More from Tyler Cipriani: blog
Any code of your own that you haven’t looked at for six or more months might as well have been written by someone else. – Eagleson’s Law After scouring git history, I found the correct config file, but someone removed it. Their full commit message read: Remove config. Don't bring it back. Very. helpful. But I get it; it’s hard to care about commit messages when you’re making a quick change. Git commit templates can help. Commit templates provide a scaffold for your commit messages, reminding you to answer questions like: What problem are you solving? Why is this the solution? What alternatives did you consider? Where can I read more? What is a git commit template? When you type git commit, git pops open your text editor1. Git can pre-fill your editor with a commit template—a form that reminds you of everything it’s easy to forget when writing a commit. Creating a commit template is simple. Create a plaintext file – mine lives at ~/.config/git/message.txt Tell git to use it: git config --global \ commit.template '~/.config/git/message.txt' My template packs everything I know about writing a commit. Project-specific templates Large projects, such as Linux kernel, git, and MediaWiki, have their own commit guidelines. Git templates can remind you about these per-project requirements if you add a commit template to a project’s .git/config file. Another way to do this is git’s includeIf configuration setting. includeIf lets you override git config settings when you’re working under directories you define. For example, all my Wikimedia work lives in ~/Projects/Wikimedia and at the bottom of my ~/.config/git/config I have: [includeIf "gitdir:~/Projects/Wikimedia/**"] path = ~/.config/git/config.wikimedia In config.wikimedia, I point to my Wikimedia-specific commit template (along with other necessary git settings: my user.email, core.hooksPath, and a pushInsteadOf url to push to ssh even when I clone via https). Forge-specific templates Personal git commit templates lead to better commits, which make for a better history. The forge-specific pull-request templates are a band-aid, the cheap kind that falls off in the shower. There’s no incentive for GitHub to make git history better: the worse your commit history, the more you rely on GitHub. Still, all the major pull-request-style forges let you foist a pull-request template on your contributors. As a contributor, I dislike filling those out—they add unnecessary friction. Commit message contents Your commit template allows you do the hard thinking upfront. Then, when you make a commit, you simply follow the template. My template asks questions I answer with my commit message: 72ch. wide -------------------------------------------------------- BODY # | # - Why should this change be made? | # - What problem are you solving? | # - Why this solution? | # - What's wrong with the current code? | # - Are there other ways to do it? | # - How can the reviewer confirm it works? | # | # ---------------------------------------------------------------- /BODY But other clever folks cooked up conventions you could incorporate: Conventional commits – how do your commits relate to semantic versioning? This makes it easier for SRE and downstream users. Problem/Solution format – first pioneered by ZeroMQ2, this format anticipates the questions of future developers and reviewers. Gitmoji – developed for the GitHub crowd, this format defines an emoji shorthand that makes it easy to spot changes of a particular type. Commit message formatting How you format text affects how people read it. My template also deals with text formatting rules3: Subject – 50 characters or less, capitalized, no end punctuation. Body – Wrap at 72 characters with a blank line separating it from the subject. Trailers – Standard formats with a blank line separating them from the body. People will read your commit in different contexts: git log, git shortlog, and git rebase. But git’s pager has no line wrapping by default. I hard wrap at 72 characters because that makes text easier to read in wide terminals.4 Finally, my template addresses trailers, reminding me about standard trailers supported in the projects I’m working on. Git can interpret trailers, which can be useful later. For example, if I wanted a tab-separated list of commits and their related tasks I could find that with git log: $ TAB=%x09 $ BUG_TRAILER='%(trailers:key=Bug,valueonly=true,separator=%x2C )' $ SHORT_HASH=%h $ SUBJ=%s $ FORMAT="${SHORT_HASH}${TAB}${BUG_TRAILER}${TAB}${GIT_SUBJ}" $ git log --topo-order --no-merges \ --format="$FORMAT" d2b09deb12f T359762 Rewrite Kurdish (ku) Latin to Arabic converter 28123a6a262 T332865 tests: Remove non-static fallback in HookRunnerTestBase 4e919a307a4 T328919 tests: Remove unused argument from data provider in PageUpdaterTest bedd0f685f9 objectcache: Improve `RESTBagOStuff::handleError()` 2182a0c4490 T393219 tests: Remove two data provider in RestStructureTest Git commit templates free your brain from remembering what you should write, allowing you to focus on the story you should tell. Your future self will thank you for the effort. Starting with core.editor in your git config, $VISUAL or $EDITOR in your shell, finally falling back to vi.↩︎ I think…↩︎ All cribbed from Tim Pope↩︎ Another story I’ve heard: a standard terminal allows 80 characters per line. git log indents commit messages with 4 spaces. A 72-character-per-line commit centers text on an 80-character-per-line terminal. To me, readability in modern terminals is a better reason to wrap than kowtowing to antiquated terminals.↩︎
