list is not exhaustive, naturally, but serves as an example of common software you don't need to worry about. The vulnerability only exists in GnuTLS, as far as we know, so programs linking against other libraries are not vulnerable. Because the vulnerability affects session tickets -- and those are set on the server side of the TLS connection -- only users of GnuTLS as a server are vulnerable. This means, for example, that while `weechat` uses GnuTLS, it will only suffer from the problem when acting as a server (which it does, in relay mode) or, of course, if the remote IRC server also uses GnuTLS. Same with apt, curl, wget, or git: it is unlikely to be a problem because it is only used as a client; the remote server is usually a webserver -- not git itself -- when using TLS.

Caveats Keep in mind that it's not because a package links against GnuTLS that it uses it. For example, I have been told that, on Arch Linux, if both GnuTLS and OpenSSL are available, the `mutt` package will use the latter, so it's not affected. I haven't confirmed that myself nor have I checked on Debian. Also, because it relies on session tickets, there's a time window after which the ticket gets cycled and properly initialized. But that is apparently 6 hours by default so it is going to protect only really long-lasting TLS sessions, which are uncommon, I would argue. My audit is limited. For example, it might have been better to walk the shared library dependencies directly, instead of relying on Debian package dependencies.

Other technical details It seems the vulnerability might have been introduced in this merge request, itself following a (entirely reasonable) feature request to make it easier to rotate session tickets. The merge request was open for a few months and was thoroughly reviewed by a peer before being merged. Interestingly, the vulnerable function (_gnutls_initialize_session_ticket_key_rotation), explicitly says:

 * This function will not enable session ticket keys on the server side. That is done
 * with the gnutls_session_ticket_enable_server() function. This function just initializes
 * the internal state to support periodical rotation of the session ticket encryption key.

In other words, it thinks it is not responsible for session ticket initialization, yet it is. Indeed, the merge request fixing the problem unconditionally does this:

memcpy(session->key.initial_stek, key->data, key->size);

I haven't reviewed the code and the vulnerability in detail, so take the above with a grain of salt. The full patch is available here. See also the upstream issue 1011, the upstream advisory, the Debian security tracker, and the Redhat Bugzilla.

Moving forward The impact of this vulnerability depends on the affected packages and how they are used. It can range from "meh, someone knows I downloaded that Debian package yesterday" to "holy crap my full disk encryption passwords are compromised, I need to re-encrypt all my drives", including "I need to change all LDAP and MySQL passwords". It promises to be a fun week for some people at least. Looking ahead, however, one has to wonder whether we should follow @FiloSottile's advice and stop using GnuTLS altogether. There are at least a few programs that link against GnuTLS because of the OpenSSL licensing oddities but that has been first announced in 2015, then definitely and clearly resolved in 2017 -- or maybe that was in 2018? Anyways it's fixed, pinky-promise-I-swear, except if you're one of those weirdos still using GPL-2, of course. Even though OpenSSL isn't the simplest and secure TLS implementation out there, it could preferable to GnuTLS and maybe we should consider changing Debian packages to use it in the future. But then again, the last time something like this happened, it was Heartbleed and GnuTLS wasn't affected, so who knows... It is likely that people don't have OpenSSL in mind when they suggest moving away from GnuTLS and instead think of other TLS libraries like mbedtls (previously known as PolarSSL), NSS, BoringSSL, LibreSSL and so on. Not that those are totally sinless either... "This is fine", as they say...

10 June 2020

Joey Hess: bracketing and async exceptions in haskell

I've been digging into async exceptions in haskell, and getting more and more concerned. In particular, bracket seems to be often used in ways that are not async exception safe. I've found multiple libraries with problems. Here's an example:

withTempFile a = bracket setup cleanup a
  where
    setup = openTempFile "/tmp" "tmpfile"
    cleanup (name, h) = do
        hClose h
        removeFile name

This looks reasonably good, it makes sure to clean up after itself even when the action throws an exception. But, in fact that code can leave stale temp files lying around. If the thread receives an async exception when hClose is running, it will be interrupted before the file is removed. We normally think of bracket as masking exceptions, but it doesn't prevent async exceptions in all cases. See Control.Exception on "interruptible operations", which can receive async exceptions even when other exceptions are masked. It's a bit surprising, but hClose is such an interruptable operation, because it flushes the write buffer. The only way to know is to read the code. It can be quite hard to determine if an operation is interruptable, since it can come down to whether it retries a STM transaction, or uses a MVar that is not always full. I've been auditing libraries and I often have to look at code several dependencies away, and even then may not be sure if a library has this problem.

process's withCreateProcess could fail to wait on the process, leaving a zombie. Might also leak file descriptors?
http-client's withResponse might fail to close a network connection. (If a MVar happened to be empty when it's called.) Worth noting that there are plenty of examples of using http-client to eg, race downloading two urls and cancel the slower download. Which is just the kind of use of an async exception that could cause a problem.
persistent's withSqlPool and withSqlConn might fail to clean up, when used with persistent-postgresql. (If another thread is using the connection and so a MVar over in postgresql-simple is empty.)
concurrent-output has some locking code that is not async exception safe. (My library, so I've fixed part of it, and hope to fix the rest.)

