今年初めてスーパーアリーナのVIVA LA ROCKの3-4日め行ってきた。目当てのバンドも楽しかったバンドもいっぱいあったが、最終的にもっとも印象に残ったのは花冷え。だった。
The mythical modular monolith
So often I see people giving talks about how the microservice architecture is a failure. You end up losing transactional protections, you’ll have to “join” data across a network boundary, and that network boundary is “always” flaky. Wouldn’t it be much better if everything was in one process, where you could enjoy the benefits of transactions, neighboring data is just a method call away and the only network you have to worry about is the database connection?
Podman containers can’t talk to each other
The other day I decided to update my server-side rendering example, and I ran into a strange problem. While my compose.yaml hasn’t changed, my containers could not talk to each other. This was most apparent with the nginx container, which immediately crashed out with [emerg] 1#1: host not found in upstream. What gives?
After a quick debugging including on a different computer, it became clear that my compose.yaml should be fine: it worked without issues on the computer that used Docker, but didn’t work with Podman. The issue with Podman was soon clear too: looking at podman network inspect the "dns_enabled": false was an obvious culprit. That’s where things got interesting.
2024を振り返ろう
2024はあまりいい味が残る年にはならなかった。始まりはいいものの、そのあとは負の連鎖が続くという感じでなかなか評価が厳しい。
Tricking the JVM JIT into speed
On the Clojurians Slack, PEZ brought some delicious Fibonacci performance tuning from the “languages” repo. While I don’t think that benchmark is as useful as mesmerizing the moving circles are in the animated graphs, I had a few very confusing and interesting discoveries.
Step 1: watch Alex Miller’s talk about Clojure’s interop performance. Step 2: learn how to actually do all that stuff. Step 3: notice that recursion does things. Step 4: magic.
Untyped JS objects in ClojureScript
Working on a Chrome plugin I got to use ClojureScript in yet another new environment. After the usual browser setup, Node, Deno and Github Actions, this time it was the Chrome plugin system. While it was mostly a very smooth ride, I had a little trouble figuring out how to deal with a “Cannot infer target type in expression” warning.
It showed up while dealing with a HAR entry object passed in to my callback from devtools.network.onRequestFinished. The HAR object, while its shape is well defined, is not typed in a strict sense (though I guess there may be some type definition for it somewhere out there if I looked hard enough). That’s why when I tried to access its fields like (-> entry .-request .-url) the ClojureScript compiler (through Shadow CLJS) would complain about inferring the “target type” as above.
ClojureDartで自前でwidget作ろうとするときの注意点
やりたかったことは多言語対応の一環だった。flutter_localizationsの生成コードでBuildContextからAppLocalizationは取得できるが、それと別にOSの言語設定を監視したかった。そのために他のウィジェットを包むだけのものを用意して、ミドルウェア的な挙動でOSの言語設定をアプリのDBに保管したかった。でもなぜかそれを適応すると、今度はgo_routerのStatefulShellRouteを使った遷移が機能しなくなってしまった。
HTTP Signatures are RFC
If you’ve worked with Mastodon (or possibly other ActivityPub implementations too) HTTP Signatures might sound familiar. When notifying another server of an event, the request can be signed thus proving its authenticity, meaning that the receiving server doesn’t need to go and fetch the authoritative version from the origin. This reduces load on both the receiver of the event (less requests to send) and the origin (less requests to serve).
extend-protocolでClass/forName怒られるワケ
Clojureでプロトコルをよく使う。defprotocolで作ってextend-protocolで各種の型に実装すると、いろんな入力値にスムーズに対応できる。例えば暗号化周りで、ハッシュや署名の算出のためにバイト配列が必要な際、プロトコルを活かしていい感じのAPIが提供できる。
(defprotocol Byteish
(->bytes ^bytes [input]))
(extend-protocol Byteish
String
(->bytes [input] (.getBytes input)))