[The] Linux kernel uses GPLv2, and if you distribute GPLv2 code, you have to provide a copy of the source (and modifications) once someone asks for it. And now I’m asking nicely for you to do so 🙂 – Joga, bbs.onyx-international.com Boox in split screen, typewriter mode In January, I bought a Boox Go 10.3—a 10.3-inch, 300-ppi, e-ink Android tablet. After two months, I use the Boox daily—it’s replaced my planner, notebook, countless PDF print-offs, and the good parts of my phone. But Boox’s parent company, Onyx, is sketchy. I’m conflicted. The Boox Go is a beautiful, capable tablet that I use every day, but I recommend avoiding as long as Onyx continues to disregard the rights of its users. How I’m using my Boox My e-ink floor desk Each morning, I plop down in front of my MagicHold laptop stand and journal on my Boox with Obsidian. I use Syncthing to back up my planner and sync my Zotero library between my Boox and laptop. In the evening, I review my PDF planner and plot for tomorrow. I use these apps: Obsidian – a markdown editor that syncs between all my devices with no fuss for $8/mo. Syncthing – I love Syncthing—it’s an encrypted, continuous file sync-er without a centralized server. Meditation apps1 – Guided meditation away from the blue light glow of my phone or computer is better. Before buying the Boox, I considered a reMarkable. The reMarkable Paper Pro has a beautiful color screen with a frontlight, a nice pen, and a “type folio,” plus it’s certified by the Calm Tech Institute. But the reMarkable is a distraction-free e-ink tablet. Meanwhile, I need distraction-lite. What I like Calm(ish) technology – The Boox is an intentional device. Browsing the internet, reading emails, and watching videos is hard, but that’s good. Apps – Google Play works out of the box. I can install F-Droid and change my launcher without difficulty. Split screen – The built-in launcher has a split screen feature. I use it to open a PDF side-by-side with a notes doc. Reading – The screen is a 300ppi Carta 1200, making text crisp and clear. What I dislike I filmed myself typing at 240fps, each frame is 4.17ms. Boox’s typing latency is between 150ms and 275ms at the fastest refresh rate inside Obsidian. Typing – Typing latency is noticeable. At Boox’s highest refresh rate, after hitting a key, text takes between 150ms to 275ms to appear. I can still type, though it’s distracting at times. The horror of the default pen Accessories Pen – The default pen looks like a child’s whiteboard marker and feels cheap. I replaced it with the Kindle Scribe Premium pen, and the writing experience is vastly improved. Cover – It’s impossible to find a nice cover. I’m using a $15 cover that I’m encasing in stickers. Tool switching – Swapping between apps is slow and clunky. I blame Android and the current limitations of e-ink more than Boox. No frontlight – The Boox’s lack of frontlight prevents me from reading more with it. I knew this when I bought my Boox, but devices with frontlights seem to make other compromises. Onyx The Chinese company behind Boox, Onyx International, Inc., runs the servers where Boox shuttles tracking information. I block this traffic with Pi-Hole2. pihole-ing whatever telemetry Boox collects I inspected this traffic via Mitm proxy—most traffic was benign, though I never opted into sending any telemetry (nor am I logged in to a Boox account). But it’s also an Android device, so it’s feeding telemetry into Google’s gaping maw, too. Worse, Onyx is flouting the terms of the GNU Public License, declining to release Linux kernel modifications to users. This is anathema to me—GPL violations are tantamount to theft. Onyx’s disregard for user rights makes me regret buying the Boox. Verdict I’ll continue to use the Boox and feel bad about it. I hope my digging in this post will help the next person. Unfortunately, the e-ink tablet market is too niche to support the kind of solarpunk future I’d always imagined. But there’s an opportunity for an open, Linux-based tablet to dominate e-ink. Linux is playing catch-up on phones with PostmarketOS. Meanwhile, the best e-ink tablets have to offer are old, unupdateable versions of Android, like the OS on the Boox. In the future, I’d love to pay a license- and privacy-respecting company for beautiful, calm technology and recommend their product to everyone. But today is not the future. I go back and forth between “Waking Up” and “Calm”↩︎ Using github.com/JordanEJ/Onyx-Boox-Blocklist↩︎
.title { text-wrap: balance } Spending for October, generated by piping hledger → R Over the past six months, I’ve tracked my money with hledger—a plain text double-entry accounting system written in Haskell. It’s been surprisingly painless. My previous attempts to pick up real accounting tools floundered. Hosted tools are privacy nightmares, and my stint with GnuCash didn’t last. But after stumbling on Dmitry Astapov’s “Full-fledged hledger” wiki1, it clicked—eventually consistent accounting. Instead of modeling your money all at once, take it one hacking session at a time. It should be easy to work towards eventual consistency. […] I should be able to [add financial records] bit by little bit, leaving things half-done, and picking them up later with little (mental) effort. – Dmitry Astapov, Full-Fledged Hledger Principles of my system I’ve cobbled together a system based on these principles: Avoid manual entry – Avoid typing in each transaction. Instead, rely on CSVs from the bank. CSVs as truth – CSVs are the only things that matter. Everything else can be blown away and rebuilt anytime. Embrace version control – Keep everything under version control in Git for easy comparison and safe experimentation. Learn hledger in five minutes hledger concepts are heady, but its use is simple. I divide the core concepts into two categories: Stuff hledger cares about: Transactions – how hledger moves money between accounts. Journal files – files full of transactions Stuff I care about: Rules files – how I set up accounts, import CSVs, and move money between accounts. Reports – help me see where my