So far, around half of the libraries I've looked at, that use bracket or onException or the like probably have this problem. What can libraries do?

Document whether these things are async exception safe. Or perhaps there should be an expectation that "withFoo" always is, but if so the Haskell comminity has some work ahead of it.
Use finally. Good mostly in simple situations; more complicated things would be hard to write this way.
```
hClose h  finally  removeFile name
```
Use uninterruptibleMask, but it's a big hammer and is often not the right tool for the job. If the operation takes a while to run, the program will not respond to ctrl-c during that time.
May be better to run the actions in worker threads, to insulate them from receiving any async exceptions.
```
bracketInsulated :: IO a -> (a -> IO b) -> (a -> IO c) -> IO c
bracketInsulated a b = bracket
  (uninterruptibleMask $ \u -> async (u a) >>= u . wait)
  (\v -> uninterruptibleMask $ \u -> async (u (b v)) >>= u . wait)
```
(Note use of uninterruptibleMask here in case async itself does an interruptable operation. My first version got that wrong.. This is hard!)

My impression of the state of things now is that you should be very cautious using race or cancel or withAsync or the like, unless the thread is small and easy to audit for these problems. Kind of a shame, since I had wanted to be able to cancel a thread that is big and sprawling and uses all the libraries mentioned above.

This work was sponsored by Jake Vosloo and Graham Spencer on Patreon.

Dirk Eddelbuettel: binb 0.0.6: Small enhancements

The sixth release of the binb package is now on CRAN. binb regroups four rather nice themes for writing LaTeX Beamer presentations much more easily in (R)Markdown. As a teaser, a quick demo combining all four themes follows; documentation and examples are in the package.

Via two contributed PRs, this releases adds titlepage support via the YAML header for Metropolis, and suppresses nags about the changed natbib default. A little polish on the README and Travis rounds everything off.

Changes in binb version 0.0.6 (2020-06-10)

Support for YAML option titlegraphic was added in Metropolis (Andras Scraka in #23).

The README.md file received another badge (Dirk).

The natbib default value was updated to accomodate rmarkdown (Joseph Stachelek in #26).

Travis now uses R 4.0.0 and 'bionic' (Dirk).

CRANberries provides a summary of changes to the previous version. For questions or comments, please use the issue tracker at GitHub. If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Jonathan Dowland: Template Haskell and Stream-processing programs

I've written about what Template Haskell is, and given an example of what it can be used for, it's time to explain why I was looking at it in the context of my PhD work. Encoding stream-processing programs StrIoT is an experimental distributed stream-processing system that myself and others are building in order to explore our research questions. A user of StrIoT writes a stream-processing program, using a set of 8 functional operators provided for the purpose. A simple example is

streamFn :: Stream Int -> Stream Int
streamFn = streamFilter (<15)
         . streamFilter (>5)
         . streamMap (*2)

Our system is distributed: we take a stream-processing program and partition it into sub-programs, which are distributed to and run on separate nodes (perhaps cloud instances, or embedded devices like Raspberry Pis etc.). In order to do that, we need to be able to manipulate the stream-processing program as data. We've initially opted for a graph data-structure, with the vertices in the graph defined as

data StreamVertex = StreamVertex
      vertexId   :: Int
    , operator   :: StreamOperator
    , parameters :: [String]
    , intype     :: String
    , outtype    :: String
      deriving (Eq,Show)

A stream-processing program encoded this way, equivalent to the first example

path [ StreamVertex 0 Map    ["(*2)"]  "Int" "Int"
     , StreamVertex 1 Filter ["(>5)"]  "Int" "Int"
     , StreamVertex 2 Filter ["(<15)"] "Int" "Int"
     ]

We can easily manipulate instances of such types, rewrite them, partition them and generate code from them. Unfortunately, this is quite a departure from the first simple code example from the perspective of a user writing their program. Template Haskell gives us the ability to manipulate code as a data structure, and also to inspect names to gather information about them (their type, etc.). I started looking at TH to see if we could build something where the user-supplied program was as close to that first case as possible. TH limitations There are two reasons that we can't easily manipulate a stream-processing definition written as in the first example. The following expressions are equivalent, in some sense, but are not equal, and so yield completely different expression trees when quasi-quoted:

[  streamFilter (<15) . streamFilter (>5) . streamMap (*2)  ]
  \s -> streamFilter (<15) (streamFilter (>5) (streamMap (*2) s))  ]
[  streamMap (*2) >>> streamFilter (>5) >>> streamFilter (<15)  ]
[  \s -> s & streamMap (*2) & streamFilter (>5) & streamFilter (<15)  ]
[  streamFn  ] -- a named expression, defined outside the quasi-quotes

In theory, reify can give you the definition of a function from its name, but in practice it doesn't, because this was never implemented. So at the very least we would need to insist that a user included the entirety of a stream-processing program within quasi-quotes, and not split it up into separate bits, with some bits defined outside the quotes and references within (as in the last case above). We would probably have to insist on a consistent approach for composing operators together, such as always use (.) and never >>>, &, etc. which is limiting. Incremental approach After a while ruminating on this, and before moving onto something else, I thought I'd try approaching it from the other side. Could I introduce some TH into the existing approach, and improve it? The first thing I've tried is to change the parameters field to TH's ExpQ, meaning the map instance example above would be

StreamVertex 0 Map [ [  (*2)  ] ] "Int" "Int"

I worked this through. It's an incremental improvement ease and clarity for the user writing a stream-processing program. It catches a class of programming bugs that would otherwise slip through: the expressions in the brackets have to be syntactically valid (although they aren't type checked). Some of the StrIoT internals are also much improved, particularly the logical operator. Here's an excerpt from a rewrite rule that involves composing code embedded in strings, dealing with all the escaping rules and hoping we've accounted for all possible incoming expression encodings:

let f' = "(let f = ("++f++"); p = ("++p++"); g = ("++g++") in\
         \ \\ (a,b) v -> (f a v, if p v a then g b v else b))"
    a' = "("++a++","++b++")"
    q' = "(let p = ("++p++"); q = ("++q++") in \\v (y,z) -> p v y && q v z)"

And the same section after, manipulating ExpQ types:

let f' = [  \ (a,b) v -> ($(f) a v, if $(p) v a then $(g) b v else b)  ]
    a' = [  ($(a), $(b))  ]
    q' = [  \v (y,z) -> $(p) v y && $(q) v z  ]

I think the code-generation part of StrIoT could be radically refactored to take advantage of this change but I have not made huge inroads into that. Next steps This is, probably, where I am going to stop. This work is very interesting to me but not the main thrust of my research. But incrementally improving the representation gave me some ideas of what I could try next:

intype and outtype could be TH Types instead of Strings. This would catch some simple problems like typos, etc., but we could possibly go further, and
remove the explicit in-and-out-types and infer their values from the parameters field, as its an expression with some type that should match
parameters is a list, because the different stream operators have different arities. streamFilter has one parameter (the filter predicate), so the list should have one element in that case, but streamExpand has none, so it should be empty. We could collapse this to a single ExpQ, which encoded however many parameters are necessary, either in an internal list, or
the operator field could be merged in too, so that the parameters expression was actually a call to the relevant operator with its parameters supplied.

The type would have collapsed down to

data StreamVertex = StreamVertex
      vertexId   :: Int
    , opAndParams :: ExpQ
      deriving (Eq,Show)

Example instances might be

StreamVertex 0 [  streamMap (*2)  ]
StreamVertex 1 [  streamExpand  ]
StreamVertex 2 [  streamScan (\c _ -> c+1) 0  ]

The vertexId field is a bit of wart, but we require that due to the graph data structure that we are using. A change there could eliminate it, too. By this point we are not that far away from where we started, and certainly much closer to the "pure" function application in the very first example.

9 June 2020

Ingo Juergensmann: Jabber vs. XMPP

XMPP is widely - and mabye better - known as Jabber. This was more or less the same until Cisco bought Jabber Inc and the trademark. You can read more about the story on the XMPP.org website. But is there still a Jabber around? Yes, it is! But Cisco Jabber is a whole infrastructure environment: you can't use Cisco Jabber client on its own without the other required Cisco infrastructure as Cisco CUCM and CIsco IM&P servers. So you can't just setup Prosody or ejabberd on your Debian server and connect Cisco Jabber to it. But what are the differences of Cisco Jabber to "standard" XMPP clients? Cisco Jabber

The above screenshot from the official Cisco Jabber product webpage shows the new, single view layout of the Cisco Webex Teams client, but you can configure the client to have the old, classic split view layout of Contact List and Chat Window. But as you can already see from above screenshot audio & video calls is one of the core functions of Cisco Jabber whereas this feature has been added only lately to the well-known Conversations XMPP client on Android. Conversations is using Jingle extension to XMPP whereas Jabber uses SIP for voice/video calls. You can even use Cisco Jabber to control your deskphone via CTI, which is a quite common setup for Jabber. In fact you can configure Jabber to be just a CTI client to you phone or a fully featured UC client. When you don't want to have Ciscos full set of on-premise servers, you can also use Cisco Jabber in conjunction with Cisco Webex as Cisco Webex Messenger. Or in conjunction with Webex Teams in Teams Messaging Mode. Last month Cisco announced general availability of XMPP federation for Webex Teams/Jabber in Teams Messaging Mode. With that you have basic functionality in Webex Teams. And when I say "basic" I really mean basic: you can have 1:1 chat only, no group chats (MUC) and no Presence status will be possible. Hopefully this is just the beginning and not the end of XMPP support in Webex Teams. XMPP Clients