money is going and if I messed up my rules. Transactions move money between accounts: 2024-01-01 Payday income:work $-100.00 assets:checking $100.00 This transaction shows that on Jan 1, 2024, money moved from income:work into assets:checking—Payday. The sum of each transaction should be $0. Money comes from somewhere, and the same amount goes somewhere else—double-entry accounting. This is powerful technology—it makes mistakes impossible to ignore. Journal files are text files containing one or more transactions: 2024-01-01 Payday income:work $-100.00 assets:checking $100.00 2024-01-02 QUANSHENG UVK5 assets:checking $-29.34 expenses:fun:radio $29.34 Rules files transform CSVs into journal files via regex matching. Here’s a CSV from my bank: Transaction Date,Description,Category,Type,Amount,Memo 09/01/2024,DEPOSIT Paycheck,Payment,Payment,1000.00, 09/04/2024,PizzaPals Pizza,Food & Drink,Sale,-42.31, 09/03/2024,Amazon.com*XXXXXXXXY,Shopping,Sale,-35.56, 09/03/2024,OBSIDIAN.MD,Shopping,Sale,-10.00, 09/02/2024,Amazon web services,Personal,Sale,-17.89, And here’s a checking.rules to transform that CSV into a journal file so I can use it with hledger: # checking.rules # -------------- # Map CSV fields → hledger fields[0] fields date,description,category,type,amount,memo,_ # `account1`: the account for the whole CSV.[1] account1 assets:checking account2 expenses:unknown skip 1 date-format %m/%d/%Y currency $ if %type Payment account2 income:unknown if %category Food & Drink account2 expenses:food:dining # [0]: <https://hledger.org/hledger.html#field-names> # [1]: <https://hledger.org/hledger.html#account-field> With these two files (checking.rules and 2024-09_checking.csv), I can make the CSV into a journal: $ > 2024-09_checking.journal \ hledger print \ --rules-file checking.rules \ -f 2024-09_checking.csv $ head 2024-09_checking.journal 2024-09-01 DEPOSIT Paycheck assets:checking $1000.00 income:unknown $-1000.00 2024-09-02 Amazon web services assets:checking $-17.89 expenses:unknown $17.89 Reports are interesting ways to view transactions between accounts. There are registers, balance sheets, and income statements: $ hledger incomestatement \ --depth=2 \ --file=2024-09_bank.journal Revenues: $1000.00 income:unknown ----------------------- $1000.00 Expenses: $42.31 expenses:food $63.45 expenses:unknown ----------------------- $105.76 ----------------------- Net: $894.24 At the beginning of September, I spent $105.76 and made $1000, leaving me with $894.24. But a good chunk is going to the default expense account, expenses:unknown. I can use the hleger aregister to see what those transactions are: $ hledger areg expenses:unknown \ --file=2024-09_checking.journal \ -O csv | \ csvcut -c description,change | \ csvlook | description | change | | ------------------------ | ------ | | OBSIDIAN.MD | 10.00 | | Amazon web services | 17.89 | | Amazon.com*XXXXXXXXY | 35.56 | l Then, I can add some more rules to my checking.rules: if OBSIDIAN.MD account2 expenses:personal:subscriptions if Amazon web services account2 expenses:personal:web:hosting if Amazon.com account2 expenses:personal:shopping:amazon Now, I can reprocess my data to get a better picture of my spending: $ > 2024-09_bank.journal \ hledger print \ --rules-file bank.rules \ -f 2024-09_bank.csv $ hledger bal expenses \ --depth=3 \ --percent \ -f 2024-09_checking2.journal 30.0 % expenses:food:dining 33.6 % expenses:personal:shopping 9.5 % expenses:personal:subscriptions 16.9 % expenses:personal:web -------------------- 100.0 % For the Amazon.com purchase, I lumped it into the expenses:personal:shopping account. But I could dig deeper—download my order history from Amazon and categorize that spending. This is the power of working bit-by-bit—the data guides you to the next, deeper rabbit hole. Goals and non-goals Why am I doing this? For years, I maintained a monthly spreadsheet of account balances. I had a balance sheet. But I still had questions. Spending over six months, generated by piping hledger → gnuplot Before diving into accounting software, these were my goals: Granular understanding of my spending – The big one. This is where my monthly spreadsheet fell short. I knew I had money in the bank—I kept my monthly balance sheet. I budgeted up-front the % of my income I was saving. But I had no idea where my other money was going. Data privacy – I’m unwilling to hand the keys to my accounts to YNAB or Mint. Increased value over time – The more time I put in, the more value I want to get out—this is what you get from professional tools built for nerds. While I wished for low-effort setup, I wanted the tool to be able to grow to more uses over time. Non-goals—these are the parts I never cared about: Investment tracking – For now, I left this out of scope. Between monthly balances in my spreadsheet and online investing tools’ ability to drill down, I was fine.2 Taxes – Folks smarter than me help me understand my yearly taxes.3 Shared system – I may want to share reports from this system, but no one will have to work in it except me. Cash – Cash transactions are unimportant to me. I withdraw money from the ATM sometimes. It evaporates. hledger can track all these things. My setup is flexible enough to support them someday. But that’s unimportant to me right now. Monthly maintenance I spend about an hour a month checking in on my money Which frees me to spend time making fancy charts—an activity I perversely enjoy. Income vs. Expense, generated by piping hledger → gnuplot Here’s my setup: $ tree ~/Documents/ledger . ├── export │ ├── 2024-balance-sheet.txt │ └── 2024-income-statement.txt ├── import │ ├── in │ │ ├── amazon │ │ │ └── order-history.csv │ │ ├── credit │ │ │ ├── 2024-01-01_2024-02-01.csv │ │ │ ├── ... │ │ │ └── 2024-10-01_2024-11-01.csv │ │ └── debit │ │ ├── 2024-01-01_2024-02-01.csv │ │ ├── ... │ │ └── 2024-10-01_2024-11-01.csv │ └── journal │ ├── amazon │ │ └── order-history.journal │ ├── credit │ │ ├── 2024-01-01_2024-02-01.journal │ │ ├── ... │ │ └── 2024-10-01_2024-11-01.journal │ └── debit │ ├── 2024-01-01_2024-02-01.journal │ ├── ... │ └── 2024-10-01_2024-11-01.journal ├── rules │ ├── amazon │ │ └── journal.rules │ ├── credit │ │ └── journal.rules │ ├── debit │ │ └── journal.rules │ └── common.rules ├── 2024.journal ├── Makefile └── README Process: Import – download a CSV for the month from each account and plop it into import/in/<account>/<dates>.csv Make – run make Squint – Look at git diff; if it looks good, git add . && git commit -m "💸" otherwise review hledger areg to see details. The Makefile generates everything under import/journal: journal files from my CSVs using their corresponding rules. reports in the export folder I include all the journal files in the 2024.journal with the line: include ./import/journal/*/*.journal Here’s the Makefile: SHELL := /bin/bash RAW_CSV = $(wildcard import/in/**/*.csv) JOURNALS = $(foreach file,$(RAW_CSV),$(subst /in/,/journal/,$(patsubst %.csv,%.journal,$(file)))) .PHONY: all all: $(JOURNALS) hledger is -f 2024.journal > export/2024-income-statement.txt hledger bs -f 2024.journal > export/2024-balance-sheet.txt .PHONY clean clean: rm -rf import/journal/**/*.journal import/journal/%.journal: import/in/%.csv @echo "Processing csv $< to $@" @echo "---" @mkdir -p $(shell dirname $@) @hledger print --rules-file rules/$(shell basename $$(dirname $<))/journal.rules -f "$<" > "$@" If I find anything amiss (e.g., if my balances are different than what the bank tells me), I look at hleger areg. I may tweak my rules or my CSVs and then I run make clean && make and try again. Simple, plain text accounting made simple. And if I ever want to dig deeper, hledger’s docs have more to teach. But for now, the balance of effort vs. reward is perfect. while reading a blog post from Jonathan Dowland↩︎ Note, this is covered by full-fledged hledger – Investements↩︎ Also covered in full-fledged hledger – Tax returns↩︎
Luckily, I speak Leet. – Amita Ramanujan, Numb3rs, CBS’s IRC Drama There’s an episode of the CBS prime-time drama Numb3rs that plumbs the depths of Dr. Joel Fleischman’s1 knowledge of IRC. In one scene, Fleischman wonders, “What’s ‘leet’”? “Leet” is writing that replaces letters with numbers, e.g., “Numb3rs,” where 3 stands in for e. In short, leet is like the heavy-metal “S” you drew in middle school: Sweeeeet. / \ / | \ | | | \ \ | | | \ | / \ / ASCII art version of your misspent youth. Following years of keen observation, I’ve noticed Git commit hashes are also letters and numbers. Git commit hashes are, as Fleischman might say, prime targets for l33tification. What can I spell with a git commit? DenITDao via orlybooks) With hexidecimal we can spell any word containing the set of letters {A, B, C, D, E, F}—DEADBEEF (a classic) or ABBABABE (for Mama Mia aficionados). This is because hexidecimal is a base-16 numbering system—a single “digit” represents 16 numbers: Base-10: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 16 15 Base-16: 0 1 2 3 4 5 6 7 8 9 A B C D E F Leet expands our palette of words—using 0, 1, and 5 to represent O, I, and S, respectively. I created a script that scours a few word lists for valid words and phrases. With it, I found masterpieces like DADB0D (dad bod), BADA55 (bad ass), and 5ADBAB1E5 (sad babies). Manipulating commit hashes for fun and no profit Git commit hashes are no mystery. A commit hash is the SHA-1 of a commit object. And a commit object is the commit message with some metadata. $ mkdir /tmp/BADA55-git && cd /tmp/BAD55-git $ git init Initialized empty Git repository in /tmp/BADA55-git/.git/ $ echo '# BADA55 git repo' > README.md && git add README.md && git commit -m 'Initial commit' [main (root-commit) 68ec0dd] Initial commit 1 file changed, 1 insertion(+) create mode 100644 README.md $ git log --oneline 68ec0dd (HEAD -> main) Initial commit Let’s confirm we can recreate the commit hash: $ git cat-file -p 68ec0dd > commit-msg $ sha1sum <(cat \ <(printf "commit ") \ <(wc -c < commit-msg | tr -d '\n') \ <(printf '%b' '\0') commit-msg) 68ec0dd6dead532f18082b72beeb73bd828ee8fc /dev/fd/63 Our repo’s first commit has the hash 68ec0dd. My goal is: Make 68ec0dd be BADA55. Keep the commit message the same, visibly at least. But I’ll need to change the commit to change the hash. To keep those changes invisible in the output of git log, I’ll add a \t and see what happens to the hash. $ truncate -s -1 commit-msg # remove final newline $ printf '\t\n' >> commit-msg # Add a tab $ # Check the new SHA to see if it's BADA55 $ sha1sum <(cat \ <(printf "commit ") \ <(wc -c < commit-msg | tr -d '\n') \ <(printf '%b' '\0') commit-msg) 27b22ba5e1c837a34329891c15408208a944aa24 /dev/fd/63 Success! I changed the SHA-1. Now to do this until we get to BADA55. Fortunately, user not-an-aardvark created a tool for that—lucky-commit that manipulates a commit message, adding a combination of \t and [:space:] characters until you hit a desired SHA-1. Written in rust, lucky-commit computes all 256 unique 8-bit strings composed of only tabs and spaces. And then pads out commits up to 48-bits with those strings, using worker threads to quickly compute the SHA-12 of each commit. It’s pretty fast: $ time lucky_commit BADA555 real 0m0.091s user 0m0.653s sys 0m0.007s $ git log --oneline bada555 (HEAD -> main) Initial commit $ xxd -c1 <(git cat-file -p 68ec0dd) | grep -cPo ': (20|09)' 12 $ xxd -c1 <(git cat-file -p HEAD) | grep -cPo ': (20|09)' 111 Now we have an more than an initial commit. We have a BADA555 initial commit. All that’s left to do is to make ALL our commits BADA55 by abusing git hooks. $ cat > .git/hooks/post-commit && chmod +x .git/hooks/post-commit #!/usr/bin/env bash echo 'L337-ifying!' lucky_commit BADA55 $ echo 'A repo that is very l33t.' >> README.md && git commit -a -m 'l33t' L337-ifying! [main 0e00cb2] l33t 1 file changed, 1 insertion(+) $ git log --oneline bada552 (HEAD -> main) l33t bada555 Initial commit And now I have a git repo almost as cool as the sweet “S” I drew in middle school. This is a Northern Exposure spin off, right? I’ve only seen 1:48 of the show…↩︎ or SHA-256 for repos that have made the jump to a more secure hash function↩︎