Well, I'm sure many of you know "normal" XMPP clients such as Gajim or Dino on Linux, Conversations on Android or Siskin/Monal/ChatSecure on Apple IOS. There are plenty of other clients of course and maybe you used an XMPP client in the past without knowing it. For example Jitsi Meet is based on XMPP and you can still download the Jitsi Desktop client and use it as a full-featured multi-protocol client, e.g. for XMPP and SIP. In fact Jitsi Desktop is maybe the client that comes closest to Cisco Jabber as a chat/voice/video client. In fact I already connected Jitsi Desktop to Cisco CUCM/IM&P infrastructure, but of course you won't be able to use all those Cisco proprietary extensions, but you can see the benefit of open, standardized protocols such as XMPP and SIP: you are free to use any standard compliant client that you want. So, while Jitsi supported voice/video calls for a long time, even before they focussed on Jitsi Meet as a WebRTC based conference service, Conversations added this feature last month, as already stated. This had a huge effect to the whole XMPP federation, because you need an XMPP server that supports XEP-0215 to make these audio/video calls work. The well-known Compliance Tester listed the STUN/TURN features first as "Informational Tests", but quickly made this a mandatory test to pass tests and gain 100% on the Compliance Tester. But you cannot place SIP calls to other sides, because that's a different thing. As many of you are familiar with standard XMPP clients, I'll focus now on some similarity and differences between Cisco Jabber and standard XMPP... Similarities & Differences First, you can federate with Cisco Jabber users. Cisco IM&P can use standard XMPP federation with all other XMPP standard compliant servers. This is really a big benefit and way better than other solutions that usually results in vendor lock-in. Depending on the setup, you can even join from your own XMPP client in MUCs (Multi User Chats), which Cisco calls "Persistent Chat Room". The other way is not that simple: basically it is possible to join with Cisco Jabber in a MUC on a random server, but it is not as easy as you might thing. Cisco Jabber simply lacks a way to enter a room JID (as you can find them on https://search.jabber.network/. Instead you need to be added as participant by a moderator or an admin in that 3rd party MUC. Managed File Transfers is another issue. Cisco Jabber supports Peer-to-Peer file transfers and Managed File Transfers, where the uploaded file get transferred to an SFTP server as storage backend and where the IM&P server is handling the transfer via HTTPS. You can find a schematic drawing in the Configuration Guides. Although it appears similar to HTTP Upload as defined in XEP-0363, it is not very likely that it will work. I haven't tested it yet, because in my test scenario there is a gatekeeper in the path: Cisco Expressway doesn't support (yet) Managed File Transfer, but you can upvote the idea in the ideas management of Cisco or other ideas such as OMEMO support. OMEMO support? Yes, there is no end-to-end encryption (E2EE) currently planned for Cisco Jabber, while it is common nowadays for most modern XMPP clients. I think it would be good for Cisco Jabber to also (optionally) support OMEMO or its successor. Messaging clients without E2EE are not state of the art anymore. Whereas Conversations is the de-facto standard on Android, Apple IOS devices are still lacking a similar well-working client. See my blog post "XMPP - Fun with Clients" for a summary. In that regard Cisco Jabber might be the best XMPP client for IOS to some degree: you have working messaging, voice/video calls, Push Notifications and integration into Apples Call Kit. There are most likely many, many more differences and issues between Cisco Jabber and standard compliant XMPP servers and clients. But basically Cisco Jabber is still based on XMPP and extends that by proprietary extensions. Summary While I have the impression that the free clients and servers are well doing and increased development in the past years (thanks to Conversations and the Compliance Tester), the situation of Cisco Jabber is a little different. As a customer you can sometimes get the impression that Cisco has lost interest in developing Cisco Jabber. It got better in the last years, but when Cisco Spark was introduced some years ago, the impression was that Cisco is heavily focussed on Spark (now: Webex Teams). It's not like Cisco is not listening to customers or the development has been stopped on Jabber, but my impression is that most customers don't give feedback or tell Cisco as the vendor what they want. You can either submit ideas via the Colaboration Customer Ideas Tool or provide feedback via your Cisco and partner channels. I think it is important for the XMPP community to also have a large enterprise level vendor like Cisco. Otherwise the Internet will become more and more an Internet of closed silos like MS Teams, Slack, Facebook, etc. Of course there are other companies like ProcessOne (ejabberd) or Tigase, but I think you agree that Cisco is another level.

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