A brief and biased history. Oh yeah, there’s pull requests now – GitHub blog, Sat, 23 Feb 2008 When GitHub launched, it had no code review. Three years after launch, in 2011, GitHub user rtomayko became the first person to make a real code comment, which read, in full: “+1”. Before that, GitHub lacked any way to comment on code directly. Instead, pull requests were a combination of two simple features: Cross repository compare view – a feature they’d debuted in 2010—git diff in a web page. A comments section – a feature most blogs had in the 90s. There was no way to thread comments, and the comments were on a different page than the diff. GitHub pull requests circa 2010. This is from the official documentation on GitHub. Earlier still, when the pull request debuted, GitHub claimed only that pull requests were “a way to poke someone about code”—a way to direct message maintainers, but one that lacked any web view of the code whatsoever. For developers, it worked like this: Make a fork. Click “pull request”. Write a message in a text form. Send the message to someone1 with a link to your fork. Wait for them to reply. In effect, pull requests were a limited way to send emails to other GitHub users. Ten years after this humble beginning—seven years after the first code comment—when Microsoft acquired GitHub for $7.5 Billion, this cobbled-together system known as “GitHub flow” had become the default way to collaborate on code via Git. And I hate it. Pull requests were never designed. They emerged. But not from careful consideration of the needs of developers or maintainers. Pull requests work like they do because they were easy to build. In 2008, GitHub’s developers could have opted to use git format-patch instead of teaching the world to juggle branches. Or they might have chosen to generate pull requests using the git request-pull command that’s existed in Git since 2005 and is still used by the Linux kernel maintainers today2. Instead, they shrugged into GitHub flow, and that flow taught the world to use Git. And commit histories have sucked ever since. For some reason, github has attracted people who have zero taste, don’t care about commit logs, and can’t be bothered. – Linus Torvalds, 2012 “Someone” was a person chosen by you from a checklist of the people who had also forked this repository at some point.↩︎ Though to make small, contained changes you’d use git format-patch and git am.↩︎
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Here are a few tangentially-related ideas vaguely near the theme of comparison operators. comparison style clamp style clamp is median clamp in range range style style clash? comparison style Some languages such as BCPL, Icon, Python have chained comparison operators, like if min <= x <= max: ... In languages without chained comparison, I like to write comparisons as if they were chained, like, if min <= x && x <= max { // ... } A rule of thumb is to prefer less than (or equal) operators and avoid greater than. In a sequence of comparisons, order values from (expected) least to greatest. clamp style The clamp() function ensures a value is between some min and max, def clamp(min, x, max): if x < min: return min if max < x: return max return x I like to order its arguments matching the expected order of the values, following my rule of thumb for comparisons. (I used that flavour of clamp() in my article about GCRA.) But I seem to be unusual in this preference, based on a few examples I have seen recently. clamp is median Last month, Fabian Giesen pointed out a way to resolve this difference of opinion: A function that returns the median of three values is equivalent to a clamp() function that doesn’t care about the order of its arguments. This version is written so that it returns NaN if any of its arguments is NaN. (When an argument is NaN, both of its comparisons will be false.) fn med3(a: f64, b: f64, c: f64) -> f64 { match (a <= b, b <= c, c <= a) { (false, false, false) => f64::NAN, (false, false, true) => b, // a > b > c (false, true, false) => a, // c > a > b (false, true, true) => c, // b <= c <= a (true, false, false) => c, // b > c > a (true, false, true) => a, // c <= a <= b (true, true, false) => b, // a <= b <= c (true, true, true) => b, // a == b == c } } When two of its arguments are constant, med3() should compile to the same code as a simple clamp(); but med3()’s misuse-resistance comes at a small cost when the arguments are not known at compile time. clamp in range If your language has proper range types, there is a nicer way to make clamp() resistant to misuse: fn clamp(x: f64, r: RangeInclusive<f64>) -> f64 { let (&min,&max) = (r.start(), r.end()); if x < min { return min } if max < x { return max } return x; } let x = clamp(x, MIN..=MAX); range style For a long time I have been fond of the idea of a simple counting for loop that matches the syntax of chained comparisons, like for min <= x <= max: ... By itself this is silly: too cute and too ad-hoc. I’m also dissatisfied with the range or slice syntax in basically every programming language I’ve seen. I thought it might be nice if the cute comparison and iteration syntaxes were aspects of a more generally useful range syntax, but I couldn’t make it work. Until recently when I realised I could make use of prefix or mixfix syntax, instead of confining myself to infix. So now my fantasy pet range syntax looks like >= min < max // half-open >= min <= max // inclusive And you might use it in a pattern match if x is >= min < max { // ... } Or as an iterator for x in >= min < max { // ... } Or to take a slice xs[>= min < max] style clash? It’s kind of ironic that these range examples don’t follow the left-to-right, lesser-to-greater rule of thumb that this post started off with. (x is not lexically between min and max!) But that rule of thumb is really intended for languages such as C that don’t have ranges. Careful stylistic conventions can help to avoid mistakes in nontrivial conditional expressions. It’s much better if language and library features reduce the need for nontrivial conditions and catch mistakes automatically.
Email is your most important online account, so keep it clean.
Kubernetes is not exactly the most fun piece of technology around. Learning it isn’t easy, and learning the surrounding ecosystem is even harder. Even those who have managed to tame it are still afraid of getting paged by an ETCD cluster corruption, a Kubelet certificate expiration, or the DNS breaking down (and somehow, it’s always the DNS). Samuel Sianipar If you’re like me, the thought of making your own orchestrator has crossed your mind a few times. The result would, of course, be a magical piece of technology that is both simple to learn and wouldn’t break down every weekend. Sadly, the task seems daunting. Kubernetes is a multi-million lines of code project which has been worked on for more than a decade. The good thing is someone wrote a book that can serve as a good starting point to explore the idea of building our own container orchestrator. This book is named “Build an Orchestrator in Go”, written by Tim Boring, published by Manning. The tasks The basic unit of our container orchestrator is called a “task”. A task represents a single container. It contains configuration data, like the container’s name, image and exposed ports. Most importantly, it indicates the container state, and so acts as a state machine. The state of a task can be Pending, Scheduled, Running, Completed or Failed. Each task will need to interact with a container runtime, through a client. In the book, we use Docker (aka Moby). The client will get its configuration from the task and then proceed to pull the image, create the container and start it. When it is time to finish the task, it will stop the container and remove it. The workers Above the task, we have workers. Each machine in the cluster runs a worker. Workers expose an API through which they receive commands. Those commands are added to a queue to be processed asynchronously. When the queue gets processed, the worker will start or stop tasks using the container client. In addition to exposing the ability to start and stop tasks, the worker must be able to list all the tasks running on it. This demands keeping a task database in the worker’s memory and updating it every time a task change’s state. The worker also needs to be able to provide information about its resources, like the available CPU and memory. The book suggests reading the /proc Linux file system using goprocinfo, but since I use a Mac, I used gopsutil. The manager On top of our cluster of workers, we have the manager. The manager also exposes an API, which allows us to start, stop, and list tasks on the cluster. Every time we want to create a new task, the manager will call a scheduler component. The scheduler has to list the workers that can accept more tasks, assign them a score by suitability and return the best one. When this is done, the manager will send the work to be done using the worker’s API. In the book, the author also suggests that the manager component should keep track of every tasks state by performing regular health checks. Health checks typically consist of querying an HTTP endpoint (i.e. /ready) and checking if it returns 200. In case a health check fails, the manager asks the worker to restart the task. I’m not sure if I agree with this idea. This could lead to the manager and worker having differing opinions about a task state. It will also cause scaling issues: the manager workload will have to grow linearly as we add tasks, and not just when we add workers. As far as I know, in Kubernetes, Kubelet (the equivalent of the worker here) is responsible for performing health checks. The CLI The last part of the project is to create a CLI to make sure our new orchestrator can be used without having to resort to firing up curl. The CLI needs to implement the following features: start a worker start a manager run a task in the cluster stop a task get the task status get the worker node status Using cobra makes this part fairly straightforward. It lets you create very modern feeling command-line apps, with properly formatted help commands and easy argument parsing. Once this is done, we almost have a fully functional orchestrator. We just need to add authentication. And maybe some kind of DaemonSet implementation would be nice. And a way to handle mounting volumes…
Unexamined life is not worth living said Socrates. I don’t know about that but to become a better, faster, more productive programmer it pays to examine what makes you un-productive. Fixing bugs is one of those un-productive activities. You have to fix them but it would be even better if you didn’t write them in the first place. Therefore it’s good to reflect after fixing a bug. Why did the bug happen? Could I have done something to not write the bug in the first place? If I did write the bug, could I do something to diagnose or fix it faster? This seems like a great idea that I wasn’t doing. Until now. Here’s a random selection of bugs I found and fixed in SumatraPDF, with some reflections. SumatraPDF is a C++ win32 Windows app. It’s a small, fast, open-source, multi-format PDF/eBook/Comic Book reader. To keep the app small and fast I generally avoid using other people’s code. As a result most code is mine and most bugs are mine. Let’s reflect on those bugs. TabWidth doesn’t work A user reported that TabWidth advanced setting doesn’t work in 3.5.2 but worked in 3.4.6. I looked at the code and indeed: the setting was not used anywhere. The fix was to use it. Why did the bug happen? It was a refactoring. I heavily refactored tabs control. Somehow during the rewrite I forgot to use the advanced setting when creating the new tabs control, even though I did write the code to support it in the control. I guess you could call it sloppiness. How could I not write the bug? I could review the changes more carefully. There’s no-one else working on this project so there’s no one else to do additional code reviews. I typically do a code review by myself with webdiff but let’s face it: reviewing changes right after writing them is the worst possible time. I’m biased to think that the code I just wrote is correct and I’m often mentally exhausted. Maybe I should adopt a process when I review changes made yesterday with fresh, un-tired eyes? How could I detect the bug earlier?. 3.5.2 release happened over a year ago. Could I have found it sooner? I knew I was refactoring tabs code. I knew I have a setting for changing the look of tabs. If I connected the dots at the time, I could have tested if the setting still works. I don’t make releases too often. I could do more testing before each release and at the very least verify all advanced settings work as expected. The real problem In retrospect, I shouldn’t have implemented that feature at all. I like Sumatra’s customizability and I think it’s non-trivial contributor to it’s popularity but it took over a year for someone to notice and report that particular bug. It’s clear it’s not a frequently used feature. I implemented it because someone asked and it was easy. I should have said no to that particular request. Fix printing crash by correctly ref-counting engine Bugs can crash your program. Users rarely report crashes even though I did put effort into making it easy. When I a crash happens I have a crash handler that saves the diagnostic info to a file and I show a message box asking users to report the crash and with a press of a button I launch a notepad with diagnostic info and a browser with a page describing how to submit that as a GitHub issue. The other button is to ignore my pleas for help. Most users overwhelmingly choose to ignore. I know that because I also have crash reporting system that sends me a crash report. I get thousands of crash reports for every crash reported by the user. Therefore I’m convinced that the single most impactful thing for making software that doesn’t crash is to have a crash reporting system, look at the crashes and fix them. This is not a perfect system because all I have is a call stack of crashed thread, info about the computer and very limited logs. Nevertheless, sometimes all it takes is a look at the crash call stack and inspection of the code. I saw a crash in printing code which I fixed after some code inspection. The clue was that I was accessing a seemingly destroyed instance of Engine. That was easy to diagnose because I just refactored the code to add ref-counting to Engine so it was easy to connect the dots. I’m not a fan of ref-counting. It’s easy to mess up ref-counting (add too many refs, which leads to memory leaks or too many releases which leads to premature destruction). I’ve seen codebases where developers were crazy in love with ref-counting: every little thing, even objects with obvious lifetimes. In contrast,, that was the first ref-counted object in over 100k loc of SumatraPDF code. It was necessary in this case because I would potentially hand off the object to a printing thread so its lifetime could outlast the lifetime of the window for which it was created. How could I not write the bug? It’s another case of sloppiness but I don’t feel bad. I think the bug existed there before the refactoring and this is the hard part about programming: complex interactions between distant, in space and time, parts of the program. Again, more time spent reviewing the change could have prevented it. As a bonus, I managed to simplify the logic a bit. Writing software is an incremental process. I could feel bad about not writing the perfect code from the beginning but I choose to enjoy the process of finding and implementing improvements. Making the code and the program better over time. Tracking down a chm thumbnail crash Not all crashes can be fixed given information in crash report. I saw a report with crash related to creating a thumbnail crash. I couldn’t figure out why it crashes but I could add more logging to help figure out the issue if it happens again. If it doesn’t happen again, then I win. If it does happen again, I will have more context in the log to help me figure out the issue. Update: I did fix the crash. Fix crash when viewing favorites menu A user reported a crash. I was able to reproduce the crash and fix it. This is the bast case scenario: a bug report with instructions to reproduce a crash. If I can reproduce the crash when running debug build under the debugger, it’s typically very easy to figure out the problem and fix it. In this case I’ve recently implemented an improved version of StrVec (vector of strings) class. It had a compatibility bug compared to previous implementation in that StrVec::InsertAt(0) into an empty vector would crash. Arguably it’s not a correct usage but existing code used it so I’ve added support to InsertAt() at the end of vector. How could I not write the bug? I should have written a unit test (which I did in the fix). I don’t blindly advocate unit tests. Writing tests has a productivity cost but for such low-level, relatively tricky code, unit tests are good. I don’t feel too bad about it. I did write lots of tests for StrVec and arguably this particular usage of InsertAt() was borderline correct so it didn’t occur to me to test that condition. Use after free I saw a crash in crash reports, close to DeleteThumbnailForFile(). I looked at the code: if (!fs->favorites->IsEmpty()) { // only hide documents with favorites gFileHistory.MarkFileInexistent(fs->filePath, true); } else { gFileHistory.Remove(fs); DeleteDisplayState(fs); } DeleteThumbnailForFile(fs->filePath); I immediately spotted suspicious part: we call DeleteDisplayState(fs) and then might use fs->filePath. I looked at DeleteDisplayState and it does, in fact, deletes fs and all its data, including filePath. So we use freed data in a classic use after free bug. The fix was simple: make a copy of fs->filePath before calling DeleteDisplayState and use that. How could I not write the bug? Same story: be more careful when reviewing the changes, test the changes more. If I fail that, crash reporting saves my ass. The bug didn’t last more than a few days and affected only one user. I immediately fixed it and published an update. Summary of being more productive and writing bug free software If many people use your software, a crash reporting system is a must. Crashes happen and few of them are reported by users. Code reviews can catch bugs but they are also costly and reviewing your own code right after you write it is not a good time. You’re tired and biased to think your code is correct. Maybe reviewing the code a day after, with fresh eyes, would be better. I don’t know, I haven’t tried it.
A little while back I heard about the White House launching their version of a Drudge Report style website called White House Wire. According to Axios, a White House official said the site’s purpose was to serve as “a place for supporters of the president’s agenda to get the real news all in one place”. So a link blog, if you will. As a self-professed connoisseur of websites and link blogs, this got me thinking: “I wonder what kind of links they’re considering as ‘real news’ and what they’re linking to?” So I decided to do quick analysis using Quadratic, a programmable spreadsheet where you can write code and return values to a 2d interface of rows and columns. I wrote some JavaScript to: Fetch the HTML page at whitehouse.gov/wire Parse it with cheerio Select all the external links on the page Return a list of links and their headline text In a few minutes I had a quick analysis of what kind of links were on the page: This immediately sparked my curiosity to know more about the meta information around the links, like: If you grouped all the links together, which sites get linked to the most? What kind of interesting data could you pull from the headlines they’re writing, like the most frequently used words? What if you did this analysis, but with snapshots of the website over time (rather than just the current moment)? So I got to building. Quadratic today doesn’t yet have the ability for your spreadsheet to run in the background on a schedule and append data. So I had to look elsewhere for a little extra functionality. My mind went to val.town which lets you write little scripts that can 1) run on a schedule (cron), 2) store information (blobs), and 3) retrieve stored information via their API. After a quick read of their docs, I figured out how to write a little script that’ll run once a day, scrape the site, and save the resulting HTML page in their key/value storage. From there, I was back to Quadratic writing code to talk to val.town’s API and retrieve my HTML, parse it, and turn it into good, structured data. There were some things I had to do, like: Fine-tune how I select all the editorial links on the page from the source HTML (I didn’t want, for example, to include external links to the White House’s social pages which appear on every page). This required a little finessing, but I eventually got a collection of links that corresponded to what I was seeing on the page. Parse the links and pull out the top-level domains so I could group links by domain occurrence. Create charts and graphs to visualize the structured data I had created. Selfish plug: Quadratic made this all super easy, as I could program in JavaScript and use third-party tools like tldts to do the analysis, all while visualizing my output on a 2d grid in real-time which made for a super fast feedback loop! Once I got all that done, I just had to sit back and wait for the HTML snapshots to begin accumulating! It’s been about a month and a half since I started this and I have about fifty days worth of data. The results? Here’s the top 10 domains that the White House Wire links to (by occurrence), from May 8 to June 24, 2025: youtube.com (133) foxnews.com (72) thepostmillennial.com (67) foxbusiness.com (66) breitbart.com (64) x.com (63) reuters.com (51) truthsocial.com (48) nypost.com (47) dailywire.com (36) From the links, here’s a word cloud of the most commonly recurring words in the link headlines: “trump” (343) “president” (145) “us” (134) “big” (131) “bill” (127) “beautiful” (113) “trumps” (92) “one” (72) “million” (57) “house” (56) The data and these graphs are all in my spreadsheet, so I can open it up whenever I want to see the latest data and re-run my script to pull the latest from val.town. In response to the new data that comes in, the spreadsheet automatically parses it, turn it into links, and updates the graphs. Cool! If you want to check out the spreadsheet — sorry! My API key for val.town is in it (“secrets management” is on the roadmap). But I created a duplicate where I inlined the data from the API (rather than the code which dynamically pulls it) which you can check out here at your convenience. Email · Mastodon · Bluesky